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CO2 geological storage combined with deep saline water recovery technology (CO2-EWR) is one of the most effective ways to reduce carbon emissions. Due to the complex structural features, it is difficult to use CO2-EWR technology in Huaiyin Sag, Subei basin, East China. In this study, the multi-source information superposition evaluation technology of GIS was utilized for the selection of CO2 storage sites and water displacement potential target areas in this area, which mainly focused on the sandstone reservoirs of Cretaceous Pukou Formation. Based on the results, a three-dimensional injection–extraction model was established. Various scenarios with different production/injection well ratios (PIR) were simulated. Research has shown that the suitability of the surrounding site of Huaiyin Power Plant can be divided into two levels: relatively suitable and generally suitable; the area in the generally suitable level accounts for more than 80%. At a PIR of 1, CO2 is distributed asymmetrically, whereas at PIRs of 2 or 4, CO2 is distributed symmetrically. When the number of production wells is constant, a higher injection rate results in a faster expansion rate of the CO2 plume. This means that the time taken for the CO2 plume to reach the production wells is shorter. Reservoir pressure increases rapidly after more than 60 years of CO2 injection at lower PIR values, while at higher PIRs, reservoir pressure eventually stabilizes. Higher PIR values correspond to higher gas saturation, indicating a greater capacity for CO2 sequestration with more producing wells. When PIR = 4, the total CO2 injection increased by 55.73% compared to PIR = 1. However, the extraction of saline decreases with an increase in the number of producing wells, resulting in a decrease in replacement efficiency. This study provides a theoretical basis and technical support for the implementation of large-scale CO2-EWR engineering and technology demonstration in this region. [ABSTRACT FROM AUTHOR]

The Xiaomojiu landslide is a typical high-elevation, long-runout landslide located in the Jinsha River Corridor. In this study, sequential InSAR time-series estimation was used to calculate the line of sight (LOS) surface displacements with descending and ascending Sentinel-1 images, and it turned out that the cumulative LOS surface displacement of the landslide was up to −78.4 mm during the period from October 2017 to April 2021 with the maximum LOS surface displacement rate of −38.5 mm/year. The landslide body could be divided into five zones (A, B1, B2, B3, and C) according to its topographical characteristics together with the LOS surface displacement time series. Combining engineering geological characteristics, LOS cumulative surface displacements with site investigation suggest that the Xiaomojiu landslide is likely to be a precipitation-triggered ancient traction rock landslide at the accelerated deformation stage. A dynamic simulation of the Xiaomojiu landslide with the PFC3D software shows that it could take approximately 65 s for the Xiaomojiu landslide from start-up to acceleration to deceleration to build-up of a barrier lake, followed by a simulation from the barrier lake to outburst floods with the HEC-RAS software indicating that the maximum depth of the outburst floods could be 13.5 m (15%), 24.6 m (25%), 42.1 m (50%), and 50.3 m (75%) along Qinghai-Tibet Plateau Transportation Corridor (QTPTC). It is believed that the results of this study provide a reference for landslide prevention along the QTPTC and the Jinsha River. [ABSTRACT FROM AUTHOR]

Water scarcity, the intensification of agricultural nonpoint pollution, and continuous deterioration of the ecosystem are serious problems in arid areas. Optimal allocation of water resources is the key way to achieve sustainable and efficient development of irrigated agriculture. An integrated multiobjective optimization model considering water-balance processes was developed under shallow groundwater environments to enhance comprehensive objectives and obtain optimal irrigation solutions. A simulation module of the physical processes of water movement among crop root zones, soil water, and groundwater aquifers, and a multiobjective optimization module of irrigation water allocation were incorporated into a general framework. It has the following advantages in terms of (1) illustrating variations of agricultural hydrological parameters (e.g., soil water content, groundwater depth, groundwater-based evaporation, and so on) in water movement processes; (2) obtaining a set of noninferior decision-making solutions through a modified nondominated sorting genetic algorithm (NSGA-II), which can maximize the interests for multiple parties; and (3) generating optimal solutions of irrigation water allocation and alleviating water scarcity, improving irrigation water productivity, and reducing negative environmental effects. To demonstrate its applicability, it was applied to optimize irrigation water allocation in the Jiefangzha Irrigation Subarea (JIS), China. It was firstly split into 44 irrigation subsystems, and each subsystem was assumed to be a homogeneous unit in meteorology, soil texture, and groundwater. Under the water competition between subsystems and rigid constraints of water availability, optimized results enhanced net economic benefits by 14.7%, saved 7.74% of irrigation water amount, and improved irrigation water productivity by 13% compared with status quo. Meanwhile, it can reduce graywater footprint of grain production by 58% compared with the average level of Hetao Irrigation District, China. [ABSTRACT FROM AUTHOR]

China's first Mars probe, the Tianwen-1, successfully landed on the Martian Utopia Plain on May 15, 2021. The multi-functional obstacle avoidance sensor (MOAS) has been the key navigation equipment for the entry, descent, and landing (EDL) operation of Tianwen-1. The MOAS integrates a landing camera and a laser imaging module and can acquire sequential optical images of the landing process of Tianwen-1 and high-resolution topography of the Martian surface. As a navigation sensor, the MOAS plays a key role in the processes of back cover avoidance, coarse obstacle avoidance, and hovering fine obstacle avoidance from the height of 10 km to landing. The MOAS's laser imaging module uses a new-generation scanning component, a two-dimensional MEMS scanning mirror, which is a unique feature compared to other space lidars. In this paper, optical and electronic designs of the MOAS are analyzed in detail. Based on the open-loop control feature of a MEMS scanning mirror, an online training and calibration method is proposed to increase the accuracy of optical angle control to 0.02°. In addition, the ground performance validation and the space environment testing of MOAS are described in detail. The inflight performance of MOAS is evaluated based on the sequential camera images and 3D point cloud data. In addition, the MOAS combines the attributes of a scientific instrument. The images obtained by the sensor can reconstruct the descending trajectory of Tianwen-1, determine accurate landing coordinates, and acquire information on the topography, surface reflectivity, and sand and dust of Mars. [ABSTRACT FROM AUTHOR]

Due to the complex feedback cycle relationship among water resources, energy, and food, the agricultural water management mode and concept with a single object or two objects as the core can no longer meet the inherent requirements of the coordinated, sustained, and healthy development of economy and society. A two-stage multiobjective decision-making method based on a θ -dominance evolutionary algorithm (θ -DEA) is proposed for the optimization of agricultural systems with a water-energy-food nexus. First, the Pareto noninferior solution set of the model is obtained by the evolutionary algorithm based on θ -DEA. Then, the economic benefit and carbon emission of each solution are evaluated, and the optimal solution is selected by using the multiobjective decision-making method based on interval-valued hesitant fuzzy sets and the technique for order preference by similarity to ideal solution (TOPSIS). Through a case study of the Hetao Irrigation District (HID), the best optimization results are obtained when the carbon footprint is 4.16×109 kg CO2 eq, and the economic benefit is 8.09×109 yuan. The example shows that the model can well select the optimal allocation solution of water resources, which not only has high economic benefits and low pollution discharge but also meets the subjective wishes of decision-makers. The model has good practicability and stability. [ABSTRACT FROM AUTHOR]

The Jinsha River flows through one of the most geologically complex regions in western China with extremely high altitudes and capricious climates. Frequent landslides (e.g., the Baige landslides on 11 October and 3 November 2018) occurred along its stretch which posed severe damage to bridges, dams, and roads, and put the safety of local residents at risk. Systematic and comprehensive landslide detection has been rarely carried out in the Jinsha River corridor because it is a wide and hard-to-reach region. With 30 years of development, InSAR has become an effective way to map ground motion, which in turn makes it feasible to detect active landslides over wide regions. However, several challenges remain in applying InSAR in the Jinsha River corridor, such as low coherence due to dense vegetation and/or large gradient surface movements, and atmospheric effects due to the spatio-temporal variations of the atmosphere (especially the part due to tropospheric water vapor). In this paper, we propose a framework to overcome the limitations of conventional InSAR through the integration of GACOS-assisted InSAR, advanced SBAS InSAR, and SAR pixel offset tracking techniques. This integrated framework enables us to detect active landslides under complex topographic and climate conditions. Our results show that the detected active landslides are largely controlled by active faults, most of them are found at elevations of 2500–4000 m, their slopes fall between 25 and 45 ∘ facing southwest and northwest, and 83.3% of the active landslides have a NDVI value of less than 0.3. Furthermore, precipitation is one critical triggering factor of active landslides, evidenced by the high temporal correlation between average precipitation and surface displacement time series. [ABSTRACT FROM AUTHOR]

This study implemented a stable Regional Reference Frame in Shanghai, East China (called SHRRF), using seven years of continuous GNSS observations from the Shanghai Continuously Operating Reference System stations (SHCORS) to examine reclaimed coast–land subsidence. A well−distributed core station network suitable for regional applications was derived. The instantaneous station coordinates and seven frame parameters (translations, rotations, and scale) were estimated at each epoch through minimum constraint during the process of aligning SHRRF to the International Terrestrial Reference Frame (ITRF14). The average root mean square error (RMSE) of all stations under SHRRF was within 1.5 mm horizontally and 5 mm vertically for most epochs. Simultaneously, compared with the ITRF14 solutions, the average RMSE for each site at all epochs was reduced by ~30% horizontally and ~10% vertically. A temporal consolidation settlement model of the reclaimed soil under self−weight was established by combining a geotechnical−derived model with high precision permanent GNSS vertical solutions under SHRRF. The model indicates that ~50% of settlements occurred within 3.6 years, with the whole subsidence time being 46 years. SHRRF provides a precise regional reference frame for use in many East China geophysical applications besides reclaimed coast–land settlement including hydrologic loading, microplate motions, and critical structure deformation monitoring. [ABSTRACT FROM AUTHOR]

A comprehensive field campaign, with measurements of HONO and related parameters, was conducted in summer 2018 at the foot (150 m a.s.l.) and the summit (1534 m a.s.l.) of Mt. Tai (Shandong province, China). At the summit station, high HONO mixing ratios were observed (mean ± 1 σ : 133 ± 106 pptv, maximum: 880 pptv), with a diurnal noontime peak (mean ± 1 σ : 133 ± 72 pptv at 12:30 local time). Constraints on the kinetics of aerosol-derived HONO sources (NO 2 uptake on the aerosol surface and particulate nitrate photolysis) were performed and discussed, which enables a better understanding of the interaction of HONO and aerosols, especially in the polluted North China Plain. Various evidence of air mass transport from the ground to the summit level was provided. Furthermore, daytime HONO formation from different paths and its role in radical production were quantified and discussed. We found that the homogeneous reaction NO + OH could only explain 8.0 % of the daytime HONO formation, resulting in strong unknown sources (Pun). Campaigned-averaged Pun was about 290 ± 280 pptv h -1 , with a maximum of about 1800 pptv h -1. Aerosol-derived HONO formation mechanisms were not the major sources of Pun at the summit station. Their contributions to daytime HONO formation varied from negligible to moderate (similar to NO + OH), depending on the chemical kinetic parameters used. Coupled with sensitivity tests on the kinetic parameters used, the NO 2 uptake on the aerosol surface and particulate nitrate photolysis contributed 1.5 %–19 % and 0.6 %–9.6 % of the observed Pun , respectively. Based on synchronous measurements at the foot and the summit station, an amount of field evidence was proposed to support the finding that the remaining majority (70 %–98 %) of Pun was dominated by the rapid vertical transport from the ground to the summit level and heterogeneous formation on the mountain surfaces during transport. HONO photolysis at the summit level initialized daytime photochemistry and still represented an essential OH source in the daytime, with a contribution of about one-quarter of O 3. We provided evidence that ground-derived HONO played a significant role in the oxidizing capacity of the upper boundary layer through the enhanced vertical air mass exchange driven by mountain winds. The follow-up impacts should be considered in regional chemistry transport models. [ABSTRACT FROM AUTHOR]

In the summer of 2018, a comprehensive field campaign, with measurements on HONO and related parameters, was conducted at the foot (150 m a.s.l.) and the summit of Mt. Tai (1534 m a.s.l.) in the central North China Plain (NCP). With the implementation of a 0-D box model, the HONO budget with six additional sources and its role in radical chemistry at the foot station were explored. We found that the model default source, NO + OH, could only reproduce 13 % of the observed HONO, leading to a strong unknown source strength of up to 3 ppbv h -1. Among the additional sources, the NO 2 uptake on the ground surface dominated (∼ 70 %) nighttime HONO formation, and its photo-enhanced reaction dominated (∼ 80 %) daytime HONO formation. Their contributions were sensitive to the mixing layer height (MLH) used for the parameterizations, highlighting the importance of a reasonable MLH for exploring ground-level HONO formation in 0-D models and the necessity of gradient measurements. A Δ HONO /Δ NO x ratio of 0.7 % for direct emissions from vehicle exhaust was inferred, and a new method to quantify its contribution to the observations was proposed and discussed. Aerosol-derived sources, including the NO 2 uptake on the aerosol surface and the particulate nitrate photolysis, did not lead to significant HONO formation, with their contributions lower than NO + OH. HONO photolysis in the early morning initialized the daytime photochemistry at the foot station. It was also a substantial radical source throughout the daytime, with contributions higher than O 3 photolysis to OH initiation. Moreover, we found that OH dominated the atmospheric oxidizing capacity in the daytime, while modeled NO 3 appeared to be significant at night. Peaks of modeled NO 3 time series and average diurnal variation reached 22 and 9 pptv, respectively. NO 3 -induced reactions contribute 18 % of nitrate formation potential (P (HNO 3)) and 11 % of the isoprene (C 5 H 8) oxidation throughout the whole day. At night, NO 3 chemistry led to 51 % and 44 % of P (HNO 3) or the C 5 H 8 oxidation, respectively, implying that NO 3 chemistry could significantly affect nighttime secondary organic and inorganic aerosol formation in this high-O 3 region. Considering the severe O 3 pollution in the NCP and the very limited NO 3 measurements, we suggest that besides direct measurements of HO x and primary HO x precursors (O 3 , HONO, alkenes, etc.), NO 3 measurements should be conducted to understand the atmospheric oxidizing capacity and air pollution formation in this and similar regions. [ABSTRACT FROM AUTHOR]

Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging at 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine and chlorine atoms. The halogen atoms increased the abundance of 'conventional' tropospheric oxidants (OH, HO2 and RO2) by 26%–73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent. [ABSTRACT FROM AUTHOR]

It is unclear whether the South China blocks have an affinity with continental Gondwana due to a lack of direct Pan‐African magmatic and metamorphic features. In this study, we conducted U‐Pb geochronological and Lu‐Hf isotopic analyses for detrital zircons from a sandstone of the Chang'an Formation of the Nanhua Group in the Longsheng region of northern Guangxi, with the aim of constraining the timing of sedimentation and information as to its source, as well as seeking evidence for Pan‐African events in the South China blocks. The results show that the ages of detrital zircons peaked at 654.7 ± 6.2 Ma, 773.2 ± 4.1 Ma and 821.9 ± 6.5 Ma, with some at 920–870 Ma; the youngest age indicates the existence of the Pan‐African thermal event. The ∊Hf(t) and TDM2 values demonstrate that the study area has experienced three stages of crustal growth at 3.0–2.4 Ga, 2.1–1.5 Ga and 1.3–0.9 Ga. With intensively distributed Neoproterozoic mafic‐ultramafic and granitic plutons emplaced at 830–810 Ma along the southwestern section of the Jiangnan Orogenic Belt and positive ∊Hf(t) values from a large group of zircon grains, it is proposed that the sediments of the Chang'an Formation (of Nanhua Group) were largely sourced from the southeastern margin of the Yangtze block. Comparison with the zircon age spectra of the Cathaysian block shows that about 79% of the Pan‐African aged detrital zircon grains that have TDM2 = 1352–1031 Ma and ∊Hf(t) = 3.68–8.79, were sourced from the recycled Grenvillian crust of the Cathaysian block, suggesting that the Cathaysian block had a close connection with Gondwana. [ABSTRACT FROM AUTHOR]

The influence of aerosols, both natural and anthropogenic, remains a major area of uncertainty when predicting the properties and the behaviours of clouds and their influence on climate. In an attempt to better understand the microphysical properties of cloud droplets, the simultaneous variations in aerosol microphysics and their potential interactions during cloud life cycles in the North China Plain, an intensive observation took place from 17 June to 30 July 2018 at the summit of Mt. Tai. Cloud microphysical parameters were monitored simultaneously with number concentrations of cloud condensation nuclei (NCCN) at different supersaturations, PM 2.5 mass concentrations, particle size distributions and meteorological parameters. Number concentrations of cloud droplets (NC), liquid water content (LWC) and effective radius of cloud droplets (reff) show large variations among 40 cloud events observed during the campaign. The low values of reff and LWC observed at Mt. Tai are comparable with urban fog. Clouds on clean days are more susceptible to the change in concentrations of particle number (NP), while clouds formed on polluted days might be more sensitive to meteorological parameters, such as updraft velocity and cloud base height. Through studying the size distributions of aerosol particles and cloud droplets, we find that particles larger than 150 nm play important roles in forming cloud droplets with the size of 5–10 µ m. In general, LWC consistently varies with reff. As NC increases, reff changes from a trimodal distribution to a unimodal distribution and shifts to smaller size mode. By assuming a constant cloud thickness and ignoring any lifetime effects, increase in NC and decrease in reff would increase cloud albedo, which may induce a cooling effect on the local climate system. Our results contribute valuable information to enhance the understanding of cloud and aerosol properties, along with their potential interactions on the North China plain. [ABSTRACT FROM AUTHOR]

A vast area in China is currently going through severe haze episodes with drastically elevated concentrations of PM 2.5 in winter. Nitrate and sulfate are the main constituents of PM 2.5 , but their formations via NO2 and SO2 oxidation are still not comprehensively understood, especially under different pollution or atmospheric relative humidity (RH) conditions. To elucidate formation pathways of nitrate and sulfate in different polluted cases, hourly samples of PM 2.5 were collected continuously in Beijing during the wintertime of 2016. Three serious pollution cases were identified reasonably during the sampling period, and the secondary formations of nitrate and sulfate were found to make a dominant contribution to atmospheric PM 2.5 under the relatively high RH condition. The significant correlation between NOR, NOR = NO3-/(NO3-+NO2) , and [NO2]2 × [O3] during the nighttime under the RH≥60 % condition indicated that the heterogeneous hydrolysis of N2O5 involving aerosol liquid water was responsible for the nocturnal formation of nitrate at the extremely high RH levels. The more often coincident trend of NOR and [HONO] × [DR] (direct radiation) × [ NO2 ] compared to its occurrence with [Dust] × [ NO2 ] during the daytime under the 30 % < RH < 60 % condition provided convincing evidence that the gas-phase reaction of NO2 with OH played a pivotal role in the diurnal formation of nitrate at moderate RH levels. The extremely high mean values of SOR, SOR = SO42-/(SO42-+SO2) , during the whole day under the RH≥60 % condition could be ascribed to the evident contribution of SO2 aqueous-phase oxidation to the formation of sulfate during the severe pollution episodes. Based on the parameters measured in this study and the known sulfate production rate calculation method, the oxidation pathway of H2O2 rather than NO2 was found to contribute greatly to the aqueous-phase formation of sulfate. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are considered to be persistent organic pollutants, which pose a great threat to human health and the surrounding environment. In order to explore the influence of informal electronic waste (e-waste) dismantling activities on inhabitants who live nearby, soil samples were collected from informal e-waste dismantling areas in Xinqiao, China and analysed for 16 United States Environmental Protection Agency (USEPA) priority PAHs. Results indicated that the 16 USEPA priority PAHs were found at all seven sampling locations. Sampling location 3, which was only 10 m away from a residential area, had 1053.69 μg kg−1 of PAHs and seriously exceeded the standard value specified by the Netherlands. The total percents of 4-ring and 5-ring PAHs accounted for 61.74 and 71.70%, respectively, indicating that most of the detected PAHs belonged to high-ring PAHs. The informal e-waste dismantling activities are the major sources of soil PAHs in Xinqiao. Furthermore, the concentration of seven carcinogenic PAHs was 114.76 μg kg−1 and represented a potential health risk to humans. Thereinto, benzo[a]pyrene contributed the most, accounting for more than 50% in these locations. Our results may provide a reference about the influence of informal e-waste dismantling activities on the surrounding inhabitants and suggest that e-waste dismantling activities must be conducted in a formal enterprise which is far away from residential areas. [ABSTRACT FROM AUTHOR]

The vague and fuzzy parametric information is a challenging issue in irrigation water management problems. In response to this problem, a generalized fuzzy credibility-constrained linear fractional programming (GFCCFP) model is developed for optimal irrigation water allocation under uncertainty. The model can be derived from integrating generalized fuzzy credibility-constrained programming (GFCCP) into a linear fractional programming (LFP) optimization framework. Therefore, it can solve ratio optimization problems associated with fuzzy parameters, and examine the variation of results under different credibility levels and weight coefficients of possibility and necessary. It has advantages in: (1) balancing the economic and resources objectives directly; (2) analyzing system efficiency; (3) generating more flexible decision solutions by giving different credibility levels and weight coefficients of possibility and (4) supporting in-depth analysis of the interrelationships among system efficiency, credibility level and weight coefficient. The model is applied to a case study of irrigation water allocation in the middle reaches of Heihe River Basin, northwest China. Therefore, optimal irrigation water allocation solutions from the GFCCFP model can be obtained. Moreover, factorial analysis on the two parameters (i.e. λ and γ ) indicates that the weight coefficient is a main factor compared with credibility level for system efficiency. These results can be effective for support reasonable irrigation water resources management and agricultural production. [ABSTRACT FROM AUTHOR]

To readily addressed three key issues including fuzzy parametric information, multiple objectives and fractional ratios in planning problems, this study presents a fuzzy credibility-based multi-objective linear fractional programming approach for building the linkage between agricultural water-food-environment nexus and crop area planning. This approach is developed by incorporating fuzzy credibility-constrained programming into multi-objective linear fractional programming within the optimization model. To demonstrate its applicability, the approach is then applied to the Hetao Irrigation District in the northwest China to unite the multiple objective problems in agricultural irrigation with crop area planning. Three ratio optimization problems associated with agricultural, economic and environmental objectives are concurrently considered including maximum economic benefit per unit of irrigation water, maximum crop yield per unit of irrigated area and minimal grey water footprint per unit of crop production. Therefore, this study has the following advantages. (1) Fuzzy parameters existing in the objective and violated constraints can be effectively tackled. (2) The multiple ratio optimization problems can be efficiently solved through a linearization procedure in a straightforward manner, thereby reflecting desired system efficiency and reducing computational difficulties. (3) The mathematical and practical interactions of agricultural water-food-environment nexus can be investigated based on intermediate variables, i.e., irrigated area, irrigation water, crop yield, economic benefits and greywater footprint. (4) Optimal solutions can be flexibly generated to facilitate crop area planning through given aspiration levels of objective goals and credibility levels of constraints. The results indicate that optimal objective values have slight changes with the form of each objective (e.g., maximization or minimization). The results are useful for facilitating insightful interpretation of inter-relationships among sustainable agricultural production, efficient irrigation water use, and favorable agro-ecological conditions. [Display omitted] • A fuzzy credibility-based multi-objective linear fractional programming approach is developed. • Linkage between agricultural water-food-environment nexus and crop area planning is analyzed. • A linearization procedure is introduced to solve the multiple ratio optimization problems. • The results support understanding of interactions among agriculture, water and environment subsystems. [ABSTRACT FROM AUTHOR]

Arsenic (As) contamination has become the environment issue of global concern. In China, large area of farmland and the site soil were contaminated by As, which means that suitable remedying methods were urgently needed. Phytoremediation, as one of environment-friendly soil remediation techniques developed in recent years, shows a bright future for the remediation of As contaminated soils. However, phytoremediation efficiency needs to be enhanced further because of low concentration of bio-available As in the soils. A triangle flask culture experiment was carried out to study the effects of functional species, isolated from As-polluted soils, that could improve As mobility from the soil. These species included two bacilli, B1 and B2 ( Brevibacillus) and two fungi, F1 ( Trichoderma), F2 ( Fusarium). They could transform the concentration of As fractionation in the soil sterilized by the method of Co-γ ray. Through the experiment, the concentrations of non-specifically-sorbed and specifically-sorbed As fractionation, and pH value of culture solution with inoculated treatment were higher than that with the control. Especially, the concentration of non-specifically-sorbed As fractionation in the treatment-inoculated species was 2 to 6 times higher than that of non-inoculation treatment. Moreover, two bacilli and two fungi could produce IAA, which was conducive to the plant survival when they were jointly used in remedying the As-contaminated soil. [ABSTRACT FROM AUTHOR]

[Display omitted] • An integrated simulation-optimization framework is proposed for irrigation planning. • It makes dynamic decision of irrigation planning possible. • It achieves the maximum credibility level of the fuzzy objective function. • It controls salt accumulation at the end of crop growth period through constraints. An integrated simulation-optimization framework is developed under uncertainty to enhance irrigation water productivity and control salinity in an arid area. A full fuzzy dependent linear fractional programming approach is formulated by incorporating fuzzy dependent-chance programming, fuzzy credibility-constrained programming and linear fractional programming within a general framework of irrigation planning. Then, simulation module concerning water, salt balance process and crop water-salt production functions enables to quantify daily physical process of water and salt movement among the soil water, crop root zone and groundwater aquifers. Thus, this study can readily handle fuzzy uncertainty existing concurrently in the ratio objective (i.e., economic water productivity) through the concept of fuzzy dependent chance and double-sided constraints. It can also simultaneously provide the maximum credibility level that the objective is achievable and credibility levels implying that optimal solutions are believable. Besides, daily variations of simulated physical parameters are illustrated corresponding to management strategies. To demonstrate its applicability, it's then applied to a case study of irrigation planning in the Jiefangzha Irrigation Subarea in Hetao Irrigation District, northwest China. Results can clearly analyze tradeoffs among satisfaction degree of fuzzy objective, fuzzy constraints and optimal solutions. Moreover, by examining different management targets and salt accumulation constraints, this study demonstrates the merits and importance of the work to promote irrigation water productivity and control salinity. Dynamic decision making of irrigation planning is possibly made by coupling daily simulation and optimization modules. Therefore, these findings can support decision makers to identify appropriate solutions for irrigation planning. [ABSTRACT FROM AUTHOR]

Abstract: The dustiness on the remote Tibetan Plateau and its trend within the ongoing global warming perspective are not well understood. In this study, we present the detailed dust history from 1850 to 2004 AD on an annual timescale from a shallow ice core from Tanggula, central Tibetan Plateau. Two periods of strong dustiness, one at the end of the Little Ice Age (1860–1874) and the other during the period 1930–1954, occurred during low oxygen isotope stage, which is correlated with temperature on multi-year and decadal timescales. The extremely high level of dust flux between 1860 and 1874 was unique – this level has not occurred again during the past century, and the 1930s'' dustiness was characterized more by strong wind and dust storms rather than drought, as shown by great grain size but low dust flux. We have used the composite analysis of modern meteorological data to study the possible dustiness mechanism and found that strengthened high-level westerlies over the Tibetan Plateau and intensified low pressure activities in the upward potential source regions, such as Tarim Basin, are the possible causes for high dust flux in Tanggula. Those results have revealed that although the dustiness on the Tibetan Plateau normally occurs in cold conditions, pronounced warming since the 1960s can change the dust pattern and strengthen the dustiness in this remote and high-altitude region, and can thus induce associated environmental issues by creating dustier conditions. [Copyright &y& Elsevier]

Luhuitou fringing reef, which has been seriously affected by human activities and terrestrial runoff, has degraded quickly in recent decades. However, direct impact by hyperthermal stress has probably been minimal because of the influence of the Qiongdong upwelling in summer. Seawater temperature anomalies in 2010 resulted in mean monthly seawater temperatures in summer to be 1–2°C higher than in the same period of the 3 preceding years. Moderate coral bleaching at Luhuitou fringing reef was observed in the summer of 2010 due to high thermal stress. Montipora was the most susceptible taxon, whereas Galaxea fascicularis and Pocillopora damicornis were among the least susceptible taxa. Mortality of Montipora was 21.7%, whereas for the remaining taxa it was less than 5%. No mortality was observed for tabular Acropora, G. fascicularis, P. damicornis, Favites and Leptoria. Most taxa showed relatively high bleaching in larger colonies compared with that in smaller ones. Juvenile coral colonies showed less bleaching (3%) than adult coral colonies (28%). Our study suggested that although most taxa in the survey area might recover from this moderate coral bleaching episode, coral reproduction in the year following bleaching may be adversely affected. [ABSTRACT FROM AUTHOR]

This research aimed to identify and characterize individual spherical fly ash particles extracted from surface snow at Urumqi Glacier No.1 (UG1), Eastern Tien Shan, central Asia. Characterization of the spherical particles (i.e. morphology, chemical composition and genesis) was obtained by scanning electron microscopy coupled with energy dispersive X-ray spectrometer (SEM-EDX). This method enabled the characterization of submicroscopic spherical particles, which were present in very small quantities. Spherical particles and agglomerates were identified according to their morphology in five snow samples. Prevalent particle types in all samples were granular spherical particles, hollow spherical particles, irregularly shaped carbonaceous particles and agglomerates. The vast majority of spherical particles in our samples had mostly smooth and glossy surfaces, although these particles varied in diameter and elemental composition. The diameter of fly ash particles ranged from 0.76 to 16.7 μm, with an average of 3.79 μm (median: 3.21 μm). Individual particle analyses of elemental composition showed that particles formed in combustion were mainly composed of carbon, silicon, aluminum and trace elements (e.g. Na, K, Ca, Fe). Some spherical fly ash particles contained toxic heavy metals (e.g. Pb, Cr, As, Zn), and indicated that fly ash particles acted as the main possible carriers of toxic heavy metals deposited in snow and ice of glaciers in high altitudes of central Asia. On the basis of chemical information obtained from EDX, the fly ash particles deposited in the snow could be classified into four types. Namely, Si-dominant particles, with average diameters of 3.24 μm were formed by industrial coal combustion via high temperature processes in typical coal-fired heating stations and thermal power plants. Moreover, Fe-dominant particles, with average diameters of 3.82 μm, and Ti-dominant spherical particles formed by lower temperature processes in foundry and iron or steel plants. In addition, C-dominant particles, with average diameters of 8.43 μm, formed from unburned coal. Fe-dominant particles had larger average diameters than Sidominant particles, indicating that the former were easier to form and developed earlier in the furnace because of their differential melting points of compositional oxide. Backward air mass trajectory analysis suggests that the developed urban regions of central Asia contributed the primary fly ash particles from industrial combustion to the study site through the high-level westerlies jet steam. [ABSTRACT FROM AUTHOR]

Abstract: This study presents the Sr and Nd isotopic composition of dust from a shallow Dunde ice core (38°06′N, 96°24′E, 5325m a.s.l.), Northern China, in order to trace its source regions and the provenance of long-range transported (LRT) Asian dust. Dunde dust samples show similar Sr (87Sr/86Sr averages 0.719982 and varies between 0.715220 and 0.721874) and Nd (εNd(0) averages −10.6 and ranges from −11.1 to −9.9) isotopic composition to desert sand from Taklimakan and Qaidam, revealing that the Tarim and Qaidam Basins are the most possible source areas for Dunde dust, while the contribution from Badain Jaran and Tengger seems very small or unlikely. Our results indicate that materials from Taklimakan can be entrained from the Tarim Basin and transported to Qilian Shan by Westerlies under the present climate. The Sr–Nd isotopic composition of Dunde dust, which is a good analogue for the long-range transported Asian dust, resembles that of North Pacific and Greenland dust, indicating that the important provenance of end members of the Asian dust seems to be Taklimakan on a regional scale. [ABSTRACT FROM AUTHOR]

Abstract: The Dunde ice cap (38°06''N, 96°24''E, with a summit of 5325 m) is situated at the centre of the northern Chinese deserts and receives dust from these regions. Here, we present the trace and rare earth element (REE) compositions of dust extracted from a shallow ice core from the Dunde ice cap, which provide a framework to trace the source of Dunde dust. Trace and REE parameters of Dunde dust show characteristics of a typical eolian deposit, with an average La/Th ratio of 2.6, a Th/U ratio of 3.7, and a strong negative Eu anomaly (0.61). The dirty layers in the ice core section have the same element characteristics as in the clear layers, indicating that the dust in Dunde is well-mixed and has a stable composition. Trace element and REE ratio plots show that Dunde dust has a similar composition to the finer fraction materials in the Taklimakan desert, suggesting that the Tarim Basin might be an important source for Dunde dust under the present circulation, but not favoring a material contribution from Badain Jaran. Our results reveal distinct differences in composition between Dunde dust and Chinese loess materials, which suggests that they have different sources. [Copyright &y& Elsevier]

The challenge of irrigation planning is that it involves various system components, which is further exacerbated by uncertainties and risk preference in making decisions. This study presents a simulation-optimization framework under uncertainty by incorporating fuzzy credibility-based optimization model with the Hurwicz criterion and daily water balance simulation for irrigation planning. The developed methodology can effectively handle fuzzy uncertainty in the objective function and constraints and readily analyze tradeoffs between optimal solutions of irrigation planning and risks associated with the decision-makers' preferences. It can also derive several physical parameters expressed as water depth from the water balance of root zone for determining optimal irrigation water amount. The Hurwicz criterion, fuzzy credibility constraints and other irrigation-related constraints are imposed on the study system through the developed framework. Then, its applicability is illustrated with a real case study in the Jiefangzha irrigation subarea in the Hetao Irrigation District, northwest China, which is an arid area. Optimal results using three risk-related parameters, i.e., nine preference weights (λ = 0.1, 0.2, ... and 0.9) of objective function, and three credibility levels (α = 0.7, 0.8 and 0.9, β = 0.7, 0.8 and 0.9) of fuzzy constraints, have been generated for supporting irrigation planning. Based on these outcomes, system benefits resulting from agricultural production have a slight growth with preference weights increase from 0.1 to 0.9, showing that optimistic criterion plays a decisive role in optimal irrigation planning solutions, especially when preference weights are greater than 0.7. Daily groundwater depth is presented in the given 81 scenarios for comparison, showing the usefulness of the developed framework in practical applications. Therefore, these findings are helpful for supporting irrigation planning and balancing tradeoffs between irrigation planning and risk preference for sustainable irrigated agriculture. • A simulation-optimization framework under uncertainty is proposed for irrigation planning. • Fuzzy uncertainty in the objective function and doubles-sided constraints, and risk preference are tackled. • Daily variations of simulated physical parameters are illustrated. • Flexible solutions of irrigation planning under different credibility levels and preference weights are generated. • Tradeoff between irrigation planning and risk preference of decision-makers is balanced. [ABSTRACT FROM AUTHOR]

An interval nonlinear double-sided fuzzy chance-constrained programming (INDFCCP) approach is formulated to effectively allocate irrigation water among competing water users. The INDFCCP approach is formulated by combining inexact quadratic programming (IQP) and double-sided fuzzy chance-constrained programming (DFCCP) within a general optimization framework. This approach has the following features. (1) It's able to handle interval and fuzzy uncertainties, and nonlinearity existing in the objective functions. (2) It's capable of addressing these fuzzy constraints and fuzzy variables where different confidence levels and satisfaction degree levels should be satisfied. (3) Each fuzzy chance-constraint can be further analyzed with the maximum and minimum reliability scenarios, which makes it possible to reflect variations of system conditions. (4) Interval quadratic crop water production functions (IQCWPFs) are employed in place of deterministic ones to quantitatively describe the mathematical relationships between crop yields and actual crop evapotranspiration (or irrigation water applied). Then, to demonstrate its applicability and feasibility, the INDFCCP approach is applied in the Yingke Irrigation District (YID), northwest China for allocating irrigation water to three crops in three subareas under uncertainty. Finally, more flexible decision solutions regarding optimal irrigation water allocation have been generated and analyzed under different predetermined confidence levels, showing several advantages of the INDFCCP approach with respect to the deterministic one. Under the same confidence level, system benefits under the minimum reliability scenario (e.g. [499.6, 909.7] × 106 Yuan, α = 0.5) are higher than that under the maximum reliability scenario (e.g. [498.7, 908.9] × 106 Yuan, α = 0.5). From above outcomes, the INDFCCP approach provides more appropriate results and reliable scientific bases needed for better managing irrigation water in irrigated agricultural areas. • An interval nonlinear double-sided fuzzy chance-constrained programming approach is developed. • Interval quadratic crop water production functions are estimated based on interval regression method. • The model is applied to a real case study in an arid area in northwest China for irrigation water resources allocation. • Cost-effective solutions can be generated by introducing confidence levels and the minimum and maximum reliability scenarios. [ABSTRACT FROM AUTHOR]

• An improved interval-based fuzzy credibility-constrained programming model is developed for irrigation water management. • It improves upon existing studies based on the deterministic CWPFs by using ICWPFs. • It explores weight coefficients of possibility and necessity to represent the various preferences of decision makers. • A higher weight coefficient and a lower credibility level under high water level will lead to a greater system benefits. In response to uncertainties and complexities in the irrigation water management systems, this study presents an improved interval-based fuzzy credibility-constrained programming (IIFCCP) model for optimizing the allocation of irrigation water resources under uncertainty. Mathematical techniques of interval parameter programming (IPP), improved fuzzy credibility-constrained programming (IFCCP) and interval crop water production functions (ICWPFs) are incorporated into a modeling framework for irrigation planning. Thus, this model has the following several advantages in irrigation water management. First, it can not only address interval and fuzzy uncertainties, but also analyze tradeoffs between irrigation water amount and agricultural production returns, to maximize the agricultural economic benefits. Second, it further improves upon existing studies on deterministic CWPFs by using the ICWPFs to reflect uncertain information in the practical applications. Third, it makes a novel attempt to explore weight coefficients (i.e. the proportion of possibility in estimating credibility) to represent various preferences of decision makers. Fourth, it provides more flexible strategies by considering various weight coefficients and credibility levels. Then, the proposed model is applied to a case study of irrigation water management in the middle reaches of the Heihe River Basin, northwest China. Therefore, optimal decision solutions for the allocation of irrigation water under different scenarios, i.e., the combinations of three water levels, four credibility levels and nine weight coefficients, will be obtained and analyzed. A greater system benefits will be achieved at a high weight coefficient and a low credibility level, especially weight coefficients are assigned as 0.8 and 0.9. Additionally, these solutions can provide detailed tradeoffs among system benefits, credibility levels and weight coefficients. Comparisons with the results from deterministic CWPFs and conventional FCCP method indicate that the IIFCCP method has an enhanced practical applicability in actual irrigation water management under uncertainty conditions in arid areas. [ABSTRACT FROM AUTHOR]

• A new irrigation-drainage collaborative optimization model is developed. • It explores the more applicable irrigation and drainage water allocation solutions. • The developed model will lead to greater benefits than conventional optimal model. Agricultural production in arid and semi-arid area faces a global problem of water resources shortage and land salinization. Irrigation and drainage are the important measure to enhance crop yield and control soil salinity. Generally, at field scale only irrigation is optimized to pursue the higher water use efficiency and crop yield, while drainage is difficult to optimize owing to controlled by dynamic groundwater levels. Here, we develop a new collaborative optimization model of irrigation and drainage to improve irrigation water use efficiency and to control soil salinity. The model is formulated by integrating simulation of physical processes of field water - salt balance and a genetic algorithm-based optimization model. The new model is to search optimized irrigation and drainage strategic decision for enhancing field economic benefit with the condition controlling salinity with limited water resources. Then, a case study on optimally allocating irrigation and drainage water to different growth stages of maize field in the Hetao Irrigation District, arid area of northwest China shows enhanced applicability of the developed model. Five groundwater depth levels (1 m, 1.5 m, 2 m, 2.5 m and 3 m) and five groundwater salinity levels (2 g/L, 2.25 g/L, 2.5 g/L, 2.75 g/L and 3 g/L) are provided to show and compare the solutions of the optimal irrigation and drainage water allocation. Results indicate the developed model can supply reasonable field monthly irrigation and drainage decision with considering field hydrology, especially contribution of groundwater to crop water demand and groundwater role to soil salt accumulation. The contrary relationship between system benefit and irrigation water use efficiency was described successfully by the developed model. And compared with traditional single irrigation optimization model, the developed irrigation-drainage collaborative optimization model can enhance drainage function to keep the optimal groundwater levels and improve the system benefit by 0–8%. Overall, the developed model can provide more applicable irrigation water and drainage strategies to the sustainable development of irrigation agriculture. [ABSTRACT FROM AUTHOR]

• A new irrigation management framework coupling water/salt process simulation and uncertain optimization was developed. • The framework emphasizes on agricultural sustainability with higher water use efficiency and soil salinity controlling. • Shallow groundwater level and soil salinity constraint have significant effects on the irrigation allocation decision. Field irrigation water management depends on interactions among crop yield, soil water/salt and groundwater/salt in arid irrigation area with shallow-saline groundwater. This paper presents a novel uncertainty simulation-optimization framework for irrigation water allocation and sustainable agricultural environment, which integrates simulation of physical processes of soil-groundwater water and salt balance into an uncertainty-based optimization model. The impacts of crop evapotranspiration, soil water and salt and groundwater levels are interactively involved in the simulation model. Uncertainties (economic and crop parameters, available water amount) presented as fuzzy boundary intervals and probability distribution functions are considered in the optimization model. This field irrigation water allocation framework emphasizes the role of field soil water and salt movement processes to decision-making of irrigation water allocation. Then, the proposed simulation-optimization framework was applied to a case study in the Hetao Irrigation District, an arid area of northwest China where soil salinity is a serious environmental problem induced by irrigation and shallow groundwater. Therefore, optimal irrigation water allocation solutions can be generated for providing decision makers with reliable decision options where the maximum system benefits resulting from sustainable agricultural production are desired. Furthermore, the results can support analysis of interrelationships among system benefits, water allocation planning and groundwater depth, soil salt content constraints. Scenario analysis (groundwater table depth (GTD) = 1, 1.5, 2, 2.5, 3 m and no groundwater exchange consideration) showed that the maximum net benefit could be [27469, 44818] Yuan with the groundwater table depth of 1.5 m. Also, the irrigation water allocation changed when the salt constraint was considered, which indicates that the results obtained by the developed framework can alleviate soil salinization to a certain degree. Therefore, this framework can provide more effective information for the irrigation water management and soil salinization control, which is meaningful for the sustainable development of irrigation agriculture. [ABSTRACT FROM AUTHOR]

In this study, an interval quadratic fuzzy dependent-chance programming (IQFDCP) model is proposed for irrigation water management under uncertainty. This model can deal with the interval and fuzzy uncertainties encountered in optimal irrigation water resources allocation problems. It takes optimal credibility level of system revenue as the objective function for addressing the conflict between maximum system revenue and the credibility level of the system revenue. By providing three scenarios of precipitation, the optimal solutions are obtained. The developed model is applied to a case study for irrigation water allocation in Minqin Oasis, Wuwei city, northwest China. This study can help determine how much irrigation water should be allocated to different crops under the maximum credibility level of the system revenue. The optimal solutions can provide a certain credibility level of system revenue corresponding to different scenarios and mitigate the system-failure risk level of water shortages in arid areas. Moreover, because the IQFDCP can objectively reflect the interrelationship among crop irrigation water amount, system revenue, and system-failure risk level, the results are able to provide advices to decision makers for efficiently managing water resources in different scenarios. [ABSTRACT FROM AUTHOR]

Two-stage programming (TSP) is popular in resources planning management, especially for limited and precious resources. Remarkable study has been done to improve the model performance. However, one of the biggest obstacle is lack of objectivity when it comes to penalty quantification derived from recourse behavior. Besides, much attention has been paid in the resources deficiency penalty but little in resources residual, which may lead to wasting. In order to clarify the physical meaning of mathematical equation for recourse penalty from both resources scarcity and surplus, the production frontier was estimated and the technical efficiency and shadow prices of resources were introduced into TSP to characterize the resources deficiency and residual penalty, respectively. Then, an intuitionist fuzzy interval two-stage stochastic programming (IFITSP) was generated integrating the uncertainty of fuzzy membership and traditional TSP. An integrated solving approach was proposed coupling several previous uncertain programming methods and an improved robust interval TSP method. A case study was conducted in an arid area of northwest China to schedule agricultural cultivation scale based on limited water resources. The inefficiencies were [0.26, 0.49], [0.14, 0.37] and [0, 0.03] for GZ, LZ, and GT. The shadow prices of GZ, LZ, and GT in 2015 were 12.94, 2.61, 2.67 Yuan/m3 respectively, indicating the sever water crisis of GZ. The relatively unbiased and abundant decision could be generated by the developed IFITSP to help decision makers with various preferences make tradeoff between benefits and basic crop production requirement as well as balance resources deficiency and surplus. The results also show that the developed model could unveil the uncertainty influence of model inputs on decision strategies and trigger managers to deeply analyze subjective effect and associated risk. By comparison, the proposed methodology can not only clarify the physical meaning of penalty but deal with more complex uncertainty than previous methods. Therefore, the established model can provide reliable and scientific support for resources planning with recourse. • Production frontier was estimated to help clarify the physical meaning of recourse penalty in two-stage programming (TSP). • An intuitionist fuzzy interval TSP was generated involving multiple uncertainties. • An integrated solving approach was proposed including an improved method for interval TSP. • A case study of planning cultivated area based on limited water resources was demonstrated. • The established methodology can be widely applied to resources planning management. [ABSTRACT FROM AUTHOR]

When planning agricultural production, planting area and water allocation are two major subjects faced by decision makers. In this study, a framework integrated Nerlove supply response model (Nerlove model) and interval fuzzy credibility-constraint bi-level programming (IFCBP) model is developed for planning the agricultural production in arid and semi-arid regions. Through Nerlove model, the planning process of crop planting area was described as an economic problem for forecasting farmers' behavior rather than an optimization problem for allocating farmland resources, and the relationship between crop planting area and market price can be obtained and further provide credible future crop planting area information. The IFCBP model can not only deal with uncertainties presented as interval and fuzzy numbers but also examine the credibility of the constraints and handle tradeoffs between two-level decision makers. To solve the IFCBP model, a solution method based on the interval interactive algorithm and credibility-cut method is proposed. Then, to verify the validity of the developed framework and solving method for agricultural production planning, they were applied to a real-case in the middle reaches of the Heihe River basin, northwest China. The forecasting results obtained from Nerlove model have better performance in predicting the future planting area of corn and vegetable than wheat, indicating that wheat plays a more vulnerable role in the decision-making process of planting area owing to its higher substitutability. The results show that the proposed framework can tackle two-level decision makers' concerns under uncertainties featured as inexact and fuzzy numbers, which can help regional managers plan future resources effectively. Furthermore, a comparison was made between IFCBP and two corresponding single-level models in this study. The comparison indicates that the developed model provides an effective tradeoff between two decision makers from different decision-making levels in IFCBP. The developed framework provides managers an effective way to plan agricultural production in arid and semi-arid regions, and the developed model and related thinking may help solve similar problems. • An agricultural production planning approach based on interval fuzzy credibility-constrained bi-level programming (IFCBP) and Nerlove supply response theory. • Both objective and subject factors are considered through the entropy method and analytic hierarchy process method separately. • This approach is applied to a case study for planning crop planting area and irrigation-water allocation. • The results can support water managers formulate more efficient agricultural production planning strategy. [ABSTRACT FROM AUTHOR]

• A novel optimization approach for agricultural water-food-energy nexus is developed. • Electricity, bioenergy and light energy are modeled, optimized and coordinated. • Dynamics and uncertainties in the nexus are simultaneously managed. • Conflicts between multiple energy sources and various resources are balanced. • Nexus sustainability and resource/energy use efficiency are improved. Synergistic regulation of various agricultural resources in agricultural water-energy-food nexus systems is important for understanding the key regulatory processes and related synergistic relationships. However, regulation with the goal of multienergy interaction and coordination to adapt to environmental changes is extremely challenging. As a solution to the problem, an uncertainty-based modeling approach is proposed for the optimal regulation of water, soil and energy resources from a multienergy synergy perspective by integrating multiobjective nonlinear programming, left–right type fuzzy numbers and credibility programming into a framework. The approach aims to assess the interactions and synergistic relationships among biomass electrical energy, light energy, and hydroelectric energy, clarify the dynamic characteristics of resource allocation and socioeconomic and environmental effects, and capture the high uncertainty in the nexus area. This study contributes to the efficient and sustainable management of agricultural water, energy and land resources. The approach was tested and implemented based on a case study of Jinxi Irrigation District in China. The results reveal that there are trade-offs and games among the light use efficiency, hydroelectric energy and biomass energy, and their coordination enhances the system synergy among resources, the economy and the environment by 12.22%, with a 2.67% increase in the irrigation water use efficiency and a 4.92% increase in the energy use efficiency. Uncertainties significantly affect the synergy among multiple energies. More water will promote collaborative energy management, with the coordination development degree will increase by 2.20% when the water quantity increases by 4.16%, however, it accompanied higher water scarcity risks. [ABSTRACT FROM AUTHOR]

Fine particle pH plays an important role in aerosol chemistry. Understanding of influencing factors and evolution process of fine particle pH is helpful to facilitate the improvement of air quality management strategies. Here, we performed simultaneously field measurement at Mt. Tai and the surrounding urban site during the summer of 2018, and analyzed comprehensively fine particle pH and its driving factors based on the sensitivity tests. The results indicated that ambient temperature (Temp), atmospheric relative humidity (RH), TNH 3 (= NH 4 + + NH 3) and SO 4 2− were the dominant factors for fine particle pH. The switch between RH-sensitive and Temp-sensitive regimes with variation of RH at the mountain site implied that fine particle pH was more sensitive to RH at Mt. Tai. Elevated TNH 3 could not sufficiently raise fine particle pH to neutral at relatively high SO 4 2− levels, whereas had a significant effect on fine particle pH when SO 4 2− concentration was relatively low. Considering the current levels of TNH 3 in summer of the North China Plain (NCP), fine particle pH was more sensitive to SO 4 2− at present. However, the sensitive factor of fine particle pH in the future is expected to shift from SO 4 2− to TNH 3 with declining SO 2 emissions and increasing NH 3 emissions, leading in turn to the evident increase of fine particle pH. Elevated fine particle pH and abundant TNH 3 may enhance secondary inorganic aerosol production, and thus effectively synergetic control of SO 2 and NH 3 is urgently needed to be considered in the NCP and even in other regions of China. [Display omitted] • The driving factors of fine particle pH at Mt. Tai were analyzed for the first time. • The relative increment [H+] method was firstly adopted to explore pH-WSIs sensitivity. • Fine particle pH in summer of the NCP was sensitive to RH, Temp, TNH 3 and SO 4 2-. • The pH sensitive factor in the future is expected to shift from SO 4 2- to TNH 3. • Synergistic control of SO 2 and NH 3 should be considered to balance fine particle pH. [ABSTRACT FROM AUTHOR]

• A full fuzzy-interval credibility-constrained nonlinear programming (FFICNP) model is proposed under uncertainty. • This approach is applied to a case study for planning irrigation water allocation in the Zhanghe Irrigation District. • A lower credibility level corresponds to higher net system benefit and system efficiency. • The results support in-depth analysis of interrelationships among water allocation schemes, system benefits, and credibility levels. To address the water shortage caused by various natural conditions and ineffective irrigation water management in the Zhanghe Irrigation District (ZID) of the Yangtze River basin in China, a full fuzzy-interval credibility-constrained nonlinear programming (FFICNP) model is developed under uncertainty. Derived through incorporating fuzzy credibility constrained programming into the Jensen model optimization framework, FFICNP can not only address intervals (single uncertainty) and fuzzy-interval sets (dual uncertainties) in the model objectives and double-sided constraints, but also reflect nonlinear responsive relationships between the crop yields and irrigation levels by introducing the crop water production functions (CWPFs) under different growth stages. Moreover, an expected-value-based (EVB) approach is introduced to solve the FFICNP model. The FFICNP model is then applied to the case study of irrigation water allocation in the ZID for demonstrating its applicability. Optimal solutions can be generated from the FFICNP model for solving the irrigation water allocation problem under uncertainty. The results indicate that a lower credibility level corresponds to a higher level of system benefits and system efficiency. The system benefits of ZID in a wet year are [17.72, 24.23] × 109 CNY when λ = 1.0 and [17.79, 25.03] × 109 CNY when λ = 0.6. These findings from the FFICNP model can support in-depth analysis of interrelationships among irrigation water allocation schemes, system benefits, and credibility levels, and thus contribute to the effectiveness of irrigation water management under various inflow levels and complex uncertainties. [ABSTRACT FROM AUTHOR]

Agricultural water scarcity is a global problem and effective management of limited water resources for irrigation to meet socioeconomic demands for sustainable development is a huge challenge. A stochastic multi-objective non-linear programming (SMONLP) model is developed for the identification of sound irrigation water allocation schemes. The SMONLP model improves upon previous methods by tackling contradictions of society-economy-resources as well as reflecting uncertainty expressed as probability distributions in an agricultural irrigation system. The SMONLP model permits in-depth analyses of various water allocation policies that are associated with different levels of water supply and climate change. The developed SMONLP model is applied to optimal irrigation allocation in a semi-arid river basin in China. Results reveal that the model coordinates the regulation of interactions of society-economy-resources by balancing the targets of water productivity, allocation equity, profit, economic benefit risk, blue water utilization, and leakage loss. Moreover, surface water availability associated with different violation risk probabilities can lead to the changes in comprehensive benefit of society-economy-resources and irrigation shortages. Nearly each of the 17 irrigation regions suffers from water deficit, because water is insufficient to satisfy the requirement of crops, however, the degree of water shortage is gradually weakened when flow level ranges from low to high. The coordination degree is also used to evaluate the sustainability of water allocation and the results of comparison show that the irrigation water allocation under RCP 4.5 presents lower coordination of society-economy-resources which are mainly attributed to the aggravated contradiction between water supply and demand. A real world study demonstrates the practicability of the developed model, allowing the river basin authorities to determine irrigation water allocation strategies in a changing environment, thus promoting sustainable development of agricultural irrigation systems. • A stochastic multi-objective model is presented for sustainable irrigation. • Mutual contradictions of society, economy, and resources are coordinated. • Effects of uncertainty and climate change on irrigation water allocation are evaluated. • Sustainability of the studied irrigation system is evaluated. • Various managerial insights of irrigation allocation are offered. [ABSTRACT FROM AUTHOR]

This article has studied the optimal scale of manufacturing agglomeration aiming at controlling industrial CO 2 emissions and the role of environmental regulation in China using the main function of panel cointegration and Full Modified Ordinary Least Square(FMOLS) based on the Dynamic Comprehensive Measure (DCM) of intensities of environmental regulation for 28 China's manufacturing subsectors and classification of the manufacturing subsectors according to their intensities of environmental regulations. The empirical results show that: (i) Higher intensity of environmental regulation can spur manufacturing subsectors get more agglomerative economies with less CO 2 emissions. (ii) The relationship between the agglomerative manufacturing subsectors with high and medium intensity of environmental regulation and CO 2 emissions shows inverted U-shaped changing trend. (iii) By contrast, the relationship between the agglomerative manufacturing subsectors with low intensity of environmental regulation and CO 2 emissions more likely presents U-shaped changing trend. (iv) High intensity of environmental regulation aiming at high polluting manufacturing subsectors can make them reach the inflection of CO 2 emissions under high scale of industrial agglomeration. Consequently, the government should take the policy with a general increase in the intensity of environment regulation, and use heterogeneous regulatory instruments according to different manufacturing subsectors so as to increase the emission reduction effect of manufacturing agglomeration. [ABSTRACT FROM AUTHOR]

Efficient irrigation scheduling is crucial for both improving crop production and saving irrigation water use in arid/semi-arid agricultural regions threatened by water shortage and soil salinity. However, irrigation scheduling optimization is hindered by the uncertainties of data and optimization model, and adopting the optimal irrigation scheduling is subject to farmers' acceptance. To effectively tackle these challenges, this paper presents a novel human-machine interactive framework for real-time irrigation scheduling (RIS). The developed modeling framework couples a simulation-optimization model, irrigation farmers, and a data assimilation procedure within the human-machine interactive framework for RIS. The proposed approach is capable of: 1) searching optimal irrigation scheduling through the simulation-optimization model; 2) making actual irrigation decisions based on farmers' experiences, knowledge, behaviors, or optimal solutions; and 3) updating soil water content based on the model simulations and real-time observations at each time period. The RIS is applied to a real-world case in a typical arid agricultural region of China. Based on the comparisons with historical irrigation records and a tradition simulation-optimization model, the proposed RIS can not only achieve higher economic benefit with less irrigation water allocation quotas, but also improve irrigation efficiency. This study contributes to the methodology by integrating computer model, real-time observations and farmers' experiences to optimization modeling framework for supporting sustainable irrigation water management. • A human-machine interactive method is proposed for real-time irrigation scheduling. • Computer model, observation, and farmers' justification are integrated via data assimilation. • The proposed method results in higher profit with less water application than either a conventional optimization model or the history records. [ABSTRACT FROM AUTHOR]

Growing socio-economic development and population poses unprecedented challenges for agriculture in meeting increasing demand of food, water, and energy. Rethinking the future agricultural production to simultaneously safeguard resources security and regulate environmental pollution is essential. Circular agriculture opens up a new path for the high-efficiency and environmental-friendly production. An integrated energy-water-food nexus optimization approach for managing agricultural resources and wastes in line with the principles of sustainable circular agriculture management is lacking. This study therefore proposes an integrated uncertain optimization model to manage agricultural crop-livestock-biogas-crop recycling systems from a cross-sectoral energy-water-food nexus perspective in the changing environment. The aims are to: (1) balance objectives of input reduction, output promotion, ensuring equity, and global warming mitigation; (2) generate sustainable resources allocation strategies based on efficiency and recycling; (3) assess the global warming mitigation potential of the recycling systems from a life cycle perspective; and (4) deal with interactions, complexities, uncertainties, and risks existed in the recycling systems. The proposed model framework is based on a stochastic multi-objective programming, while triangular fuzzy numbers, fuzzy credibility constrained programming, Stewart model, analytic hierarchy process, and opportunity carbon footprint are integrated to enhance its practicability and feasibility. The model is verified through a real-world case study in the Zhanghe Irrigation District, Hubei province, China. Results show that optimal water and land resources allocation solutions are more efficient than current strategies, with water consumption per unit area decreasing by 13.63% and rice production per unit area improving by 22.06%. Paddy field and biogas leakage are two of the largest sources of GHG emission, calling for agronomic and engineering measures to improve farmland management and biogas generation technology. Livestock breeding contributes 10% of the total GHG emission, along with generating 76% of the total biogas, indicating the great significance of manure recycle. Overall, 4.26 × 108 kg CO 2 is reduced in the recycling system, contributed by chemical fertilizer reduction, agricultural wastes recycle, and non-renewable energy replacement. The study offers a potential nexus optimization approach for sustainable management of agricultural recycling systems from a holistic perspective. It can be used as a general model to extend to other agricultural systems suffering from similar resources and environmental crisis. [Display omitted] • Agricultural resources and wastes are managed in the crop-livestock-biogas-crop recycling system. • Cross-sectoral energy-water-food nexus optimization framework is constructed. • Efficient and environmental-friendly water and land resources allocation strategies are generated. • Global warming mitigation potential of the recycling system is assessed. • Interrelations, uncertainties, and risks are handled in the recycling system. [ABSTRACT FROM AUTHOR]

In this study, the accumulation rate of plastic litter was investigated by sampling quadrats placed on the North Island of Qilianyu, and the composition was analyzed and identified to determine its source. The results showed that the annual average accumulation rate of plastic litter on North Island was 0.64 ± 0.32 pieces·m -2 ·month -1 , with a mass accumulation rate of 11.30 ± 7.73 g·m -2 ·month -1 . The accumulation rate of plastic litter was mainly influenced by wind speed and direction, with higher accumulation rates occurring during the southwest monsoon season and tropical cyclones. ATR-FTIR analysis indicated that polyethylene (44 %) and polypropylene (41 %) were the most abundant types of polymers. This study reveals the current status of plastic litter pollution in green turtle nesting grounds on North Island in Qilianyu, which can be used as a reference for management strategies that mitigate plastic litter pollution., Competing Interests: Declaration of competing interest The authors declare no conflicts of interests., (Copyright © 2024. Published by Elsevier Ltd.)

Severe ozone (O 3 ) pollution has been a major air quality issue and affects environmental sustainability in China. Conventional mitigation strategies focusing on reducing volatile organic compounds and nitrogen oxides (NO x ) remain complex and challenging. Here, through field flux measurements and laboratory simulations, we observe substantial nitrous acid (HONO) emissions ( F HONO ) enhanced by nitrogen fertilizer application at an agricultural site. The observed F HONO significantly improves model performance in predicting atmospheric HONO and leads to regional O 3 increases by 37%. We also demonstrate the significant potential of nitrification inhibitors in reducing emissions of reactive nitrogen, including HONO and NO x , by as much as 90%, as well as greenhouse gases like nitrous oxide by up to 60%. Our findings introduce a feasible concept for mitigating O 3 pollution: reducing soil HONO emissions. Hence, this study has important implications for policy decisions related to the control of O 3 pollution and climate change.

Peroxyacetyl nitrate (PAN) is an important photochemical pollutant in the troposphere, whereas long-term measurements are scarce in rural areas in North China Plain (NCP), resulting in unclear seasonal variations and sources of PAN in rural NCP. In this study, we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site. The average concentrations of PAN were 1.10, 0.75, 0.65, and 0.88 ppbv in spring, summer, autumn, and winter, respectively, with a 1-year average of 0.81 ± 0.60 ppbv. Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN, which is an important reason for the low concentration of PAN in summer. We speculate that since the correlation between PAN and O 3 in winter is significantly lower than that in other seasons, the observed regional transport of PAN cannot be ignored in winter. Through budget analysis, regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days, respectively, which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter. The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring. In winter, the transported PAN was mainly from Langfang, Hengshui, and southern Beijing. Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2023. Published by Elsevier B.V.)

Atmospheric ammonia (NH 3 ) plays an important role in secondary inorganic aerosol formation. Understanding the temporal variations, sources, and environmental influences of NH 3 is conducive to better formulate PM 2.5 pollution control strategies for policy-makers. Here, we performed a comprehensive field campaign with the measurements of NH 3 and related parameters at a rural site of the North China Plain (NCP) in winter of 2017. The results showed that residential coal combustion contributed dominantly to NH 3 during the entire observation period, resulting in the obviously high average concentration of NH 3 (31.2 ± 24.6 ppbv). The sensitivity tests of pH-NH x during the three different pollution periods suggested that the rural site was always in the NH x -rich atmosphere where high levels of NH x increased the particle pH inefficiently. Nevertheless, the particle pH still elevated by 1.5-2.2 units at the excessive NH x levels during the three pollution periods. In addition, the HONO/NO 2 ratios were found to correlate linearly with NH 3 concentrations, implying the acceleration effect of NH 3 on HONO production from NO 2 heterogeneous reactions. After considering the NH 3 -enhanced uptake coefficient of NO 2 in the nocturnal HONO budget, the unknown source of HONO could be fully explained. Therefore, more attentions should be given for effective emission control of NH 3 to improve air quality throughout the NCP, especially in the rural areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Particulate nitrate (NO 3 ) has currently become the major component of fine particles in the North China Plain (NCP) during winter haze episodes. However, the contributions of formation pathways to ground NO - ) has currently become the major component of fine particles in the North China Plain (NCP) during winter haze episodes. However, the contributions of formation pathways to ground NO 3 - in the NCP are not fully understood. Herein, the NO 3 - formation pathways were comprehensively investigated based on model simulations combined with two-month field measurements at a rural site in the winter NCP. The results indicated that the nocturnal chemistry of N 2 O 5 hydrolysis aloft could contribute evidently to ground NO 3 - at the rural site during the pollution episodes with high aerosol water contents, achieving the contribution percentages of 25.2-30.4% of the total. In addition to the commonly proposed vertical mixing of breaking nocturnal boundary layer in the early morning, two additional transport pathways (frontal downdrafts and downslope mountain breezes) in the nighttime were found to make higher contributions to ground NO 3 - . Considering the dominant role (69.6-74.8%) of diurnal chemistry in NO 3 - formation, reduction of NO x emissions in the daytime may be an effective control measure for reducing regional NO 3 - in the NCP.

Field measurements of volatile organic compounds (VOCs) were conducted simultaneously at an urban site and one industrial park site in Beijing in summer. The VOCs concentrations were 94.3 ± 157.8 ppbv and 20.7 ± 8.9 ppbv for industrial and urban sites, respectively. Alkanes and aromatics were the major contributors to VOCs in industrial site, while oxygenated volatile organic compounds (OVOCs) contributed most in urban site. The most abundant VOC species were n-pentane and formaldehyde for industrial site and urban site, respectively. The calculated ozone formation potential (OFP) and OH loss rates (L OH ) were 621.1 ± 1491.9 ppbv (industrial site), 102.9 ± 37.3 ppbv (urban site), 22.0 ± 39.0 s -1 (industrial site) and 5.3 ± 2.2 s -1 (urban site), respectively. Based on the positive matrix factorization (PMF) model, solvent utilization I (34.1 %), solvent utilization II (27.9 %), mixture combustion source (19.3 %), OVOCs related source (9.6 %) and biogenic source (9.1 %) were identified in the industrial site, while OVOCs related source (27.8 %), vehicle exhaust (22.1 %), solvent utilization (19.3 %), coal combustion (16.0 %) and biogenic source (14.8 %) were identified in the urban site. The results of O 3 -VOCs-NOx sensitivity indicated that O 3 formation were respectively under the VOC-limited and NOx-limited conditions in Beijing urban and industrial regions. Additionally, aromatics accounted remarkable SOA formation ability both in the two sites, and SOA potentials of xylene, toluene and ethylbenzene as the indicator species for the solvent utilization in industrial site were remarkable higher than those obtained in urban regions. The hazard index values in the industrial and urban sites were 1.72 and 3.39, respectively, suggesting a high non-carcinogenic risks to the exposed population. Formaldehyde had the highest carcinogenic risks in the two sites, and the cumulative carcinogenic risks in the industrial site and urban site were 1.95 × 10 -5 and 1.21 × 10 -5 , respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Gas-phase hydrogen peroxide (H 2 O 2 ) plays an important role in atmospheric chemistry as an indicator of the atmospheric oxidizing capacity. It is also a vital oxidant of sulfur dioxide (SO 2 ) in the aqueous phase, resulting in the formation of acid precipitation and sulfate aerosol. However, sources of H 2 O 2 are not fully understood especially in polluted areas affected by human activities. In this study, we reported some high H 2 O 2 cases observed during one summer and two winter campaigns conducted at a polluted rural site in the North China Plain. Our results showed that agricultural fires led to high H 2 O 2 concentrations up to 9 ppb, indicating biomass burning events contributed substantially to primary H 2 O 2 emission. In addition, elevated H 2 O 2 and O 3 concentrations were measured after fertilization as a consequence of the enhanced atmospheric oxidizing capacity by soil HONO emission. Furthermore, H 2 O 2 exhibited unexpectedly high concentration under high NO x conditions in winter, which are closely related to multiphase reactions in particles involving organic chromophores. Our findings suggest that these special factors (biomass burning, fertilization, and ambient particles), which are not well considered in current models, are significant contributors to H 2 O 2 production, thereby affecting the regional atmospheric oxidizing capacity and the global sulfate aerosol formation., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Atmospheric nitrous acid (HONO) is a dominant precursor of hydroxyl (OH) radicals, and its formation mechanisms are still controversial. Few studies have simultaneously explored effects of different combustion processes on HONO sources. Hereby, synchronous HONO measurement in urban (BJ), suburban (XH) and rural (DBT) areas with different combustion processes is performed in the North China Plain in winter. A box model is utilized to analyze HONO formation mechanisms. HONO concentration is the highest at the DBT site (2.51 ± 1.90 ppb), followed by the XH (2.18 ± 1.95 ppb) and BJ (1.17 ± 1.20 ppb) sites. Vehicle exhaust and coal combustion significantly contribute to nocturnal HONO at urban and rural sites, respectively. During a stagnant pollution period, the NO+OH reaction and combustion emissions are more crucial to HONO in urban and rural areas; meanwhile, the heterogeneous reaction of NO 2 is more significant in suburban areas. Moreover, the production rate of OH from HONO photolysis is about 2 orders of magnitude higher than that from ozone photolysis. Consequently, vehicle exhaust and coal combustion can effectively emit HONO, further causing environmental pollution and health risks. It is necessary to expand the implementation of the clean energy transition policy in China, especially in areas with substantial coal combustion.

Tropospheric ozone (O 3 ) pollution is increasing in the Beijing-Tianjin-Hebei (BTH) region despite a significant decline in atmospheric fine aerosol particles (PM 2.5 ) in recent years. However, the intrinsic reason for the elevation of the regional O 3 is still unclear. In this study, we analyzed the spatio-temporal variations of tropospheric O 3 and relevant pollutants (PM 2.5 , NO 2 , and CO) in the BTH region based on monitoring data from the China Ministry of Ecology and Environment during the period of 2014-2019. The results showed that summertime O 3 concentrations were constant in Beijing (BJ, 0.06 µg/(m 3 •year)) but increased significantly in Tianjin (TJ, 9.09 µg/(m 3 •year)) and Hebei (HB, 6.06 µg/(m 3 •year)). Distinct O 3 trends between Beijing and other cities in BTH could not be attributed to the significant decrease in PM 2.5 (from -5.08 to -6.32 µg/(m 3 •year)) and CO (from -0.053 to -0.090 mg/(m 3 •year)) because their decreasing rates were approximately the same in all the cities. The relatively stable O 3 concentrations during the investigating period in BJ may be attributed to a faster decreasing rate of NO 2 (BJ: -2.55 µg/(m 3 •year); TJ: -1.16 µg/(m 3 •year); HB: -1.34 µg/(m 3 •year)), indicating that the continued reduction of NO x will be an effective mitigation strategy for reducing regional O 3 pollution. Significant positive correlations were found between daily maximum 8 hr average (MDA8) O 3 concentrations and vehicle population and highway freight transportation in HB. Therefore, we speculate that the increase in rural NO x emissions due to the increase in vehicle emissions in the vast rural areas around HB greatly accelerates regional O 3 formation, accounting for the significant increasing trends of O 3 in HB., (Copyright © 2021. Published by Elsevier B.V.)

Carbonyl compounds (carbonyls) play a crucial role in atmospheric chemistry, but their atmospheric sources are not fully identified. Here we show unexpectedly high carbonyl emissions from extensive field returning wheat straw over the North China Plain (NCP). The emission rates of carbonyls exhibit distinct diurnal variations with the noontime peak value of total carbonyls greater than 135 μg∙kg -1 (dry straw weight) ∙h -1 . The carbonyl emission is mainly attributed to biomass abiotic degradation processes that are affected by air temperature and sunlight intensity. Given that the photolysis of carbonyls is the major primary source of RO x radicals in the troposphere, carbonyl emissions would lead to increasing atmospheric oxidants. The mean daytime O 3 concentration over the NCP increases by 12.3% when coupling carbonyl emissions from wheat straw with the current emission inventory through the model simulation. It might be one of the important reasons for the occurrence of the most serious O 3 pollution in June when winter wheat is intensively harvested in the region. Further studies are warranted to explore the influence of field returning wheat straw on regional air quality., Competing Interests: Declaration of competing interest The authors declared that they have no conflicts of interest to this work., (Copyright © 2021 Elsevier B.V. All rights reserved.)

During haze periods in the North China Plain, extremely high NO concentrations have been observed, commonly exceeding 1 ppbv, preventing the classical gas-phase H 2 O 2 formation through HO 2 recombination. Surprisingly, H 2 O 2 mixing ratios of about 1 ppbv were observed repeatedly in winter 2017. Combined field observations and chamber experiments reveal a photochemical in-particle formation of H 2 O 2 , driven by transition metal ions (TMIs) and humic-like substances (HULIS). In chamber experiments, steady-state H 2 O 2 mixing ratios of 116 ± 83 pptv were observed upon the irradiation of TMI- and HULIS-containing particles. Correspondingly, H 2 O 2 formation rates of about 0.2 ppbv h -1 during the initial irradiation periods are consistent with the H 2 O 2 rates observed in the field. A novel chemical mechanism was developed explaining the in-particle H 2 O 2 formation through a sequence of elementary photochemical reactions involving HULIS and TMIs. Dedicated box model studies of measurement periods with relative humidity >50% and PM 2.5  ≥ 75 μg m -3 agree with the observed H 2 O 2 concentrations and time courses. The modeling results suggest about 90% of the particulate sulfate to be produced from the SO 2 reaction with OH and HSO 3 - oxidation by H 2 O 2 . Overall, under high pollution, the H 2 O 2 -caused sulfate formation rate is above 250 ng m -3 h -1 , contributing to the sulfate formation by more than 70%.