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Identification of time spectrum is one of the core issues of the time-domain induced polarization (IP) method, which can be considered as one of the bases for distinguishing various polarized rocks. Fitting the IP data based on the spectrum forward model and obtaining optimal solution of the model parameters is a key step in spectrum identification. However, the suitable forward model should consider the observation conditions, such as the charging time and the time window. The time spectrum identification may be difficult to implement stably due to the lack of objective reference for the optimal solution. Therefore, our purpose is to improve the forward model and implement the spectrum identification for IP data. First, using the Weibull (WB) distribution function as the basis, a time spectrum forward model considering the charging time and observation time window is provided according to the typical measurement mode. Then, based on the WB spectrum model and Barzilai-Borwein gradient optimization, a method for solution of apparent spectral model parameters for spectrum identification is developed. Finally, this method is used to process the IP data from a mine in which the anomalies related to ore-bearing beds are identified based on the processing results. Results obtained demonstrate that the spectrum forward model based on the WB function is feasible in describing the IP data. The limited charging time and a wide observed time window should be considered to realize accurate simulations and description of the time-domain IP data. The essence of the time spectrum identification is to comprehensively reflect the time-varying state of the whole time channel through the spectral model parameters, whereas the decay field ratio of the adjacent time channel can be used as an objective reference. The parameters of the spectrum model characterizing the time-varying state are independent of polarization and resistivity and thus can be directly used for identification of IP anomalies.

Vehicle emissions are regarded as a primary contributor to air pollution and related adverse health impacts. Heavy traffic congestion increases traffic flow and thus produces more O3 precursor emissions, leading to more adverse air quality issues. Although the development of a vehicle emission inventory has received great concern and continuous efforts, limitations still exist. For example, real-time diurnal variations and increases in emission rates due to traffic congestion are not well understood. In this study, we developed a new temporal allocation approach in transportation emissions to investigate the impact on air quality and health burden due to traffic congestion in China in 2020. Both real-time congestion-level data and emission correction factors were considered in the approach. Results show that traffic congestion aggravates air pollution and health burden across China, especially in the urban clusters such as the North China Plain and Sichuan Basin. In these regions, the average annual increases in fine particulate matter (PM2.5) and ozone (O3) could be up to 3.5 µg m−3 and 1.1 ppb, respectively. The excess PM2.5 and O3 attributed to the traffic congestion also induce an additional 20 000 and 5000 premature deaths in China, respectively. In major cities, the increased rate of premature mortality caused by traffic congestion may reach 17.5 %. Therefore, more effective and comprehensive vehicle emission control policies or better planning of the road network should be established to reduce traffic congestion and improve air quality in China.

The dispersive characteristics of high-frequency (≥2 Hz) Rayleigh waves have been widely applied to determine subsurface shear velocity ([Formula: see text]). However, the [Formula: see text] of the high-velocity surface layers (e.g., rigid roads in urban areas) and underlying layers is poorly constrained in the Rayleigh-wave dispersion inversion. Compared to the phase velocity, the Rayleigh-wave horizontal-to-vertical (H/V) ratios of particle motion (i.e., ellipticity) are particularly sensitive to shallow [Formula: see text] structures. Therefore, we have proposed a robust method for obtaining near-surface [Formula: see text] structures by inverting Rayleigh-wave dispersion and H/V data. Initially, we separate the fundamental-mode Rayleigh waves from the active-seismic records using a high-resolution linear Radon transformation method. Then, we extract the high-frequency H/V and interstation phase traveltimes from the separated fundamental mode using deconvolution interferometry and the frequency-time analysis method. Based on the phase traveltimes, we calculate the phase velocity dispersion using ray-based tomography. Finally, we perform the joint inversion of dispersion and H/V data to obtain the [Formula: see text] structure. According to the inversion results of synthetic and field data, the accuracy of the [Formula: see text] in the rigid surface layer and underlying layers is considerably improved. We find that the joint inversion of Rayleigh-wave phase velocity dispersion and H/V data from surface-wave surveys is a useful tool for accurately determining the complex shallow [Formula: see text] structures.

The traffic control policies, including "Odd and Even" (OAE) and "One Day Per Week" (ODPW), were adopted in Zhengzhou, China. In this study, we use the bottom-up policy evaluation framework to capture the temporal-spatial characteristics of traffic conditions and vehicle emissions under various traffic restriction scenarios. Moreover, we use the street-scale simulation model to evaluate the effectiveness of improving air quality. Results showed that the improvements in traffic conditions led to the emission decrease by about 28.3 % for carbon monoxide (CO), 16.2 % for nitrogen oxide (NOx), 21.3 % for particulate matter (PM

Marine magnetic surveys over oceanic ridge regions are of great interest for investigations of structure and evolution of oceanic crust, and have played a key role in developing the theory of plate tectonics (Dyment, 1993; Maus et al, 2007; Vine and Matthews, 1963). In this study, we propose an interpolation approach based on the dual-layer equivalent source model for the generation of a magnetic anomaly map based on sparse survey line data over oceanic ridge areas. In this approach, information from an ocean crust age model is utilized as constraint for the inversion procedure. The constraints can affect the magnetization distribution of equivalent sources following crust age. The results of synthetic tests show that the obtained magnetic anomalies have higher accuracy than those obtained by other interpolation methods. Meanwhile, considering the unclear on the true magnetization directions of sources and the background field in the synthetic model, well interpolation result can still be obtained. We applied the approach to magnetic data obtained from five survey lines east of the Southeast Indian Ridge. This prediction result is useful to improve the lithospheric magnetic field models WDMAMv2 and EMAG2v3, in the terms of spatial resolution and the consistency with observed data.

The rapid growth of the vehicle population was regarded as an important factor that contributed to the urban air pollution in China during the past decades. We used Tianjin, a typical megacity facing vehicle pollution problems, as the study domain to investigate a comprehensive estimation of vehicle emissions, including carbon monoxide (CO), volatile organic compounds (VOCs), nitrogen oxides (NOx), inhalable particles (PM10), carbon dioxide (CO2) and sulphur dioxide (SO2), from 2000 to 2030. The Computer Programme to calculate Emissions from Road Transport (COPERT) model was used to simulate the vehicle emission factors. Historical simulations show that the total emissions of CO, VOCs, NOx, PM10, CO2, and SO2 changed from 545.1 Gg, 70.04 Gg, 60.19 Gg, 6.57 Gg, 6.82 Tg and 12.88 Gg to 259.11 Gg, 34.01 Gg, 55.14 Gg, 3.42 Gg, 25.30 Tg and 0.16 Gg from 2000 to 2016, respectively. Passenger cars (PC) and light-duty vehicles (LDV) were the main contributors to the CO and VOCs emissions. Heavy-duty trucks (HDT) and buses (BUS) were the important contributors to NOx and PM10. PC was the major contributor to CO2 and SO2. With respect to the future, four Single Control Policy Scenarios (SCPS), including Passenger car Population Regulation (PPR), Emission Standard Updating (ESU), Public Transportation Promotion (PTP) and Electric Vehicle Popularity (EVP), and Integrated Scenarios (IS), were assembled to describe the impact of future policies on vehicle pollution from 2017 to 2030. Among all SCPS, the results show that the ESU is the more effective policy to control emissions of CO, NOx and PM10, while PPR is the more effective way to reduce emissions of VOCs, CO2, and SO2.

We have developed a case study on the use of constrained inversion of magnetic data for recovering ore bodies quantitatively in the Macheng iron deposit, China. The inversion is constrained by the structural orientation and the borehole lithology in the presence of high magnetic susceptibility and strong remanent magnetization. Either the self-demagnetization effect caused by high susceptibility or strong remanent magnetization would lead to an unknown total magnetization direction. Here, we chose inversion of amplitude data that indicate low sensitivity to the direction of magnetization of the sources when constructing the underground model of effective susceptibility. To reduce the errors that arise when treating the total-field anomaly as the projection of an anomalous field vector in the direction of the geomagnetic reference field, we develop an equivalent source technique to calculate the amplitude data from the total-field anomaly. This equivalent source technique is based on the acquisition of the total-field anomaly, which uses the total-field intensity minus the magnitude of the reference field. We first design a synthetic model from a simplified real case to test the new approach, involving the amplitude data calculation and the constrained amplitude inversion. Then, we apply this approach to the real data. The results indicate that the structural orientation and borehole susceptibility bounds are compatible with each other and are able to improve the quality of the recovered model to obtain the distribution of ore bodies quantitatively and effectively.

Vehicular refueling emission is a potential source of urban atmospheric volatile organic compounds (VOCs) that is not well understood and controlled. China 6 vehicles have been equipped with the onboard refueling vapor recovery (ORVR) system to cut down refueling emissions, while the emission characteristics and reduction effectiveness are rarely reported. In this study, we conducted laboratory tests to measure the refueling emissions from ten China 6 vehicles and three China 5 vehicles (refueling-emission-uncontrolled, REU) and developed an inventory in a typical middle-sized Chinese city (Langfang) to explore the emission reduction resulted from relevant policies. Compared with headspace vapor and refueling vapor from REU vehicles, the emission profiles for China 6 vehicles are consist of considerably higher proportions of small alkanes and alkenes (C2-C3) and lower proportions of C6-C8 hydrocarbons. Such differences indicate that the headspace vapor profiles are incapable of representing the refueling emission for China 6 vehicles. The market-share-weighting emission factors (EFs) of total hydrocarbons (THCs) and total VOCs for China 6 vehicles are 11.2 mg/L and 6.4 mg/L, respectively, corresponding to control efficiency of approximately 98.8% compared with the REU vehicles. Based on the real-world EFs and the fuel consumption in Langfang, a refueling emission inventory with high spatiotemporal resolution is developed. The total refueling emission of THCs in Langfang is approximately 190.6 tons in 2018 and will likely decline to 25.0 tons in 2035. The implementation of the ORVR will contribute to 90% of the refueling emission reduction in 2035.

Vehicular evaporative emission is a major source of atmospheric volatile organic compounds (VOCs), while quantification and characterization of the evaporative emission in China, particularly for the vehicles meeting the latest emission standards, are rarely reported. In this study, we performed evaporative emission experiments in a sealed housing evaporative determination (SHED) using eleven new and in-use light-duty gasoline vehicles to investigate the evaporative VOCs emission from the China 5 and China 6 vehicles and unravel the deterioration of evaporation control system of in-use ones. The total hydrocarbon (THC) emission factors (EFs) of 24-h diurnal breathing loss from the new China 6, new China 5 and in-use China 5 vehicles are 0.25, 0.81 and 5.27 g/d respectively. Compared with headspace vapor, the emission profiles of both hot soak loss (HSL) and diurnal breathing loss (DBL) from all new tested vehicles contain more C7–C9 aromatics, particularly for the China 6 vehicles. C4–C5 alkanes and C7–C9 aromatics account for most of total VOCs mass for all China 5 vehicles, while emissions from the China 6 vehicles exhibit no strongly prevailing species for both HSL and DBL emission. Typical ratios like normalized ratios of benzene, toluene and ethylbenzene can be used to distinguish evaporative emission from vehicular exhaust. Ozone formation potentials (OFPs) of the in-use China 5 vehicles are 5.35 and 7.16 times higher than that of China 5 new ones in DBL and HSL experiments respectively. Secondary organic aerosol formation potential of all tests ranged from 17.30 to 29.76, with aromatics contributing the largest proportion (over 90.0%). With the implementation of China 6's standard, the evaporative THC emission in China may peak in 2022 and will be cut down by 76% until 2030. Also, the underestimation of evaporative emission was estimated when neglecting the difference of EFs between new and in-use vehicles.

Vehicle emissions have been investigated in many developed areas; however, little attention has been paid to underdeveloped regions. This study conducts a comprehensive investigation on the vehicle emissions in Inner Mongolia, an area with low economic development in China. In 2019, total vehicle emissions of carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), and inhalable particles (PM10) are 211.04, 100.83, 38.96, and 4.43 Gg, respectively. Gasoline vehicles are the main contributors of CO and VOCs, while diesel vehicles contribute more NOx and PM10. Vehicle emissions are various in different regions and times. The variations in vehicle emissions are forecasted from 2020 to 2025 under the business-as-usual scenario (BAU), controls on in-use vehicles (CIV), vehicle population constraint (VPC), public transportation improvement (PTI), new energy vehicle promotion (NEV), and integrated scenario (IS). In addition, reduction effects, cost of implementation and energy consumption are analyzed for all the scenarios. At present, the CIV and VPC are suggested to be adopted primarily in Inner Mongolia, while other policies need to be postponed according to the analysis results.

The vehicle emission inventory is used to describe air pollutants from vehicles quantitatively. Many emission inventories have been developed using the top-down method in China; however, most have a low temporal-spatial resolution. This study utilized the top-down method to develop a vehicle emission inventory with high temporal-spatial resolution in Tianjin, China, a typical megacity experiencing severe vehicle pollution. The relationship between vehicle age and annual average vehicle kilometers travelled (VKT) was investigated by introducing the age-VKT curve, which indicated that the VKT decreased when vehicles get older. The emission estimation showed that light-duty passenger vehicles were the major contributors of carbon monoxide and volatile organic compounds, while heavy-duty passenger vehicles and heavy-duty trucks contributed significantly to nitrogen oxides and fine inhalable particles. China III standard vehicles were the main contributors to all pollutants. High-resolution gridded emissions were obtained using a practical allocation method, which showed that the spatial distributions differed slightly for each pollutant and the emissions changed significantly in a 24-h period. This study presented a comprehensive approach to developing a high-resolution emission inventory that can be utilized to assist in pollution control policy formulation.

Crop residue open burning represents an important source of biomass burning. Shandong is a large agricultural province in China. An emission inventory of crop residue open burning was established in Shandong Province for 2014 based on emission factors (EFs) and activity data (include: crop production, residue-to-production ratios, fraction of straw burned in the field, fraction of dry matter in straw and combustion efficiency for the various crops). The latest local residue-to-production ratios, fraction of straw burned in the field and EFs of each crop were used in this paper to improve the accuracy of our inventory. The results showed that the total emissions of sulfur dioxide (SO 2 ), nitrogen oxide (NO X ), ammonia (NH 3 ), methane (CH 4 ), non-methane volatile organic compounds (NMVOCs), fine particulate matter (PM 2.5 ), elemental carbon (EC) and organic carbon (OC) in Shandong Province for 2014 were 3.48, 25.37, 5.41, 25.9, 60.37, 379.19, 62.3, 2.86 and 21.09 kt, respectively; corn stalks represented the largest contribution of different pollutants. The emissions were spatially allocated into grid cells with a resolution of 0.1° × 0.1° by Geographic Information System (GIS) using both cultivated land use area data and fire counts as spatial surrogates. The cities with the highest emissions were Linyi, Qingdao, Binzhou and Dezhou, which have a high crop yield and densely rural population. The emissions were temporally concentrated from April to July. The uncertainties in the estimated emissions from crop residue burned in the open field were quantified by a Monte Carlo simulation.

Non-uniqueness is a problem encountered while imaging subsurface susceptibility by inverting magnetic field surveys. We propose a novel method to construct velocity-susceptibility initial models using Vp together with the Vp/Vs ratio from seismic tomography to improve the model which satisfies more information and better identifies locations of high-susceptibility materials. For comparison, two recovered susceptibility structures are derived from two distinct initials (homogeneous and velocity-susceptibility) models through the standard inversion process. Two profiles with intense undulation of magnetic anomalies over sedimentary areas in central-west Taiwan and complex geological structures at the rim of the subduction zone in northeast Taiwan are used as examples to compare the results of the initial models. The inversion results suggest that the susceptibility structures from both models agree in terms of the location of the fault zones, specifically at depth 10 km. Consequently, the initial model with velocity constraints lowers the non-uniqueness associated with the inversion of magnetic anomalies.

In surface-wave methods, horizontal resolution can be defined as the ability to distinguish anomalous objects that are laterally displaced from each other. The horizontal length of a recognizable geological anomalous body is measured by the lateral variation of shear (S)-wave velocity. Multichannel analysis of surface waves (MASW) is an efficient tool to determine near-surface S-wave velocities. The acquisition of the MASW method involves the same source-receiver configuration moved successively by a fixed distance interval (a few to several stations) along a linear survey line, which is called a roll-along acquisition geometry. A pseudo-2D S-wave velocity section is constructed by aligning 1D models, and each inverted 1D S-wave velocity model reflects the vertical S-wave velocity variation at the midpoint of each geophone spread. Although the MASW method can improve the horizontal resolution of S-wave velocity sections to some degree, the amount of fieldwork is increased by the roll-along acquisition geometry. We propose surface-wave tomography method to investigate horizontal resolution of surface-wave exploration. Phase-velocity dispersion curves are calculated by a pair of traces within a multichannel record through cross-correlation combined with a phase-shift scanning method. Then with the utilization of travel-time tomography, we can obtain high resolution pure-path dispersion curves with diverse sizes of grids at different frequencies. Finally, the pseudo-2D S-wave velocity structure is reconstructed by inverting the pure-path dispersion curves. Travel-time tomography of surface waves can extract accurate dispersion curves from a record with a short receiver spacing, and it can effectively enhance the ability of random noise immunity. Synthetic tests and a real-world example have indicated that travel-time tomography has a great potential for improving the horizontal resolution of surface waves using multi-channel analysis.

Vehicle emissions are regarded as an important contributor to urban air pollution in China and most previous studies focused on megacities. However, the vehicle pollution in middle-sized cities becomes more severe due to the increasing vehicle population (VP) and lagged control policy. This study takes Langfang, a typical middle-sized city bordered by two megacities (Beijing and Tianjin), as the target domain to investigate vehicle emissions. The speed correction curves (SCC) are introduced to improve the vehicle emission factors (EF) simulation in official technical guidelines on emission inventory (GEI). A multi-year vehicle emission inventory (from 2011 to 2025) is developed in Langfang. From 2011 to 2017, the total vehicle emissions in Langfang decrease for carbon monoxide (CO), but increase for volatile organic compounds (VOCs), nitrogen oxides (NOx), and inhalable particles (PM10), respectively. From 2018 to 2025, the emissions would increase more rapidly in Langfang than in Beijing and Tianjin, indicating the middle-sized cities may become a significant contributor to air pollution in China. Four possible control policies, including VP constrained (VPC), public transportation promotion (PTP), new energy vehicles promotion (NEP), and freight transportation structure optimization (FTO) are evaluated. The most significant emissions reductions are observed under the FTO for CO, NOx, and PM10, and under the VPC for VOCs. The spatial distributions of vehicle emissions show a high order of heterogeneity, indicating that local conditions should be considered in policy formulation in addition to national consistency. More comprehensive policies should be implemented to mitigate the vehicle pollution in middle-sized cities. Keywords: Vehicle emissions, Emission inventory, Emission factors, Policy evaluation, Spatial distribution

Vehicular emission is a key contributor to ambient volatile organic compounds (VOCs) and NOx in Chinese megacities. However, the information of real-world emission factors (EFs) for a typical urban fleet is still limited, hindering the development of a more reliable emission inventory in China. Based on a more-than-two-week (August 8–24, 2017) tunnel test in urban Tianjin in northern China, and on the use of a statistical regression model, the Positive Matrix Factorization (PMF) receptor model, and the Calculate Emissions from Road Transport (COPERT) IV model, characteristics of vehicular VOCs-NOx-CO emissions were analyzed systematically. The fleet-average EFs (pollutant: downslope, upslope, and overall in mg km−1 veh−1) were estimated respectively as follows: (NO: 61.92 ± 72.46, 158.58 ± 73.48, 97.52 ± 69.84), (NO2: 16.52 ± 11.49, 23.98 ± 20.14, 15.86 ± 9.38), (NOx: 79.45 ± 78.43, 181.22 ± 88.29, 116.56 ± 77.61), and (CO: 269.96 ± 342.38, 577.76 ± 382.22, 344.67 ± 250.01). The EFs of NO-NO2-NOx and CO from heavy-duty vehicles (or diesel vehicles) were differentiated from light-duty vehicles (or gasoline vehicles). The ratios (v / v) of NO2 to NOx in the primary vehicular exhaust were approximately 0.18 ± 0.09, 0.10 ± 0.22 and 0.10 ± 0.05 for downslope, upslope, and the entire tunnel, respectively. The fleet-average EF of the 99-target non-methane VOCs (NMVOCs) was 40.56 ± 12.18 mg km−1 veh−1, lower than the previous studies in China. The BTEX (benzene, toluene, ethylbenzene, p-xylene, m-xylene and o-xylene) levels decreased by approximately 79 % when emission standards increased from China I to China V. The source profiles of NMVOCs from the tailpipe and evaporative emissions were resolved by the PMF model. The evaporative emissions accounted for nearly one-half of the total vehicular VOC emissions, indicating that evaporative and tailpipe emissions contributed equally to VOC emissions. The relative contributions of evaporative NMVOC emissions to total vehicular NMVOC emissions are temperature-dependent with the average increasing ratio of 7.55 % °C−1. The primary emission ratio (ER, m / m) of VOCs / NOx was approximately 2.04, suggesting that vehicular NOx and VOCs can be co-emitted with a proper ER. According to the vehicular ERs of VOCs / NOx in Tianjin (2000–2016) and China (2010–2030), as even more stringent emission standards are implemented in the future, the O3 chemical regimes were likely to be VOCs-limited (i.e., 8 : 1 threshold) for cities or regions where VOCs and NOx emissions are dominated by vehicular exhaust. Our study enriched the database on the fleet-average emission factors of on-road vehicles for emission inventory, air quality modeling, and health effects studies, provided implications for following O3 control in China from the view of primary emission, and highlighted the importance of further control of evaporative emissions.

Heavy metal pollution is becoming a growing global problem in Jinan, tree is a useful bio indicators which record annual impressions of the pollution environment. With the economic development in 80s to 90s, higher value of Pb, Cd, Mn and Cr contamination in tree rings are close relate to pollution emissions of a large number of serious pollution small and medium-sized enterprise, last century, higher value of Pb contamination of JQ sample point, near the outer ring road, is closely related to rapidly increased traffic capacity, At the beginning of this century, As nutrient element of plant, Mn, Ca are higher in juvenile stage and no obvious fluctuation in other stage because of young-age effect of trees, After correlation analysis and principal component analysis, found that coal, iron and steel smelting, cement production and motor vehicle exhaust emission are main contributor of heavy metal pollution both in SZ point and JQ point.