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Harmful algal blooms have raised great concerns due to their adverse effects on aquatic ecosystems and human health. Recently, visible light-driven (VLD) photocatalysis has attracted attention for algae inactivation owing to its unique characteristics of low cost, mechanical stability, and excellent removal efficiency. However, the low utilization of visible light and the high complexation rate of electron-hole (e

Measurement and analysis of CO

Net primary productivity (NPP) and carbon use efficiency (CUE) are common ecological indicators for assessing the terrestrial carbon cycle. However, despite their widespread use, considerable uncertainties exist toward the response patterns of NPP and CUE to climate variability along an aridity gradient, especially for grassland ecosystems. The aridity index (AI) was calculated in this study to specify arid-humid zones across the global grassland ecosystem. The dynamics of grassland NPP, CUE, and their dependence on climate under different AI levels from 2000 to 2013 were investigated. Results showed that the NPP and CUE of grasslands demonstrated a slightly increasing trend with regional increasing precipitation in most AI zones, except for arid regions (AR) from 2000 to 2013. The NPP and CUE of grasslands exhibited a remarkable spatial heterogeneity in different AI zones. High NPP values mainly occurred in the dry and sub-humid (DSH) and humid (HU) regions of Southern Hemisphere with warm and wet climate. High CUE values were mostly found in the HU of the Northern Hemisphere with cold and wet climate. In addition, low NPP and CUE values were observed in most parts of AR and semi-AR (SAR) with hot and dry climate. Overall, the NPP and CUE of grasslands were significantly affected by precipitation at the global scale. Specifically, grassland NPP was positively correlated with the mean annual precipitation (MAP) in SAR and AR, but negatively related with the MAP in the HU region. The positive correlation between NPP and mean annual temperature (MAT) was found only for HU regions. Grassland CUE indicated a positive relation with MAP, but a negative relation was observed with MAT in all AI zones. The correlation coefficients between CUE and MAP decreased from AR to HU regions. This finding indicated that grassland CUE was highly sensitive to precipitation in dry areas, but this relationship weakened in HU ecosystems.

Source-specific health risks of PM2.5-bound metals were analyzed for emission control by integrating source apportionment with health risk assessments of residents affected via inhalation pathways. A total of 218 daily PM2.5 samples were collected in 2016 in the central urban district of Beijing, China. Analyses showed that the mean annual concentrations of total heavy metals (THMs) and PM2.5 were 0.39 and 104.37 μg m−3, respectively. The heating season had significantly higher concentrations of THMs and PM2.5 (0.61, 134 μg m−3) than the non-heating season (0.27, 88.1 μg m−3) (p

Although many studies have investigated the toxic effects of polystyrene microplastics (PS-MPs), toxicity of natural aged of PS-MPs to soil organisms remains unclear. The photodegradation of virgin PS-MPs under UV irradiation was investigated, and reproductive toxicity of pristine and UV-photodegraded PS-MPs at environmental concentrations (0.1-100 μg/L) was examined to Caenorhabditis elegans. Using brood size and egg ejection rate as endpoints, acute exposure to aged PS-MPs resulted in more severe reproductive toxicity than pristine PS-MPs. Exposure to 100 μg/L aged PS-MPs significantly increased the number of HUS-1::GFP foci and the expression of genes required for DNA damage, such as clk-2, cep-1, and egl-1, suggesting induction of DNA damage. Additionally, the number of cell corpses and apoptosis-related gene expression (e.g., ced-3, ced-4, and ced-9) were significantly altered, indicating induction of apoptosis. Germline apoptosis induced by aged PS-MPs was altered in egl-1, hus-1, cep-1, ced-3, ced-4, and ced-9 mutants. Thus, the reproductive toxicity of aged PS-MPs may be due to DNA damage-induced cell apoptosis, and the HUS-1-CEP-1-EGL-1-CED-9-CED-4-CED-3 signalling pathway is involved in regulating cell apoptosis in nematodes.

The accurate source tracing of volatile organic compounds (VOCs) in complicated source environments is challenging to perform, as similar pollutants may be emitted from different chemical processes. An emission profile-based source tracing method, based on comparing similarities between source profiles and ambient air profiles, was evaluated, and was found to improve the tracing efficiency. Emission profiles were acquired from a typical chemical industrial park in the Yangtze River Delta, China. A total of 30 process-based emission profiles comprising 107 VOC species were investigated and similarities among them were calculated. This analysis demonstrated that the similarities between emissions from various chemical processes are universal. Source tracing was then conducted for six air pollution episodes, based on the emission profile-based source tracing method combined with wind speed and direction data. The results showed that the proposed approach represents an efficient method for source tracing. This study enriches the database of source profiles for petroleum-related industries. The emission profiles from references and the air pollution episodes augment the emission profile database, especially under abnormal emission conditions. The database will more effectively serve future source-tracing cases, creating a virtuous circle that improves source tracing efficiency.

Peatlands located at the northern edge of the East Asian monsoon (EAM) are well placed to provide a terrestrial record of past climate and hydrological changes for this globally sensitive region. Here we present a middle to late Holocene, diatom-derived water-table records from a peatland in the Greater Hinggan Mountains, northeastern China. An age-depth model was achieved through AMS14C dating and Bayesian piece-wise linear accumulation modelling. The diatom-based water-table reconstructions show that the peatland water-table rose from 5100 to 3500 cal. yr BP, but fell approximately 3500 cal. yr BP. From about 2800 to 1500 cal. yr BP, the peatland water-table stabilized. After about 1500 cal. yr BP, several rapid hydrological shifts, which correspond with global climate anomalies such as ice-rafted debris (IRD) events, were registered in the reconstructed water-tables. Compared with other paleoclimate records in East Asia, the general trend of peatland water-table fluctuations follows the variations in the East Asian summer monsoon (EASM) intensity. Spectrum analysis of the water-table profile yielded a statistically significant periodicity of 470-year that may be related to the “~500-year” inherent solar irradiation cycles. In addition, positive correlation between the peatland water-table levels and cosmic-isotope-reconstructed sunspot numbers underscores the role of the sun in regulating hydrological processes in the EASM margin area. The data suggest that the regional climate and hydrological variations at the EASM margin were first triggered by changes in solar output, but may have been amplified by interactions with oceanic and atmospheric circulations.

Regions at high latitudes and high altitudes are undergoing a more pronounced winter warming than spring warming, and such asymmetric warming will affect chilling and forcing processes and thus the spring phenology of plants. We analyzed winter chilling and spring forcing accumulation in relation to the spring phenology of three tree species (Ulmus pumila, Populus simonii, and Syringa oblata) growing in a cold region (CR) compared with trees in a warmer reference region (WR), using the Dynamic Model and the Growing Degree Hour (GDH) model. We tested that forcing rather than chilling affects the spring phenology of trees in CR (hypothesis I), and that trees in CR have both lower mean chilling and forcing temperature and thus longer accumulation periods than trees in WR (hypothesis II). The modeling results confirmed that chilling and forcing occur simultaneously during the early spring when temperature gradually increases. In line with our hypotheses, forcing played a crucial role in spring phenology in CR, but chilling and forcing combined to determine spring phenology in WR. The temperature during the chilling and forcing periods was lower and the accumulation period started earlier and ended later in CR than in WR. Moreover, the chilling accumulation was broken into two periods by the low deep winter temperature in CR, and that interruption will be removed by future strong winter warming. Future asymmetric warming, with a stronger temperature increase in winter than in spring, could decrease the forcing accumulation effects and increase the chilling effects on the spring phenology of plants in CR. This change in the balance between chilling and forcing will lead to a shift in plant phenology, which will further have major impacts on biogeochemical cycles and on ecosystem functions and services.

To mitigate the grassland degradation in the Mongolian Plateau (MP), both China and Mongolia governments have carried out a series of new policies and ecological projects. However, the effect of such restoration measures on the productivity of grassland in the MP under different political systems remains unclear. Here we study the effects of land use and land cover change, human activities and climate change on the net primary productivity (NPP) of grassland in Mongolia (MG) and Inner Mongolia (IM) from 2001 to 2014. Results showed that the area of grassland increased in both MG and IM, accounted for 4.45 × 104 and 10.31 × 104 km2, respectively. The extended grassland contributed 4.34 × 108 Gg C (Gg = 109 g) to the total NPP, while the loss of grassland led to a decrease of 0.19 × 108 Gg C. The total NPP of grasslands in 2014 increased about 17.88% and 30.49% respectively in MG and IM since 2001. Specifically, IM exhibited a higher increase in land converted NPP than MG. The area of grassland restoration in IM and MG accounted for 90.21% and 81.45%, respectively, indicating that the grassland of the MP was restored. Although human activity was the dominant factor on grassland degradation, which was accounted for 9.79% and 18.55% in IM and MG, it has a positive effect on most of the grassland NPP in the MP. Overall, policy measures and ecological projects in IM brought a more positive effect compared with that in MG.

Traditional chemical precipitation of phosphates from wastewater is somewhat inefficient because it produces some ultrafine hydroxyapatite particles that are difficult to settle. In this study, magnetic seeds with a core–shell structure were prepared by sulfation roasting for magnetic flocculation of those fine particles. Zeta potential measurements show that the hydroxyapatite particles are positively charged at pH 10, whereas the magnetic seeds are negatively charged. The Derjaguin–Landau–Verwey–Overbeek calculation indicates that the van der Waals force between the magnetic seeds and hydroxyapatite particles is always attractive. Moreover, the electrostatic attraction also contributes to aggregation of the magnetic seeds and hydroxyapatite particles. Orthogonal experiments show that the main factor affecting the magnetic flocculation is the dosage of magnetic seeds, and polymeric ferric sulfate also plays an important role. Under the optimal magnetic flocculation experimental conditions, the turbidity of wastewater after magnetic separation was only 16.388 NTU, contributing to the removal of phosphate contaminants. Therefore, magnetic flocculation and magnetic separation may provide an alternative solution for efficient purification of phosphate-containing wastewater.