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Forests and grasslands play an important role in carbon cycling. They not only absorb CO2 from the air through vegetation biomass and soil carbon sinks, but also reduce and control the horizontal transport of soil carbon (i.e., reinforcing soil carbon storage via soil conservation), thus avoiding erosion-induced CO2 emissions. In this study, vegetation biomass and soil carbon sinks, soil carbon reinforcement and reduced carbon emissions via soil conservation by forests and grasslands were quantified on the scale of the whole of China. The analysis was based on the distribution of biomass and the soil carbon pool and soil erosion rates derived from national surveys, as well as carbon density values from field surveys and literature. In 2021, forests and grasslands in China generated 394.18 Mt C/year (y) of steady-state carbon sinks through vertical biomass and soil absorption. The biomass carbon sinks of grasslands, and those of leaves, twigs, flowers and fruits of the forests, were not taken into account when quantifying the stable biomass sink, because they can become net producers of CO2 due to seasonal withering and carryover, or they can form soil organic carbon as potential soil carbon sinks. The amount of horizontal soil carbon reinforcement in China's forests and grasslands in 2021 was 20.31 Mt C/y, which was positively correlated with the reduction in the water erosion area; consequently, vertical emissions of approximately 14.89–29.78 Mt of CO2 into the atmosphere were avoided. Overall, in 2021, China's forests and grasslands absorbed atmospheric CO2 and reduced emissions by 1.46–1.47 Gt CO2/y, equivalent to approximately 13% of China's annual fossil CO2 emissions. This study demonstrates the fact that the adoption of forest and grassland measures sequesters carbon in soil and biota and reduces the risks of CO2 emissions by both vertical and horizontal paths, which is important for achieving carbon neutrality and mitigating climate change. [ABSTRACT FROM AUTHOR]

The carbon balance of the global ecosystems is significantly influenced by the soil organic carbon (SOC) pool in China's terrestrial ecosystems. Nevertheless, the current understanding of the main controlling factors of SOC in different ecosystems and their discrepancies is limited. The goal of this research was to better understand the human and environmental variables affecting SOC in China's terrestrial ecosystems. We designed a conceptual framework using 2674 samples collected from four ecosystems (grasslands, shrublands, wetlands, and croplands) in China during the 2000–2014 period, combining geodetector and multiple regression (MR) approaches to investigate the effects of environmental conditions, human activity, and their interplay on surface SOC (0–20 cm). Results showed that there were large discrepancies in the strength of influencing factors among different ecosystems. Total nitrogen (TN), mean annual temperature (MAT), and bulk density (BD) were the major factors influencing SOC in grasslands. BD, TN, and pH dominated in shrublands. For wetlands, SOC stocks were primarily attributed to maximum temperature (TMMX), MAT, and potential evapotranspiration (PET). Croplands are predominantly controlled by minimum temperature (TMMN), MAT, and TN. These results highlight that natural factors, particularly climatic and soil characteristics, were the dominant factors controlling SOC stocks in China's terrestrial ecosystems. This work also highlights that the interaction of two influencing factors, especially, pairs of soil characteristics factors, pairs of climate and soil characteristics factors, can well explain the drivers of SOC on the surface soil in China. Our study emphasizes the spatial heterogeneity of the factors that influence SOC in terrestrial ecosystems, enhancing knowledge of SOC at the national level, and providing the guideline for devising better policy to improve C sequestration and mitigate climate changes. [ABSTRACT FROM AUTHOR]

Rice has always been one of the major food sources for human beings, and the monitoring and planning of cultivation areas to maintain food security and achieve sustainable development is critical for this crop. Traditional manual ground survey methods have been recognized as being laborious, while remote-sensing technology can perform the accurate mapping of paddy rice due to its unique data acquisition capabilities. The recently emerged Google Earth Engine (GEE) cloud-computing platform was found to be capable of storing and computing the resources required for the rapid processing of massive quantities of remote-sensing data, thereby revolutionizing traditional analysis patterns and offering unique advantages for large-scale crop mapping. Since the phenology of paddy rice depends on local climatic conditions, and considering the vast expanse of China with its outstanding geospatial heterogeneity, a zoning strategy was proposed in this study to separate the monsoon climate zone of China into two regions based on the Qinling Mountain–Huaihe River Line (Q-H Line), while discrepant basic data and algorithms have been adopted to separately map mid-season rice nationwide. For the northern regions, optical indices have been calculated based on Sentinel-2 images, growth spectral profiles have been constructed to identify phenological periods, and rice was mapped using One-Class Support Vector Machine (OCSVM); for the southern regions, microwave sequences have been constructed based on Sentinel-1 images, and rice was mapped using Random Forest (RF). By applying this methodological system, mid-season rice at 10 m spatial resolution was mapped on the GEE for the entire Chinese monsoon region in 2021. According to the accuracy evaluation coefficients and publicly released local statistical yearbook data, the relative error of the mapped areas in each province was limited to 10%, and the overall accuracy exceeded 85%. The results could indicate that mid-season rice can be mapped more accurately and efficiently on a China-wide scale with relatively few samples based on the proposed zoning strategy and mapping methods. By adjusting the parameters, the time interval for mapping could also be further extended. The powerful cloud-computing competence of the GEE platform was used to map rice on a large spatial scale, and the results can help governments to ascertain the distribution of mid-season rice across the country in a short-term period, which would be well suited to meeting the increasingly efficient and fine-grained decision-making and management requirements. [ABSTRACT FROM AUTHOR]

Continuous and extensive monitoring of forest height is essential for estimating forest above-ground biomass and predicting the ability of forests to absorb CO2. In particular, forest height at the national scale is an important indicator reflecting the national forestry economic construction, environmental governance, and ecological balance. However, the lack of inventory data restricts large-scale monitoring of forest height to some extent. Conducting manual surveys of forest height for large-scale areas would be labor-intensive and time-consuming. The successful launch of the new generation of spaceborne light detection and ranging (LiDAR) (The Ice, Cloud, and Land Elevation Satellite-2/the Advanced Topographic Laser Altimeter System, ICESat-2/ATLAS) has brought new opportunities for national-scale forestry resource surveys. This paper explores a method to survey national forest canopy height from the new generation of ICESat-2/ATLAS data. In view of the sparse sampling and little overlap between repeated spaceborne LiDAR data, a strategy for assessing the overall change of canopy height for large scales is provided. Some spatially continuous ancillary data were used to assist ICESat-2/ATLAS data to generate a wall-to-wall (spatially continuous) forest canopy height map in China by using the machine learning approach and then quantifying the analysis of forest canopy height in various provinces. The results show that there is a good correlation between the model forest height and the verification data, with a root mean squared error (RMSE) of 3.30 m and a coefficient of determination (R2) of 0.87. This indicates that the method for retrieving national forest canopy height is reliable. There are some limitations in areas with lower vegetation coverage or complex topography which need additional filtering or terrain correction to achieve higher accuracy in measuring forest canopy height. Our analysis suggests that ICESat-2/ATLAS data can achieve the retrieval of national forest height at an overall level, and it would be feasible to use ICESAT-2/ATLAS products to estimate forest canopy height change for large-scale areas. [ABSTRACT FROM AUTHOR]

Certain neonicotinoid metabolites (mNEOs) are causing widespread concern because they are equally or even more toxic than the parent NEOs. Currently, there is limited information on the distribution of mNEOs in soil. Especially, it is unknown that the effects of agricultural factors, such as plastic filming, plowing, irrigation, and fertilization, on mNEOs. This study is the first to reveal that mNEOs were commonly found in agricultural topsoil in China, with a geometric mean concentration of ΣmNEOs of 0.298 μg/kg. Among 31 provinces in Mainland China, Fujian had the highest mNEO residues, whereas Shanghai had the lowest. Among topsoil of various crop types, that of fruits and vegetables were found the highest mNEO residues. Furthermore, higher levels of film cover were associated with higher mNEO residues. Microplastics (MPs, serving as contaminant carriers) were positively correlated with mNEOs under field conditions, which was related to the adsorption capacity of microplastics and its influence on the soil conditions and the years of film cover. Alternatively, this study shows for the first time that irrigation water and manure might be sources of mNEO input into the soil, and that the plowing frequency might also influence on mNEOs., 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 © 2024 Elsevier B.V. All rights reserved.)

A comprehensive understanding of nitrogen pollution status, especially the identification of sources and fate of nitrate is essential for effective water quality management at the local scale. However, the nitrogen contamination of surface water across China was poorly understood at the national scale. A dataset related to nitrogen was established based on 111 pieces of literature from 2000 to 2020 in this study. The spatiotemporal variability, source tracing, health risk assessment, and drivers of China's surface water nitrogen pollution were analyzed by integrating multiple methods. These results revealed a significant spatiotemporal heterogeneity in the nitrogen concentration of surface water across China. Spatially, the Haihe River Basin and Yellow River Basin were the basins where surface water was seriously contaminated by nitrogen in China, while the surface water of Southwest Basin was less affected. Temporally, significant differences were observed in the nitrogen content of surface water in the Songhua and Liaohe River Basin, Pearl River Basin, Southeast Basin, and Yellow River Basin. There were 1%, 1%, 12%, and 46% probability exceeding the unacceptable risk level (HI＞1) for children in the Songhua and Liaohe River Basin, Pearl River Basin, Haihe River Basin, and Yellow River Basin, respectively. The primary sources of surface water nitrate in China were found to be domestic sewage and manure (37.7%), soil nitrogen (31.7%), and chemical fertilizer (26.9%), with a limited contribution from atmospheric precipitation (3.7%). Human activities determined the current spatiotemporal distribution of nitrogen contamination in China as well as the future development trend. This research could provide scientifically reasonable recommendations for the containment of surface water nitrogen contamination in China and even globally., 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 © 2024 Elsevier Inc. All rights reserved.)

Forest and grass ecological space is the key component of the ecosystem and plays a vital role in regulating the carbon, water, and energy cycle. The long-term exploitation of forest and grass ecological space and huge population pressure have gradually degraded the function of China's ecosystem. Therefore, forest and grass ecological space plays an important role in maintaining the stability of the ecosystem. The relationship between forest and grass ecospatial network structure and ecosystem service has been the focus of research. In this study, the forest and grass ecospatial network is constructed based on the minimum cumulative resistance (MCR) model. Then, the topological indicators (degree, weight clustering coefficient, node weight, unit weight, weight distribution difference, betweenness, PageRank) of the forest and grass ecospatial network were calculated by combining the complex network theory to analyze the relationship between these topological indicators and the three ecosystems (water retention, soil conservation, carbon storage). Based on the ecological significance of topological indicators, we identified ecologically fragile areas and proposed areas and directions for optimizing the ecospatial structure. Results show that the spatial distribution of the three ecosystem services in the southeast region of China is higher than that in the northwest region of China and shows a gradual decrease from the east to the west. The degree, node weight, unit weight, PageRank, and betweenness were highly significant and positively correlated with the three ecosystem services, among which PageRank had the highest correlation with water retention (p < 0.01, R2 = 0.835). Based on the spatial distribution characteristics of the different topological indicators, the quantitative relationship between the structural characteristics of the forest and grass ecospatial network and ecosystem services is clarified, revealing the intrinsic connection between ecological processes and ecosystem services. Through rational optimization of the forest and grass ecospatial network, ecosystem services can be effectively improved and ecosystem stability can be enhanced. [ABSTRACT FROM AUTHOR]

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[Display omitted] • A 250 m resolution black soil distribution map of China was developed. • Random forest classifier can accurately identify black soil at the national scale. • Daily mean land surface temperature and vegetation greatly affect black soil distribution. • A large area of unused black soil with reclamation potential in China. Black soil (BS) is an important soil resource. However, there is a lack of accurate information on BS spatial distribution, which affects the sustainable use and protection of BS. In this study, we linked BS distribution and machine learning. Random forest (RF) classifier and recent soil survey data were used to produce a high–precision BS distribution map in China. We analyzed environmental control factors of BS distribution. The results showed that the RF classifier method can well estimate the spatial distribution of BS at the national scale with an overall accuracy of 0.63 ∼ 0.91. The hot spots of BS distribution were mainly located in the Songnen Plain, Sanjiang Plain, the eastern side of the Greater Khingan Mountains and the western side of Changbai Mountains in Northeast China, the northeastern foot of Qilian Mountains in Qinghai–Tibet Plateau and the northern foot of Tianshan Mountains in Northwest China. Nearly 45 % BS area was covered by cropland. The daily mean land surface temperature and vegetation coverage had important controling effects on the BS distribution. Excluding the alpine mountains, BS area with potential for conversion to cropland can increase by 18.12 % (3.27 × 104 km2). The mapped BS distribution of China can serve as a benchmark for BS resource monitoring and play an important role in its assessment and protection. [ABSTRACT FROM AUTHOR]

As one group of emerging pollutants, the threat of organophosphate esters (flame retardants and plasticizers, OPEs) to drinking water safety is not well recognized. Now, the oral reference dose (RfD) and oral cancer slope factor (SFO) of OPEs have been updated by USPEA, therefore the threat of OPEs to drinking water safety could be assessed. In this study, occurrence, health risk and key impact factor of OPEs in drinking water of China were analyzed covering 79 cities, whose population and gross domestic product (GDP) accounted for 28.8% and 44.1% of them in China, respectively. Total concentration of 14 common OPEs in drinking water was 13.42–265.48 ng/L. The exposure level of OPEs via ingestion of drinking water was much lower than that of food ingestion but was comparable with dust ingestion, inhalation and dermal absorption. A health assessment for OPEs via ingestion of drinking water suggested that the potential cancer risk occurred (>1.00E-6) but no obvious non-carcinogenic effects occurred (<1). Tris-(2,3-dibromopropyl) phosphate (TDBPP) contributed to about 72.4% of carcinogenic risk, which should be treated as "prior monitoring OPEs" in further studies. The occurrence and distribution of OPEs in drinking water of China have a good corresponding relationship with the Aihui-Tengchong Line, and drinking water treatment technology (DWTT) was found to be a key factor. Total OPEs, halogeno-OPEs and alkyl-OPEs in drinking water from advanced DWTT cities were much lower than those of conventional DWTT cities. Compared with conventional DWTT, advanced DWTT could reduce about 65.6% and 36.5% of carcinogenic risk and non-carcinogenic risk of OPEs, respectively. Considering the annual growth of OPEs consumption in China and world, further studies regarding the environmental threat of OPEs are required. Image 1 • Comprehensive information about OPEs in drinking water was provided. • Exposure and health risk of OPEs via drink water were assessed. • OPEs in drinking water have potential cancer risk for consumer. • TDBPP should be treated as prior monitoring OPEs. • DWTT is a key factor on OPEs in drinking water of China. [ABSTRACT FROM AUTHOR]

Long-term human smelting activities have resulted in substantial heavy metals (HMs) pollution of farmland soils around smelting sites, and the safety of farmland products is critical for human health. The current study focuses on HMs in farmland soils surrounding a single smelter, therefore the impact of smelting on a national scale needs to be investigated further. This study was based on 116 papers and 1143 sets of relevant data for meta-analysis, and a hierarchical mixed-effects model was used to quantify the changes of HMs concentrations in farmland soils affected by non-ferrous metal smelting on a national scale, as well as their relationships with relevant explanatory variables in China. Results showed that: (i) non-ferrous metal smelting substantially increased farmland soils HMs concentrations (323%), with each HM concentration increasing in the following order: Cd (2753%) > Pb (562%) > Hg (455%) > Zn (228%) > Cu (158%) > As (107%) > Ni (52%); (ii) the highest increase of HMs in vegetable fields (361%), but not significant in comparison to other farmland categories, and the increase of Pb, Zn, Cu and As concentrations were significantly different in different types of smelting areas; (iii) the increase of Hg was significantly higher in the northern region than in the southern region, and the opposite increase of Cu; (iv) the soil depth from 0 to 40 cm was significantly affected by smelting, and the increase of multiple HMs were significantly positively correlated with soil pH and negatively correlated with distance; (v) the other explanatory variables (farmland category and soil organic matter) were not significantly related to the effect of smelting. The results can provide some reference for protecting and restoring farmland soils around smelting areas. [Display omitted] • Smelting-induced increase of HMs in farmland soils was quantified (323%). • Smelting resulted in the highest increase of farmland soil Cd and Pb (2753%, 562%). • Hg increases significantly higher in northern than southern and the opposite for Cu. • The increase of multiple HMs was significantly positively correlated with soil pH. • Using the new R package "orchaRd2.0″ to create meta-regression plots. [ABSTRACT FROM AUTHOR]

The contamination of soil by meso- and microplastics (MMPs) has been drawing increasing attention. However, the pollution characteristics of MMPs in mulching cultivated soil across China remain unclear. This study investigated the distribution of MMPs in long-term mulched soils in 29 provinces of China. MPs were found in all soil samples, while mesoplastics were found in only 29.6% of soil samples. The abundance of MPs in soil was 20.00–640.0 items·kg−1, and the average abundance was 213.0 items·kg−1. The average abundance of mesoplastics in the soil was 10.00 items·kg−1. MMPs were found to be primarily film-shaped (37.2%), blue in color (23.4%), and less than 1000 μm in size (39.7%), and the primary polymer was polyethylene (PE, 37.2%). Mulching times and crop types were important factors affecting MMP abundance in soil. These findings reveal the nationwide pollution pattern of MMPs in mulching cultivated soil over the long term, provide basic data for MMP pollution at the national scale, and provide a scientific basis for the rational use and management of plastic films and the treatment of soil MMP pollution. [Display omitted] • National-scale distribution of meso- and microplastic was demonstrated in soil. • Meso- and microplastic abundance varied in different regions. • Meso- and microplastic were found to be primarily film-shaped. • Mulching time, and crop types will affect the meso- and microplastic abundance. [ABSTRACT FROM AUTHOR]

Earthworms are important soil organisms that play critical roles in ecosystem material cycling and energy flows. Discovering and predicting the distribution of earthworm habitats is critical for managing biodiversity conservation projects and improving ecosystem health. However, earthworm data are challenging to obtain, and studies on the distribution of earthworms and factors affecting this have mainly been conducted in fields at a small scale; the spatial distribution of earthworms throughout China remains unclear. Species distribution models have been effectively used in macro-scale species suitability distribution studies; however, they have certain limitations. Thus, here, we optimized the maximum entropy model (MaxEnt) to achieve low complexity and high transferability, and the model was capable of predicting the potential distribution of earthworms in China. Modeling was based on the use of a developed database containing 286 earthworm occurrence records and 31 environmental variables (19 climatic, 9 soil, and 3 topographic variables). Results show that earthworm distribution is mainly controlled by the following environmental variables (with corresponding contribution rates): minimum temperature of the coldest month (18.47%), digital elevation model (17.65%), coarse fragments (16.72%), soil organic carbon (9.65%), soil type (7.53%), mean diurnal range (5.35%), and soil thickness (5.05%). The variables with the strongest influence on distribution are climate followed by landforms and soils. The relationship between the effect of environmental variables and earthworm distribution is not simple and linear, and each element has a certain threshold range. Only 50.67% of the total land area of China provides a suitable habitat for earthworms, and there are remarkable spatial differences. Of the various ecosystems, woodland ecosystems provide most of the suitable habitats, followed by cropland and grassland ecosystems, which together account for 45.74% of the land area. This study can be used as a reference for understanding and assessing ecosystem health, sustainability, and for enabling biodiversity conservation. • Earthworm-suitable habitats were predicted using optimized MaxEnt in China. • Factors influencing earthworm distribution were ranked and thresholds were analyzed. • Climate was more critical in changing earthworm habitats than topography and soil. • Area of suitable habitat for earthworms was 50.67% of the total land area. • Woodland and cropland ecosystems provide most of the suitable habitats for earthworms. [ABSTRACT FROM AUTHOR]

Identifying the potential soil pollution areas derived from the metal mining industry usually requires extensive field investigation and laboratory analysis. Moreover, the previous studies mainly focused on a single or a few mining areas, and thus couldn't provide effective spatial decision support for controlling soil pollution derived from the metal mining industry at the national scale. This study first conducted a literature investigation and web crawler for the relevant information on the metal mining areas in China. Next, MaxEnt with mine reserve scales (MaxEnt_MRS) was proposed for spatially predicting the probabilities of soil pollution derived from the metal mining industry in China. Then, MaxEnt_MRS was compared with the basic MaxEnt. Last, the potential soil pollution areas were identified based on the pollution probabilities, and the relationships between the soil pollution probabilities and the main environmental factors were quantitatively assessed. The results showed that: (i) MaxEnt_MRS (AUC = 0.822) obtained a better prediction effect than the basic MaxEnt (AUC = 0.807); (ii) the areas with the soil pollution probabilities higher than 54% were mainly scattered in the eastern, south-western, and south-central parts of China; (iii) GDP (45.7%), population density (30.1%), soil types (15.5%), average annual precipitation (3.9%), and land-use types (3.1%) contributed the most to the prediction of the soil pollution probabilities; and (iv) the soil pollution probabilities in the areas with all the following conditions were higher than 54%: GDP, 7600–2612670 thousand yuan/km2; population density, 152–551 people/km2; precipitation, 924–2869 mm/year; soil types, Ferralisols or Luvisols; and land-use types, townland, mines, and industrial areas. The above-mentioned results provided effective spatial decision support for controlling soil pollution derived from the metal mining industry at the national scale. [Display omitted] • 2088 metal mining areas and the relevant information were obtained in China. • MaxEnt_MRS was proposed by combining MaxEnt and mine reserve scales. • The soil pollution probabilities were spatially predicted by MaxEnt_MRS. • MaxEnt_MRS obtained a better prediction effect than the basic MaxEnt. • The relationships between pollution probabilities and the key factors were revealed. [ABSTRACT FROM AUTHOR]

The translocation and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) in the soil-crop system have important implications for the fate of PAHs and human health. This study summarized the concentrations of 16 priority PAHs in the soils and various parts of mature winter wheat in China, sourced from a screening of previous literature in English and Chinese databases. The study analyzes the distribution characteristics, transfer patterns, and human health risks of PAHs in sites studied in Shaanxi, Henan, and Shandong provinces. The results showed that the concentrations of Σ 16 PAHs in the rhizosphere soil of wheat ranged from 10.30 to 893.68 ng/g, in descending order of Shaanxi > Henan > average > Shandong. In sites with mild to moderate contamination (200 < Σ 16 PAHs < 600 ng/g; i.e., Henan and Shaanxi), the concentration of Σ 16 PAHs in the roots was higher than that in the stems or the grains, while in contamination-free sites (Σ 16 PAHs < 200 ng/g; i.e., Shandong), the highest concentration of Σ 16 PAHs was found in the stems. Generally, the concentrations of PAHs increased in the order of roots-stems-grains. The predominant PAHs in each part of wheat were 2- or 3-ring compounds, with five- or six-ring PAHs being more prevalent in wheat from Shanghe, Shandong. The bioaccumulation factors of different wheat parts from Shaanxi and Henan were consistently smaller than 1, and low- and medium-ring (2-4 rings) PAHs had bigger bioconcentration factors than high-ring (5-6 rings) PAHs. However, the accumulation of PAHs in the aboveground parts of wheat was larger than that in the underground parts of the Shandong sites. The linear regression relationship between the octanol-water partition coefficient and root concentration factor (RCF) of PAHs reflected that low and medium-ring PAHs were more easily absorbed by wheat roots than high-ring PAHs in Shaanxi and Henan. Our assessment of the health risks of oral wheat intake in adults and children by the incremental lifetime cancer risk (ILCR) model found a potential carcinogenic risk for both age groups in each province, with higher risks in adults than in children., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Bisphenol A (BPA), tetrabromobisphenol A (TBBPA), and their substitutes are commonly used in everyday products. However, large-scale internal exposure levels of them in China, the factors influencing on them, and the associated health risks were not systematically investigated still. In the present study, there were 1157 morning urine samples collected from residents of 26 provincial capitals in China for the measurement of BPA and seven bisphenol analogues, as well as TBBPA and its substitutes, i.e., tetrachlorobisphenol A and 4,4'-sulphonylbis(2,6-dibromophenol). The concentrations of Σ 8 bisphenols and Σ 3 TBBPAs ranged from

Nitrate sources in surface water have been identified using dual-isotope compositions of nitrate with various tools to efficiently manage the water quality at the local scale. Correlation between Cl and NO 3 has also been used to identify NO 3 . In this study, we assess the reliability of the dual-isotope approach and Cl in terms of nitrate source apportionment. To this end, we collected stream water samples throughout South Korea to estimate nitrate sources in streams and determine whether the land-use pattern was closely related to nitrate sources. The δ 15 N-NO 3 ranging from -1.3 to 14.8‰ showed a spatial distribution that was lower in mountain ranges (<7‰) than plain areas (>8‰). The Cl concentration in this national-scale distribution was also assessed. The relationship between the proportion of Cl and δ 15 N-NO 3 classifies nitrate sources into areas characterized by three land-use patterns: (1) agricultural and business areas, (2) forests in highlands, and (3) lowland forests, of which (1) had proportions of Cl >50%, while (2) and (3) were <50%. The samples in (3) showed δ 15 N-NO 3 values > 6‰, similar to those of (1). Deuterium excess of samples was negatively correlated (R 2  = 0.53) with δ 15 N-NO 3 , accounting for the fact that δ 15 N-NO 3 reflected land-use patterns. Samples were dominantly affected by agriculture-derived sources and domestic sewage showed NO 3 /Cl of <0.4 and δ 15 N-NO 3 of >6‰. These results suggest that nitrate source apportionment should be comprehensively evaluated considering the dual-isotope approach, land-use patterns, and Cl proportions., 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 © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

As a signatory of the Stockholm Convention and the largest developing country, China plays a very important role in implementation of the convention to reduce and finally eliminate persistent organic pollutants (POPs) in the world. In the past ten years after the enforcement in 2004, Chinese Government and scientists have made great progress on the study of POPs. The present work aims to provide an overview on recent studies on POPs in China, with particular focus on usage/emission inventory, residue inventory, and pollution status of POPs on national scale. Several legend (old) and new target POPs were comprehensively summarized with progress on inventory. Furthermore, several national scale monitoring programs have been selected for the occurrence, spatial and temporal trends of POPs in China, which are compared with Asian data and Global data. Based on the observed results, some important scientific issues, such as the primary and secondary distribution patterns, the primary and secondary fractionations, and air-soil exchange of POPs, are also discussed. It is proposed that more studies should be carried out for the new targeted POPs in future for both the national and global interests. [ABSTRACT FROM AUTHOR]

• We produced yearly maps of SOC to 1 m depth in China for 1982–2019 at a 1 km resolution. • The estimated SOC storage ranged from 89.03 to 97.41 Pg C and showed a slight increase over time. • Seventeen percent of all areas exhibited a substantial decrease in SOC since 1982. • We mapped the spatial distribution of the effects of environmental factors on SOC change. • Different factors drive SOC changes in different spatial domains. The evaluation of soil organic carbon (SOC) dynamics and its driving factors is important for developing sustainable soil C sequestration practices. A key challenge is the lack of a time series of spatially explicit SOC estimates; most previous SOC estimates are static. In this study, we applied a digital soil mapping framework to model the relationship between SOC and environmental factors based on a combined dataset of 4695 soil samples collected in China from the early 1980 s and during the 2000–2014 period. We predicted the annual SOC distribution at a depth of 0–100 cm at a 1 km resolution for China between 1982 and 2019. We mapped trends of SOC change and identified change hotspots. To obtain the pixel-level association between SOC change and environmental factors, we used a linear function to quantify the contribution of individual predictors to SOC change. The results show that the accuracy of SOC prediction is acceptable, with a mean R2 value of 0.58 for validation. SOC storage in China was estimated to range from 89.03 to 97.41 Pg C and showed a slight increase (slope = 0.024 Pg C/yr) from 1982 to 2019. Specifically, two distinct phases of SOC were identified as follows: (1) from 1982 to 2004, a considerable decline occurred, which was mainly driven by increased temperature; (2) from 2004 to 2019, SOC increased slowly, resulting from the contribution of greening to sustaining C sequestration in soils under warming conditions. Approximately 17 % of all areas have been characterized by a significant decrease in SOC since 1982, predominantly in central and western China. Environmental controls exhibited large spatial variation, where approximately 69 % of all areas were predominantly controlled by climate factors. For grasslands, the SOC losses in northern China were largely driven by temperature and precipitation, while the SOC losses were primarily attributed to decreased organic inputs driven by grassland degradation on the Tibetan Plateau. Policy-driven land use change has led to an increase in SOC in some cropland areas (e.g., northeast and east China). The implementation of ecological restoration has shown a positive influence on SOC sequestration. This study highlights the diverse spatial patterns and heterogeneity of SOC changes and their controls. Given this spatial differentiation, spatially explicit assessments of soil C dynamics are important for the formulation of regional soil-based mitigation strategies and guidance for effective restoration interventions based on geographic location. [ABSTRACT FROM AUTHOR]

Phthalates (PAEs) are widely used in daily products but can cause a variety of adverse effects in humans. Few studies have been carried out on human internal exposure levels of PAEs on a large-scale, especially in developing countries. In the present study, 1161 urine samples collected from residents of 26 provincial capitals in China were analyzed for nine phthalate metabolites (mPAEs). The chemicals were widely detected, and the median specific gravity adjusted urinary concentration of Σ 9 mPAEs was 278 μg/L. Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the main parent PAEs that the residents were exposed to. Demographic characteristics, such as age and educational level, were significantly associated with PAE exposure. Children and the elderly had higher mPAE levels. Subjects with lower educational levels were more frequently exposed to DnBP and DEHP. However, mono-ethyl phthalate showed the opposite trend, i.e., higher concentrations in subjects aged 18-59 years and with higher educational levels. Geographic differences were detected at the national scale. Residents in northeastern and western China had higher levels of mPAEs than those in central China, most likely because of different industrial usage of the chemicals and different living habits and living conditions of the residents. Health risk assessment showed that hazard indices of PAEs ranged from 0.07 to 9.34, with 20.0% of the subjects being concern for potential non-carcinogenic risk as assessed by Monte Carlo simulation. DEHP and DnBP were the primary contributors, representing 96.7% of total risk. This first large-scale study on PAE human internal exposure in China provides useful information on residents' health in a developing country, which could be used for chemical management and health protection., 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.)

Previous studies about heavy metal (HM) accumulation in the surrounding areas affected by mining mainly focused on a single or just a few mining areas. However, these studies could not provide adequate information supporting HM controls in soils at the national scale. This study first conducted a literature investigation and collected HM data in mining areas in China from 263 pieces of published literature. Then, geo-accumulation index (I geo ), ecological risk index (ER), and health risk assessment model were adopted to evaluate their HM pollution, ecological risks, and health risks, respectively. Finally, Geodetector and Pearson correlation coefficients were used to explore the relationships between the spatial distribution patterns of HMs in soils and their influencing factors. Results showed that: (i) the average concentrations of Cd, Hg, Pb, Zn, Cu, As, Ni, and Cr were 5.4, 1.2, 335.3, 496.1, 105.8, 55.0, 42.6, and 72.4 mg kg -1 , respectively, in the surrounding areas affected by mining in China; Cd pollution in soils (I geo = 2.9) was most severe; Cd (ER Cd > 320) and Hg (ER Hg > 320) were the main ecological risk factors; (ii) among the selected factors, mine types, clay content, soil organic carbon, and precipitation with the highest relative importance for the spatial distribution patterns of the HMs; (iii) HM accumulation were inversely proportional to soil pH, and were proportional to clay content, precipitation, and temperature; (iv) As, Cd, Hg, Pb, and Ni should be selected as the HMs to be controlled preferentially; (v) priority attention should be given to mining areas in Central South China, Southwest China, Liaoning province, and Zhejiang province; (vi) special attention should be given to mining areas of antimony, tin, tungsten, molybdenum, manganese, and lead‑zinc. The above results provided crucial information for HM control in the areas affected by mining at the national scale., 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.)

[Display omitted] • Large-scale PAH biomonitoring in the general population of China was conducted. • Regional differences of urinary OH-PAHs among the cities were analyzed. • Smoking is important factor led the association of OH-PAHs with other demographics. • Inhalation may be the main route of human exposure to PAHs, especially for smokers. • The Chinese general population exposed to PAHs had potential carcinogenic risk. Polycyclic aromatic hydrocarbons (PAHs) derived from the incomplete combustion of organic materials are associated with adverse health effects. However, little is known about PAH exposure levels and their influencing factors on a large scale in developing countries. In this study, urinary monohydroxylated metabolites of PAHs (OH-PAHs), including the metabolites of naphthalene, fluorene, phenanthrene, pyrene, chrysene, and benzo[a]pyrene, were measured in 1154 samples in the general population nationwide from 26 provincial capitals in China. Concentrations of OH-PAHs ranged from 1.39 to 228 μg/L. OH-Nap, metabolite of naphthalene, was the predominant compound, accounting for 65.1% of totals. People in eastern, southwest and northeast China, such as Shanghai, Kunming, Nanning, and Changchun, suffered more PAH exposure than other regions which might associate with sampling time, living habits of the subjects, and the imbalance of economic development and energy consumption across regions. Urinary OH-PAH concentrations were associated with body mass index, gender, and age, and smoking was the main correlating factor. Inhalation and diet might be the main exposure route of human exposure to PAHs, especially for smokers by inhalation. Hazard indices showed that no subject was exposed to PAHs with potential non-carcinogenic risk. Furthermore, the carcinogenic risk was the most significant health effects, with almost all subjects having carcinogenic risk values higher than the acceptable level of 10−6. Naphthalene and phenanthrene were the main contributors. The results also suggested a possible relationship between PAH exposure and lung cancer in the Chinese population. This first nationwide study on human internal exposure to PAHs provides a large body of scientific information for governmental decision-making about associated human health and the prevention of human exposure to PAHs. [ABSTRACT FROM AUTHOR]

Previous studies about the effects of mining on the potentially toxic elements (PTEs) in the surrounding soils mainly focused on single or few mining areas. However, these studies couldn't comprehensively quantify the mining-induced variations of soil PTE concentrations at the national scale. Moreover, the quantitative relationships between the effects of mining on soil PTEs and some related factors remained unclear at the national scale. This study first conducted a literature survey for soil PTE data affected by mining in China. Then, the random-effects model in the meta-analysis was used to quantify mining-induced variations of soil PTE concentrations in the surrounding areas. Last, the single meta-regression was used to explore the relationships between the effects of mining on soil PTEs and the related factors at the national scale. Results showed that: (i) mining-induced increases of soil PTE concentrations followed the order: Cd (1017%) > Hg (319%) > Pb (291%) > Zn (176%) > Cu (129%) > As (92%) > Ni (23%); (ii) mining-induced increases of soil PTE concentrations in clay (531%), non-ferrous mine (188%), paddy field (212%), and Central South China (290%) were more than those in other soil textures, mine types, land-use types, and geographical divisions, respectively; (iii) the effects of mining on soil PTEs were negatively correlated with soil pH (Q M = 29.76, p < 0.01) and positively correlated with soil organic carbon (Q M = 28.54, p < 0.01) and mean annual precipitation (Q M = 91.75, p < 0.01); (iv) the effects of mining overall decreased with the sampling year (Q M = 35.01, p < 0.01) and showed latitudinal zonality (Q M = 180.39, p < 0.01). The above results provided valuable information for soil PTE mitigation in the areas affected by mining in China., 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.)

In China, ground-level ozone has shown an increasing trend and has become a serious ambient pollutant. An accurate spatiotemporal distribution of ground-level ozone concentrations (GOCs) is urgently needed. Generalized linear models (GLMs) and Bayesian maximum entropy (BME) models are practical for predicting GOCs. However, GLMs have limited capacity to capture temporal variations and can miss some short-term and regional patterns, while the performance of BME models may degrade in cases of sparse or imperfect monitoring networks. Thus, to predict nationwide 1 km monthly average GOCs for China, we designed a novel hybrid model containing three modules. (1) A GLM was established to accurately describe the variability in GOCs in the space domain. (2) A BME model incorporating GLM residuals was employed to capture the temporal variability of GOCs in detail. (3) A combination of GLM and BME models was developed based on the specific broad range of each submodel. According to the cross-validation results, the hybrid model exhibited superior performance, with coefficient of determination (R2) values of 0.67. The predictive performance of the large-scale and high-resolution hybrid model is superior to that in previous studies. The nationwide spatiotemporal variability of the GOCs derived from the hybrid model shows that they are valuable indicators for ground-level ozone pollution control and prevention in China. [ABSTRACT FROM AUTHOR]

Countries and regions with vast territory tend to have economic gradients and uneven land use pattern. Ecological sensitive zones, transitional zones and state poverty counties have been found near the Hu Huanyong Line (Hu Line) of China in previous studies. However, there is little knowledge about the identification of a comprehensive transitional zone that considers natural and socio-economic elements from national scale. Based on exploring gradient characteristics of land use patterns and the driving factors behind them, we propose a quantitative identification framework of natural-socio-economic transitional zone via multi-source data and methods of gradient analysis and change-point analysis. Taking China as an example, this study showed evidence of the discontinuity in each factor between the east and the west, and identified an east-west natural-socio-economic transitional zone (EWNSETZ) along the Hu Line. The EWNSETZ, determined by combining the integrated abrupt change zone of natural and socio-economic factors with the farming-pastoral ecotone (FPE), accounted for about 1/5 of China's total land area and had more balanced distribution of land use types but more fragile environment and inferior combination of resources. Measures such as completing ecological compensation mechanism, developing tourism and green industries, increasing the supply of water resources and speeding up the construction of infrastructure and facilities can be used to promote the ecological-economic coordinated development of the EWNSETZ and eventually to drive the development of the western region. In particular, comprehensively consider the natural geographical conditions, key ecological function areas distribution and ecosystem services supply and demand of the EWNSETZ, the strategic orientation in its different parts should be focusing on different key points. • Exploring gradient characteristics of land use patterns and their driving factors. • The gradient analysis and multi-source data were employed. • There were discontinuities in land use patterns and their driving factors between the east and the west of China. • The east-west natural-socio-economic transitional zone (EWNSETZ) had more balanced distribution of land use types. • The strategic orientation in different parts of the EWNSETZ should be focusing on different points. [ABSTRACT FROM AUTHOR]

This study represents an initial attempt to examine environmental justice on inequalities in access to ecological attractions that provide top cultural ecosystem services at a national scale. With big data from social media, billions of anonymized samples were analysed via an experimental procedure to capture the behavioral characteristics of visitors who accessed China's Five-A ecological attractions. The results indicate that (1) social equity can be achieved in the context of ecosystem services in China, especially at the individual level; and (2) although China's vulnerable groups do not appear to have been treated unfairly, market mechanisms may exacerbate the inequitable development of ecosystem services among different regions. To address the problem of inequality and uneven development on ecosystem services that may result from the capital, the government should take measures to reduce the accessibility threshold and consider providing appropriate green infrastructure for different social groups apart from Five-A ecological attractions. Image 1 • A big data method to re-visit access of top ecological spaces at a national scale. • Vulnerable groups were not unequally treated on environment recreation in China. • The equality of accessibility frequency appears much greater than distance. • People-based measures of accessibility are more reliable than place-based measures. • Age, income, and hukou rate were unrelated to accessibility at a national scale. [ABSTRACT FROM AUTHOR]

In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ 209 PCBs in soils across China was in the range of 64.3–4358 pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44 + 47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44 + 47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China. Image 1 • A complete analysis of 209 PCBs were conducted in agricultural soils across China. • PCB11, PCB44 + 47+65, PCB68, and PCB209 were dominant congeners among all 209 PCBs. • The spatial distributions of non-Aroclor congeners were dependent on local sources. • The 7 indicator PCBs were dominated (52%) by the legacy commercial products. • Unintentional sources were the dominant contributor (57%) of the total PCBs in soils. The main finding of this work : PCBs in Chinese agricultural soils were dominated by non-Aroclor congeners. Unintentional sources contributed 57% of the total PCBs in soils. [ABSTRACT FROM AUTHOR]

Soil is a reservoir of environmental resistomes. Information about their distribution, profiles, and driving forces in undisturbed environments is essential for understanding and managing modern antibiotic resistance genes (ARGs) in human disturbed environments. However, knowledge about the resistomes in pristine soils is limited, particularly at national scale. Here, we conducted a national-scale investigation of soil resistomes in pristine forests across China. Although the antibiotics content was low and ranged from below limit of detection (LOD) to 0.290 μg/kg, numerous detected ARGs conferring resistance to major classes of modern antibiotics were identified and indicated forest soils as a potential source of resistance traits. ARGs ranged from 6.20 × 10−7 to 2.52 × 10−3 copies/16S-rRNA and were predominated by those resisting aminoglycoside and encoding deactivation mechanisms. Low abundance of mobile genetic elements (MGEs) and its scarcely positive connections with ARGs suggest the low potential of horizontal gene transfer. The geographic patterns of ARGs and ARG-hosts in pristine forest soils were mainly driven by soil physiochemical variables and followed a distance–decay relationship. This work focusing on pristine soils can provide valuably new information for our understanding of the ARGs in human disturbed environments. ga1 • National scale investigation on ARGs in pristine forest soils. • Occurrence of 30 ARGs resisting modern antibiotics in pristine forest soils. • Geographic patterns of ARGs and ARG-hosts followed a distance-decay relationship. • Soil physicochemical variables are key driving forces for ARGs distribution. [ABSTRACT FROM AUTHOR]

Managing excess nitrogen (N) fertilizers remains a major obstacle to improving crop growth and environmental sustainability. To provide information for more quantitative N management, N use efficiency (NUE f) and N emissions ratio of fertilizer (NER f) in China were estimated at high resolution from 2004 to 2017. A descriptive variable (H/E value) was utilized to determine the fate of N fertilizers between crop production and the consequent N emissions. Furthermore, the related environmental impacts, in terms of water pollution relating to surface runoff and leaching, global warming and acidification effect, were analyzed in this study. The results indicated although NUE f had increased from 21.61% to 26.47%, it was still much lower than that of developed countries due to regional imbalance in China. Accordingly, the emissions of N fertilizers were estimated as 18.52%–24.75% at high resolution across China. Those higher H/E values were observed in the northeastern and eastern China, indicating that these two regions had effective agricultural production. However, the water pollution caused by N fertilizers was in the northern part of China due to the shortage of water resources, while Yangtze River delta, Lianghu Plain, Yungui Plateau and Pearl River Delta had been identified as the hotspots of global warming and acidification effect due to abundant water system and rice cultivation. Consequently, it was suggested that different N management strategies should be developed by considering particular environmental impacts and simultaneously achieving sustainable agricultural development. Image 1 • The comprehensive fate of N fertilizer was evaluated at the national scale. • Multiple loss pathways of N fertilizer were compared at high resolution. • Spatial-temporal variability of the fate of N fertilizer was identified. • Hotspots for environmental impact of multi-pathways loss were identified. • It was found that 18.52%–24.75% of N fertilizer was loss to the environment. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in atmosphere, which attracted more attentions due to their influence on human health. In this study, a national scale cancer risk (CR) assessment with atmospheric PAHs were conducted based on one year monitoring program at 11 cities across China. The annual mean concentrations of benzo[a]pyrene (BaP) and BaP equivalency (BaP eq) were 4.56 ± 7.78 ng/m3 and 8.45 ± 14.1 ng/m3, respectively, which were both higher than the new ambient air quality standards of China (GB 3095–2012, 1 ng/m3). Concentrations of BaP and BaP eq in northern Chinese cities were almost 2 times higher than those in southern Chinese cities. The CR values induced by the dermal contact exposure were two orders of magnitude higher than that by the inhalation exposure. Children and adults were the most sensitive age groups with the dermal contact exposure and the inhalation exposure to atmospheric PAHs, respectively. For the total CR values, 99.7% of its values were higher than the reference level of 10−6. No significant difference of the total CR values was observed between northern Chinese and southern Chinese cities for children and adults. In order to quantify the uncertainties of CR assessment, Monte Carlo Simulation was applied based on the specific distributions of the exposure factors cited from the Exposure Factors Handbook of Chinese Population. The results indicated that almost 90% probability of the total CR values were higher than 10−6, indicating potential cancer risk. Sensitive analysis indicated that atmospheric concentration, outdoor exposure fraction, particle amount adhered to skin, and cancer slope factor should be carefully considered in order to increase the accuracy of CR assessment with PAHs in atmosphere. Image 1 • National scale cancer risk assessment with atmospheric PAHs was conducted in China. • Annual mean BaP and BaP equivalency were higher than standards of China (GB 3095–2012). • Dermal contact exposure has higher cancer risk than inhalation exposure. • Chinese exposure factors were applied to quantify uncertainties of cancer risk. [ABSTRACT FROM AUTHOR]

China is one of the largest coastal countries in the world, which have all kinds of marginal systems. Studies have reported the sedimentary Polycyclic aromatic hydrocarbons (PAHs) pollution status, including their concentrations, sources and risks, in localized marginal systems, which showed significant differences. Thus, a comprehensive understanding of their pollution in marginal systems along China Mainland is urgently needed on a national scale. In the present study, the concentrations of 16 priority PAHs in surface sediments from 62 different marginal systems along China Mainland were reviewed. Their sources were identified and apportioned, and the health risks and ecological risks were also evaluated. As a result, the total sedimentary PAHs varied in a wide range of 4–3700 ng/g, with the lowest values observed in Kenting National Park in East China Sea and the highest values observed in Daliao River estuary in Bohai Sea. Their concentrations suggested that they were not contaminated-weakly contaminated in most study areas, but were contaminated-heavily contaminated in some pollution hot-spots. Source identification and apportion suggested that the sedimentary PAHs were mainly originated from coal combustion, vehicular emission, natural gas combustion and petrogenic source, but the coal combustion and vehicular emission contributed most to their emission (>90%). Risk assessment suggested that the carcinogenic risks were lower than the upper limit of the acceptable range (10−4), which were acceptable at a large spatial scale. However, for sediments from Qinhuangdao coastal wetland, Daliao River estuary and Yangpu Bay, their carcinogenic risks were higher than 10−4, which will pose high carcinogenic risks for adults. The non-carcinogenic risks were acceptable in all marginal systems with values lower than the safety guideline (<1). In the ecological risk assessment, their concentrations in some pollution hot-spots were higher than the safety guidelines (effects range low, ERL), suggesting a higher potential ecological risk. Image 1 • National-scale contaminations of 16 PAHs in different marginal systems were reviewed. • PAHs in Bohai Sea and Yellow Sea were higher than East and South China Sea. • Coal combustion and vehicular emission were the main sources with contributions >90%. • Carcinogenic and ecological risks in pollution hot-spots were higher than guidelines. This paper reported the pollution status of the sedimentary PAHs in marginal systems along China Mainland and quantified their sources and risks. [ABSTRACT FROM AUTHOR]

• Interactive effects of natural-human factors on vegetation coverage were quantified. • The area with a probability of degeneration ≥80% covered 16.6% of study area. • Models with vegetation coverage (2000) largely accounted for the vegetation variance. • The major drivers of vegetation coverage changed with time and variables. Vegetation coverage in coastal wetlands has been significantly altered in response to multiple disturbances over recent decades. However, the major driving factor of vegetation coverage in coastal wetlands remains unclear, with natural and human factors playing interactive roles at the national scale. To identify the major controls of vegetation coverage in coastal wetlands, structural equation modeling (SEM) was conducted to quantify the relative contribution of natural and human factors to vegetation coverage in coastal wetlands in China over a 16-year period (2000–2015). The results showed that, in brief, vegetation coverage was slightly degraded (k = −0.0035) over the 2000–2015 period. The area with a probability of vegetation coverage degeneration ≥80% covered 16.6% of the study area. Most annual mean vegetation coverage was lower but improved near the sea, with inverse results obtained near land. In 2000, human1 (population and GDP, r = −0.31) and topography (r = 0.32) were the major controls of vegetation coverage. The vegetation coverage (2000) played the most important and positive role (r = 0.62, r = 0.66) in the vegetation coverage in 2015. Our findings highlight that the major drivers of vegetation coverage in coastal wetlands changed with time and selected variables. [ABSTRACT FROM AUTHOR]

Mining is a common industrial activity and significant source of soil heavy metal (HM) pollution. However, nearly all studies on the effects of mining activities on soil environmental quality have entailed field monitoring of small regions or bibliometric analyses. This study therefore investigated the pollution of surface soils surrounding 135 large opencast coal mining pits in China. A total of 1772 surface soil samples were collected, and the concentrations of eight major HMs were determined. The HM concentrations in this study were relatively lower than the published HM concentrations of coal mine soils from 50 typical Chinese coal mines. However, pollution assessments indicated that Cd, Cu, and As concentrations were concerning. Significant correlations existed between all of the HMs and mining pit area (p < 0.01), as well as between the Pb and Zn concentrations and direction (p < 0.05). Climate conditions had large influences on the HM concentrations. The concentrations of all studied HMs, except for Ni, were highest in Anthrosols and lowest in hydromorphic soils. The concentrations of all HMs, except for Hg, in land use types showed a descending trend of cultivated land > garden plot > grassland. Significantly negative correlations (p < 0.01) between all HM concentrations and elevation were observed. Cr, Zn, and Ni were significantly and positively correlated with the slope, and no HMs, except Cr, showed significant correlations with the parcel area. This paper provides insights for the policymakers regarding soil pollution control and management strategies near coal mine pits. • Heavy metal contamination was studied at opencast coal mining pits in China. • Among the metals studied, Cd exceeded the risk screening level the most frequently. • Climate and soil type influenced the heavy metal concentrations. • The results should be valuable for the development of soil remediation strategies. [ABSTRACT FROM AUTHOR]