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Ecosystems on earth have endured rapid changes over the last decades, but freshwater wetlands have disproportionally suffered biodiversity loss. Understanding the drivers of the decline of wetland ecosystems is the prerequisites for effective management scheme. However, a lack of long-term data on biological indicators like benthic macroinvertebrates have limited our understanding. Under the critical time window of the recent Anthropocene, China's longest in-situ aquatic biomonitoring data were combined with satellite imaging to construct profiles of some essential biodiversity variables of the Dongting Lake, a large Ramsar wetland in the Yangtze River basin. The results showed that the integrity of macroinvertebrate community systematically declined in the last three decades, accompanied by the stresses of lake eutrophication, climate warming and weakening of the connectivity between the Yangtze River and the lake. Unlike previously speculated attribution, the establishment of the Three Gorges Dam was found to only have a limited impact on the biodiversity loss of Dongting Lake. Changes in human land-use intensity in the surrounding terrestrial ecosystem, by increasing nutrient loading, were found to be the main mechanism resulting in the decline of macroinvertebrates. Biodiversity changes were most influenced by land-use within 1.5 km from the water body. The results highlight that to attenuate such a major local land-use effect, establishing a protected buffer area surrounding wetland ecosystems will help preserve biodiversity in the future.

Decomposition of dichloromethane (DCM) in water was carried out by electrolysis in combination with persulfate oxidation, and a significant synergistic effect was found in the anode chamber of a du...

In recent years, carbon tetrachloride (CT) has been frequently detected in surface water and groundwater around the world; it is necessary to find an effective way to treat wastewater contaminated with it. In this study, Ni/Fe bimetallic nanoparticles were immobilized on reduced graphene oxide (NF@rGO), and used to dechlorinate CT in aqueous solution. Scanning electron microscopy (SEM) demonstrated that the two-dimensional structure of rGO could disperse nanoparticles commendably. The results of batch experiments showed that the 4N4F@rGO (Fe/GO = 4 wt./wt., and Ni/Fe = 4 wt.%) could reach a higher reduction capacity (143.2 mgCT/gcatalyst) compared with Ni/Fe bimetallic nanoparticles (91.7 mgCT/gcatalyst) and Fe0 nanoparticles (49.8 mgCT/gcatalyst) respectively. That benefited from the nickel metal as a co-catalyst, which could reduce the reaction activation energy of 6.59 kJ/mol, and rGO as an electrical conductivity supporting material could further reduce the reaction activation energy of 4.73 kJ/mol as presented in the conceptual model. More complete dechlorination products were generated with the use of 4N4F@rGO. Based on the above results, the reductive pathway of CT and the catalytic reaction mechanism have been discussed.

Dissolved organic matter (DOM) plays a central role in the global carbon cycle. The Huma River Basin (HRB) in China is affected by humic substances in its forests with high background values. DOM in the HRB was studied using spectroscopic techniques combined with statistical analysis in order to better understand its characteristics in natural waters affected by humic substances in forests. UV-visible parameters showed that the DOM predominantly consisted of aromatic and high-molecular-weight natural organic matter. Fluorescence excitation-emission matrix (EEM) spectroscopy-parallel factor analysis (PARAFAC) recognized four characteristic components, representing humic-like substances (C1, C2, and C3) and protein-like substances (C4). Fluorescence parameters showed that the allochthonous terrestrially-derived DOM had a humic character. Fourier transform infrared (FT-IR) spectra characterized the structure of DOM, containing aromatic, aliphatic, carbohydrate, and protein compounds. Principal component analysis (PCA) revealed that humic-like components explained approximately 86.7% of the total variance, suggesting that terrestrial humic-like substances were dominant in the HRB. Correlation coefficient matrix analysis indicated that CODMn and DOC were mainly derived from humic-like substances. The results demonstrated that the background value in the HRB was mainly attributed to terrestrial humic-like substances. Such knowledge could assist in monitoring and managing rivers with high background values.

Nitrogen pollution is a severe problem in the Songhua River Basin (SHR) in China. Samples were collected from 36 sections of the SHR during the high, low, and flat seasons of the river, and the main sources of nitrogen in the water were qualitatively analyzed with isotope data for nitrogen and oxygen of nitrate. The contribution rates of each major pollution source were quantitatively analyzed using the Iso Source mass balance model. The results from these experiments indicate that the values for δ15N-NO3 and δ18O-NO3 in the flat flow season range from 1.52‰ to 14.55‰ and −14.26‰ to 2.03‰, respectively. The values for δ15N-NO3 and δ18O-NO3 in the low flow season range from 6.66‰ to 15.46‰ and −5.82‰ to 65.70‰, respectively. In the low flow season, nitrogen comes from the input of domestic and manure sewage (53%) and soil organic N (45%). The values of δ15N-NO3 and δ18O-NO3 in the high flow season range from 2.07‰ to 14.24‰ and −3.99‰ to 8.03‰, respectively. In the high flow season, nitrogen comes from soil organic nitrogen (41%), domestic and manure sewage (32%), and nitrogen fertilizer (27%), which are the main sources of nitrogen pollution in the SHR. The conclusions from the qualitative and quantitative analysis of nitrogen sources in the SHR can provide a scientific basis for the source control and treatment of nitrogen pollution.

The cathode chamber of a dual-chamber electrochemical reactor separated by DuPont proton exchange membrane, which has a higher reductive capacity than a single-chamber reactor, has a remark...

To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) and its chemical compositions in the Beijing-Tianjin-Hebei (BTH) region of China during the novel coronavirus disease (COVID-19) lockdown, the ground-based data of PM2.5, trace gases, water-soluble inorganic ions, and organic and elemental carbon were analyzed in three typical cities (Beijing, Tianjin, and Baoding) in the BTH region of China from 5-15 February 2020. The PM2.5 source apportionment was established by combining the weather research and forecasting model and comprehensive air quality model with extensions (WRF-CAMx). The results showed that the maximum daily PM2.5 concentration reached the heavy pollution level (>150 μg/m3) in the above three cities. The sum concentration of SO42−, NO3− and NH4+ played a dominant position in PM2.5 chemical compositions of Beijing, Tianjin, and Baoding; secondary transformation of gaseous pollutants contributed significantly to PM2.5 generation, and the secondary transformation was enhanced as the increased PM2.5 concentrations. The results of WRF-CAMx showed obviously inter-transport of PM2.5 in the BTH region; the contribution of transportation source decreased significantly than previous reports in Beijing, Tianjin, and Baoding during the COVID-19 lockdown; but the contribution of industrial and residential emission sources increased significantly with the increase of PM2.5 concentration, and industry emission sources contributed the most to PM2.5 concentrations. Therefore, control policies should be devoted to reducing industrial emissions and regional joint control strategies to mitigate haze pollution., Graphical abstract Image, graphical abstract

To investigate the monitoring history and long-term change trends in surface water quality in China since the reform and opening up, the history of surface water environment monitoring is summarized, including monitoring scope, monitoring methods, and technical requirements. Temporal and spatial patterns of surface water quality in China were analyzed based on the monitoring results. In the past 40 years, the monitoring targets for surface water quality have been continuously improved, the frequency of monitoring has become more science-based, and the monitoring indicators are now comprehensive. Overall, the temporal change trend in surface water quality has followed a “fluctuating changes stage—rapid deterioration stage—fluctuations stalemate stage—rapid improvement stage” pattern. However, the current regional surface water quality is still in a polluted status, and there is a gap between surface water quality status and the goal of building a well-off society. At present, China’s surface water pollution is prone to high numbers of incidents and the treatment of surface water pollution has entered a crucial stage. The potential for the continuous reduction of major pollutant discharges has become more challenging, and the marginal cost for pollution control has increased. It is very difficult to comprehensively solve the outstanding water environment problems. In addition to strengthening the existing work on surface water quality control, it is also necessary to strengthen the work of risk identification, early warning, and regulation implementation of the surface water environment. During the 14th year plan period (2021–2025), the overall planning on water resources, water ecology, and water quality will be implemented, and beautiful rivers and lakes will be created.

Detection and quantification of heavy metals in soil samples are significant in terms of environmental monitoring and risk assessment for metals. In order to improve the accuracy and precision to detect heavy metal, in this study, four standard samples (NASS-4, NASS-5, NASS-9, and NASS-16) were analyzed by evolving heating (electric heating plate, water bath, and microwave) and acidic systems (includes HCl, HNO3, HF, and HClO4). The result shows that different pretreatment methods have different effects on the extraction of heavy metal elements and five heavy metal elements (Cu, Zn, Pb, Ni, and Cr) were selected for optimization through pretreatment methods. Although the contents of heavy metals were same but we found diversity in the results. Under optimal conditions, the selected standard samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and atomic absorption spectroscopy (AAS), and the results were compared. The results show that different elements have their own most suitable detection methods, such as for Pb, the most suitable method is ICP-MS; and for Zn, the most suitable method is AAS. Pretreatment methods and detection techniques are combined to find and improve accuracy of results for certain elements. This study provides a reliable detection method for the accurate detection of heavy metals in the environment.

Detection and quantification of heavy metals in soil samples are significant in terms of environmental monitoring and risk assessment for metals. In order to improve the accuracy and precision to detect heavy metal, in this study, four standard samples (NASS-4, NASS-5, NASS-9, and NASS-16) were analyzed by evolving heating (electric heating plate, water bath, and microwave) and acidic systems (includes HCl, HNO

Herein, we reported the synthesis of nanoscale zero-valent iron particles stabilized by sulfur/nitrogen dual-doped r-GO (nZVIPs@SN-G) and their applications as the heterogeneous catalysts to the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) by combining H2O2 under varying pHs, temperatures, catalyst dosages and H2O2 concentrations, as well as in the presence of radical scavengers. The experimental results showed that this heterogeneous Fenton-like catalytic system remained effective up to 90 min of reaction time, and could reach at least 98% degradation efficiency at the optimal conditions, especially when the initial pH values were below 4.5. And the scavenging experiments revealed that 2,4-D was mainly decomposed by the attack of surface-bounded hydroxyl radicals ( OH). The structure and properties of the nZVIPs@SN-G catalyst was characterized by X-ray diffraction (XRD), scanning elctron microscopy (SEM), surface area analysis (BET), Raman spectroscopy (Raman) and X-ray photoelectron spectroscopy (XPS). The SEM images indicated that nanoscale zero-valent iron particles (nZVIPs) with size of about 10–50 nm were uniformly stabilized on the surface of sulfur/nitrogen dual-doped r-GO (SN-G), and had good combination with the multilayer matrix. Additionally, the catalyst at the optimum pH could maintain effective degradation even after five cycles, and achieved 91% degradation efficiency of 2,4-D, which was indicative of a good stability. More importantly, the possible reaction mechanism and dechlorination pathway of 2,4-D by the nZVIPs@SN-G/H2O2 heterogeneous catalytic system was also illustrated in this study.

Triadimefon, a broad-spectrum, systemic fungicide used to protect agricultural crops is popular in China. However, sub-lethal effects of triadimefon on aquatic organisms remained poorly understood, and its risks to aquatic organisms were unclear. In the current study, thresholds for chronic toxicity to five aquatic organisms were determined and a PNEC based on reproductive fitness of nine aquatic organisms was derived through use of a species sensitivity distribution (SSD). NOECs, based on reproduction or inhabitation of growth, for Oryzias latipes, Daphnia magna, Brachionus calyciflorus, Heterocypris incongruens and Soirodela polyrhiza were 5, 25, 80, 320 and 500 μg L−1, respectively, and the final PNEC derived was 3.66 μg L−1. A screening-level hazard assessment of surface water based on both measured environment concentrations (ND∼5.22 μg L−1) in 3 lakes, 2 reservoirs and 1 river and predicted environment concentrations (0.36–65 μg L−1) in a simulated river and pond, identified unacceptable hazard to aquatic organisms posed by triadimefon, with maximum hazard quotients (HQs) of 1.43 and 17.8, respectively. Potential deleterious effects and hazards or risks of exposure of aquatic organisms from current patterns of use of triadimefon in surface water if of concern. Since HQs were relatively small and the benefits large, it is suggested that mitigations be applied to allow use while minimizing potential for adverse effects on aquatic organisms.

Herein, Pd/Fe bimetallic nanoparticles (Pd/FePs) were uniformly distributed on the surface of graphene sheet structure, and had good combination with the multilayer substrate. The nanocomposites could maintain high reactivity even after five times degradation reactions of carbon tetrachloride (CT) in succession, indicating that the modified technology had a positive effect on achieving high surface activity and prolonging the longevity. The structure evolution and compositional changes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photo-electron spectroscopy (XPS). Also, humic acid (HA) as non-reactive adsorbate could preferentially occupy surface active sites of Pd/FePs to mediate the predominant radical species in the degradation process, which caused a 53% decrease in dechlorination rate of CT. These findings provided an important understanding of the stability and reactive mechanism involved in Pd/Fe bimetallic system toward CT degradation. Moreover, batch experiments were conducted to investigate the actual catalytic activity in view of the effects of common inorganic anions in aqueous solution. The results revealed that the presence of Cl−, HCO3−, and HPO42− was beneficial to the CT degradation while SO42- and NO3− exerted the negative effects. Based on the detection results by means of gas chromatography (GC) and ion chromatography (IC), a possible degradation pathway was propose.

Herein, we reported a study on using the catalytic performance of nanoscale palladized zero-valent iron@ graphene composites (PFGC) synthesized by using coprecipitation method to significantly enhance carbon tetrachloride (CT) dechlorination in the laboratory, and then the nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunner-Emmet-Teler (BET), and X-ray photoelectron spectroscopy (XPS). The catalytic activity was investigated in consideration of several operation parameters including the initial pH, temperature, the dosage of nanocatalyst and the optimal content of palladium metal. The results showed that 50.4% and 93.5% CT (C initial = 3 mg L −1 ) were removed from aqueous solution by nZVI (Nanoscale zero-valent iron, 0.5 g L −1 ) and PFGC (Nanoscale palladized zero-valent iron@ graphene composites, using Fe/GO = 2:1 and Pd/Fe = 0.75%, 0.5 g L −1 ), respectively. The degradation kinetics of CT in all experiments followed pseudo first-order reaction kinetics. Moreover, it has been found that palladium metal (Pd 0 ) accelerated hydrogen formation and activation to generate atomic hydrogen (·H) which in turn behaved as the reducing agents responsible for the dechlorination reactions as presented in the conceptual model. And the activation energies reduced from 44.42 to 30.18 kJ/mol. However, it was very easy to agglomerate and form large-sized particles due to the high specific surface energy, hence, graphene as the supporting matrix graphically depicted in the SEM images increased specific surface areas to improve the dispersibility of bimetallic nanoparticles. After five successive runs, there was no significant reduction in the removal efficiency indicating a good reusability and stability of PFGC.

The community structure of benthic diatoms and water environmental characteristics were extensively investigated to assess the aquatic ecosystem health of the Wutong River (Heilongjiang Province, China). Several diatom indices were calculated, and a benthic diatom index based on biotic integrity (BD-IBI) was developed. Principal component analysis (PCA), Spearman correlation analysis (CA), cluster analysis, redundancy analysis (RDA), and the box plot analysis were used to analyze the benthic diatom communities, assess the river ecosystem health, and compare the applicability of different indexes. The results indicated that Gomphonema parvulum and other tolerant species were the dominant species. Meanwhile, most sites were in &ldquo, poor&rdquo, or &ldquo, very poor&rdquo, condition according to the diatom indexes evaluation, indicating that the river has been disturbed by human activities. The sampling sites of the Wutong River were divided into three groups based on different pollution levels. The derived BD-IBI included four individual metrics of different aspects, showed strong distinguishability for three grouping and robust correlation with environmental variables. Of all the indexes selected, IBI performed the best, followed by the species-level diatom indexes and the genus-level diatom indexes.

In this study, soil and rice samples from 85 sites in six cities in Hunan Province were analyzed for Cu, Zn, Pb, Cd, Hg, Mn, and Co (total and bioavailable concentrations for soil) in July 2014. The results indicated that the total concentrations of Cu, Zn, Pb, Cd, and Hg in soil had increased significantly compared with the 1980s, and were correlated with their bioavailable concentrations in soil positively. The total concentrations of Cd and Co in soil were correlated with those in rice. Bioavailable concentrations of Cd, Mn, Co, Pb, and Cu represented 64.4%, 33.2%, 12.0%, 11.6%, and 6.1% of the total soil concentrations, respectively. The bioavailable concentrations of Cd and Co in soil had a extremely significant (p &lt, 0.01) positive correlation with those in rice, suggesting that bioavailable concentrations was a better indicator for soil potentially toxic elements contamination. The pH values had a significant influence on the bioavailability of Cd and Cu and the amounts taken up by rice. The Cd contamination in 27.0% rice samples exceeded World Health Organization recommended thresholds. The results added basic pollution distribution data, further revealing the relationships of metals in soil and crops and would offer great help to the metallic pollution control in these areas.

Here, a new integrated methodology framework has been proposed for source apportionment and source-oriented risk evaluation, and applied to identify the characteristics, sources and health risks of PAHs in the soils of a typical cold region in Northeastern China. To this end, a large-scale data set containing 1780 soil samples and 16 priority PAHs has been collected from the study area. Two advanced receptor models, positive matrix factorization (PMF) and multivariate curve resolution-weighted alternating least-squares (MCR-WALS), have been comparatively employed to apportion the pollution sources of soil PAHs, with the help of a set of modified literature PAH source fingerprints. Further, the apportionment results have been incorporated into a probabilistic incremental lifetime cancer risk model for assessing the source-specific health risk of soil PAHs. Notably, the PMF and MCR-WALS models have apportioned essentially same results. The coal combustion and gasoline engine are identified as the main contributors of soil PAHs, with contributions of 57.9–58.1% and 25.2–22.2%, respectively. The health risks posed by PAHs in the soils are negligible for both adult and children; relatively, source-oriented risk assessment shows coal combustions make the largest contribution to the total risk of PAHs (56.1%), followed by gasoline engine (22.5%) and coke oven (21.4%).

Based on the strong interaction between histidine and copper ions and the signal enhancement effect of gold-labeling carbon nanotubes, an electrochemical sensor is established and used to measure copper ions in river water. In this study the results show that the concentrations of copper ion have well linear relationship with the peak current in the range of 10−11–10−7 mol/L, and the limit of detection is 10−12 mol/L. When using this method to detect copper ions in the Xiangjiang River, the test results are consistent with the atomic absorption method. This study shows that the sensor is convenient to be used in daily monitoring of copper ions in river water.

Cr(VI) is a characteristic soil and groundwater contaminant in the chromite ore processing residue (COPR) disposal regions. Investigation of Cr(VI) adsorption and migration characteristics in topsoils has great significance for the supervision of contaminated sites. The methods of adsorption and soil column leaching experiments were used to study Cr(VI) migration characteristics in this research, and a Cr(VI) contaminated site in Hanqingba region of Baotou was chosen as the study area. Based on the adsorption experiment results, the soil adsorption properties of Cr(VI) were interpreted by the Langmuir and Freundlich adsorption isotherm, and the saturation adsorption capacity of the soil sample for Cr(VI) was 70.4 mg/kg. Cr(VI) migration characteristic in the soils was studied through the tracer and migration experiments. The permeability coefficient of the soil sample was 0.059 m/d, and the dispersion coefficient was 0.0371 cm2/s. The breakthrough curves of Br and Cr(VI) showed that the retardatio...

Diethylhexyl phthalate (DEHP) is considered to be an endocrine disruptor, which unlike other chemicals that have either non-specific (e.g., narcotics) or more generalized reactive modes of action, affect the Hypothalamic-pituitary-gonadal (HPG) axis and tend to have specific interactions with particular molecular targets within biochemical pathways. Responding to this challenge, a novel method for deriving predicted no-effect concentration (PNEC) and probabilistic ecological risk assessment (PERAs) for DEHP based on long-term exposure to potentially sensitive species with appropriate apical endpoints was development for protection of Chinese surface waters. PNECs based on potencies to cause lesions in reproductive tissues of fishes, which ranged from 0.04 to 0.20 μg DEHP L(-1), were significantly less than those derived based on other endpoints or other taxa, such as invertebrates. An assessment of risks posed by DEHP to aquatic organisms in surface waters of China showed that 88.17% and 78.85% of surface waters in China were predicted to pose risks to reproductive fitness of fishes with thresholds of protection for aquatic organisms based on 5% (HC5) and 10% (HC10), respectively. Assessment of risks of effects based on effects mediated by the HPG-axis should consider effects on chronic, non-lethal endpoints for specific taxa, especially for reproductive fitness of fishes.

The riverine phosphorus (P) import resulting from human activities is always a worldwide concern for environmental management due to the effect of eutrophication. In this study, we made modification of the NAPI method to make the results closer to the actual situation. We collected the data of seven major outflow rivers in China to have a comprehensive understanding of P export and P inputs and build the quantitative relationship between them. We estimated the net anthropogenic phosphorus inputs (NAPI), including fertilizer P (Pfert), net food and feed import P and non-food P using by human (Pim+nf), in seven major river basins in China and the corresponding riverine total phosphorus (TP) fluxes. The relationship between NAPI and riverine TP flux was also explored. NAPI in seven river basins presented an obvious uneven distribution. Huaihe River basin showed the highest NAPI of 4005.09 kg P km−2 yr−1 due to its highest intensities of human-activities, and the lowest NAPI was observed in Songhua River basin as 334.36 kg P km−2 yr−1. Pim+nf occupied a larger proportion of NAPI in the Pearl River and Liaohe River basins (> 65%), while Pfert contributed more to NAPI in the other basins (nearly 60%) with an exception of the Yangtze River basin (where Pim+nf and Pfert approximately contributed the same). Different contributions of NAPI components were mainly attributed to the different land uses. The total TP flux of all the seven rivers was 117.10 × 103 t P yr−1, with the highest flux in the Yangtze River (77.42 × 103 t P yr−1), contributed 72.88% to the total TP fluxes in China. Change in riverine TP flux could be well described by NAPI, river discharge, and percentage of lake area in the basin and this provided an effective way to predict TP fluxes in rivers.

The concentrations, chemical availability, distribution, and sources of potentially toxic elements (PTEs) in the soil of Xiangjiang Basin in Hunan Province, China were investigated at 85 sites. The highest mean concentrations of Cd, Cu, Zn, As, and Pb were observed in Hengyang, whereas those for Mn, Co, and Hg were observed in Changde. The pollution index values followed the order: Cd &gt, Hg &gt, Cu &gt, Zn &gt, As &gt, Pb, the mean geo-accumulation index values were in the order: Cd &gt, Pb &gt, Co &gt, Mn. Cd was associated with moderate contaminated level, Hg and Pb were associated with moderate contaminated to uncontaminated level, and Cu, Zn, As, Co, and Mn were associated with uncontaminated level of pollution. Furthermore, 64.5% of Cd was water-soluble and exhibited exchangeable fractions, its chemical availability posed a risk to the ecosystem. Spatial analysis, principal component analysis, and a positive matrix factorization model were used to assess the PTE sources. Four principal components contributed to 88.8% of the 8 PTEs concentrations. Mining, smelting, industrial, and agricultural activities, alongside sewage irrigation, the use of agrochemicals, and vehicular emissions are the possible anthropogenic sources that pollute agricultural products and threaten human health in the Xiangjiang Basin.

Apportion soil heavy metal sources across large-scale regions is a challenging task. The present study developed a modified receptor model to estimate the contributions of various sources to soil heavy metals and the associated health risks at a large scale. A positive matrix factorization model based on a partition computing approach was employed; the entire study area was divided into several zones for the source apportionment and then calculated together, termed partition computing-PMF (PC-PMF). The agricultural soil in Tianjin, China, was chosen for the case study. The PC-PMF results showed that irrigation, atmospheric deposition and sludge application were the main anthropogenic sources, with contributions of 26.60 %, 19.56 % and 2.86 %, respectively. We subsequently combined PC-PMF with a human health risk assessment model (HHRA) to obtain the human health risk of every source category. The natural background was regarded as a major factor influencing human health in the study area, with contributions of 38.03 % for the noncarcinogenic risk and 28.68 % for the carcinogenic risk. The results indicated that PC-PMF performed better at the source apportionment of soil heavy metals than PMF. This study provides a good example of how the spatial variability can be utilized to reduce the uncertainty in source apportionment.

A universal method to evaluate groundwater pollution risk with the site scale has not been established. The groundwater pollution risk is commonly evaluated by overlaying the results of groundwater vulnerability and pollution sources, but this method is inapplicable for contaminated sites. Considering the current supervision demands of groundwater pollution in China, this paper suggests a risk evaluation method for contaminated sites. The present and forecasted groundwater pollutant concentrations and the variation trend of groundwater quality were used to get the risk classes of groundwater pollution. Chromium is one of the most common groundwater contaminants found at industrially contaminated sites. A chromium residue disposal site in Baotou, China was selected as the study area. The groundwater flow model and solute transport model were constructed by MODFLOW and MT3DMS. Based on the simulation results of the numerical model, the groundwater pollution risk of the contaminated site was divided into four classes, and the regulation measures of groundwater pollution were suggested. This study could provide guidance for the environmental supervision and management of contaminated sites.

The soil pollution by heavy metals was characterized in the mine tailings and surrounding soils of an old Pb–Zn mine in Huize County. Three hundred and ninety-six samples of agricultural and non-agricultural soil were analyzed for the total metal concentration by acid digestion and sixty-eight selected soil samples were used to determine the chemical fractionation of heavy metals with the modified BCR sequential extraction method. The pollution index of the heavy metals indices for As, Cd, Cr, Cu, Hg, Pb and Zn of non-agricultural soil and agricultural soils in the study area indicated the spreading of heavy metal pollution. Sequential extraction showed that most of Cd existed in an exchangeable form (31.2 %). The available content of Pb, Cu and Zn was mainly distributed in acid extractable fractions and Fe/Mn oxide fractions (27.9, 30 and 27.2 %), and Hg, As and Cr were mainly associated with residual fractions (90.4, 72.9 and 76.8 %). The risks of heavy metals were also evaluated by the risk assessment code (RAC) and potential ecological risk index, respectively. The results of RAC showed a medium and high risk of Cd (45.6 and 54.4 %), medium risk of Zn (100 %), low and medium risk of Cu (41.2 and 58.8 %), largely no risk of Hg (97.1 %), and mainly low risk of As and Pb (92.6 and 91.8 %). The range of the potential ecological risk of soil was 58.2–1839.3, revealing a considerably high ecological risk in the study area, most likely related to acid mine drainage and the mining complexes located in the area. The results can be used during the ecological risk screening stage, in conjunction with the total concentrations and metal fractionation values, to better estimate ecological risk.

Total-reflection X-ray fluorescence (TXRF) has achieved remarkable success with the advantages of simultaneous multi-element analysis capability, decreased background noise, no matrix effects, wide dynamic range, ease of operation, and potential of trace analysis. Simultaneous quantitative online analysis of trace heavy metals is urgently required by dynamic environmental monitoring and management, and TXRF has potential in this application domain. However, it calls for an online analysis scheme based on TXRF as well as a robust and rapid quantification method, which have not been well explored yet. Besides, spectral overlapping and background effects may lead to loss of accuracy or even faulty results during practical quantitative TXRF analysis. This paper proposes an intelligent, multi-element quantification method according to the established online TXRF analysis platform. In the intelligent quantification method, collected characteristic curves of all existing elements and a pre-estimated background curve in the whole spectrum scope are used to approximate the measured spectrum. A novel hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve-fitting problem, with offline global optimization and fast online computing. Experimental results verify that simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu and Zn, is realized on the online TXRF analysis platform, and both high measurement precision and computational efficiency are obtained.

The objective of the present study was to conduct a probabilistic assessment of risk posed by copper found in the coastal marine environment of China from 2005 to 2012. This was achieved by applying a tiered ecological risk assessment (ERA) approach for characterization of risks of concentrations of copper from nationwide marine water monitoring program. The results show that from 2005 to 2012 the overall trend of hazard quotients (HQs) in the coastal marine environment of China the proportion of locations that exceed a HQ of 1.0 decreased from 64% in 2005 to 31% in 2012. While this indicates an overall improvement of the environment, there still have potential ecological risks in the most of the area, especially for the major gulfs of Liaodong and Bohai Bays and Yellow River Estuary. In addition, probabilities of exceeding the toxicity threshold for 5% of species were 27.6%, 5.4%, 4.9%, 0.8%, 0.4%, 1.0%, 1.8% and 0.12% annually between 2005 and 2012, respectively.

China faces a big challenge of environmental deterioration amid its rapid economic development. To comprehensively identify the contamination characteristics of heavy metals in Chinese soils on a national scale, data set of the first national soil pollution survey was employed to evaluate the pollution levels using several pollution indicators (pollution index, geoaccumulation index and enrichment factor) and to quantify their exposure risks posed to human health with the risk assessment model recommended by the US Environmental Protection Agency. The results showed that, due to the drastically increased industrial operations and fast urban expansion, Chinese soils were contaminated by heavy metals in varying degrees. As a whole, the exposure risk levels of soil metals in China were tolerable or close to acceptable. Comparatively speaking, children and adult females were the relatively vulnerable populations for the non-carcinogenic and carcinogenic risks, respectively. Cadmium and mercury have been identified as the priority control metals due to their higher concentrations in soils or higher health risks posed to the public, as well as, arsenic, lead, chromium and nickel. Spatial distribution pattern analysis implied that the soil metal pollutions in southern provinces of China were relatively higher than that in other provinces, which would be related to the higher geochemical background in southwest regions and the increasing human activities in southeast areas. Meanwhile, it should be noticed that Beijing, the capital of China, also has been labeled as the priority control province for its higher mercury concentration. These results will provide basic information for the improvement of soil environment management and heavy metal pollution prevention and control in China.

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.

The analysis of a large number of multidimensional surface water monitoring data for extracting potential information plays an important role in water quality management. In this study, growing hierarchical self-organizing map (GHSOM) was applied to a water quality assessment of the Songhua River Basin in China using 22 water quality parameters monitored monthly from 13 monitoring sites from 2011 to 2015 (14,782 observations). The spatial and temporal features and correlation between the water quality parameters were explored, and the major contaminants were identified. The results showed that the downstream of the Second Songhua River had the worst water quality of the Songhua River Basin. The upstream and midstream of Nenjiang River and the Second Songhua River had the best. The major contaminants of the Songhua River were chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total phosphorus (TP), and fecal coliform (FC). In the Songhua River, the water pollution at downstream has been gradually eased in years. However, FC and biochemical oxygen demand (BOD5) showed growth over time. The component planes showed that three sets of parameters had positive correlations with each other. GHSOM was found to have advantages over self-organizing maps and hierarchical clustering analysis as follows: (1) automatically generating the necessary neurons, (2) intuitively exhibiting the hierarchical inheritance relationship between the original data, and (3) depicting the boundaries of the classification much more clearly. Therefore, the application of GHSOM in water quality assessments, especially with large amounts of monitoring data, enables the extraction of more information and provides strong support for water quality management.

Owing to the vast territory of China and strong regional characteristic of ozone pollution, it is desirable for policy makers to have a targeted and prioritized regulation and ozone pollution control strategy in China based on scientific evidences. It is important to assess its current pollution status as well as spatial and temporal variation patterns across China. Recent advances of national monitoring networks provide an opportunity to insight the actions of ozone pollution. Here, we present rotated empirical orthogonal function (REOF) analysis that was used on studying the spatiotemporal characteristics of daily ozone concentrations. Based on the results of REOF analysis in pollution seasons for 3 years' observations, twelve regions with clear patterns were identified in China. The patterns of temporal variation of ozone in each region were separated well and different from each other, reflecting local meteorological, photochemical or pollution features. A rising trend for annual averaged of Eight-hour Average Ozone Concentrations (O3-8 hr) from 2014 to 2016 was observed for all regions, except for the Tibetan Plateau. The mean values of annual and 90 percentile concentrations for all 338 cities were 82.6 ± 14.6 and 133.9 ± 25.8 μg/m3, respectively, in 2015. The regionalization results of ozone were found to be influenced greatly by terrain features, indicating significant terrain and landform effects on ozone spatial correlations. Among the 12 regions, North China Plain, Huanghuai Plain, Central Yangtze River Plain, Pearl River Delta and Sichuan Basin were realized as priority regions for mitigation strategies, due to their higher ozone concentrations and densely population.

Electrokinetic experiments were conducted on chromium-residue-contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. The results showed that electrokinetic remediation removal efficiency of chromium from chromium-contaminated soil was significantly enhanced with acidizing pretreatment. The total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] removal rate of the group acidized by citric acid (0.9 mol/L) for 5 days was increased from 6.23% and 19.01% in the acid-free experiments to 26.97% and 77.66% in the acidification-treated experiments, respectively. In addition, part of chromium with the state of carbonate-combined will be converted into water-soluble state through acidification to improve the removal efficiency. Within the appropriate concentration range, the higher concentration of acid was, the more chromium was released. So the removal efficiency of chromium depended on the acid concentration. The citric acid is also a kind of complexing agent, which produced complexation with Cr that was released by the electrokinetic treatment and then enhanced the removal efficiency. The major speciation of chromium that was removed from soils by acidification-electrokinetics remediation was acid-soluble speciation, revivification speciation and oxidation speciation, which reduced biological availability of chromium.

Species sensitivity distribution (SSD) is the most common method used to derive water quality criteria, but there are still issues to be resolved. Here, issues associated with application of SSD methods, including species selection, plotting position, and cutoff point setting, are addressed. A preliminary improvement to the SSD approach based on post-stratified sampling theory is proposed. In the improved method, selection of species is based on biota of a specific basin, and the whole species in the specific ecosystem are considered. After selecting species to be included and calculating the cumulative probability, a new method to set the critical threshold for protection of ecosystem-level structure and function is proposed. The alternative method was applied in a case study in which a water quality criterion (WQC) was derived for ammonia in the Songhua River (SHR), China.

Over the past few decades, numerous concerns have been raised in China over the issue of environmental sustainability. Various soil survey and monitoring programs have been carried out in China to study soil quality, and to provide a scientific basis for environment policy making. This paper provides an overview of past and current soil quality surveys and monitoring activities in China. This paper includes a summary of concerns over background concentrations of elements in soil, and soil environmental standards and guidelines in China. Levels of pollution in urban soil, agricultural soil, and soil in mining and smelting areas were compared using the concentrations and pollution indexes. In addition to soil surveys, soil monitoring is essential to study the data and to examine the effects of contaminants in soils. However, the current soil quality monitoring system was insufficient to accurately determine the soil quality status of soils across China. For accurate soil monitoring in China, it will be necessary to set up routine monitoring systems at various scales (national, provincial, and local scales), taking into consideration monitoring indicators and quality assurance. This is currently an important priority for the environmental protection administration of China. Keywords: Soil pollution, Soil pollution assessment, Soil survey, Soil environmental quality, Soil monitoring, China

Monitoring of status and trends of quality of surface waters is important to assure sustainability of desired structures and functions of aquatic environments. Recently, several sets of legislation worldwide (USA, European Commission, Canada, Australia, South Africa, etc.) have been developed, that consider water bodies as ecological systems, in order to address ecological quality or integrity of watersheds. Current monitoring and assessment of water quality in China, which is still based on amounts of chemical pollutants, such as ammonia and BOD, has been deemed to be insufficient to adequately assess the quality of aquatic environments. Responding to this challenge, China has embarked on a pilot national monitoring program to assess ecological integrities of major watersheds beginning in 2010. The components used in this monitoring and assessment system include hydrology, river morphology, physico-chemical parameters, ecotoxicological aspects, types and numbers of biota and age and growth of fishes. Based on the results of the pilot scheme an ecological integrity index for surface waters will be established; a national coordination and management system, including methods for comprehensive monitoring of ecological integrity of surface waters in China will be initiated.

This paper studies the emissions of SO2 and COD in China using fine-scale, countylevel data. Using a widely used spatial autocorrelation index, Moran’s I statistics, we first estimate the spatial autocorrelations of SO2 and COD emissions. Distinct patterns of spatial concentration are identified. To investigate the driving forces of emissions, we then use spatial econometric models, including a spatial error model (SEM) and a spatial lag model (SLM), to evaluate the effects of variables that reflect level of economic development, population density, and industrial structure. Our results show that these explanatory variables are highly correlated with the level of SO2 and COD emissions, though their impacts on SO2 and COD vary. Compared to ordinary least square regression, the advantages of SLM and SEM are demonstrated as they effectively reveal the existence and significance of spatial dependence. The SEM, in particular, is chosen over the SLM as the role of spatial correlation is stronger in the error model than in the lag model. Based on the research results, we present some preliminary policy recommendations, especially for those high–high cluster regions that face significant environmental degradation and challenge.

Current research on groundwater vulnerability is aimed mainly at groundwater pollution vulnerability (GPV), and the vulnerability of groundwater quantity is seldom considered. It is important to carry out the groundwater vulnerability evaluation for the management of groundwater resources. This paper presents evaluation models and methods for assessing groundwater quantity and pollution vulnerability. The models and methods were used to evaluate the groundwater vulnerability in the plain area of Baotou, Inner Mongolia, China. The groundwater quantity vulnerability was assessed by computing the groundwater recharge rate, and the GPV was evaluated by simulating the migration time for pollutants traveling from ground surface to the aquifer. The research results could provide scientific support for the management of regional groundwater resources, prevention and control of groundwater pollution.

Based on the strong interaction between histidine and copper ions and the signal enhancement effect of gold-labeling carbon nanotubes, an electrochemical sensor is established and used to measure copper ions in river water. In this study the results show that the concentrations of copper ion have well linear relationship with the peak current in the range of 10−11–10−7 mol/L, and the limit of detection is 10−12 mol/L. When using this method to detect copper ions in the Xiangjiang River, the test results are consistent with the atomic absorption method. This study shows that the sensor is convenient to be used in daily monitoring of copper ions in river water.

The Songhua River (SHR) is one of the seven major rivers in China. It feeds into Heilongjiang River, which is the natural border river between China and Russia. The water quality and security of the border river plays an important role in relations of two countries and the economic development for border region. This article collects the papers about researches on organic pollutant in SHR of recent 40 years. With the research study result, this article analyses organic pollutant change trend in terms of detected category, amount and distribution. It shows that the organic pollution is severe and caused negative impact on ecological environment because of industrial development near river bank during 1970–2000. The water quality of SHR has been improved and changed to slight pollution due to the implementation of basin pollution prevention planning in 21st century. The pollutant categories have decreased with lower concentration trend. This study suggests the research orientation for organic pollution of SHR in the future.

Groundwater vulnerability assessment plays a vital role in the utilization and protection of groundwater resources. DRASTIC is one of the most widely used models for groundwater vulnerability assessment. However, the DRASTIC model should be modified based on the local hydrogeological conditions in order to get a relatively accurate result. In this study, Baotou, China was chosen as a case study. The groundwater vulnerability was assessed using DRASTIC at first, but the evaluation results were not consistent with the groundwater quality. So the DRASTIC model was modified based on extension theory and analytic hierarchy process (AHP) method. The extension theory could be used to divide the groundwater vulnerability grades in the DRASTIC model. It is a new attempt to use extension theory and DRASTIC in the assessment of groundwater vulnerability, and the research results show that this method is better for assessing groundwater vulnerability.

The relationships between land use patterns and water quality in trans-boundary watersheds remain elusive due to the heterogeneous natural environment. We assess the impact of land use patterns on water quality at different eco-functional regions in the Songhua River basin during two hydrological seasons in 2016. The partial least square regression indicated that agricultural activities associated with most water quality pollutants in the region with a relative higher runoff depth and lower altitude. Intensive grazing had negative impacts on water quality in plain areas with low runoff depth. Forest was related negatively with degraded water quality in mountainous high flow region. Patch density and edge density had major impacts on water quality contaminants especially in mountainous high flow region, Contagion was related with non-point source pollutants in mountainous normal flow region, landscape shape index was an effective indicator for anions in some eco-regions in high flow season, Shannon&rsquo, s diversity index contributed to degraded water quality in each eco-region, indicating the variation of landscape heterogeneity influenced water quality regardless of natural environment. The results provide a regional based approach of identifying the impact of land use patterns on water quality in order to improve water pollution control and land use management.

Drinking groundwater is a significant pathway for human exposure to heavy metals. To evaluate the health effect of some heavy metals ingestion through the groundwater drinking pathway, the authors collected 35 groundwater samples from the drinking water wells of local residents and the exploitation wells of waterworks in Baotou, China. The monitoring results indicate that the groundwater had been polluted by heavy metals in some regions of the study area. A health risk assessment model derived from the U.S. Environmental Protection Agency was used to determine the noncarcinogenic and carcinogenic effects to residents who drink groundwater. All the respondents in the study area were at potential risk of carcinogenic health effects from arsenic when using the lowest safe standard for carcinogenic risk (1E-06). The hazard quotient values for noncarcinogenic health risk of arsenic exceeded 1 in 14.3% of the sampling wells in the study area. The research results could provide baseline data for groundwater utilization and supervision in the Baotou plain area.

Total reflection X-ray fluorescence has advantages of simultaneous multi-element detection, potential of trace analysis, etc. However, overlapping effects may lead to loss of accuracy or even faulty results in practical quantitative multi-element analysis, especially for trace elements in environmental samples. Conventional approaches consider only partial overlapping effects and are difficult to be generalized. Thus, an intelligent quantitative multi-element determination method is proposed. With a scalable spectral decomposition framework, quantification becomes approximating measured spectra with characteristic curves of possible elements. Particle swarm optimization is used to solve the problem with a heuristic scheme. Trace elements, including K, Cr, Mn, Fe, Co, Ni, As and Pb, are measured simultaneously on the established TXRF analysis platform. Experiments verify that high measurement precision and computational efficiency can both be obtained by adopting the proposed method.

Soil pollution by Cd, Hg, As, Pb, Cr, Cu, and Zn was characterized in the area of the mining and smelting of metal ores at Guiyang, northeast of Hunan Province. A total of 150 topsoil (0-20 cm) samples were collected in May 2012 with a nominal density of one sample per 4 km(2). High concentrations of heavy metals especially, Cd, Zn, and Pb were found in many of the samples taken from surrounding paddy soil, indicating a certain extent of spreading of heavy metal pollution. Sequential extraction technique and risk assessment code (RAC) were used to study the mobility of chemical forms of heavy metals in the soils and their ecological risk. The results reveal that Cd represents a high ecological risk due to its highest percentage of the exchangeable and carbonate fractions. The metals of Zn and Cu pose a medium risk, and the rest of the metals represent a low environmental risk. The range of the potential ecological risk of soil calculated by risk index (RI) was 123.5~2791.2 and revealed a considerable-high ecological risk in study area especially in the neighboring and surrounding the mining activities area. Additionally, cluster analyses suggested that metals such as Pb, As, Hg, Zn, and Cd could be from the same sources probably related to the acidic drainage and wind transport of dust. Cluster analysis also clearly distinguishes the samples with similar characteristics according to their spatial distribution. The results could be used during the ecological risk screening stage, in conjunction with total concentrations and metal fractionation values to better estimate ecological risk.

Understanding the exposure risks of trace metals in contamination soils and apportioning their sources are the basic preconditions for soil pollution prevention and control. In this study, a detailed investigation was conducted to assess the health risks of trace metals in surface soils of Beijing which is one of the most populated cities in the world and to apportion their potential sources. The data set of metals for 12 elements in 240 soil samples was collected. Pollution index and enrichment factor were used to identify the general contamination characteristic of soil metals. The probabilistic risk model was employed for health risk assessment, and a chemometrics technique, multivariate curve resolution-weighted alternating least squares (MCR-WALS), was applied to apportion sources. Results suggested that the soils in Beijing metropolitan region were contaminated by Hg, Cd, Cu, As, and Pb in varying degree, lying in the moderate pollution level. As a whole, the health risks posed by soil metals were acceptable or close to tolerable. Comparatively speaking, children and adult females were the relatively vulnerable populations for the non-carcinogenic and carcinogenic risks, respectively. Atmospheric deposition, fertilizers and agrochemicals, and natural source were apportioned as the potential sources determining the contents of trace metals in soils of Beijing area with contributions of 15.5%–16.4%, 5.9%–7.7% and 76.0%–78.6%, respectively.