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Heavy metal pollution of soil restricts the sustainable use of land and poses risks to human health throughout the world. Changes in the physicochemical properties of soil may increase the mobility of heavy metals in the soil ecosystem and lead to groundwater pollution. In this study, the effects of different salt solutions (NaCl, CaCl2, NaNO3, MgCl2, Na2SO4, and mixed salts) on the release of Cd from soil were investigated by batch desorption tests and the Freundlich isothermal sorption model. Increased concentrations of the salts, except for NaNO3, significantly promoted Cd release (R2 &gt, 0.9, p &lt, 0.01). Under the salt stress, Cd release from the test soils was promoted more by CaCl2 and MgCl2 than by the other salts, and the average desorption rates of eight soil samples at 3.5% salt concentration were 11.15% and 10.80%, respectively, which were much higher than those of NaCl (4.05%), Na2SO4 (0.41%), and NaNO3 (0.33%). Ca2+ and Mg2+ showed better ion exchange capacity than Na+ to promote Cd release, for anions, Cl− formed hydrophilic Cd chloride complexes with Cd in soil. In addition, principal component analysis results revealed that Cd release was mainly influenced by soil texture, cation exchange capacity, and iron–manganese oxide content of the soil. The Cd release level for different soil samples was most closely related to the proportion of fine particles in the soil. The higher the clay content was, the higher the Cd desorption rate.

The catalytic performances of different commercial cobalt oxides(Co x O y , i.e., Co2O3, Co3O4, and CoO) for peroxymonosulfate(PMS) activation in dye degradation were compared in this study. The CoO/PMS system exhibited the highest catalytic oxidation performances with more than 96% methylene blue(MB) removal at 90 min. The concentration of dissolved cobalt ions from CoO was 1.474 mg/L at neutral pH and 5.231 mg/L at acidic pH at 90 min which accounted for the high MB removal and CoO activated PMS homogeneously compared to the associated CoSO4/PMS. Co3O4 and Co2O3 exhibited similar catalytic performances and characteristics. The MB removal in Co3O4/PMS and Co2O3/PMS system were more than 88% at neutral pH and over 64% at acidic pH, respectively, in 90 min. The concentration of dissolved cobalt ions from Co3O4 and Co2O3 was less than 0.018 mg/L at neutral pH and 0.036 mg/L at acidic pH at 90 min. The MB removal achieved by Co3O4/PMS and Co2O3/PMS were approximately three times higher than that achieved by their associated CoSO4/PMS systems and the heterogeneous catalysis played a principal role in the processes. According to scavenger experiments, the contributions of the hydroxyl radicals in the MB degradation were negligible compared to sulfate radicals in the CoO/PMS system. Hydroxyl radicals contributed one-third or more and sulfate radicals were the dominant oxidizing species in the Co3O4/PMS and Co2O3/PMS systems. Co x O y could also effectively activate PMS to generate free radicals for degradation of other dyes. The dyedegradation processes in Co3O4/PMS, Co2O3/PMS and CoSO4/PMS systems followed pseudo-first-order kinetic model and dye degradation rates in different systems were also compared.

The objective of this study is to evaluate the urbanized ecological environment quality with land use classification system (artificial ecological subsystem, water ecological subsystem and continental ecological subsystem). Three land use type ecosystem combined with characteristics of urban ecological environment conditions (space pattern, environment characteristics, biological characteristics, ecosystem service) established the urban ecological environment quality synthetic evaluation index system. Based on the database, this study integrated Delphi, AHP and Integrated Eco-environment Assessment Index Method. The results showed that Beijing Chaoyang district comprehensive urban ecological quality was middle level. Water resources shortage, the total population pressure and urban green spaces shrinkage were negative factors possibly attributable to decrease ecological quality status.

In the environmental event of hazardous release into river, quick and accurate identification of the contamination source is important for emergence response. Generally, given a noisy and finite set of monitoring information, determining the source items (i.e. location, strength and release time) is an ill-posed inverse problem. In this study, a Markov chain Monte Carlo method combined with advection-dispersion equation (ADE) was proposed for the source identification of contamination event in river system based on a Bayesian probabilistic inferential framework. Case study with analytical solution for one-dimensional ADE showed that the proposed methodology was effective and the mean posterior errors for all source parameters were lower than 3%. Case simulation based on two-dimensional ADE with numerical solution obtained similar results and further demonstrated the utility of the proposed approach for source identification. We hope the study will provide a helpful guidance to develop approach for contamination event source identification to support environmental risk management of river system.

An eco-environmental geochemical investigation was carried out in and around the Dexing mining area to determine the concentrations of heavy metals in the surface water, sediments, soils and plants. The main objective of this study is to assess the environmental situation and evaluate the transferring of heavy metals from mining activities into the food chain. Some samples of water, sediment, topsoil and plant were collected along the Lean River in the Dexing mining area. The total concentrations of Cu, Pb, Zn, Cd, and As were determined by AAS, and Hg was analyzed by cold-vapor AAS. Some indices such as ‘contamination degree’, ‘geoaccumulation index’, and ‘biological absorption coefficient’ were used to assess eco-environmental quality. The investigation indicated a highly localized distribution pattern closely associated with the two pollution sources along the Le' an, River bank: one is strong acidity and a large amount of Cu in the drainage from the Dexing Cu mining area; and the other is the high concentrations of Pb and Zn in the effluents released from many smelters and mining, processing and extracting activities in the riparian zone. Results from the investigated localities indicated, at least in part, that some problems associated with environmental quality deterioration should be solved in the future.

Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, water body and stream sediment. An environmental geochemical investigation was carried out in and around the Panzhihua mining and smelting area to determine the extent of chemical contamination in soil and sediment. The main objective of this study was to investigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the study area. The data of heavy metal concentrations reveal that soils and sediments in the area have been slightly contaminated. Geochemical maps of Igeo of each heavy metal show that the contaminated sites are located in V-Timagnetite sloping and smelting, gangues dam. The pollution sources of the selected elements come mainly from dusts resultant from mining activities and other three-waste-effluents. The area needs to be monitored regularly for trace metal, especially heavy metal enrichment.

A total of 31 topsoil samples were systematically collected from the Panzhihua mining area including steel smelting, coal mining, urban and rural districts. A normalization procedure was adopted to establish the environmental geochemical baseline models for this area. By using the above baseline models, the regional geochemical baseline values of As, Cr, Cu, Ni, Pb and Zn were determined. On the basis of the baselines, the enrichment factors were used to analyze the mechanism of trace metal pollution in topsoil from anthropogenic sources, and the results showed that the serious trace metal pollution is caused by human activities in coal mine, iron mine, smelting factory, tailing dam and other industrial districts in the Panzhihua area.

Northern Ordos Cretaceous Basin has abundant mineral resources and now it is facing the problem of lacking water. An understanding of the evolution of the groundwater contributes to resource management. In view of the lake controlling action of groundwater evolution in this area, the paper finds out the relationship between the lakes and groundwater. Remote sensing image data, hydrochemical data and stable isotope data are combined to analyze the hydrochemical processes of the groundwater. The distribution of the lakes shows that more than 80% of the lakes are small ones, and most of them are formed in the depressions. Medium and large ones are formed in the regional drainage. The hydrochemical characteristics of the water in the lakes are Cl- Na type while the hydrochemical characteristics of groundwater varies from HCO 3− Ca· Mg· Na to SO 4− Na along the flow paths. The groundwater have the similar composition of hydrochemical composition of HCO 3− Ca· Mg and stable isotope signatures in Cenozoic group, Luohandong group and Huanhe group, which reveals that groundwater in these three aquifers have close hydraulic connection. The results suggest that the groundwater receives recharge from precipitation, and discharges into the lakes

The potential and existing problem of local water resources development can be directly reflected by the quantification of water resources carrying capacity evaluation index according to the mutual inverse and interactive relationship between optimal allocation of water resources and water resources carrying capacity evaluation. This paper established a multi-objective optimal allocation model through analyzing the characteristics of water resources, calculated regional water resources carrying capacity on this base, applied this method in the evaluation of groundwater resources carrying capacity of 2020 of Baojixia irrigation area in Shaanxi province. The results show that the concept of this method is clear, and this method has very strong practicality and operability, it can provide scientific guiding for sustainable development and utilization of regional water resources.

A pre-research was conducted to validate the availability of using nuatral wetland to control village sewage and improving water quallity in reservior. Removal of COD, TP, TN, NH4-N, As, Cd and Hg by tested natural wetland both in growing period and decaying period was tested. Characteristics of soil and plant in tested wetland were also analyzed. The results showed that the maximum removal by tested wetland is about 40% of TP, 55% of TN, 9.5% of NH4 +-N and 30% of COD in May. In October, TP removal increased, while other parameters removal decreased. Pollutant contents in some of the sampling sites even increased, mainly caused by the high level pollutants from agricultural runoff and poultry plant aside. From this point, natural wetland for wastewater treatment at the studied sites seemed a little difficult and pretreatment of the high level pollutants is important.

A pot experiment was conducted to investigate the potential of removal of pyrene from spiked soils planted with Bidens maximowicziana. The removal of pyrene from the spiked soils planted with B. maximowicziana was obviously higher than that from the unplanted soils. After 50 d, the removal ratio of pyrene in the planted soils was 79%, which was 28% higher than that of the unplanted soils. Pyrene was both accumulated at roots and shoots of B. maximowicziana. The RCFs (root concentration factors) were 1.64–2.20, whereas the SCFs (shoot concentration factors) were 0.8–1.1. Though the plant-enhanced removal of soil pyrene may be the result of plant-promoted microbial degradation, an amount of pyrene was still accumulated in plants. For example, 21.6 mg kg–1 was accumulated in plants when soil pyrene concentration was 121.3 mg kg–1. In addition, the soil dehydrogenase activity, microbial population and phenolic compounds were all improved in planted soils relative to unplanted soil. The increased microbial population and activities of the soil enzymes are presumed to be important for the removal of pyrene.