Ecological risk assessment and source identification for heavy metals in surface sediment from the Liaohe River protected area, China

Risk assessment, geochemical speciation, and source apportionment of heavy metals in sediments of an urban river draining into a coastal wetland

Thirty sediment samples were collected from the Gohar Rood River (Iran) to assess the elemental concentrations, origins, and probable environmental risks in the riverine system. In this study, fifteen elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Cr at all sites were exceeded the SEL (Severe Effect Level) value. Zn, Mn, Co, and Cr showed a moderate level of contamination, based on pollution index (PI), modified pollution index (MPI), and enrichment factor (EF). The modified hazard quotient (mHQ) represented low to extreme severity of pollution for some elements. The multi-linear regression of the absolute principal component score model indicated that largest contributors of Zn, Cu, Pb, Sb, and Mo to the riverine sediment were from agricultural runoff, domestic, and municipal sewage. Based on the modified BCR (the European Community Bureau of Reference) fractionation scheme, Mn, Co, and Zn indicated a medium to high risk to the local environment.

Influence of local geological data and geographical parameters to assess regional health impact in LCA. Tomsk oblast', Russian Federation application case

The research paper is aimed to modify the human health impact assessment of Cr in soils. The current article presents the input of several critical parameters for the human health Impact Score (IS_hum) assessment in soils. The modification of the IS_hum is derived using geological data - results of neutron activation analysis of soils are used in the IS_hum calculation; research area is divided using the watersheds and population size and density. Watersheds reflect the local environmental conditions of the territory unlike the administrative units (geographical areas of the studied region) due to their geological independence. The calculations of the characterization factor value underestimate the influence of the population size and density on the final result. Default characterization factor values cannot be considered during the assessment of the potential human health impact for the big sparsely inhabited areas. In case of very low population density, the result will be overrated and underestimated in the opposite case. The current approach demonstrates that the geographical separation in the USEtox model should be specified. The same approach can be utilized for other geo zones due to the accessibility of this information (area size, population size, and density, geological, and landscape features).

The impact of river sand mining on remobilization of lead and cadmium in sediments - A case study of the Jialing River

Due to the fast pace of urbanization worldwide, industrial sand mining activities have imposed great pressure on the environment, and consequently, these activities have led to serious environmental problems in aquatic ecosystems. However, the current understanding of the effect of sand mining on heavy metal remobilization in river sediments remains incomplete. The present study employed sediment quality guidelines (SQGs) and the sequential extraction (SE) and diffusive gradients in thin films (DGT) techniques to comprehensively investigate the effect of sand mining on the remobilization process of heavy metals in the aquatic system of the Jialing River. The SQGs results indicated that stations (S1 to S4) with sand mining disturbance exhibited Pb and Cd accumulation in surface sediments. Both C_total-Pb (61.78-122.04 mg·kg^-1) and C_total-Cd (0.85-3.96 mg·kg^-1) were higher than CSQGI (60 mg·kg^-1 for Pb and 0.5 mg·kg^-1 for Cd) and TEC (35.8 mg·kg^-1 for Pb and 0.99 mg·kg^-1 for Cd) limitation in most of sand mining stations. Pb and Cd were mainly bounded in the acid-soluble/exchangeable fraction (F1) and oxidizable fraction (F3) of the surface sediments. At the four stations with sand mining disturbance, about 5-10 folds of DGT-labile Pb and Cd were released in deep sediments (-9 to -12 cm), and Pb and Cd exhibited a transport trend from the sediments into the overlying water, while the above phenomenon was not observed at the two stations without sand mining activities. Correlation analysis revealed that DGT-labile Pb and Cd were suitably correlated with the F1 and F3 fractions, indicating that the acid-soluble/exchangeable and oxidizable fractions were the main sources leading to Pb and Cd remobilization in the sediments. A potential mechanism explanation may be that (1) intense sediment stirring could result in remobilization of the weakly bound fraction, which is related to the contribution of the F1 fraction, and (2) Cd/Pb experienced a corelease process with sulfur due to O₂ introduction (elevation of the dissolved oxygen level) attributed to sediment evacuation, which is related to the contribution of the F3 fraction. The above results suggested that sand mining in the Jialing River should be paid high attention to prevent heavy metal pollution in aquatic ecosystem.

Fractionation analysis and risk assessment of potential toxic elements in reservoir sediments in central China

The pollution of potential toxic elements (PTEs) in the environment is a persistent issue and draws public attention constantly. However, there is no study comprehensively assessing the PTE pollution of water supply reservoirs in central China. This study determined the total contents and fractions of seven PTEs in 10 water supply reservoirs of central China, and evaluated PTE pollution risks by adopting various models. The results indicated that PTE pollution in water supply reservoirs was lower comparing that in estuary or river sediments, and Mn (manganese) was the predominant PTE in central China reservoirs. Fractionation analysis revealed that for B1 fraction (exchangeable/acid-soluble fraction) of Mn, Zn (zinc) and B2 fraction (reducible fraction) of Pb (lead) was high, while the effective state portion of Cr (chromium) was small. The monomial potential ecological risk indices and Igeo values were low among most samples, indicating overall modest PTE pollution. However, the results of the individual contamination factor (ICF) suggested that Pb might lead to potential health risks to human beings.

Risk Assessment and Source Identification of Arsenic in Surface Sediments from Caohai Lake, China

Urban freshwaters containing arsenic are facing an increasing problem of eutrophication. This study evaluated the spatial distribution, ecological risk, and origin of As in surface sediments obtained from Caohai Lake, a typical hypertrophic urban lake in China. It revealed that the total As concentration in surface sediments decreased gradually from north to south, consisted with the lake eutrophication status. The average As level was 161 mg/kg, dominated by reducible and oxidisable fractions. The analyses of geoaccumulation index and enrichment factor indicated that As ranged between moderately-to-heavily and heavily contamination, was severely influenced by anthropogenic factors, i.e. industrial discharges and agricultural activities. Risk assessment code and potential ecological risk index results showed moderate to high potential ecological risk could be observed although the current As risk was low, supporting by the experimentally quantified As release data.

Photochemical transformation mechanisms of dissolved organic matters (DOM) derived from different bio-stabilization sludge

Bio-stabilization sludge contains numerous dissolved organic matter (DOM) that could enter aquatic environments by soil leaching after sludge land use, but a clear understanding of their photochemical behavior is still lacking. In this study, we systematically investigated the photoactivity and photochemical transformation of aerobic composting sludge-derived DOM (DOM_ACS) and anaerobic digestion sludge-derived DOM (DOM_ADS) by using multispectral analysis coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results indicated that DOM_ACS and DOM_ADS have a higher proportion of highly unsaturated and phenolic compounds (HuPh)with high DBE_wa, but the different polyphenols (Polyph) abundance of them, causing the different photoactivity between them. DOM_ACS had much higher apparent quantum yields (AQY) for triplet states of dissolved natural organic matter (³DOM*) and hydroxyl radical (•OH) but slightly lower AQY for singlet oxygen (¹O₂) than DOM_ADS under simulated sunlight conditions. As the irradiation time increased, HuPh and Polyph (associated with humic-like substances) contained in DOM_ACS (DOM_ADS) decreased by 12.0% (14.1%) and 3.0% (0.2%), respectively, with concurrent decrease in average molecular weight and aromaticity moieties, resulting in more generation of aliphatic compounds. Furthermore, based on 27 types of photochemical transformation reactions, DOM_ACS containing higher fractions of O_10-15 and N_1-3O_y class preferred dealkyl group and carboxylic acid reactions, whereas DOM_ADS composed of more N₄O_y and S₂O_y fragments preferred oxygen addition and anmine reactions. Consequently, photochemical transformations reduced the Cd (II) ion activity in the presence of DOM_ACS (DOM_ADS). This study is believed to unveil the photochemical transformation of bio-stabilization sludge-derived DOM and its impact on pollutants' fate in the aquatic environment.

Effect of CaO and montmorillonite additive on heavy metals behavior and environmental risk during sludge combustion

Serious pollution is caused by heavy metals (HMs) emission during sludge combustion treatment, but the addition of minerals has the ability to alleviate the migration of HMs to the gaseous state. In this study, HMs (As, Cr, Zn and Cu) behavior, speciation, and environmental risk during sludge combustion with CaO and montmorillonite (MMT) additive was investigated in the lab-scale tube furnace. The results showed that the sludge combustion was mainly determined by volatile matter. In general, CaO inhibited the volatilization of Cr, Zn, and Cu, but promoted As volatilization. MMT inhibited the volatilization of HMs, but the effect was not obvious at high temperatures. Besides, the improvement of retention effect was not found for Cr and Cu with the increase of CaO at 1000 °C, there might exist threshold value for CaO on HMs retention process. Meanwhile, CaO increased acid-soluble fraction of As significantly at high temperatures, decreased residual fraction of Cr by oxidation, converted Zn and Cu to residual fraction. MMT increased the acid-soluble fraction of As and residual fraction of Cr. In view of the HMs environmental risk in ash, the combustion temperature of sludge was necessary to control under 1000 °C and minerals additive amount was needed to manage above 1000 °C.

Ecological risk assessment and sources identification of heavy metals in surface sediments of a river-reservoir system

Heavy metal contamination of river water and sediments is a global issue affecting ecological health. To reveal heavy metals' ecological risks and biological toxicity in the middle and lower Han River (MLHR), sediment samples collected in this area were analyzed based on a modified ecological risk assessment method (NIRI) and a biological toxicity assessment method. Also, Spearman correlation analysis and Positive Matrix Factorization (PMF) methods were applied to identify the potential sources of heavy metals. The results indicated that the heavy metal content significantly exceeded the background concentrations in Hubei Province. The average potential risk of heavy metals at sampling sites was: Cd > Hg > As > Pb > Cu > Zn. Consequently, high biological toxicity occurred along the MLHR due to the heavy metal enrichment. River damming and water diversion significantly enhanced the hydrologic regime variations and ecological risk in the MLHR. Moreover, two possible pollution sources of the MLHR were identified: one is a combined source of traffic pollution, agricultural pollution, and partial industrial pollution consisting of five heavy metals, Pb, Hg, Zn, Cu, and As, the other is an industrial pollution source dominated by Cd and As. This study provides insights into sediment heavy metal pollution management and ecological risk control in the MLHR and similar rivers worldwide.

Analysis and potential ecological risk assessment of heavy metals in surface sediments of the freshwater ecosystem in Zhenjiang City, China

Heavy metals contamination in freshwater ecosystems has drawn attention worldwide. It is necessary to investigate heavy metals content and assess their ecological risk in order to protect the aquatic ecosystems. In this study, we collected surface sediment samples from the freshwater ecosystem of the city of Zhenjiang, in China, in both winter and summer. Then, we analyzed the seasonal and spatial distribution patterns of lead (Pb), chromium (Cr), cadmium (Cd), zinc (Zn), and copper (Cu). The contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), and potential ecological risk (Eri) were jointly used to assess the pollution degree and the ecological risk posed to the freshwater ecosystem by the aforementioned elements. Multivariate statistical analysis, including Pearson’s correlation and principal component analysis and cluster analysis, were used to identify potential sources of the investigated metals in this research area. Study results showed that: (1) the average concentrations values were 1.81 mg/kg and 1.15 mg/kg for Cd, 55.3 mg/kg and 62.2 mg/kg for Cu, 88.0 mg/kg and 52.5 mg/kg for Cr, 27.3 mg/kg and 22.8 mg/kg for Pb, 87.0 mg/kg and 271 mg/kg for Zn, in winter and summer, respectively. Amongst the investigated elements, the average concentrations of Cd, Cu, Cr, and Pb, were above the local background values in winter, whereas, Cd, Cu and Zn concentrations were higher than the background values in Zhenjiang; (2) The CF and EF indicated that Cd had a high contamination degree and a significant enrichment compare to others investigated metals in the surface sediment of in this research area. (3) Cd posed moderate, considerable, or very high ecological risks in different sites, while the other elements (i.e., Cu, Cr, Pb, and Zn) presented a low degree of ecological risk. (4) Multivariate statistical analyses results indicated Pb, Cu, and Zn had similar geochemical characteristics, while, Cd and Cr had significant differences with the above elements. Therefore, Pb, Cu, and Zn probably originate from the same sources, while Cd and Cr might have mixed sources, including both natural sources and human activities. Overall, more attention should be paid to Cd for risk assessment in the current study area. The findings of this study provide fundamental information for the evaluation and management of the heavy metals investigated in the freshwater ecosystem of Zhenjiang.

Spatial-temporal distribution and pollution indices of heavy metals in the Turnasuyu Stream sediment, Turkey

The potential contamination levels and human health risk of heavy metals in sediment of the Turnasuyu Stream in Ordu, Turkey, were evaluated comprehensively by taking seasonal samples from three different locations. The order of the mean heavy metals (HMs) concentrations (mg/kg) were as follows: Fe > Al > Mn > Pb > Zn > Cu > Co > Cr > Ni > Cd > As. All HM levels, except Cd and Pb, were in the minimum enrichment range as assessed by the sediment enrichment factor (EF). Similar low contamination levels for all HM, except Pb and Cd, were also observed when the contamination factor (CF) and geo-accumulation index (I_geo) were taken into account. The low risk of the study area has also been confirmed by the ecological risk index (E_rⁱ) values. The probable human health risk assessment has been performed, and the lifetime cancer risk (LCR) values for adults were found as negligible with values below 10^-6. In addition, the hazard index (HI) and total hazard index (THI) results were both higher in children than in adults. The Pearson correlation coefficient (PCC) revealed the highest correlation between Cd and Pb (0.85). When the ecological indexes and statistical results are evaluated together, it is thought that the presence of HMs in the sediment may be due to lithological reasons as well as anthropogenic activities such as quarrying, municipal, agricultural, and domestic discharges in the region. Mitigation measures should be taken in accordance with the standards within the river basin to prevent the potential risks of pollution.

Pollution characteristics of soil heavy metals around two typical copper mining and beneficiation enterprises in Northwest China

In order to investigate the situation of heavy metal pollution in the heavy metal industry in Gansu Province, a large copper mining province, two large and typical copper mining and beneficiation enterprises with differences in topographic features, climatic conditions, and soil types were selected as the target of this study based on similar ore types and beneficiation processes. Around these two enterprises, geochemical baselines of the six heavy metals were established, while the degree of local soil heavy metal pollution and potential hazards to humans were assessed based on statistical analysis, single-factor and multi-factor index analysis, and health risk evaluation models. In addition, Spearman's correlation analysis and hierarchical cluster analysis were used to explore the intrinsic association between each heavy metal in the two mining industries to reveal the pattern of soil heavy metal pollution in the copper mining and beneficiation industry and to propose targeted measures to improve and prevent soil heavy metal pollution. The results showed that the heavy metal pollution in the soil around Shengxi Mining Co., Ltd. of Subei County (SX enterprise) was higher than that around Yangba Copper Co., Ltd. of Gansu Province (YB enterprise), but the two enterprises had similar patterns of pollution, with an overall medium level of pollution. The carcinogenic and non-carcinogenic risks for children and adults were within acceptable limits for both enterprises. Besides, the correlation between the different heavy metals to similarity in their sources of contamination and the different degrees of association between the soil heavy metals of the two enterprises due to their environmental characteristics.

Pollution, Ecological Risk and Source Identification of Heavy Metals in Sediments from the Huafei River in the Eastern Suburbs of Kaifeng, China

Rivers in urban environments are significant components of their ecosystems but remain under threat of pollution from unchecked discharges of industrial sewage and domestic wastewater. Such river pollution, particularly over the longer term involving heavy metals, is an issue of worldwide concern regarding risks to the ecological environment and human health. In this study, we investigate the long-term pollution characteristics of the Huafei River, an important urban river in Kaifeng, China. River sedimentary samples were analyzed, assessing the degree and ecological risk of heavy metal pollution using the geo-accumulation index and potential ecological risk index methods, whilst Pearson's correlation, principal component and cluster analyses were used to identify the sources of pollution. The results show that heavy metal concentrations are significantly higher than their corresponding fluvo-aquic soil background values in China, and the geo-accumulation indexes indicate that of the eight heavy metals identified, Hg is most prevalent, followed in sequence by Cd > Zn > Cu > Pb > Ni > As > Cr. The potential ecological risk index of the Huafei River is very high, with the potential ecological risk intensity highest in the midstream and downstream sections, where it is recommended that pollution control is carried out, especially concerning Hg and Cd. Long-term sequence analysis indicates that Cu and Pb dropped sharply from 1998 to 2017, but rebounded in 2019, and that Zn shows a continuous decreasing trend. Four main sources for the heavy metal contaminants were identified: Cr, Cu, Ni, Pb, Zn and Hg derived mainly from industrial activities, traffic sources and natural sources; Cd originated mainly from industrial and agricultural activities; whilst As was mainly associated with industrial activities. Thus, special attention should be paid to Hg and Cd, and measures must be taken to prevent further anthropogenic influence on heavy metal pollution.

Heavy metals in lake surface sediments in protected areas in Poland: concentration, pollution, ecological risk, sources and spatial distribution

This paper presents the state and spatial distribution of surface sediment contamination of 77 lakes in Poland by Cr, Ni, Cd, Pb, Zn, and Cu. The analyzed lakes were located within a network of nature protection areas in the territory of the European Union (EU). Spatial distribution of the heavy metals (HMs), factors favoring the delivery/accumulation of HMs in surface sediments, and pollution sources were analyzed. The results indicate the contamination of lake sediments by HMs, but the potentially toxic effects of HMs are only found in single lakes. The spatial distribution of Cr indicates predominant impacts of point sources, while for Pb, Ni, and Zn, the impact of non-point sources. The analysis showed the presence of areas with very high values of particular HMs (hot spots) in the western part of Poland, while a group of 5 lakes with very low values of Ni, Pb, and Zn (cold spots) was identified in the central part of Poland. Principal component analysis showed that presence of wetlands is a factor limiting HMs inflow to lakes. Also, lower HMs concentrations were found in lake surface sediments located in catchments with a higher proportion of national parks and nature reserves. Higher HMs concentrations were found in lakes with a high proportion of Special Protection Areas designated under the EU Birds Directive. The positive matrix factorization analysis identified four sources of HMs. High values of HMs concentrations indicate their delivery from industrial, urbanized, and agricultural areas. However, these impacts overlap, which disturbs the characteristic quantitative profiles assigned to these pollution sources.

Seasonal and spatial variations of ecological risk from potential toxic elements in the southern littoral zone of İzmir Inner Gulf, Turkey

This study aims to investigate the ecological risk level of potentially toxic elements (PTEs) in İzmir Inner Gulf. Samples were taken from 16 stations selected in the southern littoral zone of the gulf for four seasons (winter, spring, summer, and autumn). Multi-element, total organic carbon, chlorophyll-a, biogenic silica and carbonate analyses were carried out. To determine contamination level and ecological risks, some indices (enrichment factor, modified hazard quotient and potential risk analysis, toxic risk index, etc.) were calculated. Mo and Pb show significant anthropogenic enrichment in the inner gulf. These are followed by Cu, Cd, and Zn with moderate accumulation. Risk assessment indices point out that Ni, Cr, and Cd have a serious potential to create risk for ecosystem, and these are followed by As, Hg, Pb, Zn, and Cu. According to the spatial distribution, land use maps, and factor analysis, the Cd, Zn, and Cr increases are localized at the mouth of the Poligon Stream. Pb and Cu accumulate at the mouth of four large streams feeding the eastern part of the gulf. Pb and Cu enrichment is associated with traffic and industrial discharges. While one of the sources of Hg is anthropogenic, another source is eutrophication resulting from benthic and planktonic diatom blooms. While Fe and Mn are added to the gulf via rivers as a result of rock and soil erosion, another source is sediment. Cr, As, and Ni come from anthropogenic and lithogenic sources and immobilized in sediment. CO₃^-2 source is marine (biogenic) and dilutes other immobilized PTEs. It is understood that the peripheral stations rich in allochthonous organic carbon and the stations close to the central area rich in autochthonous organic carbon contribute to the carbon source in question.

Integrating indices based on different chemical extractions and bioaccumulation in Bellamya aeruginosa to assess metal pollution and ecological risk in sediment

Various indices based on metal chemical data are used to evaluate pollution and ecological risk, but the consistency of the assessment results is usually unsatisfactory, and it is unclear if the ecological risk from sediment metals is accurately represented in in situ zoobenthos. Herein, the pollution and ecological risk associated with As, Cd, Cr, Cu, Ni, Pb and Zn in the sediments of two adjacent lakes (Datun (DT) and Changqiao (CQ)) were comprehensively evaluated by integrating metal concentrations, chemical forms and bioaccumulation in Bellamya aeruginosa (B. aeruginosa). The metal concentrations and chemical compositions varied widely in the sediments. Over 50% of the Cd, Pb and Zn in the sediments was present in bioavailable forms, followed by 28% of Cu and less than 25% of As, Cr and Ni. According to the enrichment factor (EF) and concentration enrichment ratio (CER) assessments, Cr and Ni were natural in origin, while the other metals were at minor to extremely high pollution levels, with average EFs of 1.5-77.6 and CERs of 1.1-113.4. The pollution levels for Cd, Cu and Pb from the EF and CER assessments were similar, while those for As and Zn were higher according to CER than EF (p = 0.05), likely due to the baseline underestimation associated with the potential diagenetic remobilization of bioavailable metals. The ecological risk index (Er), sediment quality guidelines (SQGs) and risk assessment code (RAC) showed a high eco-risk for Cd, while no similar risk was found for the other metals. By integrating risk indices with the chemical forms and pollution levels of metals, we deduced high eco-risks for As and Pb and moderate eco-risks for Cu and Zn in DT Lake and moderate eco-risks for As, Pb and Zn in CQ Lake. The other metals in the sediments of the two lakes presented low eco-risks. No significant positive correlations (p = 0.05) between metal accumulation in B. aeruginosa and the indices of pollution and eco-risk were observed except for the case of As, implying that measuring the metal concentrations in B. aeruginosa would not accurately characterize the metal pollution and ecological risk of sediments.

Assessing the environmental risk and mobility of cobalt in sediment near nonferrous metal mines with risk assessment indexes and the diffusive gradients in thin films (DGT) technique

The Jialing River is the tributary of the Yangtze River with the largest drainage area. In recent years, the Jialing River has suffered a series of environmental problems, such as discharge of industrial effluent and sand mining activities, which have severely threatened the aquatic ecosystem of the river. In the present study, we employed risk assessment indexes, sequential extraction and the diffusive gradients in thin films (DGT) technique to assess environmental risks and study the remobilization of cobalt (Co) in sediments. The potential ecological risk index and risk assessment code results demonstrated that Co may pose a low environmental and ecological risk to the local aquatic environment. However, BCR sequential extraction showed that the sum of the F1, F2 and F3 fractions of Co still accounted for over 50% of the Co in the study areas, indicating that sediments may be a source of Co release. The DGT results showed an increasing trend for DGT-labile Co in deep sediments (-8 cm to -12 cm), and the calculated flux values ranged from 0.08 to 15.54 ng cm²·day^-1, indicating that Co tends to transfer across the sediment-water interface at all sampling sites. Correlation analysis showed that F1-Co, F2-Co and F3-Co are the fractions readily captured by DGT and can be used for predicting Co remobilization in sediment. Sand mining activities contribute substantially to the release of Co from the F1 and F3 fractions as a result of strong stirring of sediments and introduction of oxygen into the sediments. The reductive dissolution of iron (Fe) and manganese (Mn) hydroxides or oxides causes the release of Co and Fe/Mn in the sediment, which leads to Co release from the reducible fraction. The above work suggests that sand mining in the Jialing River should be reasonably regulated to prohibit illegal sand mining activities.

Contamination and source of metals in surface sediments from the Nandu River of Hainan Island, China

Concentrations of eight metals, organic carbon (Corg), and eight oxides were measured in 33 river sediment samples from the Nandu River. Sediment quality guidelines (SQGs) showed no severe pollution at all stations. However, according to the geo-accumulation index (Igeo), enrichment factor (EF), and potential ecological risk index (EI and RI), As and Cd were the primary pollutants in the survey area and caused low to moderate potential ecological risk. The positive correlations between Al₂O₃, TFe₂O₃, Mn, Corg, and metals indicated that clay, FeMn oxides, and organic carbon content were the main factors for metal accumulation in the study area. From the results of correlation (CA) and principal component analysis (PCA), we inferred that Cr, Ni, Cu, and Zn were mainly from natural sources, while As, Cd, Hg, and Pb were from anthropogenic activities in the Nandu River basin. This was the first study of metal pollution in the surface sediments of the Nandu River, which will serve as a reference for future research.

Pollution Levels and Risk Assessment of Heavy Metals in the Soil of a Landfill Site: A Case Study in Lhasa, Tibet

As an important ecological security barrier in China, the ecological environment of Tibet has aroused widespread concern domestically and overseas. Landfills are a major solid waste treatment approach in Tibet but also cause severe environmental pollution. To date, there are no studies related to the pollution risk of landfills in Tibetan areas. This study investigated the pollution levels, ecological risk, health risk, and possible pollution sources of eight heavy metals in the soils around a landfill site in Lhasa, Tibet. The results indicated that the concentrations of heavy metals in soil were relatively low, only cadmium (Cd), arsenic (As), copper (Cu), chromium (Cr), zinc (Zn), nickel (Ni), and lead (Pb) were 1-2 times higher than the corresponding background value. The values of the single pollution index and geo-accumulation index show that the study area is most seriously polluted by Cd and As. Based on the Nemerow pollution index and the pollution load index, over 83.3% and 8.33% of soil sampling sites had light and moderate contamination levels. According to the results of potential ecological risk evaluation, the potential ecological risk of heavy metals in soil was very low, and only one out of the 72 sampling sites exhibited considerable ecological risk. Cd, As, and mercury (Hg) served as the dominant ecological risk contributors and contributed over 45.0%, 14.1%, and 18% of the ecological risk. The results of the health risk evaluation showed that adults have a higher risk of cancer (1.73 × 10^-5), while the non-carcinogenic risk for adults was low. Waste disposal activities and construction activities have a significant influence on soil heavy metal concentrations, causing a higher pollution level in the southeast part of the landfill site in Lhasa.

Partitioning behavior and ecological risk of arsenic and antimony in the sediment-porewater profile system in the Three Gorges Reservoir, China

Arsenic and antimony are widely distributed toxic metalloids in aquatic environments. However, their partitioning behaviors in the sediment profile remain not well understood. Here, partitioning behaviors, diffusive fluxes, as well as the ecological risks of As and Sb in the sediment-porewater profile system in the tributaries of the Three Gorges Reservoir (TGR) were investigated. As and Sb showed markedly different spatial variations in the longitudinal profiles of both porewater and sediment samples. Specifically, the concentration of As showed an accumulation trend with depth, while that of Sb showed a relatively complicated trend. Further, As showed lower sediment-porewater partitioning coefficient (K_d) values, suggesting that it had a relatively lower sediment affinity and a higher mobility than Sb. Its residual fraction (30%-60%) was also lower than that of Sb. This phenomenon could be attributed to the chemical fractions of the trace metals and the pH value of the sediments. Furthermore, the K_d values corresponding to As were influenced by both the residual fraction (r = 0.338, p < 0.05) and the exchangeable fraction (r = -0.643, p < 0.01), while those corresponding to Sb were only influenced by pH. Additionally, even though these two trace metals showed low ecological and mobility risks, the diffusive fluxes at the sediment-water interface suggested that the sediment acted as a source of As and a sink for Sb relative to the overlying water. This study indicated that As and Sb had different partitioning behaviors and release risks in the sediment-porewater profile system, enhanced the understanding the transport and fate of As and Sb in the aquatic environment.

Study on spatial distribution, potential sources and ecological risk of heavy metals in the surface water and sediments at Shanghai Port, China

Heavy metal concentrations in surface waters and sediments of Shanghai port were measured to analyze the spatial distribution characteristics, sources and pollution degrees. The southern Shanghai port was heavily polluted by Cd, Pb, Cr and Cu in water, and the concentrations of Pb, Hg and Zn in sediments exceeded Effects Range Low. Cu, Pb, Cd and Cr in water were positively correlated in group, and they probably derived from industrial and domestic sewage, fossil fuel burning and vehicular pollution and represented 82.47 % of the contribution. Zn, Hg and As contaminations represented industrial and agricultural effluent sources and accounted for the remaining 17.53 %. Heavy metal pollution of Yangshan Port water was at high pollution, and the remaining sites were at low pollution. Most of the sampling sites were at moderate ecological risk in sediments, and the pollution of Cd, Hg and Zn were serious.

Potential Sources of Heavy Metals in Sediments of an Urban‒Agricultural Watershed and Relationship with Land Use Using a Statistical Approach

This study verified pollution levels through evaluation of the Sediment Quality Guidelines (SQGs), pollution load index (PLI), and potential ecological risk index (PERI) by analyzing the concentrations of heavy metals in sediments of an urban‒agricultural watershed in the Yeongsan River basin, South Korea. Statistical analyses were performed to determine the relationships between pollution levels and land use, and potential sources of pollution were identified. For spatial distributions, Pb, Zn, Cu, Cd, and Hg concentrations were highest at mid-upstream, but As, Cr, and Ni concentrations were similar at most sites. The polluted sites, which showed the potential toxicity toward benthic organisms in comparison to SQGs, were most frequently observed at mid-upstream. Moreover, PLI and PERI evaluations also confirmed levels of high anthropogenic pollution and the potential ecological risk at mid-upstream. The mid-upstream sites with high heavy metal pollutions showed high correlations with urban land use, which showed the highest distribution, implying a close relationship with anthropogenic impacts such as high population density and industrial complexes. Statistical analyses also confirmed that high heavy metal concentrations in the mid-upstream were closely related to urban land use. These findings suggest that urban areas are highly likely to cause anthropogenic heavy metal pollution in sediments as point or non-point sources such as domestic sewage and industrial wastewater flow into rivers.

Seasonal behavior and accumulation of some toxic metals in commercial fishes from Kirtankhola tidal river of Bangladesh - A health risk taxation

Contamination of fish with heavy metals (Heavy metals) is one of the most severe environmental and human health issues. However, the contamination levels in tropical fishes from Bangladesh are still unknown. To this end, the evaluated concentrations of arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in 12 different commercially important fish species (Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Glossogobius giuris, Pseudeutropius atherinoides, Polynemus paradiseus, Sillaginopsis panijus, Corica soborna, Amblypharyngodon mola, Trichogaster fasciata, and Wallago attu) were collected from the Kirtankhola River assess human health risk for the consumers, both in the summer and winter seasons. Toxic metals surpassed the acceptable international limits in P. atherinoides, P. paradiseus, S. panijus, C. soborna, and W. attu. The target hazard quotient (THQ) revealed that non-carcinogenic health effects (HI < 1) for children and adults, and the carcinogenic risk (CR) indicated safety. Results show that children are more susceptible to carcinogenic and non-carcinogenic hazards from higher As. The multivariate analysis justified that heavy metals were from anthropogenic actions. The lessening of toxic metals might need strict rules and regulations as metal enrichment would continue to increase in this tidal river from both the anthropogenic and natural sources.

Evaluation of metal accumulation in Terme River sediments using ecological indices and a bioindicator species

Freshwater resources are hotspot areas for sustainable water use. Surface sediment samples from four stations in Terme River were collected seasonally between April 2019 and January 2020. Sample collection from 0 to 10 cm depth of the riverbed was carried out with an Ekman Dredge Grab. Cu, Pb, Zn, Ni, Mn, Fe, Co, As, Cr, Cd, and Al concentrations were determined with an inductively coupled plasma-mass spectrometry (ICP-MS). The percentage of organic matter in the sediment was evaluated by the combustion method. pH measurements were made with a pH meter. The concentrations of elements measured are listed in descending order as follows: Fe > Al > Mn > Cr > Cu > Zn > Ni > Co > Pb > As > Cd. Enrichment factor (EF), contamination factor (CF), and geo-accumulation index (I_geo) are the most commonly used tools to determine whether elements are of natural origin or anthropogenic origin. According to average EF values, the metals are listed as follows: Cd > Cu > Co > Fe > Cr > Pb > Mn > Zn > Al > Ni > As. The CF and I_geo values are listed as follows: Cd > Cu > Co > Fe > Cr > Pb > Mn > Zn > Al > Ni > As. According to EF results, Cd and Cu originate from human activities. The CF and I_geo indicate minimal enrichment for all metals. Potential ecological risk (PERI), pollution load (PLI), modified hazard quotient (mHQ), ecological contamination (ECI), and toxic risk indices (TRI) indicate low risk in the region. Human health risk indices also show that carcinogenic and noncarcinogenic risks are low. In the bioaccumulation evaluation performed on Myriophyllum spicatum species, it was determined that the plant accumulated Mn, Co, Ni, Cu, Zn, As, and Cd. These results show that Myriophyllum spicatum can be used as a bioindicator.

Risk assessment of heavy metals in suspended particulate matter in a typical urban river

Suspended particulate matter (SPM) is a major source of contamination in urban rivers as it serves as a carrier for pollutants, such as heavy metals. In this study, the Beiyun River, northern China, was used as a case study to determine the characteristics of SPM-associated heavy metal spatial distribution, to evaluate the potential ecological risks and identify heavy metal sources. The concentrations of seven heavy metals and other associated indicators (TC, TN, TP, and OM) were measured at 12 sites and analyzed by Pearson correlation (PC) and principal component analyses (PCA). The average concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb were 70.72, 27.88, 31.35, 115.70, 27.77, 0.23, and 29.62 mg/kg, respectively, with significant spatial differences occurring between some elements. Igeo values established the ranked order of heavy metal pollutant concentrations in SPM as As > Cd > Zn > Cu > Pb > Cr > Ni. [Formula: see text] analysis demonstrated that the ranked order of potential ecological risk from the seven metals was Cd > As > Cu > Pb > Ni > Cr > Zn. Potential ecological risk index (RI) results confirmed the high potential ecological risk in the study area. Among the measured heavy metals, Cd represented the highest pollution risk, as shown by its highest [Formula: see text] value. Correlation analysis (CA) showed that Zn had a strong correlation with Cu and Pb. Significant positive correlations were found between TC, TN, TP, and Cu. Three element pairs, Zn-Cd, Cr-Cu, and Cr-Ni, were also found to have strong correlations. Zn, Cu, and Ni were mainly introduced by human activities including urban industrial sewage discharge (such as metallurgy and electroplating industrial wastewater), agricultural drainage, and landfill wastewater, while Cr mainly originated from natural processes like mineral weathering and atmospheric precipitation. This information on the concentration, risk, and sources of SPM in Beiyun River provides an important reference for the reduction of heavy metal pollution in SPM in a typical river in the Haihe River Basin (China).

Coastal reclamation mediates heavy metal fractions and ecological risk in saltmarsh sediments of northern Jiangsu Province, China

Coastal reclamation has created enormous extra land for the rapidly growing economy, but it has also caused serious environmental pollution problems and threatened the sustainable development of coastal areas. However, there are few studies focusing on the distribution patterns, geochemical speciation and ecological risks of heavy metals along the land-to-sea belt, as well as the differences between reclamation and non-reclamation. Here, we collected 69 sediment samples from four sediment types along the land-to-sea sampling belts in the reclaimed and non-reclaimed tidal flats of Jiangsu, China. Geochemical speciation and contents of heavy metals were determined to investigate their spatial distributions, ecological risks and effect factors. Results showed that As, Cd, Cr and Ni in the sediments posed considerable or moderate ecological risk according to the Ontario guidelines and sediment quality guidelines (SQGs) of USEPA, but they were lower than the SQGs of China. Higher geoaccumulation index and potential ecological risk index suggested that the sediments were moderately to heavily polluted by Cd and As. Generally, reclaimed sediments exhibited higher metal pollution levels. Additionally, reclaimed areas showed a unimodal pattern of metal content along the direction of land-to-sea, suggesting that Spartina alterniflora could accelerate the deposition and accumulation of metal pollutants caused by reclamation, and ultimately control the transfer of terrigenous metals to marine environment. We found that residual fraction was the dominant geochemical fraction for the metals determined. Reclamation processes have changed the composition of heavy metal fractions, especially Cd, Pb, Zn, and Ni. Approximately 20% of Cd existed in the acid extractable/exchangeable fraction and posed medium ecological risk according to the risk assessment code. The principal component analysis and correlation matrix further indicate that organic matter and particle size of sediment could be the major factors regulating the metal distribution, and Cd and Zn might be anthropogenic sources.

Heavy Metals in Sediments and Greater Flamingo Tissues from a Protected Saline Wetland in Central Spain

Aquatic ecosystems often act as sinks for agricultural, industrial, and urban wastes. Among potential pollutants, heavy metals can modify major biogeochemical cycles by affecting microorganisms and other biota. This study assessed the distribution and concentration of heavy metals (Cd, Hg, Cu, Pb, and Zn) in Pétrola Lake, a heavily impacted area in central Spain where the greater flamingo Phoenicopterus roseus breeds. This study was designed to determine the concentration and identify the potential sources of heavy metals in Pétrola Lake protected area, including sediments, agricultural soils, and tissues of the greater flamingo. A six-step sequential extraction was performed to fractionate Cu, Pb, and Zn from lake sediments and agricultural soil samples to gain insight into different levels of their bioavailability. Our results showed that Pb and Cd accumulated in lake sediments and agricultural soils, respectively, most likely derived from anthropogenic sources. Multivariate analysis revealed differences between these (Pb and Cd) and the remaining studied elements (Cu, Hg, and Zn), whose concentrations were all below the pollution threshold. Lead pollution in sediments was apparently dominated by organic matter binding, with fractions up to 34.6% in lake sediments. Cadmium slightly accumulated in agricultural soils, possibly associated with the use of fertilizers, but still below the pollution thresholds. In the flamingo samples, low bioaccumulation was observed for all the studied elements. Our study suggests that human activities have an impact on heavy metal accumulation in sediments and soils, despite being below the pollution levels.

Extraction of Metals from Polluted Soils by Bioleaching in Relation to Environmental Risk Assessment

Environmental pollution has particular implications for the whole geosystem and increases the global risk to human and ecological health. In this regard, investigations were carried out on soil samples to perform the quality status assessment by determining: pH, texture, structure and metal concentration, as well as carrying out an assessment of anthropogenic activity by determining pollution indices: C_f (contamination factor), C_d (degree of contamination), PLI (pollution load index), E_r (ecological risk index) and PERI (potential ecological risk index). Analyses on soil samples showed high concentrations of metals (Cu: 113-2996 mg kg^-1; Pb: 665-5466 mg kg^-1; Cr: 40-187 mg kg^-1; Ni: 221-1708 mg kg^-1). The metal extraction experiments were carried out by bioleaching using Thiobacillusferrooxidans, microorganisms at different amounts of bioleaching solution (20 mL and 40 mL 9K medium) and a stirring time of up to 12 h. The results on the degree of contamination, pollution loading index PLI (2.03-57.23) and potential ecological risk index PERI (165-2298) indicate that the soils in the studied area have a very high degree of pollution. The decontamination procedure by bioleaching showed a decrease, but at the end of the test (12 h), the followed indices indicate high values, suggesting that bioleaching should continue. The depollution yield after 12 h of treatment is, however, encouraging: Cu 29-76%, Pb: 10-32%, Cr: 39-72% and Ni 44-68%. The use of yield-time correlation equations allows the identification of the optimal exposure time on the bioleaching extraction process to obtain optimal results. The aim of the research is to determine the soil quality, soil environmental risk, extraction of metals from polluted soils by bioleaching and to identify influencing factors in achieving high remediation yields.

Source-specific ecological risk assessment and quantitative source apportionment of heavy metals in surface sediments of Pearl River Estuary, China

In this study, surface sediments of the Pearl River Estuary were collected from 29 stations and investigated the spatial distribution, pollution level, quantitative source apportionment, and source-specific ecological risk of 10 heavy metals. The mean concentrations followed the order of Mn > Zn > Cr > Cu > Ni > Pb > As > Co > Cd > Hg. In terms of spatial distribution, it showed that the heavy metals were enriched in the inner Pearl River Estuary with 'extremely high' level of Hg, whereas, Cd and Zn posed 'moderate to high' contamination potential. We apportioned four main sources using positive matrix factorization model, in which natural geogenic and industrial manufacturing sources accounted for 36.84% and 27.11% of the total, respectively. However, the source-specific risk assessment suggested that mixed anthropogenic sources were the main contributors, and ecological risks were strongly affected by anthropogenic imports from the surrounding cities.

Concentration, Health Risk, and Hydrological Forcing of Heavy Metals in Surface Water Following Water-Sediment Regulation of the Xiaolangdi Dam in the Yellow River

Water and sediment regulation aimed at aquatic ecosystems and preserving reservoir capacity to minimize the negative consequences of dams can fundamentally change the distribution of heavy metals (HMs) in the reservoir and downstream reaches. However, the effects of water and sediment regulation on variation in HMs are still poorly understood. In this study, the variations in concentration, contamination, human health risk, potential sources, and influencing factors of the metalloid As and HMs (Cr, Hg, Ni, Pb, and Zn) in surface water in the reservoir and the downstream reach of the Xiaolangdi Dam (XLD) following the operation of the water-sediment regulation scheme (WSRS) were determined. These results indicate that HM concentrations in the two post-WSRS seasons were much lower than the water quality standards, but were significantly increased over time due to the trapping effects of the XLD (p < 0.05, except for Zn). However, As concentration in the reservoir was significantly lower than that observed in downstream reaches, likely due to anthropogenic input from agricultural activities. Meanwhile, HM concentrations varied with distance to the dam, which displayed a distinct accumulation closer to the dam in the post-WSRS II season. The contamination of HMs, the carcinogenic risk of exposure to As, and the noncarcinogenic risks associated with exposure to Hg, Ni, Pb, and Zn via the direct ingestion pathway of drinking water were all within acceptable levels following the WSRS, but increased over time. The carcinogenic risk of Cr in the post-WSRS II season was at an unacceptably high level, particularly at sites near the dam. Hydrological characteristics (water level and flow rate) were the dominant factors in determining the distribution of HMs. These results can provide new insight for a better understanding of the variations in HMs following the water and sediment regulation practices, and guide future management in regulating the trapping effects of dams.

Spatiotemporal changes of eutrophication and heavy metal pollution in the inflow river system of Baiyangdian after the establishment of Xiongan New Area

Pollution in inflow rivers seriously endangers the water environment in downstream lakes. In this study, an inflow river system of the Baiyangdian-Fuhe river system (FRS) was investigated to display timely pollution patterns of eutrophication and heavy metals after the establishment of Xiongan New Area, aiming to reveal the weak parts in current pollution treatments and guide the further water quality management. The results showed that the pollution of eutrophication was worse than the heavy metals in FRS, with serious eutrophic parameters of ammonia nitrogen (NH₄ ⁺-N) and chemical oxygen demand (COD). There were greatly spatiotemporal variations of the pollution in FRS. (1) Concentrations of NH₄ ⁺-N and total phosphorus were all higher in summer and autumn, whereas, COD contents were higher in spring; the water quality index (WQI) of eutrophication linearly increased along FRS in summer and autumn, with pollution hotspots around the estuary area. (2) The pollution levels of plumbum exceeded cadmium (Cd) and chromium (Cr) but without strongly spatiotemporal changes; however, Cd and Cr in the town area and Cd in spring showed higher concentrations; the WQI of heavy metals showed single peak curves along FRS, with significantly higher values around the town area. Additionally, the four potential pollution sources: domestic sewage, traffic pollution, agricultural wastewater and polluted sediments were identified based on the pollution patterns and pollutant associations. These findings demonstrated current treatments failed to eliminate the pollution in some hotspots and periods, and the in-depth understanding of the pollution spatiotemporal patterns in this study, especially the pollution hotspots, serious periods and potential sources, are crucial to furtherly develop spatiotemporally flexible pollution treatment strategies.

Assessment of heavy metals in surface water, sediment and macrozoobenthos in inland rivers: a case study of the Heihe River, Northwest China

Long-term retention and accumulation of heavy metals in surface water and sediment pose a great threat to the sustainable development of aquatic ecosystems and human health. In this research, macrozoobenthos, and surface water and sediment heavy metal (Mn, Cr, Cu, Ni, Pb, Zn, Cd, and As) samples were collected from 23 sites in the upper and middle reaches of the Heihe River in the summers of 2019-2020. The interrelationships between heavy metals and macrozoobenthos were analyzed by Pearson correlation analysis and redundancy analysis (RDA), and the contamination level and potential ecological risk of the heavy metals in surface water and sediments were assessed by comprehensive pollution index (WQI), single potential ecological risk index ([Formula: see text]), and sediment quality guideline-quotient (SQG-Q), respectively. The results showed that the level of heavy metal pollution in the surface water of the Heihe River was extremely low, but the contents of Mn and Pb exceeded the third class of surface water environmental quality standards (GB 3838-2002). The spatial distribution of heavy metals in surface sediments were significantly different, and the average concentration of 8 heavy metals exceeded the background values of Gansu Province. Meanwhile, the pollution level of heavy metals in surface sediments was high pollution, and the ecological risk level was moderate risk. Combining [Formula: see text] and SQG-Q evaluations showed that Cd, Ni, and Cr were the main ecological risk factors. In addition, the distribution coefficients of Cr and Cd were low, indicating that Cr and Cd were easily released from the surface sediments, causing secondary pollution. In terms of the source of the heavy metals, Cu, As, Zn, Cr, and Ni mainly came from industrial and agricultural wastewaters, Pb was from the mining industry and natural sources, and Mn and Cd mainly came from tailings and their landfill leachate. Basommatophora and Araneae can be used as potential indicator organisms for heavy metal pollution in surface water, and Basommatophora, Coleoptera, Hemiptera, and Araneae can be used as indicator species for heavy metal pollution in surface sediments. The study showed that macroinvertebrate community characteristics had a sensitive response to heavy metals in the surface waters and sediments of the Heihe River, which can be used to evaluate the pollution status of heavy metals in inland rivers.

Heavy metal toxicity, ecological risk assessment, and pollution sources in a hydropower reservoir

Heavy metal (HM) toxicity, ecological risk, and pollution sources were analyzed using the pollution indexing and statistical methods in the Three Gorges Reservoir (TGR). The average concentration of HM increased in the order of Cr < Ni < As < Cd < Cu < Mn < Pb < Zn < Al < Fe during the recharge period and Cd < Cr < Ni < As < Cu < Pb < Mn < Zn < Al < Fe during the discharge period. Significant spatial variations of Pb, Zn, Cd, As, Mn, Ni, Cr, and Cu were observed at the upstream and downstream sampling sites. Pb sharply increased during the recharge period, ranges (6.93 -148.62 μg/L) and exceeded WHO and USPEA standards limit. HPI, HEI, Cd, WPI indicated low pollution and moderate pollution with the strong influence of Pb and Cd in the discharge and recharging period, respectively. HTML values are below the permissible toxicity load except for Pb. The Pb toxicity removal percentage is 56.47%, suggesting that the lead's toxicity level is high in TGR and requires the removal process. Ecological risk index values indicated that pollution is low in TGR. The potential ecological risk indexes (RI) of 9.07 and 31.60 were obtained for the discharge and recharge period, respectively, indicating low potential ecological risk from heavy metals in TGR. However, RI values revealed that (Pb, Cd, As Cr Ni, Cu Zn, and Mn) were the most ecological risk HMs in TGR. A significant ecological risk of Pb and Cd distribution was observed across the TGR. Multivariate statistical results found that Pb, Cd, Zn, Mn, Ni, As, Cr, Cu mainly originate from industrial wastewater, mining, metals processing, and agricultural runoff. Fe and Al were mainly from bedrock weathering. Pb, Cd, Zn HMs are a threat to the reservoir ecosystem. This study delivered a current status of HM pollution, toxicity, ecological risk, and pollution sources, indicating a vital insight into HM pollution and water security management in the Three Gorges Reservoir.

A scientometric analysis of agricultural pollution by using bibliometric software VoSViewer and Histcite™

While modern agriculture brings more food to people, it causes environmental pollution as well. Agricultural pollution has attracted extensive public attention. A lot of reviews on agricultural research were conducted from different research aspects, but there is a lack of work on analyzing the research trend from large volumes of publications in the field of agricultural pollution. In the present work, a scientometric analysis of agricultural pollution was conducted to fill the gap by using the software of VoSviewer and HistCite™. The datasets are collected from the core database of Web of Science from 1991 to 2019, totally 1338 records on the topic of agricultural pollutions. In most years (1996, 1999, 2002, 2006, 2009, 2011, and 2013), the total local citation score (TLCS) and total global citation score (TGCS) have coincident peaks. Zhang, Ju, and Zhu have the highest TLCS and TGCS. In terms of institutes, Chinese Acad Sci and China Agr Univ are the leading institutes in this field. The Univ Calif Davis, INRA, and USDA ARS have very high global impacts. From the research hot topics, the representative words include "soil," "agriculture," "contamination," "environment," "lead," and "balance." Representative words like "heavy-metals," "groundwater," "land-use," and "water" are emerging in the latter time period. Five leading research co-cited reference clusters are identified, including environment management, underground water, monitoring and alarming for the agriculture-environment standards, intrinsic mechanism to the circulatory system, and ecology system and land use. The recent trend is revealed from the bibliographical-coupling network, focusing on classical and old-fashion research, like pollution chemicals including N management, pesticides, and heavy metal. This work provides a holistic picture on the research in the field of agriculture pollution.

Identification of toxicity factors and causal analysis of toxicity in surface sediments from Liaohe river basin, Northeast China using an effect guidance strategy

Sediments play a pivotal role in maintaining the aquatic ecological status of rivers. However, the determination of the key toxicants that consider the combined effects of all sediment-related contaminants are still challenging and necessary for an appropriate sediment risk assessment. The effects of sediments on aquatic organisms have been reported in Liaohe River, but their key toxicity factors are not well known. To determine the key toxicity factors, twenty-six surface sediment samples from Liaohe River tributaries in Northeast China were collected. Acute toxicity test of midge larvae results showed that 6 of 26 tributaries had obvious toxic effects, with survival rates of 37%-57% (p < 0.05). The masking test showed that the main pollutants in the surface sediments of T7 and T16 were metals, that of T8 was an organic pollutant, those of T19 and T26 were organic pollutants and ammonia, and those of T17 were heavy metal and ammonia. Chemical analysis showed that the relatively high concentrations of ammonia were only presented in surface sediments of T17, T19, and T26, with PTU of 1.5, 1.2 and 1.1, respectively, whereas heavy metals were markedly high in surface sediments from T7 and T16, with PTU of 0.92 and 0.61, respectively. Interestingly, the observed toxicity in surface sediments agreed with the toxicity predicted by chemical analysis Moreover, the significant correlation between the survival and volume ratio of the sediment and overlying water confirmed ammonia nitrogen was key toxicity factor in T17, T19, and T26, whereas Cu was the key toxicity factor in T7 that cause the biological toxicity. In conclusion, the major toxic factors of ammonia and copper in the sediments were identified. Moreover, our study suggested that effect guidance strategy was an effective method for sediment quality assessment.

Distribution and Accumulation of Trace Elements in Organs of Juvenile Fishes from a Freshwater System (Paraná River, South America)

The concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn (TE) in four juvenile fishes (Acestrorhynchus pantaneiro, Salminus brasiliensis, Brycon orbignyanus, and Megaleporinus obtusidens) and associated sediment water from the Lower Paraná River were measured. For muscle, gills, and liver fishes, the TE accumulation in the muscle, gills, and liver was evaluated. The TE concentration was measured by quadrupolar inductively coupled plasma mass spectrometry (Q-ICP-MS). Cadmium (0.25 ± 0.07 μg L^-1), Cu (3.00 ± 1.44 μg L^-1), Fe (612 ± 69 μg L^-1), and Pb (1.92 ± 1.20 μg L^-1) in water and As (4.1-6.9 μg g^-1), Cr (20.1-31.4 μg g^-1), Cu (10.7-19.2 μg g^-1), Mn (351.3-482.2 μg g^-1), and Ni (24.5 ± 10.9 μg g^-1) in sediments exceeded the guide values for the conservation of aquatic life. In general, muscle of omnivorous species (B. orbignyanus and M. obtusidens) showed higher values of elements than those of carnivorous species (A. pantaneiro and S. brasiliensis). However, TE concentrations varied with fish species and organs. Independently of the examined species, the highest concentrations of Cr and Pb were in the muscle and gills, respectively. Cadmium, Cu, and Fe concentrations were higher in the liver than in gills and muscle in all four fish species. These results were consistent with the tissue selectivity index analyzed. For the four species, major essential elements showed the highest accumulation. However, the accumulation of toxic elements in omnivorous fish was higher than in carnivorous fish. The individual pollution load index indicated that sediment was very polluted with As and Pb, but based on the combined ecological indexes, low elemental sediment pollution in the Espinillo Lake was revealed.

Stabilization of heavy metals in biochar derived from plants in antimony mining area and its environmental implications

Heavy metals pollution in mining soils seriously threatens the ecological environment and human health worldwide. Phytoremediation is considered to be an ideal method to reduce the toxicity, mobility, and bioavailability of heavy metals in the soils. However, the disposal of plant-enriched heavy metals has become a thorny problem. To estimate the effect of pyrolysis on the stabilization of heavy metals in post-phytoremediation plant residues, different biochars were prepared from Conyza canadensis (CC), Gahnia tristis (GT), and Betula luminifera (BL) at different pyrolysis temperatures (300, 450, and 600 °C). Results indicated that pyrolysis was effective in the stabilization of heavy metals (Cr, Ni, As, Sb, Hg, and Pb) in plants and significantly (P < 0.05) decreased the bioavailability of most heavy metals. Among them, GT₆₀₀ prepared by pyrolysis of GT at 600 °C has the best stabilization effect on Sb, which increases the residual fraction by 7.32 times, up to 82.05%. The results of environmental risk assessment show that pyrolysis of biomass at high temperature (600 °C) can effectively mitigate the environmental impact of As, Sb, and Hg. Additionally, the reutilization potential of biochar produced by post-phytoremediation plant residues as adsorbents was investigated. The results of adsorption experiments revealed that all biochars have an excellent performance to adsorb Pb(II), and the maximum adsorption capacity is 139.16 mg g^-1 for CC₄₅₀. The adsorption mechanism could be attributed to complexation, electrostatic attraction, and cation exchange. This study demonstrates that pyrolysis is an effective and environment-friendly alternative method to stabilize heavy metals in plants, and their pyrolysis products can be reused for heavy metal adsorption.

Assessment of Land Use Pattern and Landscape Ecological Risk in the Chengdu-Chongqing Economic Circle, Southwestern China

The Chengdu-Chongqing Economic Circle (CCEC) is becoming the fourth growth pole in China after the Yangtze River Delta Economic Circle (YRDEC); Guangdong, Hong Kong, and Macao Economic Circle (GBAEC); Beijing, Tianjin, and Hebei Economic Circle (BTHEC). The land use and landscape ecological management of the CCEC is critical to its social and economic development. Using ArcGIS modeling and Fragstats processing methods, we divided the CCEC into 5 km × 5 km ecological risk areas and constructed a landscape ecological risk index evaluation model to calculate the spatial and temporal dynamic changes in the urban expansion and landscape ecological risk over the last 20 years. The results show that the land use was mainly cultivated land, which exhibited a decreasing trend and was mainly converted to construction land and forest land. The change in the construction land exhibited a continuous expansion trend with the dual core in Chengdu-Chongqing. The average risk of 10,155 risk communities was about 0.16. The expansion of human activities increased the landscape ecological risk of the construction land, and the risk of the edge of the cultivated land was higher than the internal risk value. The ecological risk index values of 16 cities in the study area ranged from 0.02 to 0.28. The resistance of the landscape pattern to external disturbance was stronger than that in other regions of China. The landscape ecological risk is controllable overall. However, the higher level of economic development in Chengdu, Chongqing, and other mature cities poses a greater landscape ecological risk. The results of this research provide an important reference for promoting the optimization and construction of the land space in the CCEC, building ecological shelters, and preventing ecological risk in the upper reaches of the Yangtze River.

Ecological Risk Assessment of Trace Metal in Pacific Sector of Arctic Ocean and Bering Strait Surface Sediments

The arctic region is a remote area with relatively few anthropogenic inputs, but there is increasing concern over toxic trace metal contamination in the Arctic Ocean. In this study, distribution characteristics of eight trace metals in the surface sediment of the Pacific Sector of the Arctic Ocean and Bering Strait are analyzed. The geochemical baseline value of each metal element is explored using the relative cumulative frequency curve method; the enrichment factor (EF), geo-accumulation index (I_geo) and potential ecological risk index (RI) are applied to assess the ecological risk level of the trace metals. According to the results, Cu, As and Hg had a little more content variation, and their contents in some areas were significantly higher than the previous reports. EF values show an obvious enrichment of element As, followed by Cr element with the moderate enrichment; the enrichment of the other six elements are not related to human activity. The I_geo value shows a moderately contaminated to heavily contaminated level of As and a moderately contaminated level of Cr. According to the potential ecological risk indexes in each site, most sites are at a low ecological risk level except five sites with RI/baseline values exceeding 150 which are at a moderate ecological risk level.

Ecological risks and controlling factors of trace elements in sediments of dam lakes in the Black Sea Region (Turkey)

The evaluation of trace elements (TEs) in sediments of dam lakes is crucial for maintaining ecosystem health. Therefore, it is very important to determine their concentrations, pollution status, sources, controlling factors and ecological risks in these ecosystems. Here, for the first time, we analyzed 14 TEs (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg and Pb) and sediment properties (organic matter (OM) and pH) in sediments from four dam lakes (Erfelek, Derbent, Suat Uğurlu and Saraydüzü) in the Black Sea Region of Turkey, which are used for different purposes and located on the different rivers or streams with different pollution levels. The results indicated that Al, V, Mn, Fe, Cu, Zn, As, Pb and Sb concentrations were lower in the Erfelek Dam Lake which has been used for drinking water supply, indicating that it is more protected than other dam lakes. However, Al, V, Mn, Fe, Co, Cu and Sb concentrations were higher in the Suat Uğurlu Dam Lake on the Yeşilırmak River which is moderately polluted. According to sediment contamination indices, there was low contamination in the sediments of all dam lakes. Similarly, the assessment of ecological risk posed by TEs indicated low eclogical risk in the dam lakes. Sediment OM and pH were found to be important control factors affecting the distribution of TEs in the dam lakes sediments. Correlation and factor analyses suggested that all TEs in the sediments of dam lakes mainly originated from geogenic sources.

Assessment of Soil Quality Status and the Ecological Risk in the Baia Mare, Romania Area

Industrial activities in the Baia Mare, Romania area have generated strong pollution, and the impact on soil quality in the neighboring areas of the city remains unclear. The aim of the research is to investigate samples of soil from Baia Mare in order to determine the quality of the soil and also the ecological risk of the soil. This study presents among the first studies using the ecological risk assessment methodology on the soil from the Baia Mare area and aims to serve as scientific support for future studies and research. Evaluation of the soil quality state was performed by determining the physical-chemical characteristics of the soil (pH, texture, structure, and concentration of metals). Evaluation of the anthropic activity from the studied areas was conducted by determining the pollution indices: Cf; Cd, PLI, Er, and PERI. The results of this study indicate that the surface soils have very high concentrations of metals (Cd: 3.5–14.4 mg kg−1; Cu: 9.4–361.5 mg kg−1; Pb: 29.7–1973 mg kg−1), with exceedances of the limit values established in the Romanian legislation. Results regarding the degree of contamination, the PLI pollution load index (1.3–14.9), and the PERI potential ecological risk index (733.9–4686) indicate that soils in the studied area have a very high degree of pollution.

Sustainable and efficient stabilization/solidification of Pb, Cr, and Cd in lead-zinc tailings by using highly reactive pozzolanic solid waste

Lead-zinc tailings (LZTs) are industrial by-products containing a large number of heavy metals that seriously harm the ecological environment and human health. This study was performed to propose a sustainable and efficient method for immobilizing Pb, Cr, and Cd in LZTs by using solid waste. To better assess the immobilization performance and mechanism, the leaching toxicity, fraction distribution, unconfined compressive strength, environmental risk assessment, and hydration products were explored. The LZTs were mixed and molded with different constituents of ground granulated blast furnace slag (GGBFS) and rice husk ashes (RHAs) at different curing temperatures. Results suggest that ≥99% of the Pb, Cr, and Cd were immobilized mainly in the form of residual fractions in the LZTs. The amounts of Pb, Cr, and Cd in the bioavailable fractions notably decreased by approximately 99.83%, 99.58%, and 97.05%, respectively. After stabilization/solidification (S/S) disposal, Pb, Cr, and Cd showed low to even no risk. The RHAs were effective to stabilize Pb, and GGBFS was effective to stabilize Cr. However, both materials showed almost equal effects to Cd. Ettringite, C-S-H gel, and portlandite were the main hydration products to immobilize Pb, Cr, and Cd, and these hydration products provided a source of strength. Honey-comb or reticular network C-S-H gel possessed higher specific surface area, higher pore volume, and bigger pore size than the other materials. The proposed method could explain the sustainability and efficiency of the S/S of Pb, Cr, and Cd in LZTs by using RHAs. This study opens up new perspectives for disposing heavy metal by using accessible agricultural solid waste (i.e., RHAs) in rural areas, and the solidified block shows certain economic benefits.

Trend analysis of anthropogenic activities affecting trace metals deposition in core sediments from the coastal and four rivers estuary of Sarawak, Malaysia

This study reports the concentrations of trace metals in core sediments profile from the coastal and four rivers estuary in the Kuching Division of Sarawak, Malaysia, and the controlling mechanisms influencing their availability in sediments of the studied area. The bonding of trace metals with non-mobile fractions was confirmed with the sequential extraction. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of the trace metals. Granulometric analyses were performed using normalized sieve apertures to determine the textural characteristics of the sediments. Enrichment factor was used to evaluate the level of metal enrichment. Heavy metals concentrations in sediment samples varied in the range: Pb (8.9-188.9 mg/kg d.w.), Zn (19.4-431.8 mg/kg d.w.), Cd (0.014-0.061 mg/kg d.w.), Ni (6.6-33.4 mg/kg d.w.), Mn (2.4-16.8 mg/kg d.w.), Cu (9.4-133.3 mg/kg d.w.), Ba (1.3-9.9 mg/kg d.w.), As (0.4-7.9 mg/kg d.w.), Co (0.9-5.1 mg/kg d.w.), Cr (1.4-7.8 mg/kg d.w.), Mg (68.8-499.3 mg/kg d.w.), Ca (11.3-64.9 mg/kg d.w.), Al (24.7-141.7 mg/kg d.w.), Na (8.8-29.4 mg/kg d.w.), and Fe (12,011-35,124.6 mg/kg d.w.). The estimated results of the enrichment factor suggested enrichments of Pb, Zn, and Cu in all the core sediment samples and depths at all sites. The other trace metals showed no enrichments in almost all the sampled stations. Continuous accumulation of Pb, Zn, and Cu metals over a period can be detrimental to living organisms and the ecology. The results obtained from the statistical analyses suggested that the deposition of trace metals in the studied sites is due to anthropogenic inputs from the adjacent land-based sources.

Sediment contamination by trace elements and the associated ecological and health risk assessment: A case study from a large reservoir (Turkey)

Although Keban Reservoir (KR) is Turkey's the second largest man-made reservoir, limited data are available on the contents of trace elements (TEs) in sediments of the KR. The concentrations of 23 less- and commonly-monitored TEs in the sediments from 49 sites in the reservoir were measured to assess health risks, contamination levels and ecological risks of TEs. Concerning median Enrichment Factor values of TEs, chromium (Cr), strontium (Sr) and nickel (Ni) showed moderate enrichment, while other TEs showed minimal enrichment. Pollution Load Index values ranged from 0.33 to 0.63, indicating no a multi-element contamination case in the study area. Low ecological risk was found at 47 sites, while moderate ecological risk was recorded at two sites. The PEC (probable effect concentration) values were exceeded for Ni and Cr. Although wastewater from leather processing factory partly contributed to Cr enrichment at site 2, all TEs mainly originated from lithogenic sources. Median hazard quotient (HQ) values of zirconium (Zr) and lanthanum (La) for children from sediment ingestion were above the risk threshold of unity (HQ = 4.81 and 1.39) and contributed 62.9% and 18.2% of the total health risk. Such high HQ values of Zr and La have never been reported in the literature. Hazard index values for children exceeded those for adults, indicating that children are more vulnerable to health risks than adults. Carcinogenic risk values of arsenic (As) were within the acceptable limits. Our findings indicated that in a multi-element sediment study, some less-monitored elements such as Zr and La may have an important role in health risk assessment even if they are found in the sediment at low concentrations. Therefore, this study can be a model for future similar studies evaluating the health risks of multi-elements in sediments.

Heavy metals in a typical city-river-reservoir system of East China: Multi-phase distribution, microbial response and ecological risk

The rapid construction of artificial reservoirs in metropolises has promoted the emergence of city-river-reservoir systems worldwide. This study investigated the environmental behaviors and risks of heavy metals in the aquatic environment of a typical system composed of main watersheds in Suzhou and Jinze Reservoir in Shanghai. Results shown that Mn, Zn and Cu were the dominant metals detected in multiple phases. Cd, Mn and Zn were mainly presented in exchangeable fraction and exhibited high bioavailability. Great proportion and high mobility of metals were found in suspended particulate matter (SPM), suggesting that SPM can greatly affect metal multi-phase distribution process. Spatially, city system (CiS) exhibited more serious metal pollution and higher ecological risk than river system (RiS) and reservoir system (ReS) owing to the diverse emission sources. CiS and ReS were regarded as critical pollution source and sink, respectively, while RiS was a vital transportation aisle. Microbial community in sediments exhibited evident spatial variation and obviously modified by exchangeable metals and nutrients. In particular, Bacteroidetes and Firmicutes presented significant positive correlations with most exchangeable metals. Risk assessment implied that As, Sb and Ni in water may pose potential carcinogenic risk to human health. Nevertheless, ReS was in a fairly safe state. Hg was the main risk contributor in SPM, while Cu, Zn, Ni and Sb showed moderate risk in sediments. Overall, Hg, Sb and CiS were screened out as priority metals and system, respectively. More attention should be paid to these priority issues to promote the sustainable development of the watershed.

Toxic metal pollution and ecological risk assessment in water and sediment at ship breaking sites in the Bay of Bengal Coast, Bangladesh

Quantification of four toxic metals (As, Cr, Cd, and Pb) in water and sediments at the Sitakunda ship breaking area in Bangladesh was studied. Along with this, sediment quality and ecological risk were evaluated for the metal intrusion to the study area. A total sample number of 120 (water; n = 60 and sediment; n = 60) were analyzed for both winter and summer seasons using atomic absorption spectrophotometer (AAS). The trace metal concentration in both water and sediment showed decreasing trend as follows; Cr (mean-W: 0.118 mg/L; mean-S:121.87 mg/kg) > Pb (mean-W: 0.064 mg/L; mean-S: 65.31 mg/kg) > As (mean-W: 0.03 mg/L; mean-S: 32.53 mg/kg) > Cd (mean-W: 0.004 mg/L; mean-S: 4.81 mg/kg). However, in both segments, the concentrations of the toxic metals exceeded the recommended acceptable limits. As and Cd showed significant variation (water and sediment) between the seasons, while Pb and Cr had no seasonal impact. Metal pollution index (MPI) and contamination factor (CF) was evaluated and revealed that the study area exhibited the critical score of water quality (MPI > 100). The cumulative effect of the metal concentrations was high (CI > 3). The assessed mean geoaccumulaiton index (I_geo) revealed that the study area was moderate to strongly polluted except for Cr. According to the contamination factor (CF), the sediment samples were moderate to highly contaminated by Cd, Pb, and As. Moreover, the explored range of pollution load index (PLI) in all sampling sites in the ship breaking region was from 1.75 to 3.10, suggesting that the sediment in the study area was highly polluted by heavy metals (PLI > 1). The risk index and the potential ecological risk index (PERI) suggested that the study area was at high risk due to metals pollution. Therefore, it is obligatory to maintain some crucial efforts for the betterment of the surrounding environment near the investigated sites.

Trace metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in the surface sediments from Sanya River, China: Distribution, sources and ecological risk

The urban inland river ecosystems are now facing comprehensive pollution and governance pressures. Up to now, few works related to the multiple pollution assessment of trace metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) for the urban inland river sediments have been reported in China. Our study investigated the spatial distribution, ecological risk and potential sources of trace metals, PAHs and PCBs in surface sediment collected from 20 sampling sites of Sanya River, Hainan Province, China. The pollution status and potential ecological risk of trace metals were evaluated using the contamination indexes including geoaccumulation index (I_geo), individual potential ecological risk (E_rⁱ), potential ecological risk index (RI) and pollution load index (PLI). Considering the carcinogenicity and toxicity of PAHs and PCBs to human health and the ecological environment, we also analyzed the distributions, sources and adverse biological effects of PAHs and PCBs according to the sediment quality guidelines (SQGs), principal component analysis (PCA) and other source analysis. This study revealed that the surface sediments in Sanya River were extremely slight pollution and showed a very low ecological risk according to I_geo, E_rⁱ, PLI and RI results for trace metals. Besides, PAHs and PCBs pollution detected may not pose considerable adverse biological effect to ecological environment in a foreseeable period on the basis of comprehensive research results. The overall surface sediments quality of the Sanya River not seem to pose a serious pollution and ecological risk based on the evaluation results of multiple pollution factors. The study provided detailed information on the multiple pollution status and location of surface sediments, one of the key environmental indicators of international tourism cities, in the Sanya River, which would be useful for the water quality improvement of Sanya River and the environmental remediation of the other coastal ecosystems from different regions.

Spatial-Temporal Variations, Ecological Risk Assessment, and Source Identification of Heavy Metals in the Sediments of a Shallow Eutrophic Lake, China

The contamination of heavy metals (Pb, Cr, Hg, Cd, Ni, Cu, Zn, As, and Sb) in the sediments were investigated in Lake Yangcheng, a eutrophic lake in China. Results showed that the average concentrations of each metal in the surface sediments generally exceeded their corresponding background values. Higher values were observed in deeper zones, supporting the retention and accumulation of heavy metals in the core sediments. The spatial distributions of metal averages, pollution load index (PLI), and combined ecological risk index (RI) revealed that ecological risks were highest in the west lake, followed by middle lake, and were lowest in the east section. For the temporal variations of metal contents, the highest concentration was usually observed in the winter. However, the seasonal dynamics of Hg showed a different pattern with higher values in the autumn and lower values in the winter. According to contamination factor (CF), the Hg and Sb contaminations were considerable, while the other metals were moderate contamination. In terms of geoaccumulation index (I_geo) values, sediments were moderately–heavily polluted by Sb and moderately polluted by Hg, Cd, and Ni. Meanwhile, Hg exhibited a considerable health risk, while Cd and Sb were moderate risks, based on single ecological risk index (Er) values. Significant positive correlations among heavy metals and principal component analysis (PCA) indicated that anthropogenic activities were major sources. The source of Sb might be different from other metals, with industrial discharge as the main loading. This study highlighted the urgency of taking measures to prevent Hg, Sb, and Cd pollutions in Lake Yangcheng, especially the west region of this lake.

Quantitative source identification and environmental assessment of trace elements in the water and sediment of rivers flowing into Laizhou Bay, Bohai Sea

The concentrations, sources, and ecological risks of nine trace elements in nine rivers flowing into Laizhou Bay were investigated. The dissolved element concentrations were 1.85-74.4, 0.01-0.47, 0.15-3.46, 1.54-19.7, 2.92-45.1, 1.72-11.5, 1.02-8.35, 0.10-1.02, and 21.4-185 μg/L for As, Cd, Co, Cr, Cu, Ni, Sc, Pb, and Zn, respectively. Zinc was the most abundant element in the sediments, with an average concentration of 106 mg/kg, followed by Cr (64.5 mg/kg), Cu (25.5 mg/kg), Pb (24.3 mg/kg), Ni (23.4 mg/kg), Co (10.9 mg/kg), Sc (8.14 mg/kg), As (6.75 mg/kg), and Cd (0.16 mg/kg). Elements including Co, Cr, Ni, and Sc were mainly from natural sources and As, Cd, Cu, Pb, and Zn were largely influenced by anthropogenic activities such as agricultural practice, industrial production, river transportation, and urbanization. Overall, the rivers flowing into Laizhou Bay experienced slight pollution and ecological risk. However, the severe element contamination in Jie River deserves continuous attention.

Spatial-temporal evolution of agricultural ecological risks in China in recent 40 years

Excessive use of agricultural chemicals and unreasonable utilization of agricultural wastes have led to severe agricultural non-point source pollution (ANPSP) problems in China. Based on the agricultural pollution loads and pollution control strength, the ecological risk index (ERI) was constructed and was used to explore the spatial-temporal pattern of agricultural ecological risks in China during 1978-2017. The findings indicated that Chinese agricultural ERI was gradually increased from 0.031 to 0.348 in 1978-2017, which has the same phased change characteristics as the succession of agricultural policies. At present, the ecological risk grade of ANPSP was present in the stair-step distribution characteristics of "high in the east and south and low in the west and north" as a whole. Southern China, as the main producing area of aquatic products, had the higher ecological risks. Northeastern China, the Huang-Huai-Hai Area, and the middle and lower reaches of the Yangtze River, as the grain-producing bases, had moderate ecological risks, but Southwestern China and Northwestern China with the poor agricultural production conditions had the lower ecological risks. It evidently showed that the ecological risk problems faced by the high-quality development of Chinese agricultural industrialization are increasingly severe.