Ecological Risk Assessment Of Heavy Metals Research Articles

Content, Sources, and Ecological Risk Assessment of Heavy Metals in Soil of Typical Karst County

Soil heavy metals in karst areas have obvious high background value characteristics. Conducting county-level soil heavy metal ecological risk assessment and identifying heavy metal sources in karst areas are of great significance for soil pollution control and land resource management. Taking Pingguo City, a typical karst county in Guangxi Province, as the study object, 3 151 surface and deep soil samples were collected using the grid method and combined to form 785 analytical samples. The contents of eight heavy metal elements, including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, were determined. The content characteristics and sources of heavy metals were analyzed using statistical analysis, interpolation analysis, factor analysis, and the absolute principal component-multiple linear regression model （APCS-MLR）. Using the content of heavy metal elements in deep soil （150-200 cm） as background values, the ecological risk assessment of heavy metals in surface soil （0-20 cm） in the study area was conducted using the geo-accumulation index （Igeo） and potential ecological risk index （RI） methods. The results showed that the average content of heavy metal elements in the deep soil of the study area was significantly higher than the background value of the C layer soil in Guangxi Province, and the average content of heavy metal elements in the surface soil was significantly higher than the background value of the A layer soil in Guangxi Province. The spatial distribution of soil heavy metal element content generally showed the characteristics of high in karst areas and low in non-karst areas. The main sources of As, Cr, Ni, Pb, and Zn were soil parent materials, with contribution rates of 74.36%, 84.59%, 93.69%, 79.67%, and 78.17%, respectively. The main sources of Cd were soil parent material sources and unknown sources, with contribution rates of 37.33% and 31.05%, respectively. The main sources of Cu were soil parent materials and unknown sources, with contribution rates of 59.07% and 40.23%, respectively. The main sources of Hg were tectonic activity and mineralization, as well as unknown sources, with contribution rates of 52.49% and 30.65%, respectively. The geo-accumulation index （Igeo） showed that the surface soil was mainly polluted by Cd, with mild or above pollution accounting for 47.78%. The potential ecological risk index （RI） showed that the proportion of surface soil heavy metal comprehensive potential ecological hazards with mild, moderate, strong, and very strong levels was 80.78%, 14.97%, 2.51%, and 1.64%, respectively.

Spatial Distribution, Source Identification, and Potential Ecological Risk Assessment of Heavy Metal in Surface Sediments from River-Reservoir System in the Feiyun River Basin, China.

To investigate the pollution characteristics of the surface sediments of the river-reservoir system in the Feiyun River basin, a sediment heavy metal survey was conducted for the first time in the Feiyun River basin. Surface sediments from 21 sampling sites in the Feiyun River basin were collected, and the concentrations and spatial distribution characteristics of 15 heavy metals (Cr, Ni, Cu, Zn, As, Cd, Pb, Mn, V, Co, Mo, Sb, W, Fe, and Se) were analyzed. Three heavy metal ecological risk assessment methods were used to evaluate the potential risks of heavy metals in sediments, and the sources of major heavy metals were traced by correlation analysis and principal component analysis. The results show that (1) the average concentration of heavy metals (As) (212.64 mg/kg) and (Sb) (4.89 mg/kg) in Feiyun River Basin is 33.3 and 6.89 times the background value of Zhejiang Province; the overall spatial distribution of heavy metals is: the mainstream of Feiyun River > Zhaoshandu Reservoir > Shanxi Reservoir, thereby, the pollution is relatively significant; (2) by processing the geo-accumulation index and enrichment index methods, As and Sb are classified as 'severely polluted', 'moderately severely polluted' and 'severely polluted', 'very severe polluted' respectively; (3) the potential ecological index evaluates the surface sediments in the Feiyun River Basin as a very high risk level, the main environmental risk factors are As, Sb, Cd and Mo; (4) the principal component analysis results show that the heavy metals in the sediments of the Feiyun River Basin may be mainly affected by human activities such as sewage from domestic and agricultural activities, mining and smelting, and the others are affected by natural factors.

Heavy metals pollution characteristics and risk assessment in sediments and waters: The case of Tianjin, China

Potential health and ecological risks due to heavy metal pollution in surface waters and sediments were evaluated based on a health risk assessment model and a potential ecological risk index method. Combined with the reclamation progress of Tianjin Nangang Industrial Zone, in China, a survey was carried out in the area dealing with heavy metals concentrations in surface waters and sediments, covering from 2008 to 2018. Specifically, concentrations were determined for As, Cd, Hg, Cu, Pb, and Zn. The results show that As、Cd、Hg、Cu 、Pb、Zn average concentrations in surface water were 0.99 μg/L∼1.27 μg/L, 0.13 μg/L∼0.63 μg/L, 0.03 μg/L∼0.13 μg/L, 1.5 μg/L∼4.65 μg/L, 1.25 μg/L∼4.7 μg/L, 13.5 μg/L∼20.99 μg/L and which average concentrations in sediment were 5.12 mg/kg∼12.34 mg/kg, 0.12 mg/kg∼0.18 mg/kg, 0.04 mg/kg ∼0.087 mg/kg, 13.45 mg/kg∼31.92 mg/kg, 13.2 mg/kg ∼21.26 mg/kg, 21.58 mg/kg ∼77.21 mg/kg, respectively. The background values of the Hailuan River basin near the study area were taken as the reference and compared with the national sediment quality standards a tell us the quality of the sediments in Tianjin Nangang coastal area being good. As regards the characteristics of pollution, heavy metals showed a high concentration in 2008 and then decreased significantly, which related to the dredging of large amounts of contaminated surface sediment during port construction. According to the phase equilibrium partition coefficient (Kp) and temporal and spatial distribution characteristics of heavy metals, sediments can be seen as an obvious sink for lead, with this element being mainly affected by exogenous input in coastal seawater. Zn, As, Cd, and Hg contents in surface water were greatly affected by the endogenous release from sediments. The results of the environmental risk assessment showed that the main environmental health risk of Tianjin coastal waters was carcinogenic, and specifically due to As. The potential heavy metals ecological risk assessment results of surface sediments were mild for the affected areas.

HEAVY METALS AND HYDROCARBONS IN SEDIMENT AND CRAB (CARDISOMA ARMATUM) AND ECOLOGICAL RISK ASSESSMENT OF AMADI CREEK, PORT HARCOURT

Food security is hinged on quality and integrity of the surrounding environment. Food quality and security of coastline communities are tied to the constituents of benthic organisms in the area. This study assessed the heavy metals and hydrocarbons status of sediment and crab (Cardisoma armatum) in Amadi Creek in Port Harcourt. Sediment and crab samples were collected from five stations along a 10 km transect for four months. The heavy metals results for sediment showed the following: Zn (18.624 ± 1.254), Pb (0.791 ± 0.072), Cd (0.031 ± 0.012), Cr (3.323 ± 1.079), Ni (1.848 ± 1.329) and V (0.067 ± 0.102 mg/Kg). The heavy metals ranges in the crab were Zn (20.838 ± 7.803), Pb (0.000 ± 0.000) Cd (0.004 ± 0.014), Cr (0.500 ± 0.239), Ni (1.181 ± 0.562) and V (0.055 ± 0.112 mg/Kg). Hydrocarbon results for sediment were TPH (10.020 ± 11.255), PAH (1.377 ± 1.587 mg/Kg), while the crab had ranges of TPH (1.732 ± 2.235) and PAH (0.003 ± 0.007 mg/Kg). The results were within regulatory permissible limits of EGASPIN and WHO. ANOVA at p>0.05 indicated no significant spatial difference between the heavy metals and hydrocarbon concentrations in the sediments and crab at the various stations along the transect. Sediment heavy metal Ecological Risk Assessment revealed that contamination degree and pollution load index were < 1 (indicating no pollution); geo-accumulation index was grade 0 (unpolluted), individual potential risks and potential ecological risk index were < 40 and < 150 respectively (indicating low ecological risk). Sediment to biota transfer factor indicated that Zn was the only heavy metal biomagnified in the crab. Human health risk assessment of the heavy metals in the crab was less than 1 indicating no obvious health risk for cancer over a lifetime of exposure.

Evaluation of ecological risk of heavy metals in watershed soils in the Daxia River Basin

Watershed ecological risk is affected by the environment, climate, and human activity. In this study, the Daxia River Basin in northwestern China was regarded as the research area. The remote heavy metal ecological risk assessment model of the basin was constructed using remote sensing data, normalized difference vegetation index (NDVI), and environmental factors. The results show that different areas of the basin have different ecological risk levels depending on the geographical location and the level of human activity. A multivariate linear relationship exists between the NDVI and heavy metal content, precipitation, and temperature, and a correlation coefficient (r) of 0.866 was derived at a significance level of P < 0.01. There was a nonlinear relationship between the average heavy metal content and the Health Risk Index. The model correlation coefficient equals 0.893 at P < 0.01. The results of the study further demonstrate that risk assessment of the basin can be carried out using remote sensing information and environmental meteorological factors. It also reveals that establishing vegetation helps inhibit the migration of heavy metals in the soil.

Contamination and ecological risk assessment of the Red Sea coastal sediments, southwest Saudi Arabia

The level of heavy metals (HMs) in coastal sediments has attracted the environmental researchers due to their persistence, abundance, biomagnification and toxicity. The present study was conducted to assess the contamination and ecological risk assessment of HMs in Jazan coastal sediments, Red Sea, Saudi Arabia utilizing pollution indices and multivariate statistical analyses. A total of 32 surface samples were collected for Cu, Sb, Zn, Cr, Cd, Pb, Fe, Co, Ni, Al, and total organic matter analysis using an atomic absorption spectrophotometer. The results indicate the following descending order of metal concentrations: Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Cd > Sb. Average level of Cd is significantly higher than those from many neighboring and worldwide coastal sediments; and recorded very severe enrichment, severe contamination and very high risk in the investigated sediments. The pollution indices and statistical analyses revealed that proportion of Zn, Fe, Ni, Cr, Al, Cu, Sb and Pb were formed from lithogenic sources of weathering Quaternary units and atmospheric deposition. Most of the Cd, Sb, and Pb levels were derived from anthropogenic sources of industrial, agricultural, and fishing activities. The higher contribution of organic matter may be attributed to the mangrove roots and organic fertilizers; and played a key role in adsorbing, transferring and accumulating of elements.

Heavy Metals Pollution Characteristics and Ecological Risk Assessment of the Sediments of Anrongjing River in Taizhou City

In order to study the heavy metals pollution in the river channel of the city, this paper based on the results of the sediments detections of Anrongjing River in Taizhou, using the single pollution index method, the potential ecological risk index method, the cluster analysis method and other methods to evaluate the content, the degree of pollution, the distribution, ecological risk assessment, etc. of heavy metals. The results show that Cu, Zn, Pb and Cd in the sediments are seriously polluted. Viewed from the plane, the main pollution areas are the upstream, the two tributaries and the tributaries and main river crossings. Viewed from the vertical, the heavy metals pollution roughly decreases with increasing sediments depth. The results of heavy metals ecological risk assessment show that the potential ecological hazards of Cu and Cd are serious, the pollution of Cd and Cu in the source, the two tributaries and tributaries and main river crossings are the most serious.