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 (Igeo) 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.

Source Identification, Ecological Risk and Spatial Analysis of Heavy Metals Contamination in Agricultural Soils of Tanjaro Area, Kurdistan Region, Iraq

The current work accomplished a comprehensive evaluation of heavy metals pollution in soil of agricultural areas from Tanjaro sub-district, Sulaimaniyah province, Kurdistan Region, NE Iraq. Ninety soil samples were collected from thirty different locations. Concentrations of 16 heavy metals were measured by inductively coupled plasma optical emission spectrometry ICP-OES. The pollution index (PI), potential ecological risk index (Er), enrichment factor (EF), and ecological risk index (RI) were used to assess the pollution in soil samples. High levels of Li and Ni, and moderate Ba, Cd, Hg, and Pb according to the results of concentration analysis, pollution index (PI), and potential ecological risk (ERI). High levels of Cd and Hg according to the results of Er. Agglomerative hierarchical clustering (AHC) and principal component analysis (PCA) suggested that heavy metals were generated from different natural and anthropogenic sources like natural weathering, fertilizer application, and transportation. Origins of Hg, Cd, Ni, and Pb are probably from activities like overuse of pesticides and fertilizers, whereas Pb could be exhausted from vehicle exhausts as well. Furthermore, spatial distributions revealed nonpoint source pollution for the studied heavy metals. The obtained results help in the remediation techniques of contaminated soils such as dilution with decontaminated soil or extraction or separation of heavy metals.

Distributions, Compositions, and Ecological Risk Assessment of Typical Pollutants in Surface Sediment of Xihe River, China

Distributions and compositions of six phthalic acid esters (PAEs), eight phenol compounds and seven heavy metals in riverbed sediments of the Xihe River in Shenyang, China. The ecological risks of these typical pollutants were investigated and evaluated based on the risk quotient (RQ) and potential ecological risk index (PERI) methods. The concentrations of total ∑6PAEs, ∑8phenols and ∑7heavy metals in sediments varied from 92.83 to 293.66 μg/g dw, 8.87 to 83.73 μg/g dw and 0.46 to 419μg/g dw. The main pollutants in Xihe River sediments are DEHP, DIBP, phenol, P-methylphenol and Cd. More than half target PAEs and phenol compounds in sediment of the Xihe River exhibited medium or high ecological risk. Cd poses a very high ecological risk to the Xihe River Basin. It is imperative to take some effective measures to reduce the pollution of those contaminants.

Assessment of Arsenic and Copper Pollution of the Benya Lagoon, Ghana By Neutron Activation Analysis

Heavy metal concentrations in some water bodies and the soil beneath these waters. These would have detrimental consequences on these water users and consumers of the fish in that water. Instrumental Neutron Activation Analysis technique using the Ghana Research Reactor-1 was employed to find out the concentrations of two heavy metals, Arsenic (As) and Copper (Cu) in the sediments, fishes, and water collected from the Benya Lagoon in the KEEA, Ghana. Cumulatively, Copper was found to be greater in concentration than Arsenic concerning the three parts of the ecology under study. On the other hand, Arsenic was more concentrated in the sediments than Copper, and Copper was more concentrated in the water and fish than Arsenic. Cumulatively, the level of contamination of Arsenic and Copper decreased in the order fish > sediment > water. Though Arsenic and Copper were found in elevated amounts in both water and fish which rendered the Lagoon water unsuitable for human use and the fish from the Lagoon unsafe for consumption, their concentrations in the sediment were found to have a low ecological risk index on the environment.

A Comprehensive Exploration on Pollution Characteristics and Ecological Risks of Heavy Metals in Surface Paddy Soils around a Large Copper Smelter, Southeast China

To assess heavy metal pollution and ecological risk, a total of 28 surface paddy soil samples were collected and analyzed around a famous copper smelter in Guixi, China. The results showed that all sites were heavily contaminated by both Cu and Cd, compared with soil background values, whose average concentrations exceeded the standard by 5.7 and 12.3 times, respectively, posing a slight ecological risk related to Cu (potential ecological risk index <40) and an extremely serious ecological risk related to Cd (potential ecological risk index >320). The risks were also demonstrated through the speciation analyses of Cu (CaCl2-Cu 2.63%, acid-soluble Cu 8.67%, and residual Cu 74.17%, on average) and Cd (CaCl2-Cd 47.30%, acid-soluble Cd 45.02%, and residual Cd 28.87%, on average) in the surface paddy soil, including the use of a CaCl2 extraction procedure and the BCR (Community Bureau of Reference) sequential extraction scheme. Several soil properties (residual carbon, cation exchange capacity, and soil texture) were significantly correlated with soil Cd but made a small contribution to their variability with a poor linear fit because of external Cd input to the soil, while soil total potassium largely influenced the soil Cu species except for residual Cu. Therefore, an effective Cu pollution regulation strategy through soil potassium control is suggested for this smelter soil.

Analysis of Soil Heavy Metal Pollution and Investigation of Dominant Plants in Abandon Gold Ming Area

In recent years, environmental pollution and ecological destruction in mining area has seriously affected the health and survival of surrounding people. To explore the degree of heavy metal pollution in soil of mining areas and phytoremediation strategies, we chose soil and dominant plants in an abandoned gold mining area as the research object. In this study, Arsenic (As) content in soil and plants was measured. The As pollution degree in local areas was evaluated by using geo-accumulation index and potential ecological risk index. And, As content in plants was analyzed by using enrichment coefficient method. The results show that 1) The pulp deposition area has the most serious As pollution of soil and the largest potential ecological risk index. 2) The composition of the plant community in the study area is dominated by herbaceous plants, among which gramineous, composites and legumes are the dominant plant types in the vegetation community restoration in the mining area. 3) The geoaccumulation index is significantly negatively correlated with species diversity index, Shannon-wiener diversity index and Pielou species evenness index. 4) The As content in dominant plants ranges from 0.11 to 15.92 mg/kg. The plants with strong As enrichment ability are Erigeron annuus (L.) Pers., Periploca sepium Bunge, and Setaria viridis (L.) Beauv., which can be considered as As-tolerant plants. This study can provide a basis and reference for plant management of As pollution in local soil.

Ecological risk and enrichment of potentially toxic elements in the soil and eroded sediment in an organic vineyard (Tokaj Nagy Hill, Hungary)

Potentially toxic elements (PTEs), such as Cu, Zn, Pb, Ni, Cr, and Co, can accumulate in vineyard soils due to repeated uses of inorganic pesticides and chemical or organic fertilizers. In sloping vineyards, PTEs can also be moved by soil erosion resulting in their accumulation in low-energy zones within the landscape, adversely affecting the soil environment. Our study evaluated the ecological risk related to the pseudo-total and bioavailable PTE contents (Zn, Pb, Co, Ni, Cr, and Cu) in the soil and eroded sediment samples from an organic vineyard in Tokaj (NE Hungary). The contamination status and the ecological risk of target PTEs were assessed by calculating the contamination factor, the pollution load index, the ecological risk factor, and the ecological risk index. The median pollution load indices of 1.15, 1.81, and 1.10 for the topsoil, the sediments, and the subsoil, respectively, demonstrate a moderate multi-element contamination case in the organic vineyard. Target PTEs tented to show increased concentrations in eroded sediments with the highest enrichment ratio (3.36) observed for Cu (Cu in the sediment/Cu in the topsoil), revealing a preferential movement of Cu-rich soil particles by overland flow. Moreover, PTEs were present in the sediments in more bioavailable forms (except Ni, Cr), assessed by an extraction procedure with EDTA. The ecological risk index (< 90) based on the studied PTEs showed an overall low ecological risk in the vineyard. Copper was the predominant factor of the ecological risk. Moreover, the highest ecological risk factor (24.6) observed for the bioavailable Cu content in an eroded sediment sample (representing 82% of the total ecological risk) shows that Cu accumulation in sloping vineyards is an ecological risk, particularly in the sedimentation zones. The high proportions of bioavailable Cu in the vineyard’s soil represent an increasing ecological risk over time, related to repeated treatments of vine plants with Cu-based pesticides.

Distribution and Ecologica Risk of Sediment Heavy Metals in the Water-Level-Fluctuation Zone of the Shawan River Section of Yelang Lake

With the aim of revealing the potential ecological risk and distribution characteristics of heavy metals on the surface sediment at the Shawan River section of Yelang Lake, the following three analyses were first performed: (1) analysis of grain-size composition on sediment samples collected at seven different sites in the water-level-fluctuation zone (WLFZ); (2) analysis of bulk sediment content of six heavy metals, namely, Cd, Cr, Pb, Mn, Zn, and Cu; and (3) the correlation analysis of grain-size composition and heavy metal content in the sediment. Afterwards, the approach of Hakanson potential ecological risk index was employed to analyze the risk of heavy metal pollution in sediments of seven WLFZ plots. The outcomes indicate that (1) the mean sediment grain size at each sampling site was generally >0.063 mm, with gravel grains (>1 mm) and sand grains (0.22–1 mm) accounting for the largest proportions; (2) the site-averaged mean sediment content of each of the six heavy metals was significantly higher than their respective geochemical background contents in the sediment of Guizhou Province, and the grain-size dependence of the bulk sediment content of heavy metals was not significant; (3) the distribution of Cr was relatively independent of other metals, which was in contrast to notable positive correlations observed between other metals; and (4) in accordance with the approach of Hakanson potential ecological risk index, for these heavy metals, their potential ecological risk reduced by the order of Zn < Cr < Cu < Pb < Cd, with Cd having a mean potential risk index (Ei) of 566.13, suggestive of a very high level of potential ecological risk, Zn, Cr, and Cu having a mild potential ecological risk, and Pb having moderate potential ecological risk. Cd largely contributes to the comprehensive ecological risk index RI is the largest, thereby having important environmental implications.

Potential Ecological Risks of Heavy Metals in Agricultural Soil Alongside Highways and Their Relationship with Landscape

The agricultural soil alongside highways has experienced multiple potential ecological risks from human activities. In this study, 100 soil samples near the highways were collected in Lishui District, Nanjing City. Using the single-factor pollution index, the Nemerow comprehensive pollution index, and the potential ecological risk index, the study investigated the heavy metal contents and distribution in roadside agricultural soil. PCA and a multiple regression model were applied to quantitatively analyze the spatial relationships between sampling soil heavy metal accumulation and the surrounding man-made landscape. The mean contents of Cu and Pb exceeded the background, while Cd, Cr, and Zn were lower than that. The potential ecological risk index exhibited a very low ecological hazard and only Cr in soils rarely showed moderate risk. Furthermore, quantitative analysis for the sources of contamination revealed that agricultural practices were the dominant contributors to the heavy metals, including Cd, Cu, and Zn, while road and heavy industrial practices contributed to Cr and Pb. The study provides sources of heavy metal pollution from human activities in roadside agricultural land and serves as a reference for ecological restoration.

Pollution, Ecological Risk and Source Identification of Heavy Metals in Sediments from the Huafei River in the Eastern Suburbso 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 8 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. It is anticipated that the findings of this study will provide theoretical references for the effective control and scientific management of heavy metal pollution in the Huafei River and its surrounding areas.