Pollution Status Of Heavy Metals Research Articles

Heavy metal pollution and risk assessment of tailings in one low-grade copper sulfide mine

Analyzing the pollution level and ecological risk of heavy metals in tailings is a necessary step for conducting revegetation after a tailings pond’s closure. Herein, we determined the heavy metal pollution status and ecological risk in one low-grade copper sulfide tailings pond using chemical and mineralogical analysis, chemical extraction, and ecological risk assessment. The results showed that the low-grade copper sulfide tailings displayed a low pollution status and exhibited a very low ecological risk. Among six heavy metals (Cu, Pb, Zn, As, Cr, and Cd), only Cu (53.7 mg/kg) slightly exceeded its standard value limit (50 mg/kg), and was the main pollutant in the tailings. Due to its high toxicity, As had the maximum contribution to the potential ecological risk in the tailings. Pb, Zn, Cr, and Cd in the tailings were practically of no pollution, and at low or none potential ecological risk. In order to conduct revegetation in the tailings pond, more attention should be paid to the acidity change of tailings and its impact on the chemical activity and bioavailability of Cu and As. This research provides a theoretical basis for heavy metals risk control and revegetation in the low-grade copper sulfide tailings pond.

Health and ecological risks assessment of heavy metals and metalloids in surface sediments of Urmia Salt Lake, Northwest of Iran.

Urmia Lake, in the northwest of Iran, is the largest body of saline water in the Middle East, which has been desiccated in recent decades. To investigate the pollution status and ecological-health risks of heavy metals and metalloids in the surface sediments of this lake, 26 sediment samples were collected along the salt marshes of the lake and were analyzed for heavy metals and metalloid concentrations. The potential ecological risk assessment was carried out using enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), and potential ecological risk (Eri) standard indices. The average concentrations (mg kg-1) of heavy metals and metalloids were as follows: Fe (11,714) > Sr (320.8) > Mn (274.3) > V (28.5) > Cu (24.7) > Zn (21.2) > As (17.3) > Ni (14.8) > Cr (12.6) > Pb (11) > Co (4.0) > U (1.7), Hg (0.6) > Mo (0.36). The concentrations of As, Hg, and Sr in lake sediments were higher than geochemical background values. The non-carcinogenic risks caused by heavy metals and metalloids were insignificant regarding health risks. Levels of carcinogenic risk for metal(loid)s were in the acceptable ranges (10-6-10-4). The ecological risk was low, except for As, Sr, and Hg which showed moderate to significant EF, Igeo, and CF values. Arsenic and Sr were enriched in the surface sediments in desiccated parts of the lake due to complete lake water evaporation. It seems that further drying of the lake increases the potential ecological risk of heavy metals and metalloids in the surface sediments of Urmia Lake.

Spatial Distribution and Risk Assessment of Heavy Metals in Surface Sediments from the Middle and Upper Reaches of the Yangtze River

The hydrological regime of rivers significantly changes after dam impoundment, which in turn affects the particle composition and heavy metal fractions of the river sediments. From June to July 2019, the sediments from 26 sampling sections were collected along the main stream of the Yangtze River from Panzhihua City in the upper reaches of the Yangtze River to Hukou City in the middle reaches of the Yangtze River. The concentrations and fractions of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn were measured using the BCR three-step extraction procedure. The pollution status and potential ecological risk of heavy metals in sediments were evaluated using the geo-accumulation index, the sediment quality guideline, and the risk assessment coding method (RAC). The results showed that the average particle size of sediments in the upper reaches of the Yangtze River (Jinsha River cascade reservoir section and the Three Gorges reservoir section) decreased from upstream to downstream, the total concentrations of As and Zn increased, and the variation trend in the middle reaches was not obvious. The content of clay particles was significantly positively correlated with the acid-soluble fraction concentrations of Cd and Ni. Cd was mainly in the residual fraction (59.26%) and acid-soluble fraction (24.67%). Large parts of Cr and Ni were residual fractions accounting for 92.41% and 83.41%, respectively. As, Co, Cu, Pb, and Zn were mainly in the residual fraction and the reducible fraction. The order of decrease for the pollution degree (Igeo) of As, Cd, Co, Cr, Ni, and Zn was the Jinsha River, the middle reaches of the Yangtze River, and the Three Gorges Reservoir. The decrease order of bioavailability (RAC) of Cd, Co, Cr, Cu, Ni, and Zn was the Three Gorges Reservoir, the Jinsha River, and the middle reaches of the Yangtze River. The bioavailability of As and Pb decreased in the order of the middle reaches of the Yangtze River, the Three Gorges, and the Jinsha River. According to the classification of the RAC, Cd in the Three Gorges Reservoir area exhibited a high risk with the RAC accounting for 48.44%. Cu, Ni, and Zn showed a low or medium risk.

Contamination And Health Risk Assessment Of Heavy Metals Form A Typical Pb-zn Smelter In Northwest China

Soil contamination by heavy metals due to metal smelting activities poses a serious threat to the ecological environment and to human health, as it is considered to be one of the most significant sources of soil pollution. The objective of this study was to analyze the pollution status and human health risks of heavy metals emitted from metal smelting activities of a Pb-Zn smelter. The results of mean values of Zn, Pb, Cd, Cr, Cu and Mn should be incorporated and mention the status in respect to background value. Contamination levels of heavy metals were evaluated using the potential ecological risk index (RI). Possible human health risks were assessed using the health risk assessment model developed by the US EPA. The results showed that the soils are seriously polluted, and migrated down the soil vertical profile. The index of RI indicated a very high potential ecological risk overall in the entire study area, especially for Cd. The health risk analysis showed that adults and children are exposed to significant non-carcinogenic health risks, and there are higher non-carcinogenic health risks for children than for adults. Additionally, the carcinogenic risks of Cr were higher than those of Cd for the two population groups, and children were more susceptible than adults. These results are useful for management, prevention, control and remediation of heavy-metal contamination. Meanwhile, this research provides methods, experiences, and reference to other study of similar heavy-metal soil pollution. Bangladesh J. Bot. 51(4): 995-1015, 2022 (December) Special

Mangrove (Avicennia marina) parts as proxies in marine pollution of Nizampatnam Bay, East Coast of India: An integrated approach

This study focuses on the assessment of heavy metals (HM) concentration and pollution status of the Nizampatnam Bay, east coast of India, from mangrove plant parts (roots and leaves) and sediment samples. This is the first of its kind work (comparison of data from both mangrove and sediment samples) from the third largest mangrove ecosystem in India. To carry out this work, plant (Avicennia mariana) and sediment samples were collected from five stations. The collected samples were carefully subjected to the laboratory methods and heavy metal concentrations were determined by using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The obtained results were juxtaposed with the optimal values of world surface pollution rock averages, and noticed heavy metals such as Cd and Cu exceed the optimal values. To know the contamination levels and the chemical elements that contribute to the pollution, various environmental indices, viz., contamination factor, enrichment factor, geoaccumulation index, and pollution load index were, carried out on the sediment sample data. To ascertain the mangrove plant's capacity (in the study area) for accumulation and translocation of heavy metals in different parts of the plants, factors such as bio-concentration and translocation were calibrated.

Pollution status and risk assessment of heavy metals in the sediment of a historically contaminated lake treated by oxidation pond in China.

Sediment plays animportant role in controlling biogeochemical cycling of heavy metals in aquatic environment. The Ya-Er Lake is a typical lake which was historically contaminated by heavy metals in Hubei province, China. After industries surrounding the Ya-Er Lake being shut down, oxidation pond treatment and dredging program were conducted for pollution management since 1970s. To date, the Ya-Er Lake has been used for aquaculture for several decades. However, the status of heavy metal levels and ecological risks in this lake remains unclear. Herein, concentrations, chemical fractions, and risk assessment of heavy metals were investigated in the Ya-Er Lake sediment. Results showed that concentrations of heavy metals in the Ya-Er Lake sediment were higher than other reported lake systems, suggesting that heavy metal pollution in the Ya-Er Lake is still serious. Relatively higher proportions of carbonates bound form of Cd and Ni indicated high-risk potential of these two heavy metals, and Cd and Ni should be listed as the primary heavy metal pollutants in the Ya-Er Lake according to the results of potential ecological risk index (PERI) and sediment quality guidelines (SQGs). The risk assessment code (RAC) analysis showed that Ni and Cd poses higher bioavailability and mitigation potential, and may affect the Ya-Er Lake ecosystem and downstream aquatic environment. These findings reflected that oxidation pond treatment and dredging sediment to near place are not effective to control heavy metal pollution, and a long-term ecological risk is still posed to surrounding aquatic environment. Our study provides scientific basis on pollution control and management in aquatic system contaminated by heavy metals.

Pollution Status of Sediment from a Remediated Crude Oil Produced Water Discharge Channel Using Various Indices

The Forcados Terminal effluent discharged channel was remediated about twenty years ago with recommendation for periodic assessment of the organic and inorganic contaminants in the area. Forcados Terminal is in Delta State, Nigeria. This study was carried out to evaluate heavy metals pollution status of sediments in the remediated crude oil effluent discharge channel. A total of sixteen sediments samples were collected from ten sampling locations using grab sampling technique in October 2019 (wet season) and February 2020 (dry season). Heavy metals were determined in all the samples using atomic absorption spectrophotometry after digestion with aqua regia. The results showed that the concentrations of the sediment samples (mg/kg) ranged from <0.01-0.05, <0.01-0.91, <0.01-3.46, 13.2-45.3, 14.7-64.1, 5.56-105, 3.10-108, 0.14-5.86, 78.8-289, 28.2-254 and 3529-7773 for Hg, As, Cd, Pb, Cr, Ni, Cu, V, Mn, Zn and Fe. Hg and As were generally not detected in the sediments. On the average, the geoaccumulation index of Cd in the sediments falls into the moderately polluted category while the geoaccumulation index of all the other metals falls into the practically unpolluted category. On the average, the Contamination/Pollution index (CPI) value of Cd was > 1 which indicates that the sediments were polluted with Cd but the CPI values of other heavy metals were < 1 which indicates that these sediments were contaminated with the other heavy metals.

Risk Assessment and Sources of Heavy Metals in Farmland Soils of Yellow River Irrigation Area of Ningxia

The farmland environment is directly related to the quality and safety of agricultural products. In order to understand the characteristics and main influencing factors of heavy metals in farmland soil in the Yellow River irrigation area of Ningxia, sampling and monitoring were conducted for five consecutive years from 2017 to 2021, and the distribution characteristics and correlation of heavy metals were analyzed. The pollution status and potential ecological risks of heavy metals were evaluated, and the main sources of heavy metals in farmland were analyzed. The results showed that the average values of Pb, As, Zn, Ni, Cu, Hg, Cr, and Cd in the soil of the Ningxia Yellow River irrigation area were 19.74, 11.67, 66.88, 29.09, 22.55, 0.03, 62.27, and 0.19 mg·kg-1, respectively, which were enriched to some extent compared with the background values of the soil environment in Ningxia. Among them, Hg and Cd had middle- and high-grade ecological risk points; however, none of them exceeded the control value of agricultural land soil pollution risk, and all sampling sites had no high-risk or extremely high-risk levels. The results of source analysis based on positive matrix factorization (PMF) and correlation analysis showed that there were five main sources of heavy metals in farmland soil in the study area: natural sources, mixed sources of industrial and mining activities and the production and life of residents, transportation sources, agricultural production activities sources, and industrial sources, with contribution rates of 26.54%, 25.59%, 22.52%, 15.63%, and 9.72%, respectively. On the whole, the heavy metals in farmland soil in the Ningxia Yellow River irrigation area did not exceed the standard, and there was no high-level ecological risk. The production environment of the farmland soil was good, but the contribution rate of human activities to soil heavy metals was large.

Variation in pollution status, sources, and risks of soil heavy metals in regions with different levels of urbanization

Soil heavy metal (HM) pollution is an increasing threat to ecosystem integrity and human health with rapid urbanization. Nevertheless, how soil HMs vary with the process of urbanization remains unclear. Here we used index evaluation, spatial analysis, and a positive matrix factorization (PMF) model to determine the pollution characteristics and sources of eight soil HMs (Mn, Cr, Cu, Zn, As, Cd, Pb, and Ni) among regions with different urbanization levels (urban area, suburb, and ecoregion) in Baoding City, Northern China. We also assessed the risks posed to the ecosystem and human health using risk assessment models. The results indicated that the mean levels of Cu, Zn, As, Cd, and Pb in the study area exceeded the soil environmental quality standards by 10.7 %, 10.7 %, 12.5 %, 23.2 %, and 3.57 %, respectively. A pronounced regional spatial distribution was discovered with high levels in suburban areas. Both the geo-accumulation index and potential ecological risk index revealed significantly higher HM contamination in suburban areas than in urban or ecoregion areas. Source apportionment based on the PMF model and correlation analysis showed that soil HMs in suburban areas primarily originated from agricultural activity, industrial sources, and natural sources. Those in urban soils originated from industrial sources, urban traffic, and natural sources, whereas those in ecoregions derived from natural sources and agricultural activity. The complex sources of soil HMs in suburban areas resulted in the highest carcinogenic risks to children health, followed by the ecoregion, but not in urban areas. This study identified the differences in pollution levels, sources, and risks of soil HMs among regions with different urbanization levels and can guide future efforts to mitigate and manage soil HM pollution during urbanization.

Spatial Risk Assessment and Source Identification of Heavy Metals in Riverine Sediments of Lake Chaohu Basin, China

In recent decades, the rivers in Lake Chaohu Basin have been subjected to intensive anthropogenic disturbance. However, previous studies have mainly focused on Lake Chaohu, and the inflowing and outflowing rivers have not been well examined. To characterize the pollution status of heavy metals in the entire Lake Chaohu Basin, 8 heavy metals (Cu, Zn, Pb, Cr, Cd, As, Hg, and Ni) in riverine surface sediments were measured at 131 sampling sites in 7 subbasins. Spatial patterns and pollution characteristics were evaluated based on the potential ecological risk, geoaccumulation, and pollution load indexes. The results showed that Cr and Hg were the 2 main heavy metal pollutants in the surface sediments, with mean contents exceeding background values by a factor of 4.12 and 2.64, respectively. The Nanfei River (NF), which flows through Hefei city (a metropolis of the capital of Anhui Province), is characterized by large amounts of domestic and industrial waste discharged into the water body due to human activities; this waste caused serious heavy metal pollution, and NF substantially contributed to heavy metal pollution inputs to Lake Chaohu. Several subbasins in the southern part of Lake Chaohu Basin exhibited high concentrations of Cu in surface sediments, mainly from mining and agriculture. This study identified the main contamination areas, revealed the possible sources of each heavy metal, and can serve as a reference for the remediation and management of Lake Chaohu Basin to ensure the water safety of Lake Chaohu.

Health risk assessment of heavy metal exposure through vegetable consumption around a phosphorus chemical plant in the Kaiyang karst area, southwestern China.

The phosphorus chemical industry is an important source of heavy metals in farmland. Vegetables grown on contaminated soil potentially impose adverse effects on human health. In this study, the pollution status and health risks of heavy metals in vegetables around a phosphorus chemical plant in Kaiyang County, Guizhou Province, southwestern China, were assessed, and the low-accumulation vegetables were screened by bioaccumulation factor (BAF) and cluster analysis. Results showed the average concentrations of Hg, As, Cd, Pb, Cr, Mn, Co, and Zn in vegetables were 0.015, 0.728 0.382, 0.227, 0.850, 27.227, 0.525, and 6.438mg/kg, respectively. The single-factor pollution index showed that Cd was moderately polluted, and Cr, Hg, As, and Pb were slightly polluted. The Nemerow pollution index showed that the overall heavy metal pollution was classified as moderately polluted. The accumulation of heavy metals in different vegetables varied greatly, and chard, crown daisy, chayote, pumpkin, eggplant, white radish, sweet potato, carrot, and potato were selected as the low-accumulator vegetables. The consumption of all vegetables except chayote poses both carcinogenic and noncarcinogenic risks; among them, the consumption of sweet potato leaves has the highest health risks. The local population needs to adjust plantation structure and change dietary habits, and government should strengthen the management of phosphorus chemical plant pollution.

Spatial Distribution Characteristics of Heavy Metals and Pollution Analysis Methods

With the rapid development of urban economy and the continuous increase of urban population, the discharge and improper disposal of a large number of industrial wastes, urban domestic garbage, sludge and other pollutants have led to the continuous accumulation of heavy metals in the soil, which has increased the pollution load of heavy metals in the soil, leading to the increasingly serious heavy metal pollution of urban topsoil in China. Heavy metal pollution of urban soil is one of the important indicators that can effectively reflect the status of urban environmental pollution. Therefore, the verification of urban soil environment anomalies and the application of verification data to urban environmental quality assessment, as well as the study of the evolution model of human activities affecting urban soil environment, have increasingly become the focus of attention. Based on the analysis of a large number of relevant documents and previous work, the sources, hazards and pollution status of soil heavy metal pollution in some regions of China are briefly summarized, and the characteristics of five commonly used assessment methods of soil heavy metal pollution (single pollution index method, comprehensive pollution index method, geo accumulation index method, potential ecological risk index method, principal component analysis method) are briefly analyzed and summarized, It is expected to provide some reference for the investigation and treatment of soil pollution.

Comparison of Pollution Levels, Biomagnification Capacity, and Risk Assessments of Heavy Metals in Nearshore and Offshore Regions of the South China Sea.

Seawater and fish were collected from nearshore (Pearl River Estuarine, PRE) and offshore (middle of the South China Sea, MSCS) regions of the South China Sea (SCS) to determine the heavy metals (HMs) pollution status and biomagnification characteristics. Results show that Cu in PRE seawater was moderately contaminated. Overall pollution risk of seawater were PRE (3.32) > MSCS (0.56), whereas that of fish was MSCS (0.88) > PRE (0.42). δ13C and δ15N exhibited distinguished characteristics for PRE and MSCS fish, indicating the diverse energy sources, nitrogen sources, and food web structures of nearshore and offshore regions. Cu was biomagnified whereas Pb and Ni were biodiluted in offshore fish. Hg presented significant biomagnification in both of nearshore and offshore fish. Finally, the target hazard quotient of Hg (1.41) in MSCS fish exceeded the standard limit, which was posed by high Hg concentration and consumption rate of offshore fish.

Evaluation of Heavy Metal Content, Sources, and Potential Ecological Risks in Soils of Southern Hilly Areas

In order to explore the characteristics of soil heavy metal pollution and ecological risk status in southern hilly areas, a hilly area of a southern province was selected as the research area, using soil samples collected at 60 points in 2017. The single factor pollution index (Pi), Nemero comprehensive pollution index, and potential ecological risk index (RI) were used to evaluate the content characteristics and potential ecological risks of eight heavy metal elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn), and positive definite matrix factor analysis models (PMF) were used to analyze their sources of pollution. The results were as follows:① the content of eight heavy metal elements in the study area exceeded the standard, and the Nemeiro comprehensive pollution index showed that the proportions of light, moderate, and heavy pollution in the study area were 63%, 8%, and 2%, respectively. Unpolluted and lightly polluted samples accounted for 27% and were thus basically lightly polluted. ②The comprehensive potential ecological risk index showed that the RI of soil heavy metals was 39.58-224.15, the proportions of samples with low and medium ecological risks were 73.33% and 25%, respectively, and the proportion of sites with severe ecological risks was 1.67%. Although this site had the highest ecological risk, the content of heavy metals was lower than the background value of soil elements in the province. ③Six pollution sources were obtained through the PMF model:natural sources, agricultural activity sources, mixed sources composed of copper mining and transportation, industrial activity sources, transportation sources, and domestic waste emission sources. The contribution rates of each source were 24.8%, 17.7%, 17.7%, 17.6%, 12.0%, and 10.2%, respectively.

Heavy metal pollution status and deposition history of mangrove sediments in Zhanjiang Bay, China

Mangroves have high ecological service value and play an important role in achieving carbon neutrality. However, the ecological services provided by mangroves are gradually declining due to the threat of various pollutants, especially heavy metal (HM) pollution. Researching the status and history of heavy metals (HMs) in mangrove sediments improves understanding of how mangroves can be protected. We studied the Zhanjiang Bay mangroves, which is an important part of the Zhanjiang Mangrove National Nature Reserve, and is greatly affected by human activities, as an example. We analyzed the pollution levels and deposition process of HMs and their influencing factors. In the mangrove surface sediments of Zhanjiang Bay, Pb, Cr, and Co were slightly to moderate enriched and Cu was moderate-heavy enriched. Zn and Hg showed moderate-heavy enrichment and heavy enrichment, respectively. Cu, Zn, Hg, and Co were 1.5, 1.88, 2.66, and 1.27 times the local background, respectively. Cu, Zn, and Hg mainly originated from anthropogenic sources, and Co may have derived from natural sources. The HM data of mangrove sedimentary cores in Zhanjiang Bay were obtained for the first time; high HM content appeared in the deep layer of the cores but not in the mangrove surface sediments. Both cores were well documented for the effects of natural and anthropogenic factors on the deposition process of HMs. Among them, the high enrichment of Hg in 1909–1921 may be closely related to human activities rather than natural formation. Before 1954, dense mangroves favored the accumulation and gradual increase of HMs. The intense human activity in 1945–1963 during the period of economic construction and reclamation of the Nansan Island Engineering led to significant increases in Cu, Zn, Pb, Cr, and Co, which reached their highest values in more than one hundred years. After 1963, anthropic factors such as deforestation and conversion to aquaculture sharply reduced mangrove area. Reclamation engineering enhanced tidal erosion. Natural factors such as precipitation, storm surge, sea-level rise, and high tides have accelerated the erosion and dilution of mangrove sediments in Zhanjiang Bay. These factors have led to the gradual reduction of HM content in sedimentary cores.

Heavy metal pollution characteristics and potential ecological risk assessment of soils around three typical antimony mining areas and watersheds in China

China is the largest antimony resource globally. The mining and smelting of antimony will inevitably have a significant impact on the surrounding and downstream farmlands of the mining area, Therefore, it is necessary to understand the pollution characteristics of antimony and evaluate its potential environmental risks. In this paper, three typical antimony mining areas were used as research districts to analyze the contents of heavy metals in soils of the mining areas and watersheds. The single-factor pollution index method, Nemerow comprehensive pollution index method, geo-accumulation index method, and potential ecological risk index method were used to comprehensively evaluate the pollution status and ecological risk of heavy metals in soils around the mining areas. The soil around the Lengshuijiang tin mine was polluted by As, Cd, Zn, and Sb, it was a heavily polluted soil and at a high ecological risk level. The arable soil around the Nandan tea mountain antimony mine was polluted by As, Cd, Cu, Pb, Sb, and Zn, and it was a heavily polluted soil with very high ecological risk level. The soil around the Xunyang antimony mine was mainly polluted by Sb and it was a moderately polluted soil with moderate ecological risk level. The results revealed that the overall soil heavy metal levels in the Lengshuijiang mining area and the Nandan mining area were in a high-risk state, most likely due to the mining and smelting of metal ores and the weathering of mineralised rocks. showing a high-potential ecological risk in these mining areas. We expect to provide a scientific basis for the safe utilization of farmland and pollution control around the antimony mining areas and watersheds in China.

Heavy metal pollution in the soil of contaminated sites in China: Research status and pollution assessment over the past two decades

Contaminated sites are receiving more and more attention internationally because they pose a serious threat to the ecological environment and human health. Although the research focused on heavy metals pollution in the soil of contaminated sites has been rapidly developing over the past two decades, systematic research status analysis and pollution assessment are still lacking. Here, through the “front page filtering” script and successive screening of the relevant studies, the research status of heavy metal pollution in the soil of contaminated sites worldwide and especially in China had been synthetically analyzed. The result showed that China and USA were the most active countries in related research, and the main research subjects were the assessment of contaminated sites and remediation methods. The keyword co-occurrence network of heavy metal contaminated sites in China was divided into three clusters, focusing on different environmental media, physical-chemical remediation and phytoremediation technologies. The types of contaminated sites in China mainly included mining areas (the largest proportion), industrial zones, sewage irrigation, and dismantling sites, etc. Cd and Pb were the most widely studied heavy metal in China. The pollution of heavy metals in the soils of contaminated sites was ranked as: Cd > Pb > Cu/Zn/Hg > As/Cr > Ni, and it was more serious in southeast China than northwestern China.

Heavy metal pollution and risk assessment of farmland soil around abandoned domestic waste dump in Kaifeng City

In order to understand the heavy metal pollution and potential ecological risk of farmland soil around the waste dump in the eastern suburb of Kaifeng clearly and provide a scientific basis for the remediation of heavy metals in farmland soil, the single factor pollution index method, Nemero comprehensive pollution index method and Hakanson potential ecological risk method were used to evaluate the heavy metal pollution status and potential ecological risk degree of farmland in this area at the same time. The ArcGIS software was employed to map the spatial distribution of heavy metal pollution and potential ecological risks. The results show that the average values of heavy metals in this area are higher than the soil Background Value of Kaifeng City, and the problem of excessive heavy metals in the soil is significant. Of the 41 surface soil samples, Cd’s heavy and moderate pollution rates were up to 15% and 38%, respectively, and the potential ecological risk caused by Cd element was quite serious, and more than 35% of the soil samples were at higher potential ecological risk. The comprehensive review results showed that 38% of the samples were heavy pollution, and 23% of the sample soils were at higher potential ecological risk. The spatial distribution characterized by the levels of most heavy metals and the extent of potential ecological risk showed high levels in the center of the dump, with a gradual decrease towards the outward radiation zone. This means dust and leachate from waste dump are major causes of heavy metal contamination and potential ecological risks. In addition, the retrieval of the waste mound soil from landfills by villagers as soil fertilizer for rapeseed also caused, to some extent, the transfer of the waste mound contaminants.

Assessment of Heavy Metal Pollution Status in Surface Soil of a Nigerian University

The problem of urban soil contamination with heavy metals due to rapid urbanization and industrialization has been a major concern in recent years. A university can be considered as a product of industrialization and urbanization which is associated with different activities that may induce heavy metals pollution into the environment. Therefore, this research work assessed the contamination level of chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) and manganese (Mn) in surface soils of Afe-Babalola university (ABUAD) using various indices. Soil samples were taken from ten (10) different functional sites in the university. These samples were taken to the laboratory and analyzed for chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) and manganese (Mn) using standard method. The mean concentrations of copper (Cu), chromium (Cr) and lead (Pb) were up to 0.75, 0.66 and 0.36 mg/g respectively, while manganese (Mn) and zinc (Zn) were 1.37 and 0.49 mg/g respectively. The average concentration of manganese (Mn) was comparable to its corresponding natural background value, but the average concentration of chromium (Cr), copper (Cu), zinc (Zn) and lead (Pb) were higher. They were approximately of the ratio 1:7, 1:2, 1:3 and 1:2 respectively compared to their corresponding natural background value. The multivariate statistical analyses indicated that vehicles, power generating sets, petrol station, machine workshops, production plants and emissions from outdoor roasted food spots were the major sources of heavy metals contamination on the universitys’ soil. The results from contamination indices and assessment showed that the contamination level of soils within the university can generally be classified as moderately contaminated. Therefore, periodic assessment of the sources and associated ecological risks of the heavy metals is highly recommended. This is to enable decision-makers to effectively manage the environment in the manner that will preserve public and ecosystem health.

Accumulation Characteristics and Pollution Evaluation of Soil Heavy Metals in Different Land Use Types: Study on the Whole Region of Tianjin.

Heavy metal pollution in soil has received much attention in recent decades. Many studies have analyzed the interaction between specific soil quality and soil heavy metal pollution. However, there is little information about the pollution status, spatial distribution and pollution sources of heavy metals in the province of Tianjin. In this paper, the distribution characteristics and pollution sources of heavy metals in soil were studied by means of the surface soil of Tianjin, as the study area and object, conducted in combination with land use types, using multiple data analysis and multivariate statistics, while the pollution levels were evaluated by various indices. The results showed the mean contents of the seven heavy metals of the studied elements followed an increasing order of Cd (0.15 mg/kg) < As (11.9 mg/kg) < Cu (24.3 mg/kg) = Pb (24.3 mg/kg) < Ni (27.9 mg/kg) < Cr (70.7 mg/kg) < Zn (79.1 mg/kg). The median values of Cr and Ni were lower than the background values and did not exceed the screening values at the points, and the median values of Cu, Zn and Pb were close to the background values, while the median contents of As and Cd were higher than the background values. The highest accumulation of heavy metals was found in grassland, and the coefficient of variation of heavy metal contents were higher in garden land, industrial and mining storage land, residential land and transportation land, indicating that the soil heavy metal contents under these land use types were more significantly disturbed by human factors. The evaluation results of the ground accumulation index method showed that the soil in Tianjin was free of pollution, except for Cd, which was at the non-polluted to moderately polluted level. The Nemero integrated pollution index evaluation method and the pollution load index evaluation method together showed that the integrated pollution levels of heavy metals in Tianjin soils were both at no pollution level/safety level. Apart from Cd and As, which were not correlated, the other heavy metals were correlated with each other two by two. Cd, Pb and Zn were the main pollution contributors from traffic, industry and other anthropogenic factors, while Cr and Ni were the main pollution contributors from soil parent material, and Cu was the main pollution contributor from mining and metal smelting. In addition, As was presumed to be the main source of pollution contribution from agriculture and surface runoff.