Average Concentrations Of Cr Research Articles

Pollution Characteristics and Ecological Risk Assessment of Heavy Metal in the Coast Sediments along Power Plant-Sanshimu Village of Yangzong Lake, Yunnan Province

To explore the current situation of heavy metal pollution in Yangzong Lake areas, the contents of Cu, Zn, Ni, Cr, Fe, Mn, V, Mo, Co, Sr, Li, Be, Cd, As, Pb, Al, Ba and Ti in 40 coast sediment samples along Power Plant-Sanshimu Village were determined. Single factor pollution index, enrichment coefficient and geoaccumulation index were used to evaluate the heavy metal pollution. The results showed that concentrations of Cu, Cr, Co and Be in all samples exceeded their natural background values. The average concentrations of Co, Cd, Cu, Be, Cr, Mo, V, As, Ni, Li, Zn, Mn, Sr and Fe were higher than their natural background values, while Pb, Al, Ba and Ti were opposite. Co, Cd, and Cu were the highest degree of pollution, followed by Be, Cr, Mo and V. Potential ecological risk index indicated a moderate-strong ecological risk. Cd, Co, As and Cu were the main ecological risk factors in this region.

Determination of trace elements in the nanometer, ultrafine, fine, and coarse particulate matters in an area affected by light vehicular emissions in the city of Rio de Janeiro.

The objective of this work was to determine the trace element composition in the nanometric, ultrafine, fine, and coarse particulate matters (PM) found in the surrounding area of the UERJ Chemical Technology Applications Institute, using a MSP 120 MOUDI II cascade impactor. After acid extraction, the elements were analyzed via ICP-OES, and the results obtained were treated statistically. The average concentrations of the nanometric, ultrafine, fine, and coarse particles were 11.8, 8.2, 7.7, and 7.1 μg m-3, respectively. The total average concentration of Cd, Ni, Pb, Cr, and Fe complied with the air quality standards recommended by US EPA and WHO. When compared with other locations, the PM fractions found in this study were 1.1 to 346 times greater. Through the calculation of Pearson's correlation coefficient, a high correlation was observed between most of the trace elements studied, especially in the ultrafine, fine, and coarse fractions, which suggests that they are probably caused by the same sources of vehicular emissions. The enrichment factor was calculated to estimate the possible sources. Since Cd, Cu, Pb, and Mo are enriched by anthropic sources, they are probably influenced by vehicular emissions, in particular the wear on tires and brakes, and the burning of fossil fuel.

Current Status and Temporal Trend of Potentially Toxic Elements Pollution in Agricultural Soil in the Yangtze River Delta Region: A Meta-Analysis.

Potentially toxic elements (PTEs) pollution in the agricultural soil of China, especially in developed regions such as the Yangtze River Delta (YRD) in eastern China, has received increasing attention. However, there are few studies on the long-term assessment of soil pollution by PTEs over large regions. Therefore, in this study, a meta-analysis was conducted to evaluate the current state and temporal trend of PTEs pollution in the agricultural land of the Yangtze River Delta. Based on a review of 118 studies published between 1993 and 2020, the average concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni were found to be 0.25 mg kg−1, 0.14 mg kg−1, 8.14 mg kg−1, 32.32 mg kg−1, 68.84 mg kg−1, 32.58 mg kg−1, 92.35 mg kg−1, and 29.30 mg kg−1, respectively. Among these elements, only Cd and Hg showed significant accumulation compared with their background values. The eastern Yangtze River Delta showed a relatively high ecological risk due to intensive industrial activities. The contents of Cd, Pb, and Zn in soil showed an increasing trend from 1993 to 2000 and then showed a decreasing trend. The results obtained from this study will provide guidance for the prevention and control of soil pollution in the Yangtze River Delta.

Chromium Bioaccumulation by Plants and Grazing Livestock as Affected by the Application of Sewage Irrigation Water: Implications to the Food Chain and Health Risk

The aim of this study was to determine the influence of sewage water irrigation on chromium (Cr) accumulation in soil and forage species and to assess the health risk of grazing livestock via forage consumption. The experimental design of the research and all experiments were done in Sargodha University Botanical Department. Measurement of Cr in water samples and soil and plant samples prepared for analysis by wet digestion was done using atomic absorption spectrophotometer (AA-6300 Shimadzu Japan). The average Cr concentrations in soil samples, forage crops and in water were determined. In the root samples of forage species, the highest concentration was 0.625 mg/kg (dw) in winter forage T. alexandrinum and the lowest mean concentration was 0.053 mg/kg (dw) in summer forage S. bicolor. In the leaf samples of forage species, the highest mean concentration of Cr in leaves was 0.583 mg/kg (dw) occurred in T. alexandrinum in winter forage and the lowest mean concentration was 0.035 mg/kg (dw) occurred in E. colona grown in summer forage. The present Cr values in the leaf samples of forages species were lower than this permissible limit. In the present study, the values of health risk index were lower than 1 in case of all Cr values. So, it can be said that forage species irrigated with sewage water in the study area is safe for consumption of livestock. However, though the general values were lower than the permissible maximum limit, it was observed that the metal accumulation in the forage species irrigated with sewage water was higher. Therefore, especially in agricultural applications, attention should be paid to contamination of soil and food chain components when watering with wastewater.

Spatial distribution and pollution assessment on the main nutrients and heavy metals in sediments of Lake Gehu, Taihu Basin after removing the aquaculture net<sup>*</sup>

为评估滆湖围网拆除工程实施效果，采用高密度网格化布点方法，系统分析滆湖沉积物营养盐和重金属的空间分布和污染特征；并基于有机氮评价方法、综合污染指数评价方法、重金属地质累积指数法和重金属潜在生态风险评价方法进行污染风险评价.结果表明，滆湖沉积物总氮（TN）、总磷（TP）和总有机碳（TOC）的平均含量分别为（3709±1004）mg/kg、（1127±650）mg/kg和（78.39±23.88）mg/g，三者空间分布特征较为一致；营养盐综合污染指数评价表明，全湖整体为重度污染，其中全湖TN均处于重度污染状态，TP绝大部分区域也处于重度污染状态.沉积物重金属Zn、Cr、As、Pb、Ni、Cu、Cd的平均含量分别为（170.62±47.25）、（105.18±34.91）、（68.55±10.86）、（52.43±14.73）、（44.04±11.93）、（42.57±12.43）、（1.55±1.06）mg/kg，整体上呈现出由南向北、自西向东逐渐增加的趋势，重金属含量最高值在湖区东北角；地积累指数法和潜在生态风险指数法评价结果均表明Cd和As是主要的生态风险贡献因子，其中Cr和Ni的污染程度表现为清洁，Cr、Ni、Cu、Zn和Pb的单项潜在生态风险等级表现为轻微风险.与围网拆除前比，湖中区西南部沉积物营养盐含量无显著变化，湖南区南部沉积物营养盐状况明显改善，但其余各区域沉积物营养盐状况均有不同程度的恶化；湖区沉积物中重金属元素平均含量均有极大程度的降低，降幅在29.50%~80.45%之间，表明在外源污染输入得到一定控制时，围网拆除在控氮、控磷效果及改善重金属污染状况方面有着积极作用.;In this study, the spatial distribution characteristics of the main nutrients and heavy metals in sediments of Lake Gehu after completely removing the aquaculture net were investigated using high-density sampling methods, and their potential ecological risks were assessed based on organic nitrogen index, integrated pollution index, geo-accumulation index (I_geo) and potential ecological risk index. Results showed that the average contents of TN, TP and TOC were (3709±1004) mg/kg, (1127±650) mg/kg and (78.39±23.88) mg/g, respectively. The spatial distribution characteristics of TN, TP and TOC were relatively consistent, generally, those of the middle and upper part of the lake was higher than those of the southern part except the northern. Integrated pollution index showed that the whole lake was heavily polluted, meanwhile, the lake-was severely TN-polluted and slightly TP-polluted in most areas. The average contents of heavy metals Zn, Cr, As, Pb, Ni, Cu and Cd were (170.62±47.25), (105.18±34.91), (68.55±10.86), (52.43±14.73), (44.04±11.93), (42.57±12.43) and (1.55±1.06) mg/kg, respectively. Generally, the heavy metal contents increased from south to north, from west to east, and reached the highest level in the northeast corner. I_geo and the potential ecological risk assessment indicated that Cd and As were the most polluted elements and led to high potential ecological risk. According to the result of I_geo, Cr and Ni were not polluted, while Cr, Ni, Cu, Zn and Pb were at a slight potential ecological risk. Since the aquaculture net was being demolished, there was no significant change in the nutrient content in the southwestern part of the lake, and the nutrient status in the southern end of the Gehu Lake area was significantly improved, but the nutrient status in the rest of the area had deteriorated to varying degrees; the heavy metal content has a great reduction, ranging from 29.50% to 80.45%, indicating that when the input of external pollution is controlled to a certain extent, the removal of the fence has a positive effect on the effect of controlling nitrogen and phosphorus and improving the pollution of heavy metals.

Assessment of Dissolved Metals/Metalloids in the Eastern Black Sea Rivers of Turkey

There are many fresh water inputs to the Black Sea that differ significantly from each other in terms of both the water level and the extent of the river basin. Seasonal distributions of dissolved metal/metalloid concentrations were measured using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) in 13 rivers (Kizilirmak, Yesilirmak, Melet, Pazarsuyu, Aksu, Harsit, Degirmendere, Solakli, Iyidere, Buyukdere, Firtina, Caglayan, and Kapistre) discharge of waters to Eastern Black Sea coast of Turkey and the results were compared in this study. The highest mean levels were found as aluminium (Al): 174 μg/L, chromium (Cr): 1.02 μg/L, manganese (Mn): 56 μg/L, copper (Cu): 3.2 μg/L, lead (Pb): 0.37 μg/L in Melet and iron (Fe): 130 μg/L, arsenic (As): 3.9 μg/L, antimony (Sb): 2.2 μg/L in Yesilirmak and cobalt (Co): 0.20 μg/L, nickel (Ni): 3.4 μg/L, molybdenum (Mo): 1.5 μg/L in Kizilirmak rivers. The highest mean concentration of zinc (Zn): 68 μg/L was determined in Degirmendere and the highest mean cadmium (Cd) concentration (0.29 μg/L) was measured in Harsit. The lowest average Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb concentrations were detected in the Caglayan. The rivers were grouped in three separate groups according to PCA analysis. The abundance of As, Ni, Co, Sb, Mo, Cr elements were higher in the first group of rivers characterized by a large river basin, while the abundance of Al, Mn, Zn, Cu, Pb elements was higher in the second group of rivers with high erosional effect. The average manganese (Mn) profile in the Melet has been identified as above the legal limits for drinking water determined by Environmental Protection Agency (EPA) and European Commission (EC). The Yesilirmak in terms of antimony (Sb), and the Yesilirmak and the Kizilirmak in terms of arsenic (As) and nickel (Ni) differs greatly compared to other rivers. The highest average Sb concentration had been identified in autumn. Arsenic concentrations of the Kizilirmak and the Yesilirmak were higher than other rivers in all seasons. It has been determined that the extent and geological structures of the river basins and erosional transport play an important role in the classification of rivers in terms of metal/metalloid contents. It has also been shown that knowing the spatial and temporal changes of the water quality of rivers is essential for future projections and protection.

Bioaccumulation of metals in marine fish species captured from the northern shores of the Gulf of Oman, Iran

In this study, the bio-concentration of trace metals (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) was determined in eight edible fish species, which were caught from the northern shores of the Gulf of Oman. For this purpose, a total of 160 fish samples in eight species, originating from different ecological status and trophic levels, were obtained twice, once during the warm season and once in winter. Sample preparation and quantification of the metals were accomplished via the wet digestion method and atomic absorption spectroscopy (AAS). The results showed that the average Cd, Cr, Cu, Fe, Ni, Pb, and Zn concentrations in the edible tissues of the fish, regardless of the species, were 0.14 ± 0.003, 0.75 ± 0.067, 2.18 ± 0.21, 55.55 ± 2.11, 0.35 ± 0.033, 0.49 ± 0.054, 6.78±0.53μgg−1 DW, respectively. The data on metals presence were significantly different between the sampling stations, including for Cu and Pb in the meat of Cynoglossus arel. Therefore, based on the target hazard quotient (THQ), any serious threat to public health would not be due to the consumption of the Gulf of Oman’s captured seafood, and consumers would be able to use seafood safely.

Assessment and zoning of environmental hazard of heavy metals using the Nemerow integrated pollution index in the vineyards of Malayer city

The purpose of the present study was to evaluate and zoning the environmental hazards of heavy metals in the soil using the Nemerow integrated pollution index in vineyards (vineyards) of Malayer city. In this study, after consecutive visits to the study area and reviewing the map of the area, sampling operations were performed in January 2019. Soil sampling was performed based on a systematic random method. A total of 286 samples were collected from topsoil (depth 0 to 20 cm). Of these, 157 samples were located in agricultural lands (gardens and agricultural land) and 129 samples in natural areas (pastures and barren lands). The samples were analyzed by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) and using the flame method. The average concentrations of Cu, Mn, Zn, Cr, As, Ni and Hg are 87.86, 597, 109, 67.12, 47.1, 84.32, and 0.344 mg/kg, respectively. These values are lower than the NIPI index values for these metals. The results showed that there is a positive and significant correlation between Cu and Mn, Cu and zinc, Cu, and As as well as As and Ni. There is also a significant negative correlation between Cu and Hg, As and the electrical conductivity (EC) as well as As and Mn. At present, these soils are not at serious risk of soil contamination with heavy metals.

Identification of the spatial distributions, pollution levels, sources, and health risk of heavy metals in surface dusts from Korla, NW China

Abstract A total of 54 surface dust samples were gathered from Korla in NW China, and the concentrations of six heavy metal elements, such as Hg, Cd, As, Pb, Cr, and Cu, were determined by standard methods. The geostatistical analysis, multivariate statistical analysis, pollution load index (PLI), and the US EPA health risk assessment model were used to analyze the spatial distribution, pollution, and its potential health risk of heavy metals in surface dusts, and the main sources of heavy metals were also identified. The obtained results indicate that the average concentrations of As in surface dust of Korla is lower than the background values determined in Xinjiang soil, whereas the average concentrations of Hg, Cd, Pb, Cr, and Cu elements exceeded the corresponding background values by factors of 3.71, 1.87, 1.96, 1.14, and 1.29, respectively. The higher concentration of analyzed heavy metals is observed in the northeastern and northern parts in the study area. The pollution level of heavy metals decreased in the following order: Hg > Pb > Cd > Cu > Cr > As. Based on the identified concentrations, the collected dust samples are found to be heavily polluted by Hg and slightly polluted by As, and the remaining elements, Pb, Cd, Cu, and Cr, are found to be low polluted. Furthermore, the PLI values of heavy metals in surface dust vary between 0.74 and 2.74, with an average value of 1.40, at the low pollution level. In addition, As in surface dust in the study area is mainly natural source, while Hg, Cd, Cr, Cu, and Pb are mainly anthropogenic sources. Overall, the carcinogenic and noncarcinogenic health risks of the analyzed elements, instigated mainly by oral ingestion of surface dust, are found to be within the acceptable range for both children and adults. As and Cr are the main noncarcinogenic elements, whereas Cr is the major carcinogenic element among the investigated dust-bound heavy metals in Korla.

The quantitative source apportionment of heavy metals in peri-urban agricultural soils with UNMIX and input fluxes analysis

The intensive human activities are the major cause of heavy metals pollution in suburban farmland, which poses threats to soil environment and safety of agricultural products. The combination of spatial analysis (SA), principal component analysis (PCA), input fluxes analysis (IFA) and UNMIX model have precisely analyzed the sources and relative contribution of heavy metals from each source. The results revealed that average contents of Cr, Ni, Cu, Zn, Pb and Cd were 37.82, 13.65, 17.93, 93.78, 48.84 and 0.24 mg kg −1 , respectively. The spatial distribution indicated that parent materials, industrial activities and traffic emissions had significant effects on contents of heavy metals in topsoil. According to UNMIX model, the contribution rates of soil parent material, industrial/ traffic emissions, and agricultural activities to heavy metals in soil were 49.15%, 35.00% and 15.85% respectively. Which indicated largest contribution of natural sources, but input of human activities including industry, transportation and agriculture could not be ignored. The input fluxes analysis (IFA) reveals that atmospheric deposition was main source of heavy metals in soil, followed by fertilizer and irrigation. This study has presented reliable methods for analysis of sources of heavy metals in suburban farmland soil. The combination of UNMIX and IFA can accurately identify and quantify pollution sources. • UNMIX and input fluxes analysis were combined for source apportionment of heavy metals. • Heavy metals in soil mainly come from natural sources, industrial and traffic emissions, and agricultural activities. • UNMIX can be successfully applied for sources apportionment of heavy metals in soil.

Bioaccumulation and risk assessment of heavy metals in soil-crop systems in Liujiang karst area, Southwestern China.

Evaluating the bioaccumulation and health risk of heavy metals in soil-crop systems is essential in Liujiang karst regions. In the current study, the single and comprehensive uptake effects of heavy metals (i.e., Cu, Cr, Cd, As, and Zn) between rice and sugarcane and their rhizosphere soils were investigated. The estimated daily ingestion (EDI), target hazard quotient (THQ), and hazard index (HI) were estimated for health risk assessments. The results showed that the mean contents of Cu, Cr, Cd, As, and Zn in rice soils were 25.8, 168, 1.91, 20.0, and 160 mg/kg, respectively, and those in sugarcane soils were 28.8, 186, 0.44, 31.0, and 108 mg/kg. Rice soils were mainly contaminated by Cd, and Cd and Cr were the main pollutants in sugarcane soils. The average concentrations of Cu, Cr, Cd, As, and Zn in rice grains were 1.79, 0.15, 0.16, 0.11, and 12.7 mg/kg, respectively, and in sugarcanes were 0.10, 0.036, 0.022, 0.006, and 0.38 mg/kg. Both crops tended to take up Cd more effectively, and rice grains exhibited higher accumulation capacities of heavy metals in edible part than sugarcanes. Prediction models of Cd and comprehensive accumulation factors were established for rice and sugarcane, and different soil factors affect metal accumulation in crops cultivated in different types. Due to the exposure to As and Cd through rice consumption, non-carcinogenic risks are likely to occur in Liujiang residents.

Sedimentological and geochemical characterization of DF-2 well, Onshore Western Niger Delta: Implications for provenance, tectonic history and paleo depositional conditions

The sedimentology and geochemistry of the major oxides and trace elements of DF-2 well, Onshore, Niger Delta, are presented in this study. The study is aimed at describing the sedimentological characteristics as well as using the major oxides and trace elements to investigate the provenance, tectonic history and palaeo-depositional conditions of the well. Selected samples were investigated with fused bead X-Ray Fluorescence (XRF) spectrometry to determine their major oxides and fused bead laser ablation inductively couple plasma mass spectroscopy (LA-ICP-MS) for their trace elements. Sedimentological analysis from the well shows that the lithology ranged from shaly sand, sandy shale, sandstone and shale. The results show the dominance of silicon oxide (SiO2) contents which ranges from 81.1 to 91.4 wt. % (average of 87.1 wt. %). The low average concentration of Cr<150 ppm and Ni <100 ppm, the ratios of Th/Sc, Th/Co, Th/Cr, Cr/Th, La/Sc, as well as the plots of Th/Co versus La/Sc and TiO2 versus Zr, all infer a felsic source rock. The discrimination plots of ratioK2O/Na2O against SiO2 and Log K2O/Na2O against Log SiO2/Al2O3 indicated passive continental margin. Various chemical classifications of the sediments show that the sandstone facies plotted mainly in quartzarenite, sublitharenite and Fe-rich sand domains. The samples were deposited under oxic environment based on the average values of U/Th (0.26 ppm), Ni/Co (2.79 ppm) and Cu/Zn (1.81ppm) and bivariate plot of Ni/Co versus V/Cr. However, the bivariate plot of Ni/Co versus V/ (V+Ni) specifies oxic to anoxic conditions and V/Vi + Ni ratios indicate oxic, suboxic to euxinicpalaeode positional environments for the sediments. Geochemical characterization illustrates mixed marine and terrigenous source input, deposited mainly in semi humid/humid climate. The positive values attained from ratios of Al2O3/(CaO+MgO+Na2O+K2O) infers mineralogical maturity based on stable mobile oxides content in the studied samples.
 Keywords: Felsic Rock, Quartzarenite, Litharenite, Passive Margin, Mobile Oxide, Mature Sediments.

Investigation of natural radionuclide and essential metal contents of ancient wheat einkorn (Triticum monococcum L.) grown in Turkey

Abstract Einkorn (Triticum monococcum L.) is accepted as the oldest known wheat. In this study, the natural radionuclide and essential metal contents of siyez samples collected from 21 different cultivation areas in Kastamonu province located in the Western Black Sea region of Turkey were determined by using non-destructive analytical methods. The average activity concentrations of 40K, 226Ra and 232Th measured in siyez samples using a gamma-ray spectrometry were found as 181.3 ± 4.1, 10.0 ± 0.7 and 6.1 ± 0.2 Bq kg−1, respectively. The average annual effective radiation dose that the people are exposed to due to the consumption of siyez samples was estimated as 68.2 ± 3.1 µSv y−1. The average concentrations of Cr, Mn, Fe, Co, Ni, Cu and Zn essential trace metals analyzed in einkorn samples using EDXRF spectrometry were found as 3.6 ± 0.2, 89.2 ± 1.2, 208.5 ± 62.6, 16.8 ± 0.6, 12.1 ± 0.1, 8.3 ± 0.2 and 65.3 ± 2.5 mg kg−1, respectively.

Evaluating the biotoxicity of surface water in a grassy lake in North China

The biological toxicity of aquatic ecosystems should be considered when assessing the effects of toxicity on the water environment. The aim of this study was to identify the main pollutants in the Baiyangdian (BYD) and the factors that contribute to biological toxicity. We determined various physical and chemical indicators in the surface water of the BYD, including nutrients and heavy metals, and the biological toxicity. We also explored the sources of the main pollutants and how the pollutants contributed to toxicity in the lake, using correlation analysis and an index of the biological toxicity. The results showed that total nitrogen (TN), ammoniacal nitrogen (NH4+-N), chromium (Cr), and zinc (Zn) were the main pollutants in the BYD surface water. The average concentration of Cr was 2.3 times greater than the Class V threshold, and the concentrations at about 65% of the sampling points, mainly those in the southern part of the BYD, exceeded the threshold standard. The average concentration of Zn was 1.25 times higher than the Class V threshold, with the concentrations of about 35% of the samples greater than the threshold concentration. The integrated toxicity of the surface water to luminescent bacteria ranged from 0.51% to 58%, and averaged 24.07%, which was within the range of moderate toxicity. The inhibition rates were high near Diantou (59%) and Duan (51.6%). The pollutant levels in the BYD tend to be related to the population density, with pollution mainly caused by sewage and domestic garbage, with little influence from local industries. Cr and TN were strongly correlated, but the biological toxicity was not correlated with any of the individual environmental indicators, which suggests that the toxicity in the surface water of the BYD reflected the combined effects of the environmental factors, rather than a single factor. The information from this study, about the main pollutants and the relationships between the physical and chemical properties of the surface water in the BYD, can be used to support plans for restoring the BYD.

Assessment of Anthropogenic Sources of Potentially Toxic Elements in Soil from Arable Land Using Multivariate Statistical Analysis and Random Forest Analysis

In order to study the spatial distribution and anthropogenic sources of potentially toxic elements in Xiangzhou, soil samples were collected from arable land and were analyzed for five different potentially toxic elements: Cd, Hg, As, Pb, and Cr. Inverse distance weighting (IDW) was used to study the spatial distribution of potentially toxic elements in the soil, while principal component analysis (PCA) and random forest analysis (RFA) were applied to examine the anthropogenic sources. It was shown that the combination of multiple analysis tools provides an effective way of delineating multiple potentially toxic elements from anthropogenic sources. The results showed that the average contents of Cd, Hg, and Cr in soils were lower than the background values of Hubei, whereas the average concentrations of As and Pb in soils were higher than the background values of Hubei. Through PCA, it was concluded that human activities contributed more than 60% of the As, Pb, and Cr concentrations in Xiangzhou soils, which was verified by a random forest simulation methodology. Through random forest analysis, Pb, As, and Cr in the soil were found to originate from factories and enterprises, livestock farms, mining areas, and traffic; Cd in the soil was found to originate from mining and the processing of minerals, human production and construction activities, and agricultural irrigation; and Hg in the soil was found to originate from livestock manure, mining and processing of minerals, and human industrial production. The results of this study could provide support for better management of soil pollution through prevention practices such as specific industrial governance and layout optimization.

Risk assessment and hotspots identification of heavy metals in rice: A case study in Longyan of Fujian province, China

The potential threats of heavy metals in rice have attracted increasing attention worldwide. In this study, we assessed the pollution status and health risk of rice collected from Longyan in Fujian, China. Meanwhile, we explored the spatial pattern and hotspots of those metals. The results showed that the average concentrations of Cd, Hg, As, Pb, Cr, Ni, Cu, and Zn in rice were 0.064, 0.002, 0.464, 0.072, 0.138, 0.106, 10.819, and 23.788 mg kg−1, respectively. Among them, As and Cu remarkably accumulated with the exceeding ratio of 50.30% and 55.12%, respectively. Furthermore, the values of the target hazard quotient in rice ranked as As > Cu > Zn > Cd > Pd > Ni > Hg > Cr, which As and Cu was greater than 1.0. And the carcinogenic risk values were in the order of As > Cd > Ni > Cr, which all exceeded the tolerance level (1 × 10−4). Risk assessment indicated that both children and adults were posed the non-carcinogenic and carcinogenic risk from rice intake, and As had the largest contribution rate for them. Comparison found that the spatial patterns of heavy metals distribution were consistent with the hotspots. The hotspots for As and Zn located in the western part (Changting and Wuping), Cd and Cu in the eastern part (Xinluo and Yongding), Cr and Ni were simultaneously found in the northeast (Zhangping), while Hg and Pb were mainly located in the central region (Shanghang). Overall, combining the pollution status, risk assessment, and hotspot distribution in rice, the western region (Changting and Wuping) were identified as priority areas for remediation.

Heavy Metal Contamination and Health Risk Assessment of Corn Grains from a Pb-Zn Mining Area

A total of 92 corn grain samples, around the Pb-Zn mining area in Southwest China, were collected to evaluate the contamination and health risk of heavy metals. Heavy metals including Pb, Zn, Cd, Cr, and Ni in samples were analyzed. A single factor pollution index and comprehensive pollution index were calculated to assess the quality of corn grains. The potential health risks to adults and children due to the intake of these heavy metals through consumption of crops were evaluated using the health risk index. The results showed that the average contents of Pb, Zn, Cd, Cr, and Ni in corn grains were 0.30, 23.75, 0.21, 1.33, and 1.15 mg ·kg-1, respectively, Among the metals, the content of Zn, Pb, Cd, Cr, and Ni exceeded the national food hygiene standards. The Nemero index of Pb, Cd, Cr, and Ni ranged from 4.32 to 9.07, indicating an extremely high level, whereas the contamination of Zn reached an alarming level. The assessment results of the comprehensive health risk index for the corn grains indicated that the contamination of heavy metals poses health risks to adults and children by food ingestion; moreover, the children were more sensitive to various heavy metals than the adults. Principle component analysis revealed that the first main component dominated the sources of Pb, Cd, Cr, and Ni, while the second main component, Zn, might have originated from sources different from the other heavy metals. Positive correlations were not observed between the heavy metals in corns and soils.

Contamination characteristics of heavy metals in a small-scale tanning area of southern China and their source analysis.

Tanning industry has been identified as a significant source of heavy metals; however, heavy metals contamination in farmland soil due to small-scale tanning activities remains unstudied. Here, samples from topsoil, profile soil, water and sediments in the vicinity of a small-scale tanning area in Nanning, Guangxi Zhuang Autonomous Region, southern China, were collected to explore the contamination characteristics and source apportionment of Cd, Cr, Hg, As, Cu, Pb, Ni and Zn. The results show that the farmland soil was mainly contaminated by Cr and its content was 33.40-3830.00mgkg-1. The highest level of Cr, Cd and Hg was above their thresholds, while the average contents of Cd, Cr, Pb and Hg exceeded the corresponding background levels. Moreover, enrichment of Cr in soil profiles and stream sediments were also observed, whose concentrations varied from 11.50 to 2590.00mgkg-1 and 738.00 to 11,200.00mgkg-1, respectively. Concentrations of Cr in top soils and soil profiles from farmland surrounding the stream were significantly higher than those from other areas, and the soils surrounding the stream were moderately to heavily polluted. The multivariate statistical analysis indicated that the heavy metals originated from traffic (Cu, Ni, Zn, Hg, and Pb), agriculture (Cr and Cd) and nature (As). Source apportionment with PMF model results showed that the relative contribution rates of heavy metals by traffic, tanning, agriculture, other industrial activities and natural sources were 16.00%, 18.88%, 20.88%, 22.04% and 22.20%, respectively. These findings indicate that small-scale tanning activities could also lead to heavy metal accumulation in the surrounding environment, which requires decision-makers to pay more attention and to develop effective remediation procedures.

Pollution assessment and source analysis of heavy metals in acidic farmland of the karst region in southern China—A case study of Quanzhou County

This research focused on the concentrations, pollution assessment, and source identification of eight heavy metals in acidic farmland of the karst region in China. Two hundred eighty-eight soil samples (0–20 cm) were collected from farmland in the karst region of Quanzhou County, Guangxi Province and analysed using multiple methods. The results revealed that the average concentrations of Cd, Pb, Zn, Cr, As, and Hg were higher than the soil background values of China, but lower than the soil environmental quality risk control standards for soil contamination of agricultural land, except for Cd. Based on the spatial distribution and the geoaccumulation index (Igeo), the order of the Igeo values was Cd > Pb > NiZn > Cr > As > Hg > Cu. There was moderate pollution of Cd, slight pollution of Pb and As, and no pollution of Ni, Zn, Cr, Hg, and Cu. Multivariate statistical analyses showed that the accumulation of As, Cr, and Ni in the soils was attributed to weathering of parent carbonate rocks. The accumulation of Cu, Pb, Zn, and Hg was mainly affected by industrial and mining activities. However, Cd mainly originated from parent rock materials and terrain with high natural background levels, followed by agricultural activities (fertilisers). Considering the impacts of these potentially toxic elements on public health, the results of this study are essential for taking preventive actions for environmental protection and sustainable development in the region.

Distribution, contamination, toxicity, and potential risk assessment of toxic metals in media from Arufu Pb–Zn–F mining area, northeast Nigeria

Toxic metals exuding from mining remain a challenge to the environment and human health. This study investigated the distribution, contamination, toxicity, and potential risks of toxic metals in rocks, soils, sediments, and tailings from a typical Pb–Zn–F mineralization zone in Nigeria. In this study, 64 samples which include soils, stream sediments, mine tailings, rocks, and plants were collected. All samples were prepared in the laboratory using acceptable international procedures. Metals in media were chemically digested and analyzed using inductively coupled plasma-mass spectrometer. The concentration of metals in media was above their concentrations in background samples. The average concentration of As, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn in soils of the area is 0.90 µg/g, 0.10 µg/g, 7.10 µg/g, 27.18 mg/kg, 8.90 mg/kg, 0.10 mg/kg, 8.10 mg/kg, 959.30 mg/kg, and 109.30 mg/kg respectively while their concentration in tailings is 5.17 mg/kg, 1.74 mg/kg, 23.40 mg/kg, 38.40 mg/kg, 19.60 mg/kg, 17.00 mg/kg, 1275.00 mg/kg, and 359.80 mg/kg, respectively. Pollution load index (PLI) values for metals are >1 indicating severe pollution in the area. Bioaccumulation and translocation factors were >1 and showed that metals were mobilized from the media to different parts of plants. Risk index (RI) showed that heavy metals posed strong to extreme ecological risks. The carcinogenic risk (CR) is >0.4 and non-CR is >1 for adults and children which implies exposure to high carcinogenic and non-CRs. We suggest that complete remediation of contaminated media be carried out in the area.