Level Of Heavy Metal Pollution Research Articles

Background levels of heavy metals in the water of Khadzhibey estuary

In the Odesa region, heavy metal contamination of fishery water bodies is a pressing problem. The accumulation of heavy metals in fish depends on the physiological and biochemical activity of the organism and the physical and chemical parameters of the water body. Most heavy metals enter the fish's body through the gills, skin, and digestive organs. Copper, zinc, and plumbum accumulate in the skin, gills, and liver, while cadmium and mercury accumulate in the kidneys. The level of heavy metal pollution in the water of the Khadzhibey estuary was measured and determined in 2022–2023. The following methods were used to determine the content of heavy metals in water: atomic emission spectroscopy using an EMAS-200 CCD instrument to determine cadmium, copper, zinc, and plumbum; cold vapor atomic absorption spectroscopy using the “Julia-2M” method to determine the content of mercury. Toxicological studies of water were carried out in the water hygiene and ecology laboratory of the Ukrainian Research Institute of Transport Medicine and at the Department of Veterinary Hygiene, Sanitation, and Expertise of Odesa State Agrarian University. The study found that the content of heavy metals in the water of the Khadzhibey estuary is not constant and fluctuates depending on the season. The maximum levels of heavy metals are observed in summer (plumbum and cadmium) and autumn (zinc, copper and mercury). It was found that cadmium, plumbum, copper, and mercury content does not exceed the maximum permissible levels for marine fisheries. The zinc content in the water of the Khadzhibey estuary exceeds the maximum permitted concentration by 2.65%. The zinc content in the studied water samples is a stress factor affecting the meat quality of common carp (Cyprinus carpio) and round goby (Neogobius melanostomus).

Surface water-groundwater interactions drive the spatial variability of dissolved heavy metals and interfacial fluxes in mangrove intertidal zones

The intertidal aquifer is a crucial area that significantly influences the transport of heavy metals and the health of coastal environment. In this study, we used a 3-dimensional sampling method to analyze the spatial variability of heavy metals in the groundwater of the mangrove intertidal zone in China. The pollution level of heavy metals and their release processes into coastal waters through groundwater discharge were also explored. Our findings revealed high spatial heterogeneity of heavy metals occurred along the cross-shore, parallel-shore, and depth directions. Specifically, heavy metals exhibited inconsistent variation trends between the seawater infiltrated zone and groundwater discharge zone along the cross-shore direction. Fe, Cr, Cu, Zn, and Pb exhibited a similar variation trend along the cross-shore direction, but were opposite to that of Hg and As. In addition, most heavy metals showed higher concentrations in mangrove groundwater compared to inland pond water and coastal seawater, indicating that mangrove intertidal zone played a crucial role in sequestering heavy metals. The spatial variability of heavy metals can be attributed to different exchange types and magnitudes between the surface water and groundwater, as well as the complex biogeochemical reactions. Our study also identified a slight pollution level of Zn and Hg, and high groundwater discharge-derived fluxes of Hg and As compared with other study sites in the world. In addition, this study highlights the importance of considering different groundwater end-member, especially for redox sensitive heavy metals, when determining groundwater discharge-derived fluxes into the surface water in mangrove intertidal zone.

Spatial Distribution, Risk Assessment and Sources of Heavy Metals in Roadside Soils Exposed to the Zhengzhou-Kaifeng Intercity Railway in Huanghuai Plain, China

ABSTRACT Heavy metal accumulation in soil can seriously harm human health, and it is necessary to identify the accumulation status and access the potential risks for local pollution control and sustainable economic development. This study evaluated the pollution level, spatial distribution, potential risk and sources of soil heavy metals along the Zhengzhou-Kaifeng intercity railway and compared pollution characteristics in north side soils with south side soils of the railway. A total of 260 soil samples were collected from a section along the railway. In practice, only the average Zn and Pb contents in soils were slightly higher than their corresponding risk screening values. The heavy metal enrichment in the north side soils was marginally lower than that in the south side soils. The spatial distribution of soil heavy metals except Pb could be mainly influenced by the different land use types. The geoaccumulation index and potential ecological risk of a single heavy metal indicated that Cd was the major contaminant with moderate pollution and high ecological risks in the south side soils and none to moderate pollution and moderate ecological risks in the north side soils. However, the mean multimetal potential ecological risk values suggested that the north side soils were at low ecological risks and the south side soils were at moderate ecological risks. The comprehensive non-carcinogenic risks and total carcinogenic risks for adults were low and acceptable, respectively. Pearson correlation analysis, PCA, and APCS-MLR analyses identified that the contributions of natural sources, mixed sources of industrial and traffic activities, agricultural activities, and other sources were 57.49%, 21.44%, 12.67% and 8.40%, respectively, and the major soil pollution Cd was mainly related to mixed sources of industrial and traffic activities. Therefore, continuous soil heavy metal monitoring is essential to elucidate the long-term railway operation effect on soil heavy metal accumulation.

Pollution Level and Sources of Heavy Metals in Indoor Dust from College of Science, University of Anbar Campus, Iraq

This research aims to evaluate the level of heavy metal pollution [Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Lead (Pb) and Zinc (Zn)] in indoor dust samples taken from the College of Science at the University of Anbar in Iraq and their likely sources. Atomic absorption spectrophotometer was used to evaluate the dust samples that were taken from 39 locations (classrooms, offices, and laboratories). Zn > Pb > Cr > Co > Cu > Cd was the order in which the heavy metal concentrations were found. The findings showed that all metal concentrations at various times exceeded background values. Using the geo-accumulation index (Igeo) and contamination (CF), the pollution level was calculated. The values of Igeo and CF indicate that the indoor dust in the College of Science is heavily polluted with Pb and Cd and is unpolluted to moderate polluted with the other metals. Pb, Cd, and Zn may be released from anthropogenic sources, while Co, Cr, and Cu may come from a combination of sources, according to the coefficient of variation (CV) comparison of the heavy metal concentrations with background values, Pearson’s correlation, cluster analysis (CA), and principle component analysis (PCA).

Heavy metals assessment of farmland soil in Bagega mining community, Zamfara State, Northwestern Nigeria

The present study was conducted to examine the level of heavy metals pollution of farmlandsoil at Bagega community, Anka Zamfara State as a result of artisanal and illegal mining activities going on in the community. Soil samples were collected from farmland soil at thedepth of 15cm, acid digestion was carried out and the solution was subjected to Atomic Absorption Spectrophotometer model Varian AA240FS for the metal analysis. The level of soil contamination were assessed by Geo-accumulation Index (Igeo) and Pollution Load Index (PLI). The Geo-accumulation studies show that the soil was moderately polluted by Pb (1.21 mg/kg), Fe (0.9 mg/kg), Zn (0.91 mg/kg) and Cu (1.46 mg/kg). The Pollution Load Index result shows that farmland soil was polluted, with PLI value of 2.1. Also, the geochemical distribution of the metals in the soil samples was revealed by sequential extraction procedures which show that 90 % of the metal concentrations were found in the residual fractions. This signified high level of heavy metals contamination of the farmland soil is associated with the anthropogenic activities such as the mining activities going on in the community.

Characteristics and risk assessment of atmospheric PM<sub>2.5</sub> heavy metals pollution near coal gangue sites in Huaibei, China

To study the level of atmospheric PM<sub>2.5</sub> and its heavy metal pollution near the coal gangue mountain, this study analyzed the content of seven heavy metals (Zn, Pb, Cu, Cd, Hg, Ni, Cr) and As through the PM<sub>2.5</sub> samples from the vicinity of a large-scale coal gangue filed of Tongting coal mine in Huaibei, and evaluated the level of pollution, sources, and health effects. The results showed that during the sampling period, the average concentration of PM<sub>2.5</sub> near the coal gangue field was 169.83 μg·m<sup>-3</sup>, which was 2.26 times that of the national air quality level Ⅱ daily standard. The coal gangue field may be an important source of air pollution, with the degree of heavy metal and arsenic pollution in the order of Cd, Pb, Zn, Hg (extremely heavy pollution) > As, Cu (medium pollution) > Ni, Cr (light pollution) and coal gangue dust and mining dust contributed more. This study provides data for atmospheric particulate matter and heavy metal and arsenic pollution levels near coal gangue fields and provides a theoretical basis for air pollution prevention and control near coal gangue hills.

Source Appointment and Assessment of Heavy Metal Pollution in Surface Dust in the Main District Bus Stops of Tianshui City

In this study, a PMF model was used to identify the sources and pollution level of heavy metals in the surface dust of a bus station. On the basis of the traditional heavy metal pollution evaluation methods, the Hakanson toxicity response coefficient was used to modify the traditional weight. The matter-element extension theory was introduced to reflect the toxicological properties and hazard degree of the heavy metals, and the matter-element extension model was established to evaluate the pollution level of heavy metals in the surface dust of the study area. The results were compared with Igeo, PN, and RI. ① Except for Co and V, the other heavy metals were higher than the Gansu soil background values by 1.29-9.30 times. The points of Cu and Pb exceeded the rate by 100%, and Cr, Ni, and As exceeded the rate by 96.15%, 94.23%, and 96.15%, respectively. ② PMF showed that source 1 was a natural source, and its contribution rate to V was 32.12%. Source 2 was natural-traffic pollution sources, contributing 51.50% and 33.37% to Cu and Co, respectively. Source 3 was a construction waste pollution source, with contribution rates of 45.06% and 44.70% for Cr and Ni, respectively, and source 4 was a coal-traffic mixed source, with contribution rates of 49.89% and 75.25% for As and Pb, respectively. ③ The matter-element evaluation results showed that the surface dust of the bus stops was mainly class IV (moderately polluted), and 13% of sample points were still clean, 37% were moderately polluted, and 25% were slightly and heavily polluted. The results of this method were quite different from the PN results and were more consistent with the RI results, indicating that its evaluation results were more sensitive and can be used for heavy metal pollution assessment.

Contamination Characteristics and Source Apportionment of Soil Heavy Metals in an Abandoned Pyrite Mining Area of Tongling City, China

To investigate the impact of pyrite mining on the heavy metal pollution in the surrounding soil in Tongling City, 50 surface soil and sediment samples were collected from mining fields, farmland, forests, villages, and the river. The contents of Zn, Cr, Cu, Pb, Ni, Cd, and As in soils and sediments were analyzed. Then, the spatial distribution characteristics of heavy metals in soil were analyzed, and the degree of heavy metal pollution and potential ecological risk level were assessed. Finally, the sources of soil heavy metal pollution were identified. In general, the soil in the study area was weakly acidic (average pH=6.32), and the contents of other heavy metals except Ni exceeded the background values of the soil in Tongling City. Moreover, Ni and Cd were enriched in the river sediments. According to the Nemerow pollution index, Pb and As reached heavy pollution levels, Cu and Cd reached moderate pollution levels, and other elements belonged to light or non-pollution levels. The comprehensive pollution index of different land types was ranked in the order of mining field > river > forest > farmland > village. Mining fields and the river were heavily polluted, forest land was moderately polluted, and farmland and villages were mainly mildly polluted. Pb, As, and Cd belonged to the medium ecological risk category. The contribution rates of the potential ecological risk index were 33.27%, 27.39%, and 20.22%, which were much higher than the other four elements. The ranking results of the potential ecological risk index of different land types was the same as that of the comprehensive pollution index. Mining fields and the river were at a high-risk level, forest land reached moderate risk, and the rest were at a slight risk level. The consistent results of correlation analysis, principal component analysis (PCA), and positive definite matrix factor analysis (PMF) indicated that Zn, Cu, Pb, Cd, and As were mainly derived from pyrite mining activities, Cr mainly came from the parent material and agricultural production, and Ni was mainly affected by soil-forming parent material and pyrite mining activities.

Level of Heavy Metals in Fish and Associated Human Health Risk From the Omo Delta in Southern Ethiopia: A First-Hand Report.

This study was the first to investigate the levels of heavy metals in commercially important fish species (Lates niloticus and Oreochromis niloticus) and the human health risk in Southern Ethiopia. Sixty fish samples were collected from the Omo delta. The target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR) were used to estimate the human health risks. The mean levels of heavy metals detected in the liver and muscle of Lates niloticus generally occurred in the order of Fe> Zn > Pb > Cu >Mn> Cr > Co > Ni and Fe > Pb > Zn >Mn > Cu > Co > Cr >Ni, respectively. Similarly, the mean levels of iron in the muscle and liver tissues of Oreochromis niloticus were in the order of Fe > Pb > Zn >Mn> Cu > Cr > Co > Ni and Pb > Fe > Zn >Mn> Co > Cu > Ni, respectively. The THQs in the muscle of L. niloticus and O. niloticus decreased in the order Pb > Cr > Cu >Mn> Co > Zn > Fe> Ni and Pb >Mn> Co > Cu > Zn > Ni> Fe respectively. Pb had the highest THQ value in L. niloticus and O. niloticus, which were 0.61 and 0.409, respectively in adult. Similarly, Pb had noted that, L. niloticus and O. niloticus had the highest THQ values, at 0.87 and 0.58, respectively in children. The HI values due to consumption of L. niloticus muscle were 0.668 for adults and 0.942 for children. The mean concentrations of Pb and Cr in the tissues of L. niloticus and O. niloticus were above the FAO/WHO permissible limits. Consequently, investigating heavy metal pollution levels in fish and human health risks from the Omo delta is imperative for addressing environmental and public health concerns.

ASSESSMENT OF CONTAMINATION LEVEL AND SOURCE APPORTIONMENT OF HEAVY METALS IN SERAYU RIVER WATER, INDONESIA

Diverse community activities along the river can alter water quality, particularly heavy metal pollution, which can negatively affect public health. This study examines the contamination and distribution of heavy metal sources in the Serayu River, one of the longest and largest rivers in Central Java Province in Indonesia. Along the Serayu River, water samples were obtained from 18 distinct sampling points. Heavy metals content in water samples was measured for lead, cadmium, chromium, nickel, arsenic, cobalt, iron and manganese. Pb, Cr and Ni Concentrations have surpassed government rule No. 22 of 2021 regarding quality criteria in several locations. The contamination factor (CF) determines the level of heavy metal pollution in the Serayu River. The average value of CF, from highest to lowest, is as follows: Pb (2.03); Ni (0.24); Cr (0.24); Fe (0.21); Mn (0.10); Co (0.04); Cd (0.04); As (0.02). The modified degree of contamination (MCD) suggests that the bulk of river water falls into moderate contamination. Agricultural practices in the upper reaches of the Serayu River are regarded as the primary source of surpassing the quality level. Multivariate statistical analyses, namely principal component analysis (PCA), pearson correlation matrix and cluster analysis (CA), revealed that most heavy metals originated from various human activities. Pb, Cr and Ni were primarily derived from agricultural activities, whereas Cd, Co and Mn were primarily derived from industrial, agricultural, settlements and tourism. As and Fe are primarily derived from mining. The alternative recommendation for contamination recovery is the application of biochar which is economically affordable material to be applied in the river.

Assessing the ecological and health risks associated with heavy metal pollution levels in sediments of Big Giftun and Abu Minqar Islands, East Hurghada, Red Sea, Egypt

This study assessed pollution levels, ecological and health risk, and spatial distribution of eight heavy metals in sediments of Big Giftun and Abu Minqar Islands, Red Sea, Egypt. Iron (Fe) and manganese (Mn) had the highest contents in both island sediments, while cobalt (Co) in Big Giftun and cadmium (Cd) in Abu Mingar had the lowest values. The obtained PCA data exhibited positively significant loadings of Cd, Co, copper (Cu), nickel (Ni), and zinc (Zn) with 51.03 % of data variance in Big Giftun, and lead (Pb), Cu, Mn, Ni, Zn, and Fe (37.7 %) in Abu Minqar sediments. The contamination factor (CF) showed low contamination for all metals, except cadmium; Cd (moderate). The geo-accumulation index (Igeo) values showed uncontaminated (Cd, Co), moderately (Cu), extremely contaminated (Fe, Mn) (Igeo > 5) in Big Giftun, and uncontaminated (Cd), moderately to strongly contaminated (Cu, Ni), and extremely contaminated (Fe, Mn, and Zn) in Abu Minqar sediments. The pollution load index (PLI) values indicated baseline level of contamination (PLI <1), and degree of contamination (DC) indicated low degree of contamination (DC < n) in all sediments. Nemerow pollution index (NPI) showed unpolluted sediments in Abu Minqar (NPI ≤1) and slight pollution (1 < NPI ≤2) in Big Giftun. Cd showed moderate potential ecological risk (40 ≤ Eri < 80) in Big Giftun sediments. Potential ecological risk index (PERI) indicated low risk sediments (PERI <150). Mean effects range median quotient (MERMQ) indicated low-priority risk of toxicity (MERMQ ≤0.1), and toxic risk index (TRI) showed no toxic risk in all sediments (TRI <5). The modified hazard quotient (mHQ) indicated very low severity of contamination (mHQ <0.5). The hazard quotient (HQ) levels of all metals were below the safe value (HQ <1). The hazard index (HI) levels indicated that no chronic risks occur (HI <1). The total cancer risk (TCR) for all metals were below the safe level (1 × 10−4) of the United States Environmental Protection Agency (U.S. EPA) guidelines.

Uncertainty Evaluation of Soil Heavy Metal(loid) Pollution and Health Risk in Hunan Province: A Geographic Detector with Monte Carlo Simulation.

Research on soil heavy metal(loid) pollution and health risk assessment is extensive, but a notable gap exists in systematically examining uncertainty in this process. We employ the Nemerow index, the health risk assessment model, and the geographic detector model (GDM) to analyze soil heavy metal(loid) pollution, assess health risks, and identify driving factors in Hunan Province, China. Furthermore, the Monte Carlo simulation (MCS) method is utilized to quantitatively evaluate the uncertainties associated with the sampling point positions, model parameters, and classification boundaries of the driving factors in these processes. The experimental findings reveal the following key insights: (1) Regions with high levels of heavy metal(loid) pollution, accompanied by low uncertainty, are identified in Chenzhou and Hengyang Cities in Hunan Province. (2) Arsenic (As) and chromium (Cr) are identified as the primary contributors to health risks. (3) The GDM results highlight strong nonlinear enhanced interactions among lithology and other factors. (4) The input GDM factors, such as temperature, river distance, and gross domestic product (GDP), show high uncertainty on the influencing degree of soil heavy metal(loid) pollution. This study thoroughly assesses high heavy metal(loid) pollution in Hunan Province, China, emphasizing uncertainty and offering a scientific foundation for land management and pollution remediation.

Assessment of some heavy metal content in sediments of a mangrove swamp, niger delta, nigeria using applicable ecological risk indices

Sediments can act as pollutant sinks and a source of pollution in aquatic environments. The surface sediments of the Isaka–Bundu tidal swamp, Niger Delta was assessed for heavy metal content using standard methods and assessment indices. The study was carried out in three stations between January and June 2022. Five heavy metals (lead, copper, cadmium, nickel and zinc) were evaluated while eight assessment indices (Contamination Factor - CF, degree of contamination - DC, Ecological Risk - Er, Potential Ecological Risk - PERI, Pollution Load Index - PLI, Enrichment Factor - EF, Geo-accumulation Index - Igeo and Quantification of Contamination -QoC) were applied. Results showed that cadmium and copper exceeded permissible limits while lead, zinc and nickel were within limits. Stations 1 and 3 recorded significantly higher values indicating anthropogenic influence. The dominant anthropogenic activities observed in the area include maritime and dockyard activities and artisanal crude oil refinery. The assessment indices showed that the sediments were at various levels of heavy metal pollution mainly influenced by copper and cadmium viz: CF: Cu (considerable degree) and Cd (very high degree), DC (very high degree), Er: Cd (high ecological risk) and Cu (very high ecological risk), PERI (significant high ecological risk), PLI (very high level pollution), EF: Pb, Zn, Cu (Station 1) and all Cd (extremely high enrichment), Igeo: Cd (extremely polluted) and QoC: Cu and Cd (anthropogenic source). The sediments were highly polluted with toxic metals, which is detrimental to humans and aquatic biota.Keywords: Heavy metal; Indices; Mangrove; Niger Delta; Sediment.

Characteristics and risk assessment of microplastic mediated heavy metal transport in black clam Villorita cyprinoides from a Ramsar wetland of South India

The synergetic and interactive effects of microplastics (MPs) as potential carriers of pollutants and pathogens have a manifold impact on human health and aquatic biota. The present study delineates the role of MPs in transporting heavy metals to the black clam, Villorita cyrpinoides of Vembanad Lake in South India. MPs in water (3.41 ± 1.87 items/L), sediment (154.6 ± 45.4 items/kg) and within clams (0.87 ± 0.34 items/g tissue) showed considerable variation based on their physical and chemical characteristics, which in turn reflected its differential potential to carry heavy metals. Though the levels of heavy metals (Al, Fe, Mn, Zn, Cr, Pb) within the clam and those carried by MPs were less than the hazardous limits, the concentration of Cd within the clam and MP was found to have a positive correlation. Though the present levels of heavy metal pollution in the lake do not pose a direct threat to humans, anthropogenic interventions and reduced water flow have turned the lower reaches of the lake into a sink of heavy metals. Hence with MP concentration increasing it is worth investigating how their future interactions with heavy metals and other pollutants would pose a risk to living organisms.

Will different land uses affect heavy metal pollution in soils of roadside trees? An empirical study from Shanghai.

Heavy metal pollution in roadside soil may harm humans, animals, plants, and local ecosystems. This study aimed to explore the sources and potential ecological risks of heavy metals in soils of roadside trees under different land uses, using soil samples collected from 136 roads across 16 administrative districts in Shanghai. The contents, pollution characteristics, potential ecological risks, and sources of seven heavy metals were analyzed, including Cr, Ni, Cd, Pb, As, Cu, and Zn. Results showed that (1) land use patterns affected the heavy metal contents, with industrial and construction areas showing higher contents while agricultural and forestry areas lower; (2) the ranking of heavy metal pollution levels was Cd > As > Pb > Cu > Ni > Cr > Zn. Cd exhibited the highest potential ecological risk, falling within the moderate to considerable potential ecological risk interval; (3) the sources of Cu, Zn, Cr, Ni, Cd, and Pb were associated with traffic emissions, whereas As had independent other sources and Pb in industrial and construction areas was also influenced by industrial emissions. These results provide valuable references on the control of heavy metal pollutants and the management of land uses in megacities.

Analysis of Pollution Levels of Heavy Metals of Lead (Pb) And Copper (Cu) In Freshwater Fish In Lake Toba Water

Community activities in an effort to utilize the wealth of Lake Toba water resources can produce heavy metals in the waters and affect the life of biota that interact directly with the waters, especially freshwater fish. This research aims to analyzez the concentration of heavy metals contained in freshwater fish in the waters of Lake Toba. The research was conducted in August-September 2022 in the waters of Lake Toba, Simalungun Regency, North Sumatra Province. The sampling process used purposive sampling method. Data analysis was carried out descriptively by looking at the results of measurements of several water parameters and the results of sample tests in the laboratory by comparing the quality standards. The results of the concentration of heavy metals contained in freshwater fish for Pb ranged from 0.0386 to 0.0700 ppm while for Cu metal ranged from 0.0059 to 0.0325 ppm. The results of the calculation of the value of the bioconcentration factor (BCF) of freshwater fish on Pb metal ranged from 0.401 to 0.721 while the value of the bioconcentration factor (BCF) of Cu metal ranged from 2.347 to 8.325. Analysis of the effect of the relationship between heavy metal content in plankton on environmental parameters processed using SPSS 16 software, showed that there was a fairly close relationship between heavy metals Pb and Cu in freshwater fish which was influenced by water parameters in Lake Toba. Environmental parameters that affect the content of heavy metals in freshwater fish include temperature, current velocity, salinity, dissolved oxygen and pH.

Assessment of heavy metal pollution in surface water of Bangladesh

Industrial discharge of heavy metals severely deteriorates surface water quality in many parts of the world, particularly in lower-middle-income countries like Bangladesh. This study collected published data from 30 different surface water bodies in Bangladesh, including rivers, lakes, freshwater wetlands (Haors), and river estuaries, on mean concentrations of 12 heavy metals (Cd, Pb, Cr, Hg, Zn, Cu, Ni, Al, Fe, Mn, As, and Co) in surface water bodies from 2010 to 2022. The study aimed to explore the pollution source and levels of heavy metals in the surface water of Bangladesh. The water quality status and correlations between variables were assessed using the heavy metal pollution index (HPI), heavy metal evaluation index (HEI), and principal component analysis (PCA). The analysis results showed that the average heavy metal concentrations in the surface water of Bangladesh were in the order of Fe>Al>Mn>Cr>Zn>Cu>As>Ni>Pb>Co>Cd>Hg in the range of 3.98 ppm to 0.004 ppm. It also showed that Dhaka, Chittagong, Mymensingh divisions, and Bogra city of Rajshahi division are the most polluted areas of Bangladesh in terms of heavy metal concentration, whereas Khulna and Sylhet divisions are moderately polluted. The results showed that about 83.3 % of water bodies have HPI values greater than 100, which is considered unsafe for consumption. However, the HEI analysis revealed that about 46.7 % of water bodies were in the high pollution category (HEI > 20). The correlation matrix of heavy metals illustrated strong positive linear relationships between Cr and Co, Cu and As, Cu and Cd, and As and Cd. The principal component analysis suggested that the most contributing sources of pollution in the studied area are related to different anthropogenic activities, such as municipal waste and industrial effluent discharge, including tanneries, textile and dyeing industries, shipbreaking yards, and gas production plants, as well as agricultural runoff.

Soil contamination, pollution indices, and ecological risk in agricultural areas of important mining region of Türkiye

ABSTRACT Heavy metals accumulate mostly in soil in nature, and heavy metal pollution is becoming a serious concern. This study aimed to determine the pollution level and possible sources of heavy metals in the agricultural areas in the Emet district of Kütahya, where a significant boron mine is located worldwide. 64 soil samples were taken from Emet district of Kütahya, Türkiye in 2016, and Cr, Co, Fe, Ni, Cu, Zn and Pb analysed. Heavy metal pollution was determined using the Enrichment Factor (Ef), Geoaccumulation Index (Igeo), Contamination Factor (Cf), and Ecological Risk Factor (Er), Pollution Load Index (PLI), and Potential Ecological Risk Index (RI). According to the pollution index Ef, the study area is moderately enriched in terms of Pb (4.18) and Zn (2.17), while in terms of Cf, the study area is moderately polluted in terms of Pb (2.13) and Zn (1.02). Moreover, the PLI (2.67) index shows that soils are under multiple heavy metal pollution. According to Pearson correlation analysis and principal component analysis, the source of Pb and Zn in the study area is anthropogenic. However, no heavy metal pollution caused by boron mine was found in the study area.

Differences among active toluene-degrading microbial communities in farmland soils with different levels of heavy metal pollution.

Heavy metals can severely influence the mineralisation of organic pollutants in a compound-polluted environment. However, to date, no study has focused on the effects of heavy metals on the active organic pollutant-degrading microbial communities to understand the bioremediation mechanism. In this study, toluene was used as the model organic pollutant to explore the effects of soils with different levels of heavy metal pollution on organic contaminant degradation in the same area via stable isotope probing (SIP) and 16S rRNA high-throughput sequencing. Heavy metals can seriously affect toluene biodegradation and regulate the abundance and diversity of microbial communities. SIP revealed a drastic difference in the community structure of active toluene degraders between the unpolluted and heavy metal-polluted soils. All SIP-identified degraders were assigned to nine bacterial classes, among which Alphaproteobacteria, Gammaproteobacteria, and Bacilli were shared by both treatments. Among all active degraders, Nitrospira, Nocardioides, Conexibacteraceae, and Singulisphaera were linked to toluene biodegradation for the first time. Notably, the type of active degrader and microbial diversity were strongly related to biodegradation efficiency, indicating their key role in toluene biodegradation. Overall, heavy metals can affect the microbial diversity and alter the functional microbial communities in soil, thereby influencing the removal efficiency of organic contaminants. Our findings provide novel insights into the biodegradation mechanism of organic pollutants in heavy metal-polluted soils and highlight the biodiversity of microbes involved in toluene biodegradation in compound-polluted environments.

Components of sludge from municipal wastewater treatment plants and its evaluation for land application in JiUJiang city of China

Municipal sewage sludge has a potential for widespread application on land, but the implementation of new standards for the agricultural use of sludge in China support a cautious approach. The organic matter, nutrients, and heavy metals in sewage sludge from four municipal wastewater treatment plants in Jiujiang City of China were continuously monitored. The feasibility for its land use was analyzed from three aspects such as sludge nutrients, heavy metal pollution levels, and potential ecological risks in soil. The average content of Cd, Cu, Zn, Cr, Ni, Pb, Hg and As in the sludge of Jiujiang City are 1.85, 305.25, 764.48, 170.57, 42.45, 42.27, 0.59, 28.79 mg∙kg-1, which are less than or close to mean value of heavy metals in China (except As), and all meet the minimum standards of heavy metal content in the sludge according to Chinese Quality of sludge from municipal wastewater treatment plant (GB24188-2009). The maximum content of Cu, Zn, Cr, and As exceed the control standards of pollutants in sludge for agricultural use, and the maximum value of Cu and Cr are close to the limit of landscaping standards. The average contents of organic matter, total nitrogen, total phosphorus, total potassium, and total nutrients in sludge are 385.16, 34.14, 11.05, 7.87, 53.06 g∙kg-1, respectively. The organic matter content meets the limit value (no less than 200 g∙kg-1) of Chinese Control standards of pollutants in sludge for agricultural use (GB 4284-2018), and the total nutrients content meets certain content limit (no less than 40 g∙kg-1) of total nutrients in China’s organic fertilizer. The single-factor pollution index and Nemerow’s synthetic pollution index methods were used to assess the pollution of heavy metals. The heavy metal pollution indexes (PI) are in descending order: Cd &gt; Cu &gt; Zn &gt; Cr &gt; As &gt; Ni &gt; Pb &gt; Hg. The PI shows that Cd and Cu are in strong pollution level, Zn is in moderate pollution level, and As, Ni, Pb, Hg are in absolute safe level. The potential ecological risk levels of heavy metal are ranked in the following order: Cd&gt; Cu&gt; As&gt; Ni&gt; Zn&gt; Cr &gt; Pb. The monomial potential ecological risk coefficients reveal that Cd is in extremely strong ecological risk, Cu is in medium ecological risk and other heavy metals are in slight ecological risk. The results indicate that Cd and Cu are the main contributors to the pollution and potential ecological risks of heavy metals in soil, to which more attention should be paid during sludge disposal. Being rich in organic matter and inorganic plant nutrients，sewage sludge in Jiujiang City may be widely used on soil, but availability of potential toxic metals exceeding the limit value often restricts its uses. Before being harmlessly treated, the sludge in Jiujiang City should not be used on agricultural land and may be applied with highly caution on landscaping and land improvement, but it can be used as cover materials for co-landfilling.