Trace elements in different land use soils of Bangladesh and potential ecological risk

WITHDRAWN: Trace metals translocation from soil to plants: Health risk assessment via consumption of vegetables in the urban sprawl of a developing country

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Bioavailability and health risk of pollutants around a controlled landfill in Morocco: Synergistic effects of landfilling and intensive agriculture

Toxic contamination of agricultural soils by trace metal(oid)s can pose detrimental effects on human health and agroecological systems. In this view, the current research explored total and available metal(oid)s in surface soils and assessed the associated hazards using pollution indices, PMF modeling, PCA, and Montecarlo probabilistic human risk assessment with 10,000 repetitions. The mean concentrations of Cd, Pb, As, Cr, Ni, Cu, Zn, and Fe were 0.89, 24.86, 1.81, 19.10, 25.44, 7.98, 49.12 and 6183.32 mg kg-1 dry weight, respectively. These findings highlighted that the concentration of pollutants exceeded the values measured in the geochemical background. Soil enrichment by heavy metal (oid)s was confirmed by analyzing available fractions using DTPA ,CaCl2 and enrichment factor (EF). Additionally, pollution indicators (Igeo, PLI, and PERI) displayed significant contamination levels, with a higher ecological risk. Matrix Factorization (PMF) receptor and multivariate statistical analysis reflected that anthropogenic activities, particularly landfilling and agricultural practices were the main causes of the contamination. Furthermore, probabilistic and deterministic human risk assessments showed that carcinogenic risks exceeded the threshold values (10-4) set by the USEPA. Consequently, it is crucial to implement continuous monitoring and supervision of landfill sites to prevent additional pollution. These measures should be integrated into the management plans for waste management.

The effects of pollution by multiple metals derived from long-term smelting activities on soil mite communities in arable soils under different land use types in East China

Soil pollution represents a threat to soil biodiversity and to soil and human health. However, many ecotoxicological issues, such as the impact of heavy metal pollution on the soil mite community and its spatial distribution in areas with complex environmental factors, are not fully understood. Here, an investigation was conducted in an arable area (about 11 km²) enclosed by surrounding mountains. The study area was contaminated with potentially toxic metals derived from copper smelting that was functioning for over 10 years. The area comprised four land use types: woodlands, dry fields, paddy fields, and wastelands, and was divided into 141 study sites each with an area of 6.25 ha. The soil metal (Cu, Zn, Pb, and Cd) contents, pH, and organic matter were determined and their distributions were established. Furthermore, soil mite (Acari) community properties (species richness, individual abundance, and Shannon-Wiener diversity index) were determined, and the distributions of total species number and abundance were ascertained. Soil metal pollution strongly reduced soil mite community, but the effects depended on mite groups or species and their sensitivity to different metals as well as land use types. CANOCO analysis revealed that the order Oribatida was more highly correlated with soil metal contents, whereas the other three orders responded to soil metal contents depending on land use types, mite properties, or metals. SADIE method indicated that the coordinate relationship between mite species number and metal concentration was more negative (4-25% of the study sites) than positive (4-12%). The metal pollution levels in the soil were evaluated by single and integrated pollution and ecological risk indices.

Receptor model-based sources and risks appraisal of potentially toxic elements in the urban soils of Bangladesh

Rapid urbanization and industrial development have prompted potentially toxic elements (PTEs) in urban soil in Bangladesh, which is a great concern for ecological and public health matters. The present study explored the receptor-based sources, probable human health and ecological risks of PTEs (As, Cd, Pb, Cr, Ni, and Cu) in the urban soil of the Jashore district, Bangladesh. The USEPA modified method 3050B and atomic absorption spectrophotometers were used to digest and evaluate the PTEs concentration in 71 soil samples collected from eleven different land use areas, respectively. The concentration ranges of As, Cd, Pb, Cr, Ni, and Cu in the studied soils were 1.8-18.09, 0.1-3.58, 0.4-113.26, 0.9-72.09, 2.1-68.23, and 3.82-212.57 mg/kg, respectively. The contamination factor (CF), pollution load index (PLI), and enrichment factor (EF) were applied to evaluate the ecological risk posed by PTEs in soils. Soil quality evaluation indices showed that Cd was a great contributor to soil pollution. The PLI values range was 0.48-2.82, indicating base levels to continuous soil degradation. The positive matrix factorization (PMF) model showed that As (50.3 %), Cd (38.8 %), Cu (64.7 %), Pb (81.8 %) and Ni (47.2 %) were derived from industrial sources and mixed anthropogenic sources, while Cr (78.1 %) from natural sources. The highest contamination was found in the metal workshop, followed by the industrial area, and brick filed site. Soil from all land use types revealed moderate to high ecological risk after evaluating probable ecological risks, and the descending order of single metal potential ecological risk was Cd > As > Pb > Cu > Ni > Cr. Ingestion was the primary route of exposure to potentially toxic elements for both adults and children from the study area soil. The overall non-cancer risk to human health is caused by PTEs for children (HI=0.65 ± 0.1) and adults (HI=0.09 ± 0.03) under USEPA safe limit (HI>1), while the cancer risks from exclusively ingesting As through soil were 2.10E-03 and 2.74E-04 for children and adults, respectively, exceeding the USEPA acceptable standard (>1E-04).

Severe contamination of carcinogenic heavy metals and metalloid in agroecosystems and their associated health risk assessment

The contamination of toxic heavy metals (i.e., Cd, Cr, Pb, and Ni) and metalloid (i.e., As) (TMMs) is considered as a major cause of increasing incidences of human and livestock cancers, gastrointestinal disorders and neurological problems. The levels of these TMMS in soil, irrigation water, and plants like Salanum lycopersicum (tomato), Spinacia oleracea (Spinach), and Triticum aestivum (Wheat) samples were detected which were collected from various localities across 100 km around the city of Lucknow, India. This study reported that the concentration of TMMs was within the range of maximum allowable concentration (MAC) (FAO/WHO, 2011) in most of the agricultural soil, whereas, it was higher in irrigation water. The TMMs levels in the edible parts of vegetables and cereal were in the range 1.91-53.94 μg/g, 5.06-40.49 μg/g, 4.08-2312-29 μg/g, 0.43-51.48 μg/g, and 0.01-1.65 μg/g, respectively which was significantly higher than the MAC. The B_AF of Cd and Ni was very high in the edible parts of the vegetables and cereal samples indicating an entry of TMMs in food chain through the metal-contaminated irrigation water, even if TMMs are low in the field soil. The contamination coefficient (Cfi) and Ecological risk factors (Efi) of the TMMs were detected in the range of low risk in all agricultural soil. The Ecological risk index (E_RI) of TMMs was at moderate risk, indicating a mild impact of the metal toxicity in the agro-ecosystems but the high risk on the consumers. The daily intake (DI) of TMMs through vegetables and cereal was below the maximum allowable daily intake (MTDI) but the carcinogenic risk factor (CRs) potential of Cr, Cd, Ni, and As was observed significantly higher for these vegetables and cereal, which indicated a complex scenario of a far-future carcinogenic health hazard on consumers in densely populated city of Lucknow, India and its surrounding regions.

Cadmium contamination in agricultural soils of Bangladesh and management by application of organic amendments: evaluation of field assessment and pot experiments

In recent years, cadmium (Cd) contamination in agricultural soils and its subsequent transfer to crops is one of the high-priority environmental and public health issues of global concern, especially in densely populated developing countries like Bangladesh. However, no effective strategy has been introduced or implemented yet to manage Cd-contaminated soils in order to sustain agricultural production with no human health risks. In this study, agricultural soil samples were collected from 60 locations of 10 upazilas from Tangail district to assess the extent of soil Cd contamination. The Cd concentration ranged from 0.83 to 4.08 mg kg^-1 with a mean of 2.17 mg kg^-1 in topsoil (0-15 cm), and from 0.67 to 3.74 mg kg^-1 with a mean of 2.10 mg kg^-1 in subsoil (16-30 cm). The values of contamination factor (CF) indicated that all the sampling locations were found to be highly contaminated with Cd. Pot trials with the application of different doses of biochar and vermicompost in Cd-contaminated soil (0.8 mg kg^-1 Cd) revealed that integrated application of biochar (5 t ha^-1) and vermicompost (5 t ha^-1) was the best treatment that significantly (p < 0.05) reduced plant Cd concentration (72%) and increased the biomass of experimental crop, Red amaranth (Amaranthus cruentus). This combined treatment also significantly reduced the uptake of Cr (37%) when co-contamination was present. The study suggests the application of biochar (5 t ha^-1) in combination with vermicompost (5 t ha^-1) to reduce human health risk and increase crop production when the soil is loamy sand in texture.

Deciphering the origin of Cu, Pb and Zn contamination in school dust and soil of Dhaka, a megacity in Bangladesh

In recent decades, anthropogenic activities have resulted in road dust and roadside soil hosted metal(oid)s pollution in the urban environment. In the South-Asian megacity "Dhaka", schools are situated in the areas with high population density and high traffic emissions. As the school-going children are the most vulnerable receptor, school premises in Dhaka city represent an important yet overlooked exposure point to contaminated dust and soil. Therefore, the present study investigated the metal(oid)s (Cu, Pb, Zn and As) pollution in dust and soil at school compounds, explored their possible sources and estimated the associated human health risk. This study revealed that dust contained higher concentration of metal(oid)s than soil, and the Azimpur Govt. Girls School & College was identified as the most contaminated site. The enrichment of school dust with Cu, Zn and Pb were strictly related to the dense population and substantial traffic activity in the study areas. Arsenic content in school soil was several folds higher than its concentration in the upper crust. Natural and anthropogenic activities possibly posed a synergistic effect on such high soil As. The multivariate statistics suggested that Cu, Zn and Pb were likely to be originated from traffic-related activities, while Zr, Fe, Ti and Rb from natural sources, and K, Sr and Ca from industrial activities. The assessment of health risk suggested the children as a vulnerable receptor and ingestion was identified as the dominant pathway of dust and soil exposure. The hazard index (HI) values were lower than unity, suggesting no possible non-cancer health risk. Arsenic posed a lifetime carcinogenic risk to the population in the study area through soil ingestion and dermal adsorption.

Concentration, Spatial Distribution, Contamination Degree and Human Health Risk Assessment of Heavy Metals in Urban Soils across China between 2003 and 2019-A Systematic Review

This study provides an overview of the studies of heavy metal pollution regarding As, Cd, Cr, Hg, Pb, Cu, Zn and Ni in the urban soils throughout 71 cities of China, based on data from online literature, during the period 2003-2019. The concentrations, spatial distributions, contamination degrees and health risks of heavy metals in the urban soils were evaluated. The results demonstrated that the mean values of eight heavy metals all exceeded the soil background values in China, and the kriging interpolation method showed that the hot-spot cities with heavy metal contamination in urban soils were mainly concentrated in the southwest, southcentral, southeast coast, northcentral and northwest regions of China. The geoaccumulation index (Igeo) indicated that Hg and Cd were at moderate contamination levels and that the levels of the other six metals did not appear contamination. The pollution index (PI) showed that Cd and Hg reached high contamination levels, and the other metals reached moderate contamination levels. The integrated pollution index (IPI) and potential ecological risk index (PRI) indicated that the integral urban soils in the study areas ranked high contamination levels and moderate ecological risk degree, respectively, and Cd and Hg should be labeled as priority metals for control in the urban soils around China. The human health risk assessments for the heavy metals indicated that ingestion was the dominant exposure pathway for having adverse effects on human health. The mean Hazard index (HI) values of eight heavy metals all showed that adverse effects on human health were unlikely, and the mean carcinogenic (CR) values of As, Cr and Ni for children and adults all suggested an acceptable carcinogenic risk to human beings. In addition, children exposed to these heavy metals faced more serious non-carcinogenic and carcinogenic health threats compared to adults. The results could provide valuable information for demanding the better control of heavy metal pollution and mitigation of the adverse effects on residents by environmental regulators in national urban regions.