Distribution Of Heavy Metal Contamination Research Articles

Assessing the Ecological Risks and Spatial Distribution of Heavy Metal Contamination at Solid Waste Dumpsites

Assessing the Ecological Risks and Spatial Distribution of Heavy Metal Contamination at Solid Waste Dumpsites

Spatial distribution of heavy metal contaminants: The effects of water-sediment regulation in the Henan section of the Yellow River

Water-sediment regulation (WSR) affects sediment transport in the middle and lower reaches of the Yellow River through periodic interception of sediment by dams and alteration of downstream flow rates, which leads to redistribution and recycling of elements. In this study, based on the evaluation of seven heavy metals (V, Cr, Ni, Co, Cu, Zn, and Cd) in water, sediment and suspended particulate matter (SPM) in the Henan section of the Yellow River, the effects of WSR on the redistribution and risk of release of metals to the downstream aquatic environment were investigated, and the range of impact and pollution sources were determined. Dissolved metals were well below guideline values for water quality, but Cd, Cr, and Cu were enriched in the sediments, especially in the reservoir, and the pollution load index (PLI) results indicated that the contamination in the study area remained very low. The level of contamination was decreased, and metals migrated downstream after WSR. The chemical speciation of metals indicates that anthropogenic input of metals occurs in upstream tributaries, and the risk of release of metals in the sediments increases after WSR, but the spatial distribution of the risk is more homogeneous. The distribution coefficient explains the distribution pattern of pollution, where SPM carries pollutants to the downstream while formed surface sediments through natural deposition during the sand-discharge stage. Based on geological and field investigations, upstream gold mining and downstream riverbank cultivation activities in the study area are potential sources of Cu and Cd pollution. These findings are crucial to the better understanding of patterns of metal release from artificial impoundments in river systems and provide a theoretical basis for ecological development in the Yellow River Basin.

Spatial Distribution of Heavy Metal Contamination in Road Dust Samples from an Urban Environment in Samsun, Türkiye.

Road dust is an environmental pollution indicator created by human activities for urban land use. This study aimed to determine the spatial distribution pattern and degree of trace metals in road dust samples collected from 5 different areas in Samsun city center. The trace metals of Mn, Co, Cd, Cr, Cu, Ni, Pb, and Zn are the most examined contaminants in road dust because their hot-spot areas were mainly associated with high traffic density. Factors governing potential contamination index range values of Co, Cr, and Ni were 0.34-0.62, 0.23-0.78, and 0.24-0.48 as the lowest contamination. However, potential contamination index values of Cu, Pb, and Zn in the main road site were 1.80, 2.32, and 2.84 suggesting that relatively high values were uncontaminated to moderately. Pollution assessment methods were applied to toxic metals and revealed that Samsun city had been affected as uncontaminated to moderately contaminated by anthropogenic emission of heavy metals.

A two-dimensional analytical model for heavy metal contaminants transport in permeable reactive barrier.

Permeable reactive barrier (PRB) remediation technology has been widely used in the remediation of groundwater contamination. In numerical simulations, neglecting the non-uniform distribution of heavy metal contamination along the depth may lead to deviations between simulation results and reality. The distribution of heavy metals in the soil layer around a non-ferrous mining area in Hezhou, Guangxi, southern China was investigated, and it was found that the standard Gaussian function could well describe the non-uniform distribution of heavy metals in the soil layer. A two-dimensional analytical model solved by the finite element method was used to simulate the migration process of heavy metal contamination in the aquifer and PRB. The results show that the uniform distribution of contaminants along the depth ignores the dilution effect, which may underestimate the service life of the PRB and lead to an overly conservative design of the PRB. The breakthrough time of the PRB decreases with the increase of the maximum initial concentration (Cin,max) and the high concentration range (σ), and increases almost linearly with the barrier thickness (Lw). An optimal design method for PRB location and thickness is proposed, which can provide a reference for the engineering application of PRB.

Phytoextraction of anthropogenic heavy metal contamination of the Blesbokspruit wetland: Potential of wetland macrophytes

Blesbokspruit wetland is one of the least conserved ecosystems in the Southern Africa region with active and latent threats of anthropogenic contamination stretching over decades of mining wastewater discharge, agricultural run-off, and a consistent influx of untreated sewage. This study provides an insight into the present-day spatial distribution of heavy metal contamination and the role of localised macrophytes in their phytoremediation. With exception of the first sampling point, the concentration of heavy metals in water samples throughout the wetland was within limits however findings from sediment samples were the inverse. The concentrations of Chromium and Nickel significantly exceeded both effect range low (ERL) and effect range medium (ERM) limits (250-430 mg/Kg and 73-151 mg/Kg respectively) as set out by international sediment quality guidelines. Emergent- Phragmites australis, Typha capensis, and free-flowing-Eichhornia crassipes macrophytes, which are naturally localised to the wetland were found to have varying bioaccumulation potential for different heavy metals; Bioconcentration of heavy metals in emergent macrophytes was relatively low especially for Nickel and Chromium compared to free-flowing macrophytes. E. crassipes accumulated significant amounts of the heavy metals with root concentrations of up to 17.23, 116.6, 330.5, and 342.9 mg/Kg for Arsenic, Lead, Nickel, and Chromium respectively. The emergent macrophytes were however found to bioconcentrate Arsenic up to 1.15 L/Kg (T. capensis) and 9.9 L/Kg (P. Australis) at sites 4 and 5 respectively. Findings with regards to bioconcentration especially of the E. crassipes, validate recommendations for the utilization of hyperaccumulating macrophytes for the natural recovery of these heavy metals towards alleviating the anthropogenic stress on this valuable ecosystem.

Al and Fe Heavy Metal Concentrations in the Vegetative and Root Parts of Dicranopteris linearis, Nephrolepis bifurcata, Stenochlaena palustris and Acrostichum aureum Grew in Highly Weathered Soil

Phytoremediation is a plant function that degrades, eliminates, and inactivates potentially hazardous and toxic compounds in the polluted water, soil, and air. In phytoremediation mechanisms, phytodegrading enzymes break down the pollutants taken up by plants (phytodegradation). Additionally, the microorganisms found in the plant-related rhizosphere can also degrade the pollutants in the soil (rhizodegradation). The plants can extract the pollutants from the soil and accumulate them in their tissues (phytoextraction) or immobilise the contaminants in their root zone, remove the harmful compounds from the water and soil through transpiration into the atmosphere, and regulate the heavy metal pollutants across their root system (phytostabilisation). In this study, researchers characterised the development and aptitude of different fern species to remediate the heavy metal pollutants present in the highly weathered soil (i.e., laterite soil). For this purpose, soil samples from 3 different sites in Perak, Selangor and Johor were collected. The phytoremediation ability of 4 different fern species (i.e., Dicranopteris linearis, Nephrolepis bifurcata, Stenochlaena palustris and Acrostichum aureum) was determined to understand the pattern and distribution of heavy metal contamination in soil. The ICP-MS technique was utilised to determine the concentration of heavy metals. The results indicated the presence of a high concentration of heavy metal at many of these sites, while the concentration of Al and Fe ions varied. In addition, a significant difference (P<0.0001) in the concentration of heavy metals was discovered between fern species. All the interactions were detected using the Analysis of variance (ANOVA) technique. Phytoremediation is considered an alternative technique for reducing the heavy metal concentration in soil in light of various factors that lead to the accumulation of heavy metals. Furthermore, the remediation of numerous sites that are polluted with heavy metals, like landfills, is a cost-effective solution employing green technologies, like phytoremediation.

Heavy Metals and Physicochemical Parameters Evaluation in the Upper Reaches of Bonny River, Niger Delta, Nigeria

The objectives of the study were to determine distribution of heavy metal contamination in water, sediments and biota (Callinectes amniciola) of the upper reaches of the Bonny Estuary and to determine the impact on physicochemical characteristics of the water body. Sampled was from January to June 2020. The physicochemical parameters of the water varied slightly across the months but were within FEPA/WHO (2003) acceptable limits. Furthermore; the study compared the seasonal variations and determination of Bio-accumulation Factor (BF) of C. amnicola with respect to sediment. The study site is a tidal creek that drains into the main Bonny River channel within Niger Delta, Nigeria. The sampled locations/stations include Trans-Amadi slaughter in Azuabie {N4°81'49.9 and E7°04'63.4}, Okpoka Creek in Abuloma {N4°78'02.43 and E7°06'66.12} and Okirika Jetty {N4°73'70.04 and E7°09'56.93}. Samples of surface water, sediments and swimming crabs were collected from three different stations which were at least 1000 meters apart. The results of this study show that concentrations of the heavy metals (Fe and Zn) were both higher in the three media than the approved limits prescribed by the local regulatory authority. Although Cu was relatively within acceptable limit in the three media. There is therefore the need to control the anthropogenic activities within or around the river. This will help to prevent effluent and solid waste discharges that lead to increase in the concentration of heavy metals in the aquatic environment. Routine monitoring should be encouraged to identify the major sources of heavy metals introduction into the river and their impacts on the aquatic resources.

Spatial variation of heavy metal contamination in roadside soil from hilly terrain of the north-western Himalaya

ABSTRACT Fuel-based vehicular emission has been recognised as a potential contributor to the declining air quality and heavy metal contamination of soils. The present study investigated heavy metal contamination in roadside soil along national highway (NH)-21 and a link road in hilly terrain of the Kullu district, north-western Himalaya, India. The soil samples were analysed for pH, EC and heavy metals, viz., Zn, Fe, Mn, Cu, Pb, Ar and Cr. The heavy metal concentrations were evaluated as per the guidelines provided by competent authorities. The spatial distribution of heavy metal contaminants was depicted in maps using the GIS platform. The pH of the soil was slightly acidic to neutral. The reference sites from the rural area represent the lower heavy metals contamination comparison to the locations along the highway. The heavy metal concentrations decreased with the increasing distance from the edge of the road, while their distribution and mobility were influenced by natural as well human-induced sources. The present study provides the baseline data to optimise the scale of sampling in the hilly terrains that is capable of capturing the effect of the diffuse source for efficient pollution abatement strategies.

Heavy Metal Contamination and Ecological Risk Assessment in the Soil of Tannery Industry at Savar

Heavy metal contamination in soil is considered a global crisis and its bulk proportion are in developing countries like Bangladesh. Five heavy metals such as Cd, Cr, Pb, Cu and Ni were investigated in the soil of Savar tannery industrial estate. The decreasing trend of metals was observed in soil as Cr&gt;Cu&gt;Ni&gt;Pb&gt;Cd. According to US EPA guideline, Cr was heavily polluted at the selected locations. Cu was highly polluted, whereas Cd and Pb were not polluted and Ni was moderately polluted. On the basis of Pearson’s correlation Cd-Pb, Cd-Cu, Cu-Ni, Ni-Cu, Ni-Pb were significantly correlated. From the pollution index, metal pollution of sediments was found in the order as Cr&gt;Cu&gt;Pb&gt;Cd. Degree of contamination and modified degree of contamination were higher in the dumping zones. The geo-accumulation index for Cr showed moderate to extremely contaminated. Ecological risk arrayed in the order of Cr&gt;Cu&gt;Ni&gt;Pb&gt;Cd in the soil of study area. Geographic information system (GIS) was also used to map the spatial distribution of heavy metal contamination in the soil. This study recommended that continuous monitoring of heavy metal contamination should be directed to assess their risk in the soil of tannery industry at Savar.&#x0D; Chemical Engineering Research Bulletin 21(2020) 106-113

A Roman provincial city and its contamination legacy from artisanal and daily-life activities.

Roman metal use and related extraction activities resulted in heavy metal pollution and contamination, in particular of Pb near ancient mines and harbors, as well as producing a global atmospheric impact. New evidence from ancient Gerasa (Jerash), Jordan, suggests that small-scale but intense Roman, Byzantine and Umayyad period urban, artisanal, and everyday site activities contributed to substantial heavy metal contamination of the city and its hinterland wadi, even though no metal mining took place and hardly any lead water pipes were used. Distribution of heavy metal contaminants, especially Pb, observed in the urban soils and sediments within this ancient city and its hinterland wadi resulted from aeolian, fluvial, cultural and post-depositional processes. These represent the contamination pathways of an ancient city-hinterland setting and reflect long-term anthropogenic legacies at local and regional scales beginning in the Roman period. Thus, urban use and re-use of heavy metal sources should be factored into understanding historical global-scale contaminant distributions.

Analysis of the spatial distribution of heavy metals in an area of farmland in Sichuan province, China

To accurately visualize the spatial distribution of heavy metal pollution and provide information that assists in remediating farmland soil, this study employed GIS technology and collected 0–20 cm-depth surface soil and shallow groundwater samples from farmland in Jianxin Village, Xiba Town, Wutongqiao City, Sichuan Province, China. The soil samples were decomposed using a high-temperature closed digestion method, and the contents of Cr, Cd, Pb, As, Cu and Zn were determined using ICP-MS. A geographic semi-variogram analysis was then conducted to delineate spatial variations in the heavy metal concentrations within the soil, and a spatial distribution map of heavy metals in the soil was drawn using ArcGIS10.2 software based on a GIS Kriging interpolation spatial structure analysis. The results showed that all heavy metal element concentrations exceeded the soil background values of Sichuan Province; the exceeded rates of Cr, Cd, and Zn were 100%. All Cd samples exceeded the soil baseline value, and the pollution accumulation of Cr, Cd, and Zn was determined as being serious. Through a comparison of cross-validation methods, a theoretical optimal semi-variogram model of six heavy metal elements was obtained. Indexes C0/(C0 + C) of Cd, Pb, As, Cu, and Zn were in the range of 48–75%, which showed that their contents related to structural factors, such as the soil parent material and topography, and also to non-structural factors such as human activities. The index C0/(C0 + C) of Cr was more than 75%, which indicates that its content is mainly related to non-structural factors and human activities. The spatial correlation followed the order of Cu > Cd > Pb > Zn > As > Cr. The vertical distribution of heavy metals was greatly affected by the soil physical properties: the Cu and Pb contents of sandy soil decreased at first and then increased with depth; the Cr, Zn, and As contents first increased and then decreased with depth; and the Cd contents decreased with depth. In clay soil, there was little change in the Cu content with depth; the Cd, Zn, Pb, and As contents first decreased and then increased with depth, and the Cr content increased first and then decreased with depth. These results show that visualizing the spatial distribution of heavy metal contamination using GIS technology is significant for providing information that can be used to remediate farmland soil.

Distribution, Association, and Ecological Risk Evaluation of Heavy Metals and Influencing Factors in Major Industrial Stream Sediments of Chandrapur District, Central India

The accumulation of heavy metals in stream sediment depends on various influencing factors. Sediments are aggregation of number of species along with organic debris. Accretion of heavy metals on sediment is the outcome of absorption by fine-grain inorganic particles of clays, adsorption of hydrous ferric and clays, and complexation with natural organic matters. These processes are regulated by different influencing factors including TOC and pH. This study reveals the spatial distribution of potentially toxic heavy metals (Cd, Hg, Pb, Co, Cu, Cr, Ni, and Zn) and assessment of contamination levels to find out the role of TOC and pH in distribution of heavy metal contamination in major industrial stream sediment in Chandrapur district, Central India. The pollution indices and multivariate statistical analysis were carried out to identify the correlation between various parameters. The concentration of anthropological derived heavy metals is higher in TOC-rich area. PCA and HCA study reveals that heavy metals are significantly correlated with TOC of the sediments, while Ni is associated with pH. Chromium shows the ambiguous behavior towards association with pH and TOC. The study also reveals that there is urgent need for assessment of Wardha River and Erai River basins because there could be hotpots for heavy metal contamination.

Heavy metal pollution assessment in paddy fields and dryland in Bandung District, West Java

Excessive use of fertilizers and pesticides causes the accumulation of heavy metals in intensive agricultural land. Besides, the development of industries around the agricultural area further aggravates the accumulation of heavy metals. This study aimed to assess spatial distribution of heavy metal contamination in agricultural land in Bandung District. In this study, seven concentrations of heavy metals (Cr, Pb, Cd, Co, Cu, Ni, and Zn) in soils were analysed from 273 sampling sites in paddy and horticultural lands in Bandung Regency, Indonesia. The single pollution index (PI) and the Nemerow Integrated Pollution Index (NIPI) were calculated for each surface sample (0-20 cm) to assess the level of heavy metal pollution. Ordinary Krigging (OK) method was used to delineate the spatial distribution of heavy metals. The results show that the average values of all PIs and NIPI values are at a safe level, except for cobalt which showing slightly polluted. The analysis showed that around 3.23 and 8.76% of soil samples were slightly contaminated with cadmium and cobalt, respectively. The finding can be used as a reference for stakeholders to manage paddy fields against heavy metal contamination.

Spatial distribution of heavy metal contamination and uncertainty-based human health risk in the aquatic environment using multivariate statistical method.

Heavy metal contamination in the aquatic environment is one of the most serious health issues worldwide. In this study, an evaluation framework is developed to identify the sources and health risk of heavy metals (i.e., As, Hg, Cr, Cu, Zn, Pb, and Cd) contamination in the North Canal of Fengtai District, China, which is based on multiple approaches, including multivariate statistical method, health risk assessment, and uncertainty analysis. Spatial distribution of these heavy metals could exhibit their impact on the aquatic environment. Pearson's correlation analysis shows that a majority of the correlations between different heavy metals are not significant due to the differences in sources of heavy metals. Principal component analysis indicates that there are four principal components to explain 91.381% of the total variance. Moreover, health risk reveals that hazard quotient values are in low levels, ranging from 0.48 to 0.74, relative higher quotient levels could be observed in the northern section. The carcinogenic risk of Cd has exceeded the acceptable level in S1, S3, and S7. Sensitivity analysis ensures the reliability of health risk assessments. Furthermore, some specific recommendations are given to help decision-makers develop more comprehensive strategies for improving water environment quality.

Environmental and health risks of metal-contaminated soil in the former tannery area of Hazaribagh, Dhaka

Soil and plant samples collected from Hazaribagh, the former tannery area in Dhaka, Bangladesh, were analyzed for heavy metals (Cr, Pb, Ni, Zn, Cd, and Cu). The pollution and health risks of the metals were assessed with commonly used indicators. The mean soil Cr concentration was 4321 mg/kg (range 294–23,148 mg/kg). Most sites had a moderate to high degree of contamination and were classified as extremely polluted (Pollution Load Index > 1). The non-carcinogenic hazard index was greater than 1 for Pb and Cr for both children and adults, which indicates considerable non-cancer health risk. The combined cancer risks for Pb and Cr exceeded the allowable range of 1 × 10−6–1 × 10−4 for most sites (8 out of 11 sites in the case of adults, all sites in the case of children) with Cr being the dominant contributor and oral ingestion the primary pathway. The cancer and non-cancer risks for children were 26- and 3-fold higher, respectively, than for adults. Among all heavy metals, Pb and Zn were the most susceptible to leaching and becoming mobilized in groundwater. Concentrations of Pb, Cr, and Zn in edible parts of vine spinach (Basella alba) exceeded safe limits. However, Pb and Cu showed significant accumulation in plants (Mean Transfer Factor of 1.064 and 0.94, respectively, for Pb and Cu), while Cr exhibited relatively lower bioavailability. The spatial distribution of heavy metal contamination and associated risks presented in this study will allow policymakers to pinpoint areas of intervention for remediation.

Spatial distribution of heavy metal contamination in mollisol dairy farm

To accurately visualize the spatial distribution of heavy metal pollution and provide basic information on soil remediation in dairy farm, Geographic Information System (GIS) is used for optimization of sample collection and data analysis. Based on GIS technology, dairy manure, 10 cm-depth surface soil, 50 cm-depth sub soil, and surface water samples were collected from dairy farm in Dulbert Mongolian Autonomous County, Daqing City, Heilongjiang Province in China. The spatial distribution and assessment of heavy metals were performed by using GIS inverse distance weighted interpolation and pollution index method. The single factor pollution index value of As element in the soil was found to indicate the class of extreme contamination, whereas Ni in both surface water inside and outside the farm, and Sb in the cow drinking water were assigned to the level of moderate contamination. The comprehensive pollution index implied serious contamination for soil samples, slight contamination for water samples and safety for manure samples, respectively. Comprehensive score for heavy metal elements followed the orders of As>Zn>Cr>Ni>Cu>Pb>Cd>Hg. The horizontal pollution that mainly occurred in the middle and east regions was increased from north to south, and west to east district. Historically, the dairy farm belonged to heavily polluted saline-alkali soil, where the heavy metals might enter the food chain through transportation from soil to water, the cows, and eventually to the milk and human body. Visualizing spatial distribution of heavy metal contamination by using GIS technology will be of significance to provide useful information for soil remediation of dairy farm.

Geospatial distribution of heavy metal contamination in Ewekoro Limestone, SW Nigeria

Limestone exploration has numerous advantage to the nation’s economy. However, major anthropogenic activities such as mining of such mineral deposits causes environmental contamination due to heavy metals pollution. The presence of heavy metals such as lead, cadmium, mercury and arsenic can interfere with the biochemical pathways by interaction with enzymes and proteins. They equally have the capacity to alter the DNA repair mechanism and act as the inducers of carcinogenesis. The focus of the research is therefore to detect the extent of heavy metals contaminations within the sampled Ewekoro limestone, southwestern Nigeria and to ascertain the risks they posed to the quarry workers, miners and the people residing in the study area.

Partition of Cu and Pb in a Two-Stage Fluidized-Bed Waste Gasification System

In this study, a two-stage fluidized-bed gasification system was used to determine the distribution of heavy metal contaminants in simulative waste and evaluate the effect of the bed operating temperature, Equivalence ratio (ER), and Steam/Biomass ratio (S/B) in stage 1. The heavy metal concentrations in bed materials and fly ash were measured in two stages. The results show that as the operating temperature of stage 1 increased, the quantity of heavy metals entrapped by stage 1 bed material decreased, while that captured by stage 2 bed material increased. The less volatile Cu was mostly entrapped in stage 1 bed material. The ER and S/B results show that increasing the ER and S/B caused a slight increase in the concentrations of heavy metals entrapped in stage 1 and stage 2 bed materials. However, the influences of ER and S/B were less than that of temperature. The major factors affecting the heavy metal distribution were the operating temperature and the heavy metal volatility. Stage 2 bed material was able to entrap gaseous heavy metals or particles containing heavy metals by particle filtration and chemical adsorption. Thus, the heavy metals (Cu and Pb) had a downward trend after passing through stage 2.

The spatial and vertical distribution of heavy metal contamination in sediments of the Three Gorges Reservoir determined by anti-seasonal flow regulation

The contamination of heavy metals in sediments of the Three Gorges Reservoir (TGR) is increasingly concerned as a major issue for water quality since the full impoundment. In this study, the sediment profiles in the riparian and submerged areas from Fuling to Zigui in the middle-low TGR mainstream were collected to investigate the stratified distribution of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and assess their contamination and potential eco-risk. The results showed that the concentrations of these metals in the riparian sediments did not present a marked spatial trend except the concentrations of Cd that increased towards the dam. However, the metal concentrations (except Cd) in the submerged sediments were generally higher near the dam. The concentrations of heavy metals in the riparian sediments did not show marked vertical variation, while in the submerged sediments they fluctuated dramatically with depth, indicating the metal accumulation processes in last few years. Sediment grain sizes as an indicator of hydrodynamic regimes dominated the vertical distribution of heavy metals over organic matters and Fe/Mn oxide/hydroxides. The sediments from both riparian and submerged areas of the TGR were contaminated by anthropogenic metals of Cd, Cu and Pb that were mainly from the ore mining, fossil fuel combustion, agricultural pollution and atmospheric deposition. Cadmium was a major metal pollutant in the sediments with a high contamination and potential eco-risk level. The results of this study indicate that the sorting of sediments with the anti-seasonal flow regulation determines the spatial and temporal distribution of heavy metal contamination in the sediments, and the impoundment stages of the TGR in history regulate the accumulation processes of the metals.

Geochronological and spatial distribution of heavy metal contamination in sediment from Lake Naivasha, Kenya

Sediment cores hold large information on the history of human interactions with lakes and surrounding environments. Hence, this study investigated the geochronological and heavy metals characterist...