Contamination and Potential Risks of Heavy Metals in the Sediments of the Chari and Logon Rivers in N’Djamena, Chad

The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant life. The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant living beings. This study focuses on the pollution of sediments of the Chari and Logon rivers in the city of N’Djamena by heavy metals. The objective of this study is to evaluate the degree of contamination, the geo-accumulation index and the degree of the Pollutant Loading Index of some heavy metals (Pb, Cr, Cu, Mn and Cd) and iron in the sediments of the sampled sites. The average concentrations of heavy metals and iron in the sediments are: Pb (10.00 ± 00 μg/Kg to 126 ± 16.52 μg/Kg);Cr VI (0.13 ± 00 mg/Kg to 0.21 ± 00 mg/Kg);Cd (trace);Cu (0.08 ± 0.02 mg/kg to 3.23 ± 0.64 mg/kg);Fe (0.25 ± 0.00 mg/kg to 5.79 ± 0.00 mg/kg);and Mn (0.2 ± 0.00 mg/Kg to 1.1 ± 0.00 mg/Kg);in order of highest to lowest abundance: Fe > Mn > Cd > Cu > Cr VI > Pb for the Logon;Fe > Cu > Mn > Cd > Cr VI > Pb for the Chari and Fe > Mn > Cu > Cd > Cr VI > Pb for the Confluent. The contamination factors for all heavy metals range from no contamination to low contamination for the sediments analyzed. The geo-accumulation indices indicate that the sampled sites are not polluted. The same is true for Er and RI which confirm an absence of ecological risks in the analyzed sediments.

Comparison between BCR sequential extraction and geo-accumulation method to evaluate metal mobility in sediments of Dongting Lake, Central China

The form in which a metal exists strongly influences its mobility and thus, the effects on the environment. Operational methods of speciation analysis, such as the use of sequential extraction procedures, are commonly applied. The Dongting Lake, the second largest fresh-water lake in China, contains three China wetlands of international importance, the East Dongting Lake, South Dongting Lake, and West Dongting Lake. In this work, an optimized BCR sequential extraction procedure was used to assess the environmental risk of Cd, Cr, Cu, Ni, Pb and Zn in contaminated sediment of the Dongting Lake. The procedure was evaluated by using a certified reference material, BCR701. The results of the partitioning study indicated that in the lake sediments, more easily mobilized forms (acid exchangeable) were predominant for Cd, particularly in the samples from the East Dongting Lake. In contrast, the largest amount of Pb was associated with the iron and manganese oxide fractions and Cu, Zn, Cr, and Ni analyzed were mainly distributed in residual phase at an average percentage greater than 60% of the total metals. The potential risk to the lake's water contamination was highest in the East Dongting Lake based on the calculated contamination factors. On the other hand, the total metal content was determined as well by inductively coupled plasma and mass spectrometry (ICP-MS) and assessed by using geo-accumulation index. The assessment results using geo-accumulation index were compared with the information on metal speciation. Both were correspondent with each other.

Physico-chemical characteristics and heavy metal concentrations of copper mine wastes in Zambia:implications for pollution risk and restoration

Soil characterization is a vital activity to develop appropriate and effective restoration protocols for mine wastelands while insights into the total content of heavy metals in the soil is an important step in estimating the hazards that the metals may pose to the vital roles of soil in the ecosystem.This study addressed the following research questions:(1)To what extent do the physico-chemical characteristics vary between mine waste sediments and the nearby forest soil?(2)Are the concentrations of heavy metals high enough to be considered as toxic?and(3)Are heavy metals present in mine waste sediments potential sources of pollution?We hypothesized that the physicochemical characteristics of mine waste sediments are less favorably for plant establishment and growth while the concentrations of heavy metals are very high,thus restricting the success of revegetation of mine waste lands.Mine waste sediments were sampled following a diagonal transect across tailings dams,overburden dump sites and the local forest soil from the top layer(0-20 cm)using a closed auger.Samples were analyzed for arsenic,barium,lead,cadmium,cobalt,copper,chromium,nickel,vanadium,and zinc as well as for soil physico-chemical properties.The mine waste sediments were dominated by silt whilst the forest soil by sand particles,with significantly high bulk density in the former.Both the forest soil and overburden sediments were acidic than the alkaline tailings dam sediment.Total organic carbon and nitrogen contents were significantly low in mine wasteland substrates but the concentration of Ca and Mg were significantly higher in tailings dam substrate than the forest soil.The concentrations of available P,K and Na were similar across sites.The mean concentrations of heavy metals were significantly(p<0.01)higher in mine waste sediments than the forest soil;except for cadmium(p=0.213).The order of contamination by heavy metals on the tailings was Cu>Co>Ba>Ni>As>Zn>Pb>Cr>V>Cd,and that on the overburdens was Cu>Co>Ba>Ni>Zn>Cr>Pb>V>As>Cd.The pollution load index(PLI)was nearly twice higher for the tailings dam(8.97)than the overburden(5.84).The findings show that the copper mine wastes(the tailings dams and overburden waste rock sites)are highly contaminated by heavy metals;which,in turn,might pose serious hazards to human health and agricultural productivity.In addition,poor macro-nutrient availability,substrate compaction and soil acidity(particularly on overburden sites)coupled with toxic level of heavy metals would be the main challenges for successful phytostabilization of copper mine wastelands.

An Evaluation Performance of Potential Pollution of Arsenic, Chromium and Cadmium in the Road Side Soil of Kirkuk City, Northern Iraq

The present work is to evaluate and investigate the distribution of heavy metals (As, Cr and Cd) and to assess the road side samples contamination using an Index (SEPI), (CPI), (GAI), (CF) and (PLI). From right and left Khasa in Kirkuk city, road soil samples were collected in order to estimate the probable contamination level of heavy metals (Cd), (As) and (Cr) in the study area. The heavy metal concentrations were determined in the way side samples by using (ICP-MS) technique. The 22 samples have collected in August, 2013. The results of average levels of heavy metals revealed Cr, As and Cd recorded the highest concentration of (178.6 ppm, 10.4 ppm and 0.599 ppm) in right Khasa respectively. These heavy metals are recorded the lowest value (165.8, 8.29 and 0.4 ppm) in left Khasa respectively. However, the concentration of Cr and As was higher than the studied worldwide permissible of contaminated soil. The highest (SEPI) for As in right Khasa and Cr in left in Khasa seems therefore to be that this road side soil is the most polluted in the city of Kirkuk classified moderately contamination. The accounted of (CPI) for As, Cd and Cr ranged from 0.82 to 1.30 with average 1.01 and 0.6 to 1.12 with an average 0.78 in right and left Khasa respectively. The highest values in the right Khasa which suggest multi-elements contamination and suggested this area of study area received more heavy metals comes from manmade and industrial activities. The GAI showed a moderate contaminated with Cd in right Khasa of study area, while the other metals are in their uncontaminated level. The CF results has been showed by a considerable contamination metals (As, Cr and Cd) in of right Khasa, but low to moderate contamination in left Khasa. The results of (PLI) revealed a deterioration of site quality in all samples of Kirkuk city. Thus the evaluation methods revealed that the studied areas especially right Khasa impacted with heavy industrial activity, phosphate fertilizer, emission of gasses from automobile manufacture tire abrasion and workshop causing an increasing in metal concentrations towards the right Khasa.

Assessment of Heavy Metals Concentration and Enrichment Levels in Soils around Quarries and Barite Mine Sites in Part of Akamkpa and Biase Area, Southeastern Nigeria

Geochemical investigation of the soils around quarry and barite mine sites in part of Akamkpa and Biase area of Southeastern Nigeria, was carried out to assess the concentration and enrichment levels of some heavy metals and trace elements in the soils. The investigation involved the collection of fifteen (15) soil samples between the depth of 15 - 30 cm. The samples were dried at room temperature, prepared and analyzed for heavy metals using inductively couple plasma mass spectrometer. The result shows that the concentration of Co, Cr, Nb, Pb and Sn were higher than the average shale values around the quarries while Ba, Pb and Sn were higher around the barite mines. The contamination factor indicates low to minimal contamination and low to considerable contamination around the quarries and barite mines respectively. While the Enrichment factor indicates minimal to significant enrichment around the quarries and minimal to extremely high enrichments around the barite mines. The result of the factor analysis and spatial distribution of the heavy metals suggests that the metal concentration and enrichment were controlled by the rock types, weathering and anthropogenic activities around the mine sites.

Assessment of the Quality of Sediments and Agricultural Soils: Case of the Ity-Floleu Area in the Prefecture of Zouan-Hounien, Western Côte d’Ivoire

The objective of this study is to assess the level of metal contamination of sediments and agricultural soils in the Ity-Floleu zone. The concentrations of trace elements (Fe, Mn, As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) were measured in different seasons over two successive years. The sediment pollution index made it possible to note that the sediments and agricultural soils of the various stations studied are highly polluted in all seasons. The calculation of the geoaccumulation index indicates that surface water sediments most often experience extreme or moderate pollution in As, Cd, Cu, Hg and Zn in the dry or rainy season except in Pb in some cases. We observed that the sediments of the Cavally river present a serious pollution due to extreme anthropic activities carried out along the river. Over the entire region, the results of the potential ecological risk index (RI) indicate that all the sediments and agricultural soils analysed present a moderate ecological risk in terms of Pb and Zn in certain cases and an ecological risk is observed low bound to other metals in all seasons. This metallic pollution generated by human activities in this region can have consequences for the environment and biodiversity.

Spatial distribution and source identification of heavy metal pollution in roadside surface soil:a study of Dhaka Aricha highway,Bangladesh

Introduction:In this study,metal pollution and their sources in surface soils were evaluated by pollution indices and multivariate statistical techniques in association with a geographical information system(GIS).Methods:Surface soil samples were collected in dry season from different locations of Dhaka Aricha highway and analyzed by energy dispersive X-ray fluorescence(EDXRF).Results:Thirteen different metals were found in the tested samples.Pollution indices are determined by enrichment factor in an order of Zr>Sn>P>Mn>Zn>Rb>Fe>Ba>Sr>Ti>K>Ca>Al.The resulting geoaccumulation index(Igeo)value shows the following order:Sn>Zr>P>Mn>Zn>Rb>Fe>Ba>Ti>Sr>K>Ca>Al.Contamination factors(CFs)of the metals range from 1.422 to 3.979(Fe);0.213 to 1.089(Al);0.489 to 3.484(Ca);1.496 to 2.372(K);1.287 to 3.870(Ti);2.200 to 14.588(Mn);5.938 to 56.750(Zr);0.980 to 3.500(Sr);2.321 to 4.857(Rb);2.737 to 6.526(Zn);16.667 to 27.333(Sn);3.157 to 16.286(P);and 0.741 to 3.328(Ba).Pollution load index calculated from the CFs indicates that soils are strongly contaminated by Zr and Sn.Principal component analysis(PCA)of parameters exhibits three major components.R-mode cluster analysis reveals three distinct groups in both site and metal basis clustering that shows a similar pattern with the PCA.Conclusions:These results might be helpful for future monitoring of further increase of heavy metal concentrations in surface soils along highways.

An assessment of trace metal pollution indicators in soils around oil well clusters

Due to the metallic ion constituents of crude oil,environmental levels of toxic metals are often exac-erbated when oil is spilt.Biseni community plays host to numerous oil production companies in Bayelsa state,Nigeria.However,the tendency for this clan to be flooded,particularly owing to its lowland fea-tures has continued to negatively impact on the environment.Sometimes,floods are accompanied by spilt residual oil that encroach living areas,thus leading to the contamination of open water bodies,underground water resources,and fish and crop farms.This study surveyed the impact of oil seepages from oil well clusters on the overall soil quality by applying trace metal pollution indicators.Trace metals were analyzed by atomic absorption spectrometry,and concentration ranged from 5893.0-6263.8 mg/kg,0.03e11.52 mg/kg,3.15e6.46 mg/kg,4.46e58.64 mg/kg,13.61e29.83 mg/kg,0.23e0.73 mg/kg,8.32 e20.69 mg/kg,and 4.24e9.31 mg/kg for iron,copper,nickel,lead,zinc,cadmium,chromium and cobalt respectively.Concentrations were within target limits stipulated by the Department of Petroleum Re-sources,Dutch standard limit and World Health Organization.Zinc and chromium showed the strongest correlation(r¼0.92,p<0.05)in the study area,whilst one-way ANOVA revealed equality(p>0.05)among the different sampling points.This is evidence that the field area is affected by similar contam-ination source.Whereas,the micro-pollutant metals depicted significant variability(p<0.05),probably due to the outlier concentration of iron.Overall,lead was the most contaminating metal,while location BNS2(0.3m)was the most considerably contaminated area.Enrichment factor revealed the anthropo-genic origination of lead.Index of geo-accumulation of lead ranged from moderate to heavy contami-nation,with lead recording very high contamination factor,and the degree of contamination depicting considerable risk,especially at the top soil.Pollution load index showed most contamination(moderately polluted)at BNS2.Quantification of contamination showed relative contamination for most locations,whereas potential ecological risk index mostly depicted low risk,apart from the exhibition of moderate risk of lead and cadmium at BNS2.Conversely,sum of pollution indices and risk index revealed low contamination and low risk respectively.