Potential Ecological Risk Factor Research Articles

Distribution, source identification, and contamination level of trace metals in the sediment of the Shari-Goyain River in Bangladesh: Implications for ecological health risks

The major issue associated with coal mine drainage is its contribution to river pollution, which occurs at the local, regional, and global levels. The pollution of surface sediment by heavy metals is a major environmental and health concern in coal mining and downstream areas. This study explored the concentrations of eight metal components in the sediments from the Shari-Goyain River of Bangladesh. The trend of decreasing metal concentration was identified as Fe > Mn > Ni > Zn > Cu > Cr > Pb > Cd in sediment. The level of metal pollution in the study area was assessed by using various indicators like geo-accumulation index (Igeo), pollution load index (PLI), contamination factor (CF), potential ecological risk factor, and risk index (RI). The sediment in the river exhibited PLI values ranging from 0.133 to 0.543, suggesting a low level of pollution from the evaluated heavy metals (PLI < 1). The mean Igeo showed that the study area was unpolluted whereas Ni showed unpolluted to moderately polluted status. For most of the metals, the sediment samples recorded a low degree of contamination (CF < 1) except Pb, Cd, and Ni which exhibited moderate degree of contamination (1 ≤ CF < 3). Through the application of various statistical analyses, coal mine drainage has been identified as the possible source of pollution of the analyzed metals in the Shari-Goyain River. However, the risk index and RI suggested a low risk of metal pollution in the studied areas. To improve the environmental conditions of the Shari-Goyain River, it is crucial to construct permanent sediment quality monitoring stations and conduct extensive ecological investigations.

Appraisal of river sediments in southwestern Nigeria with a special focus on trace metals: Occurrence, seasonal variation, sources, and health risks

Metal toxicity can negatively affect aquatic biodiversity. In this study, eight trace metals (TMs) (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in 72 sediment samples collected from six major rivers in Southwestern Nigeria between the dry and wet seasons of 2019 and 2021by inductively coupled plasma optical emission spectrometry (ICP-OES). Pollution indices such as enrichment factor, geo accumulation index, pollution load index, and potential ecological risk index were evaluated. At both seasons, the mean TM concentrations (mg/kg) followed a similar trend in decreasing order as Cu (589.32 ± 582.00) > Fe (269.52 ± 127.09) > Zn (162.68 ± 103.14) > Mn (61.89 ± 29.87) > Pb (10.09 ± 5.34) > Cd (8.59 ± 2.20) > Cr (8.72 ± 2.60) > Ni (3.16 ± 1.55) across locations and seasons. Distinctive distribution profiles characterized individual metals coupled with significant seasonal shifts in concentration (p < 0.05). Comparison with recommended national limits for Cd, Cu, Fe, Ni, Pb, and Zn suggested potential human and ecosystem health risks for the local population, while all the metals are above US EPA residential criteria. Cd displayed considerable, or very high ecological risks across all locations and seasons. Overall, Cd was considered a key potential ecological risk factor. Data revealed more anthropogenic than natural sources influenced sediment-bound TMs based on principal component analysis (PCA) and positive matrix factorization (PMF). The findings in this report provide fundamental information that would allow more effective monitoring through the establishment of critical policies and measures to reduce TMs levels in the environment.

Assessment of heavy metals and ecological risk of pangas (Pangasianodon hypophthalmus) and tilapia (Oreochromis niloticus) farms in Bangladesh

An investigation was conducted to evaluate the contamination levels of heavy metals (As, Pb, Cd, Cr and Cu) in surface water and sediment of pangas (Pangasianodon hypophthalmus) and tilapia (Oreochromis niloticus) aquaculture farms in four regions (Mymensingh, Cumilla, Bogura, and Jashore) of Bangladesh. The ecological risk index (ERI) was determined to assess the water quality index. The water contained As concentrations of 3.60–11.14 µg/L; Pb of 1.73–3.83 µg/L; Cd of 1.26–23.12 µg/L; and Cu of 6.08–45.22 µg/L; whereas the sediments contained As concentrations of 2.84–4.57 mg/Kg; Pb of 8.32–16.07 mg/Kg; and Cd of 0.22–12 mg/Kg. Most locations had moderate to low levels of pollution, and the levels of contamination decreased from Cd to Pb to As to Cr. The declining sequence of potential ecological risk factors of toxic metals in sediment was Cd &gt; Pb &gt; As &gt; Cr. Cd's potential ecological risk factor ranged from 2.84 to 21.58, making it one of the elements with the highest potential for ecological danger compared with other metals in this study. The Igeo values for the metals under study showed the following hierarchy Cr &gt; As &gt; Pb &gt; Cd. As had a geo-accumulation index of -1.87 to 0.82, Pb, Cd -0.48 to -1.13, and Cr registered -1.28 to -2.45. Ponds in four different regions were found to be safe and suitable for fish culture, however, it was recommended that continuous monitoring of heavy metal concentrations in the aquaculture sector is necessary to mitigate the threat of contamination. Ann. Bangladesh Agric.27(2):105-117

Contaminations evaluation and ecological risk assessment of selected potentially harmful elements in dusts, sediments and soils of Akure, Nigeria

Indiscriminate discharge of waste and high traffic density as well as incessant flooding are major challenges that characterised Akure metropolis. Potentially harmful elements such as Pb, Cd, Ni, Zn are toxins that after exposure may pose a potential lifetime health risk especially to children. This study investigated and traced the contamination levels and the ecological risk of some Potentially-Harmful-Elements (PHEs) (Cu, Zn, Cd, Pb and Ni) in soils, drainage sediments and dusts of the city of Akure, southwestern Nigeria. Composite samples consisting of 40-soils, 30-stream-sediments, 20-road-dust samples and ten representative rock samples were collected for the study. The samples were air dried, pulverized, sieved and digested using aqua regia while the elemental compositions were determined using the ICP-MS. The level of contamination and the ecological risk assessment were determined by comparing with statutory guidelines and calculation of contamination indices, and ecological risk factors. The results (mg/kg) showed that Zn ranged from 13.50 to 384.60; Cu, 3.77 to 99.43; Pb, 13.60 to 69.10; Ni, 2.40 to 27.60 and Cd, 0.02 to 0.31 in sediments. For the soils, Zn ranged from 25.00 to 552.00; Cu, 10.00 to 71.00; Pb, 12.00 to 158.00; Ni, 5.00 to 32.00 and Cd, 0.50 to 1.50 while in dusts, Zn ranged from 118.00 to 876.00; Cu, 35.00 to 148.00; Pb, 52.00 to 487.00; Ni, 9.00 to 23.00; and Cd, 0.50 to 1.40. The concentrations of the analysed PHEs were observed to be elevated in samples from city center characterized by high population and traffic density. The soils, sediments and dusts of Akure metropolis were found to have been moderately contaminated with Cu, Pb, and Zn. The ecological-risk-indices of the three media showed that Ni and Zn were of low to considerable risk, while Cu, Pb and Cd were low to very high risk. The potential ecological risk factor in sediments, soils and dusts was of low to considerable risk, low to high risk and considerable risk to high risk, respectively. The status of the quality of the environmental media requires urgent remediation attention in order to ensure clean and sustainable environment for the city dwellers.

Assessment of heavy metals contamination of agricultural soils using pollution indicators in Thi-Qar governorate, Southern Iraq

This study aims to assess the levels of contamination of agricultural soils with heavy elements (cobalt, copper, iron, nickel, cadmium, and lead) in three regions in Thi-Qar Governorate, Southern Iraq. These three regions are Al-Gharraf, Al-Islah, and Al-Batha. The study was done by using the pollution indicators, which are geographical pollution index (Igeo), contamination degree (Cd), contamination factor (Cf), pollution load index (PLI), potential ecological risk factor (Er), and finally, risk index (RI). From each region, four soil samples were collected from holes 25 cm deep, separated by a distance of 500 meters. After the digestion process of the samples, the concentrations of the studied elements were measured by flam atomic absorption spectrometer (FAAS). The results showed that the average heavy metal concentrations for all samples were (365.810, 96.424, 41.36, 11.919, 5.194 and 0.352 mg/kg). They were in the following order Fe &gt; Ni &gt; Cu &gt;Co &gt; Pb &gt; Cd, respectively. The concentrations of heavy metals in the study areas were all within the limits allowed by the World Health Organization (WHO) except for 8.3% of the studied areas that were beyond the permissible limits for cadmium only. The reason for the increase in cadmium concentrations in some areas could be due to sewage, industrial emissions and agricultural practices. According to the Igeo values, the levels of minerals studied for the three regions followed the following order Cd &gt; Cu &gt; Co &gt; Pb &gt; N i&gt; Fe.

Spatial Variation, Ecological Risk, and Point Sources of Environmental Trace Metals in Lacustrine Ecosystems: An Assessment of Natural and Urban Inputs

ABSTRACT To gain insights into the spatial distribution, ecological risk and origins of heavy metals in surface sediments of lacustrine ecosystems in Cameroon, the content of 7 trace metals (Fe, Cr, Zn, Cu, Ni, Pb and Cd) in sediments from 60 sampling stations in 5 lacustrine environments of different formation contexts. The selected metals were investigated based on inductively coupled plasma mass spectrometry. The results revealed that the average concentrations of Cr, Cu and Cd were higher than the geochemical Threshold values. On the basis of the spatial variation, the studied metals vary quantitatively in the following order: Fe > Cr > Zn > Cu > Ni > Pb > Cd. The calculated enrichment factor (EF) and geo-accumulation index (Igeo) showed that, sediments from large cities and industrial sites had moderate enrichment (3 < EF ≤ 5) and were moderately to severely contaminated (2 < Igeo < 3) while those from low population and rural areas had minor enrichment (1 < EF ≤ 3) and were moderately contaminated (1 < Igeo < 2). With regards to cumulative pollution, the pollution load index (PLI) and the sediment pollution index (SPI) coupled with the potential ecological risk factor (Er) and the potential ecological risk index (RI), the sediments of the lakes are polluted (SPI and PLI > 1) to some extent but with a low ecological risk (Er < 40 and RI < 150). The results of Pearson correlation, principal component analysis (PCA), and cluster analysis (CA) identified three main sources: Ni would have a natural source; Pb from anthropogenic sources, and the other metals (Fe, Cr, Zn, Cu, and Cd) could have a mixed source (anthropogenic and natural). These findings serve as a scientific foundation for the advancement and use of these lake environments, which are the most attractive sites.

Ecological and human health risk assessment of heavy metals in sewage sludge produced in Silesian Voivodeship, Poland: a case study

This study aimed to assess the potential risks posed by heavy metals in sewage sludge (SS) produced by municipal wastewater treatment plants (WWTPs) in the most industrialized region in Poland, the Silesian Voivodeship. The ecological risk was assessed using three indices: the Geoaccumulation Index (Igeo), Potential Ecological Risk Factor (ER), and Risk Assessment Code (RAC), while the health risk was estimated by using carcinogenic and non-carcinogenic risk indices. The average concentrations of metals in the sludge samples were determined revealing that Zn was the predominant element, whereas Cd and Hg were present in the lowest concentrations. The study showed that the processes used in wastewater treatment plants influenced the overall metal content and chemical speciation. According to Igeo values, the dewatered sludge samples exhibited higher contamination levels of Cd and Zn, while Cu and Pb were upon to a lesser extent. The ER values suggest that Cd and Hg present the highest ecological risk. Considering the chemical forms and RAC values, Ni (26.8–37.2%) and Zn (19.8–27.0%) were identified to cause the most significant risks. The non-carcinogenic risk for adults and children was below acceptable levels. However, the carcinogenic risk associated with Ni (WWTP1) for both demographic groups and Cr and Cd (WWTP2), specifically for children, exceeded the acceptable threshold. Ingestion was the primary route of exposure. Although the dewatered SS met the standards for agricultural use, there is still a risk of secondary pollution to the environment and possible adverse health effects.

Estimation of risk to soil and human health during irrigation using ZnO nanoparticles-containing water

This work estimated ecological and human health risks for the exposure pathway of spinach irrigation with metal oxide nanoparticles- contaminated river water. Using literature studies, log-logistic plant uptake models were developed to predict metal uptake in plant parts. Reported or expected values of ZnO nanoparticles (NPs) in surface water were collected from published literature for realistic scenarios and used to estimate the risk to human health in terms of hazard quotient (HQ). Monte Carlo simulation and uncertainty analysis were conducted to assess the variability in the obtained results. The Hazard Quotient (HQ) values obtained at environmental concentrations of ZnO nanoparticles were all below 1 for all age groups. Although the 99th percentile value of HQ was found to be the highest (3.57 ×10−3) for the age group (1−6) years, the probability of HQ value being greater than unity was found to be null for all age groups. The 99th percentile values of contamination factor, potential ecological risk factor, and geo-accumulation index, computed as part of ecological risk assessment, were found to be 0.098, 0.098, and − 0.62, respectively, well within their respective contamination limits. Bio-concentration and translocation factors were also computed to quantify the internal uptake of the plant. The results implied that at the current levels of zinc oxide nanoparticles in surface water, no health risk would be exerted on humans upon spinach consumption under the assumptions used. Also, negligible chances of soil contamination were observed due to zinc accumulation after irrigation. The approach proposed in this work can be used to determine potential health and ecological risks when reusing metal oxide NP-contaminated water for irrigating edible crops. This especially gains significance in a future perspective due to a likely increase in nanoparticles' concentration in the environmental media.

Pollution indices and ecological risk assessment of major elements and trace metals in the marine sediment of the western Nigeria continental shelf, Gulf of Guinea

The Gulf of Guinea is known to be highly productive owing to its ecological and economical significance. Given its importance, detailed evaluation of the major elements (Fe, Mn, Ca, Mg, Na, Al, K and Si) and trace metals (Cu, Zn, Pb, Cr, Ni, As, Sc, V, Th and U) were analyzed from the sediment core within this basin for the first time. This study aims to determine their baseline composition, pollution level, and ecological risk. Analyses of these metals using inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES) with Agilent SPS3 Autosampler showed the descending order of Na > Fe > Ca > Si > Mg > Al > K > Mn and Zn > U > V > Ni > Cr > Th > Pb > As > Cu > Sc for major and trace element respectively. The pollution indices and sediment qualities were assessed using the contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), potential ecological risk factor (Er), modified hazard quotient (mHQ), pollution load index (PLI), ecological risk index (RI), single metal toxic risk index (TRIi) and integrated Toxic risk index (TRI) at three stations (stations A, B, and C). Except for As and U, the mean concentrations of the metals were lower than their respective background values. Based on the pollution indices, the studied trace metals were found to have severe EF (>25) with respect to Zn and V, considerable CF (3 ≤ CF ≤ 6) for As, and high CF (> 6) for U. The Igeo values of all the trace metals indicated unpolluted to moderately polluted status (0 ≤ lgeo ≤ 1). The Er ranges (0.05–41.80) indicate low to moderate ecological risk, while mHQ (< 1) values indicate very low severity of contamination. There was no significant risk from the combined metals recovered from the sediment core of the study area to the marine ecosystems according to RI (<150), PLI (< 1), and TRI (< 5) values. The findings from this study will serve as a preliminary baseline chemical composition for rational ecological protection measures off the Nigerian coast.

Risk evaluation and remedial measures for heavy metal contamination in lagoonal sediments of the Negombo Lagoon, Sri Lanka after the X-Press Pearl maritime disaster

Negombo Lagoon is a vital ecological and socio-economic resource in Sri Lanka that has become susceptible to anthropogenic heavy metal contamination. Therefore, short-core sediment samples from the Negombo Lagoon were analyzed to quantify heavy metal contaminants including both metals (Cr, Ni, Co, Cu, Cd, and Pb) and metalloid As; assess their ecological risk; identify critically polluted regions; and to investigate temporal variation in heavy metal concentration. According to the results, Ni is the most abundant heavy metal in lagoonal sediments. Ni, As, and Cr have severely contaminated the sediments as confirmed by their higher geo-accumulation indices (Igeo) and contamination factors (CF). The degree of contamination (Cdeg) indicated an exceedingly high overall heavy metal contamination, and the pollution load index (PLI) exhibited a prominent site quality decline. Individual potential ecological risk factor (Er) values revealed that Ni, As, and Cd pose a substantial ecological risk. Similarly, the potential ecological risk index (PERI) displayed that heavy metal contamination is a significant peril to this ecosystem. Spatial distributions of the heavy metals are governed mainly by the sediment grain size and freshwater influx. Ni concentration in lagoonal sediments has remarkably increased during the last six years (2016–2022) predominantly due to anthropogenic Ni sources, including the recent X-Press Pearl ship accident. In light of the severe heavy metal contamination in lagoonal sediments, the current study recommends a phytoremediation approach for the Negombo Lagoon.

ECOLOGICAL AND HUMAN HEALTH RISKS ASSESSMENT OF HEAVY METALS IN BOTTOM SEDIMENTS OF THE PŁAWNIOWICE WATER RESERVOIR – ARTIFICIAL LAKE (SILESIAN VOIVODESHIP, POLAND)

This study aimed to assess the ecological and human health risks of heavy metals (Cd, Cr, Cu,Ni, Pb, and Zn) in the bottom sediments of the Pławniowice reservoir, which is located in theSilesian Voivodeship, one of the most polluted regions in Poland. Sediment samples were collectedat 5 sampling points located along the main axis of the reservoir. The concentrations of heavy metalswere determined using Avio 200 ICP-OES atomic absorption spectrometer (PerkinElmer Inc.).The geochemical quality classification, Geoaccumulation Index (Igeo), Ecotoxicological criteria,and Potential Ecological Risk Factor (ER) were used for the assessment of the ecological risk,while for the human health risks, the Hazard Quotient (HQ), Hazard Index (HI), CarcinogenicRisk (CR) and Total Carcinogenic Risk (TCR). The results of the ecological risk analysis indicatedthat among the studied metals, only Cd may pose a potential hazard to the fauna and flora of thereservoir. The results of the health risks assessment indicated that the primary exposure pathwayfor adults and children can be accidental ingestion of polluted sediments. In both cases, childrenare far more exposed to the health effects. Although the studied metals did not pose a direct threatto human health, due to the values of CRs and TCRs to Cd, Cr and Ni it is recommended to takeappropriate steps to reduce the concentrations of these heavy metals in the bottom sediments bytheir periodical removal.

Pollution and health risk assessment of heavy metals in the surface sediments of Timsah Lake, Suez Canal, Egypt

Urbanization and industrial activities around Timsah Lake have led to discharging of pollutants into the lake. The heavy metals pollution level in the lake sediments and implications for living organisms and human health were estimated using several ecological indices. The spatial variations of metals (Cd, Cu, Pb, Mn, Zn, Ni, and Fe) and organic matter content demonstrate that most concentrations increase toward the western part of the lake. The geoaccumulation index (Igeo) arranged the metals as next; Cd > Pb > Zn > Cu > Mn > Fe > Ni, where the lake sediments are extended between moderately-to-extremely contaminated by Cd. Moreover, the contamination factor (CF) for Cd and Pb indicates very high contamination for 100 % of stations and moderate contamination for 58.3 % of the stations, respectively. Spatially, the degree of contamination (Cd) classified lake sediments into three categories; moderately, considerable and very highly contaminated, distributed in the lake's eastern, middle and western parts, respectively. Regarding ecological risk, the potential ecological risk factor (Eri) arranged the metals risks as follows: Cd > Pb > Cu > Ni > Zn, where Cd concentrations suggest high and very high risk for 16.7% and 83.3 % of stations, respectively. The potential ecological risk index (RI) divided lake sediments into moderate, considerable (most of the eastern part), and very high risk (most of the western part). According to sediment quality guidelines (SQGs), Cd values indicate that there have been negative effects on the biota ranging between occasional and frequent. A dermal exposure-based health risk evaluation revealed no non-carcinogenic impact on human health, while Cd indicated a tolerable risk of cancer for children. Moreover, 58.3 and 83.3 % of the stations indicated a tolerable risk of cancer by Ni for adults and children, respectively. The study recommended necessary proactive measures to monitor and manage heavy metal pollution, especially Cd, Pb, and Ni caused by human activities in the Lake.

Lead and lead isotopes as tracers of soil contamination in southwestern Nigeria

The association of soil Pb levels has received considerable attention in recent times in developing countries like Nigeria due to its human health and environmental effect. Unfortunately, the sources of the pollutant has not been resolved for environmental health interest. Therefore, the aim of this study is to trace the sources of Pb contamination using the isotopic composition of Pb in the soil. Thirty (30) soil samples were collected at 0-20 cm depth in 3 different land-use zones, industrial area (IDA, n=10), municipal solid waste facility (MSW, n=10), and traffic section (TRS, n=10). In addition, 3 rock (gneisses) and 3 blacksmith dust samples were collected in the study area for comparison. Properties of the soil such as physico-chemical parameters (pH, organic content, and soil texture) and mineralogical composition were determined to understand the distribution of Pb in the soil of the study area. Similarly, the samples were analyzed for their Pb concentrations and Pb isotopic compositions using inductively coupled plasma mass spectrometry. The soil pH, organic matter, and texture were slightly acidic (4.9-6.9), average organic content (7.9-19.1%), and sandy clay loam in nature, respectively. Therefore, the Pb distribution was enhanced by the physico-chemical parameters. However, the mineral constituent of the soil in order of their abundance include quartz, feldspars, illite-muscovite, kaolinite, Biotite, goethite, and hematite. Consequently, there is no Pb-rich primary mineral in the soil. The environmental assessment of Pb in the study area showed that all the zones were contaminated on the basis of the average contamination factor and geoaccumulation index values. Similarly, the ecological risk factor estimation of Pb showed that the three zones had moderate potential ecological risk factors (41-54). The isotopic compositions of 208Pb/207Pb, and 206Pb/207Pb of the contaminated soil were lower than the corresponding component in gneisses, while the composition of 208Pb/206Pb was higher than the gneisses. Furthermore, the standard plot of (208Pb/207Pb) vs (206Pb/207Pb) showed clearly that the source of Pb in the contaminated soil was mainly from anthropogenic sources.Therefore, from the Pb concentration and isotopic composition acquired, the Pb contamination was mainly sourced from anthropogenic activities from the study area. These sources mainly include scrap metal recycling industry, vehicle emission and domestic and industrial waste. So, more effective remediation strategies need to be developed to reduce the contamination.

Bioaccumulation and distribution of Pb, Ni, Zn and Fe in stinging nettle (Urtica dioica) tissues and heavy metal-contamination assessment in the industrial zone of smelter Ferronikeli (Drenas-Kosovo)

Here, we determined the concentrations of Pb, Ni, Zn and Fe in the soil and in vegetative organs of stinging nettle (Urtica dioica) collected from the banks of the Drenica River in the vicinity of the Ferronikeli smelter. The results were compared with samples collected from the banks 20 km (Shalë village) upriver. In addition, the bioaccumulation factor (BCF) and translocation factor (TF) were determined. Meanwhile, to evaluate the level of pollution in the study area was used the contamination factor (CF), potential ecological risk factor () and the potential ecological risk index (RI). The order of heavy metals according to their concentration in the soil samples at both sampling sites was as follows: Fe > Ni > Zn > Pb. Concentrations in excess of the limits allowed for soils in the samples collected in the vicinity of the smelter were recorded for Pb (173.13 mg kg−1), Zn (1217.48 mg kg−1), and Ni (1443.93 mg kg−1), while at the control site, Zn (270.82 mg kg−1) and Ni (375.47 mg kg−1) were found in excess concentrations. But lead (Pb) level was under allowed limit. The data showed that the stinging nettle is not a hyperaccumulator because BCF < 1 at both sites for all metals under study. Furthermore, analysis of the translocation factor (TFsteam/root) showed that at low of heavy metal concentrations, their mobility was higher (TF > 1). The lowest mobility (TF < 1) was observed at site I (Poklek), where the concentration of heavy metals was higher, except for Fe. The opposite was shown for mobility of metals from stems to leaves (TFleave/steam). The evaluation of CF showed that the area near the Ferronikeli smelter had low degree of Pb, moderate degree of Zn and considerable degree of Ni contamination. The values of RI indicate low potential ecological risk index.

Assessment of heavy metals contamination of sediments and surface waters of Bitter lake, Suez Canal, Egypt: Ecological risks and human health

The concentrations of heavy metals in the surface waters and sediments of Bitter Lake were investigated to assess the level, distribution, and source of pollution and the associated ecological and human health risks. The ecological indices of the lake water indicate low contamination degrees by heavy metals. A dermal exposure-based health risk evaluation revealed no carcinogenic or non-carcinogenic impact on human health. The contamination factor (CF) for Cu, Ni, Pb, Mn, Fe, and Zn (CF < 1) indicate low contamination levels, while Cd reaches very high contamination in most sediment sites (CF ranges from 6.2 to 72.4). Furthermore, the potential ecological risk factor (Eri) and modified hazard quotient (mHQ) indicate low ecological risk for all metals except Cd, revealing high to very high-level ecological risk in most sites (Eri ranges from 185 to 2173 and mHQ from 1.8 to 6.3). This emphasizes the urgency of prompt actions to improve the environment in Bitter Lake.

Ecological assessment of soil contamination by heavy metals affected in the past by the lead–zinc mining and processing complex in Kentau, Kazakhstan

Polymetallic ore processing plants are serious sources of heavy metal pollution. The present study examined the degree of pollution of surface soils with the metals zinc, cadmium, lead, and copper in the single-industry town of Kentau, Kazakhstan, where an enterprise for the processing of lead-zinc ore has been operating for a long time. This enterprise ceased operations in 1994, and this study may be of interest in terms of assessing the current ecological state of urban soils after a 27-year period of possible soil self-cleaning processes. The study showed that the surface soils of Kentau retain fairly high concentrations of metals. The maximum detected concentrations of zinc, cadmium, lead, and copper were 592mg/kg, 1.651mg/kg, 462mg/kg, and 82.5mg/kg, respectively. According to the classification of the geoaccumulation index, the soils of the town belong to pollution classes II, III, and IV with moderate and strong pollution. The calculated potential ecological risk factor indicates that cadmium poses a considerable potential ecological risk, while lead showed a moderate ecological risk. In general, according to the obtained values of potential ecological risk factors, metals can be arranged in the following order: Cd > Pb > Zn > Cu. In this study, a five-step sequential extraction procedure by the method of A. Tessier was used, and the mobility factors of metals were calculated. Based on the data obtained, it was found that cadmium and lead have the highest mobility and, consequently, availability for biota in modern conditions, which may pose a potential risk to public health in the town.

Appraisal of pollution indices due to accumulation of heavy metals in endosulfan affected regions of Kasaragod district, Kerala, India

Present study is an attempt to assess the pollution indices due to the presence of heavy metals in the sediment samples collected from Kodangari stream situated in Enmakaje panchayath, one of the endosulfan spread area of Kasaragod district, Kerala. The concentrations of heavy metals viz., Mn, Zn, Cu, and Fe were measured using Flame Atomic Absorption Spectrometer (FAAS). The pollution indices viz. enrichment factor (EF), contamination factor (CF), geo-accumulation index (Igeo), pollution load index (PLI), Degree of contamination (Cd), Modified degree of contamination (mCd), Potential ecological risk factor (Eri), and index (PERI) were calculated from the heavy metals concentration. The results clearly indicate that the pollution indices associated with heavy metal accumulation does not introduce any harmful effects to the flora and fauna of the study. The results of these systematic investigations are presented and discussed in detail in the manuscript.

GIS-based approach and multivariate statistical analysis for identifying sources of heavy metals in marine sediments from the coast of Hong Kong.

Hong Kong is an urbanized coastal city which experiences substantially different metal loads from anthropogenic activities. This study was aimed at analyzing the spatial distribution and pollution evaluation of ten selected heavy metals (As, Cd, Cr, Cu, Pb, Hg, Ni, Zn, Fe, V) in the coastal sediments of Hong Kong. The distribution of heavy metal pollution in sediments has been analyzed using the geographic information system (GIS) technique, and their pollution degrees, corresponding potential ecological risks and source identifications, have been studied by applying the enrichment factor (EF) analysis, contamination factor (CF) analysis, potential ecological risk index (PEI), and integrated multivariate statistical methods, respectively. Firstly, the GIS technique was used to access the spatial distribution of the heavy metals; the result revealed that pollution trend of these metals was decreased from the inner to the outer coast sites of the studied area. Secondly, combining the EF analysis and CF analysis, we found that the pollution degree of heavy metals followed the order of Cu > Cr > Cd > Zn > Pb > Hg > Ni > Fe > As > V. Thirdly, the PERI calculations showed that Cd, Hg, and Cu were the most potential ecological risk factors compared to other metals. Finally, cluster analysis combined with principal component analysis showed that Cr, Cu, Hg, and Ni might originate from the industrial discharges and shipping activities. V, As, and Fe were mainly derived from the natural origin, whereas Cd, Pb, and Zn were identified from the municipal discharges and industrial wastewater. In conclusion, this work should be helpful in the establishment of strategies for contamination control and optimization of industrial structures in Hong Kong.

Contamination and risk surveillance of potentially toxic elements in different land-use urban soils of Osogbo, Southwestern Nigeria.

The concentrations of potentially toxic elements (PTEs) and their contamination indices were determined in urban soil from five different land-use zones, namely municipal solid waste landfill (MWL), industrial area (INA), heavy traffic area (TRA), residential area with commercial activities (RCA), and farmland (FAL) in Osogbo Metropolis. Ecological and human health risk assessments were also evaluated. Based on the average concentrations, the highest values of As, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were found at INA, while the maximum concentrations of Ba, Cd, and Co were observed at MWL. The average enrichment factor (EF) values of Cd, Cu, Pb, and Zn showed very high to extremely high enrichment in the soils of INA, MWL, TRA, and RCA, while the EF values of Ba, Co, Cr, Fe, Ni, and V were significantly to moderately enriched in the aforementioned land-use zones. This trend was consistent with the average contamination factor (Cf) values of Cd, Cu, Pb, and Zn, which indicated considerable to very high contamination at INA, MWL, TRA, and RCA. However, Cf values of Ba, Co, Cr, Fe, Ni, and V had moderate contamination variously at the different land-use zones. Furthermore, the potential ecological risk factor (Eri) values for all the PTEs were < 40, which indicated low Eri, except for Cd and to some extent Pb. The Eri value of Cd was high to very high at MWL, INA, TRA, and RCA, and low at FAL, while Eri of Pb was only moderate at INA. Assessment of health quotient (HQ) of non-carcinogenic health risks was within acceptable limit (< 1) for most of the PTEs in the different zones for adults and children, except the maximum HQ value of Pb at INA (HQ = 1.0), which was beyond the acceptable limit for children. The carcinogenic risk was within the acceptable limit (1.0 × 10-6) in all the zones, except INA. This may pose health challenges to children in the vicinity of the pollution sources. Continuous monitoring of PTEs to reduce exposure to PTE should be considered.

Contamination, Ecological Risk and Source Apportionment of Heavy Metals in the Surface Sediments in the Hailar River, the Upper Source of the Erguna River between China and Russia

The concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in 17 surface sediment samples from the Hailar River, the upper source of the Ergun River, which is the boundary river between China and Russia, were analyzed. Traceability and cause analysis of heavy metals in sediment were carried out by correlation analysis and principal component analysis. The results showed that the concentrations of Hg and Cd in sediments exceeded the soil background values. Due to the high biological toxicity factor of Hg, Hg is the highest potential ecological risk factor in the Hailar River and its tributary the Yimin River. The sources of Hg and As were likely to come from human activities including mining, coal burning and animal husbandry; other HMs, especially Zn and Cr, mainly come from mining and natural factors. Due to the high level of urbanization and more agricultural activities, the pollution potential of Cd, Hg and Pb in the Yimin River and the lower reaches of the Hailar River was greater. The results of this study will help to understand the distribution and pollution of heavy metals in river sediments in the basin and provide management support for China’s local environmental management departments and relevant national departments of China.