Probable Effect Concentration Research Articles

Potentially Harmful Elements Content in Soil and Stream Sediments in Southwestern Districts of Katowice (Southern Poland) – Geochemical Record of Historical Industrial Plants’ Activity

Abstract The aim of the research was to assess the quality of topsoils and stream sediments in the districts of the Katowice City of southern Poland in the Upper Silesian Industrial Agglomeration, influenced primarily by the exploitation of hard coal deposits and metallurgy. The task was carried out using indicators used to assess anthropogenic soil contamination (contamination factor CF and the Igeo geoaccumulation index), as well as ecotoxicological indicators used to determine the quality of stream sediments (Threshold Effect Concentration TEC and Probable Effect Concentration PEC). In order to indicate the most polluted areas, geochemical maps of selected elements in soil and stream sediments were developed. The material comes from the top layer of soil (0.0–0.3 m) and stream sediments located in the districts of the Katowice City. The work took into account selected potentially harmful elements (PHEs). The concentrations of elements were measured using the ICP-AES method, except for Hg (the CV-AAS method). The values of the CF and Igeo indicators allowed for the indication of high concentrations of most metals, arsenic, and sulfur in the topsoil layer, significantly exceeding the geochemical background values caused by the historical exploitation of Zn-Pb and zinc ores and ferrous metallurgy. The values of the TEC and PEC indicators classify the sediments into categories that may threaten the environment and living organisms.

Using Folsomia candida (Collembola) for the ecological assessment of sediment samples from three rivers from the QwaQwa region, South Africa

AbstractSince the establishment of a free economic zone and a simultaneous increase in the population of the QwaQwa region, aquatic systems of the area were expected to undergo an increase in metal contamination. The aims of this study were to assess the quality of sediments from the Metsi-Matsho, Namahadi and Elands Rivers of the QwaQwa region, and to investigate their impact on the survival and reproduction of the collembolan Folsomia candida. Due to the lack of freshwater sediment quality guidelines in South Africa, metal contents of the sediments were analysed and critically interpreted using the national action list for the screening of dredged sediment proposed for marine disposal, and international sediment quality guidelines (SQGs). In the laboratory, F. candida was exposed to 0, 50, 75 and 100% of the sediment samples for 28 days at 20 °C. Sediments were variably contaminated with Cr, with the Namahadi River middle site having the highest concentration (569 mg.kg−1, dry weight) followed by the lower site on the Elands River (529 mg.kg−1, dry weight), both above the recommended prohibition level of 500 mg Cr.kg−1. According to the consensus-based SQGs, only the concentrations of Cr and Ni (upper reach of Metsi-Matsho River) were higher than probable effect concentration, denoting that harmful effects of those metals are likely to occur. Of the two endpoints assessed, reproduction was the most sensitive with the upper reach of the Metsi-Matsho River (half maximal effective concentration, EC50 = 24% sediment) being the most deleterious site to the reproduction of F. candida. Ecotoxicological bioassays using F. candida could be suitable complements to chemical analysis in the assessment of the ecological risks of freshwater sediments as this collembolan species is sensitive to sediments with variable ranges of metal contamination.

Potentially toxic elements in sediments near mines-a comprehensive approach for the assessment of pollution status and associated risk for the surface water environment.

This research is focused on the assessment of the pollution status of river and lake sediments near Pb, Zn, and Cu mines and tailings in the southeastern part of Serbia-Krajište area. The study is based on hypothesis that investigated rivers and lakes in the Krajište area could be polluted by potentially toxic elements (PTEs) and that these elements could pose considerable ecological risk to the studied surface water environment. High PTE contents are detected in studied river sediments (up to 7892mgkg-1 for Zn, 3224mgkg-1 for Cu, 36,790mgkg-1 for Pb, 64.2mgkg-1 for Cd, and 1444mgkg-1 for As). Given that the contents of the studied elements in most of the river sediments exceeded the background values, values prescribed by regulations of the Republic of Serbia, as well as probable effect concentration (PEL), it is possible to conclude that sediments were heavily polluted and that detrimental effects can be expected. Contamination indices including the enrichment factor (EF), contamination factor (CF), index of geoaccumulation (Igeo), potential ecological risk index (Eri), ecological risk index (RI), pollution load index (PLI), and aggregative toxicity index (ATI) were used to assess the degree of pollution by PTEs. The ecological risk assessment revealed that there is a significant risk observed for toxic elements (primarily Pb, Cu, Cd, and As) at this moment. The highest contamination indices (EF, Igeo, CF, PLI, and ATI) are mainly associated with historical and current mining activities. The Monte Carlo analysis based on the risk assessment indices was used to evaluate the uncertainty. The most pronounced toxic risk is found for the Pb, Cu, Cd, and As which assessment was in the range of high and extremely high-risk probabilities. The obtained results suggest that levels of toxic elements pose a significant ecological risk to the surface water environment near Pb, Zn, and Cu mines in the Krajište area. The methodology applied in this paper could be very useful for other researchers dealing with the problem of environmental pollution by toxic elements.

Source apportionment and source-specific risk assessment of bioavailable metals in river sediments of an anthropogenically influenced watershed in China

Integrated source analysis and risk assessment of metals facilitate the development of targeted risk management strategies. However, previous studies usually addressed total concentration rather than bioavailability, and consequently overestimated metal risk, especially natural source-related risk. In this study, a source-specific risk assessment was conducted by integrating the source analysis of bioavailable metals in surface sediments. Moreover, risk assessment was performed using two bioavailability-based indices: the total availability risk index (TARI) and a modified index of mean probable effect concentration quotients (mPEC-Q). A representative river watershed in eastern China was selected as the study area. Findings revealed that the total concentrations of Pb, Cu, Zn, Cr, and Ni in the sediments were 1.4–2.2 times higher than the local soil background values. Using a modified community bureau of reference (BCR) sequential extraction procedure, the dominant fraction for Pb, Cu, Zn, and Cr in the studied area was found to be the residual fraction, constituting 53.63–62.44% of the total concentrations. This suggested that a significant portion of the metals potentially originated from natural sources. Nevertheless, the concentration enrichment ratio (CER) indicated that anthropogenic sources contributed significantly, accounting for 67.84–87.68% of bioavailable metals. The positive matrix factorization (PMF) model further identified three different sources of bioavailable metals, with a descending concentration contribution sequence of industrial sources (37.61%), mixed traffic and natural sources (33.17%), and agricultural sources (29.22%). Both the TARI and mPEC-Q index values indicated that the bioavailable metals generally posed a moderate risk, and Ni was the priority pollutant. Industrial sources contributed the most to the total risk, although the contribution from TARI-based assessment (37.27%) was lower than that from the mPEC-Q assessment (46.43%). This study provides an example of the consideration of metal bioavailability in the context of source-specific risk assessments to develop more reasonable management strategies.

Receptor model-based source apportionment and ecological risk assessment of metals in sediment of river Ganga, India

Ganga river surface sediment was sampled from 11 locations, which revealed average concentrations (mg/kg) of metals in the order Mn (296.93) > Zn (61.94) > Cr (54.82) > Cu (30.19) > Pb (24.42) > Cd (0.36). Sediment quality guidelines showed metals rarely to occasionally exhibit adverse biological effects. Indices like potential ecological risk, contamination security index, hazard quotients, multiple probable effect concentrations quality, mean probable effects level quotients, mean effects range median quotient suggest nil to a very low level of pollution with low ecological risk. Contamination factor, geo accumulation index, enrichment factor, quantification of contamination revealed that Pb and Cd originated from anthropogenic activities. APCS-MLR model revealed that metals contributed from natural sources (Zn, Mn, Cr; 20.18 %), industrial-agricultural (Cd; 21.35 %); and discharge of paints, Pb batteries, fossil fuel (Pb; 8.49 %). Present findings will serve as an effective guideline for managing and ameliorating pollution in the river system.

Heavy Metal Contamination and Potential Ecological Risk Assessment in Sediments of Lake Bafa (Turkey)

This study examined the spatio-temporality of heavy metal concentrations (Al, Cd, Co, Cr, Fe, Mn, Ni, Pb and Zn) in the sediments of Lake Bafa, one of the most important wetlands of Turkey’s Aegean region. The study evaluated sediment quality according to threshold effect concentration (TEC) and probable effect concentration (PEC) values based on sediment quality guidelines (SQG), and provided a potential ecological risk assessment (PERI) along with indices such as geoaccumulation index (NIgeo), enrichment factor (EF), contamination factor (CF), and pollution load index (PLI). For this purpose, surface sediment from 10 different points and core samples from three different points were seasonally collected and the concentrations of nine heavy metals were determined by ICP-MS. The findings indicated the following accumulation order of heavy metals in the sediment: Fe > Al > Mn > Ni > Cr > Zn > Pb > Co > Cd, with concentrations of Al, Mn, and Ni being high in the surface sediment samples. According to the NIgeo, surface sediment and core samples were very slightly polluted with Cr, Mn, and Co at most stations, while five stations were slightly polluted with Cd. Regarding EF, the lake was at risk in terms of Al and Pb accumulation. The CF results indicated that the lake was under pressure in terms of heavy metal pollution. The PLI results indicated a significant pollution hazard at all stations, while the PERI analysis indicated moderate risk of heavy metal pollution at some stations. As one of the most comprehensive studies applying such indices to Lake Bafa, the results are very significant in terms of evaluating the lake’s ecological sustainability.

Particle-based nutrients and metal contaminants in the habitat of Unionidae mussels in the Tisza River (Hungary)

Introduction:Unioniade is a species-rich family of freshwater mussels with an almost worldwide distribution. In Central European rivers Unio crassus, Unio tumidus and Unio pictorum have relatively high populations. In order to characterize the habitats of these suspension feeders, their nutrient supply and potential metal contaminants were investigated in near-bottom suspended (NBS) sediments and bottom sediments (BS) collected at four sampling locations along the Tisza River.Methods: The grain size distribution of sediments was determined by laser-diffraction technique. The total organic carbon (TOC) and the total Kjeldahl nitrogen (TN) were measured by a TOC analyzer and automated colorimetry, respectively. The phosphorous and metal concentrations were determined by inductively coupled plasma mass spectrometry following a microwave assisted acidic extraction of sediments with aqua regia.Results: The NBS sediments contained smaller grains than the BS samples, with roughly 85%–90% of the particles being less than 60 μm, allowing these mussels to catch them. Contrarily, only 2.47%–51.8% of BS samples were less than 60 μm. The NBS sediments contained 30, 23, and 15% more organic carbon, nitrogen, and phosphorous, respectively, than the BS samples. The rounded C:N:P molar ratios in the NBS sediments were 60:4:1, whereas they were 45:3:1 in the bottom sediments. The concentration of metals was also greater in the NBS sediments with the exception of Zn at Tokaj and Fe, Al, Mn, and Cr at Szeged, where prior contaminations transported by the tributaries Bodrog and Maros are stored in the top 10 cm of BS.Discussion: On basis of the measured C:N:P molar ratios it can be stated that soil-derived organic materials are the main sources of the nutrient elements in the habitats of suspension feeders in the Tisza River. The finer NBS sediments have higher specific surface area than the BS and thereby contain more biofilms on the grains resulting in higher proportion of organic nutrients and metal ions bounded as complexes or chelates. Comparing the measured metal concentrations of sediments with the concentration limits summarized in the Consensus-Based Sediment Quality Guidelines developed for evaluation of potential risk of metal contaminants in sediments for the benthic-dwelling organisms, it can be established that only the Hg concentration exceeded the probable effect concentration.

Distribution and biodegradation potential of polycyclic aromatic hydrocarbons (PAHs) accumulated in media of a stormwater bioretention

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds that can be captured and accumulate in the bioretention cell media, which may lead to secondary pollution and ecological risks. This research aimed to understand the spatial distribution of 16 priority PAHs in bioretention media, identify their sources, evaluate their ecological impact, and assess the potential for their aerobic biodegradation. The highest total PAH concentration (25.5 ± 1.7 μg/g) was observed 1.83 m from the inlet and 10–15 cm deep. The individual PAHs with the highest concentrations were benzo [g,h,i]perylene in February (1.8 ± 0.8 μg/g) and pyrene in June (1.8 ± 0.8 μg/g). Data indicated that primary sources of PAHs were fossil fuel combustion and petroleum. The ecological impact and toxicity of the media were assessed by probable effect concentrations (PECs) and benzo [a]pyrene total toxicity equivalent (BaP-TEQ). The results showed that the concentrations of pyrene and chrysene exceeded the PECs, and the average BaP-TEQ was 1.64 μg/g, primarily caused by benzo [a]pyrene. The functional gene (C12O) of PAH-ring cleaving dioxygenases (PAH-RCD) was present in the surface media, which indicated that aerobic biodegradation of PAHs was possible. Overall, this study revealed the PAHs accumulated most at medium distance and depth, where biodegradation may be limited. Thus, the accumulation of PAHs below the surface of the bioretention cell may need to be considered during long-term operation and maintenance.

Spatial variability and ecological risk assessment of heavy metals in surface sediments of the Unete River in the department of Casanare (Colombia)

Surface sediment samples obtained from 46 sites of the Unete River in Casanare (Colombia) were analyzed to evaluate the concentrations of the heavy metals As, Cu, Ni, Pb and Zn as well as to determine their geographic spatial distribution and potential ecological risk. The measured concentrations were compared with the background values (BV), threshold effect concentration (TEC) and probable effect concentration (PEC) from consensus-based Sediment quality criteria guidelines (SQGs) for heavy metals in freshwater ecosystems in order to determine the level of concern of the contaminant concentrations. Based on these results and on the indices of determined potential ecological risk, As and Pb were shown to be the heavy metal contaminants of most concern in surface sediments. The possible sources causing the concerning concentrations were then discussed.

Contamination and risk assessment of trace metals and As in surface sediments from abandoned gold mining sites of Bekao, Adamawa-Cameroon

This paper assesses the spatial distribution and the trace metal and As contamination in surface sediments along the Lom River in the abandoned gold mining sites of Bekao (Adamawa Cameroon). A total of thirty one (31) surface sediment samples is collected and analyzed to determine the concentrations of Cr, Mn, Fe, Ni, Cu, Zn, Sn, Pb and As. The results obtained are compared with the Average Shale Values (ASVs) and Sediment Quality Guidelines (SQGs) as the threshold effect concentration (TEC), the probable effect concentration (PEC), the Effect Range Low (ERL) and the Effect Range Median (ERM). To assess the trace metal and As pollution level in sediments, nine environmental pollution indices, namely geoaccumulation index (Igeo), enrichment factor EF, contamination factor (CF), contamination degree CD, modified degree of contamination (mCD), Nemerow index (NI), contamination severity index (CSI), probability of toxicity (MERMQ) and potential ecological risk RI are used. In addition, Pearson’s correlation matrix and General Linear Model (GLM) are used to determine the pollution indices which adjust better with the trace metals and As concentrations. The results reveal that the sequence of trace metals and As mean concentrations was Fe ¿ Mn ¿ Cu ¿ Ni ¿ Sn ¿ Cr ¿ Zn ¿ Pb ¿ As, and the mean concentrations of Zn, Ni, Sn, and Cu exceed the ASVs. Based on the sediments quality guidelines (SQGs), sediments are polluted in Ni and Cu. According to the Igeo, EF and CF, Sn and Cu reveal a high level of contamination with significant enrichment and Ni a moderate level of contamination and enrichment. The results of the calculation of CD, mCD, and NI indices suggest significant contamination, high contamination and high pollution of trace metals and As in sediments, respectively. Globally, CSI demonstrates an ultra-high severity contamination, MERMQ a high-medium priority with a toxic probability of 49% and RI show a moderate ecological risk. Pearson’s correlation matrix and GLM suggest that CSI and MERMQ are the indices which adjust better with trace metals and As in sediments.

Sediment Heavy Metal Pollution Assessment in Changwang and Wuyuan Rivers in Hainan Island, China

Heavy metal pollution may pose a significant threat to aquatic ecosystems. To assess heavy metal pollution, sediment samples were collected from Changwang and Wuyuan Rivers between June and December 2019. An inductively coupled plasma mass spectrometer was used to analyze the concentrations of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn. The results revealed that Changwang River had significantly high concentrations of Cr (240.70 mg kg−1), Co (36.02 mg kg−1), Ni (108.70 mg kg−1), and Cu (36.61 mg kg−1), whereas As (7.55 mg kg−1) was elevated in Wuyuan River. In addition, Cd, As, Pb and Zn concentrations were below China’s sediment quality standard limits (GB 3838-2002), but the Cr level exceeded the limit. However, Cr and Ni exceeded the probable effect concentrations (PEC) and thus may cause toxic effects. The contamination factor, geo-accumulation index, and modified degree of contamination revealed that Changwang experienced considerable to very high heavy metal pollution, while Wuyuan had low to moderate pollution. The pollution load index demonstrated that the rivers were polluted during all seasons. Additionally, the risk index showed considerable and moderate risks in Changwang and Wuyuan, respectively. The metal ecological risk was ranked as Cd > Ni > As > Co > Cu > Cr > Mn > Pb > Zn. Multivariate analyses categorized heavy metals into two groups based on their potential sources: group one included Cr, Co, Ni, Cu, Mn, and Zn, while group two contained As, Cd, and Pb. The study provides valuable data on heavy metal pollution, which needs improvement for the studied rivers. The data can be used to assess pollution risks and manage riverine sediment quality.

Risk assessment and source apportionment for metals in sediments of Kaptai Lake in Bangladesh using individual and synergistic indices and a receptor model

Metal enrichment in lake sediments originating from multiple sources can threaten both the aquatic ecosystem and human health. Therefore, assessment of the eco-environmental risks and potential sources of metals in the sediments is essential for effective lake management. Here, we analyzed the sediment metal contents of Kaptai Lake, the largest lake in Bangladesh for the first time with this study. The results indicated that only Cr and Ni contents among the metals studied exceeded the probable effect concentrations (PEC) at 25.42 % and 55.93 % of the sampling stations, respectively. All metals at most sampling stations showed low contamination and low ecological risk based on the individual indices (geoaccumulation index, contamination factor, ecological risk factor, enrichment factor and modified hazard quotient). There was no significant risk from the combined metals in the sediments of the lake according to the synergistic indices (toxic risk index, Nemerow risk index, ecological risk index, Nemerow pollution index and pollution load index). Organic matter and silt were significant sediment parameters that favored the accumulation of Cr, Fe, Cu, Pb and Mn. In the absolute principle component scores-multiple linear regression model (APCS-MLR), five potential sources of metals were identified in the sediments: Zn, Mn, Co and Cd mainly from natural sources and to a lesser extent from agricultural and aquacultural activities, Ni, Cr and Fe from parent materials, Pb and Cu mainly from natural sources and to a lesser extent from vehicle emissions, Hg and U from lithogenic sources, and As from natural sources. This study will improve our knowledge of the sedimentary metal contents of Kaptai Lake and provide helpful information for developing effective lake management and pollution control strategies.

Effect of past century mining activities on sediment properties and toxicity to freshwater organisms in northern Sweden

The release of toxic metals from local mining activities often represents a severe environmental hazard for nearby lake ecosystems. Previous studies on the impact of mining have primarily focused on single lakes, with less emphasis on spatial and temporal recovery patterns of multiple lakes within the same catchment, but with different hydrological connection and distance to the pollutant source. This knowledge gap prevents us from assessing the real environmental risk of abandoned mines and understanding ecosystem recovery. This study explores the intensity and spatial patterns of sediment contamination and the potential for ecosystem recovery in three lakes in close vicinity of a lead (Pb) and zinc (Zn) mine in Sweden that has been inoperative for >20 years. Dated (210Pb and 137Cs) sediment cores from each lake were used to reconstruct temporal patterns in trace element deposition and relate those with past mining activities. Results show that all lakes were affected by mining, indicated by increasing Pb and Zn concentrations and decreasing organic matter content, at the onset of mining. However, the extent and timing of mining impact differed between lakes, which was partly ascribed to differences in the historical use of tailings and settling ponds. Assessment of toxicity levels in sediments, based on normalized Probable Effect Concentration Quotient (PEC-Q) to organic matter content, provided more consistent results with the historical mining than conventional methods, showing a decreasing impact in lakes once the operations ceased. Still, sediment Pb concentrations were > 10 times higher than pre-mining values, evidencing the urgent need for remediation actions in the study lakes. This study highlights the importance of considering spatial heterogeneity in metal deposition, sediment organic matter content, and hydrological connectivity with tailings when risk assessments are performed in mining-impacted lakes. The use of normalized PEC-Q in toxic assessments is also recommended.

Heavy metals assessment of ecosystem polluted with wastewaters and taxonomic profiling of multi-resistant bacteria with potential for petroleum hydrocarbon catabolism in nitrogen-limiting medium.

The coexistence of heavy metals (HMs) and petroleum hydrocarbons (PHs) exacerbates ecotoxicity and impair the drivers of eco-functionalities that stimulate essential nutrients for the productivity of the impacted environment. Profiling the bacteria that stem the ecological impact via HMs sequestration and PHs catabolism with nitrogen fixation is imperative to bioremediation of the polluted sites. The sediment of site that was consistently contaminated with industrial wastewaters was analysed for ecological toxicants and the bacterial strains that combined HMs resistance with PHs catabolism in a nitrogen-limiting system were isolated from the sediment and characterized. The geochemistry of the samples revealed the co-occurrence of the above-benchmark concentrations of HMs with the derivatives of hydrocarbons. Notwithstanding, nickel and mercury (with 5% each of the total metal concentrations in the polluted site) exhibited probable effect concentrations on the biota and thus hazardous to the ecosystem. Approx. 31% of the bacterial community, comprising unclassified Planococcaceae, unclassified Bradyrhizobiaceae, Rhodococcus, and Bacillus species, resisted 160µmol Hg2+ in the nitrogen-limiting system within 24h post-inoculation. The bacterial strains adopt volatilization, and sometimes in combination with adsorption/bioaccumulation strategies to sequester Hg2+ toxicity while utilizing PHs as sources of carbon and energy. Efficient metabolism of petroleum biomarkers (> 87%) and Hg2+ sequestration (≥ 75% of 40µmol Hg2+) displayed by the selected bacterial strains portend the potential applicability of the bacilli for biotechnological restoration of the polluted site.

Determination of pollution status of Nilüfer river by water and bottom sediment analysis

Abstract This study aims to evaluate the Nilüfer river in terms of water quality standards. Bottom sediment and water samples were taken from six different locations. The analysis of the physicochemical parameters of water compared with FAO for irrigation water quality standards. In addition, the SAR (sodium adsorption ratio), % Na, MAR (magnesium adsorption ratio), RSC (residual sodium carbonate), KR (Kelley's ratio) and % PI (permeability index) parameters were evaluated in water samples. The bottom sediment pollution situation was evaluated in terms of pollution index such as TEC (threshold effect concentration) and PEC (probable effect concentration). According to the results of the study, the irrigation water classes of the samples were determined as C2S1 and C3S1. Especially, sample sites S4, S5 and S6 were not suitable for irrigation in terms of RSC, KR. The bottom sediment exceeded the TEC and PEC limit values in terms of Zn, Cu, Cr and Ni contents. This may cause adverse effects on the majority of sediment-dwelling organisms.The use of alternative water sources should be preferred. The river can be used for irrigation with precaution but extensive treatment is required before use for irrigation purposes to prevent adverse public health effects.

Source-oriented risks apportionment of toxic metals in river sediments of Bangladesh: a national wide application of PMF model and pollution indices.

Intense human activities, particularly industrial and agricultural output, has enriched metal(loid)s in riverine sediment and endangered aquatic ecosystems and human health. Promoting proper river management requires an assessment of the possible ecological hazards and pollution posed by metal(loid)s in sediments. However, there are limited large-scale risk assessments of metal(loid)s contamination in riverine sediment in heavily populated nations like Bangladesh. This study compiled data on sediment metal(loid)s, for example, Cd, As, Cu, Ni, Cr, Pb, Mn, and Zn, from 24 major rivers located across Bangladesh between 2011 and 2022 and applied positive matrix factorization (PMF) to identify the critical metal(loid)s sources and PMF model-based ecological risks. Based on studied metal(loid)s, 12-78% of rivers posed higher contents than the upper continental crust and 8% of the river sediments for Cr and Ni, whereas 4% for Cd and As exceeded probable effect concentration. Cr and Ni in the sum of toxic units (STU), whereas Mn, As and Cd in potential ecological risk (PER) posed the highest contribution to contaminate sediments. In the studied rivers, sediment contaminant Mn derived from natural sources; Zn and Ni originated from mixed sources; Cr and Cu were released from the tannery and industrial emissions and Cd originated from agricultural practices. Source-based PER and NIRI indicated that mixed source (4% rivers) and tannery and industrial emission (4% rivers) posed very high risks in sediments. For the creation of macroscale policies and the restoration of contaminated rivers, our national-scale comprehensive study offers helpful references.

Bioaccumulation and Biota-Sediment Accumulation Factor of Metals and Metalloids in Edible Fish: A Systematic Review in Ethiopian Surface Waters.

Metals and metalloids pollution of Ethiopian surface water is becoming an environmental issue. Bioaccumulation and Biota-Sediment Accumulation Factor (BAF and BSAF) are used to quantify the bioaccumulation of contaminants from water and sediment to biota. The present study aimed to determine the BAF and BSAF of metals and metalloids in different surface waters of Ethiopia. Furthermore, the ecological and human health risks were also examined. Generally, 902 peer-reviewed papers from 2005 to 2022 were searched using search engines. The most common types of edible fish species in studied surface waters of Ethiopia were Oreochromis niloticus, Clarias gariepinus, and Barbus intermedius. The concentration of metals and metalloids were higher in sediment than in water and in carnivorous fish than in herbivorous fish. The BSAF of Se in all fish species was greater than 1. Oreochromis niloticus was a bio-concentrator of As and Se. The dissolved concentration of Cu, Cd, Pb, and Ni were higher compared to the Ethiopian Environmental Protection Authority and the European Union; Organization of Economic and Co-Operation Development environmental water quality standard guidelines for inland surface freshwater bodies. Likewise, in sediment, the concentration of Cu, Pb, Ni, Zn, and Cr were above Tolerable Effect Concentration values and Cd, Ni, and Cr were above Probable Effect Concentration levels when compared to the United States Consensus-Based Sediment Quality Guidelines for freshwater which indicates that these metals may pose risk to aquatic organisms. Consumption of raw water and fish contaminated with the detected metals and metalloids is not associated with any diseases. However, local consumers who live close to each freshwater ecosystem may become more exposed to health risk hazards. The findings of this study will provide baseline information on BAF and BSAF of metals and metalloids in surface waters and will contribute to the effective monitoring of environmental quality.

Assessment of the global toxicity of marine sediments from the Dakar peninsula (Senegal, West Africa)

Marine pollution in West Africa is major threat particularly around coastal megacities. We assess the chemical and ecotoxicological quality of the marine sediments in various submerged sampling sites of Dakar. Analysis revealed that sediments were slightly basic in which fine and coarse sands predominated. High percentages of total organic carbon were found sometime above6%. Higher levels of heavy metal were reported than in previous studies. Chromium and nickel were above the Probable Effect Concentration. Low trophic level appeared not affected by the overall toxicity, while medium trophiclevel was more affected. Indeed, the vast majority (91%) of sites studied revealed a net percentage of Magallana gigas embryolarval developmental abnormality over 20%. The assessment of the global toxicity of marine sediments from the Dakar sites Studied(n = 11) seemed, almost, as a whole, to be in a poor ecotoxicological state calling to take measures to improve the sanitary condition of this marine feature.

Sediment-associated heavy metal contamination and potential ecological risk along an urban river in South Africa

Sediment contamination by heavy metals poses one of the worst environmental risks to aquatic ecosystems worldwide. The study explored sediment-associated heavy metal contamination and potential ecological risk along the Molopo River in Mahikeng, South Africa. Total concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) were analysed using inductively coupled plasma mass spectrometry. Various indices were applied to assess the level of contamination and ecological risk. Most heavy metal concentrations at selected upstream and downstream sites were below average shale, except Cr, Cu, Hg, Pb, and Zn. The contamination factor (CF) indicates that the level of contamination was low (CF < 1) at most sampling sites, except Cr, Cu, Pb and Zn, which varied from moderate (1 CF < 3) to considerable (3 ≤ CF < 6) contamination. The enrichment factor (EF) shows that Cd, Cr, Cu, and Zn were moderate (2 EF < 5) to significantly enriched (5 EF < 20) at the affected sites. The results suggest anthropogenic enrichment (EF > 2) of Cd, Cr, Cu, and Zn. The threshold effect concentration and probable effect concentration sediment quality guidelines predicted that Cr, Cu, and Ni concentrations were more likely to have harmful effects on bottom-dwelling organisms. Pearson correlation and principal component analysis reveal that Cd, Cr, Cu, Ni, Pb, and Zn had a common anthropogenic source. We attribute the source to industrial and wastewater effluent, vehicle traffic, and runoff from various urban surfaces in the city. The study provides baseline data for heavy metal monitoring in the study area. Future research and monitoring should focus on heavy metals that cause concern because of their concentrations (Cr, Cu, Pb, and Zn) and potential ecological risk (Cr, Cu, and Ni).

Spatial Distribution and Ecological Risk Assessment of Heavy Metals in the Sediment of a Tropical Mangrove Wetland on Hainan Island, China

Mangroves have a high ecological service value and play an important role in achieving carbon neutrality. However, mangrove wetland soil quality is constantly being affected, and the ecological services provided are gradually declining due to the threat of various pollutants, especially heavy metal pollution. Exploring the sources and ecological risks of heavy metals in mangrove sediments will be helpful in improving mangrove protection. In 2020, sediments were collected from terrestrial and aquatic areas of Dongzhai Harbor mangrove wetland in Hainan, China, and were analyzed for the concentrations of nine heavy metals (As, Cd, Cr, Cu, Hg, Pb, Ni, Zn, Co). The results showed that there were obvious spatial distributions of heavy metals in sediments. The high concentrations of heavy metals occurred largely in terrestrial areas and in 0–20 cm of the sediment surface layer. Correlation analysis and cluster analysis indicated that As mainly originated from ships and aquaculture in the harbor waters, Cd and Hg from agriculture, Cr, Cu, Ni, Zn and Co from the weathering of parent rocks, and Pb from soot emitted from metal smelters and automobile exhaust. The individual potential ecological risk index (Eir) indicated that contaminating elements were mainly Cd and Hg. The potential ecological risk index (RI) and multiple probable effect concentrations quality (mPECQs) indicated that the areas with high heavy metal concentration and the 0–20 cm range of sediment surface layer were more susceptible to heavy metal contamination. Although there were no obvious ecological risks in the area, these results could facilitate the understanding of the distribution of heavy metal pollution in mangroves and provide information to achieve sustainable development of mangroves.