Mean Probable Effect Concentration Quotient Research Articles

Source-risk and uncertainty assessment of trace metals in surface sediments of a human-dominated seaward catchment in eastern China

Current total concentration-based methods for source attribution and risk assessment often overestimate metal risks, thereby impeding the formulation of effective risk management strategies. This study aims to develop a framework for source-specific risk assessment based on metal bioavailability in surface river sediments from a human-dominated seaward catchment in eastern China. Metal bioavailability was quantified using chemical fractionation results, and source apportionment was conducted using the positive matrix factorization (PMF) model. Risk assessment integrated these findings using two indices: the Potential Ecological Risk Index (PERI) and the Mean Probable Effect Concentration Quotient (mPEC-Q), with uncertainty addressed via Monte Carlo simulations. Results indicated that average total concentrations of Cu, Pb, Zn, Cr, Hg, Cd, and As exceeded their respective background levels by 1.63 to 15.00 times. The residual fraction constituted the majority, accounting for 53.84 % to 77.79 % of total concentrations, suggesting significant natural origins. However, source apportionment revealed a predominant contribution from anthropogenic activities, including industrial smelting, agricultural practices, and atmospheric deposition. The contributions were found to vary between 5.35 % and 40.03 % when the total concentration was adjusted to bioavailable content. Total concentration-based PERI/mPEC-Q assessments indicated high/moderate risk levels, decreasing to considerable/low risk levels with bioavailability adjustment. Hg and Cd were identified as priority metals. Further incorporating source appointment parameters into the risk assessment, industrial smelting was identified as the primary contributor, accounting for 66.06 % of total risk by total concentration and 65.63 % by bioavailability. This underscores the role of bioavailability in mitigating risk overestimation. Monte Carlo simulations validated industrial smelting as a major risk contributor. This study emphasizes the importance of considering bioavailability in the source-risk assessment of sediment-metals, crucial for targeted risk management in urbanized catchment areas.

Mogan Gölü’nde (Türkiye) sediment tarama ertesi ağır metallerde ekolojik risk değerlendirmesi

The lake management strategy of sediment dredging (removal) is periodically undertaken in shallow, eutrophic Mogan Lake, an important recreation area. This study aims to use certain indices - enrichment index (EF), contamination/pollution index (CF), degree of contamination (Cd), pollution load index (PLI), geoaccumulation index (Igeo), potential ecological risk index (Eri), integrated ecological risk index (PER), and mean probable effect concentration quotient (mPEC-Q) - to evaluate the state of sediment pollution in the lake after dredging. With this in mind, after dredging was completed, two stations in the littoral zone were selected. Station I was located especially where it would be reached by wastewater from mineral processing facilities and domestic areas; and Station II, where it would be reached by residential and agricultural wastewater. Surface sediment samples were taken repeatedly in May and November 2020 using a sediment grabber. According to the study findings, a) Among the heavy metals studied (Hg, As, Cd, Cr, Pb, Ni, Cu, and Zn), Cu, As, and Cd were found to have the highest enrichment and contamination indices; b) The pollution load index (PLI) values (1.30-2.26) suggest heavy metal pollution in the sediment, and the geoaccumulation index (Igeo) values show intensive Pb contamination at both stations in both months; c) In terms of potential ecological risk index (Eri), Cd was found to have a significant level of ecological risk index; d) The integrated risk index (PER) indicates that all heavy metals in the lake were present at moderate ecological risk levels. Ni and As were metals that had negative biological effects. The results indicate that a) Dredging is not a very effective tool for reducing pollution in the sediment; and b) As long as anthropogenic pollutants continue to enter the lake basin, sediment heavy metal levels should be routinely monitored, particularly those with ecological and biological effects on the sediment: Cu, Cd, Pb, Ni and As. It is predicted that the findings of this study will contribute to the sediment-focused monitoring efforts of organizations and local governments.

Metal pollution assessment in surface sediments of Namak Lake, Iran.

Desiccation of the Namak Lake (NL) can result in the release of fine-grained dust contaminated with heavy metals, while there is little information available on the propagation of metals in the bed sediments of this lake. In this study, contamination of metals in the surface sediments of the NL was analyzed and the pollution status of sediments was assessed using geo-accumulation index (Igeo), enrichment factor (EF), the consensus-based sediment quality guidelines (CBSQGs), and mean probable effect concentration quotient (mPECQ). Results indicated that metal concentrations at the southern part were higher than at the middle and northern parts of the lake. Possible reasons are (i) pollution loads mainly entered the lake through the rivers at the west and northwest, but accumulated at the southern parts, (ii) hard layer of salt covering the bottom of the NL at the northern part suppresses adsorption of metals to the sediment, and (iii) the muddy nature of sediments at the southern part makes it easier for metals to be absorbed. EF results showed that sediments at the southern part of the lake were moderately enriched with lead (Pb). The low Igeo values suggested no pollution with the metals, and CBSQG values showed that the sediments of the NL were not toxic, while the mPECQ index suggested a toxicity probability of less than 25%. Cluster analysis classified the metals into two clusters. In general, the results showed that metal pollution in the surface sediments of NL was generally low although the concentration of Pb at the southern part of the lake was worrisome.

Ecological risk assessment of heavy metal concentrations in sediment and fish of a shallow lake: a case study of Baiyangdian Lake, North China.

The pollution levels of lakes vary in quantity and type of contaminants accumulated in their sediment and water. The second Chinese capital city will be built around Baiyangdian Lake in the near future, and thus, it is important to monitor pollution status of Baiyangdian Lake. This study mainly focused on the accumulated heavy metal concentrations in the surface sediment and in variety of fish bodies. Sediment pollution status and ecological risk were evaluated through geo-accumulation (I-geo), contamination factor (CF), pollution load index (PLI), potential ecological risk ([Formula: see text]), and mean probable effect concentration quotient (mPEC-Q). In addition, human health risks via fish consumption were also evaluated. Based on the results, the average sediment trace As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn concentrations were 9.53, 0.35, 56.37, 32.33, 617.05, 30.18, 19.17, and 84.24mg/kg dry wt, respectively. Both I-geo and [Formula: see text] inferred low pollution levels and low ecological risks from all assessed trace metals except Cd. Cd posed moderate to high ecological risks. Based on sediment quality guidelines (SQGs), average Ni and Cr concentrations exceeded the threshold effect concentrations (TEC), but their [Formula: see text] are low as their average concentrations is below Hebei province pre-contaminations (30.8mg/kg for Ni and 68.3mg/kg for Cr). There is no cumulative toxicity from all the metals through mPEC-Q. Omnivorous fish accumulated statistically insignificantly higher amounts of metals than carnivorous fish, except for Hg. The intake of 12.22g/person/day fish muscle for the entire life is safe from noncarcinogenic human health problems.

Ecotoxicological characteristics and ecological risk assessment of trace elements in the bottom sediments of the Rożnów reservoir (Poland).

The bottom sediments in catchment areas behind dams play a significant role in water ecosystems. On the other hand, the structure of sediments makes them a natural geosorbent, in which pollutants introduced to the aquatic environment accumulate. The use of biotests is recognised as an important approach for the assessment of the quality of bottom sediments, as the chemical analysis of sediment samples alone does not provide evidence of the impact of contaminants on biota. The aim of the study was to apply the chemical and ecological indices to determine the potential risk posed by trace elements in the bottom sediments and to evaluate sediment toxicity using organisms belonging to two taxonomic groups, i.e., plants (Phytotoxkit) and crustaceans (Rapidtoxkit). The 46 sediment samples were taken from the Rożnów Dam Reservoir in Southern Poland. The mean concentration of the trace elements in the sediments was 5.22 mg As; 0.26 mg Cd; 63.23 mg Cr; 28.65 mg Cu; 37.11 mg Ni; 11.15 mg Pb; 69.69 mg Zn and 0.09 mg Hg ∙ kg-1 d.m. The mean probable effect concentration quotient (PECq) value among different sampling sites ranged between 0.04 and 0.33 suggested moderate potential toxicity to the biological communities in bottom sediments. The Ni was potentially the most toxic element for biota in the Rożnów Reservoir. The sensitivity of organisms formed the following order: Thamnocephalus platyurus >Lepidium sativum >Sinapis alba >Sorghum saccharatum. For the plants, the stimulating effect of bottom sediments on root growth was often indicated, while a toxic effect was demonstrated for T. platyurus in 80% of the samples. However, the correlation analysis and PCA results showed that trace elements that originated from similar sources were associated to the toxicity of sediments towards T. platyurus, while ecotoxicity for plants could not be explained by the content of trace elements in bottom sediments. T. platyurus is a good indicator for predicting the toxicity of bottom sediments from the Rożnów Reservoir. However, our study found that both chemical and ecotoxicological analyses are important for a comprehensive evaluation of the quality of bottom sediments.

Fractionation and ecological risk assessment of trace metals in surface sediment from the Huaihe River, Anhui, China

The Huaihe River has suffered increasing pressure from pollutants including metals from anthropogenic activities. In this study, enrichment and fractionation behavior of trace metals were analyzed in sediment samples obtained from fish spawning area of the Huaihe River (Anhui Section) to evaluate the potential ecological risk of trace metals to aquatic organisms. Geochemical indices including enrichment factor and geo-accumulation index as well as mean probable effect concentration quotient and risk assessment code were adopted to assess the contamination degree and potential ecological toxicity. Results showed that the total contents of Cu, Pb, Zn, Cr, Cd, As, and Hg in sediment were 23.1 ± 6.4, 32.3 ± 11.1, 76.8 ± 14.2, 84.6 ± 17.2, 0.2 ± 0.1, 9.0 ± 3.0, and 0.031 ± 0.010 mg/kg, respectively. The indexes EF and Igeo revealed slight accumulation for Pb, Zn, Cr, Cd, and As in some sampling sites. The result of Qm-PEC demonstrated that trace metals in sediment were not toxic to aquatic organisms. Most trace metals appeared to mainly associate with the residual form suggesting lower mobility whereas Cd presented a relative higher exchangeable fraction indicating a great degree of bioavailability. The result of risk assessment code (RAC) evaluation revealed that Cd poses a medium ecological risk for aquatic organisms whereas most of the other trace metals pose low risks.

Heavy Metals in Bottom Sediments of Reservoirs in the Lowland Area of Western Poland: Concentrations, Distribution, Sources and Ecological Risk

The paper presents the results of a study of heavy metals (HMs) concentrations in six retention reservoirs located in the lowland area of western Poland. The objectives of this study were to analyze the Cd, Cr, Cu, Ni, Pb and Zn concentrations, assess contamination and ecological risk, analyze the spatial variability of HM concentrations and identify potential sources and factors determining the concentration and spatial distribution. The bottom sediment pollution by HMs was assessed on the basis of the index of geo-accumulation (Igeo), enrichment factor (EF), pollution load index (PLI) and metal pollution index (MPI). To assess the ecological risk associated with multiple HMs, the mean probable effect concentration (PEC) quotient (Qm-PEC) and the toxic risk index (TRI) were used. In order to determine the similarities and differences between sampling sites in regard to the HM concentration, cluster analysis (CA) was applied. Principal component analysis (PCA) was performed to assess the impact of grain size, total organic matter (TOM) content and sampling site location on HM spatial distribution. Additionally, PCA was used to assess the impact of catchment, reservoir characteristics and hydrological conditions. The values of Igeo, EF, MPI and PLI show that Cd, Cr, Cu, Ni and Pb mainly originate from geogenic sources. In contrast, Zn concentrations come from point sources related to agriculture. The mean PEC quotient (Qm-PEC) and TRI value show that the greatest ecological risk occurred at the inlet to the reservoir and near the dam. The analysis showed that the HMs concentration depends on silt and sand content. However, the Pb, Cu, Cd and Zn concentrations are associated with TOM as well. The relationship between individual HMs and silt was stronger than with TOM. The PCA results indicate that HMs with the exception of Zn originate from geogenic sources—weathering of rock material. However, the Ni concentration may additionally depend on road traffic. The results show that a reservoir with more frequent water exchange has higher HMs concentrations, whereas the Zn concentration in bottom sediments is associated with agricultural point sources.

Tortum Gölü Yüzey Sedimentlerindeki Metal Birikiminin Ekolojik İndeksler Yolu ile Kapsamlı Risk Değerlendirmesi

In this study, ecological risks arising from the accumulation of some heavy metals in surface sediments of Lake Tortum are discussed based on the use of ecological indices, such as enrichment factor (EF), contamination factor (CF), pollution load index (PLI), potential ecological risk index (PER) and the mean probable effect concentration quotient (mPEC-Q). Sediment samples were collected from six different sites using Van Veen grab and heavy metal and organic carbon content of sediments were determined. Results testify to the existence of minimal to moderate contamination in lake sediment. The highest value for the enrichment factor pertains to Cd caused by the use of fossil fuels in settlement areas in the lake catchment. PLI and PER estimations, on the other hand, reveals the presence of low heavy metals-induced ecological risk in lake sediments. Ranging between 15% and 29%, mPEC-Q values are indicative of the fact that Lake Tortum is a low-moderate priority site in terms of toxicity level caused by heavy metals.

Pollution, toxicity, and ecological risk of heavy metals in surface river sediments of a large basin undergoing rapid economic development.

A comprehensive and detailed investigation of heavy metal pollution, toxicity, and ecological risk assessment was conducted for the surface river sediments of the Haihe Basin in China based on 220 sampling sites selected in 2013. The average concentrations of Cr, Cu, Ni, Pb, and Zn in the sediments were 129 mg/kg, 63.4 mg/kg, 36.6 mg/kg, 50.0 mg/kg, and 202 mg/kg, respectively. As indicated by the geoaccumulation and pollution load indices, most surface river sediments of the Haihe Basin were contaminated with the investigated metals, especially in the junction region of the Zi Ya He and Hei Long Gang watersheds. The 5 heavy metals in the sediments all had anthropogenic sources, and the enrichment degrees followed the order Cu > Pb > Zn > Cr > Ni, with mean enrichment factors of 3.27, 2.77, 2.58, 1.81, and 1.44, respectively. According to the mean index of comprehensive potential ecological risk (38.9), the studied sediments of the Haihe Basin showed low potential ecological risk, but the sediments were potentially biologically toxic based on the mean probable effect concentration quotient (0.547), which may be the result of speciation of the 5 metals in the sediments. The results indicate that heavy metal pollution should be considered during the development of ecological restoration strategies in the Haihe Basin. Environ Toxicol Chem 2017;36:1149-1155. © 2016 SETAC.

Spatial distribution of trace elements and ecotoxicity of bottom sediments in Rybnik reservoir, Silesian-Poland.

The aim of study was to integrate chemical analyses and toxicity bioassays in order to assess the environmental risk connected with the presence of trace elements in the sediments. This study examined the ecological significance of trace elements in bottom sediments by applying a set of complementary sediment quality assessment methods sediment quality guidelines (SQGs) (mean probable effect concentration quotient (PECQ)), potential ecological risk index (PERI), contamination degree (Cd) and two bioassays: the bacterial luminescence inhibition test with Vibrio fischeri on sediment elutriates and the direct contact test with the ostracod crustacean Heterocypris incongruens. The samples were collected from 50 stations of Rybnik reservoir. The reservoir is a region with enormous concentration of industry, mainly hard coal mining, electric power industry, and transportation. Despite the high diversity in metal concentration in the sediments, the spatial distribution of trace elements in the sediments was very similar. Moreover, the strong positive correlations between individual pairs of trace elements indicate that they may derive from a similar source and move together. According to mean PECQs, 68 % of the samples were potentially non-toxic and 32 % of the samples were potentially toxic. PERI values suggested that 70 % of the sediment sampling sites exhibited low ecological risk from metal pollution while 24 % of the samples had severe and serious risk. Based on our combined evaluation, we believe that Cd and Cu in the sediment samples frequently caused adverse biological effects. Higher toxic responses were observed in the Microtox test than in the Ostracodtoxkit test. All the sediment samples were found toxic to V. fischeri, and 96 % of the samples had effect percentages >50 %. For H. incongruens, 12 % of the sediments were not toxic and 44 % had effect percentages >50 %. In order to perform a complex assessment of the environmental impact of metal pollution, both chemical and ecotoxicological analysis should be carried out.

Toxic Effects of Organochlorine Pesticides: A Review

This study is aimed at compiling the toxicological aspects of organochlorine compounds (OCCs) including pesticides among different animal models. Tests on animal species like Mean Probable Effect Concentration Quotient (PEC-Q) test, DNA repair assays and histopathological examinations have shown positive results for the toxicity of organochlorine pesticides. The results were observed on different animals including fishes, furseals, frogs, rats, bats and humans. In fishes, endosulfan is found to have acute toxicities. Similarly, organophosphorus, synthetic pyrethroids and microbial insecticides were also found to show their toxic effects. Some compounds such as lambda-cyhalothrin showed a very high toxicity on fish followed by fenvalerate, deltamethrin and cypermethrin. Exposure to OCCs can impart foe cell death by inducing Mitogen Activated Protein Kinase Pathway (MAPK) which is associated with cell growth differentiation and apoptosis. On studying the genotoxic effects of OCCs on germ cells of mouse, it was observed that a lethal mutation can occur just after one mating interval. Increase in the number of micronucleated cells has also been seen after OCC exposure. Neuro-behavioural studies on rats showed the presence of tremors caused by chlordecone and p,p’DDT. Tumorigenicity by organochlorine pesticides is seen to be an epigenetic mechanism in a DNA repair assay. Acute poisoning was seen in liver, kidney and testis of albino rat due to the toxic effect of dursban and DDT. Great declines in populations have been seen due to OCC toxicity in different animal species. Direct and indirect exposure to these compounds should be reduced so as to minimize the possible health hazards.

Influence of ore deposits on river sediment compositions in Dan River drainage, China

We mainly investigated trace element contamination of surface sediments in the Dan River drainage, the source of drinking water for the South to North Water Transfer Project, China, to determine trace element sources and associated levels of risk. Sediment samples were collected at 95 sites along the Dan River in connection with field surveys, and total element concentrations were determined using inductively coupled plasma-mass spectrometry (ICP-MS). Concentrations of most elements were lower than background levels; however, toxic heavy metals, such as As, Cd, Pb, and Sb, showed extremely high concentrations at sites associated with nearby metal ore deposits. Moreover, the spatial variations of contamination by some heavy metals were directly related to the distributions of metal ore deposits in the North and South Qinling terrains; sediment samples with especially high concentrations of Sb and As were from the North Qinling terrain, while sediments with especially high concentrations of Cd and Pb were from the South Qinling terrain, suggesting that metal ore distributions and associated mining activity strongly influence the distribution of heavy metals and heavy metal contamination in the Dan River drainage. Multivariate techniques, including Pearson correlation, hierarchical cluster, and factor analysis, were used to assess the sources of metal contamination. Results indicate that distributions of Al, Ba, Cu, Fe, Mg, Mn, Pb, Sn, Ti, V and Zn are controlled by natural sources; Co and Cr by a combination of geological and anthropogenic inputs; whereas As, Cd, Ni, Sb, and Pb appear to be primarily of anthropogenic origin. The ecological risk associated with heavy metal contamination of sediments was rated as moderate, based on an assessment using geo-accumulation index (Igeo), enrichment factor (EF), potential ecological risk index (RI) and mean probable effect concentration quotient (mPECQ).

Sediment Quality Evolution (2001–2011) in the Ebro River Basin (Spain)

Spatio-temporal variations in sediment quality (20 sample sites) of the Ebro River basin between 2001 and 2011 have been assessed. The self-organizing map classified the sediment samples according to similarities in their chemical compositions. Its powerful visualization tools helped establish the main pollution contribution on each sample. Most of the samples showed low values of the mean-probable effect concentration quotient through time. However, six samples presented several quality issues related to some trace elements or polycyclic aromatic hydrocarbons. Finally, geoaccumulation index values calculated using estimates of background trace element concentrations suggested anthropogenic influences in more than half of the samples.

Potential Risk Assessment of Trace Elements and PAHs in Sediment Samples of the Ebro River Basin (Spain)

This study was carried out in order to assess potential toxicity of hazardous pollutants (8 trace elements and 8 polycyclic aromatic hydrocarbons) in 20 sediment samples of the Ebro River basin (Spain) sampled in 2009. Mean-probable effect concentration quotient (m-PECQ) was found to range from 0.03 to 0.79. Two sites were classified as high priority sites in order to take future remediation actions due to their high m-PECQ value (>0.5). Worst-case scenario in equilibrium partitioning approach showed that acid volatile sulfide (AVS) content was greater than total trace element concentration in all samples. However, 4 sediments were classified as degraded due to the high AVS content measured (>50mmol/kg). Principal component analysis classified the samples according to similar chemical characteristics and revealed that industrial activities are the main source of pollution of the basin.

Potential toxic risk of heavy metals from sediment of the Pearl River in South China

Based on the monitoring of five heavy metal elements in the surface sediments of the Pearl River in South China, potential toxicity of the heavy metals was assessed using consensus-based sediment quality guidelines (SQGs) method and geo-accumulation (I(geo)) index method. The monitoring results showed the heavy metal concentrations were significantly and positively correlated with each other, demonstrating a common trend in variation of concentration in the surface sediments. The assessment using the consensus-based SQGs method showed the potential toxicity of Cu was the highest, and Cd was the lowest. The evaluation based on mean probable effect concentration (PEC) quotient showed the region was seriously polluted with high toxicity heavy metals. Correlation analysis revealed a significant and positive correlation between the mean PEC quotient and the average of I(geo) with a correlation coefficient of 0.926 (n = 23, P < 0.01). In conclusion, the consensus-based SQGs and mean PEC quotient are applicable to assess potential toxicity risks of heavy metals in freshwater sediments in the Pearl River.

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems.

Numerical sediment quality guidelines (SQGs) for freshwater ecosystems have previously been developed using a variety of approaches. Each approach has certain advantages and limitations which influence their application in the sediment quality assessment process. In an effort to focus on the agreement among these various published SQGs, consensus-based SQGs were developed for 28 chemicals of concern in freshwater sediments (i.e., metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides). For each contaminant of concern, two SQGs were developed from the published SQGs, including a threshold effect concentration (TEC) and a probable effect concentration (PEC). The resultant SQGs for each chemical were evaluated for reliability using matching sediment chemistry and toxicity data from field studies conducted throughout the United States. The results of this evaluation indicated that most of the TECs (i.e., 21 of 28) provide an accurate basis for predicting the absence of sediment toxicity. Similarly, most of the PECs (i.e., 16 of 28) provide an accurate basis for predicting sediment toxicity. Mean PEC quotients were calculated to evaluate the combined effects of multiple contaminants in sediment. Results of the evaluation indicate that the incidence of toxicity is highly correlated to the mean PEC quotient (R(2) = 0.98 for 347 samples). It was concluded that the consensus-based SQGs provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems.