Consensus-based Sediment Quality Guidelines Research Articles

Leachate Characterization and Assessment of Soil Pollution Near Some Municipal Solid Waste Transfer Stations in Baghdad City

This study is conducted to determine the extent to which transfer stations in the Karkh neighborhood of Baghdad, Iraq, contribute to physicochemical and heavy-metal contamination of the soils in the immediate area. The concentrations of physicochemical primary indicators (pH, OC, OM, Ca+2, Mg+2, Na+1, NO3-1, Cl-1, SO4-2) and heavy metals (Pb, Cd, and Cu) were measured during July 2022 at four investigation sites that were located at distances of 5 m (Site 1), 10 m (Site 2), 15 m (Site 3), and 20 m (Site 4) from the edges of the mentioned transfer stations (Al-Rasheed, Al-Mansour, Al-Shula, and Al-Dora). The concentrations of the physico-chemicals and heavy metals were compared to the standards of the Food and Agriculture Organization (FAO) and the Consensus-Based Sediment Quality Guidelines (CBSQG). Based on the data collected, it was determined that Site 1 had the greatest physico-chemical and heavy metal concentrations, whereas Site 4 had the lowest. The metals tested were found to accumulate in the following order: Cu > Pb > Cd. Additionally, it was noticed that all the measured concentrations of metals were higher than the limitations of the CBSQG. The presence of Ca+2, Mg+2, Na+1, Pb, Cd, and Cu in soil suggests that leachate percolation is having a major impact on the soil.

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.

Source Identification and Ecological Risk of Potentially Harmful Trace Elements in Lacustrine Sediments from the Middle and Lower Reaches of Huaihe River

Sediment pollution caused by potentially harmful trace elements (PHTEs) has attracted a great deal of attention, due to the persistent risks it poses to human beings and ecosystems. However, the pollution status and source identification of PHTEs from the middle and lower reaches of Huaihe River remains unclear. In this study, arsenic, cadmium, chromium, copper, nickel, zinc, lead and isotopic ratios in the lacustrine sediments of this river are investigated to determine the source of, and ecological risk posed by, these PHTEs. The results show that the concentrations of chromium, copper, nickel and zinc are generally close to the background values in the lacustrine sediments, and are assessed as representing a low degree of contamination. By contrast, significantly higher concentrations of arsenic and cadmium are commonly measured in the upper sediments, which are mainly derived from the agricultural application of fertilizers, pesticides and wastewater. Meanwhile, possible atmospheric lead deposition is identified by the isotopic analysis. Among these PHTEs, adverse biological effects of arsenic, chromium, and nickel may occur in lakes according to consensus-based sediment quality guidelines, but cadmium is selected as a PHTE for priority control according to potential ecological risk index. Our study highlights that developing regional sediment quality guidelines and soil restoration in the catchment are crucial for the freshwater ecosystem in the middle and lower reaches of Huaihe River.

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.

Ecological risk assessment and phytomanagement of trace metals in the sediments of mangroves associated with the Ramsar sites of Kerala, southern India.

The study investigated trace metal accumulation in the sediments of three major mangrove ecosystems associated with the Ramsar sites of Kerala state, the ecological risks they pose, and the absorption, accumulation, and translocation of metals in five dominant mangrove species, as these systems are heavily impacted by anthropogenic interventions. The trace metal concentrations (mg kg-1) in the sediment of different mangrove habitats of Kerala ranged from 20 to 295 for Cu, 65 to 350 for Zn, 72 to 151 for Pb, 11 to 210 for Ni, 42 to 228 for Mn, 0 to 6 for Cd,124 to 565 for Cr, and 0 to 2.9 for Ag. An overall enrichment of metals was recorded in sediment, exceeding the prescribed effects range median (ERM) of consensus-based sediment quality guidelines (SQGs) for Cu and Cr concentrations at Munroe Island and Ni at Vypin, indicating a detrimental risk to biota in the sediments. Principal component analysis and a higher geoaccumulation index indicated the contribution of trace metals from industries, agricultural runoff, and urban waste disposal. The ecological risk index suggested that cadmium poses a very high risk to the mangrove ecosystem at Vypin. Furthermore, the bioconcentration factor for various trace metals in Avicennia marina and Lumnitzera racemosa in Ayiramthengu was > 2, suggesting that these species can accumulate trace metals, particularly Cr, Cd, and Pb. Further, our findings suggest that A. marina may be considered as an efficient metal trap for Cd in aerial parts, as indicated by the significant translocation factor (> 1) combined with the bioconcentration factor. Therefore, the study revealed that Munroe island and Vypin had a considerable level of contamination for toxic metals and Avicennia marina could be a promising candidate species for the phytoremediation of these trace metals in the coastal settings of Kerala state.

Mobile trace elements in sediments from lakes Hawassa, Koka, and Ziway in the Ethiopian Rift Valley.

The present work focuses on total concentrations of trace elements such as chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), and lead (Pb) and their operationally defined speciation in surface sediments from three Ethiopian Rift Valley Lakes (Hawassa, Koka, and Ziway). Total concentrations were determined using inductively coupled plasma-mass spectrometer (ICP-MS). A six-step sequential extraction was also applied to evaluate the mobilization potential of these elements. Compared with the consensus-based sediment quality guidelines (SQGs) developed for freshwater ecosystems, the total Zn concentration in sediments from Lakes Hawassa and Ziway, as well as Cr, Ni, and Zn in sediments from Lake Koka, was higher than the probable effect concentration (PEC), suggesting that these elements could have a negative effect on benthic organisms. The sequential extraction results showed that Cd, Mn, and Se were to a certain extent associated with the reversible fractions (F1-F3) in sediments, and thereby more mobile than the other investigated trace elements. Predictions of mobility of trace elements using the distribution coefficients (Kd) values were also in agreement with the sequential extraction results. Furthermore, multivariate statistical analyses showed that redox-sensitive fractions (F4 and F6) and the residual fraction (F7) were the dominant factors controlling most trace element mobility. Finally, applying the Risk Assessment Code (RAC) classification system, results showed that Mn in Lake Koka could pose a high risk, while Cd and Mn in Lake Hawassa as well as Cd, Mn, and Se in Lake Ziway sediments could pose medium risk to benthic organisms.

Research on the geochemical background values and evolution rules of lake sediments for heavy metals and nutrients in the Eastern China Plain from 1937 to 2017

For the first time, background quality guidelines have been developed for lake sediments along the Yangtze River. Evolution Rules of watershed environment in Eastern China were analyzed in 1937–2017. These methods of 137Cs and 210Pb radionuclide, 75% cumulative frequency, and background method were applied to calculate the sediment geochemical backgrounds (GB). The average GB values of Cu, Zn, Cd, Pb, Cr, total carbon (TC), total nitrogen (TN) and total phosphorus (TP) are 45.14 mg/kg, 86.99 mg/kg, 0.29 mg/kg, 33.71 mg/kg, 110.90 mg/kg, 17.20 mg/g, 1.60 mg/g, and 665.78 mg/kg, respectively. The radionuclide methods indicated that the sediment rate of 34 cm corresponding to 1963 is 0.63 cm yr−1. The risk and accumulation of the sediment metals and nutrients in Yangtze Plain were uncontaminated levels before 1960, raised since 1980, and increased significantly in 2000. The Cd, TC, and TN in lake sediment were at low to moderate pollution, and few lakes are at high pollution. Sediment background values of the plain are different from soil background values in China and Consensus-Based Sediment Quality Guidelines in Europe/America. Results of sediment quality guidelines provide an important guidance for pollution prevention, environmental management, and risk assessment, especially the formulation of environmental laws.

Heavy Metals Content in Water and Sediments in the Upper Litani River Basin, Lebanon

Surface water quality is largely influenced by both natural processes and anthropogenic inputs. This study involves the characterization of the concentration of heavy metals of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn, and the sources of pollution in water and sediment of the Upper Litani River Basin (ULRB) in Lebanon. The investigation was performed during three seasons of rainy, mid-rainy spring and wet periods for two years during different flow rates. Sediments were characterized by a set of chemical analyses, cation exchange capacity (CEC), mineralogy of the sediments, X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FTIR). To assess metal contamination in sediment, Consensus-Based Sediment Quality Guidelines of Wisconsin (CBSQG) were applied. The metals contamination in the sediments was also evaluated by contamination factor (Cf). The test results showed that the effect of seasonal variations was significant in the Upper Litani River Basin. Principal Compound Analysis (PCA) and Pearson’s correlation were also performed in this study to compare and determine the correlation between metals in water and sediments. The concentrations of Pb, Cd, Cu, Cr and Zn in all sediment samples are above the norms in winter, while Fe was increased in summer. The results showed that the importance of monitoring of changes of heavy metals values and physico-chemical characterization of different parameters could represent the possibility of a comprehensive assessment of negative pressures on the water and soil ecosystem of Litani River Basin during different seasons.

Understanding potentially toxic metal (PTM) induced biotic response in two riparian mangrove species Sonneratia caseolaris and Avicennia officinalis along river Hooghly, India: Implications for sustainable sediment quality management

Elevated human-induced activities have prompted significant uncontrolled release of potentially toxic metals (PTM) to the undisturbed ecosystem throughout the globe. Riparian mangrove vegetations act as a natural purifier of wastewaters and assist in maintaining a healthy ecosystem. We have investigated the elevated PTM-induced stress and biotic response of two riparian mangrove species e.g. Sonneratia caseolaris and Avicennia officinalis by river Hooghly. The increased PTM concentrations were observed throughout the river bank; with the maximum pollution load at Chemaguri (S9). Except Co, Cr and Pb, higher enrichment factor (1.97–8.89) and contamination factor (0.64–2.88) values were observed for Cd, Cu, Fe, Zn. Mn, and Ni. Geo-accumulation index (−2.2 – 0.92) values indicates natural geogenic accumulation of Cu in the riparian mangrove sediment. Thus, sediment quality indices suggest except Cu, enrichment of all studied PTMs was sourced from anthropogenic activities. The sediment of the region when compared with consensus-based sediment quality guidelines shows considerable ecotoxicological risks and threat towards human health considering Ni accumulation. The highest potential ecological risk index value was observed in Chemaguri (S9). The biotic response of riparian mangroves was characterized by reduced photosyhthetic pigments (Chlorophyll a and Chlorophyll b) and increased activity of antioxidative stress enzymes (POD, CAT and SOD). Significant statistical relationship between antioxidative enzyme activity, photosynthetic pigments and bioaccumulated PTMs reflects active functioning of detoxification mechanism in the riparian mangrove species.

Spatial-temporal dynamics, ecological risk assessment, source identification and interactions with internal nutrients release of heavy metals in surface sediments from a large Chinese shallow lake

The surface sediment concentrations of heavy metals (Cu, Zn, Pb, Cd, Cr, Hg, and As), major metals (Fe and Mn), and the nutrient concentrations in the interstitial water of Lake Houguan, a large eutrophic shallow lake, were surveyed for three years. The results showed that Cu, Zn, and Fe were significantly higher in the east lake parts, and Cd in November was significantly higher than April. 19% of Hg and all of As were larger than the probable effect concentrations (PECs) according to the consensus-based sediment quality guidelines (SQGs), and the geo-accumulation index (Igeo) indicated As, Hg, and Cd were slightly polluted to severely polluted. The RI value (average 704.2) of the potential ecological risk index (PERI) suggested that heavy metals posed very high ecological risks with most of the contributions induced by Cd and Hg. The consequence of hierarchical clustering analysis (HCA) and principle component analysis (PCA) identified Cd, As, and Pb might originate from urbanization, industrial pollution, and agricultural activity; Hg might be from atmospheric deposition and anthropogenic sources above; Cu, Zn, Cr, Fe, and Mn might be from both natural and anthropogenic sources. The Spearman correlation analysis indicated Pb and As were significantly positively correlated with total nitrogen, while Cd significantly negatively correlated with sulfate; As was significantly correlated with ammonia, sulfate, and nitrate in the interstitial water. These results suggested eutrophication might affect sedimental heavy metals by increasing organic matter or influencing the redox potentials in the sediment.

Distribution of polycyclic aromatic hydrocarbons (PAHs) in the bottom sediments of a dam reservoir, their interaction with organic matter and risk to benthic fauna

PurposeThe aims of the study were to investigate the interaction between fractions of organic matter and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments and to use mussels as passive biomonitors and consensus-based sediment quality guidelines for ecological risk assessment in sediments.MethodsBottom sediment samples were taken from 46 points located in the Rożnów reservoir (Poland). The sediment organic matter (SOM) characteristics included total carbon (TC), total organic carbon (TOC), humic acid carbon (Cha), fulvic acid carbon (Cfa), non-hydrolysing carbon (Cnh), and dissolved organic carbon (DOC). The extraction procedure was carried out in bottom sediments as well as in freeze-dried mussel tissue samples to directly determine the accumulation potential of PAHs to the living organisms in their natural environment.ResultsThe content of organic matter fractions was in the following order: Cfa (fulvic acid) > Cnh (non-hydrolysing carbon) > Cha (humic acid) > DOC (dissolved organic carbon). The mean ∑16PAHs (μg kg−1) concentration was 1755.2 ± 724 (total) and 256 ± 254 (bioavailable) in sediments and 1740 ± 72.2 in the mussel tissues. A significant positive correlation was found between the concentration of PAHs in the mussel tissues and the total and bioavailable concentration of PAHs in bottom sediments.ConclusionThe PAH concentration in bottom sediments depended on the stabile carbon forms Cnh. Principal component analysis (PCA) suggests that the fine fraction can significantly increase the bioavailability of PAHs and can be an important factor in the distribution of PAHs in the sediments.

The role of local geochemical and mineralogical backgrounds as essential information to build efficient sediment quality guidelines at high-mountainous hydrothermally-altered basins (Mapocho basin, Chile)

The Mapocho River's upper basin (Chilean Central Andes) was studied as a proxy of a high-mountainous hydrothermally-altered (HMHA) system comprised by three sub-basins developed over very different rocks and submitted to different anthropic pressure: 1) a natural acid rock drainage (i.e., Yerba Loca), 2) a creek with mining activity in its headwaters and hydrochemically classified as non-affected by acid mine drainage (i.e., San Francisco), and 3) a low metal concentration creek (i.e., Molina). In general terms, the geochemical composition of the clastic sediments was consistent with the geochemistry inferred from the mineralogical study. However, sediments with a smaller grain size showed higher concentrations than the bigger grain size counterparts for elements such as Fe, S, Cu and As. This behavior was particularly evident in the Yerba Loca basin and it was attributed to the seasonal appearance of Fe- and Al-rich precipitates as constituents of the finer sediments. Different methodologies for the calculation of geochemical backgrounds (Tukey's inner fence, TIF; Median + 2*Median Absolute Deviation, MAD; and 95th percentile) were tested. Results suggest that the 95th percentile-method was the most appropriate for this type of mountainous systems. Using the selected methodology, three different geochemical backgrounds were calculated: 1) Yerba Loca basin, 2) Molina basin, and 3) Mapocho Upper basin. When the generated background levels were compared with the Consensus-Based (CB) Sediment Quality Guidelines; Fe, Mn, Zn, Pb, Cu, Cr, Ni and As showed background values that were consistently higher than the values set by the CB Threshold Effect Concentration and, even higher than the CB Probable Effect Concentration for Fe (MUBBackground: 6.78 wt% vs CB PEC: 4.00 wt%; and Cu (MUBBacground: 3387 mg kg−1 vs CB PEC: 149 mg kg−1). The present study clearly states the paramount importance of having a solid geochemical background before any attempt of a sediment risk assessment is made at HMHA regions.

Assessment of persistent organic pollutants in soil and sediments from an urbanized flood plain area.

Polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phenolic compounds (PCs) are persistent organic compounds. Contamination of these potentially toxic organic pollutants in soils and sediments is most studied environmental compartments. In recent past, studies were carried out on PAHs, OCPs and PCs in various soils and sediments in India. But, this is the first study on these pollutants in soils and sediments from an urbanized river flood plain area in Delhi, India. During 2018, a total of fifty-four samples including twenty-seven each of soil and sediment were collected and analyzed for thirteen priority PAHs, four OCPs and six PCs. The detected concentration of ∑PAHs, ∑OCPs and ∑PCs in soils ranged between 473 and 1132, 13 and 41, and 639 and 2112µg/kg, respectively, while their concentrations in sediments ranged between 1685 and 4010, 4.2 and 47, and 553 and 20,983µg/kg, respectively. PAHs with 4-aromatic rings were the dominant compounds, accounting for 51 and 76% of total PAHs in soils and sediments, respectively. The contribution of seven carcinogen PAHs (7CPAHs) in soils and sediments accounted for 43% and 61%, respectively, to ∑PAHs. Among OCPs, p, p'-DDT was the dominant compound in soils, while α-HCH was found to be dominated in sediments. The concentrations of ∑CPs (chlorophenols) were dominated over ∑NPs (nitrophenols) in both the matrices. Various diagnostic tools were applied for the identification of their possible sources in soil and sediments. The observed concentrations of PAHs, OCPs and PCs were more or less comparable with the recently reports from various locations around the world including India. Soil quality guidelines and consensus-based sediment quality guidelines were applied for the assessment of ecotoxicological health effect.

Heavy Metal Contamination Levels in Clams (Galatea paradoxa, Born 1778) and Surface Sediments from Mono River Estuary, Togo, and its Health Implications

Heavy metal pollution in aquatic ecosystems is one of the most important threats of human health and food chain. Thus, in this study, the level of Cd, Fe, Hg, Mn, Pb and Zn accumulation in surface sediments and in Galatea paradoxa , were investigated to estimate their potential health risks via consumption to residents alongside the Mono river, Togo-Benin border. Samples were collected at two fishing areas and analyzed using flame atomic absorption spectrophotometry Moreover, the likely health risks developed as a result of human contamination by heavy metal through clam consumption was also assessed using target hazard quotient (THQ) and hazard index (HI). The mean maximal metal concentrations (μg/g dw) were as follows: Fe (25624) > Mn (1176.0) > Zn (23.29) > Pb (4.67) > Hg (0.038) in silty sediments and Fe (15692) > Mn (654.78) > Zn (12.53) > Pb (2.42) > Hg (0.034) in sandy sediments. Cd content were all below the detectable limit. When compared against some consensus-based sediment quality guidelines (TEL, ERL, AFNOR), it was observed that all the concentrations, excluding Fe levels in the samples, were lower than reference values. Similarly, computed PLI was less than 1 indicating that the lower tidal parts of the Mono were unpolluted. The accumulation pattern of studied trace metals in the clams followed a slightly different trend from that found in the sediments (Fe>Zn>Mn>Hg>Pb>Cd). Fe (1353 ± 162 μg/g dw) and Zn (51,8 ± 8.9 μg/g dw) content in whole tissues of G. paradoxa were well above the maximum concentration allowable by food safety criteria. In contrast, Cd (0.097 mg/kg dw), Hg (0.24 mg/kg dw) and Pb (0.18 mg/kg dw) content were very low. Computed THQ values were all below 1, with highest results found in the small size clams regardless of the heavy metals. The HI values indicate that none of the analyzed heavy metals may pose serious risk to consumers through the clams studied. The highest risk was posed by small clams, followed in decreasing order by medium and large clams. We therefore suggest that the clams taken from main fishing locations at Mono river are safe to eat. Keywords: Heavy metals, Sediment pollution, Galatea paradoxa , Human health, Mono River DOI: 10.7176/JBAH/11-4-06 Publication date: February 28 th 2021

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.

Metal contamination assessment in water column and surface sediments of a warm monomictic man-made lake: Sabalan Dam Reservoir, Iran

Abstract In this study, metal concentrations in the water column and surface sediment of the Sabalan Dam Reservoir (SDR) were determined. Moreover, heavy metal pollution index (HPI), contamination index (CI), heavy metal evaluation index (HEI), enrichment factor (EF), geo-accumulation index (Igeo), sediment quality guidelines (SQGs), consensus-based SQGs (C-BSQGs), and mean probable effect concentration quotients (mPECQs) were evaluated for water and sediments of SDR. It was observed that metal concentrations in river entry sediment were lower, but those in river entry water were higher than corresponding values in the vicinity of the dam structure. The HPI values of water samples taken from 10 m depth in the center of SDR exceeded the critical limit, due to high concentrations of arsenic. However, according to CI, the reservoir water was not contaminated. The HEI values indicated contamination of SDR water with metals at 10 m depth. A comparison of water quality indices revealed that HEI was the most reliable index in water quality assessment, while CI and HPI were not sufficiently accurate. For SQGs, As and Cu concentrations in sediments were high, but mPECQ, Igeo, and EF revealed some degree of sediment pollution in SDR. The calculated EF values suggested minor anthropogenic enrichment of sediment with Fe, Co, V, and Ni; moderate anthropogenic enrichment with As and Mn; and moderate to severe anthropogenic enrichment with Cu. A comparison of SQG values revealed that the threshold effect and probable effect levels were the most reliable metrics in the assessment of sediment toxicity. Statistical analysis indicated similarities between metal concentrations in the center of the reservoir and near to the dam structure, as a result of similar sediment deposition behavior at these points, while higher flow velocity at the river entry point limited deposition of fine particles and associated metals.

Mineralogical and geochemical characterisation of alkaline lake sediments to trace origin, depositional processes, and anthropogenic impacts: Inle Lake (Southern Shan State, Myanmar)

Southeast Asia contains a major portion of wetland areas of international significance, but only 14% of these wetlands are under protection. Inle Lake is the second largest freshwater body in Myanmar and the most important for its environmental, economic, and agricultural values. However, the lake is seriously threatened by anthropic activities as they are dramatically decreasing its open water surface. While water-quality studies have assessed the presence of nutrients and contaminants, little is known about the sediment quality. Therefore, the overall objective of the present study was to analyse the natural sedimentation patterns and the anthropogenic disturbances in this lake. To this end, both grab and core sediments were investigated by combining mineralogical, morphological, and geochemical analyses, and their composition was compared to the composition of rocks and soil from the watershed. Mineralogical data indicate that sediment samples collected at or near the main inflow, and at the outflow show a lower abundance (about 43%) of calcite, which generally increases with depth in sediment cores, reaching more than 90% in the centre of the lake. Lower calcite contents correspond to higher percentages of other minerals. These findings allow us to clearly distinguish the allogenic (quartz, mica/illite, kaolinite, and detrital calcite) from the endogenic (mostly calcite) minerals, as confirmed by the soil and rock mineralogy. The origin of the mineral contents at the different sites is further supported by the observation of the grain morphology and composition. The most abundant metal in the lake sediments is Ca, in agreement with the high calcite content. Following in order of abundance are Al, Fe, and K, which are connected to the detrital input to the lake. In the rock and soil samples, the most abundant trace element is Mn, which is significantly correlated with many other trace elements (e.g., Co, Cr, Cu, Ni, V, Zn, and As), suggesting their common lithogenic origin. Similarly, in the lake sediments, the trace elements Co, Cr, Cu, Ni, Pb, V, Zn, and As display fairly homogenous concentration ranges, in the order of tens of ppm, and are strongly correlated with the detrital minerals (mica, kaolinite, and quartz) and negatively correlated with the calcite content. The mineralogical and elemental distribution in the lakebed area and with depth in the sediment cores allowed us to identify the increased soil and bedrock erosion as a major anthropogenic impact to the lake. The sedimentation disturbance is especially evident at the main inflow, the Nanlit stream, which has caused the development of a large alluvial fan, visible in satellite images. This large sediment input is likely to have accelerated the decrease in open water surface and in depth of this shallow lake. Additionally, when the measured concentrations of Potentially Toxic Elements were compared to consensus-based Sediment Quality Guidelines (SQGs), it was shown that As, Cr, Cu, Ni, Pb, and Zn often exceeded the threshold effect concentration (TEC), and that Cr, Ni, and Pb sometimes exceeded the probable effect concentration (PEC). On the other hand, Enrichment Factors (EFs), calculated with respect to soils of the watershed, showed minimal enrichment and indicated that the potential toxicity effect was primarily a result of detrital sedimentation outpacing carbonate sedimentation. Sediment characterisation allowed us to obtain a better understanding of lake dynamics and environmental impacts, which is fundamental in achieving effective management and maintenance of the ecological character of Inle Lake, in line with the objective set by the Ramsar Convention for wetlands of international relevance.

Spatial variation of organochlorine pesticides and dissolved organic matter in urban closed lakes

Closed lakes located in urban parks act as sinks of organochlorine pesticides (OCPs), which have been used, for decades, as insecticides, herbicides and fungicides. The closed lakes from Bucharest, Romania, are periodically managed to prevent eutrophication and accumulation of pollutants. However, it is not known if these practices reduce or enhance the legacy pollution with OCPs. The aim of this study was to explore the spatial variation of OCPs in closed lakes. The total concentration of OCPs in water and sediments ranged between 0.0176 and 37.1 µg/L, and between 122 to 1,890 ng/g, respectively. The concentrations of OCPs were compared with the consensus-based sediment quality guidelines (SQGs) in order to evaluate the ecological risks of sediments. The highest potential adverse effects were associated with γ-HCH exposure. Periodical draining and dredging of lakes lead to the resuspension of contaminants, increasing pesticide bioavailability and accumulation in sediments. In addition, we observed that fluorescent dissolved organic matter (DOM) might influence the OCPs cycle. The quantity and character of fluorescent DOM can provide further insight into OCPs degradation. Also, this study may help urban planners to determine the state of urban waters and to find the best solution for water management.

An evaluation of potential toxic metals in sediments of a tropical watershed in southern Benue Trough, Nigeria

This study assessed heavy metal contamination in sediments within the Anambra drainage basin in Southern Benue Trough, Nigeria. Twelve river sediments were collected from the basin upstream and downstream in two seasons—rainy and dry seasons. The control was collected from the basin source. Samples were analyzed using X-ray fluorescence (XRF) spectroscopy for common major Potential Toxic Metals (PTMs). Concentration of zinc (Zn), nickel (Ni), manganese (Mn), iron (Fe), chromium (Cr), lead (Pb), vanadium (V), molybdenum (Mo), scandium (Sc) and europium (Eu) were detected in trend: Fe > Mn > Zn > Pb >>> Cr > Ni > Mo > Eu > Sc. Contamination trend in rivers shows Adada > Oji > Ezu > Obele > Mamu > Ankpa. The rainy season and the upstream sediments had lower concentrations than the dry season and downstream, respectively. Sediments had higher PTMs concentrations than the background sediments, though most PTMs concentrations were within the recommended standards- USEPA, WHO and Consensus-Based Sediment Quality Guidelines (CBSQGs). Contamination factor (Cf), enrichment factor (Ef), and geo-accumulation index (Igeo) recorded range from 0 to 15, 0 to 6.69 and − 8.43 to 3.32 respectively, signifying significant accumulation and enrichment of PTMs. Pollution load index (PLI) of the heavy metals ranges between 0.24 and 1.34, which suggest that at the different seasons, the basin was enriched with PTMs to a pollution level through anthropogenic activities. In the Anambra drainage basin, concentration and distribution of heavy metals may have been influenced by both non-anthropogenic and anthropogenic processes such as geology of the area, weathering and erosion as well as mining and agricultural activities.

Distribution, assessment and coupling relationship of heavy metals and macroinvertebrates in sediments of the Weihe River Basin

In order to evaluate the distribution of heavy metals and macroinvertebrates and to clarify the coupling relationship between them, a total of 54 samples of the 0–10 cm layer and 10–20 cm layer sediments were collected from 27 sites in the Weihe River Basin. Geo-accumulation index, Ecological potential risk index, Pollution load index, and Consensus-based sediment quality guidelines were employed to evaluate the ecological risk associated with heavy metals in sediments. Macroinvertebrate community structure was analyzed, following which the quality surrounding habitat was evaluated basing on the indexes. Our results confirmed that the orders of pollution level were 10–20 cm >0–10 cm at different layers and Cd > Ni > Pb > Cu > Cr > Zn for different metals. Through correlation analysis and redundancy analysis, macroinvertebrate metrics exhibited significant correlations with heavy metals. Gastropods and R (Ratio of Ephemeroptera and Trichoptera index to Chironomidae) were selected as bioindicators in overall qualitative analysis. In the 0–10 cm layer, Gastropods and Family biotic index could be selected as bioindicators. Whereas, in the 10–20 cm layer, suitable bioindicators were Oligochaetes and DM (Maralef richness index). Heavy metals, especially Cd, in sediments may pose adverse impact on macroinvertebrate community.