Probable Effect Concentration Research Articles

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.

Assessment of Polycyclic Aromatic Hydrocarbons Pollution in Lake and Reservoir Sediments in Korea

Polycyclic aromatic hydrocarbons (PAHs) are pollutants that require management as they are continuously formed by natural and anthropogenic processes. We assessed PAH pollution in freshwater sediment in major lakes and reservoirs of Korea. We collected samples of surface sediment in spring 2018; these were sieved to obtain sand, silt and clay (<2 mm). We extracted dry sediment using Hexane:Acetone(1:1) and analyzed the concentration of 16 PAHs by GC-MS. Measured concentration of PAHs was compared with threshold effect concentration(TEC) and probable effect concentration (PEC), and concentration ratio of chemical species was analyzed to track source. PAH concentrations ranged from 13 ng/g-dw to 1 337 ng/g-dw, (median 123 ± 204 ng/g-dw),which are below TEC and are similar or slightly lower than those reported by previous studies. At most sites, the dominant PAH source was natural combustion such as forest fires rather than anthropogenic such as petroleum. In contrast, the site with the highest PAH concentration (1 337 ng/g-dw) in Dae-am reservoir indicated natural and anthropogenic sources. Pollution levels of PAHs in reservoirs and lakes in Korea is not of concern in general. However, some sites with PAHs from anthropogenic sources need to be monitored to investigate possible increase in PAH concentrations in future. Key Words: PAHs, Sediment, Pollution assessment, Pollution evaluation guideline, Composition ratio of 16 PAHs

Potential availability of trace metals in sediments in southeastern and southern Brazilian shipyard areas using the DGT technique and chemical extraction methods

Speciation and partitioning of trace metals, from solid to solution phases of sediments, control their bioavailability and thus their potential ecological risk to organisms. Therefore, in order to obtain a broad evaluation of their risk, it is necessary to couple methodologies that are able to assess metal mobility in sediment. In this study, the Diffusive Gradients in Thin Films (DGT) technique and the application of 0.1 M HCl acid extraction methods, together with solid-state voltammetric sensors, were used with the objective of assessing mobility and potential availability of Cr, Cu, Ni, Pb, V and Zn in sediment porewaters and solid sediments in southeastern and southern Brazilian shipyard areas. The highest labile metal concentrations were found in shipyards with the longest histories of operations. Trace metal distributions in porewater and in the solid phase of sediments (labile metals) and significant correlations among metals enabled to distinguish the contribution of anti-fouling paint components. The diffusive flux of every metal measured at the surface of the sediment indicated that CuDGT had the highest flux (3.66E−03 mmol·m−2 d−1) in the shipyard with the longest operating time. Therefore, enrichment was observed for Cu, Pb and Zn in sediments, indicating a possible ecological risk level of ‘Effects Range Median’ to ‘Apparent Effects Threshold’ for oyster larvae (Mollusca) (Cu), bivalves (Pb) and the infaunal community (Zn). Probable Effect Concentrations (PEC) to sediment-dwelling biota can be expected as well, related to high concentrations of Cu and Zn in sediment. This study allowed a comprehensive evaluation of potential bioavailability and ecological risk of trace metals in aquatic systems where there is continuous and specific input of these elements. The use of the DGT technique with solid-state voltammetry in the sediment of distinct Brazilian estuarine systems demonstrated its potential to be applied in future environmental network programs.

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.

Trace elements in sediments and fish from Atrato River: an ecosystem with legal rights impacted by gold mining at the Colombian Pacific

The Atrato watershed is a rainforest that supports exceptional wildlife species and is considered one of the most biodiversity-rich areas on the planet, currently threatened by massive gold mining. Aimed to protect this natural resource, the Constitutional Court of Colombia declared the river subject to rights. The objective of this study was to quantify trace elements in sediments and fish from Atrato watershed, assessing their environmental and human health risk. Forty-two trace elements were quantified using ICP-MS. Thirty-one elements increased their concentration downstream the river. Concentration Factors (CF) suggest sediments were moderately polluted by Cr, Cu, Cd, and strongly polluted by As. Most stations had Cr (98%) and Ni (78%) concentrations greater than the Probable Effect Concentration (PEC) criteria. Together, toxic elements generate a Pollution Load Index (PLI) and a Potential Ecological Risk Index (RI) that categorized 54% of the sediments as polluted, and 90% as moderate polluted, respectively. Hemiancistrus wilsoni, a low trophic guild fish species, had the greater average levels for Ni, Cu, As and Cd, among other elements. Rubidium and Cs showed a positive correlation with fish trophic level, suggesting these two metals biomagnify in the food chain. The Hazard Quotient (HQ) for As was greater than 1 for several species, indicating a potential risk to human health. Collectively, data suggest gold mining carried out in this biodiversity hotspot releases toxic elements that have abrogated sediment quality in Atrato River, and their incorporation in the trophic chain constitutes a large threat on environmental and human health due to fish consumption. Urgent legal and civil actions should be implemented to halt massive mining-driven deforestation to enforce Atrato River rights.

Chemical Monitoring of Organic Ecotoxicants in Aqueous Systems

Monitoring of organochlorine pesticides (OCP), polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) in surface waters, sediments and aquatic lives of the benthic layer from different water systems of Ukraine was carried out. Information about the levels of these organic contaminants was collected, summarized and presented according to universally accepted regulatory standards that determine the toxicity of compounds of these classes. Regularities of variations of ecotoxicants concentrations in five water systems of the Dnipro river and the Black Sea (Dnipro-Bug estuary, the Danube delta, Balaklava bay, Sevastopol bay) were established. It was found that in many bottom sediment samples the recorded levels of OCP, PCB, and PAH exceed the values of TEC (Threshold Effect Concentration) and PEC (Probable Effect Concentration). To assess the toxicity of hydrobionts, the content of OCP and PCB is given as relative to the toxicity equivalent factor (TEF) and toxicity equivalent (TEQ). The levels of PCB in hydrobionts are presented relative to TEQ and indicate that hydrobionts of the bottom layer are significantly contaminated with compounds of OCP and PCB and thus bioconcentration of such organic contaminants by high organisms along the trophic chain is possible.

Concentration and Distribution of Organochlorine Pesticides in Sediments of the Niger River, Nigeria.

Pollution in aquatic ecosystems is a serious environmental concern. There is a great need for constant assessment and monitoring of hazardous substances, particularly in aquatic environments in developing countries, as rivers are media with easy trans-boundary transport of chemical substances. The present study assessed the occurrence and distribution of organochlorine pesticides (OCPs) in the sediments of the Niger River, Nigeria. A total of 120 samples of sediment were collected from 15 locations along the river using Van Veen grab. The Environmental Protection Agency (USEPA) 3570 method with slight modification was used for sample preparation. Organochlorine pesticides were analyzed using Hewlett Packard 5890 series II gas chromatography with electron capture detector. Confirmation of OCPs was performed using a gas chromatograph/mass spectrometer (Shimadzu QP2010) and capillary column type HP1MS (30 m × 0.25 um × 0.25 mm id). The highest concentration of ∑OCPs in the sediment samples of the River Niger (5023±1596 μg/kg, 4672-7009 μg/kg) was detected in a location at Onitsha, while the lowest concentration (1570±204.5, 1214-1820 μg/kg) was detected in a location at the Nicolas River. High values of ∑OCPs (>2000 μg/kg) were detected in all of the locations except in three locations where lower levels were detected. The ∑OCPs were higher during the dry season compared to the rainy season. This may be because the resident time of the sediment transported was higher during the dry season compared to the rainy season, which is characterized by storms, high current, and bottom scour. The chlordane concentration ranged between 24.4 and 134.1 μg/kg dry weight (dw) in locations Nicolas 14 and Lokoja 5; and the Probable Effect Concentration guidelines were exceeded. Dieldrin was detected at very low levels in most of the locations and ranged from 5.67 to 70.3 μg/kg dw in locations Onitsha 9 and 8; and the Probable Effect Concentration guideline was only exceeded in location Onitsha 8; however, the Toxic Effect Concentration guideline was exceeded at all of the locations. Dichlorodiphenyldichloroethane (DDD) was not detected in location Lokoja 6 or 7, and Onitsha 8 and 9, although the concentration in all other locations exceeded the guidelines. Dichlorodiphenyldichloroethylene (DDE) concentrations exceeded the guidelines except in location Nicolas 13. Due to the environmental/human risk and potential danger of the elevated levels of OCPs, there is a need for continuous monitoring of the Niger River. The authors declare no competing financial interests.

Ecological risk assessment of metals and metalloid in bottom sediments of water reservoir located in the key anthropogenic \u201chot spot\u201d area (Poland)

Study was aimed to assess the potential ecological risk of nine metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) and one metalloid (As) in bottom sediments of the Dzierżno Duże Reservoir located in the key anthropogenic “hot spot” area—Upper Silesian Industrial Region (Poland). Sediments were collected in seven sampling sites, along the main axis of a reservoir. Statistical analysis revealed a significant correlation (p < 0.05) between the potentially toxic elements, which indicated that they plausibly originate from the same source of contamination or have a similar accumulation behavior. Several indices were used to assess ecological risk associated with examined elements, i.e., Enrichment Factor, Geoaccumulation Index, Contamination Factor, Potential Ecological Risk Factor, Probable Effect Concentration, Threshold Effect Concentration, Degree of Contamination and Risk Index. The values of analyzed indices indicate that sediments are highly to extremely highly contaminated, especially by Cd, Pb, Zn, and As, which simultaneously pose the highest ecological risk. The results of Cluster Analysis (CA) and Principal Component Analysis (PCA) indicate that Cd, Cr, Fe, Ni, Pb, Zn, and As in the bottom sediments are most likely of anthropogenic origin, while Mn rather from natural sources. The obtained results confirm the usefulness of different indices in assessing the ecological condition of water bodies and prove that the problem of toxic elements contamination in bottom sediments of the Dzierżno Duże Reservoir poses a serious environmental threat.

Seasonal and spatial contamination statuses and ecological risk of sediment cores highly contaminated by heavy metals and metalloids in the Xiangjiang River.

To reveal seasonal and spatial variations of heavy metals and metalloids (HMMs) in sediment of the Xiangjiang River, a total of 24 water and 649 sediment samples were collected from six sampling stations in the Songbai section of the river which had been polluted by HMMs for 100years. Their contamination statuses and ecological risk were determined by enrichment factor (EF), geo-accumulation index (Igeo), pollution load index (PLI), and mean probable effect concentration quotients (mPECQs) analyses. The results revealed a unique seasonal distribution of metals in the sampling stations: The highest concentrations were revealed in the dry seasons (autumn and winter) and the lowest during the wet seasons (spring and summer). It exhibited a greater seasonal variation in the estuary sediment cores (sites ME and MW) than in the cores of other sites. Moreover, the highest concentrations of the tested metals were also found in the estuary sediment cores in the dry seasons (autumn and winter). The highest vertical concentrations of Pb, Zn, Cu, Ni, As, Fe, and Mn were observed at the depths of 16-36cm in all of the sampled sediment cores. The EF, Igeo, PLI, and mPECQs values of all samples in autumn were higher than in summer. Cd posed the highest ecological risk in all seasons, although its concentrations were lower compared to other studied elements. Our results will benefit to develop feasible sediment quality guidelines for government monitor and remediate the local sediments in the Xiangjiang River.

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.

Heavy Metal Signature and Environmental Assessment of Nearshore Sediments: Port of Koper (Northern Adriatic Sea)

Heavy metal abundance and potential environmental risks are reported for surface sediments (n = 21) from the Port of Koper area, Republic of Slovenia. The enrichment factor (EF) indicates minor enrichment in arsenic (As), cadmium (Cd), copper (Cu), molybdenum (Mo), lead (Pb), antimony (Sb), and zinc (Zn), moderately to severely enriched with nickel (Ni). The trace metal chemistries, in the context of sediment quality guidelines (SQG), imply adverse threshold effect concentrations (TEC) and probable effect concentrations (PEC), for Ni only. Sediment sequential leaching experiments demonstrated that the majority of heavy metals were of natural lithogenic origin and low bioavailability. The heavy metals’ potential for “Risk Assessment Code” values exhibited no or low anthropogenic environmental burden, with the exception of Mo.

Potentially toxic elements in water, sediments and fish of the Evrotas River under variable water discharges

Among different stressors like drought, hydro-morphological alterations, and pollution from agricultural activities, nutrients, organic compounds and discharges from wastewater treatment plants (WWTPs), potentially toxic elements (PTE) may also contribute to the overall pollution of the Evrotas River, Greece. Nevertheless, information on pollution of elements in water and sediments in this river is scarcely documented. There is also no information available on the impact of elemental pollution from the aquatic environmental compartments on biota. To fill these gaps, in this study, water, sediment and fish samples were collected from four sampling sites along the Evrotas River under variable flow regimes (July 2015, higher discharge; June 2016, low discharge and September 2016, minimum discharge). Total and dissolved element concentrations in water samples, total and acetic acid extractable contents in sediments, and element concentrations in fish samples were determined by inductively coupled plasma mass spectrometry and significant relationships between samples were established using correlation analysis. The concentrations of PTE (Ni, Cr, Cd, As, Pb, Zn and Cu) in water were generally low, while elevated Ni and Cr contents were found in sediments (up to 150 and 300 mg/kg, respectively), with total Cr concentration in water and sediment being positively correlated. The ecological risk posed by the simultaneous presence of PTE in sediments evaluated by calculating the Probable Effect Concentration Coefficient (PEC-Q), demonstrated that PEC-Qs, which were above the critical value of 0.34, derived mostly from Cr and Ni inputs. Since their mobile sediment fraction was extremely low, Cr and Ni origin is most probably geogenic. The analysis of elements in the target fish species, the Evrotas chub, showed low to moderate PTE concentrations, with Pb being positively correlated with total Pb concentration in water. Moderate Zn concentrations found in fish samples from the Evrotas are possibly derived from pesticides and fertilizers.

Heavy metal assessment in stream sediments from the rivers passing through the mining area

Stream sediment samples in two sizes of sand and clay/silt from the Chodarchay and Gilankesheh rivers which pass through the Chodarchay copper deposit, northwestern Iran, were measured for their metal concentrations using a sequential extraction procedure. The average concentrations of cadmium (18.22) in sediments from the rivers exceed the world average shale and continental upper crust values. Based on Geo-accumulation Index, cadmium is intensely elevated (in the clay fraction greater than 5 and in the sand fraction between 3 and 5), arsenic and lead are slightly elevated in a few stations and others are not-elevated. The zinc and copper values are almost equal to or lower than Geo-accumulation Index; thus, the sediments are unpolluted with respect to zinc and copper. Enrichment factor values confirm the risk of cadmium in the environment. Comparison of the mean heavy metal concentrations in the sediments with threshold effect concentration and probable effect concentration values shows that cadmium (clay/sand = 15.23/7.77) is higher than the threshold effect concentration and probable effect concentration values, while copper (13.41/7.71), lead (6.38/9.18), zinc (18.26/8.19), and arsenic (3.60/1.14) are lower than the threshold effect concentration values. The cadmium and lead could cause serious danger for river biota. Based on pollution intensity, sediment samples from both rivers are divided into low to highly enriched in lead, zinc, and copper, very high to intensely enriched in arsenic, and intensely enriched in cadmium and arsenic. The majority of metals are observed in the clay/silt fraction.

Heavy metal pollution and spatial distribution in surface sediments of Mustafakemalpaşa stream located in the world's largest borate basin (Turkey)

Mining activities in addition to the geology of Mustafakemalpaşa catchment have for long been linked to its deteriorating water and sediment quality. This study assessed contamination levels of heavy metals and other major elements (Pb, As, B, Cd, Zn, Cr, Mo, Co, Ni, Cu, and Ag) in surface sediments of the area, and identified possible pollution sources. Sediment quality indicators, such as contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo) and sediment quality guidelines were used, in addition to multivariate statistical technics; Pearson Correlation Matrix (PCM), Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). The highest contamination (annual average > 110 mg kg-1) was revealed by B, Cr, Ni, Zn and As. Moreover, As, Cd and Ni levels exceeded their respective probable effect concentrations (PEC), posing a potential negative impact to biota. The highest Igeo values were recorded for Cr, B, Ni, As and Zn, and occurred near urban settlements and mining sites, particularly of coal and chromium. The present study also suggests use of site rank index (SRI) as an alternative to pollution load index (PLI), since the former is derived from the data of interest and eliminates arbitrary classifications. The sources of heavy metals in the sediments were attributed to fly ashes of coal-powered plants, urban waste leachate and weathering of sulfide ore minerals for Pb, Zn and Cu; urban-industrial wastes and mining wastes for Ni. Although Cr, As, Cd and B were ascribed to natural occurrence, their presences in river sediment is accelerated by mining.

Assessment of heavy metal pollution, distribution and source apportionment in the sediment from Feni River estuary, Bangladesh

Heavy metal pollution in sediment resources may pose serious threat to ecosystem and human health through food web. In this study, surface sediment samples of 10 stations along the Feni River estuary were analyzed to profile the accumulation, sources and pollution levels of heavy metals. The results revealed that the average contents (μg g−1) of eight selected heavy metals followed the order of Mn (37.85) > Cr (35.28) > Ni (33.27) > Co (31.02) > Pb (6.47) > Ag (1.09) > As (0.85) > Hg (0.71), and the concentrations varied spatially and seasonally with relatively higher levels at upward stations and during the rainy season. According to sediment quality guidelines (SQGs), the sediment samples were heavily contaminated with Ag and Hg, and moderately with Co. Threshold effect concentration (TEC) and probable effect concentration (PEC) values indicated that the concentration of only Ni and Cr were likely to occasionally exhibit adverse effects on the ecosystem. Enrichment factor (EF), geo-accumulation index (Igeo) and contamination factor (CF) analyses revealed that Ag, Co and Hg were at moderate to high pollution levels and the rests (As, Cr, Ni, Pb and Mn) were at no to low pollution levels. Potential ecological risk index (PERI) also showed that Ag, Co and Hg were the most potential ecological risk factor being determined in this studied area. Correlation matrix combined with multivariate principal component analysis and cluster analysis suggest that Ag, Co, Ni and Hg originated from anthropogenic sources (agrochemicals, silver nanoparticles anti-microbial agent, silver plating), whereas As, Cr, Pb and Mn primarily originated from natural geological background.

Palaeotoxicity: reconstructing the risk of multiple sedimentary pollutants to freshwater organisms

‘Real-world’ contaminant exposure of sediment-dwelling biota is typically long-term, low-level and to multiple pollutants. However, sediment quality guidelines, designed to protect these organisms, relate only to single contaminants. This study uses radiometrically dated sediment cores from 7 English lakes with varying contamination histories to reconstruct temporal changes in likely risk to biota (herein termed ‘palaeotoxicity’). The Probable Effects Concentration Quotient (PEC-Q) approach was used to combine sediment concentrations from multiple contaminants (trace metals; PCBs; PBDEs) to determine risk allocated to metals and persistent organic pollutants (POPs) separately as well as combined (PEC-Q Mean-All). Urban-influenced lakes were considerably more contaminated, exceeding PEC-Q thresholds of 0.5 and 2.0 over long durations (some since the nineteenth century). This has been mainly due to metals (principally lead) and by factors of up to 10 for individual metals and by > 2 for PEC-Q Mean-Metals. In 6 out of 7 lakes, considerable reductions in risk associated with trace metals are observed since emissions reductions in the 1970s. However, at all lakes, PEC-Q Mean-POPs has increased sharply since the 1950s and at 5 out of 7 lakes now exceeds PEC-Q Mean-Metals. These organic pollutants are therefore now the dominant driver behind elevated contaminant risk to sediment-dwelling biota and recent temporal trends in PEC-Q Mean-All remain above threshold values as a result. Finally, PEC-Q Mean-All values were compared to standard biological toxicity tests for surface sediments at each site. While chironomid growth and daphniid reproduction were significantly reduced compared to controls at 5 out of 7, and all lakes, respectively, the scale of these reductions showed only limited quantitative agreement with predicted risk.

HEAVY METALS CONCENTRATION IN SEDIMENT OF LLUTA RIVER BASIN

Northern Chile is characterized by water scarcity. The Lluta River, located in the XV region of Arica and Parinacota, is the one of the main rivers in northern Chile. The elevated levels of metals and metaloids in the river reduce the agricultural productivity and variety of species can be cultivated within the valley, which are of great importance for the consumption of the inhabitants of the area. Heavy metals in river bottoms may cause various effects on the water quality, as such the capacity to accumulate metals; levels of toxicity and metal stabilization in sediments have often been considered a pollution index of a territory. In this work the concentrations of Al, Cu, Fe, Mn, Mo, Pb and Zn from the pseudo-total and labile fraction of Lluta river sediments were studied. Samples from 10 sites along the river were collected. The sediments were characterized determining: pH, electrical conductivity, organic carbon (OC), organic total carbon (OTC), available phosphorus and boron. Heavy metals were analyzed by Atomic Absorption Spectroscopy (AAS). For the metals analyzed in the pseudo-total fraction, the highest concentrations found were: Al in the site 10, (17061 mg kg -1 ) and Fe on site 6, (29898 mg kg -1 ). For the labile fraction, highest concentrations of metals were: Al in site 6 (1079 mg kg -1 ), Fe in site 9, (275 mg kg -1 ) and Mn in site 9 (1578 mg kg -1 ). Using the Risk assessment code (RAC), the site 6 presents the greatest risk with high values of Cu, Mn, Pb and Zn, followed by site 1 with high values of Mn, Cu and Zn, and site 9 with high values of Mn, Cu and Pb. On the other hand, the MacDonald PEC (probable effect concentration) and TEC (threshold effect concentration) toxicity criteria, showed that the sites 4 and 6 have levels above the TEC for Cu, Fe, Pb and Zn, and levels above the PEC at six sites for Mn.

Multi-contamination (heavy metals, polychlorinated biphenyls and polycyclic aromatic hydrocarbons) of littoral sediments and the associated ecological risk assessment in a large lake in France (Lake Bourget)

The lake littoral sediment is exposed to a large array of contaminants that can exhibit significant spatial variability and challenge our ability to assess contamination at lake scale. In this study, littoral sediment contamination was characterized among ten different sites in a large peri-alpine lake (Lake Bourget) regarding three groups of contaminants: 6 heavy metals, 15 polycyclic aromatic hydrocarbons and 7 polychlorinated biphenyls. The contamination profiles significantly varied among sites and differed from those previously reported for the deepest zone of the lake. An integrative approach including chemical and biological analyses was conducted to relate site contamination to ecological risk. The chemical approach consisted in mean PEC quotient calculation (average of the ratios of the contaminants concentration to their corresponding Probable Effect Concentration values) and revealed a low and heterogeneous toxicity of the contaminant mixture along the littoral. Biological analysis including both laboratory (microcosm assays) and in situ (Acetylcholine Esterase (AChE) and Glutathione S-Transferase (GST) activity measurements) experiments highlighted significant differences among sites both in the field and in laboratory assays suggesting a spatial variation of the biota response to contamination. Linear regressions were performed between mean PEC quotients and biological results to assess whether littoral ecological risk was explained by the contamination profiles. The results highly depended on the study benthic or pelagic compartment. Regarding autochthonous Corbicula fluminea, no significant relationship between mean PEC quotients and biomarker activity was found while a significant increase in AChE was observed on autochthonous chironomids, suggesting different stress among benthic organisms. Both AChE and GST in caged pelagic Daphnia magna showed a significant positive relationship with mean PEC quotients. This study underlines the importance of accounting for spatial variations in lake littoral sediment contamination and the need for performing an integrative approach coupling chemical, field and laboratory analyses to assess the ecological risk.

Assessment of metal pollution in the Lambro Creek (Italy)

This study assessed the effect of metal pollution in the Lambro Creek (Southern Italy). Water, sediment and biota were collected at six sampling sites (June) for metal concentration assessment (Cr, Cu, Ni, Pb and Zn). Sequential extraction was performed to determine the distribution of metals in different geochemical sediment fractions. The influence of pH and leaching time on the release of metals from sediment to the water column was investigated via remobilization tests. A battery of toxicity tests (Vibrio fischeri, Raphidocelis subcapitata, Phaeodactylum tricornutum, and Daphnia magna) with multi-endpoints (bioluminescence, growth inhibition, and immobilization) was used to determine the overall toxicity in sediment water extracts. The results showed that metals did not exceed the probable effect concentration levels, with Cr concentration exceeding the threshold effect concentration level at all sampling points except for the one closer to the source of the creek, suggesting potential negative effect on the biota. Considering the cumulative criterion unit, sediment contamination was moderate at all sampling sites, except for L3 and L5 where biota was exposed to a very high risk. With respect to sequential analysis, the most readily available fraction of metal can be generalised as Ni > Cr > Cu > Zn > Pb. For better understanding the fate of metals in the water-sediment environment, their biogeochemical cycles should also be investigated in small creeks including both fresh (watercourse) and saltwater (river mouth) sediments.