Use of Sediment Quality Guidelines & Related Tools for the Assessment of Contaminated Sediments
... Although agriculture is critically important in supporting a growing human population, it is also important to maintain the environmental integrity of downstream aquatic systems. Understanding the extent and impact of agricultural contaminants in river and stream sediments is a valuable step in finding mitigation strategies that effectively improve and/or maintain aquatic ecosystem services [2][3][4]. ...
... Twenty-eight-day whole surface sediment toxicity bioassays using H. azteca were conducted per 1 L sample according to modified USEPA protocols [4,15]. Bioassays were comprised of treatments of sieved sediment from three habitats (upstream, midstream, downstream) within each bayou (Cow Oak, Howden, Roundaway) collected seasonally (winter, spring, summer, fall) during three-year study period. ...
... Overlying water quality parameters associated with a 28-day amphipod sediment bioassay were within acceptable limits as prescribed by USEPA protocol [4,15]. Measured water quality data, mean and ranges, were as follows. ...
Agricultural activity enhances topsoil erosion and facilitates the transport of pesticides that alter watershed sediment quality. Agricultural stream (bayou) sediment quality in Mississippi, USA, was evaluated across three bayous, habitats (upstream, midstream, downstream), and seasonally from 2011 to 2014 for pesticide contamination, effects, and bioavailability to Hyalella azteca. Four-week (28-day) H. azteca sediment bioassays were conducted to assess survival and growth and tissue residues. Fourteen pesticides were detected in at least one sediment sample and nine pesticides were detected in H. azteca tissues. Sediment pesticides p,p’-DDT and p,p’-DDE were greatest in Cow Oak Bayou and heptachlor and bifenthrin were greatest in Howden Lake Bayou. Seasonally, λ-cyhalothrin and p,p’-DDT were greatest in winter while trifluralin, atrazine, and clomazone were greatest in the fall. H. azteca survival and growth ranged from 0 to 100% and 0.8–4.1 mg, respectively, with Cow Oak, downstream habitats, and spring samples having the greatest survival and growth. Greatest tissue pesticide residues were atrazine (1271 µg/kg), p,p’-DDT (1,093 µg/kg), and β-cyfluthrin (1003 µg/kg). Tissue pesticide residues were influenced primarily by p,p’-DDT with Cow Oak and fall tissue samples having the lowest residues. H. azteca tissue p,p’-DDT residues contributed to biological impairment. Although banned in the USA for 40 years, p,p’-DDT continues to impact sediment quality.
... The model results were validated by assessing the contamination levels of As, Cr, Cu, Fe, Mn, Ni, Pb, and Zn taken from samples collected from upstream, midstream and downstream of four tributaries of the Olifants River Basin during a previous study [75] ( Table 7). The observed contamination levels of the trace metals were compared with the permissible international levels for waterbodies as per the sediment quality guidelines [76,77]. The overall assessment indicated extremely elevated levels of As, Cr, Mn, and Ni, and some samples were severely enriched and extremely contaminated with As, Cr, and Ni [75]. ...
... Average pollutant concentrations in the Olifants River and the average shale values and sediment quality guidelines (SQG) values.Note(s): * Turekian and Wedepohl[77]; SQG, Sediment Quality Guideline[76]. Source: Addo-Bediako[75]. ...
Wetlands are critical ecological infrastructures that improve water quality, serve as habitat for fish and other aquatic life, accumulate floodwaters, and maintain surface water flow during dry periods. However, the health of wetlands has been compromised by anthropogenic activities that affect the constant supply of ecosystem services. This study assessed the impact of anthropogenically modified land use on wetland health in the Witbank Dam Catchment in South Africa, whose land use has been severely modified for agriculture and mining purposes. The study developed a model linking surface runoff generated in the catchment with land use and wetland typology to comprehend diffuse pollution from pollution-source land uses. Runoff data and related wetland spatial information were processed and analysed in a Geographic Information System (GIS) to estimate pollutants (agricultural nutrients and acid mine drainage) from runoff detained and released by wetlands. The analysis facilitated the assessment of the value of wetlands in enhancing water quality, as well as human and environmental health. The runoff volume from pollution-source land uses (urban areas, farmlands, and mining) was used to evaluate annual pollution levels. Wetland types are ranked according to their efficiency levels to filter pollutants. The assumption is that the difference between filtered and unfiltered runoff is the quantity of polluted runoff water discharged into the river system. The analysis has shown that 85% of polluted runoff generated in the catchment ends up in the river system. An important observation is that although wetlands have a substantial ability to absorb excess pollutants, they have finite boundaries. Once they reach their full holding capacity, they can no longer absorb any further pollutants. The excess is discharged into the river system, risking human and environmental health. This explains why the Limpopo River is heavily polluted resulting in the death of fish, crocodiles and other aquatic life.
... Originally, they provided the information on SQGs compared with a reference or background concentration of analysed substances [76]. After the 1980s, SQGs were developed to evaluate sediment quality where harm to aquatic organisms and the environment was observed [77]. In general, SQG approaches that use different criteria and factors are divided into two main categories [76]: ...
... Sediment quality guidelines (SEQs) for TMs and metalloid in mg/kg d.w. that reflect threshold effect concentration (TEC) and probable effect concentration (PEC)[77][78][79][80][81][82].Empirical SQGs with TEC and PEC in mg/kg·d.w. ...
This paper provides an overview of different methods of assessing the trace metal (TM) contamination status of sediments affected by anthropogenic interference. The geochemical background determination methods are also described. A total of 25 papers covering rivers, lakes, and retention tanks sediments in areas subjected to anthropogenic pressure from the last three years (2019, 2020, and 2021) were analysed to support our examination of the assessment measures. Geochemical and ecotoxicological classifications are presented that may prove useful for sediment evaluation. Among the geochemical indices, several individual pollution indices (CF, Igeo, EF, Pi (SPI), PTT), complex pollution indices (PLI, Cdeg, mCdeg, Pisum, PIAvg, PIaAvg, PIN, PIProd, PIapProd, PIvectorM, PINemerow, IntPI, MPI), and geochemical classifications are compared. The ecotoxicological assessment includes an overview of Sediment Quality Guidelines (SQG) and classifications introduced nationally (as LAWA or modified LAWA). The ecotoxicological indices presented in this review cover individual (ERi) and complex indices (CSI, SPI, RAC, PERI, MERMQ). Biomonitoring of contaminated sites based on plant bioindicators is extensively explored as an indirect method for evaluating pollution sites. The most commonly used indices in the reviewed papers were Igeo, EF, and CF. Many authors referred to ecotoxicological assessment via SQG. Moreover, PERI, which includes the toxic response index, was just as popular. The most recognised bioindicators include the Phragmites and Salix species. Phragmites can be considered for Fe, Cu, Cd, and Ni bioindication in sites, while Salix hybrid cultivars such as Klara may be considered for phytostabilisation and rhizofiltration due to higher Cu, Zn, and Ni accumulation in roots. Vetiveria zizanoides demonstrated resistance to As stress and feasibility for the remediation of As. Moreover, bioindicators offer a feasible tool for recovering valuable elements for the development of a circular economy (e.g., rare earth elements).
... This paper contends that the relative influences of true effects, random variation, and confounding may go unrecognized, unseparated in the derivation of benchmarks, or may not be adequately communicated to users. The evaluation of sample size on the reliability of empirical benchmarks complements the findings from a Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop on Use of Sediment Quality Guidelines and Related Tools for the Assessment of Contaminated Sediments (Wenning et al., 2005). Fifty-five experts from North America, Europe, and Australia met for six days to review existing guidelines (or benchmarks) from around the world, assess strengths and limitations, and provide recommendations on framework and approaches that incorporate predictive and empirically derived concentration values in sediment. ...
... Threshold calculation methods like ERL try to isolate components of these mixtures and draw causal inferences about the individual components, but those components were not sampled in isolation or controlled in a laboratory experiment, and they are present in different sample sizes across mixture components. This is currently well understood as a limitation of such guidelines (Wenning et al., 2005). What has not been explored are the possible magnitudes of error associated with the derived values and the possibility that less toxic chemicals can be found to be toxic by association with other stressors in the sample. ...
Tabulations of numerical concentration-based environmental benchmarks are commonly used to inform decisions on managing chemical exposures. Benchmarks are usually set at levels below which there is a low likelihood of adverse effects. Given the widespread use of tables of benchmarks, it is reasonable to expect that they are adequately reliable and fit for purpose. The degree to which a derived benchmark reflects an actual effect level or statistical randomness is critically important for the reliability of a numerical benchmark value. These expectations may not be met for commonly-used benchmarks examined in this study. Computer simulations of field sampling and toxicity testing reveal that small sample size and confounding from uncontrolled factors that affect the interpretation of toxic effects contribute to uncertainties that might go unrecognized when deriving benchmarks from data sets. The simulations of field data show that it is possible to derive a benchmark even when no toxicity is present. When toxicity is explicitly included in simulations, imposed effect threshold levels could not always be accurately determined. Simulations were also used to examine the influence of mixtures of chemicals on the determination of toxicity thresholds of chemicals within the mixtures. The simulations showed that data sets that appear large and robust can contain many smaller data sets associated with specific biota or chemicals. The sub-sets of data with small sample sizes can contribute to considerable statistical uncertainty in the determination of effects thresholds and can indicate that effects are present when they are absent. The simulations also show that less toxic chemicals may appear toxic when they are present in mixtures with more toxic chemicals. Because of confounding in the assignment of toxicity to individuals chemicals within mixtures, simulations showed that derived toxicity thresholds can be less than the actual toxicity thresholds. A set of best practices is put forward to guard against the potential problems identified by this work. These include conducting an adequate process of determining and implementing Data Quality Objectives (DQOs), evaluating implications of sample size, designing appropriate sampling and evaluation programs based on this information, using an appropriate tiered evaluation strategy that considers the uncertainties, and employing a weight of evidence approach to narrow the uncertainties to manageable and identified levels. The work underscores the importance of communicating the uncertainties associated with numerical values commonly included in tables for screening and risk assessment purposes to better inform decisions.
... SQGs were reviewed in the derivation of screening values for Hong Kong (Chapman et al., 1999a(Chapman et al., , 1999b and in the implementation of equilibrium partitioning by the US EPA (McCauley et al., 2000). Workshops to review SQGs were conducted in 2000 (GIPME, 2000) and 2005 (Wenning et al., 2005) amongst others. Methods, advantages, assumptions and limitations in the use of SQGs for chemical mixtures were provided by Long et al. (2006) and SQGs were reviewed for global use by Burton (2002). ...
... A variety of sediment chemistry-based approaches has been developed from empirical and mechanistic relationships (Wenning et al., 2005;OSPAR, 2008) to assess risk of adverse effects to benthic communities. In the current work, schemes based on matching chemical and biological data are grouped into Empirical (correlative) Approaches, while Mechanistic Approaches, founded on equilibrium partitioning (EqP), address factors controlling bioavailability, chemical uptake and toxicity, i. e. provide a theoretical basis for an understanding of cause and effect. ...
This review of 19 chemical approaches used in assessing sediment quality are classified into empirical, mechanistic and sediment quality indices (SQI) groups. Empirical sediment quality guidelines (SQGs), based on matching chemical and biological-effects data and the mechanistic techniques, founded on equilibrium partitioning principals (EqP), are well established and most used. Empirical SQGs provide a useful screening tool to initially identify locations and chemicals of most concern, but are not regulatory criteria. The EqP approach is causally linked however, the scheme assumes porewater chemistry largely controls sediment toxicity. SQIs are not based on matching chemical-biological data and combine schemes with multiple narrative intents. The 41 SQGs reviewed show a considerable range in upper and lower guideline values. Grain size and organic content should be included into SQGs, however inclusion of suspended sediment into SQGs raises concerns. SQGs are built into decision-tree schemes with other lines-of-evidence and evaluated in a weight-of-evidence framework.
... However, overall sediment pass/fail outcomes using different AL sets with the same narrative intent (e.g., AL1, AL2) do not differ nearly as much as outcomes using different chemical action lists and decision rules (Apitz et al., 2007, Apitz, 2008, 2011Wenning et al., 2005;Apitz and Agius, 2013). The "Consensus" AL1 values used here provide a consistent set of hypothetical ALs for the full suite of contaminants in this study; they should not be regarded as regulatory proposals. ...
... This assumption is necessary to provide some basis of comparison, but the toxicity measures themselves contain uncertainty. Bioassessment can be subject to a range of confounding factors, and may be sensitive to unmeasured contaminants in the sediments; errors or mis-classifications can occur in any measurement (Apitz 2011;Wenning et al. 2005). Scenarios using mHQ filters to evaluate the possibility that sediments failing a single sub-lethal assessment (not described here but results in Table S1-3) suggest that some proportion of sediments classified as sub-lethally toxic (i.e., failing one sub-lethal test) could be the result of confounding factors (the authors were able to confirm that hydrogen sulphide toxicity, which has a strong confounding effect in Microtox™ bioassays done using solvent extracts, was unlikely to be the culprit since standard procedures used in the National Status and Trends Program require the removal of hydrogen sulphide prior to solvent extraction (Long et al., 1999). ...
The effects of possible changes to the Canadian 2-tiered assessment framework for dredged material based on outcomes of the 2006 Contaminated Dredged Material Management Decisions Workshop (CDMMD) are evaluated. Expanding on the “data mining” approach described in a previous paper, which focused solely on chemical lines of evidence, the efficacy of Tier 1 approaches (increases to the number of chemical analytes, use of mean hazard quotients, and the use of a screening bioassay) in predicting toxicity are evaluated. Results suggest value in additional work to evaluate the following areas: 1) further expanding minimum chemical requirements, 2) using more advanced approaches for chemical interpretation, and 3) using a screening-level bioassay (e.g., Canadian solid-phase photoluminescent bacteria test) to determine whether it would complement Tier 1 chemistry as well as or better than the solvent-based Microtox™ test method evaluated in the present study. Integr Environ Assess Manag 2017;13:1072–1085. © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)
Key Points
We developed a sediment database to examine international dredged material assessment approaches. A longer chemical action list is more effective at predicting toxicity. Well-designed mean hazard quotient approaches outperform “one out/all out” rules. A conservative Tier 1 screening bioassessment improved toxic detection.
... The concentrations of Mn in both the banks of the river were below their background value (i.e., 460 mg/kg) and showed no significant increase in concentration from the right to left banks of the river. Similarly, the concentration of Zn, Cu, and Fe is found below the maximum admissible concentrations as recommended by (Wenning et al. 2002;USEPA 2009) and also lower than average shale, threshold effect level (TEL), and portable effect level (PEL) values (Table 1). Relatively, narrow dispersion of these metals was noted in sediments among both banks (left and right) of the river. ...
... The results of Mn, Fe, Zn, and Cu in the study area are consistent with those reported by Nazeer et al. (2014) in the Soan River. In the study area, Pb content in sediment samples of the left bank of the river was slightly higher than regulatory limits of interim sediment quality guideline (ISQG) (Wenning et al. 2002;USEPA 2009), i.e., 35.8 mg/kg. The maximum concentration (72.0 mg/kg) of Pb was found in the samples collected from the left bank on the downstream of the river. ...
To assess the trace metal pollution in the Siran River, sediments were collected from 12 sites, from the left and right banks of the river in 2013. The concentrations, accumulation, distribution pattern, and pollution status of heavy metals in sediments were investigated using geoaccumulation index (Igeo) and enrichment factor (EF). The toxic risk of heavy metals was assessed using interim sediment quality guidelines (ISQGs), portable effect level (PEL), threshold effect level (TEL), and toxic effect threshold (TET). Igeo and EF values showed that sediments were loaded with Ni, Cd, Pb, and Co and no obvious variations were found among the left and right banks of the river. The EF and Igeo values were found in order of Co > Pb > Ni > As > Cd > Cu > Zn > Fe and Cd > Co > Pb > Ni > As > Fe > Zn > Cu > Mn, respectively. Furthermore, multivariate statistical analysis like inter-metal correlation, cluster analysis (CA), and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of sediment contamination in the study area. These results indicated that more attention should be paid to the inner loads of sediment in order to achieve improvements in reservoir water quality after the control of external pollution.
... Contaminated sediments pose large problems for coastal waters in need of constant dredging; their management is controlled by the London Convention and various national legislation. The science of evaluating sediment-bound contaminants is described in Dickson et al. (1987), National Research Council (1989b, Baudo et al. (1990), Burton (1992), Ingersoll et al. (1997), Stolzenbach and Adams (1998) and Wenning (2005), among others. After many conferences and discussion, there is general agreement about the choice and application of the suites of bioassay tests to use, for both freshwater and marine environments. ...
... Much of the work is conducted on sediments contaminated by oil spills, polluted harbours and pulp-mill discharges. The uptake of sediment-borne contaminants, influence on bioavailability of influencing factors, relationships between sediment contamination and toxicity and the standardization and quality control of methods have received considerable attention (Power and Chapman, 1992;Lamberson et al., 1992;Wenning, 2005). ...
Contents:
A Short History of Aquatic Toxicology
The Aquatic Environment
Factors that Affect the Environmental Concentration of Chemicals
Basic Toxicological Concepts and Principles
Factors that Influence Toxicity
Toxic Agents and Their Effects
Examination of Concentration-Response Relationships
Toxicity Testing
Interpreting Toxicity Test Data
Biomonitoring
Toxicity Dada and Environmental Regulations
... In addition, Sediment Quality Guidelines (SQGs) were used for evaluating sediment quality considering that they are well-established tools to outline the range of pollutant concentrations (Wenning and Ingersoll, 2002). Both empirical and theoretical approaches have been considered for developing SQGs. ...
Full-text access: https://authors.elsevier.com/a/1hqpHB8ccyf4B Pollution of surface waters is a global threat, with particular concern about pesticides due to their severe negative effects on ecosystem functioning and human health. The aims of this study were to identify the spatiotemporal patterns of water and sediment quality, and the key variables related to the variation in pesticide pollution, in headwater streams (surrounding land uses: crop or mixed crop-livestock systems) and floodplain streams (surrounding land uses: urban development or natural wetland) of the Paraná River basin in the central area of Argentina. We found significant differences in water and sediment quality related to local land uses among headwater streams, but not among floodplain streams. These differences were more noticeable during spring than during autumn. Pesticides were widespread in all the streams, independently of the surrounding land use, reflecting the combination of local inputs and the role of floodplain hydrological connectivity in transporting pollutants from upstream sources. The most frequently detected compound was atrazine (75 %), whereas the highest concentration of an individual compound was observed for the glyphosate metabolite aminomethylphosphonic acid (AMPA, up to 4 μg L−1). The significant explanatory variables for pesticide pollution were turbidity, chromophoric dissolved organic matter (CDOM), sub-basin area, side slope of streams (positive relations), wetland cover, and precipitations (negative relations). Our results can be useful for the design of monitoring programs that capture the spatial and temporal variability of pesticide pollution.
... However, if TEC ≤Mean concentrations ≤PEC, the potential risk cannot be ascertained from heavy metal concentrations alone. In addition, cumulative toxicities of the metals can be estimated by mPECq [28] and calculated as in Equation (4). Sediment is defined as toxic if mPECq>0.5 and non-toxic if mPECq <0.5 [27]: ...
... This subsequently makes it difficult to detect, quantify or pin-point a specific pollutant at a given contamination site. Challenge is therefore to accurately assess the impacts of the pollutants as well as the remediation measures undertaken (Burton Jr, 1991;Wenning et al., 2005). The use of sediment cores for sample collection has been commonly practiced for analyzing contamination in streambeds Van Metre et al., 2003;Brinkmeyer et al., 2015). ...
Streambeds are an integral part of the river ecosystems. They provide habitat to a vast array of aquatic and benthic organisms as well as facilitate the bio-degradation and transformation of organic matter and vital nutrients. Increasing anthropogenic influence introduces multiple stressors to the stream networks resulting in pollution of streambeds, which in turn, have detrimental effects on the overall stream ecosystem health. There is a huge gap in the current understanding of streambed pollution and its impacts, and the widely practiced streambed pollution mitigation strategies lack a holistic approach. In this comprehensive review, we first synthesize the state-of-the-art knowledge of conventional and emerging forms of contaminants, their overall impacts on stream ecosystem functions, and present future directions to comprehend the problem of streambed pollution. We highlight that fine sediments and plastics (found especially in urban streambeds) are among the major physical pollutants causing streambed pollution and the chemical pollutants generally comprise hydrophobic compounds including various legacy contaminants such as polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT), a wide range of pesticides and a variety of heavy metals. Moreover, in recent years, highly polar and hydrophilic emerging contaminants such as micro-plastics, pharmaceutical waste and personal care products have been identified in riverbeds and streambeds across the world. We stress that the impacts of streambed pollution have been largely studied with discipline-driven perspectives amongst which the ecological impacts have received a lot of attention in the past. To present a comprehensive outlook, this review also synthesizes and discusses some of the understudied hydrological, geomorphological and biochemical impacts of different forms of streambed pollution. Subsequently, we also present a global inventory by compiling information from the published literature to highlight the status of streambed pollution around the globe. In the end, we endorse the positive and negative aspects of the current impact assessment methodologies and also highlight various physical, chemical and biological remediation measures that could be applied to alleviate streambed pollution.
... Hence, it is important to protect sediments from the impacts of contamination to preserve functional ecosystems. The intent of most Sediment Quality Guideline Values (SQGVs) is to provide a concentration below which the risk of adverse effects to aquatic organisms will be negligible (Wenning et al., 2005;Simpson and Batley, 2016). Many SQGVs used globally have been derived using a similar approach, i.e., using relationships between contaminant concentrations in field-collected sediments and observations of differences in ecology (e.g. ...
The derivation of sediment quality guideline values (SQGVs) presents significant challenges. Arguably the most important challenge is to conduct toxicity tests using contaminated sediments with physico-chemistry that represents real-world scenarios. We used a novel metal spiking method for an experiment that ultimately aims to derive a uranium SQGV. Two pilot studies were conducted to inform the final spiking design, i.e. percolating a uranyl sulfate solution through natural wetland sediments. An initial pilot study that used extended mixing equilibration phases produced hardened sediments not representative of natural sediments. A subsequent percolation method produced sediment with similar texture to natural sediment and was used as the method for spiking the sediments. The range of total recoverable uranium (TR-U) concentrations achieved was 8–3200 mg/kg. This reflected the concentrations found in natural wetlands and water management ponds found on a uranium mine-site and was above natural levels. Dilute-acid extractable uranium (AE-U) concentrations were >80% of total concentrations, indicating that much of the uranium in the spiked sediment was labile and potentially bioavailable. The portion of TR-U extractable as AE-U was similar at the start and end of the 4.5-month field-deployment. Pore-water uranium (PW–U) analyses indicated that partition coefficients (Kd) were 2000–20,000 L/kg, and PW-U was greater in post-than pre-field-deployed samples when TR-U was ≤1500 mg/kg, indicating the binding became weaker during the field-deployment period. At higher spiked-U concentrations, the PW-U was lower post-field-deployment. Comparing the physico-chemical data of the spiked sediments with environmental monitoring data from sediments in the vicinity of a uranium mining operation indicated that they were representative of sediments contaminated by mining and that the U-spiked sediments had a clear U concentration gradient. This confirmed the suitability of the spiking procedure for preparing sediments that were suitable for deriving a SQGV for uranium.
... In the present work, the total chemical analysis of the sediment fine fraction smaller than 63 µm was considered to be an adequate estimate of exposure. Adjustments to account for bioavailability or chemical speciation can improve exposure estimates (Wenning et al. 2005;Alvarez-Guerra et al. 2010;Lécrivain et al. 2018). To determine the potential mobility, bioavailability and toxicity of the elements examined, more extensive studies including the analysis of element speciation, as well as the temporal variability in the sediments' characteristics, are proposed. ...
Purpose
The Limoncocha lagoon, inside a Ramsar site in the Ecuadorian Amazon, increasingly hosts ecotourism and energy development activities. This work estimates the local sediments’ baseline of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V and Zn using four methods. This makes it possible to apply single and integrated pollution indices to estimate the contamination level and the ecological risk of the sediments.
Methods
Seven sites were analysed for metal(oid)s by ICP-MS. The local baseline was estimated using the relative cumulative frequency method, the iterative 2σ- and 4σ-outlier-techniques and the normalisation method to a “conservative” element. Combinations of single Cf and Ef and integrated indices (NPI, mNPI, mCd, MEQ, RI, mPELq, mERMq and TRI) were applied.
Results
The relative cumulative frequency method had the best performance for the geochemical baselines. Cf and Ef indices classify sediments from a “low contamination” remote site to the “moderate contamination” and “minor enrichment” of the remaining sites due to As, Cd and Zn concentrations. The overall analysis of the integrated indices results in Ni, Zn and Cu being identified as priority pollutants because they have occasionally been associated with adverse biological effects in the centre of the lagoon and in the most anthropised areas. These are classified as moderately polluted with a medium–low priority risk level.
Conclusions
This work provides sediment baseline and contamination indicators for pollutants, which could be incorporated into the sediment quality assessment and monitoring programme of the Limoncocha lagoon. Ni, Cd and Cr due to the high baseline values in comparison with SQGs, and Cu and Zn due to their potential risk, should be of special attention.
Graphical abstract
... Ecological risk indices are being a major screening tool to potentially identify, rank, and prioritize significant toxic metals or contaminants in a system. There are several geo-chemistry-based empirical and mechanistic approaches to evaluate the potential risk of benthic sediment dwellers (Wenning, 2005;Birch, 2018). But, when indices are applied, the role of individual metals or contaminants to the overall risks was reduced because the approaches average the multiple toxic concentrations. ...
Mangrove sediment acts as a natural accumulator of potentially toxic metals (PTMs). Here, we have investigated the efficiency of mangrove species e.g. Sonneratia caseolaris and Avicennia officinalis phytoremediation potential in a globally significant vulnerable river. The lower pH and anoxic conditions facilitate the elevated accumulation of PTMs in river Hooghly. The presence of PTMs in fine sediment fraction in greater proportion indicates a larger role of fine-grained silt and clay particles in the accumulation process. The estimated sediment quality indices indicate no significant change in the last thirty years. However, the ecotoxicological indices suggest a low level of ecological risks but can turn toxic because of the gradual accumulation of metals. The accumulations of PTMs in mangroves are regulated by the metal bio-availability. The result emphasizes mangrove pneumatophores, as a greater accumulator of PTMs than mangrove leaves. Higher translocation factors also indicate the applicability of mangroves as a phytoremediator of contaminated sediment.
... This subsequently makes it diffi-cult to detect, quantify or pin-point a specific pollutant at a given contamination site. Challenge is therefore to accurately assess the impacts of the pollutants as well as the remediation measures undertaken [187,188]. The use of sediment cores for sample collection has been commonly practiced to analyze the streambed pollution [38,42]. ...
Streambeds are among the important components of stream ecosystems and support several critical ecosystem services such as transformation of organic matter and nutrients and provide habitat for aquatic organisms. Increasing anthropogenic influence introduces multiple stressors to the stream networks resulting in pollution of streambeds, which in turn, could have detrimental effects on overall stream ecosystem health. However, there are gaps in the current understanding of the impacts of streambed pollution and the mitigation strategies lack holistic approach. In this review, we first present a global inventory to highlight the status of streambed pollution around the globe. Next, we synthesize the state-of-art knowledge of conventional and emerging forms of contaminants, their overall impacts on stream ecosystem functions, and finally present future directions to comprehend the problem of streambed pollution. We highlight that fine sediments and plastics (found especially in urban streambeds) are among the major physical pollutants of streambed pollution and the chemical pollutants generally comprise of hydrophobic compounds including various legacy contaminants such as polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT), a wide range of pesticides and a variety of heavy metals. Further, in recent years, highly polar and hydrophilic emerging contaminants such as micro-plastics, pharmaceutical waste and personal care products have been identified in rivers around the world. We stress that the impacts of streambed pollution have been largely studied with discipline-driven perspectives amongst which the ecological impacts have received a lot of attention in the past. To present a comprehensive outlook, this review also synthesizes the hydrological, geomorphological and biochemical impacts of different forms of streambed pollutants. In the end, we endorse the positive and negative aspects of the current impact assessment methodologies and also highlight various physical, chemical and biological remediation measures that could be applied to alleviate streambed pollution.
... SQGs were often employed to assess the intensity of biological effects of heavy metals in sediments. In SQGs, adverse biological effects of heavy metals are unlikely to happen when the heavy metal concentrations are lower than the threshold effect concentrations (TEC), while adverse biological effects are expected to happen when the heavy metal concentrations are higher than the probable effect concentrations (PEC) (MacDonald et al., 2000;Wenning et al., 2005). ...
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.
... For example, the interactions between the sediment and the overlying water affect the contaminants' mobility, and the effects of the contaminant might be affected by an unknown mixture of additional contaminants and conditions (Apitz 2005;Bridges et al. 2006). Therefore, it is suggested that SQG can be used to indicate very low or very high risks of toxicity to organisms but not to state whether toxicity is possible or impossible (Wenning et al. 2002;O'Connor 2004). The complexity of assessing contaminated sediments might warrant several LOEs to assess the ecological implications of the contaminants of concern. ...
Several countries currently lack common recommendations specific to Ecological Risk Assessment (ERA) of contaminated sediments and stakeholders report inconsistencies between currently used approaches. The objective of this study was to provide an increased understanding of how ERAs of contaminated sediments are conducted in comparison to established guidelines. For this, we use Sweden as a case study and compare seven ERAs with four internationally established strategies. Our results indicate that contaminant concentrations receive a comparatively high weight, despite a lack of appropriate benchmarks; toxicity measurements are uncommon, while routine in established strategies; and the integration and interpretation of results lack transparency. We identify three areas that may help improve the practice of ERAs: a common approach to benchmarks, recommendations for how to assess toxic effects, and a common approach for integrating and interpreting results.
... DelValls et al. (2004) have reviewed SQGs from different European countries and have shown that they differ by two orders of magnitude for some substances (e.g., As, Cu, and seven PCBs). Most of the limitations listed and discussed at the Pellston Workshop on "use of sediment quality guidelines and related tools for the assessment of contaminated sediments" in 2002 have not been addressed to date for existing SQGs; e.g., they deliver no or limited information on the ecologically important aspects of chronic toxicity to sediment-dwelling organisms and causeeffect relationships, in addition to the questionable transferability of SQGs, derived from one endpoint in the laboratory, to, e.g., effects on organisms in the environment (Wenning et al. 2005). Moreover, existing SQGs cover tens of substances at best, and therefore substances of emerging concern cannot be reliably assessed with this tool. ...
Purpose
Basing decisions for the management of contaminated sediments on ecotoxicological data is still often met with skepticism by European stakeholders. These concerns are discussed as they pertain to bioassays to show how ecotoxicological data may provide added value for the sustainable management of sediment in aquatic systems.
Materials and methods
Five “concerns” are selected that are often raised by stakeholders. The ecotoxicological practice is discussed in light of the knowledge gained in recent decades and compared with chemical sediment analysis and chemical data.
Results and discussion
Common assumptions such as a higher uncertainty of biotest results for sediments compared to chemical analyses are not supported by interlaboratory comparisons. Some confusion also arises, because the meaning of biotest data is often misunderstood, questioning their significance in light of a limited number of organisms and altered test conditions in the lab. Because biotest results describe a sediment property, they should not be directly equated with an impact upon the biological community. To identify a hazard, however, the possibility of false-negative results due to the presence of contaminants that are not analyzed but are toxic is lower.
Conclusions
The cost of increased investment in ecotoxicological tests is, in our view, small compared with that of making false-negative assessments of sediment/dredged material that can ultimately have long-term environmental costs. As such, we conclude that ecotoxicological testing is an opportunity for sediment management decision-making that warrants more attention and confidence in Europe.
... The element concentrations were compared with the sediment quality guidelines (SQGs) (McCauley et al. 2000). Effects range low (ERL), effects range median (ERM), threshold effects level (TRL), and probable effects level (PEL) are commonly used to evaluate the sediment quality and its effect on the biological community (Macdonald et al. 1996;Wenning 2005). The elements having concentrations below ERL and TEL values suggest rare or occasional adverse biological effects on the biota, while above ERM and PEL suggest frequent adverse effects on biota (Zahra et al. 2014;Sarkar 2018). ...
Chilika lake, the largest brackish water lagoon in Asia, has a unique setting, where the northeastern part receives freshwater from the terrestrial runoff, and the southeastern part receives seawater from the Bay of Bengal. The seasonal variability in the quantity of inflowing water and their mixing in the lake controls the mobilization and precipitation of various elements. Seasonal sediment samples were collected from both the river and seawater influenced regions of the lake to understand the spatio-seasonal distributions of various elements along the salinity gradient. The major elements present in the sediments are mostly derived from the parent rock weathering in the source region and subsequently transported into the lake by the rivers. Seasonal variations in trace element concentrations are more prominent in the northeastern part of the lake (i.e., low salinity region), and their higher concentrations have been observed during the post-rainy period. The affinity of the elements (Al, Fe, Mn, Li, V, Co, Cr, Cu, Th, and Zn) towards fine-grain sediments suggests that the size distribution pattern controls their accumulation, retention, and remobilization. The concentrations of Cr, Cu, and Pb exceeded the effects range low, and effects range median benchmarks indicating the potential biological risk in the low salinity region as compared to the high salinity region. The statistical analysis indicated that the concentrations of elements in the region proximal to the sea mouth are controlled by grain size and physicochemical condition of the lake water. In contrast, the element concentrations in the interior region are associated with anthropogenic activities and weathering processes. Continuous monitoring and assessment of element concentrations of the lake sediments can help to protect the lake ecology from the harmful element contaminations.
... Owing to the lack of reference values for assessing environmental status in anthropized marine coastal areas, with the only exception of the Environmental Quality Standards (EQS) for sediments (D.M. 56/09, D.M. 260/10), as defined by the Italian Government according to 2000/60/CE, but not applicable for impacted areas, ICRAM defined site-specific "action levels" according to the current scientific literature (Burton, 2002;Wenning et al., 2005;den Besten, 2007) and the main approaches already applied by the USA (U. S. Environmental Protection Agency, 1996Agency, , 1997, Canada (CCME, 2001;Macfarlane and MacDonald, 2002), and Europe (van de Meent et al., 1990;Ospar Commission, 2004a,b), taking into account the peculiar geochemical characteristics along the Italian coast. ...
In the first decades of 2000s, several Italian sites affected by strong anthropogenic impact were recognized as Sites of National Interest (SINs) for a successive reclamation project, some of which also including marine sectors. These coastal areas are characterized by high complexity and diversity as regards the natural setting as well as for extent, history, type, and degree of contamination. For this, the Italian Ministry of Environment charged its scientific research Institute (earlier ICRAM, now ISPRA) with planning a flexible, adaptable, and large-scale environmental characterization. In this context, the investigation of marine sediments was identified as the primary target to assess the environmental status, because of their conservative capacity with respect to contaminants and their role in the exchange processes with other environmental matrices, such as water column and aquatic organisms. A multidisciplinary, chemical–physical, and ecotoxicological survey was identified as the most appropriate and objective criterion for assessing the sediment quality associated, when necessary, with integrative studies. The results derived from this multidisciplinary approach highlighted the main sources of contamination, together with size and extent of the environmental impact on the coastal marine areas, strictly correlated with the kind of anthropogenic activities and coastal morphology. In order to underline how the different environmental setting influences the degree of anthropogenic impact, four different case studies, selected among the more complex by geochemical and geomorphological viewpoints and more extensively studied, were considered. A comprehensive evaluation of these case studies allowed to deduce some general principles concerning the effects of anthropogenic impact, which can be applicable to other transitional and marine coastal areas.
... Sediment characteristics influence the effectiveness of treatment technologies (US EPA, 1994;Vallero, 2010). Specific chemical and physical properties are used to describe a sediment sample: grain size, grain density, water content, total organic matter (TOM), buffering capacity, carbonates, geotechnical and agronomic properties (Batley et al, 2005). Water content, TOM content, dry bulk density and porosity affect basic sediment characteristics such as diffusion properties and mechanical properties, as well as the microbial metabolic rates (Avnimelech et al, 2001). ...
... Il apparaît donc fondamental d aborder la gestion des sédiments suivant une approche durable, ce qui n est pas le cas pour la plupart des projets de gestion actuels (Apitz, 2012 (Wenning et al., 2005;Flück et al., 2012). Ces critères ont vocation à définir des concentrations problématiques en contaminants, classer des échantillons de sédiments selon leur potentiel toxique, prioriser les sites à protéger/dépolluer. ...
Les enjeux écologiques, réglementaires et économiques imposent que des méthodologies robustes d'évaluation des risques environnementaux des sédiments contaminés soient proposées aux gestionnaires et autres parties prenantes. Il importe par ailleurs que ces méthodologies soient organisées selon une approche graduée, qui permette de hiérarchiser et proportionner les efforts mis en oeuvre pour l'évaluation, selon les risques potentiels sur les écosystèmes. Ce travail de thèse vise donc au développement d'un outil biologique pour l'évaluation du danger toxique lié à la contamination des sédiments d'eau douce, intégrables dans une démarche d'évaluation du risque. Il s'agit de mesurer la toxicité des sédiments naturels contaminés par des polluants chimiques, via la mesure des perturbations biologiques provoquées par l'exposition d'organismes au laboratoire. Ainsi une batterie de bioessais, composée de trois espèces phylogénétiquement différentes (G. fossarum arthropode crustacé ; P. antipodarum mollusque gastéropode et C. riparius arthropode insecte), a été mise en place. Le développement de la batterie s'est déroulé en deux étapes principales. La première a porté sur l'évaluation de la variabilité des traits de vie des organismes exposés à une série de sédiments de qualité acceptable, et couvrant une gamme la plus large possible de granulométrie et de quantité de matière organique. La réalisation de cette étape a permis de proposer, pour chaque espèce et chacun des traits considérés, une gamme de réponse considérée comme normale, en dehors de laquelle un effet toxique chimique du sédiment est significativement mis en évidence. La seconde étape consistait à comparer les réponses des traits de vie en conditions contaminées à la gamme de réponses en conditions pas / peu contaminées préalablement définie. Ainsi, la capacité à caractériser des sédiments contaminés a été évaluée pour chaque trait de vie de chaque organisme. Les résultats obtenus montrent que certains traits ont un potentiel de discrimination fort (ex : taux d'alimentation de G. fossarum) alors qu'il est très faible pour d'autres (ex : production d'embryons de P. antipodarum). Les traits au potentiel de discrimination "intermédiaire" sont traités au cas par cas. Ils peuvent en effet être moyennement sensibles à un ensemble de contaminants, ou présenter des sensibilités spécifiques (ex : la croissance de C. riparius n'a répondu qu'aux sédiments présentant une contamination aux pesticides). L'exploitation des résultats a permis d'aboutir à la définition de référentiels de réponse pour chaque trait de vie testé pour les trois espèces et à des recommandations d'utilisation des tests mis en place (quels espèces / traits conserver, comment les combiner, que faudrait-il faire pour perfectionner la batterie ?)
... Sediment quality guidelines (SQGs) are useful to screen sediment contamination by comparing sediment contaminant concentration with the corresponding quality guidelines (Caeiro et al., 2005), which evaluate the degree to which the sediments associated chemical status might adversely affect aquatic organisms and are designed to assist the interpretation of sediment quality (Wenning et al., 2005). Threshold effect level (TEL) refers to the concentration below which adverse biological effects are expected to occur rarely, and Probable effect level (PEL) indicates the concentration above which adverse effects are expected to occur frequently (Long and Morgan, 1990). ...
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.
... Chemistry, toxicity and bioaccumulation tests are frequently used to evaluate risks of contaminated sediments to environmental receptors (USEPA, 2005). Whereas chemistry measurements can provide quantitative information on contaminants, toxicity tests provides direct measures of biological impacts (ASTM, 2009).A combination of these approaches through comparison of chemistry data to toxicity effect-based sediment quality guidelines can be used to evaluate the severity of sediment contamination (Wenning et al., 2005). The ERL for Cr, Cu, Pb, and Zn in the scheme proposed by MacDonald et al. (2000) are 80, 70, 35, and 120µg/g whereas ERM for Cr, Cu, Pb, and Zn are 145, 390, 110, and 270µg/g. ...
Sediment core samples from seven stations in three Kenyan estuaries were analysed for Al, Ni, Zn, Cu, Cr, Mn and Pb by atomic absorption spectrophotometry to determine the spatial contamination (vertical and horizontal) and to identify any potential ecological risks. Samples were analysed for total metal concentration and data normalised using regression model of metal/Ni. The data was further compared to toxicity based Sediments Quality Guidelines (SQG) [Effects Range Low (ERL) and Effect Range Median (ERM)] giving an indication of potential ecological risks.There was a general reduction in metals input into the Kenya estuaries as evident from depletion of a number of metals in surface samples as compared to the subsurface samples. Enrichment Factors (EF) ranged from 0.1-92.9 indicating low to extreme contamination. Low contribution of anthropogenic sources of metal and the existence of metals in acceptable risk levels in most of the sites was also observed. However, some sites had a few samples with moderate to significant anthropogenic contribution of metals with the associated moderate to significant potential risk to biota. This study recommends a site-specific evaluation of these sites in order to quantify the level of risk, identifysource of contamination and suggest relevant management and mitigation measures.
... Traditional approaches for assessment of contaminated sediments and verification of remedial measures generally rely on laboratory-based exposures for toxicity and bioaccumulation coupled with bulk sediment chemical characterization and benthic community structure characterization [21]. While these laboratory methods provide a high degree of experimental control, often times this comes with a significant loss of representativeness due to excessive manipulation and loss of the natural conditions and integrity of the samples and exposures [22]. ...
... The routine analysis of these compounds in monitoring programs together with ecotoxicological and ecological indicators has helped the process of developing and validating SQGs around the world for many of these substances. Over the past few decades, SQGs have been developed for Btraditional^sediment contaminants including PCBs, PAHs, and organochlorine pesticides (Wenning et al. 2005;de Deckere et al. 2011). Lindane, endosulfan, and heptachlor, all of them phased out organochlorine insecticides, appear most often at concentrations below SQGs and may be recommended for reduced routine monitoring in the absence of other evidence (category 5). ...
In Switzerland, surface waters are protected by the Swiss Water Protection Ordinance (OEaux; OFEV 1998), which stipulates that the water quality shall be such that the water, suspended matter, and sediments contain no persistent synthetic substances to ensure the protection of aquatic life. Local agencies are in charge of water quality monitoring, using a set of validated methods. Several lists of priority substances have been developed for aquatic microcontaminants for surface water monitoring but not for sediments. Some local agencies have established sediment monitoring programs, but to date, there exists no harmonized methodology for sediment quality assessment in Switzerland. Within the main goal of developing and providing methodologies for monitoring sediment quality in Switzerland, a screening was performed to help prioritize sediment-relevant microcontaminants. The screening approach was largely based on the NORMAN (network of reference laboratories, research centers, and related organizations for monitoring emerging environmental substances) system and was carried out in four steps: (1) identification of candidate substances, (2) selection of sediment relevant substances, (3) classification of substances into different categories based on identified data gaps and envisaged actions, and (4) ranking within each action category. This paper describes the methodology used in the prioritization process for sediment-relevant substances and provides recommendations for monitoring strategies in Switzerland.
... The derivation of guideline values for sediments is a more recent problem, but nonetheless one that is in need of harmonization. International approaches all predominantly rely on effects data or, in some instances, mechanistic guidelines based on equilibrium partitioning (Batley et al. 2005). The values derived by various jurisdictions are quite variable (Buchman 2008), although an analysis of the causes of this variation has not been conducted. ...
... Sediment quality guidelines (SQGs) are tools which use a variety of methods and assumptions related to concentrations of contaminants in sediments to predict the intensity of biological effects (MacDonald et al. 2000;Wenning 2005). In this study, concentrations of eight heavy metals in sediments from the East Dongting Lake and Honghu Lake were evaluated in the screening levels of ecological risk based on two sets of SQGs for freshwater ecosystems: The effect range low (ERL), effect range median (ERM), the threshold effect concentration (TEC), and probable effect concentration (PEC) values were applied. ...
Eight heavy metals including Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb were investigated in surface water and sediments from a river-connected and a river-disconnected lakes (East Dongting Lake and the Honghu Lake, respectively). Zn had the highest mean concentrations in surface water in both lakes. Pearson’s correlation, principal component analysis, and hierarchical cluster analysis revealed that the distributions of Zn, Pb, and As in the East Dongting Lake and Zn, Cd, and As in the Honghu Lake were associated with anthropogenic activities. Nickel and Cr were associated with natural sources, while Cu and Hg originated from both anthropogenic and natural sources. Sediment quality guidelines revealed that both As and Hg could probably have adverse effects in the East Dongting Lake, whereas all detected heavy metals probably could not lead to adverse effects in the Honghu Lake. Potential ecological risks indices (RIs) of heavy metals in two lakes were 999.4 and 151.45, respectively, indicating greater pollution of heavy metals with high risk in the East Dongting Lake as compared to the Honghu Lake with low to moderate risk.
... Thus, responses observed in the laboratory may not occur or be as pronounced in natural systems. Higher weighting for biological LOE based on field observations is consistent with higher weighting of field-based effect studies than laboratory and chemistry-based analyses (Chapman and Anderson 2005; Wenning et al. 2005 ...
Weight of evidence (WOE) frameworks integrate environmental assessment data to reach conclusions regarding relative certainty of adverse environmental effects due to stressors, possible causation, and key uncertainties. Such studies can be investigative (i.e., determining whether adverse impact is occurring to identify a need for management) or retrospective (i.e., determining the cause of a detected impact such that management efforts focus on the correct stressor). Such WOE assessments do not themselves definitively establish causation; they provide the basis for subsequent follow-up studies to further investigate causation. We propose a modified investigative WOE framework that includes an additional weighting step, which we term “direction weighting.” This additional step allows for the examination of alternative hypotheses and provides improved certainty regarding possible causation. To our knowledge, this approach has not been previously applied in investigative ecological WOE assessments. We provide a generic example of 2 conflicting hypotheses related to a mine discharging treated effluent to a freshwater lake: chemical toxicity versus nutrient enrichment. Integr Environ Assess Manag 2017;13:702–713. © 2016 SETAC
Key Points
A novel weight of evidence (WOE) approach has been developed for investigative ecological assessment with an example conceptual model involving a northern lake receiving treated effluent from a mine. Through the application of novel “direction weighting,” the WOE approach can provide a high level of discrimination between 2 competing hypotheses: toxicity due to metals and other substances, or nutrient enrichment. This WOE approach is broadly applicable to other investigative ecological assessment situations in which both nutrient enrichment and toxicological impairment are possible. The approach can also be used to assist in resolving other competing hypotheses.
... The x-axis and y-axis stand for decimal longitude and latitude, respectively. and consequently the PAH bioavailability, into account in the sediment matrices, PAH concentrations were normalized to 1% of TOC (Burgess et al., 2000;Wenning, 2005). PAH isomeric ratios (or diagnostic ratios), Phenanthrene/Anthracene (P/A) and Fluoranthene/Pyrene (F/P) were calculated in order to determine the bulk origin of the PAH contamination in sediment samples. ...
Benthic microorganisms are key players in the recycling of organic matter and recalcitrant compounds such as polyaromatic hydrocarbons (PAHs) in coastal sediments. Despite their ecological importance, the response of microbial communities to chronic PAH pollution, one of the major threats to coastal ecosystems, has received very little attention. In one of the largest surveys performed so far on coastal sediments,
the diversity and composition of microbial communities inhabiting both chronically contaminated and non-contaminated coastal sediments were investigated using highthroughput sequencing on the 18S and 16S rRNA genes. Prokaryotic alpha-diversity showed significant association with salinity, temperature, and organic carbon content. The effect of particle size distribution was strong on eukaryotic diversity. Similarly to alpha-diversity, beta-diversity patterns were strongly influenced by the environmental filter, while PAHs had no influence on the prokaryotic community structure and a weak impact on the eukaryotic community structure at the continental scale. However, at the regional scale, PAHs became the main driver shaping the structure of bacterial and eukaryotic communities. These patterns were not found for PICRUSt predicted prokaryotic functions, thus indicating some degree of functional redundancy. Eukaryotes presented a greater potential for their use as PAH contamination biomarkers, owing to their stronger response at both regional and continental scales.
... Sediment samples for this study were collected from Hecklinger pond at the headwaters of Duck Creek, a fourmile stream that flows directly into the Maumee River and then into Lake Erie (Fig. 1). The pond has a surface area of approximately 3.32 ha with a steep concentration gradient of PCBs and PAHs as well as various heavy metal contaminants within its sediments, exceeding both the Ecological Reference and/or Human Health Reference Limits [30,31] [32,33] shortly before sample collection occurred. PCB Aroclors 1254 and 1260 in polluted sediments were detected at a concentration of 0.195 and 0.145 mg kg −1 of sediments, respectively, whereas total PCBs from the unpolluted location were undetectable. ...
Biphenyl dioxygenases, encoded by the bphA gene, initiate the oxidation of polychlorinated biphenyls (PCBs) and specify the substrate range of PCB congeners metabolized by bacteria. Increased bphA gene diversity within microbial communities may allow a broader range of PCB congeners to be catabolized, thus resulting in greater PCB degradation. To assess the role of PCBs in modulating bphA gene diversity, 16S ribosomal RNA (rRNA) gene and bphA environmental DNA libraries were generated from bacterial communities in sediments with a steep gradient of PCB contamination. Multiple measures of sequence diversity revealed greater heterogeneity of bphA sequences in polluted compared to unpolluted locations. Codon-based signatures of selection in bphA sequences provided evidence of purifying selection. Unifrac analysis of 16S rRNA sequences revealed independent taxonomic lineages from polluted and unpolluted locations, consistent with the presence of locally adapted bacterial communities. Phylogenetic analysis of bphA sequences indicated that dioxygenases from sediments were closely related to previously characterized dioxygenases that metabolize PCBs and polynuclear aromatic hydrocarbons (PAHs), consistent with high levels of these contaminants within the studied sediments. Structural analyses indicated that the BphA protein of Rhodococcus jostii, capable of metabolizing both PCBs and PAHs, provided a more optimal modeling template for bphA sequences reported in this study than a BphA homologue with more restricted substrate specificity. Results from this study suggest that PCBs and PAHs may drive local adaptation of microbial communities by acting as strong selective agents for biphenyl dioxygenases capable of metabolizing a wide range of congeners.
Thirteen elements were measured in 76 surface grab sediment samples and 90 segments of four cores from Lakes Erie and Ontario. By combining the data obtained previously from Lakes Superior, Michigan, and Huron, the spatial distribution, temporal trends, major influencing factors, anthropogenic enrichments, categorization, and ecological risks of target metals in sediment were evaluated for the Great Lakes region. Regionwide, Lake Ontario had the highest median concentrations for Ag, As, Cd, Zn, and Pb, while the highest Cr concentrations were found in the Western Basin of Lake Erie. Within Lake Ontario, Ag concentration tended to be higher towards the east. Temporal trends of the net fluxes were described by pseudo first order kinetics for selected metals in Lake Ontario. It may take more than a hundred years for the surface fluxes to decrease to the background level. The highest enrichment factor was found in Lake Ontario for Ag; while for Pb, Lake Michigan was more enriched than the other lakes. Pearson correlation, principal component, and hierarchical clustering analyses were applied to the concentration data, and, for the first time, to the estimated enrichment factor to gain insight to the human impact. Results of risk quotient analysis showed high environmental risks in most cases. Overall, the highest risk was found for Lake Ontario, followed by Lakes Erie, Superior, Huron, and Michigan. The risk quotient was strongly correlated with the enrichment factor, implying that human activities could have unfavorably affected benthic biota in the sediment of the Great Lakes.
This investigation aimed to evaluate the severity of heavy metal concentrations in suspended sediments along a 225 km section of the Ganges River in the eastern part of Uttar Pradesh, India. Metal concentrations were measured via Atomic Absorption Spectrometry, with averages recorded as Fe (50230 µg/g), Mn (1283 µg/g), Cr (201 µg/g), Zn (183 µg/g), Pb (55.1 µg/g), Ni (50.9 µg/g), Cu (42.8 µg/g), and Cd (1.01 µg/g). Zn, Fe, Cr and Pb showed anthropogenic contribution at all selected locations, while anthropogenic inputs of Mn and Ni were also observed at few locations. Risk evaluation was conducted using various pollution indicators. The Contamination Factor (CF) revealed moderate contamination (CF between 1 and 3) by Cr. The Geoaccumulation Index (GI) indicated a stage of uncontaminated to moderate contamination (GI between 0 and 1) for Cr at upstream locations. The values of Enrichment Ratios (ER) indicated minor enrichment (ER between 1 and 3) of Cr at all locations. The Pollution Load Index values ranged from 0.72 to 0.86, suggesting that the selected section is overall uncontaminated. The study highlights significant but localized anthropogenic impacts on heavy metal concentrations, particularly for chromium. While the overall assessment suggests that the suspended sediment in the studied stretch are not heavily contaminated, the elevated concentrations of iron, manganese, chromium, and nickel pose significant ecological risks. The study underscores the need for targeted pollution control measures, especially for metals with high anthropogenic contributions, to ensure the long-term health and safety of this vital water resource.
In this study, suspended solids samples were collected from 10 locations along the 225 km stream of Ganga River amidst Kanpur and Prayagraj city during July 2021 to assess heavy metal contamination. The average values of studied metal concentrations were found in the following order: Fe (51939 µg/g) > Mn (1048 µg/g) > Cr (129 µg/g) > Zn (215 µg/g) > Ni (69.5 µg/g) > Pb (71.8 µg/g) > Cu (68.9 µg/g) > Cd (1.70 µg/g). Risk Analysis was done using pollution indicators. Contamination factor average values lie between 0.62 and 1.17 indicating moderate contamination by Zn, Pb and Cd and less contamination by other metals. Geoaccumulation Index (Igeo) values indicate moderate contamination by Cu and Cr metal (Igeo > 0) at some sites. The average value of enrichment factors (EF) lies between 0.71 and 1.35 indicating no enrichment of Mn and minor enrichment of other metals. Pollution Load Index (PLI) lies between 0.69 and 1.30 indicating progressive deterioration at some sites. Nawabganj and Manikpur sites were plotted out as the most contaminated sites. Anthropogenic content and Lithogenic contribution were determined which identified anthropogenic input of Zn, Pb and Ni at all sites. Statistical analysis was done using a correlation matrix and Principal Component Analysis (PCA) which showed a strong correlation of Cu with Zn and Ni. Observed heavy metal concentrations were compared with averages of other world rivers. The increased levels of Zn, Cd, and Pb may have resulted from the tannery and paint industries of the upstream Jajmau industrial area and also because of excessive use of pesticides and fertilizers which should be taken seriously to prevent further increase in heavy metals concentrations.
Sediments absorb and accumulate toxic elements, which might be re-activated and easily released into the water body, which could be a serious ecological risk to the aquatic ecosystem. It is a vital environmental medium widely used for characterizing anthropogenic contaminants. This study assessed the extent of pollution and the ecological threat posed by potentially toxic elements in the bottom sediment of a stream in Oke-Ere, Kogi State, North Central Nigeria. A total of 72 samples were collected and analyzed with inductively coupled plasma mass spectroscopy (ICP-MS), after acid digestion. The data obtained were subjected to simple descriptive and inferential statistics. Sediment pollution levels and ecological risk were evaluated based on models of sediment quality guidelines (SQGs), geo-accumulation index (Igeo), enrichment factor (EF), pollution load index (PLI), contamination factor (Cf), and potential ecological risk (Eir). Based on SQGs, average levels of Zn, Pb, Cr, and Cu exceeded the threshold effect concentrations (TEC), but no collective toxicity from the studied elements as the value of mPEC-Q was < 0.5. The pollution indices studies (Igeo, EF, PLI, and Cf) revealed that the bottom sediment samples were low to moderate contaminated with the investigated elements and ecological risk revealed that the bottom sediment samples were within the low to moderate class, and Mo contributed 56% of the total potential ecological risk. However, appropriate measures should be taken to avoid serious ecological risks to the study area.
Graphical abstract
Environmental context This special issue is a tribute to Graeme Batley’s career and his many contributions to the field of environmental chemistry.
This study analyses the heavy metal contamination in freshly deposited sediment of 210 km stretch of River Ganga between Kanpur and Prayagraj, Uttar Pradesh (U.P.), India. As per APHA (2012)30 digested samples were prepared after collecting from 10 sampling sites. Then the samples were analyzed for 8 heavy metals namely Cadmium (Cd), Chromium (Cr), Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb), and Zinc (Zn) by Atomic Absorption Spectroscopy (AAS) (Shimadzu AA-6300). Risk assessment was done by employing four pollution indices. The average values of contamination factor (CF) indicate that the level of contamination by Pb is moderate (1 < CF < 3) and significant by Cd (3 < CF < 6). Whereas, the average value of Geo-accumulation index (Igeo) indicates that the sediments are uncontaminated or in a moderate level of contamination by Pb (0 < Igeo < 1) and in a moderate level of contamination by Cd (1 < Igeo < 2), which may have harmful effects on Ganga River ecology. The values of Pollution load index (PLI) indicate that the Ganga River sediment has a low level of contamination. Based on various pollution indicators, it has been observed that concentrations of Cd and Pb in the river sediment is a matter of concern and may lead to further deterioration of sediment quality in near future due to increasing anthropogenic activities in the river basin, hence proper management strategies should be taken to control the direct dumping of both domestic and industrial wastewater in the river.
The review was conducted by an Independent Technical Review Team (ITRT) composed of seven individuals (scientists and engineers) from across the country and the region. This expert panel had extensive experience in fields including: sediment biogeochemistry, metal and organic contaminants, toxicology, risk assessment, human health issues, dredging operations, and sediment management.
Investigation of heavy metals in the bed sediments of wetlands can be used as an appropriate index for determining environmental quality of wetlands. In this study, the concentration of lead (Pb), zinc (Zn) and cadmium (Cd) in sediments of 8 points in the Hashilan wetland was evaluated. Geo-accumulation index (Igeo), input potential index (IPI) and pollution index (PI) calculated for bed sediments of the wetland. The Igeo for Cd, Pb and Zn were obtained as −2.29 to −2.68, −0.86 to −1.15 and −1.77 to −2.12. The PIs for mentioned heavy metals were 0.1–0.3, 0.07–0.14 and 0.007–0.01; and the IPI were 0.19, 0.1 and 0.009, respectively. Based on the results, the concentration of heavy metals in this wetland is lower than international standards, and this wetland is classified as clean and pollution-free regions.
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 (Eri), 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 84.24 mg/kg dry wt, respectively. Both I-geo and Eri 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 Eri are low as their average concentrations is below Hebei province pre-contaminations (30.8 mg/kg for Ni and 68.3 mg/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 12.22 g/person/day fish muscle for the entire life is safe from noncarcinogenic human health problems.
Trace elements contamination in sediment is regarded as the global crisis with a large share in developing countries like China. Water and sediment samples were collected during (2016) from Qingshui Stream and analyzed for major physicochemical properties and trace elements by using ICP-MS. Our result of sediments showed that studied trace elements (except Pb, Cd, Co) had a concentration higher than Chinese sediment guideline as well as stream water data for studied trace elements (except Cr, Pb, Cd, Cu, and Zn) had a higher concentration than the maximum permissible safe limit of WHO. Contamination factor (CF) confirmed a moderate to high contamination in the sediment samples due to As and Tl, respectively. The values of pollution load index (PLI) were found above one (> 1), describing the progressive sediment quality decline. Pearson correlation showed that there was a significant positive association between Tl and As (r = 0.725, p < 0.05) in sediment samples. Results revealed that water-rock interaction, weathering of Tl sulfide mineralization, and hydrogeological conditions were major sources of stream water and sediments contamination in the study area. This experimental study contributes to a better understanding of the geochemistry and prevention of trace element contamination in sediments from Lanmuchang area.
This report describes the results of the investigation of soil and water quality including heavy metal pollution in the vicinity of the Cerrejón coal mine in Colombia. This work was carried out in cooperation with the NGO Indepaz.
A series of acute toxicity studies exposed G. bonnieroides to different sediment particles (SP), materials used in whole sediment toxicity identification evaluations (TIE), and environmental samples (ES). The results from different experimental steps have confirmed that no significant difference was found between treatments (SP and TIE) and their control samples, thus indicating that the species can be successfully used in this type of experiment. Due to the high survival percentage (97.5% average) observed in all test replicates, the species characteristics that enable it to be used as a standardized species, with high ecological representativeness in tropical ecosystem toxicity tests were discussed. Finally, environmental sample analyses were performed to validate the procedures and confirm the tested amphipod viability and suitability.
https://www.dal.ca/content/dam/dalhousie/pdf/faculty/science/marine-affairs-program/Technical_series/MAPTechnicalReport15.pdf
The potential performance (i.e., ability to separate nontoxic from toxic sediments) of a range of international Disposal at Sea (DaS) chemical Action Levels (ALs) was compared using a sediment chemical and toxicological database. The use of chemistry alone (without the use of further lines of evidence) did not perform well at reducing costs and protecting the environment. Although some approaches for interpreting AL1 results are very effective at filtering out the majority of acutely toxic sediments, without subsequent toxicological assessment, a large proportion of nontoxic sediments would be unnecessarily subjected to treatment and containment, and a number of sublethally toxic sediments would be missed. Even the best tiered systems that collect and evaluate information sequentially resulted in the failure to catch at least some sublethally or acutely toxic sediments. None of the AL2s examined were particularly effective in distinguishing between non-, sublethally, or acutely toxic sediments. Thus, this review did not support the use of chemical AL2s to predict the degree to which sediments will be toxic. Integr Environ Assess Manag 2017;13:1086–1099.© 2017 The Authors. Integrated Environmental Assessment and Management Published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Key Points
Chemistry alone performs poorly at reducing costs and protecting the environment. Some chemical Action Level (AL) 1 strategies filter out the majority of toxic sediments, but with high false positives. Many tiered systems were able to discriminate most toxic and nontoxic sediments. None of the AL2s examined were effective in distinguishing between nontoxic and toxic sediments.
Sediments are an essential component of fluvial ecosystems. They are also quite often a cause of disturbance for fluvial works, such as dams or locks. In order to manage these disturbances without causing adverse impacts downstream, managers should have in hand an efficient assessment framework. The DIESE project (tools for sediment ecotoxicity assessment) aimed to elaborate and test a tiered assessment framework for freshwater sediment sites. We present hereafter the proposed framework, and a pilot test on 17 sites. Basically, the framework intends to provide answers to 2 questions, namely (a) does the sediment contamination present a hazard to benthic invertebrates, and (b) if bioaccumulative/biomagnified contaminants are present, is their concentration worrying? The assessment process can end at any tier, provided the data are conclusive. Sediment quality benchmarks or contamination indices were used to interpret chemical analyses; this assessment was then compared to the results of ecotoxicity tests. Overall, the framework appears consistent; this test also helped selecting the best options for interpretation. Nevertheless, the test included only 17 sites, with a limited array of contaminants; complementary tests including more organic contaminants at a wider range of concentrations would help to demonstrate the validity of this assessment framework.
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