Efficiency of sediment quality guidelines to predict toxicity: The case of the St. Lawrence River

Cemagref UR MALY, 3bis quai Chauveau CP 220, 69336 Lyon Cedex 9, France.
Integrated Environmental Assessment and Management (Impact Factor: 1.38). 04/2010; 6(2):225-39. DOI: 10.1897/IEAM_2009-026.1
Source: PubMed


Multitiered frameworks that are designed for risk assessment of contaminated sediment rely on sediment quality guidelines (SQGs) at the first tier or screening level. In the case of contamination by multiple pollutants, results can be aggregated under indices such as the mean quotient. A decision is then reached (e.g., to dispose of dredged materials in open water) without further investigation, provided that the SQGs or the specific values of indices or quotients derived from the SQGs are not exceeded. In this way, SQGs and quotients play a critical role in environmental protection. As part of the development of a tiered framework to assess the environmental risk of materials dredged from the St. Lawrence River, we evaluated various quotients based on SQGs available for this river with a data set that matches chemistry and toxicity test endpoints. The overall efficiency of all tested quotients was rather low, and we then examined factors such as sediment grain size, nutrients, metal-binding phases (e.g., Al, Fe), and dissolved organic carbon to explain misclassified samples. This examination led to the design of a modified tier 1 framework in which SQGs are used in combination with decision rules based on certain explanatory factors.

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    • "The underlying idea is to compute an index score for each sample, which takes into account the number of variables (here the metals) that exceed guideline values, as well as the magnitude of excess for each variable. Several countries have developed their own sediment guideline values (MacDonald et al., 2000; Desrosiers et al., 2010). However, there is a lack of clear directives in France, and even in the European Union (Besten et al., 2003). "
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    ABSTRACT: This study seeks to determine to what extent trace metals resulting from past mining activities are transferred to the aquatic ecosystem, and whether such trace metals still exert deleterious effects on biota. Concentrations of Cd, Cu, Pb and Zn were measured in streambed sediments, transplanted bryophytes and wild brown trout. This study was conducted at two scales: (i) the entire Morvan Regional Nature Park and (ii) three small watersheds selected for their degree of contamination, based on the presence or absence of past mining sites. The overall quality of streambed sediments was assessed using Sediment Quality Indices (SQIs). According to these standard guidelines, more than 96% of the sediments sampled should not represent a threat to biota. Nonetheless, in watersheds where past mining occurred, SQIs are significantly lower. Transplanted bryophytes at these sites consistently present higher trace metal concentrations. For wild brown trout, the scaled mass and liver indices appear to be negatively correlated with liver Pb concentrations, but there are no obvious relationships between past mining and liver metal concentrations or the developmental instability of specimens. Although the impact of past mining and metallurgical works is apparently not as strong as that usually observed in modern mining sites, it is still traceable. For this reason, past mining sites should be monitored, particularly in protected areas erroneously thought to be free of anthropogenic contamination.
    Full-text · Article · Sep 2014 · Environmental Research
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    • "Comprehensive chemical monitoring is required in regions with multiple sources of contaminants as it is necessary for the identification of high-risk sites for further assessment. Many authors deal with the classification of sediments according to HM contamination (e.g., MacDonald et al. 2000; Burton 2002; Chapman 2007; Desrosiers et al. 2010; Milacic et al. 2010). In this study, concentrations of HMs were normalized and compared with background levels to distinguish whether there was contamination caused by anthropogenic activities or whether the HMs occurred naturally. "
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    ABSTRACT: Purpose The main purpose of this study was to evaluate temporal and regional variability of contamination by heavy metals (HMs) in river sediments using their enrichment factors (EFs) and benchmarking according to sediment quality guidelines (SQGs). The Zlin region in the Czech Republic (Morava and Drevnice River basins) represents a model area where several regionally specific ecological risk assessment studies have recently been conducted with a focus on organic pollution, eco-toxicity, geological, and geochemical characteristics. Materials and methods Four consecutive sediment sampling campaigns were undertaken in spring and autumn 2005–2006. Aqua-regia leachable content of Cd, Co, Cr, Cu, Ni, Pb, Sb, V, and Zn in surface sediments from 14 sites was analyzed using ICP-MS, and Hg content was analyzed using AMA-254 analyzer. EFs were calculated to identify the human impact on pollution in the area. Comparisons to SGQs were conducted to identify the areas and HMs of greatest risk. Results and discussion Calculation of EFs contributed to the effective clustering of HMs. Median EFs of Co, Ni, and V ranged from 0.9 to 1.4 at all sites indicating concentrations very close to natural geological background levels. There was greater enrichment at locally polluted sites, the highest in the cases of Cd, Sb, Hg, and Cr. Widespread influence of diffuse HM sources (traffic, agriculture, and urban wastes) was apparent from elevated concentrations of Pb, Cu, and Zn at all sites. EF values also helped to identify the greatest temporal changes and shifts in HMs contamination between adjacent sites caused by 50-year recurrence interval floods in early spring 2006. The impact was most apparent in downstream sites; namely directly below the confluence of the two major rivers. Conclusions The overall contamination of HMs in the region was classified as low-to-moderate with significantly contaminated sub-areas. The study showed relatively stable spatial distributions of HMs, indicating potential sources of pollution. Cu was identified as the HM of greatest risk. The study emphasizes the necessity of considering both environmental circumstances and background HM occurrence to prevent misinterpretation of the pollution situation. The use of EFs which include grain size proxy normalization and HM background levels, along with the comparison of the detected concentrations to SQGs, proved an efficient way to identify hazardous contamination from anthropogenic sources.
    Full-text · Article · Aug 2013 · Journal of Soils and Sediments
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    • "Therefore, the assessment of sediment environmental quality is an essential component of environmental quality assessment of aquatic ecosystems . Several risk assessment indices of sediment environmental quality for heavy metals have been developed on different bases, such as geoaccumulation index (I geo ) on the basis of total content (Loska et al., 2004; Abrahim and Parker, 2008; Lu et al., 2009), risk assessment code (RAC) on the basis of availability (Jain, 2004; Passos et al., 2010), sediment quality guidelines (SQGs) on the basis of biological toxicity (Wenning and Ingersoll, 2002; Long et al., 2005; Leung et al., 2006; Desrosiers et al., 2010), and multiple variant approach (Viguri et al., 2007). "
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    ABSTRACT: Numerous indices have been developed to assess environmental risk of heavy metals in surface sediments, including the total content based geoaccumulation index (I(geo)), exchangeable fraction based risk assessment code (RAC), and biological toxicity test based sediment quality guidelines (SQGs). In this study, the three indices were applied to freshwater surface sediments from 10 sections along an urbanization gradient of the Grand Canal, China to assess the environmental risks of heavy metals (Cu, Pb, Zn, Cd, and Cr) and to understand discrepancies of risk assessment indices and urbanization effects regarding heavy metal contamination. Results showed that Cd, Zn, and Pb were the most enriched metals in urban sections assessed by I(geo) and over 95% of the samples exceeded the Zn and Pb thresholds of the effect range low (ERL) of SQGs. According to RAC, Cu, Zn, Cd, and Cr had high risks of adversely affecting the water quality of the Grand Canal due to their remarkable portions of exchangeable fraction in surface sediment. However, Pb showed a relative low risk, and was largely bounded to Fe/Mn oxides in the urban surface sediments. Obviously, the three assessment indices were not consistent with each other in terms of predicting environmental risks attributed to heavy metals in the freshwater surface sediments of this study. It is recommended that risk assessment by SQGs should be revised according to availability and site specificity. However, the combination of the three indices gave us a comprehensive understanding of heavy metal risks in the urban surface sediments of the Grand Canal.
    Full-text · Article · Aug 2011 · Chemosphere
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