Critical review of mercury sediment quality values for the protection of benthic invertebrates

Abstract

Sediment quality values (SQV) are commonly used-and misused-to characterize the need for investigation, understand causes of observed effects, and derive management strategies to protect benthic invertebrates from direct toxic effects. The authors compiled more than 40 SQVs for mercury, nearly all of which are "co-occurrence" SQVs derived from databases of paired chemistry and benthic invertebrate effects data obtained from field-collected sediment. Co-occurrence SQVs are not derived in a manner that reflects cause-effect, concentration-response relationships for individual chemicals such as mercury, because multiple potential stressors often co-occur in the data sets used to derive SQVs. The authors assembled alternative data to characterize mercury-specific effect thresholds, including results of 7 laboratory studies with mercury-spiked sediments and 23 studies at mercury-contaminated sites (e.g., chloralkali facilities, mercury mines). The median (AE interquartile range) co-occurrence SQVs associated with a lack of effects (0.16 mg/kg [0.13-0.20 mg/kg]) or a potential for effects (0.88 mg/kg [0.50-1.4 mg/kg]) were orders of magnitude lower than no-observed-effect concentrations reported in mercury-spiked toxicity studies (3.3 mg/kg [1.1-9.4 mg/kg]) and mercury site investigations (22 mg/kg [3.8-66 mg/kg]). Additionally, there was a high degree of overlap between co-occurrence SQVs and background mercury levels. Although SQVs are appropriate only for initial screening, they are commonly misused for characterizing or managing risks at mercury-contaminated sites. Spiked sediment and site data provide more appropriate and useful alternative information for characterization and management purposes. Further research is recommended to refine mercury effect thresholds for sediment that address the bioavailability and causal effects of mercury exposure. Environ Toxicol Chem 2015;34:6-21. # 2014 SETAC

Assessment of potential mercury toxicity to native invertebrates in a high‐gradient stream

“…The South River was impacted with Hg released from use at a textile manufacturing facility in Waynesboro, Virginia (Figure 1) between 1929 and 1950 (Carter 1977). Despite physical characteristics that would seem to limit rates of Hg methylation (coarse-grained substrates in many reaches of the river, high flow velocities, low sulfate and OC concentrations; Flanders et al 2010), concentrations of total Hg (THg) and methylmercury (MeHg) in fish and wildlife from this system remain elevated (e.g., Cristol et al 2008) despite more than 50 y of natural recovery.…”

“…The work described here is a field-level investigation of the potential effects of sediment Hg on invertebrate communities using multiple lines of evidence, which was conducted as part of a watershed-level risk assessment for the South River (Stahl et al 2014). Lines of evidence included the sediment quality triad (SQT), which integrates spatially and temporally matched sediment chemistry, invertebrate community assessments, and toxicity testing (Long and Chapman 1985;Chapman et al 1987).…”

Impact of extreme metal contamination at the supra-individual level in a contaminated bay ecosystem

“…The nation-wide Sediment Quality Standard (GB18668-2002) (CSBQTS, 2002) for Chinese seas was not used in this study because the regulatory values (Class I and II limits) were believed to be under- protective for local organisms. The TEL-PEL method has been widely used in a variety of studies (e.g., Gao and Chen, 2012;Conder et al, 2015). Despite the use of non-native species toxicity data, the toxicity predictive ability of this method was thought to be comparable to the local SQGs, thus providing sufficient protection of the local ecosystems (Jin et al, 2015).…”

Predictive Ecotoxicology and Environmental Assessment

“…However, these standards remain useful for initial screening steps or as part of a weight of evidence approach (Zhuang and Gao, 2014;Conder et al, 2015) as implemented by Benedetti et al (2012) for the classification of polluted sediments integrating sediment chemistry, bioavailability, biomarker responses, and bioassays. Dagnino and Variengo (2014) have developed an expert decision support system for the management of contamination in marine coastal ecosystems, the first step of which consists in a comparison of concentrations to effect-based thresholds (threshold effect levels and probable effect levels developed by MacDonald et al (1996)), ignoring the problem of bioavailability.…”

“…In this context, the validity of environmental quality standards is crucial: they must not be overprotective (e.g., Conder et al, 2015) or underprotective (e.g., Kattwinkel and Liess, 2014). However, uncertainty is the rule rather than the exception even for contaminants studied by these authors (mercury, pesticides) that gave rise to so many studies over decades.…”