Field and laboratory evaluation of DGT for predicting metal bioaccumulation and toxicity in the freshwater bivalve Hyridella australis exposed to contaminated sediments

Abstract

The diffusive gradients in thin films (DGT) technique has shown to be a useful tool for predicting metal bioavailability and toxicity in sediments, however, links between DGT measurements and biological responses have often relied on laboratory-based exposures and further field evaluations are required. In this study, DGT probes were deployed in metal-contaminated (Cd, Pb, Zn) sediments to evaluate relationships between bioaccumulation by the freshwater bivalve Hyridella australis and DGT-metal fluxes under both laboratory and field conditions. The DGT-metal flux measured across the sediment/water interface (±1 cm) was useful for predicting significant cadmium and zinc bioaccumulation, irrespective of the type of sediment and exposure. A greater DGT-Zn flux measured in the field was consistent with significantly higher zinc bioaccumulation, highlighting the importance of performing metal bioavailability assessments in situ. In addition, DGT fluxes were useful for predicting the potential risk of sub-lethal toxicity (i.e., lipid peroxidation and lysosomal membrane damage). Due to its ability to account for multiple metal exposures, DGT better predicted bioaccumulation and toxicity than particulate metal concentrations in sediments. These results provide further evidence supporting the applicability of the DGT technique as a monitoring tool for sediment quality assessment.

Effects of Dissolved Organic Carbon on Copper Toxicity to Embryos of Mytilus galloprovincialis as Measured by Diffusive Gradient in Thin Films

“…Although the efficacy of DGT for in situ passive sampling of metals in natural systems has been demonstrated (e.g., Dunn et al 2003;Warnken et al 2004;Amato et al 2018), an increased understanding of the relationship between the concentration in solution as measured by DGT (C DGT ) and toxicity/ bioaccumulation measurements is necessary for implementation of DGTs in surface water monitoring programs. The appropriate choice for application to seawater monitoring is the relation of C DGT to embryo-larval development tests using the Mediterranean mussel, M. galloprovincialis, which is among the most sensitive saltwater bioassay endpoints used for aquatic life criteria development (US Environmental Protection Agency 1995b, 2016Arnold et al 2005;Rosen et al 2005).…”

Assessing the Risk of Metals and Their Mixtures in the Antarctic Nearshore Marine Environment with Diffusive Gradients in Thin-Films

“…Previous assessments have found that contaminants are also deposited to the benthic environment via sedimentation 8,60 . DGT samplers have been used in temperate and tropical sediments to assess the bioavailable metal flux from sediments to overlying waters, which has shown good agreement with toxicity and bioaccumulation to benthic organisms [17][18][19]61 . While the metal concentrations in Antarctic sediments and benthic organisms are commonly reported 60,[62][63][64][65][66] , the DGT technique combined with sediment-based ecological or toxicology assessments may also provide a way to translate the presence of a contaminant to its risk to the benthic ecosystem.…”

“…Diffusive gradients in thin-films (DGT) is an in situ passive sampling technique that has been used in Antarctica to assess labile metal concentrations in marine waters. ,− While DGT is predominately used to measure a labile fraction of metal contaminants in the environment, it has recently been used to predict the toxicity and bioavailability of contaminants to benthic organisms. − The ease of use, ability to provide a time-averaged measure of a labile metal fraction, low cost, and simultaneous detection of multiple contaminants makes DGT samplers an attractive option for environmental monitoring, especially in remote and harsh environments. However, their application to the Antarctic marine environment and practicality to environmental managers is still unclear …”

In Situ DGT Sensing of Bioavailable Metal Fluxes to Improve Toxicity Predictions for Sediments

“…The diffusive gradients in thin films (DGT) technique has become popular for determining concentrations of labile metals within sediments. , When deployed in sediments, the DGT device accumulates metals present in the porewater including the weakly bound metals released from sediment particles by diffusion, and provides a measure of the time-integrated labile metal fluxes . Through measurement of a combined pool of labile metals, this technique has been applied for the purpose of assessing the metal exchange at the sediment water interface − (whether sediments are acting as a sink or source), potentially bioavailable concentrations, − as well as the risk of toxicity to benthic organisms exposed to metal-contaminated sediments. − Multiple studies have observed that increasing concentrations of DGT-labile metals correlate with increasing bioaccumulation, − and that toxic effects thresholds based on DGT-induced metal flux measurements provide better predictions of risk than total sediment metal concentrations ,, or other solid-phase extraction measures …”