Characterizing sediment acid volatile sulfide concentrations in European streams

Abstract

Sediment acid volatile sulfide (AVS) concentrations were measured in wadeable streams of a wide variety of ecoregions of western Europe (84 sites in 10 countries and nine ecoregions) to better understand spatial distribution and ecoregion relationships. Acid volatile sulfide has been shown to be a major factor controlling the bioavailability and toxicity of many common trace metals, such as Cd, Cu, Ni, Pb, and Zn. Sediment characteristics varied widely. The ratio of the sum of the simultaneously extracted metals (SEM) to AVS ranged from 0.03 to 486.59. The sigmaSEM-AVS ranged from -40.02 to 17.71 micromol/g. On a regional scale, sediment characteristics such as dominant parent soil material showed significant trends in AVS distribution and variation by ecoregion. Total Fe and Mn were correlated weakly with SEM concentrations. Three AVS model approaches (i.e., the SEM:AVS ratio, SEM-AVS difference, and carbon normalization) were compared at threshold exceedance levels of SEM/AVS > 9, SEM-AVS > 2, and SEM-AVS/foc > 150 micromol/g organic carbon (OC). Only 4.76% of the sediments exceeded all three AVS thresholds; 22.6% of the sediments exceeded two models; and 13% of the sediments exceeded one model only. Using the SEM:AVS, SEM-AVS, and fraction of organic carbon models, and including site-specific data and regional soil characteristics, ecoregions 1 (Portugal), 3 (Italy), 4 (Switzerland), and 9 (Belgium/Germany) had the highest potential metals toxicity; ecoregions 13 and 8 (Belgium/France) showed the lowest potential toxicity. However, because AVS can vary widely spatially and temporally, these data should not be considered as representative of the sampled ecoregions. The general relationship between AVS levels and sediment characteristics provides some predictive capability for wadeable streams in the European ecoregions.

Assessing contaminated sediments in the context of multiple stressors

“…Acid volatile sulfides are found only in anoxic, depositional sediments, which are the sediments of greatest concern because these are where chemicals accumulate. Significant focus has been directed on why the AVS to simultaneously extracted metal (SEM) relationship might not be predictive of toxicity levels in benthic organisms [36,[116][117][118][119][120][121][122][123][124][125][126][127]. For example, most burrowing animals have oxygenated burrows and would rarely interact with the sulfide-rich anoxic sediment component [128].…”

Measurements of acid volatile sulfide and simultaneously extracted metals are irreproducible among laboratories

“…These streams were selected to provide a range of AVS and SEM concentrations that are representative of deposits in other freshwater systems [20]. Bulk surface sediments (%2 L) were sampled from each stream following U.S. EPA-recommended guidelines [21], homogenized by rigorous stirring, and aliquots divided into 125-cm 3 polyethylene specimen cups that were filled completely (i.e., no head space), sealed hermetically, and frozen (< À208C).…”

Spatial distribution and toxicity assessment of heavy metals in sediments of Liaohe River, northeast China

“…Furthermore, AVS was an operationally defined parameter, affected by a variety of dynamic biochemical processes, such as deposition, oxidation or bioturbation, resulting in the AVS variation temporally and spatially (Burton et al 2007). Therefore AVS-SEM models could not lead to a definitive conclusion about the sediment toxicity.…”

“…Accordingly, Di Toro et al (1990) formulated the AVS-SEM model for evaluating sediment toxicology at the beginning of the 1990s. Since then, AVS-SEM models have been successfully used for predicting potential metal availability in laboratory and field studies (Di Toro et al 1990;Berry et al 1996) and are widely used in both marine and freshwater sediments (Burton et al 2007;Nizoli and Luiz-Silva 2012). Up to date, both SQGs and AVS-SEM methods have been extensively applied to evaluate the sediment quality (Ribeiro et al 2013;Mwanamoki et al 2014;Li et al 2014b).…”