Effects of organic amendments on the toxicity and bioavailability of cadmium and copper in spiked formulated sediments

Abstract

We evaluated the partitioning and toxicity of cadmium (Cd) and copper (Cu) spiked into formulated sediments containing two types of organic matter (OM), i.e., cellulose and humus. Amendments of cellulose up to 12.5% total organic carbon (TOC) did not affect partitioning of Cd or Cu between sediment and pore water and did not significantly affect the toxicity of spiked sediments in acute toxicity tests with the amphipod Hyalella azteca. In contrast, amendments of natural humus shifted the partitioning of hoth Cd and Cu toward greater concentrations in sediment and lesser concentrations in pore water and significantly reduced toxic effects of both metals. Thresholds for toxicity, based on measured metal concentrations in whole sediment, were greater for both Cd and Cu in sediments amended with a low level of humus (2.9% TOC) than in sediments without added OM. Amendments with a high level of humus (8.9% TOC) eliminated toxicity at the highest spike concentrations of both metals (sediment concentrations of 12.4 microg Cd/g and 493 microg Cu/g). Concentrations of Cd in pore water associated with acute toxicity were similar between sediments with and without humus amendments, suggesting that toxicity of Cd was reduced primarily by sorption to sediment OM. However, toxic effects of Cu in humus treatments were associated with greater pore-water concentrations than in controls, suggesting that toxicity of Cu was reduced both by sorption and by complexation with soluble ligands. Both sorption and complexation by OM tend to make proposed sediment quality guidelines (SQGs) based on total metal concentrations more protective for high-OM sediments. Our results suggest that the predictive ability of SQGs could be improved by models of metal interactions with natural OM in sediment and pore water.

The influence of sediment particle size and organic carbon on toxicity of copper to benthic invertebrates in oxic/suboxic surface sediments

“…These results reconfirmed OC as a major Cu-binding phase [3,4,11,43] and that the prediction of Cu bioavailability in sediments is significantly improved by normalizing particulate Cu concentrations to the concentrations of OC. The results were also consistent with the study by Costa et al [30], which reported 10-d LC50 values for the amphipod Gammarus locusta of 6.8, 57, and >200 mg Cu/kg for sediments with increasing amounts of silt and organic matter.…”

“…30,2011and sulfide phases being oxidized at the sediment-water interface (SWI) [27]. Copper forms strong complexes with naturally occurring organic ligands, and the bioavailability and toxicity of dissolved Cu was expected to decrease with increasing DOC concentrations [4,11]. The DOC concentrations in the overlying waters were less than 1 mg/L in all tests.…”

“…The toxicity of metal contaminants in sediments to benthic organisms is influenced by the chemistry and speciation of the metal, the properties of the sediments, and the varying exposure pathways of different organisms [4][5][6]. The exposure and bioavailability of metals from both the dissolved phase (through exposure to pore water, burrow water, or overlying water) and sediment phases (through ingestion of particles) and the sensitivity of the organism to these metal exposures all need to be understood to predict effects [7][8][9][10].…”

Short-term accumulation of Cd and Cu from water, sediment and algae by the amphipod Melita plumulosa and the bivalve Tellina deltoidalis

“…It is well recognised that partitioning between sediments and pore waters is greatly affected by sediment properties (Besser et al 2003, Simpson et al 2004. In estuarine/marine environments, cadmium exhibits a greater solubility than copper due to strong complexation by chloride, and for oxic surface sediments, Kd values are typically within an order of magnitude of 10 3 l kg -1 for cadmium and 10 4 to 10 5 l kg -1 for copper (Stumm & Morgan 1996).…”

Quantifying Bioavailability and Toxicity of Copper to Americamysis bahia - Mysid Shrimp

“…Organic chelators, such as EDTA and dissolved organic matter, complex cupric ions to generally decrease toxicity [17]- [23], although increased toxicity is sometimes observed [24]. In seawater, organic matter content varies between 0.3 and 5 mg/L of carbon; about 90% of the dissolved copper is sorbed to this NOM [25].…”