Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata

Abstract

A laboratory bioassay determined the relative contribution of various pathways of Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata exposed to moderately contaminated sediments. Juvenile worms were exposed for 25 d to experimental sediments containing 5 different reactive sulfide (acid volatile sulfides, AVS) concentrations (1 to 30 µmol g , respectively. The sediments were supplemented with contaminated food (TetraMin ® ) containing 3 levels of Ag-Cd-Zn (uncontaminated, 1 × or 5 × metal concentrations in the contaminated sediment). The results suggest that bioaccumulation of Ag, Cd and Zn in the worms occurred predominantly from ingestion of contaminated sediments and contaminated supplementary food. AVS or dissolved metals (in porewater and overlying water) had a minor effect on bioaccumulation of the 3 metals in most of the treatments. The contribution to uptake from the dissolved source was most important in the most oxic sediments, with maximum contributions of 8% for Ag, 30% for Cd and 20% for Zn bioaccumulation. Sediment bioassays where uncontaminated supplemental food is added could seriously underestimate metal exposures in an equilibrated system; N. arenaceodentata feeding on uncontaminated food would be exposed to 40-60% less metal than if the food source was equilibrated (as occurs in nature). Overall, the results show that pathways of metal exposure are dynamically linked in contaminated sediments and shift as external geochemical characteristics and internal biological attributes vary. KEY WORDS: Bioaccumulation · Metals · AVS · Dietary uptakeResale or republication not permitted without written consent of the publisher

Peer Reviewed: Chemical Dynamics of Sedimentary Acid Volatile Sulfide

“…The graded shading of the pyrite (FeS 2 ) and FeS stability fields indicate relative supersaturation; the darker color indicates higher supersaturation. In suboxic systems, which are situated near the SO 4 2-/S(-II) boundary, small changes in redox conditions (represented by the standard potential relative to the hydrogen half-cell, Eh) result in major changes in pyrite supersaturation. This means that the rate of formation of pyrite is extremely sensitive to the local physicochemical conditions.…”

“…Uncomplexed aqueous S(-II) is highly toxic to most organisms and even sulfate-reducing bacteria, which produce almost all sedimentary S(-II) and have a limited free S(-II) tolerance. More recent toxicological studies have raised serious questions about the general applicability of the earlier work (3,4). In other words, toxicity is not only a function of the metal concentrations; the toxic effects of metals and S(-II) need to be deconvoluted as well.…”

Sediment Ecosystem Assessment Protocol (SEAP): An Accurate and Integrated Weight-of-Evidence Based System

“…arenaceodentata and related Nereid polychaetes have been used extensively in North America for acute and chronic toxicity (Johns et al 1990, Emery and Dillon 1996, ASTM 2000 and bioaccumulation testing (Lee et al, 2001), and they continue to be the subject of novel test development. Several summaries exist that focus either exclusively on the use of N. arenaceodentata as a test organism or reference them heavily (Reish et al, 1976;Reish and Gerlinger, 1984;Johns et al, 1990, Reish andGerlinger 1997).…”

Measurement of Acid Volatile Sulphide and Simultaneously Extracted Metals in Sediment from Lake Albufera (Valencia, Spain)

“…Lee et al (2001Lee et al ( , 2004) examined the toxicity of trace 64 metals to benthic organisms under more natural conditions than used in earlier bioassays by 65 employing more moderate metal concentrations and longer exposure times. They reported that 66 marine polychaetes accumulated metals predominately via the ingestion of contaminated 67 sediments and that dissolved metals in pore water had a minor influence on metal 68 bioaccumulation.…”