Assessment of Sedimentary Cu Availability:  A Comparison of Biomimetic and AVS Approaches

• Published in: Environmental science & technology 1999-02, Vol.33 (4), p.650-652
• Main Authors: Chen, Zhen, Mayer, Lawrence M
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Chemistry; Copper; Ecotoxicology, biological effects of pollution; Fundamental and applied biological sciences. Psychology; Sediments; Terrestrial environment, soil, air
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es980615k

Sedimentary Cu bioavailability during deposit feeding is determined by both the digestive physiology of the organisms and the geochemistry of the sediments. We assessed the contribution of these two factors by using a biomimetic approach involving extraction of Cu with digestive fluids of two deposit feeders and one suspension feeder and a geochemical approach measuring Cu associated with acid-volatile sulfide (AVS) in sediments. Cu bioavailability determined by the biomimetic method varied among species with varying digestive physiology but all showed a marked increase when SEMCu-AVS ≥ 0, corroborating the premise underlying the AVS method in determining sedimentary Cu bioavailability. The existence of a positive SEMCu-AVS threshold (0.4−1.5 μmol/g-sediment) suggests the existence of additional Cu-binding phases or mixed Cu(I)−Cu(II) sulfides in sediments. In addition, Cu bioavailable to digestive fluids was much less than that measured as SEMCu-AVS, indicating that the AVS method overestimates Cu bioavailability to digestive fluid of deposit feeders. Incubation of digestive fluids with two Cu-bound model phases, goethite and sulfide, corroborated the relative unavailability of sulfide-bound Cu. Subsurface deposit feeders feeding on anoxic sediments may be exposed to less Cu than their surface-feeding counterparts in Cu-contaminated environments.