In Vitro Zn-Nitzschia closterium Interactions: Partition, Toxicity, Bioaccumulation and Biological Concentration Factors

In this study we carried out batch cultures for investigating Zn-Nitzschia closterium (Ehrenberg) W. Smith interactions: partition, toxicity, bioaccumulation and biological concentration factors (BCFs). Individuals of the marine diatom were isolated from Sepetiba Bay (Rio de Janeiro, Brazil) — a semi enclosed body-water mostly contaminated for heavy metals like Zn, Cd, Cr and Pb. In the laboratory N. closterium was grown and exposed to a series of zinc concentrations (from 7 (control) to 1,1120 µg L -1 ) spiked with a fixed amount of radioactive 65 Zn (110 Bq mL -1 ). Toxicity effects of Zn-water concentrations in N. closterium were evaluated on exponential growth rates, µ, and also regarding 96-h exposure time for estimating the effective concentration to reduce, relative to the control, 50% N. closterium standing crop. No inhibition was observed on µ with Zn-water increase, but we found an estimated 96h-EC50 of 1,019 µg Zn L -1 . The other interactions, partition,