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An algal probe for copper speciation in marine waters: Laboratory method development
Author(s) -
Karner Dawn A.,
Shafer Martin M.,
Overdier Joel T.,
Hemming Jocelyn D. C.,
Sonzogni William C.
Publication year - 2006
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/05-214r.1
Subject(s) - thalassiosira weissflogii , copper , environmental chemistry , genetic algorithm , ethylenediaminetetraacetic acid , zinc , chemistry , bioavailability , chelation , nutrient , phytoplankton , inorganic chemistry , biology , ecology , bioinformatics , organic chemistry
Laboratory‐based algal assays were developed to explore the bioavailability of copper to the marine alga Thalassiosira weissflogii . A calibration strategy was developed that avoided use of the synthetic ligand ethylenediaminetetraacetic acid (EDTA) in the Aquil growth medium, thereby allowing ambient metal speciation. In a comparison of T. weissflogii cells grown in Aquil medium with EDTA to medium containing no added copper, zinc, and less than 0.003 nM of EDTA, no significant growth differences were observed after 8 d, indicating adequate stored nutrients. A 30‐h assay was selected as the optimal time frame after examination of data from concentration‐response experiments. Using 65 Cu stable isotope additions, parameters examined included growth, chlorophyll a , copper uptake, phytochelatin production, and dissolved organic carbon excretion. The T. weissflogii specific growth rates decreased from 1.36 d −1 at p Cu (i.e., the negative logarithmic concentration of free Cu) = 8.8 to 0.56 d −1 at p Cu = 7.8, whereas intercellular copper concentrations increased from 13.6 to 70.1 fg/cell, respectively. Calculated values of the copper concentration that caused a 50% reduction in algal growth of p Cu = 7.7 and copper per algal mass of 625 μg/g were established. Using an algal assay based on EDTA‐free culture medium, along with trace‐metal clean techniques, the effect of copper on T. weissflogii and the speciation of copper in marine waters can be studied.