title: The effect of humic acid on uptake/adsorption of copper by a marine bacterium and two marine ciliates.
abstract: The effect of humic acid (HA) on Cu uptake by a bacterium and two bacterivorus ciliates was investigated. The presence of HA resulted in a statistically significant (p<0.001) decrease in Cu associated with bacteria that were exposed to 67 microg Cu L(-1). Complexation of Cu appears to lower the availability of Cu with respect to bacterial cell surface binding and uptake. For ciliates, 10 mg HA L(-1) significantly reduced uptake of Cu by Uronema, but did not reduce uptake of Cu by Pleuronema. Uronema exposed to 67 microg Cu L(-1) accumulated 54% less Cu when 10 mg HA L(-1) was present (0.50 pg ciliate(-1) vs 0.23 pg ciliate(-1)). Uronema feeding on V. natriegens, took up less than half as much Cu as unfed Uronema when exposed to Cu without HA (0.41 pg Cu fed ciliate(-1) vs 0.86 pg Cu unfed ciliate(-1), but only 40% less when exposed to Cu and HA (0.31 pg Cu fed ciliate(-1) vs 0.51 pg Cu unfed ciliate(-1)). The lower % reduction attributable to fed ciliates in the presence of HA suggests that some of the Cu associated with HA is available through trophic processes.
authors.affiliation: U. S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, FL 32561, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Lores
authors.forename: R A
authors.initials: RA
authors.lastname: Snyder
authors.forename: J R
authors.initials: JR
authors.lastname: Pennock
mesh_terms: D000818:Animals; D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D016798:Ciliophora / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D006812:Humic Substances / Q000494:pharmacology*; D014733:Vibrio / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D006812:Humic Substances; D003300:Copper