title: Dietary bioavailability of Cu adsorbed to colloidal hydrous ferric oxide.
abstract: The dietary bioavailability of copper (Cu) adsorbed to synthetic colloidal hydrous ferric oxide (HFO) was evaluated from the assimilation of (65)Cu by two benthic grazers, a gastropod and a larval mayfly. HFO was synthesized, labeled with (65)Cu to achieve a Cu/Fe ratio comparable to that determined in naturally formed HFO, and then aged. The labeled colloids were mixed with a food source (the diatom Nitzschia palea) to yield dietary (65)Cu concentrations ranging from 211 to 2204 nmol/g (dry weight). Animals were pulse fed the contaminated diet and assimilation of (65)Cu from HFO was determined following 1-3 days of depuration. Mass transfer of (65)Cu from HFO to the diatom was less than 1%, indicating that HFO was the source of (65)Cu to the grazers. Estimates of assimilation efficiency indicated that the majority of Cu ingested as HFO was assimilated (values >70%), implying that colloidal HFO potentially represents a source of dietary Cu to benthic grazers, especially where there is active formation and infiltration of these particles into benthic substrates.
authors: U.S. Geological Survey, Menlo Park, California, USA. djcain@usgs.gov
authors: Daniel J
authors: DJ
authors: Cain
authors: Marie-Noële
authors: MN
authors: Croteau
authors: Christopher C
authors: CC
authors: Fuller
mesh_terms: D000327:Adsorption; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D003102:Colloids / Q000737:chemistry / Q000378:metabolism*; D003300:Copper / Q000302:isolation & purification / Q000378:metabolism*; D017377:Diatoms / Q000502:physiology; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism*; D020387:Food Chain; D049851:Gastropoda / Q000502:physiology; D007313:Insecta / Q000502:physiology*
chemical_list: D003102:Colloids; D005290:Ferric Compounds; C021024:ferric hydroxide; D003300:Copper