Kinetics and Body Distribution of Waterborne 65Zn(II), 109Cd(II), 203Hg(II), and CH3 203Hg(II) in Phantom Midge Larvae (Chaoborus americanus) and Effects of Complexing Agents

• Published in: Environmental science & technology 1998-05, Vol.32 (9), p.1230-1236
• Main Authors: Rouleau, Claude, Block, Mats, Tjälve, Hans
• Format: Article
• Language: English
• Subjects: AQUATIC INSECTS; CADMIO; CADMIUM; CINC; INSECTE AQUATIQUE; INSECTOS ACUATICOS; MERCURE; MERCURIO; MERCURY; MERCURY COMPOUNDS; ZINC
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es970613k

Uptake, elimination and body-distribution of waterborne 65Zn(II), 109Cd(II), 203Hg(II), and CH3 203Hg(II) were studied in fourth instar larvae of phantom midge, Chaoborus americanus, using a two-compartment kinetic model and whole-body autoradiography (WBARG). The effects of complexation by sodium diethyldithiocarbamate (DDC) and humic material (HM) were also evaluated. Uptake of Hg(II) and CH3Hg(II) from water was 20−240 times higher after a 1 week exposure compared to Cd(II) and Zn(II). Unexpectedly, CH3Hg(II) uptake rate was 5 times slower than inorganic Hg(II). WBARG showed a strong CH3Hg(II) gradient between organs and haemolymph, indicating that its slower accumulation may be related to a slower rate of translocation within the body rather than to a difference in overall lipid solubility compared to Hg(II). DDC doubled the uptake rate of both Hg forms, probably as the result of lipophilic complexes formation, but its effect on Zn(II) and Cd(II) uptake was negligible. HM decreased uptake rate of Hg(II) by a factor 50, whereas it increased CH3Hg(II) uptake by 30%. These results cannot be explained solely from the complexation of dissolved Hg(II) and CH3Hg(II) by HM. They indicate that HM adsorbed on aquatic organisms could also directly affect the uptake process at the water−larvae interface.