부산대학교 도서관

In the present study, the dissolved uptake, dietary assimilation, and elimination of arsenic (initially added as arsenate) in the freshwater cladoceran Daphnia magna were examined. A biphasic correlation between the arsenic uptake rate and its ambient concentration, as well as a two-saturation-site arsenic uptake competition with phosphate was observed. The calculated uptake rate constant, as influenced by the ambient phosphorus concentration, ranged from 0.035 to 0.35 L/g/d. Food concentration substantially decreased (by 23.2-64.4%) the arsenic assimilation efficiency with the incipient limiting algal food concentration of 3.86 mg/L dry weight. Arsenic assimilation by the daphnids was independent of their own phosphorus status, but was lower when their algal diet was phosphorus-limited and thus contained a higher proportion of arsenite due to the enhanced biotransformation. Arsenic efflux rate constant ranged from 0.34 to 0.44 d−1 with increased food concentration slightly facilitating its loss. Excretion, accounting for 51.3 to 60.6% of total loss, was the dominant pathway for arsenic elimination with a remarkable contribution from offspring production (24.7-29.8%), whereas molting (3.64-4.05%) and egestion (7.9-11.9%) had minor roles only. According to the well-established biokinetic model, dietary assimilation was predicted to be the main pathway for arsenic bioaccumulation in the daphnids, and arsenic has a great potential to be biodiminished along the food chain. Environ. Toxicol. Chem. 2012;31:1283-1291. © 2012 SETAC [ABSTRACT FROM AUTHOR]