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Accumulation kinetics of arsenic in Daphnia magna under different phosphorus and food density regimes
Author(s) -
Miao AiJun,
Wang NingXin,
Yang LiuYan,
Wang WenXiong
Publication year - 2012
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 - 10.1002/etc.1822
Subject(s) - arsenic , daphnia magna , arsenate , environmental chemistry , chemistry , arsenite , bioaccumulation , phosphorus , assimilation (phonology) , toxicity , linguistics , philosophy , organic chemistry
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