[Changes in phototaxical index of Daphnia carinata under electric field of direct current in response to Cr6+ and Hg2+].
In order to detect toxicants sensitively in water by phototaxity of Daphnia, we studied the influence of DC electric field on phototaxity of self-bred Daphnia carinata, a mono-clone with high phototaxity, and the changes of their phototaxity in response to Cr6+ and Hg2+ after the treatment of DC electric field. The result indicated that the treatment of DC electric field changed their phototaxical indexes from positive to negative as the electric density increased and the time prolonged. The criteria values that showed no sign of changes in the phototaxical index of Daphnia carinata were 0.01 mA for 5 min. However, the limit for detecting Cr6+ and Hg2+ by their phototaxical index decreased significantly after treatment with 0.01 mA/5 min. The detection limits were only 32 microg x L(-1) for Cr6+ and 4.2 microg x L(-1) for Hg2+ after this treatment, much lower than those without pretreatment (56 microg x L(-1) for Cr6+ and 5.6 microg x L(-1) for Hg2+, respectively). Therefore, appropriate DC electric field to pre-treat Daphnia could decrease the detection limit, widen the concentration range of detection, and increased the sensibilities in water monitoring.
College of Resource and Environment, Southwest University, Chongqing 400716, China. wangfeixiang_15@126.com
Fei-Xiang
FX
Wang
Ling
L
Yuan
Jian-Guo
JG
Huang
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002857:Chromium / Q000032:analysis / Q000633:toxicity; D003621:Daphnia / Q000502:physiology*; D004560:Electricity; D004574:Electromagnetic Fields; D008027:Light; D008628:Mercury / Q000032:analysis / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity*; D060753:Water Quality
D014874:Water Pollutants, Chemical; D002857:Chromium; D008628:Mercury