中国圆田螺壳在镉污染中的指示作用

采用室内水体直接暴露和微宇宙模拟暴露,研究了重金属镉(Cd2+)对中国圆田螺(CipangopaludinaChinensis)的毒性效应及其在田螺软、硬组织中的蓄积规律。结果表明,中国圆田螺的5d水体直接暴露半致死浓度(LC50)为6.15mg·L-1;壳长增长率可以作为Cd2+慢性污染胁迫的有效生物标志,浓度为0.15 mg·kg-1的Cd2+刺激田螺壳增长,而浓度为1.5 mg·kg-1的Cd2+抑制田螺壳增长。中国圆田螺的壳与软组织均能够蓄积镉,并且随着暴露时间和暴露浓度的增大,重金属Cd2+的蓄积量也增大,相比之下田螺壳的蓄积更为稳定;天津中心城区主要景观水体中国圆田螺镉污染现状调查也得到了同样的结果。这表明,中国圆田螺的壳可以作为淡水环境镉污染的生物监测的有效补充。

Indicating Cd Pollution by Snail Cipangopaludina Chinensis Shell

Sensitive organisms can be used as an indicator of environmental pollution. An indoor experiment was conducted to study the toxic effects of heavy metal cadmium(Cd²⁺) on river snail Cipangopaludina Chinensis and its accumulation in soft and hard tissues of the snails using direct exposure and microcosm exposure. The 5 d half lethal concentration(LC₅₀) of cadmium to river snail was 6.15 mg·L^-1 under direct exposure. The growth rate of snail shell length could be considered as an effective biomarker of chronic Cd stress. Cadmium stimulated snail shell growth at 0.15 mg·kg^-1, but inhibited it at 1.5 mg·kg^-1. Cadmium could be accumulated in snail shell as well as in the soft tissue. The accumulation of Cd in soft and hard tissues increased with increased exposure time and concentrations. Moreover, Cd accumulation was more stable in the shell than in the soft tissue. The similar results were found in an insitu investigation of heavy metal pollution in the major landscape rivers in Tianjin. In conclusion, Cipangopaludina Chinensis shell could be an effective supplementary in biological monitoring of Cd pollution in freshwater environment.