Cd、Pb、Cu、Zn、As复合污染对杂交水稻苗的联合生理毒性效应及临界值

The Combined Eco-toxicological Effect of Cd,Pb,Cu,Zn and As Pollution on a Hybrid Rice Seedling and the Critical Value

通过室内土培试验,研究了不同浓度的Cd、Pb、Cu、Zn、As等5种重金属复合污染对水稻苗的联合生理毒性效应,并对其临界值进行了探讨。结果表明:5种重金属污染对水稻苗的联合生理毒性效应随其污染浓度的增加而显著增强,剂量—效应关系明显。除处理(1)外,其余各处理对水稻苗体的诸项生长指标的抑制均达到了极显著的程度(P<0.01),且对根长的抑制明显大于苗长。随着复合重金属污染浓度的增大,水稻苗叶片中叶绿素含量急剧减少;丙二醛(MDA)含量迅速增加;POD和SOD酶活性呈先升后降的变化趋势。铅锌尾矿和矿毒水污染对水稻苗生长和各项生理生化指标的影响也均达到了极显著程度,但在二者污染下,POD和SOD酶活性均高于对照,铅锌尾矿的毒性效应大于矿毒水。以酶活性为参考指标,可以将土壤环境质量二级标准上限值设定为土壤中Cd、Pb、Cu、Zn、As等5种重金属对该水稻品种的临界毒性效应值。

The physiological toxic effect of different concentrations of Cd, Pb, Cu,Zn and As compound pollution was studied with a soil cultivation experiment. The result indicated that with the increasing concentration of compound heavy metals, the compound physiological toxic effect on the five kinds of hybrid rice seedling became stonger. The growth of the hybrid rice seedling was significantly inhabited by all the treatments except for the treamtment one. The tolerance of hybrid rice shoot to compound heavy metal pollution was stronger than it＇s root. With the heavy metal pollution intenstiy increasing,the total content of chlorophyll in the leaves of hybrid rice seedling dereased rapidly,and then the membrane - lipid peroxidation occurred in the leaves. This resulted in the increase of MDA, but the activity of POD and SOD increased first and decreased afterwards. Lead/Zinc mining tailings and toxic water also inhibited the seedling growth of the hybrid rice greatly. But,the activity of POD and SOD were activited in a certain degree and the physiological toxic effect of Lead/Zinc mining tailings was stronger than toxic water. It was reasonable that the upper value of heavy metals in the Second Grade National Environmental Quality Standard for Soil can be used as the critical value of Cd, Pb, Cu,Zn and As in the soil for the starting point of toxicity.