氨氮与镉单一和复合作用对沉水植物穗花狐尾藻和轮叶黑藻光合能力的影响

Effects of Both Single and Combined Pollution of Cd and NH^+_4 on Hydrilla verticillata and Myriophyllum spicatum

在水-土环境中,单一物质引起的污染很少,绝大多数污染是多种污染物质共存所造成的.利用碘量法测定溶解氧,研究了氨氮与镉单一和复合作用对沉水植物穗花狐尾藻和轮叶黑藻光合能力的影响.结果显示,氨氮浓度在4.0 mg.L-1时,对轮叶黑藻有较强的胁迫作用,表现为光合作用的产氧量与呼吸作用的耗氧量均下降,而此浓度对穗花狐尾藻没有表现出胁迫作用;当镉处理浓度为0.2 mg.L-1时,镉对2种沉水植物都表现出明显的胁迫效应,且对轮叶黑藻的胁迫作用更强;当镉与氨氮复合作用时,对轮叶黑藻产生联合毒害作用,但对穗花狐尾藻毒害作用较轻,可能原因是穗花狐尾藻所含的粗纤维比轮叶黑藻少,细胞壁上能结合重金属的位点较少,所以吸附的镉相应减少,毒性较小.实验结果表明在进行湖泊水生植物修复时,相对于轮叶黑藻,穗花狐尾藻更适合作为生态恢复的先锋物种.

Combined pollution is more ubiquitous than the single pollution in water and rail environment. Iodine method was used to study the effects of both single and combined pollution of Cd and NH4^＋ on Hydrilla verticillata and Myriophyllum spicatum. Results came out that H. verticillata was distinctly stressed at 4.0 mg· L^- 1 concentration of NH4^＋ , oxygen production of photosynthesis and oxygen depletion of respiration all declined, but for M. spicatum, it was not be stressed. If treated with 0.2 mg·L^-1 Cd, H. verticillata and M. spicatum all were stressed, and H. verticillata was stressed more seriously. Combined pollution of Cd and NH4^＋ produced cooperative adverse effects on H. verticillata. But for M. spicatum, the stress was less severe comparatively. The main reason was that M. spicatum made of less crude cellulose. So it had less combined pathway with heavy mental than H, verticillata. It demonstrated that M. spicatum is suit for pioneer plant comparatively during the process of lake restoration.