菹草和伊乐藻对水-沉积物界面磷迁移转化的影响

Effects of Potamogeton crispus L. and Elodea nuttallii on Phosphorus Migration and Transformation between Water and Sediment

冬季沉水植物普遍凋亡,死亡残体易造成湖泊二次污染.为探究冬季耐寒性沉水植物对水-沉积物界面各形态磷迁移转化的影响,选取根系特征不同的冬季耐寒性沉水植物菹草(Potamogeton crispus L.)和伊乐藻(Elodea nuttallii)作为研究对象,测定其冬季生长期间上覆水、间隙水和沉积物中各形态磷的含量,并监测环境因子的变化.结果表明:①菹草、伊乐藻组生长期间水-沉积物界面各形态磷含量总体呈下降趋势,并在一定时期维持较低水平,菹草对沉积物和间隙水磷的吸收效果优于伊乐藻,而伊乐藻对上覆水磷的影响大于菹草.②试验第30天后,菹草、伊乐藻组上覆水和间隙水各形态磷质量浓度均显著低于对照组(P<0.05),上覆水中ρ(TP)最低值分别为0.057和0.041 mg/L,间隙水中ρ(DTP)(DTP表示溶解性总磷)分别维持在0.270~0.505、0.384~0.507 mg/L之间.③试验结束时,菹草组沉积物中w(TP)、w(IP)(IP表示无机磷)和w(NaOH-P)(NaOH-P表示NaOH提取态磷)分别低至643.68、415.79和120.17 mg/kg,分别下降了16.54%、18.37%和35.82%,伊乐藻组分别低至700.39、457.87和145.29 mg/kg,分别下降了10.24%、11.17%和24.67%;菹草、伊乐藻植株体内TP质量分别增加了588.94和464.59 mg.研究显示,菹草、伊乐藻在生长期间均能有效吸收磷,同时改变了pH、Eh等环境因子,从而影响磷在水-沉积物界面的迁移及磷形态的转变.

Many submerged macrophytes die in winter,and the decomposition of their organic bodies may result in secondary pollution.To clarify the effects of submerged macrophytes which grow in winter and are tolerant of cold water on phosphorus migration and transformation in water-sediments bodies,two submerged macrophytes with different root characteristics,Potomageton crispus L.and Elodea nuttallii,were used as the research objects.The concentrations of different phosphorus fractions in overlying water,interstitial water,and sediments during the growth period were measured,and the changes in environmental factors were simultaneously monitored.The results showed that:(1)During the growth period of Potamogeton crispus L.and Elodea nuttallii,all fractions of phosphorus in overlying water,interstitial water and sediments tended to decrease and maintained low over a period of time.In the case of absorbing phosphorus from sediments and interstitial water,the Potamogeton crispus L.was better than Elodea nuttallii.However,in the case of absorbing phosphorus from overlying water,Elodea nuttallii was better than Potamogeton crispus L..(2)On the 30th day of the experiment,the concentrations of all phosphorus fractions in the overlying water and interstitial water under the two submerged macrophytes treatments were significantly lower than those in the control group(P<0.05).The lowest concentrations ofρ(TP)in overlying water under the Potamogeton crispus L.and Elodea nuttallii treatments were 0.057 and 0.041 mg/L,respectively,and the concentrations ofρ(DTP)in the interstitial water under the Potamogeton crispus L.and Elodea nuttallii treatments maintained at 0.270-0.505 and 0.384-0.507 mg/L,respectively.③At the end of test,the concentrations of w(TP),w(IP)and w(NaOH-P)in the sediments under the Potamogeton crispus L.treatment decreased to 643.68,415.79 and 120.17 mg/kg,with removal rates of 16.54%,18.37%and 35.82%,respectively,and those under the Elodea nuttallii treatment decreased to 700.39,457.87 and 145.29 mg/kg,with removal rates of 10.24%,11.17%and 24.67%,respectively.The TP in Potamogeton crispus L.and Elodea nuttallii bodies increased by 588.94 and 464.59 mg,respectively.The results showed that Potamogeton crispus L.and Elodea nuttallii could effectively absorb phosphorus during growth period,and could change the environmental factors,such as pH and Eh.Consequently,the two submerged macrophytes had an obvious effect on phosphorus migration and transformation in water-sediments bodies.