天然水中氮素形态对菹草富集和降解DBP作用的影响

菹草是典型的沉水植物，在水体污染修复与生态重建中起重要作用．从海河干流和2个小型景观湖泊采集了4个氮素含量、氮素形态组成不同的水样，利用组培菹草研究了氮素形态对菹草富集和降解邻苯二甲酸二丁酯（DBP）作用的影响．结果表明：海河水中NO-3-N为氮的主要形态（59．4％～59．6％），湖泊水中NH4~-N为主要形态（47．7％～6712％）；随着水中N03-N含量的增加，菹草对DBP的降解速率常数（0．8×10-2～11．7×10-2d-1）随之增大，植物富集系数（0．94～7．43L／kg）也相应增大．进一步研究了菹草对水中不同形态氮素的吸收作用及生理指标（叶绿素、可溶性蛋白和硝酸还原酶活性）变化发现，菹草主要吸收利用水中的N03-N，菹草的生理指标也主要受N03-N含量的影响；N03-N含量增加，菹草的生理活性增大．这说明N03-N含量较高的水中菹草的活性较高，菹草对DBP的富集和降解作用增强．

Effects of Nitrogen Forms in Natural Waters on Accumulation and Biodegradation of DBP by Potamogeton crispus L.

Potamogeton crispus L. （P. crispus） is a typical submerged plant and plays an important role in the water pollution restoration and ecological reconstruction. Four natural water samples （from Haihe River and two small land scape lakes）, with different concentrations of nitrogen （N） and different characteristics of N forms, were selected to research the effects of N forms on biodegradation and accumulation of dibutyl phthalate （DBP） by P. crispus which was obtained by tissue culture technique. The results show that N0a-N is the dominant N form in water form Haihe River （59.4%-59.6%）, while NH4＋-N is the dominant N form in the water from the lakes （47.7%-67.2%）. With increasing NO3-N content, the biodegradation rate constant of DBP by P. crispus（0.8 ×10-2-11.7 × 10-2d-1） in creases, and the plant enrichment factor （0.94-7.43 L/kg） also increases. Further investigation on the absorption of different N forms by P crispus and variation of physiological indicators （chlorophyll, soluble protein and nitrate re ductase activity） was carried out. The results reveal that NO3-N is the main form to be absorbed by P crispus, the physiological indicators of which are mainly affected by NO3-N content. The physiological activity of P. crispus in creases with increasing NOg-N content. It can be concluded that natural waters with higher NO3--N content facilitate the activity ofP crispus and consequently accumulation and biodegradation of DBP by P crispus increase.