美人蕉（Canna indica Linn.）和芦苇（Phragmites australis L.）人工湿地对含铬生活污水的净化效果及植物的生理生态变化

选取美人蕉（CannaindicaLinn.）、芦苇（PhragmitesaustralisL.）为植物材料,以不同浓度K2Cr2O（7分别含0、1、20、50mg.L-1Cr6＋）的生活污水作为Cr6＋污染源,研究了不同浓度Cr6＋及处理时间下两种湿地对污水净化效果、植物体Cr6＋积累量及根系活力（TTC）、叶片超氧化歧化酶（SOD）活性、过氧化物酶（POD）活性、净光合速率（Pn）和丙二醛（MDA）等生理指标的影响。结果表明：（1）在试验的初期30d内,随处理时间的延长,两种人工湿地COD、氨氮去除率均呈逐渐上升的趋势,30d后,随着Cr6＋处理时间的延长及Cr6＋浓度的逐渐升高,两种湿地系统对COD、氨氮去除率均逐渐下降。在20、50mg.L-1Cr6＋处理条件下,两种湿地对COD、氨氮的净化效果显著低于对照及1mg.L-1Cr6＋处理,对照与1mg.L-1Cr6＋处理条件下差异不显著。（2）在不同Cr6＋浓度处理下,两种人工湿地对TP净化效果的能力较为稳定,同时随处理时间的延长,美人蕉、芦苇体内Cr6＋积累量逐渐加大。（3）1mg.L-1Cr6＋处理可提高美人蕉和芦苇的TTC、叶片的SOD、POD、Pn,而20、50mg.L-1Cr6＋处理对以上指标均有不同程度的抑制作用,且抑制效果与处理浓度、时间呈正相关。（4）MDA含量随处理时间的延长和浓度升高呈逐渐增加趋势。可见,低浓度Cr6＋能有效促进美人蕉、芦苇生长,使之能够维持正常的净化功能,因此,利用它们作为人工湿地植物来修复Cr6＋污染具有一定的实用价值。

Chromium Purification Effects on Domestic Wastewater and Physiological Changes of Canna indica Linn.and Phragmites australis L.in Constructed Wetlands

Domestic wastewater with four Cr6＋ concentrations（0,1,20,50 mg·L-1）was irrigated,to study the chromium purification effects on domestic wastewater and physiological changes of Canna indica Linn.and Phragmites australis L.in constructed wetlands.,The results were as follows：（1）The removal rate of COD and ammonia nitrogen of two wetlands increased with the time during the initial 30 days of the experiment and then decreased gradually with the increase of Cr6＋ concentration and time in domestic wastewater.Under 20 mg·L-1 and 50 mg·L-1 Cr6＋ treatment,the purifying effects of two constructed wetlands were significantly lower than the those of 1 mg·L-1Cr6＋ treatment and control.（2）Under four Cr6＋ concentrations,the purification effect of TP was stable,the accumulation of Cr6＋ increased gradually in plants with the increase of Cr6＋ concentration and time.（3）TTC,SOD,POD and Pn were enhanced under 1 mg·L-1 Cr6＋ but.inhibited under 20,50 mg·L-1 Cr6＋.The inhibition had a positive correlation with the concentrations of Cr6＋ and treating time;（3）The MDA content increased gradually with treating time and Cr6＋concentration.It suggested that low concentration of Cr6＋ can promote the grow of Canna indica Linn.and Phragmites australis L.and the purification function of the plants can be maintained.Therefore,the constructed wetlands with Canna indica Linn.and Phragmites australis L.can be used to purify low concentration chrome-containing wastewater.