寻乌废弃稀土矿区人工湿地4种植物净化水体氮的效果

Nitrogen Purification Effects of Four Plants Grown in the Constructed Wetland in Abandoned Rare Earth Mining Areas in Xunwu County,Jiangxi Province

【目的】不同湿地植物的生长特性一般有所不同,对于湿地水体的净化效果也会有所差异。因此,筛选适用于赣南废弃稀土矿区净化高氮而磷养分不足的人工湿地植物,可以为赣南稀土矿原位浸矿区人工辅助处理污水的湿地工程提供技术支撑,有利于改善赣南稀土矿区河流水质及环境质量。【方法】以位于赣南寻乌县废弃稀土矿区阶级式人工湿地为研究对象,选用4种常用人工湿地植物水葱(Scirpus validus)、再力花(Thalia dealbata)、芦苇(Phragmitescommunis)、美人蕉(Canna indica),测定了植物的地下和地上器官生物量、总氮、总磷、氮贮量,不同阶级净化池水体的氮磷浓度,对比评价了4种湿地植物净化水体氮的效果。【结果】4种湿地植物生长及氮磷贮量在不同阶级净化池中表现各异,单位面积生物量为芦苇最高,水葱次之,再力花和美人蕉最低;而氮贮量为芦苇最高,美人蕉次之,水葱和再力花最低;两者在地上和地下的分配比各异,但均为地上器官显著高于地下器官。第一、二、三级净化池中氨氮削减率依次为5.40%、13.51%、21.62%,第一级净化池氨氮含量显著高于第三级净化池;总氮削减率依次为19.30%、20.16%、23.48%,3个净化池的总氮含量无显著差异,削减率均随净化池阶级增加而提高。不同湿地植物磷含量和氮/磷比的异同取决于净化池,磷含量表现为地上器官低于地下器官,而氮磷比表现为地上器官高于地下器官。【结论】芦苇和美人蕉为研究区人工湿地构建的优先推荐植物,具有较高的净化能力,两者均更宜配置于第一级净化池,而再力花和水葱可分别配置于第二和第三级净化池。

[Objective]Different wetland plants have different growth characteristics,and their purification effects on wetland water are not the same.It can provide technical support for the wetland project of sewage purification under artificial supplementary in the in-situ leaching areas of the abandoned rare earth mines in the south of Jiangxi Province to select plants suitable for the constructed man-made wetland that purify excessnitrogen and deficient phosphorus nutrients,which is beneficial to improving the river water quality and environment in the rare earth mining areas of thesouthern JiangxiProvince[Method]Taking the class-type constructed man-made wetland located in the abandoned rare earth mining areas in Xunwu County,southern Jiangxi Province as the research object,four commonly used wetland plants,including Scirpus validus,Thalia dealbata,Phragmites communis,Canna indica,their belowground and aboveground organ biomass,total nitrogen,total phosphorus and nitrogen storage,total nitrogen and total phosphorus contents of the water in purification ponds at different levels were measured,and the effects of the wetland plants in removing nitrogen from the purification ponds were evaluated[Result]The results showed that the growth,total nitrogen and total phosphorus contents of the four wetland plants were significantly different in three purification ponds.The biomass per unit area was the highest in P.communis,followed by S.validus,and the lowest in T.dealbata and C.indica,and the distribution ratios of plant biomass between the belowground and the aboveground were different in the different classes of the purification ponds,but the aboveground biomass was higher than the underground biomass.And the nitrogen storage was the highest in P.communis,followed by C.indica,and the lowest in S.validus and T.dealbata,and the nitrogen storage in the aboveground organs of wetland plants were significantly higher than that in the belowground organs.The reduction rates of ammonium nitrogen in the first,second,and third classes of purification ponds were 5.40%,13.51%,and 21.62%,respectively,and the ammonium nitrogen content of the first class of purification pond was significantly higher than that of the third class of purification pond.The reduction rates of total nitrogen were 19.30%,20.16%,and 23.48%,respectively,and there was no significant difference in the total nitrogen contents of the three purification ponds.The reduction rates of ammonium nitrogen and total nitrogen all increased with the changes in the class of the purification ponds.The similarities and differences in the total phosphorus content and nitrogen/phosphorus(N/P)ratios of the four different wetland plants depended on the purification ponds,the total phosphorus content was lower in the aboveground organs than that in the belowground organs,while the N/P ratio was higher in the aboveground organs than that in the belowground organs.[Conclusion]Overall,emerged plants such as P.communis and C.indica might be preferentially recommended for the constructed man-made wetland in the study area.They have high purification capacity and both of them are more suitable to be planted in the first-level purification pond,while T.dealbata and S.validus should be separately planted in the second and third-level purification ponds.