植物净化富营养水体过程中温室气体变化及影响因素初探

Preliminary study on the changes and influencing factors of greenhouse gases during the purification of eutrophic water by plants

本文通过人为添加氮磷模拟水体富营养化,选用常见水生植物设置5个植物净化处理,研究水生植物在净化富营养化水体的过程中,温室气体(CO_(2)、CH_(4)、N_(2)O)的排放特征以及影响因素.结果表明:5个处理的水-气界面CO_(2)排放通量在19.12~395.19mg/(m^(2)·h)之间,呈现先降后升的变化趋势.5个处理的水-气界面CH_(4)、N_(2)O排放通量在0.009~0.96mg/(m^(2)·h)、0.024~6.48mg/(m^(2)·h)之间,均呈现先升后降再升的变化趋势.多元逐步回归方程结果表明,底泥溶解性有机碳(DOC)、底泥氨氮(NH_(4)^(+)-N)、水体pH值、水体溶解氧(DO)、水体叶绿素a(Chl.a)共同影响着水-气界面CO_(2)、CH_(4)、N_(2)O排放通量,其中底泥溶解性有机碳(DOC)对水-气界面CO_(2)、CH_(4)、N_(2)O排放通量均存在显著的促进作用,但水体pH值对水-气界面CO_(2)排放通量的影响在有沉水植物(处理1)的处理中为正作用,在无沉水植物的(处理2、处理3、处理4、处理5)影响为负作用.

Water eutrophication was simulated by artificially adding nitrogen and phosphorus,and setting up five purification treatments with aquatic plants.In our study,the CO_(2)effluxes at the water-air interface ranged from 19.12 to 395.19 mg/(m^(2)·h).The CO_(2)effluxes decreased slowly,and then increased.The CH_(4)and N_(2)O effluxes at the water-air interface ranged from 0.009 to 0.96mg/(m^(2)·h)and 0.024 to 6.48mg/(m^(2)·h),respectively.The temporal patterns of CH_(4)and N_(2)O effluxes were similar,which slowly increased,and gradually decreased,then eventually increased once again.The results of multiple stepwise regressions showed sediment DOC,sediment NH_(4)^(+)-N,pH,DO,Chl.a in the water were significant predictors of GHG effluxes at the water-air interface.Interestingly,sediment DOC had a significant promoting effect on GHG emission effluxes at the water-air interface.Especially,water pH had a positive impact on CO_(2)effluxes at the water-air interface in the treatment with submerged plants(Treatment 1),but negative in the treatment without submerged plants(Treatment 2,Treatment 3,Treatment 4,Treatment 5).