生物炭与纳米碳对模拟植被缓冲带截留氮、磷污染物的影响研究

Effects of biochar and nano-carbon on the retention of nitrogen and phosphorus pollutants in simulated vegetation buffer zone

城市非点源污染是城市地表水体环境污染的主要原因,河岸植被缓冲带(以下简称缓冲带)是截留地表径流污染入河的有效措施。通过模拟实验法,利用土壤、植物(西伯利亚鸢尾(Iris sibirica L.))、生物炭与纳米碳构建缓冲带,对比不同添加量的生物炭与纳米碳对缓冲带拦截模拟径流入渗速率和模拟径流中主要污染物的影响。结果表明:20%(质量分数,下同)生物炭添加量可以显著提高系统对TN和COD的去除率,分别达到51.70%、97.50%;添加15%生物炭时累积拦截TN量最高,为322.56 mg。纳米碳由于堵塞土壤孔隙明显降低了模拟径流在基质中的入渗速率,不利于对模拟径流污染物的去除;缓冲带对模拟径流所携氮、磷的去除主要依靠基质的吸附、植物吸收以及微生物的贮存和促进利用等;添加15%与20%生物炭可显著增加土壤中微生物量,促进植被生长和吸收养分,使得缓冲带植被吸收氮、磷成为模拟径流中氮、磷去除的主要途径。研究结果将为实际工程应用提供数据参考,对减轻城市非点源污染具有重要的意义。

Urban non-point source pollution is the main cause of environmental pollution of urban surface water bodies.Riverside vegetation buffer zone(hereinafter referred to as buffer zone)is an effective measure to intercept surface runoff pollution into the river.To compare the effects of different dosages of biochar and nano-carbon on N and P interception in vegetation buffer zone,vegetation buffer zone was constructed with soil and plant(Iris sibirica L.),biochar and nano-carbon.Results showed that removal rates of TN and COD were 51.70%and 97.50%with 20%(mass fraction,the same below)biochar in the buffer zone.When 15%biochar was added,the buffer zone had the highest cumulative interception of TN,which was 322.56 mg.Nano-carbon blocked the soil pores,and it significantly reduced the infiltration rate of simulated runoff in the matrix,which was not conducive to the removal of simulated runoff pollutants.Matrix adsorption and plant absorption,as well as storage and utilization of microorganisms,contributed to N and P removal in runoff.Adding 15%and 20%biochar could significantly increase the microbial biomass in the soil,promote vegetation growth and nutrient absorption,making the absorption of N and P by vegetation in the buffer zone become the main way to remove N and P in simulated runoff.The results would provide data references for practical engineering applications and also had positive significance for reducing urban non-point source pollution.