【作者】 汤家喜；

【导师】 张玉龙；

【作者基本信息】 沈阳农业大学 ， 农业环境与生态， 2014， 博士

【摘要】 近年来,我国农业非点源污染所造成的水环境污染问题日益突出。作为水生生态系统和陆生生态系统过渡带的河岸缓冲带,可以有效地截留阻控农业非点源污染物向水体的迁移,降低农业非点源污染水体的风险。地处我国北方的辽河流域水环境质量受农业非点源污染较大。由于人们不合理的活动,局部地区河岸带植被遭受破坏,这使得这些地区河岸缓冲带对农业非点源污染阻控的功能下降。恢复和构建河岸缓冲带是阻控农业非点源污染较为有效的手段,但首先要选择较为适宜的河岸带植被,了解河岸缓冲带对非点源污染物的截留转化机理。本文在实验室植物筛选的基础上,构建草木犀带、草木犀与枫杨混合带(林草带)和杂草带(对照)三种类型人工河岸缓冲带,用野外小区试验的方法连续两年进行实地监测,从植被类型及其缓冲带宽度、植被季节变化、土壤酶活性以及微生物群落变化等方面,对河岸缓冲带阻控农业非点源污染的能力及其截留转化氮磷污染物的机制进行了系统的研究。所得主要结果如下：河岸缓冲带阻控农业非点源污染物的机制主要包括拦截地表径流、增加土壤渗透作用、植物和土壤吸收和吸附、土壤微生物的降解作用等。(1)总体上三种类型河岸缓冲带对农业非点源污染物阻控能力以林草带最强、草木犀带次之,杂草带最弱。草木犀草本植被适于构建研究区域河岸缓冲带。三种类型河岸缓冲带对阻控地表径流、降低径流中悬浮颗粒物浓度、质量和氮磷质量均有很好的效果；但降低径流氮磷浓度的效果不明显,降低土壤溶液中氮磷浓度的效果也因缓冲带类型及被阻控氮磷形态不同而表现出明显差异。(2)河岸缓冲带宽度是影响该缓冲带阻控能力的重要因子。河岸缓冲带越宽,其对农业非点源污染的阻控效果越明显：带宽5m以上,三种类型河岸缓冲带均可显著减少入河降雨径流流量、径流中氮素及悬浮颗粒物数量,林草带阻控能力最强,其截留效率达42%-99%之间,而除杂草带对氨态氮的截留效率最差；带宽9m以上,三种类型河岸缓冲带均可显著减少降雨径流中磷素数量。枫杨与草木犀的混合种植构建的缓冲带其阻控地表径流量、降雨径流中悬浮颗粒物和磷素数量的能力显著高于其它类型缓冲带,可能是由于该类型缓冲带生物量大、吸收氮磷数量多且土壤渗透能力强所致。(3)河岸缓冲带对污染物的阻控能力随季节而改变。三种类型河岸缓冲带阻控降雨径流的能力均显著大于阻控融雪径流能力。且河岸缓冲带宽度超过某一数值时阻控融雪径流中污染物的作用才明显,而融雪径流中污染物含量越高、其阻控效果则越不明显。冻融作用使缓冲带体系可溶性磷的含量增加,因此,该区域融雪径流可增大水体磷素污染的风险。(4)河岸缓冲带配置的植物对阻控农业非点源污染具有积极贡献。草木犀和枫杨对氮磷有较强的吸收与累积能力；七月份一次收割草木犀,其地上部分移除氮素数量达15.21-23.66g m-2,磷素0.72-1.02g m-2。(5)土壤微生物群落分布可作为河岸缓冲带阻控非点源污染氮磷能力的评价指标使用。土壤脲酶活性与河岸缓冲带体系对氮素的阻控作用之间并未表现出明显的相关性,而土壤磷酸酶活性与土壤阻控径流中磷素效果之间具有较好相关性。更多还原

【Abstract】 Water pollution has become a major problem for both developed and developing in recent decades. The contribution from agricultural non-point source pollution(ANSP) has become a major cause of water quality degradation in China. Riparian vegetated filter strips (RVFS), a zone of transition between aquatic ecosystems and terrestrial, can be effectively intercept ANSP into water bodies, and reduce the risk of pollution of water bodies. Liaohe River Basin located in northern China, the water quality is polluted by ANSP. Riparian vegetation has been damaged due to irrational activity by local people, RVFS’performance are deteriorating. It is an effective approach that recovering and building RVFS to reduce ANPS pollution load. But first it is important to choose more suitable riparian vegetation, and to understand the mechanism of conversion about ANPS. Three types of artificial RVFS demonstration area was built in the wild through screening plants in the laboratory, namely with sweet clover, sweet clover mixed with sweet clover/Chinese Wingnut and weeds (control), two consecutive years of field monitoring experiment was carried out by field plot test methods to examine the effects of RVFS in reducing ANSP and mechanisms and characteristics of RVFS in retaining ANSP in term of vegetation types, width, seasonal changes, soil enzyme activities and microbial community. The resulting conclusions are as follows:The mechanisms of RVFS in retaining ANSP include:intercepting surface runoff, vegetation, increased soil penetration, absorption and adsorption pollutants, microbial degradation and so on.(1) Overall, the capability of RVFS in retaining ANSP are followed by sweet clover/Chinese Wingnut> sweet clover> weeds. Sweet clover is appropriate to RVFS as herbaceous vegetation. Various types of RVFS can reduce effectively surface runoff, suspended particulate matter concentration and quality, nitrogen and phosphorus, but they have no significant effect on the concentration of nitrogen and phosphorus runoff of nitrogen and phosphorus concentration in the soil solution resistance control effect are different according to the type of RVFS and different forms of nitrogen and phosphorus.(2) The width of RVFS is an important factor to affect the ability to reduce ANSP. The wider of RVFS, the more obvious these effect on ANSP,5m wide RVFS can significantly reduce rainfall runoff, quality, and quality of suspended particulate matter in rainfall runoff of nitrogen, the ability of tree/grass filter is strongest, and retention efficiency is the range of42%-99%. The retention efficiency of sweet clover for ammonia nitrogen is low.9m wide RVFS can significantly reduce the quality of rainfall runoff phosphorus. The effect of tree/grass filter is better than the other filter in reducting ANPS. It is may be due to the larger band grass biomass, phosphorus accumulation ability of the reasons, and infiltration may be another major contaminant removal mechanism.(3) Seasonal changes significantly affect the effect of RVFS in reducting ANPS. The effect of RVFS on resistance of rainfall runoff is significantly greater than that of snowmelt runoff. Only the width of the riparian buffer exceeds a certain value, the resistance of snowmelt runoff pollutants was obvious, and snowmelt runoff pollutants content is higher, its resistance control effect is less obvious. Freeze-thaw effect can increase the content of soluble phosphate of buffer system, therefore, snowmelt runoff of this area can increase the risk of snowmelt runoff water soluble phosphorus pollution.(4) The plants in the riparian buffer zone can contribute to the resistance control agricultural non-point source pollution. Melilotus and Pterocarya have a strong ability of adsorption and accumulation for nitrogen and phosphorus. Taking a harvest for melilotus in July, the mount of nitrogen removed by the above-ground part can be in the range of15.2123.66g m-2, and the phosphorus in the range of0.72-1.02g m-2.(5) The distributions of soil microbial community of Melilotus and Pterocarya riparian buffers tend to be diverse, belonging to the type of bacteria. The characteristics of distributions can be regarded as one indicator for evaluating the riparian buffer resistance control non-point source pollution of nitrogen and phosphorus ability. The relationship between Soil urease activity and riparian buffer system and nitrogen resistance control has shown obvious correlation, and the tie between soil phosphatase activity and soil resistance control for phosphorus removal effect has a good correlation.更多还原