豆禾混播与生物炭互作去除径流污染物效果研究

发布时间：2018-09-15 05:43

【摘要】：近年来,农业面源污染已逐渐成为河流、湖泊等水体富营养化的重要污染来源,防治农业面源污染成为改善水质、治理水体富营养化的当务之急。植被缓冲带作为农业面源污染进入受纳水体之前的最后一道屏障,越来越成为环境科学领域的研究热点。国内外关于植被缓冲带已有大量的研究与报道,而利用豆禾草本混播技术或通过改变土壤质地来提高植被缓冲带对径流污染物质拦截效果的研究甚少。基于此问题,本试验利用豆禾混播技术、引入生物炭改变土壤质地来构建植被缓冲带,以期提高植被缓冲带对地表径流的拦截效果,并为探寻河岸边植被缓冲带新的构建技术提供理论依据。通过土柱模拟实验,研究不同比例生物炭用量(0%、2%、4%、8%和16%)对外源氮磷等污染物的拦截效果,其中16%生物炭用量的土柱系统在运行期间的污水下渗速度最高可达CK的9.43倍,TN拦截速度最大可达CK的9.05倍,COD拦截速率最大可达CK的16.34倍。不同处理对TN(进水浓度为30.16mg?L-1)、COD(进水浓度为510mg?L-1)均有很好的拦截效果,TN拦截率为95%左右,COD拦截率为63%左右。另外,生物炭中有效磷含量可显著影响土壤对外源磷素的拦截效果,应选择低磷含量的生物炭进行植被缓冲带的构建。采用16%的生物炭用量,在土柱模拟实验条件下,研究不同豆禾播种组合(单播处理:白三叶、黑麦草、紫羊茅、草地早熟禾;混播处理:白三叶与黑麦草1:3混播、白三叶与紫羊茅1:3混播、白三叶与草地早熟禾1:3混播)对外源氮磷等污染物的拦截效果,发现草本的加入能够显著提高土壤对外源污水的拦截量及污染物总拦截量,其中白三叶与黑麦草1:3混播处理的效果最为有效,TN拦截率在93%左右,COD拦截率在90%左右,并且相对CK,可最大提高污水拦截量127.16%,提高污染物总拦截量2.77%。利用不同草本组合、16%的生物炭用量构建长4m、宽2m、坡度为7o的植被缓冲带,发现白三叶与黑麦草1:3混播草带能够有效滞留地表径流,并提高污染物拦截量,并相对于白三叶单播、黑白草单播、紫羊茅单播、草地早熟禾单播、白三叶与紫羊茅1:3混播、白三叶与草地早熟禾1:3混播处理可提高污染物总拦截量3.29%、5.31%、5.56%、8.26%、3.98%和5.28%。本实验结果表明,通过16%生物炭用量来改变土壤质地,并利用白三叶与黑麦草1:3混播技术来构建植被缓冲带,可显著提高植被缓冲带对径流及径流中所携带的氮磷等污染物的拦截效果。
[Abstract]:In recent years, agricultural non-point source pollution has gradually become an important source of eutrophication in rivers, lakes and other water bodies. The prevention and control of agricultural non-point source pollution has become the urgent task of improving water quality and controlling water eutrophication. As the last barrier before agricultural non-point source pollution enters the receiving water, the vegetation buffer zone has become the research hotspot in the field of environmental science. There have been a lot of researches and reports on vegetation buffer zone at home and abroad, but few studies have been done to improve the interception effect of vegetation buffer zone on runoff pollution by using mixed sowing technology of soybean and grass or by changing soil texture. In order to improve the interception effect of vegetation buffer zone on surface runoff, biochar was introduced to change soil texture in order to improve the interception effect of vegetation buffer zone on surface runoff. It also provides theoretical basis for exploring new construction technology of riparian vegetation buffer zone. Through soil column simulation experiment, the interception effect of different ratios of biochar (8% and 16%) on exogenous nitrogen and phosphorus was studied. The soil column system with 16% biochar content has the highest infiltration rate of 9.43 times of CK and 9.05 times of CK and 16.34 times of CK. TN (influent concentration is 30.16mg?L-1) (influent concentration is 510mg?L-1) of different treatments have very good interception effect, TN interception rate is about 95% or so, COD interception rate is about 63%. In addition, the available phosphorus content in biochar could significantly affect the interception effect of exogenous phosphorus in soil, so low phosphorus content biochar should be selected to construct vegetation buffer zone. Under the condition of soil column simulation experiment, using 16% biochar, the different sowing combinations of soybean and grass (single seeding: White clover, ryegrass, purple fescue, bluegrass) were studied, and mixed sowing treatment: White clover and ryegrass were mixed at 1:3. White clover and purple fescue were mixed sowing at 1:3, white clover and Kentucky bluegrass were mixed sowing at 1:3) to intercept exogenous nitrogen and phosphorus, it was found that the addition of herbs could significantly increase the amount of soil interception of exogenous sewage and the total interception of pollutants. The most effective interception rate of TN was 93% or so, and the relative CK, could increase the sewage interception capacity 127.16% and the total pollutant interception capacity 2.77%. A vegetation buffer zone of 4 m long, 2 m wide and 7 o slope was constructed by using 16% biochar of different herbaceous combinations. It was found that the mixed sowing belt of white clover and ryegrass at 1:3 could effectively retain surface runoff and increase the amount of pollutant interception, and compared with single seeding of white clover. Black and white grass, purple fescue, bluegrass, white clover and purple fescue were mixed at 1:3, white clover and bluegrass were mixed with 1:3, the total intercepting capacity of pollutants was increased by 3.295.31% and 5.28%. The results showed that the soil texture was changed by using 16% biochar, and the vegetation buffer zone was constructed by the mixed sowing of white clover and ryegrass at 1:3. It can significantly improve the interception effect of vegetation buffer zone on runoff and nitrogen and phosphorus pollutants carried in runoff.
【学位授予单位】：中国农业科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52

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