Pattern Optimization And Function Enhancement Technique Of Riparian Buffer Zone In Ashi River Basin

After the effective control of point source pollution,non-point pollution has become the main pollution source affecting the water environment quality of the basin.Riparian buffer zone is generally acknowledged as the effective intercept tool of NPS pollution,however,due to the lack of area,width and high degree of fragmentation,most of the riparian buffer zones in our country have poor function of purifing non-point source pollution and seriously affect the surface water health.In this study,riparian buffer zone as the research object,aims to strengthen the fouction by the biological and chemical enhancement as the research perspective,trying to make a contribution to the non-point source pollution removal and surface water and health by strengthening technology of riparian buffer function in china.This paper argues that the riparian buffer function can be enhanced by the method of biology and chemistry,and through the optimization design of the width of riparian buffer zone can effectively block the non-point source pollution,the following is the main content of this article.Riparian buffer zone is generally acknowledged as an effective intercept tool for non-point source(NPS)pollution control,however,due to lack of area,width and high degree of fragmentation,most riparian buffer zones in China have poor function of purifying NPS pollution and therefore affects the health of surface water bodies.In this study,the aim is to strengthen the function of buffer zones through biological and chemical enhancement and make contribution to non-point source pollution removal in China.This paper argues that riparian buffer function can be enhanced by the method of biology and chemical,through an optimization design of the width of riparian buffer zone.In view of the absence of spatial distribution map and low function of riparian buffer zone in Ashi River Basin,the spatial distribution of buffer zone was analyzed and the reasons for its low functioning were observed.In order to facilitate the analysis,the River Basin with its administrative boundary,soil distribution,land use distribution,slope degree distribution and function orientation difference was divided into 5 functional areas,where the analyses were based on f unctional partition.The result indicates that in area 1 and 2,riparian buffer zone is densely distributed,with wide area and high space continuity.But in areas 3,4 and 5,riparian buffer zone is missing,with high discrete fragmentation degree and obviously insufficient area.Space structure status in existence does not match with its functional requirements.The biological enhancement and chemical enhancement of the riparian buffer zone were studied in view of the low function of riparian buffer zone of the Ashi River Basin.The screening of grasses for Ashi river riparian buffer zones,three varieties of grasses namely Kentucky bluegrass,tall fescue and creeping bent grass were compared in terms of cost,growth characteristic,photosynthesis efficiency and removal effect of NPS pollution,the results shows that Kentucky bluegrass is comparatively in ascendant of the three plants.Kentucky bluegrass is suggested as the alternative vegetation used in riparian buffer zones in the northeast cold region of China.In addition,Microbial background needs to be understood before the riparian buffer zone is biologically enhanced.Using high-throughput 454 molecular sequencing technologies to analyze the microorganisms in riparian buffer zones,The results shows that the pathogen was enriched in the primitive environment(The content of Aeromonas was 9.7% and the content of Bacteroides was 6%).At the same time,it is found that AMF(arbuscular mycorrhizal fungi)is indigenous bacteria,but the content is low,which is not conducive to t he function.In the study of bioaugmentation of riparian buffer zones,strengthening the simulation riparian buffer zones by AMF microbial inoculum,using mixed inoculation of Glomus mosseae and Glomus intraradices,the ratio as 1:1,for bioaugmention,the amount added is 300g/m2.The results showed that the content of AMF was more than before adding AMF biological agent,and the amount of fungi was less than that before adding.As its removal rates of TN,TP and organic pesticide atrazine are 1.20,1.10 and 1.11 times of ordinary riparian buffer zones.In the study of chemical intensification of riparian buffer strips,light auxiliary electric catalytic system composed of N-S-Ti O2 NCs/ Ti O2 NTs-AC/PTFE was used,the removal rates of TN,TP and organic pesticide atrazine in the riparian buffer zones with chemical reinforcement are 2.35,2.07 and 6.97 times of strengthened riparian buffer zones..Using the SWAT model to calculate NPS pollution load of the Ashi River Basin(1200m on both sides of river),which have a greater influence on the surface waters.The results shows that in region 1 and 2,pollution load is low;in the areas 3,4 and 5,pollution load is high.On the basis of pollution load calculation,the concentration of non-point source pollutants in surface runoff flow to the riparian buffer zone edge was calculated,the results show that the 1 functional areas in the riparian buffer required width 19.3m,functional area 2 riparian buffer required width 36.13 m,required width of riparian buffer zones in 3 functional areas of 36.91 m,functional area 4 required the width of riparian buffer 47.96 m,functional area 5 required width of riparian buffer zones 45.11 m.According to the research,making an optimizational design for the riparian buffer zone.Functional area 1 and 2 in riparian the buffer zone are in good state,resulting in low non-point source pollution load,mainly taken to repair damaged riparian buffer zone to the corresponding necessary width;In the areas 3,4,and 5,the condition is the same and pollution load is high,due to mainly taken methods of bioaugmentation and chemical strengthening technology combined,in the main functional area 3,will strengthen the application of biological,riparian buffer width up to 33.55 m,enhanced biological function;in functional area 4,the average width of 4 functional areas in the native riparian buffer was 38.86 m,the purification rate under the condition of riparian buffer after bioaugmentation with width of 41.01 m,the functional areas in the riparian buffer zone can be considered with biological method,enhanced the riparian buffer width up to 41.01 m,then using AMF enhanced biological agents;in functional areas 5,due to the existing shore the lack of buffer width is too large,according to the situation of bioaugmentation and chemical strengthening,in the densely populated areas of riparian buffer zone of bioaugmentation,the width of up to 55.87 m,the population density is low and the farmland intensive place,can be used for chemical reinforcement,the width of riparian buffer should extend to 29.69 m by using the chemical enhancement.In some places can use biological and chemical enhancement together.