The Control Effect Of Riverside Buffer Zone On Non-point Source Pollution Of Liaohe River

Taking Liaohe River Basin in Jilin Province as the research object,aiming at the characteristics of non-point source pollution entering rivers with snowmelt in spring and weak purification ability of river discharge,in order to screen plant varieties with strong cold resistance and pollution interception ability,reveal the mechanism of cold resistance and pollution interception of selected plants,give full play to the strengthening role of plant rhizosphere microorganisms,and make full use of ecological niche principle.To scientifically construct the riparian vegetation buffer zone suitable for the severely polluted tributaries,and to improve the effect of pollution interception,relevant research has been carried out to condense the riparian buffer zone pollution prevention and control technology.(1)Using potted method and simulated trough method,it was preferred that plants such as Salix matsudana,Prunus padus,Spiraea japonica,Medicago sativa,and Trifolium repens.had higher purification rate of TN;Salix matsudana,Fraxinus mandschurica,Spiraea japonica,Spiraea japonica,Trifolium repens and Festuca arundinacea had strong purification ability for TP;plants such as Prunus padus,Salix matsudana,Spiraea japonica,Swida alba,Festuca arundinacea and Trifolium repens.had better purification effect on COD.The plant combination “Salix matsudana + Fraxinus mandschurica + Amorpha fruticosa + Spiraea japonica + Medicago sativa + Trifolium repens” had the highest purification rate for TN and TP.The plant combination “Salix matsudana + Prunus padus + Spiraea japonica + Swida alba + Trifolium repens” had the best effect on COD purification.(2)During the freeze-thaw period,plants had significant purification effects on TN and TP in runoff and seepage,and there were significant differences among plants.Trifolium repens,Poa pratensis,and Salix matsudana.had better purification effects on pollutants than other plants during the freeze-thaw period.Trifolium repens Linn.had the best purification effect on TN and TP in runoff and seepage in growing season.During the freeze-thaw or growing season,the purification rate of pollutants in runoff and seepage increased with the increase of temperature,but decreased with the increase of temperature.The results make up for the deficiencies of the study on the interception of non-point source pollution by vegetation buffer zone in northeastern China during freezing-thawing period.(3)Comparing the change of total nitrogen in matrix and the purification effect of TN in seepage with or without three AMF fungicides,the results showed that the reduction rate of total nitrogen in matrix would be significantly increased under the application of fungicides.The strengthening effect of fungicides reached 26.9-34.4%,and the order from high to low was Trifolium repens > Amorpha fruticosa > Medicago sativa > Poa pratensis > Spiraea japonica > Salix matsudana,AMF fungicides enhanced the purification of TN in seepage from growing season to freezing season,then decreased,and rose again in spring thawing period.The strengthening effect of AMF fungicides on Trifolium repens,Amorpha fruticosa and Medicago sativa was better than that of other plants.(4)By establishing regression equation between buffer width,slope and pollution purification rate,it was found that the purification rate of vegetation buffer zone to TN,TP,COD and other pollutants was positively correlated with buffer width,negatively correlated with buffer slope,and the effect of width on purification rate was significantly greater than slope.The effect of plant combination “Salix matsudana + Amorpha fruticosa + Trifolium repens” is the best.Taking the vegetation buffer zone with 15+5 m bank width as an example,the logarithmic equation of "plant combination+20° slope+15 m width" is validated by the monitoring results of purification rate of TN,TP and COD,and the fitting results are better.The optimal vegetation buffer zone for controlling agricultural non-point source pollution in Liaohe River Basin of Jilin Province was constructed,which effectively intercepted TN,TP and other pollutants.? The comprehensive technology of artificial intensification of pollution control in riparian buffer zone,which consists of vegetation interception technology,high-risk zone pollution reduction technology,pollution control and ecological landscape coupling configuration technology,was condensed.