Transport Law And Control Of Agricultural Non-point Source Pollutants In Hejiabang Creek Basin Of Tai Lake Region

Tai Lake suffered a lot from eutrophication. Although kinds of control measureshave been taken in years, the water quality wasn’t fundamentally improved, which isgreatly impacted by farmland non-point source pollution. Rainwater runoff is one ofthe most important ways to introduce the non-point source pollutants into lakes.Therefore, effective evaluation analysis of pollutant transport law and specific controlmeasures are of great importance to reduce the pollution in Tai Lake.In this task, a typical area of farmland in Hejiabang Creek basin surrounding TaiLake was chosen. Runoff water flow and its quality in ditches were monitored tosummarize dynamic patterns of rainfall and runoff flow and to obtain the dynamicmodels of runoff quality. Based on the runoff and pollutant transport processes, therainwater runoff pollutant transport law was studied, storm runoff scouring effectevaluation model was established and the quantitative evaluation on the scouringeffect intensity was carried out. Combined with basic data, the EMC (Event MeanConcentration) of pollutants, pollution load and the correlation law of main pollutantswere calculated. Furthermore, a point-line combination of agricultural non-pointsource pollution control measure was proposed.Results showed SS (suspended solids) in runoff had a strong positive correlationwith rainfall intensity, but had a weaker correlation with rainfall. Nitrogen sourceconcentration in runoff was subjected to its base value in farmland to a large degree,while rainfall intensity showed little influence. TP almost consisted with PP (particlephosphorus), while PO43--P concentration was in low level, indicating that PP is themain point in design of farmland non-point Phosphorus pollution control measures.The sources of nitrogen pollution and phosphorus pollution were same in non-pointpollution in farmland. The main forms of nitrogen were PN (particle nitrogen) and AN(ammonia nitrogen), both of them were far more than NN (nitrate nitrogen) and themain form of phosphorus pollution was PP. Low level of particulate properties ofpollutants resulted in weak first flush effect in rainfall-runoff. All the main indexes ofaverage rain wash effect (early) strength value I were SS (0.1114)＞PN (0.0464)＞PP(0.0378)＞TN (0.0365)＞TP (0.0206)＞AN (0.0194)＞NN (0.0135)＞PO43--P(0.0105) in order. Farmland runoff pollution levels in the study area were moreserious. The mean EMC value of three of main pollutants, TN, AN and TP were15.49mg/L,8.446mg/L and0.590mg/L, which are respectively6.67,3.32and1.95times higher than the surface water environment quality standards-class V, and their outputloads were285.1g/hm2,153.4g/hm2and11.52g/hm2, respectively. Pollutantrelativity showed significant difference at different monitoring points in runoff path.Pearson correlation coefficient values of SS-TN and SS-TP near pollution dischargeoutlets were up to0.832and0.925, while both of them showed even negativecorrelation at some downstream monitoring points. Relevant control measureproposed was modularized and miniaturized, which included fan-shapedladder-ecological revetment system and combinable backwashing purification system,providing a new train of thought for farmland non-point source pollution controltechnology development and promotion.