| The north slope of Qinling Mountain has an important strategic position for the protection of Qinling natural ecological system in Shaanxi Province, and it is the Qinling north line and the key regions to influence million people living environment quality of Guanzhong area. With the development of agricultural economy, agricultural non-point source pollution may affect the ecological environment quality in this area, but on the agricultural non-point source pollution state, the main pollution source and pollution ways remains unclear currently. Therefore, this study selected the Yu Jia River Basin in the,north slope region of Qinling Mountain as the research object, monitoring the spatial and temporal variation characteristics of the surface water quality during one year, evaluating the pollution grades, estimating agricultural non-point source pollution and its contribution, to explore the pollution characteristics and ways of fertilizers and pesticides in planting to surface water, to provide a theoretical basis for evaluating the effects of agricultural activities on the ecological environment scientifically and protecting ecological environment reasonably. The results showed that:The changes of water quality indicators were varied significant with time and space. The water quality status was affected by the rainfall obviously, and the difference of the water quality index in different sampling points increased with the rainfall increased.The water quality was influenced by land use, the upstream tributaries and residents’ life in the space.The ammonia nitrogen and TP concentration reached the national surface water III standard on the whole, TN and COD over the III water standard, which total nitrogen pollution is most prominent. Integrated the pollution from heavy to light, turned YJZ(1.85) > DY(1.71) >LM(1.67) > BXG(1.20).The standard pollution load of TN, TP and COD to Yujia river basin were 8.42×106,1.25×106,0.67×106 m3/a, and its pollutant contribution rate was TN> TP >COD, the major sources of pollution contribution rate was crop farming > sewage > livestock and poultry breeding. The standard pollution load of planting was 66.83%, and the pollution type of Yujia river basin belongs to the combined pollution of agricultural production and living. Totalnitrogen in four villages discharged into the river per unit time showed that the downstream was more than the upstream, and it showed LM>YJZ>DY>BAG. On the contrary, the concentration of TP and COD decreased in Yujia river basin, and its respectively showed DY>BXG> LM> YJZ and DY>LM> BXG>YJZ.The soil pH changes between 5.79~7.52, and it was neutral and acidic. The soil moisture content on the whole between 16.93%~30.10%, its size was mainly influenced by rainfall and soil properties. The organic matter in soil and surface water had no correlation, and TN in surface water and soil had significant correlation,No aureomycin was detected in soil of Yujia river basin, the content of oxytetracycline in0-20 cm was higher than that of tetracycline significantly, but in 20-40 cm tetracycline was only tetracycline detected.The tetracycline antibiotics content in soil appeared the highest value in December 2013, and the highest value in surface water appeared in March of the following year.The forchlorfenuron content in 0-20 cm soil layer was much higher than it in 20-40 cm soil layer. Its degradation rate was fastest between 7~16d, and the degradation rate arrived95.7% during 108 d. The half-life of forchlorfenuron was on the range of 6.42~24.21 d in this area, with an average half-life of 14.83 d. The soil pH and the forchlorfenuron residues had significant negative correlation, its correlation coefficient was-0.827(p<0.01).And the concentration of forchlorfenuron in surface water increased with the increase of the content of forchlorfenuron in soil, the highest concentrations were found in 19 June 2014. |
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