| As an important tributary of the Songhua River, the Yinma River basin is now suffering from non-point source pollution, which has made the water quality from bad to worse. The continued deterioration of the water quality has seriously restricted the sustainable development of the social economy and destructed the living environment of the people in the basin, which has threatened the water quality safety of the Songhua River basin. By now, no research has been made on the pollution load of the Yinma River basin, the characteristics of the pollutants or the pollutant spatial-temporal pattern evolution. As a result, the pollution control of the Yinma River basin has not been paid close attention to, which limited the deepening of the non-point source pollution control and the river water environmental governance to a large extent.Taking the Yinma River basin as the research area, this research was made to improve the original runoff coefficient model based on the climate and geographical features of the Yinma River basin. Analog computation was conducted on the pollution loads of TN, TP and COD in the basin, which were comparatively analyzed with the computed results of the measured data calculated by average concentration method, and the relative error was proved in the allowable range. The runoff trend of the non-point source pollutants in different types of soil in the river basin was studied, and the law of the pollutant migration was revealed. The absolute emissions of the pollutants within a specific period of time were also calculated, and how the pollutant emissions of the 13 counties and districts changed with the time and the space was explored. The feature analysis of the main pollution problems was made, based on which corresponding measures for pollution control were proposed. The research results of this paper can provide scientific basis and decision support for the control and management of the non-point source pollution in the Yinma River basin, which also present great significance and value for the improvement of the water environment quality in the Yinma River basin and even the Songhua River basin, the construction of scientific living environment in the basin, and the promotion of the sustainable economic development of the Yinma River basin. This paper mainly includes the following contents: 1.Scientific Improvement for the Runoff Coefficient Model of the Yinma River Basin 2.Research on the Pollution Load of Non-point Source Based on the Measured DataThe pollution load of the non-point source was calculated based on the measured hydrologic data of the Yinma River basin, including the contribution rate of the pollutant emissions. Besides, the sources and constitutes of the non-point source pollution were analyzed, which can provide scientific basis for the non-point source pollution control in the Yinma River basin.(1) In 2004-2013, the contribution rate of TN emission ranked as farmland>livestock breeding>agricultural population. The farmland contributed the most to the TN pollution in the Yinma River basin, which reached up to 68.01%, and then livestock breeding and agricultural population followed.(2) In 2004-2013, the contribution rate of TP emission ranked as agricultural population>farmland>livestock breeding, which accounted for 35.22%, 31.31% and 28.51%, respectively.(3) In 2004-2013, the contribution rate of COD emission ranked as livestock breeding>agricultural population>farmland, which accounted for 83.42%, 14.35% and 1.44% respectively. 3.Analysis on the Change Trend of the Non-point Source Pollutants in 2004-2013(1) During the ten years in 2004-2013, the non-point source pollution of TN increased first and then kept constant.(2) During the ten years in 2004-2013, the non-point source pollution of TP showed a year-by-year increasing trend.(3) During the ten years in 2004-2013, the non-point source pollution of COD also showed a year-by-year increasing trend. 4.Analysis on the Law of Non-point Source Pollutant Migration in the Yinma River BasinRunoff plots were established in the Yinma River basin based on the land use type, including the dry farmland, the paddy field, the grassland and the woodland, so as to explore the law and characteristics of the non-point source pollutant migration in different land use types.(1) With the same rainfall capacity, rainfall intensity and terrain slope, the grassland and the woodland had lower runoff volume and speed slow, but the dry farmland and the paddy field were just the other way. Among all the land use types, in the early stage of the rainfall, the concentration of TN, soluble nitrogen, TP and soluble phosphorus reached up to the maximum before the runoff volume reached to its maximum. Along with the increase of the runoff volume, the concentration of the pollutants got lower.(2) From the perspective of the runoff of nitrogen, the runoff volume of the soluble nitrogen in the dry farmland and the paddy field accounted for a higher proportion of the total volume. The content of the soluble nitrogen was much higher. After the rainfall resulting in surface runoff, nitrogen mainly ran off in the form of soluble nitrogen.(3) The pollutant concentration of TP was at the maximum at the beginning of the runoff. With the continuous washing and scouring of the runoff, the pollutant concentration decreased gradually. At the end of the rainfall, the concentration of TP in the runoff reversed and then increased. From the perspective of the runoff form of the TP in the four land use types, the runoff volume of the soluble phosphorus just accounted for a small proportion of the total runoff volume of phosphorus, indicating that the sediments of the phosphorus accounted for a relatively higher proportion. The range ability of soluble phosphorus was relatively small, indicating that the volume and concentration of the components soluble under certain conditions were ranging within limits, and the influence of water environment conditions on the solubleness of the components was much more significant than that of the runoff. It could be seen that the range ability of TP runoff with the rainfall in the dry farmland and the woodland was bigger, while that in the paddy field and the grassland was much more stable and smaller.(4) In the four kinds of land use types, the dry farmland and the paddy field had higher runoff volume of nitrogen. Compared with the woodland and the grassland, the runoff volume of TN and soluble nitrogen was less subjected to the rainfall runoff. The runoff volume of TN in the dry farmland and paddy field presented bigger range ability with rainfall runoff, while that in the woodland and grassland was much more stable and smaller. Besides, the average concentration of TN runoff in the four kinds of land use types ranked as dry farmland>paddy field>grassland>the woodland. 5.Calculation for the Absolute Emissions Analysis on the Evolutionary Characteristics of the Pollutant Spatial-temporal Pattern in the Yinma River BasinThe absolute emission load of pollutants of the 13 districts and counties in the Yinma River basin and the equivalent standard on land area, the equivalent standard on agricultural product and the equivalent standard on population were calculated, and th e evolutionary features of the pollutants in space and time were analyzed. 6. Reasonable Pollution Control Measures Proposed Based on Current Pollution Situation and Local Conditions... |
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