Investigation Of Agricultural Non-Point Source Pollution In Chongqing Section Of The Three Gorges Based On Pressure-state-response

The Three Gorges reservoir area was an important reginon that was considered as agricultural eco-economic in Chongqing and eco-environment construction in China. Its eco-environmental quality not only related to Three Gorges engineering but also development of economy, ecology and society. Recenty, the agricultural production of Three Gorges reservoir area had been largely developed; rural economic had been largely improved. But the agricultural production and living model character as non-sustainable development and high consumption extensive exist. The environmental problem of agricultural recourses, espeicallly, agricultural non-point source pollution (ANPSP) had been restricted agricultural sustainable development as an important factor and aroused nation and local governments high regard. The research of ANPSP of Three Gorges reservoir area was relatively more. But the analysis of ANPSP in Three Gorges reservoir area by pressure-state-response model (P-S-R) was just first.Firstly, the P-S-R model was constructed on the systematical researches of ANPSP. Subsequently, the discharge amounts of COD, BOD₅, total nitrogen (TN) and total phosphor (TP) was accounted by the list analysis on the scale of districts (counties) from the 7 sources of ANPSP such as chemical inorganic fertilizers, organic fertilizers, crops straw, stockbreeding, domestic sewage, domestic wastes and soil erosion, the degree loading of ANPSP was evaluated. The case of 21 districts (counties) was used to determine the priority pollutants, the priority pollution source, the priority affecting factors, the priority contaminated area and the character space-time of ANPSP in Chongqing section of the Three Gorges reservoir area (CSTG). Then, the direction of ANPSP was forecasted by using the gray model, the environmental capacity and reduction of ANPSP was accounted basic on gray model. development degree, correspond degree, handicap degree and coupling medal of ANPSP loading was discussed form the circular agriculture attached by biogas. Finally, the response of reduced NPSP from developing door biogas was discussed mainly on the case of Wangjiagou small valley in Fuling District. Thereby scientific basis was offered to establishing ANPSP prevention and protecting Three Gorges reservoir.The P-S-R model was introduced by systematical researches on ANPSP, in which the discharge amount and its coefficient of ANPSP could be regard as "pressure", the change of water quality could be regard as "state", and feed backed human activity could be regard as "response". Pollution exoteric index system and practice index system in the P-S-R model of ANPSP was designed basing on this model.The discharge amounts of COD, BOD₅, total nitrogen (TN) and total phosphor (TP) was accounted by the list analysis on the scale of districts (counties) from the 7 sources of ANPSP such as chemical inorganic fertilizers, organic fertilizers, crops straw, stockbreeding, domestic sewage, domestic wastes and soil erosion, the absolute discharge amount of COD, BOD₅, TN and TP from ANPSP were 266.4, 107.1, 80.7, 15.2 thousand tons per year, respectively. Thereinto, the let quantity of COD exceeds the summation of industry and living of current-year in CSTG.The discharge amount in equivalent standard for pollutants source that accounted on the scale of districts (counties) from the 7 sources of ANPSP such as chemical inorganic fertilizers, organic fertilizers, crops straw, stockbreeding, domestic sewage, domestic wastes and soil erosion were 53555, 12739, 6492, 120325, 11086, 917, 1672t/α, respectively. The discharge amount of aquiculture was furthest, secondly were chemical inorganic fertilizers, organic fertilizers and domestic sewage.The comparatively discharge amount in equivalent standard for country area of CSTG at 2007 was 5.01t/km, Thereinto, The let quantity of planting, breeding, living, and spontaneousness erosion were 1.91, 2.74, 0.32, 0.03t/km, respectively. Indicating ANPSP was mainly brought by stockbreeding and farmland planting.The let concentration of COD, BOD₅, TN, TP was accounted base on them absolutely let quantity of CSTG, thereout, average concentration of COD, BOD₅, TN, TP leaded by ANPSP in CSTG were 10.04, 5.44, 2.98, 0.67mg/L, respectively.The bad pollution water quality of CSTG were Shapingba, Dadukou, Banan, Jiangbei and Jiangjing that placed the Three Gorges reservoir area upriver, Wushang, Shizhu, Wuxi, Fengjie, Kaixian, placed the Three Gorges reservoir area lower reaches (core area), were polluted rather ethereal, set pair analysis indicted that the water quality of Wushang, Shizhu, Wuxi, Fengjie were II level in CSTG, The rest of 15 countries were V level.Mainly pollutant of ANPSP in CSTG were TP, TN, contribution rate were 40.08% and 36.83%; mainly pollution sources were stockbreeding and chemical inorganic fertilizers, contribution rate were 58.21% and 27.243%; Mainly influence factor was total Agro-production value, was more than 90%; Mainly pollution areas were Dadukou, Shapingba, Yubei, Jiangbei and Zhongxian; mainly influence factor was agro-production value. Indicating the let quantity of COD, BOD₅, TN, TP produced from agro-production activity. The couping analysis of pollutant and pollution sources showed that stockbreeding provided COD, was mainly pollution sources, other sources provided BOD₅, TN, TP.Using squares of deviation, Clustering analysis, was adopted for analyzing the P-S-R of ANPSP in CSTG, helped to classify guidance of ANPSP. Preventing ANPSP must defend the "pressure" as well as fathered the "state" of pollution. Only seeking both temporary and permanent solutions and classifying guidance, Can radically prefabricated the exasperate trend of ANPSP.The gray model of ANPSP, forecasted concentration of COD, BOD₅, TN, TP leaded by NPSP were 268533, 95859, 52889, 9726t/α, was established base on the station of NPSP in CSTG. Moreover, those pollution was distributed every areas, every polluted sources, every pollutions, and so on. Circular Agriculture, its obstacle degree has a markedly correlation with press index of NPSP, could profoundly affected ANPSP. Obstacle degree has a direct proportion with the risk of ANPSP, that is to see only conquered the factor of agricultural obstacle degree, can reduced the loading of ANPSP.In the circular agricultural factors, dominant factor delegated the dejecta bearing index of stockbreeding, the area of planting and average income of people's living, hereinto dejecta bearing index showed restrain, but the area of planting and average income accelerated aggravate of ANPSP.Circular agricultural dominant by biogas could controlled 7 sources of ANPSP such as chemical inorganic fertilizers, organic fertilizers, crops straw, stockbreeding, domestic sewage, domestic wastes and soil erosion, had immediacy effect as well as indirectly, had accelerate effect as well as restraint. An biogas of 8-10 m³ could reduced COD, BOD₅, TN, TP to water, were 230.65, 46.87, 38.00kg, T11.84kg, respectively.Taking Wangjiagou small valley in the Fuling District for example, it showed that the absolute discharge amount of COD, BOD₅, TN and TP from this ANPSP were 12099, 6414, 1780, 327kg, mainly pollutant were TN and TP; mainly polluted sources were chemical inorganic fertilizers, crops straw, stockbreeding which discharge average concentration of COD, BOD₅, TN and TP were 22.23, 11.44, 3.15, 0.58mg/L, it had not markedly difference with measure. Indicting that account of loading ANPSP had a better consistent with fact measure. In order to make pollution emission below standard and taking waterenvironmental capacity into consideration, Wangjiagou small valley need to built 32 biogas that using ratio reached 49.2%."P-S-R" model had been firstly used to analysis ANPSP, pollution exoteric index system and practice index system in the P-S-R model of ANPSP was established basing on this model.Though feature of this paper consisted: (1) "P-S-R" model had been firstly used to analysis ANPSP, pollution exoteric index system and practice index system in the P-S-R model of ANPSP was established basing on this model. (2) The forecast of loading ANPSP based on the list had been integrated with fact measure to quantitated Ratio of loading ANPSP. (3) Biogas and circular agricultural affecting response of ANPSP reduction was discussed form quantification, parameter of door biogas responding form ANPSP reduction was established. But a majority of "area" data come from various related statistical annual reports and "dot"data come form sampling intermigration and interview, for the future, all data from account should be sampling inspected, "river load ratio" of pollutant should be optimized by release kinetics.