| Organic agriculture is currently the least harmful gricultural production method to the ecosystem,animals and people,and is considered to be a better choice between production,ecosystem and biodiversity conservation.In 2002,China began to fully promote the "pollution-free food action plan",and then gradually implemented the formulation of standards for organic products.At present,the water quality requirements for surface water irrigation in domestic organic agricultural production areas are the same as those for the production of ordinary agricultural products.However,with the extensive use of pesticides and fertilizers,the widespread application of planting and breeding additives and the surge of industrial pollution,the types and quantities of pollutants in water bodies continue to increase.It is urgent to establish the evaluation system and standards related to the surface water environment of organic agricultural production areas for irrigation,so as to provide decision-making support for the evaluation of the water environment of organic agricultural production areas.Xing’an League is located in the golden zone of animal and plant growth at 44°14 ’north latitude in the northeast of Inner Mongolia.It has a long history of rice cultivation,abundant water resources,adequate illumination and less industrial pollution.It has natural geographical advantages for the development of organic agriculture.The surface water quality of major rivers in Xing’an League of Inner Mongolia from 2008 to 2019 was investigated and analyzed,and the overall water quality was preliminarily judged by single factor evaluation method and Nemero pollution index method.Based on the AHP analytic hierarchy model,a total of 37 water quality indicators were selected to protect human health,ecological environment and future ecological risk,and a water quality evaluation system for organic agricultural surface water irrigation was established.Refer to the United States,Japan,Korea and China and other countries of agricultural irrigation water and surface water quality standard,the analysis of various index of acute toxicity and chronic toxicity values,in the water quality index of long-term exposure to potential ecological risk is different,the irrigation water quality suitability irrigation area is divided into extremely suitable,suitable,generally regarded as optional area and unsuitable four grades.In interpretation and reference to the domestic related literature and the policies and regulations,on the basis of combination of Xing’an League calendar year water quality trend and the actual water quality,surface water from organic agriculture irrigation water quality evaluation system of 11 main influence water quality parameters of surface water in Xing’an League of Inner Mongolia was selected,organic agricultural irrigation water quality of surface water suitability evaluation of the local standard and the index system was built.Based on the major rivers in Xing’ an League of Inner Mongolia typical monitoring of surface water quality data,using the entropy weight method,assignment and weighted average cross section water quality comprehensive index is calculated,as well as the single factor index of water quality data,by single factor and integrated index combining together the local surface water level has been evaluated and irrigation area.The main conclusions are as follows:(1)The surface water quality of major rivers in the Xing’an League has been stable for a long time,and the concentrations of toxic and harmful pollutants such as organic pollutants are extremely low,all within the safe range.The overall water quality has been stable for a long time between the surface water Ⅰ～Ⅲ class,but some sections’water quality indexes exceeded the standard.The initial evaluation results of single factor evaluation method and Nemero pollution index method showed that DO,NH3-N and TP were the main factors exceeding the standard,and the main sections exceeding the standard were Silihen and Baliba sections of Taoer River,Jiajiajie section of Guiliu River and Gaoliban section of Huolin River.(2)Weight results show that the surface water in Xing’an League pH weight value is the smallest,made the least effect on water quality,the DO,Pb two index weights made the largest impact on the overall water quality,the NH3-N and TP is the main reason of the indexes exceed the agricultural non-point source pollution and industrial pollution,from the evaluation results of the evaluation system of evaluation result is consistent with the actual water quality situation in Xing’ an League.(3)Among the 6 rivers and 1 reservoir,the water quality of Jiaoliu River is the best,which is kept between Ⅱ～Ⅲ category of surface water all the year round,is an extremely suitable area for development in the evaluation system of organic agricultural irrigation water quality.The water quality of Chuoer River and Chalsen Reservoir is the second,which keeps in the III category of surface water all year round,and reaches the level standard of suitable development area in the organic agricultural irrigation water quality evaluation system.The water quality of Huolin River and Guiliu River is relatively poor,and the water quality of Taoer River is the worst,which has not reached the III standard for surface water for 2 years in the past 11 years,and is mainly polluted by DO,NH3-N and TP.After removing or weakening the influence of N and P on water quality rating results,the water quality of Guiliu River and Huolin River is good,basically meeting the water quality demand of organic agricultural irrigation.Due to the inactivity of microorganisms and the weak ability to decompose organic pollutants in these three rivers,CODMn exceeded the standard in the background value of natural water quality in the rivers,which should be paid more attention to.(4)Among these sections we can found,①The overall water quality flows through the Tao’er River below the city of Ulanhot--Silihen and Baliba sections were the worst,with the comprehensive index of 41.435 and 41.357,respectively.The single factors lower than the suitable standard were NH3-N and TP,which were classified as the unsuitable area for the development of organic agriculture.②The comprehensive indexes of Jiajie section in Huolin River and Gaoliban section in Guiliu River were 47.706 and 44.796,respectively.The single factor results of some indexes were lower than the suitable standard,been classified as the alternative development area of general suitable area for organic agriculture.③The comprehensive indexes of the three sections at the west entrance,east entrance and exit of the Chalsen Reservoir were 51.885,53.381 and 54.132,respectively.The single factor lower than the suitable standard was CODMn,which was classified as the alternative development area of general suitable area for organic agriculture.④Baoquan section of Jiaoliu River and Chuoer mouth section of Chuoer River had the best water quality,with the comprehensive index of 56.274 and 53.971,respectively.The single factor evaluation results of all indexes were above the suitable standard,and the region was classified as an extremely suitable area for the development of organic agriculture.⑤The water quality in Dashan mine section of Halaha River is good,but it is not suitable for developing organic agriculture due to geographical factors.(5)According to the different suitability degree of surface water for organic agriculture irrigation,according to the theory of agricultural regionalization and the concept of land planning,the six cities(banner)in Xing’an League were divided into three main functional areas:organic agriculture,industrial industry and ecological landscape.As well as agricultural-urban transition area,urban-ecological transition area and ecological-urban transition area three transition areas.Organic agriculture development core area(Middium Keyou Banner-Zhalaite Banner)aims to improve soil fertility and biological diversity of organic agriculture development,to realize the continuous and intensive use of organic agricultural land.Industrial Industrial Development Core Zone(Ulanhot City)takes innovation as the enterprise orientation,promotes cleaner production and improves the ecological quality of the city.The core area of ecological landscape development(Arshan City)makes full use of its natural advantages,vigorously develops the leisure tourism industry,and ensures the excellent development of the ecological environment. |
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