高集约化农业土地利用的环境风险管理体系研究

发布时间：2018-05-04 15:31

本文选题：土地利用系统 + 环境风险　；参考：《中国农业大学》2017年博士论文

【摘要】：在中国经济快速发展、人口刚性增长、耕地面积持续减少的背景下,农业集约化程度不断提高。农药和化肥的大量使用极大地提高了作物产量,但农业化学品的大量投入、种养殖有机废弃物随意处理排放等也导致土壤和环境质量的下降,农业活动导致的环境污染呈现加剧趋势。特别是在以高土地利用强度、大量农业化学物质投入为特征的高集约化农区,农业土地利用面临着保障粮食安全和生态环境安全的双重挑战,如何保障粮食安全和农村经济持续发展的同时,减少或控制农业土地利用的环境风险是协调农业生产发展与环境保护矛盾,实现中国农业农村持续健康发展面临的一项艰巨而紧迫的任务。本文从土地利用系统的角度出发,综合运用系统科学、人地关系理论、可持续发展理论、风险管理理论、农户行为选择理论、可持续农户生计理论等相关理论和方法,对高集约化农业土地利用的环境风险管理的理论与应用进行系统研究,选择案例区从农业土地利用环境风险的诊断与识别、风险评价、风险制图和风险管控等方面建立农业土地利用的风险管理体系,以期实现对农业土地利用环境风险的管控。主要研究结论如下:1.中国农业土地利用的环境风险评价在全面分析中国农业土地利用系统的基础上,识别主要的环境风险来源,分别对化肥、农药、农膜施用以及秸秆处理等农业活动带来的非点源污染来评估中国当前农业土地利用方式对环境的影响。结果表明:中国农业土地(主要指耕地)的氮磷侵蚀流失量分别为144万t和6万t,单位耕地面积的N、P流失强度分别为13.3 kg/hm2和0.89 kg/hm2,中国东部地区的单位耕地氮磷排放强度较高;全年7种常见农药有效成分流失量达到30t,除草剂乙草胺对总农药流失量的贡献达到77.65%,东北地区的农药流失强度最高,但东部和南部地区的农药施用环境风险较高;全国农膜残留率为17.97%,残留量大,大量的农膜残留还会造成土壤中邻苯二甲酸酯类物质(PAEs)含量超标,污染土壤;农作物秸秆焚烧量占到全国秸秆产生量的13.07%,秸秆焚烧在北方主要集中在4-7月,而在南方地区则集中在10-11月。总体上,这些非点源污染在空间分布上存在一定的空间相关性。2.区域农业土地利用系统的环境风险识别、评价及制图以中国粮食主产区之一的洞庭湖区为研究区,选取湖南省桃江县为案例区,在区域土地利用系统分析的基础上,识别主要的环境风险来源,对区域农业土地利用系统的环境风险进行评估,探讨了区域农业土地利用环境风险的制图方法。结果表明:土壤重金属污染、水体富营养化是桃江县农业土地利用的主要环境风险,另外农药和农膜施用以及秸秆焚烧等在风险评价中也应该重点关注;桃江县的土壤N/P侵蚀流失、农药流失及施用风险、作物秸秆焚、土壤重金属污染等风险程度较高,土壤农膜残留风险较小,各类环境风险空间分布不均;从综合风险的角度来看,风险因子和风险受体脆弱性分布具有较强且趋同的地域特征,加大了人、水体等风险受体的暴露风险,应该加强重点区域管控。3.区域农业土地利用的环境风险管控在大量农户调研、实验数据分析的基础上,分别从农户生计与土地利用行为分析、土地流转政策、农业土地安全利用分区及田间管控等三个方面探讨区域农业土地利用的管控体系。结果表明:桃江县的农户生计正在发生变化,理解农户生计变化特征,引导农户在生计变化过程中优化土地投入可以降低区域农业土地利用环境风险;尽管产量有所降低,但研究区土地流转和规模经营有利于农户减少农药、化肥等物质投入,在土地流转面积不断增加的情况下,将明显减少区域农业土地利用的环境风险,决策者应该采取行动合理引导农户进行土地流转;由于土壤重金属难于治理,依据土壤-作物重金属协同风险对区域农业土地利用进行综合管理,可以实现对区域土壤重金属污染的风险管控。
[Abstract]:In the context of rapid economic development, rigid population growth and continuous reduction of cultivated land area, the degree of agricultural intensification has been increased continuously. The large amount of pesticide and chemical fertilizer use greatly improved the crop yield, but the large input of agricultural chemicals and the free disposal of the organic wastes of the species also led to the decline of the soil and environmental quality. The environmental pollution caused by agricultural activities is becoming more and more serious. Especially in the high intensive farming area characterized by high land use intensity and a large amount of agricultural chemicals input, agricultural land use faces the dual challenge of ensuring food security and ecological environment security. Or controlling the environmental risk of agricultural land use is a difficult and urgent task to coordinate the contradiction between the development of agricultural production and environmental protection, and to realize the sustainable and healthy development of agricultural rural areas in China. From the perspective of land use system, this paper comprehensively uses system science, human land relationship theory, sustainable development theory and risk management theory. On the basis of the theory and methods of farmers' behavior selection theory and sustainable farmers' livelihood theory, the theory and application of environmental risk management of high intensive agricultural land use are systematically studied, and the case area is selected from the aspects of agricultural land use environmental risk diagnosis and identification, risk assessment, risk mapping, risk management and so on. The main conclusions are as follows: 1. the environmental risk assessment of agricultural land use in China is based on the comprehensive analysis of the agricultural land use system in China and identifies the main sources of environmental risk, and the application of chemical fertilizers, pesticides, and agricultural membranes, and Non point source pollution caused by agricultural activities such as straw treatment to assess the impact of current agricultural land use patterns on the environment in China. The results show that the loss of nitrogen and phosphorus erosion in agricultural land (mainly cultivated land) is 1 million 440 thousand T and 60 thousand T, respectively, N of unit land area, and the loss intensity of P is 13.3 kg/hm2 and 0.89 kg/hm2, respectively, in eastern China The intensity of nitrogen and phosphorus discharge in the unit cultivated land is high, and the loss of 7 common pesticides is up to 30t in the whole year. The contribution of herbicide acetochlor to total pesticide loss is 77.65%, and the intensity of pesticide loss in the northeast is the highest, but the environmental wind risk is higher in the eastern and southern regions, and the residual rate of the national agricultural membrane is 17.97% and the residual amount is large. A large number of residual membrane residues also cause the excess of phthalic acid esters (PAEs) content in soil, contaminated soil, crop straw incineration accounted for 13.07% of the national straw production, straw burning in the North mainly in 4-7 months, and in the southern region of 10-11 months. In general, these non-point sources of pollution in the spatial distribution of the existence of two. The environmental risk identification, evaluation and mapping of a certain spatial correlation.2. regional agricultural land use system are taken as the research area in Dongting Lake area, one of the main grain producing areas of China, and the Taojiang County of Hunan province is selected as the case area. On the basis of the regional land use system analysis, the main environmental risk sources are identified and the regional agricultural land use system is used. The environmental risk is evaluated and the mapping method of regional agricultural land use risk is discussed. The results show that heavy metal pollution and eutrophication are the main environmental risks of agricultural land use in Taojiang county. In addition, the application of pesticides and agricultural film and straw burning should also focus on the risk assessment; Taojiang County The soil N/P erosion and loss, pesticide loss and application risk, crop straw burning, soil heavy metal pollution and other risks are higher, the residual risk of soil membrane remains small, and the spatial distribution of various environmental risks is uneven. From the perspective of comprehensive risk, the risk factor and risk receptor vulnerability distribution have strong and convergent regional characteristics and increase people. The exposure risk of water body and other risk receptors should strengthen the environmental risk management of agricultural land use in the.3. region of key areas. On the basis of a large number of farmers' investigation and analysis of experimental data, three aspects of farmers' livelihood and land use behavior analysis, land circulation policy, agricultural land safety utilization zoning and field control and control should be made respectively. The management and control system of regional agricultural land use is discussed. The results show that the livelihoods of farmers in Taojiang county are changing, understanding the characteristics of farmers' livelihood change and guiding farmers to reduce the risk of regional agricultural land use environment by optimizing the land input during the change of livelihoods. It is beneficial for farmers to reduce the investment of pesticides and chemical fertilizers. Under the condition of increasing land circulation area, it will obviously reduce the environmental risk of agricultural land use in the region. The decision-makers should take action to guide farmers to carry on the land transfer reasonably; because the soil heavy metals are difficult to govern, the soil crop heavy metals can cooperate with the risk in the area. Integrated management of agricultural land use can achieve the risk management and control of heavy metal pollution in regional soils.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：F321.1

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