【作者】 丁园圆；

【导师】 缪启龙； 沈润平；

【作者基本信息】 南京信息工程大学 ， 气候系统与全球变化， 2009， 博士

【摘要】 本文以江苏省仪征市(北亚热带)与江西省余江县(中亚热带)作为研究区域。采用野外调查和室内分析测试,定点研究和区域分析数据,利用地统计学分析和GIS空间建模技术,分析了不同县域内土壤性质的时空变异特征、分布状况及成因;研究了县域农田生态系统表观氮素平衡状况;建立了县域农田潜在可溶出氮模型,并开展了县域尺度上的土壤潜在可溶出氮模拟和验证研究;最后开展了农田生态系统氮素潜在环境风险评价的研究,为我国农田养分科学管理提供理论指导和决策依据。主要的论文结论如下:1)在不同时期的区域研究结果中,仪征市与余江县土壤有机质、全氮、pH值的空间分布大都表现为强烈的或中等空间自相关性,说明受区域性因素影响较大,在2001年余江县全氮和pH值的空间分布表现为弱空间相关性,空间渐变性规律较差,说明受人为因素影响较大。在仪征市,三个时期的土壤有机质、全氮及两个时期的土壤pH值(1984、2000年)在空间分布上的总体趋势是由西北向东南递增,2004年的pH值呈现为中间的小块斑状值低于周边地区;在余江县,1985年的土壤有机质和全氮含量空间分布比较单一;1998和2001年的土壤有机质和全氮空间分布呈中间低南北高的趋势;三个时期的土壤pH值的空间分布规律性较差。总的来说,1984-2004年仪征市的土壤有机质、全氮变化率在大部分地区呈增加趋势,pH值的变化率在研究区域的北部以增加为主,南部沿江地区呈降低趋势。余江县1985-2001年土壤有机质、全氮变化率均有不同程度的增加与降低,增加的区域都主要分布在研究区域的南部和北部的丘陵,pH值的变化率在大部分地区以降低为主。2)农田表观氮素单位面积耕地年平均收入、支出与盈余量的最大值分别位于仪征市东南角沿江区域的朴席镇和余江县河谷平原的邓埠镇;仪征市与余江县在2000-2005年的表观氮素平衡都处于增长趋势,且增长比较平缓。仪征市6年的表观氮素盈余量大于余江县的盈余量。余江县的农田表观氮素盈余量小于余江县的氮素支出量,而仪征市的氮素盈余量大于仪征市的氮素支出量,说明仪征市农田生态系统中积累了过多的氮素,对环境有更大的潜在风险。3)综合利用气象要素模型与NLEAP矿化模型,与表观氮素模型相耦合,建立了土壤潜在可溶出氮模型,选择适用于我国自然条件下的参数方案,以旱地与水田的氮素循环为研究对象,模拟了县域尺度上的农田生态系统的土壤潜在可溶出氮量,并进行了相关验证。结果表明:以水田为主的余江县有机质年平均矿化率低于主要以水田旱地轮作的仪征市,仪征市的水田有机质矿化量小于仪征市旱地有机质矿化量。潜在可溶出氮的结果中,仪征市土壤潜在可溶出氮含量的高值区集中在东南部沿江平原的朴席镇;余江县可溶出氮含量的高值区集中在西南部丘陵岗地的杨溪乡和位于河谷平原的邓埠镇。两个区域的潜在可溶出氮高值区都主要聚集在经济发达的中心城镇及周边城镇。4)从农田氮素损失的三个主要途径(径流损失、淋溶损失、气态损失)入手,筛选出影响氮素盈余的主要因素,通过层次分析法确定影响因素权重,构建氮素潜在环境风险评价模型,并且提出了在表观氮素盈余量控制下的潜在风险评价法。从风险等级来看,仪征农田氮素潜在环境风险以潜在风险为主,低风险区主要位于仪征西南部,潜在风险区主要位于仪征西部、中部、南部镇及东部的部分地区,高风险区主要位于仪征北部以及东南部。余江农田氮素潜在环境风险以低风险为主,风险的分布趋势是东北、西南高,中部低。从土地利用类型来看,水田的氮素损失潜在风险大于旱地。更多还原

【Abstract】 This paper took Yizheng City,Jiangsu Province and Yujiang County,Jiangxi Province as the case study areas,by using field survey data and laboratory analysis test,locational research and datas of regional study,combined with geostatistic analysis and spatial modeling technology of GIS,the temporal and spatial variability of soil properties,distribution and genesis in different areas were analyzed;and the regional agro-ecosystem apparent nitrogen balance were caculated. Then a regional agricultural soil potential soluble nitrogen model was introduced and verified, which simulated the regional scale of the soil potential soluble nitrogen;Finally the field ecosystem nitrogen potential environmental risk assessment studies were carried out.Results can improve decision-making for application of agricultural nutrients in China.The major conclusions of this study are as fllowed:1)At different times the spatial distribution of soil organic matter(SOM),total nitrogen(TN), soil pH in Yizheng City and Yujiang County had the performance of strong or medium spatial autocorrelation,showing that was affected by regional factors.In 2001 the spatial variability of pH and TN in Yujiang County showed weak spatial correlation,which illustrates a greater impact by human factors.In Yizheng City,the spatial distribution of SOM,TN in three periods and soil pH in 1984 and 2000 tend to is increased from northwest to southeast,and pH in 2004 showed low values in the central part with a small blocks.For Yujiang County,SOM,TN content had a single spatial distribution in 1985;and in 1998 and 2001,the spatial distribution of SOM,TN had a trend of low in middle and high in north-south part;the spatial distribution of soil pH had gradient poor law in all three periods.Totally,SOM,TN increased in most regions during 1984 to 2004 in Yizheng.The soil pH value mainly increased in the northern part,and decreased in southern areas along the river.The SOM and TN in Yujiang County during 1985-2001 are mainly increased in the southern and northern hills regions,soil pH values descresed in most regions.2)The maximum value of the average annual input,output and surplus apparent of nitrogen for cultivated land appeared in Puxi Town located in the southeast corner region along the Yangtze River in Yizheng and Dengbu Town located in river valley plain in Yujiang County.Apparent nitrogen surplus of yizheng City and Yujiang County had a increasing trend during 2000-2005 with a low increase rate.The surplus of the apparent nitrogen of Yizheng City was greater than Yujiang County.The surplus of farmland apparent nitrogen is less than the output in Yujiang County,while it was larger than nitrogen output in Yizheng.This showed that nitrogen accumulated at a high extent in the agro-ecosystems in Yizheng,which has a high potentially riskto the environment.3)By coupling meteorological factors Mode,NLEAP mineralization model,and the apparent nitrogen balance model,a soil potential soluble nitrogen(SPSN) simulation model was established to simulate the nitrogen surplus risk at the regional scale.The simulation results showed that average annual mineralization rate of soil organic matter(SOM) in Yujiang County(mainly in paddy fields) was less than Yizheng City(with a main rotation of rice-wheat),the mineralization of SOM in paddy fields in Yizheng was less than uplands.According to the results by SPSN,the high-value areas of the SPSN content was located in Puxi town on the south-eastern plains along the river in Yizheng city;while Yangxi town located in the southwestern hills and Dengbu Town located in the Tang valley plain in Yujiang county,where were the center town or surrounding towns with developed economies.4)The major factors affecting three main ways of nitrogen losses from farm(run-off losses, leaching losses,gaseous losses) was selected.By using the analytic hierarchy process,the weight factors was decided and the potential environmental risk assessment model based on apparent nitrogen surplus.The evaluation result showed that farmland nitrogen surplus in Yizheng had an a average potential risks.Low-risk areas were mainly located in the southwestern part of Yizheng, high-risk areas are mainly located in the north and the south-east part of Yizheng.The farmland nitrogen surplus in Yujiang was averaged at a lower risk level.The high risk region was in the northeast and southwest part,and the low risk region was in the central part of Yujiang.For the land-use type,the nitrogen loss potential risk of the paddy fields was greater than the uplands.更多还原