南陵—泾县国家商品粮基地农田区土壤特征元素分布差异性及潜在生态效应

发布时间：2017-12-27 19:40

本文关键词：南陵—泾县国家商品粮基地农田区土壤特征元素分布差异性及潜在生态效应　出处：《中国地质科学院》2017年博士论文　论文类型：学位论文

【摘要】：南陵-泾县国家商品粮基地是我国著名的"南陵大米"产地、"国家优质米基地"和"国家商品粮基地",该区特色农业发展亟需深入认识农田表层土壤有益/重金属(特征)元素分布特征、差异性和潜在生态效应。本研究以安徽省南陵-泾县国家重要商品粮基地分布区为重点研究区,围绕"农田区表层土壤中有益/重金属元素的分区特征、差异性及形成机制"关键科学问题,侧重"土壤有益/重金属(特征)元素或组份背景值识别与确定"、"农田区水土环境系统分区单元识别与划分"、"不同分区表层土壤中有益/重金属元素或组份分布差异特征与成因"和"农田表层土壤中重金属元素潜在生态效应与对策"研究,在1:5万农田区水文地质与土地质量地球化学综合调查基础上,通过增设纵-横剖面加密采样点、垂向剖面增加采样密度等实物工作量和专项试验及综合研究,取得如下突破性进展和新认识。(1)根据地貌的单元特征、地表水系的流域特征和地下水系统的分区特征,同时,重视土地利用现状和农作物种植类型影响,将研究区划分为5个分区单元,首次查明和确定了各分区32种元素或组份的土壤地球化学背景值,建立了本次研究的各分区环境基准值,奠定了该商品粮基地农田区表层土壤有益/重金属异常状况的识别与研判科学基础。(2)基于半方差变异函数理论,论证了全区541组土壤样品及数据具有变异性较小的可靠性,并阐明研究区表层土壤中有益/重金属元素分布差异性的成因。较小的块金值反映出有益元素、重金属等空间区域化变量由于误差和随机因素造成的变异性较小;块金值与基台值之比揭示了元素自相关程度。研究结果表明,在"南陵-泾县商品粮基地"农田,除有机质、N、有效Mn外的大部分有益元素和全部重金属元素均表现为"中等-强"的空间自相关性;该区表层土壤中各类特征元素空间分布差异性,是气候、母质、地貌和土壤类型等结构性因素,以及随机性人类活动共同影响结果,自然因素为主导,局部农田区人类活动起主要作用,包括上游区矿产资源开发、农田区大量施用除草剂、农药和化肥等影响。(3)采用地质累积指数法,揭示了南陵-泾县国家商品粮基地表层土壤中9种重金属元素分区特征及其对土地质量潜在风险影响程度和分布差异性。研究结果表明:Ⅰ分区呈现Hg对农田土地质量影响"轻度-中等"风险范围最大,仅有13.7%的区域未受到影响;65.3%的农田区受到Cd的影响,14.5%的农田区受到As的影响。Ⅱ分区95%以上的区域,表层土壤未受到重金属潜在风险影响。在Ⅲ分区,表层土壤中Hg地质累积指数的最大值为3.38,是该商品粮基地分布区的最大地质累积指数,影响区域占Ⅲ分区面积的90%以上,其中"轻度-中等"影响范围占73.8%。ⅣV分区的表层土壤中Hg、Cd影响最为显著,局部农田Cd对土地质量的潜在风险影响呈"强"程度,Hg呈"中等-强"程度和As、Mn呈"中等"程度。在V分区,As、Hg和Cd对土地质量的潜在风险影响比较明显,受"中等"程度的As潜在风险影响区域占18%,超过30%的区域受Hg、Cd潜在风险影响达"中等"及以上程度。(4)采用潜在生态风险指数法,阐明了南陵-泾县国家商品粮基地的不同分区表层土壤重金属对土地质量潜在生态风险影响的分区特征和分布差异性。研究结果表明:在5个研究分区中,As、Pb、Cr、Cu、Zn、Fe和Mn的潜在生态风险指数介于0.74～23.86,对农田表层土壤的潜在生态风险影响"轻微",只有Cd、Hg和As潜在生态风险影响比较明显,其中Hg潜在生态风险影响"强"的区域占70%以上,Cd以"中等"影响程度为主。在Ⅰ分区,Cd潜在生态风险影响"中等"的区域占75%;在V分区,30%区域受Cd潜在生态风险影响为"强-极强"程度。在Ⅳ、Ⅴ分区,As潜在生态风险影响"中等"区域占该研究区面积的10%以上;而Ⅰ、Ⅱ分区和Ⅲ分区,基本不存在As的潜在生态风险影响。(5)针对性提出:在南陵-泾县国家商品粮基地需要进一步加强农田区表层土壤中Hg分布状况、来源和变化特征调查,尽快开展1:1万土地质量地球化学专项调查和异常查证,以及防控农田区表层土壤中Hg潜在生态风险关键技术和对策研究;应加强Ⅰ、Ⅴ分区表层土壤中Cd的潜在生态风险成因、主要来源和Ⅳ、Ⅴ分区As的潜在生态风险影响趋势和影响范围核查,尽快形成有利于当地绿色农业发展技术咨询建议报告,服务地方经济社会可持续发展。
[Abstract]:Nanling - Jingxian County national commodity grain base in China is the famous "Nanling rice" origin, "national high quality rice base" and "national commodity grain base, the characteristics of agricultural development needs in-depth understanding of the farmland soil heavy metal elements (good / characteristic) distribution, diversity and potential ecological effects. In this study, Anhui Province, Nanling Jingxian County an important national commodity grain base region as the main study area, around the "key scientific problems in surface soil of farmland area in good / partition characteristics of heavy metal elements, the differences and the formation mechanism, focusing on" beneficial soil / heavy metals (features) elements or components identification and determination of background value "" the farmland soil and water environment system partition unit identification and classification, different partitions in the surface soil beneficial / heavy metal elements or components distribution characteristics and causes of "and" in the farmland soil heavy metal potential ecological effects and Countermeasures "research in the 1:5 million farmland hydrological and land quality comprehensive investigation of the chemical basis of the Earth last, through the addition of longitudinal cross section encryption sampling point, vertical profile density increased workload and special test and comprehensive research sample, made the following breakthroughs and new understanding. (1) according to the landform unit characteristics, surface water and groundwater system of watershed characteristics zoning characteristics, at the same time, pay attention to the influence of land use status and crop types, the study area was divided into 5 sub units, for the first time to identify and determine the partition of 32 elements or components of the soil geochemical background values, establish the study of the environment of each partition reference value, establishes the commodity grain base of farmland soil heavy metal anomaly recognition / beneficial and judged scientific basis. (2) based on the theory of half variance variogram, the reliability of the 541 groups of soil samples and data in the whole area is proved to be less variability, and the reason for the difference of the distribution of beneficial / heavy metals in the surface soil of the study area is clarified. A small nugget reflects less variability of regional variable beneficial elements and heavy metals due to space error and random factors; nugget value and base value of the element ratio reveals the extent of autocorrelation. The results show that the farmland in the "Nanling - Jingxian County commodity grain base, in addition to most of the useful elements of organic matter, N, Mn outside and all the heavy metals were" moderate spatial autocorrelation - strong "; the spatial distribution characteristics of various elements in the area of differences in surface soil, climate, parent material, topography the soil type and the structural factors, and the randomness of human activities affect the results, as the dominant natural factors, local farmland area of human activities play a major role, including mineral resources development, the upstream region of farmland utilization of herbicides, pesticides and chemical fertilizers and other effects. (3) using the index of geological accumulation, we have revealed the zoning characteristics of 9 heavy metals in surface soil of Nanling Jingxian County national commodity grain base and their influence degree and distribution difference to land quality potential risks. The results showed that: 1. The area of Hg showed the largest "light to medium" risk for farmland quality, and only 13.7% of the area was not affected. 65.3% of the farmland area was affected by Cd, and 14.5% of the farmland area was affected by As. The surface soil is not affected by the potential risk of heavy metals in more than 95% regions. In the third area, the maximum value of Hg geological accumulation index is 3.38, which is the largest geological accumulation index in the distribution area of the commodity grain base. The influence area accounts for more than 90% of the third area area, and the "mild to moderate" influence area accounts for 73.8%. The influence of Hg and Cd in the surface soil of V IV is the most significant. The effect of Cd on the potential risk of land quality is strong. The Hg is moderately strong, and As and Mn are "moderate". In the V partition, As, Hg and Cd have a significant impact on the potential risk of land quality. The area affected by the potential risk of "moderate" As accounts for 18%, and more than 30% of the area is affected by the potential risks of Hg and Cd to "medium" or above. (4) by using the potential ecological risk index method, the zoning characteristics and the distribution difference of the surface soil heavy metals on land quality and potential ecological risk in Nanling Jingxian County national commodity grain base were clarified. The results showed that: in the 5 of the partition, the potential ecological risk index between As, Pb, Cr, Cu, Zn, Fe and Mn from 0.74 to 23.86, the potential ecological risk influence on topsoil minor ", only Cd, Hg and As potential ecological risk effect is obvious, the potential ecological Hg the risk effect of" strong "region accounted for more than 70%, Cd to the" medium "influence mainly. In the I zoning, the potential ecological risk of Cd was 75% in the "medium" area; in the V zoning, the 30% region was affected by the potential ecological risk of Cd as a "strong - strong" degree. In Area IV and V, the potential ecological risk of As is more than 10% of the total area, while there is no potential ecological risk of As. (5) put forward: in Nanling - Jingxian County national commodity grain base to further strengthen the investigation of surface soil in the farmland area Hg distribution, sources and characteristics of 1:1 million land quality geochemical survey and the anomaly investigation carried out as soon as possible, and the prevention and control of farmland soil in surface Hg potential ecological risk key technology and countermeasure research; the potential ecological risk of I, should strengthen the potential ecological risk causes, V partition in surface soil of the main sources of Cd and IV and V partition As trend and the influence scope of verification, as soon as possible formation technology development advice to the local green agricultural industry, local economic and social sustainable development.
【学位授予单位】：中国地质科学院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S153.6

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