【摘要】 通过研究汉江上游金水河流域土壤无机物风化与有机物分解代谢相互关系,揭示研究流域尺度范围内常量元素的生物地球化学循环和空间分异的主驱动因子。通过野外调查与取样、实验室样品检测和空间模拟分析,得到以下的研究结果:(1)金水河流域的土壤风化已基本完成早期阶段的去Ca,Na风化阶段,进入K风化阶段;(2)土壤风化内外因素(如,土壤母质、矿物结构、温度、降水、风和重力等)作用下形成了明显的空间差异,流域内属于典型的林下有机质积聚过程,土壤矿物中的硅酸盐矿物风化分解和淋溶作用较强;(3)土地利用方式改变了土壤有机质分布模式,不合理的人类活动造成农田耕作层和森林枯枝落叶层的有机质减少,土壤腐殖酸的减少影响土壤矿物风化和元素地球化学行为,对农业持续发展形成负面的影响。流域作为南水北调中线水源地,保护森林植被及枯枝落叶层对土壤涵养水分有着重要意义。更多还原

【Abstract】 The purpose of this study is to investigate geochemical process and driving forces of soil major chemical elements in the forest-dominated Jinshui River basin,tributary of the upper Hanjiang River.We carry out investigations on soil major chemical elements distribution and transport patterns and driving forces by integrated analysis of natural environmental factors and human activities.In order to achieve these goals,we further employ efficient approaches including field investigation,laboratory testing and GIS spatial simulation.Through this research work,following findings are achieved.Firstly,general soil weathering process of Jinshui River Basin basically evolves from Ca,Na stages to K stage.Ca,Na decreased rapidly,and silicate weathering process evolved gradually.Major ions of water are subject to carbonate dissolution,about 2 / 3 of the soil in the basin are alkaline(pH>7) which provide good condition for mineralization of organic nitrogen.Chemical index of alteration(CIA) gradually increase from south to north,initially decrease from east to west and increase eventually.Predominant major elements in the upper stratum of soil are oxides of Si,Al,Fe and Ca,which account for about 78.1% of the total.Secondly,specific soil weathering process differs in spatial patterns and elements transport which is driven by integrated interior forces(e.g.,mineral materials) and external forces(e.g.,temperature,precipitation,wind and the gravity).Original mineral materials are changed into soils with different physical properties(soil texture,mechanical composition) and chemical components(organic matter).Upstream original mineral materials have been transported,accumulated and deposited in the downstream,which are driven by forces of gravity,water transport,glacial effects,and wind.Key ecological factors of plant growth change greatly which are caused by integrated environmental effects such as climatic conditions,sunlight,nutrients and soil biological characteristics.Organic matters accumulate in forest covered belts of Jinshui River while inorganic weathering processes are dominated by decomposition and eluviation of silicate minerals.In the vertical section,within all vegetation types,soil moisture storage capacity and saturation decrease with an increase in depth.Forest soil has better conditions of physical properties and chemical characteristics than those of wasteland and farmland.Mixed coniferous soil reserves the most water than other vegetation types,followed by coniferous forest,chestnut forest and shrub.Thirdly,land use and cover is one of key contributors to determine geochemical patterns of soil organic matters.Land use and cover types greatly impact on volumes of standing deadwood,particulate organic carbon content and Na / K value.Soil particulate organic carbon and Na / K are in good correlation,especially in dry land and bamboo areas.Intensity of mineral weathering process decreases with the decrease of biomass which follows the sequences,dry land> bamboo> paddy soil> shrub> coniferous forest> mixed forest> deciduous forest.Improper human activities decreased soil organic matters,and thus had negative impacts on agriculture.However,it helps to prevent the loss of N,P if effective countermeasures are adopted to develop a vegetation buffer zone along riversides,especially in residential areas.The overall investigation of this study suggests that protection of forestry ecosystem and proper human activities are important for improvement of water quality and soil erosion.更多还原