导　　师： 傅瓦利

学科专业： G0501

授予学位： 硕士

作　　者： ;

机构地区： 西南大学

摘　　要： 三峡水利枢纽工程是目前世界最大的水电工程,为了保证三峡水库能有效发挥防洪、发电、排沙、航运等综合调节功能,库区将采取“冬蓄夏泄”的水位调度方式,最终在防洪控制水位145m正与常蓄水位175m之间形成高差达30m、面积约为340km2的永久性水位季节涨落带,即库区消落带。这是在长江形成的历史中从未出现过的、极其复杂的、特殊而敏感水陆交互生态系统。它拥有大面积的珍贵土地资源,形成了不同的坡地类型,具有农业、林业开发利用价值,但受到坡地水土流失,滑坡、泥石流等地质灾害的威胁,同时又是库区水体富营养化控制因子氮、磷等的主要汇和源。这一特殊的湿地生态系统,属于典型的生态脆弱区。其中,磷既是植物生长的必要养分,也是水体富营养化的重要因素之一,水库建成后,将淹没大量地势平坦,耕作历史长,本身磷含量和外源磷富集较多的土壤,增加了土壤磷向水体释放的风险。 本论文以重庆市小江流域消落带为研究对象,初步将消落带划分为三种不同坡地类型,即缓坡土+石质型坡地,陡//缓坡裸岩型坡地,滩涂淤泥型坡地,在此基础上分析研究了不同海拔高度、不同坡地类型、不同土地利用方式下土壤基本理化性质,土壤磷含量及变化特征,强调了库区不断形成和变化的坡地类型与土壤磷含量及变化之间的内在联系,得出了以下主要结果： 1.通过对土壤磷数据的分析,探索不同坡地类型土壤磷分布特点,结果表明不同坡地类型对磷素有汇源效应：缓坡土+石质型坡地由于作物种类多样,人为干扰大,磷素形态变幅较大,有效性高的磷酸二钙型/(Ca2-P/)、磷酸铝盐/(Al-P/)、磷酸八钙型/(Cas-P/)及易活性的磷酸铁盐/(Fe-P/)易在土体中累积,加强了对水体富营养化的威胁；陡//缓坡裸岩型坡地上覆土体缺乏,磷素含量均较低,人为干扰小,变化幅度较小；稳定滩涂淤泥型坡地位于水土交接的敏感地带,水土作用强烈,磷素含量减少,但由于后期发育有机质含量较高的潮土,土壤和植被对磷素有较强的拦截作用,土体有效磷含量有上升趋势。 2.将2008年7月和2009年7月相同地点采样数据进行对比分析,结果表明：连续蓄水后,坡岸表层有机质含量较高的土壤被剥蚀,加上一年中泥沙等沉积物覆盖,不同坡地类型土壤全磷、有效磷含量均减少：不同坡地类型同时影响土壤无机磷形态含量,水溶性较强的Ca2-P及易活化的O-P含量在不同坡地类型均减少,土+石质坡地土壤中富集了大量可溶性磷酸盐,含量降低幅度较大,即增加了磷素向水体溶解的风险,在低海拔滩涂淤泥坡地及缓坡地带,有发育较好的水生湿生植物,对磷素有很有效的截留作用,缓解了土壤磷素向水体释放的数量及风险；一年中周期性干湿交替对土壤磷释放有较大影响,磷在落干时Ca2-P、Ca8-P、Al-P、O-P含量减少,而Fe-P增加,Fe-P在淹水时转化为高活性的Ca2-P和中稳态磷,又以Ca2-P的形态释放出来。在较低海拔已经多次淹水-落干,土壤环境中磷释放作用明显,而且对于植被的破坏效应加强,减低了土壤、植被对磷素的截留作用,增加了可溶性无机磷形态Ca2-P、Ca8-P、Al-P、及易活化的O-P从土壤向水体释放的可能性,增加了水体富营养化的威胁。3.通过对2008年和2009年无机磷形态与有效磷的相关性和线性回归分析得出,小江流域消落带中,磷酸二钙型/(Ca2-P/)、磷酸铝磷/(A1-P/)、磷酸八钙型/(Ca8-P/)是有效磷的主要磷源,磷酸铁磷/(Fe-P/)是重要磷源,闭蓄态磷/(O-P/)在强烈还原下能转化为有效性较强的形态,是潜在磷源。 对于消落带不同坡地类型应因地制宜,合理利用。本文在上述研究的基础上,提出了自己的意见和建议,以期对防治三峡库区消落带水体富营养化和不同坡地土地的可持续利用提供一些借鉴。 Three Gorges Project is the largest water control project in the world at present. The reservior areas will adopt the 'storage in winter and discharge in summer' attemper manner of water-level, in the effort to bring into play on the compositive function of controling and preventing floods、power generation、shipping,and at last, has fromed a 340 square and 30 meters drawdown areas between the altitud 145 meters and 175 meters.This is a sensitive terrestrial-aquatic transverse zone which had ever seen in the Yangtze river history,It possess of more of precious land resourse,has formed different shape of slope land,which have the value of a agriculture and forestry,andis under threat of Geological Disasters.At the same time, it also the collection and fountain of major factors Nitrogen, phosphate and potassium for eutrophication.This especial wetland ecological system is a typcal fragile Eco-regions.P is not only the indispensable nutrient to make the plants grow,but also one of factors of trigger eutrophication. After Reservoir construction, it will submerge more Purple soil which is rich in P originally,and enriehment exogenous P because of the flat terrain and the long history of eultivate, all these are inereased the risk of P coming into water from the soil. The search area of this paper is Xiao jiang river basin drawdown areas. Firstly,the slope shape of drawdown areas has been divided into three:the gentle slope bedrock and earth slope; the naked rock slope; the silting beach slope. on that basis,this paper studied the distributional and change characteristics of the Soil Phosphorus in different elevation,different slope shape, different land use.It emphasize the the inherence affiliation beeween the slope shape and the Soil Phos orus distributional and change characteristics.The results are: 1. Through the analysis on the data of P,this paper research into the distributional characteristics of different slope shape.the result shows:phosphorus of the gentle slope bedrock and earth slope changed by a large margin,because of the very rich plant species and the intense human disturbance, therein,the high efficiency type of inorganic phosphorusCa2-P、Al-P、Ca8-P, and high activity type Fe-P proned to accumulate in the soil, and it will enhance the threat of eutrophication; the naked rock slope is lack of soil,so the content of avaliable phosphorus and a water-soluble phosphorus is small,the change margin is low; phosphorus of the silting beach slope reduced,these are related to the intense water-soil effect in the water-soil boundary.But with the development of Drab Soil,the avaliable phosphorus showed escalating trend. 2. Through the contrast analysis of the data in the same place in 2008 and 2009,the result shows: due to the surface layer soil with higher organic matter had been denude, add the influence of sediment deposition,the total P, available P reduces. On the one hand different slope shape has also impair the inorganic phosphorus in soil:the content of high water-soluble type Ca2-P and high activity type O-P reduces; inorganic P content in the gentle slope bedrock and earth slope decresa in rice rate,due to the high enrichment of water-soluble types of inorganic phosphorus,so enhance the risk that P dissolve to water; in the low altitudes silting beach slope, where growed aquatic plants and wetland plants,due to the screen function,it will ease the risk of eutrophication. On the other hand, periodic alternation of wetting-dry has also impair thechange of inorganic phosphorus in soil: the content of Ca2-P、Ca8-P、Al-P、O-P will decreaase in the dry environment,and the Fe-P increase;in the wet environment, Fe-P will transform the high activity type Ca2-P,and transmit in the form.In the low altitudes, where have been wetting-dry many times,the release P from the soil to water is evidently,add to the detroy of plants,so the high efficiency type of inorganic P Ca2-P、Al-P、Ca8-P, and high activity type Fe-P proned to release to water, and it will enhance the threat of eutrophication. 3.Through eorrelation analysis on the data in 2008 and 2009,showed that Ca2-P, Al-P,Ca8-P are the main sources of available Phosphorus, Fe-P was an important source, while the other types of inorganic phosphorus are smaller eontribution to the available Phosphorus. To the different type of slope land, we should adjust measures to local conditions,and use it in reason。I put forward my views and suggestions on the basis of the above research result, and look forward to offering some reference to prevent an control the eutrophication and advance the sustainable utilisation of the different shape of slope land in the environment in Three Gorges reservior areas.

关 键 词： 消落带 坡地类型 无机磷形态 变化特征

分 类 号： [S71 X52]

领　　域： [农业科学] [环境科学与工程]