两江交汇处水体溶解性有机质的吸收和荧光光谱特征:以渠江-嘉陵江、涪江-嘉陵江为例

利用三维荧光和紫外-可见吸收光谱手段,分析了渠江、涪江和嘉陵江交汇处水体DOM特征变化.结果表明,干支流各采样点水体DOM的FI值1.4,HIX值0.8,表现出明显陆源输入特征,整个研究区域水体混合模式为非保守混合,对交汇处水体DOM地化特征变化有一定贡献,但并非主导因素.河流沿岸不同土地利用类型对交汇处水体DOM特征改变有明显影响,聚类分析发现,所有采样点可分为两大类,一类为沿岸以森林和农田生态系统为主(渠江-嘉陵江交汇处),另一类为沿岸以城市用地为主(涪江-嘉陵江交汇处),前者向干流水体中输入芳香化程度和腐殖化程度较高的DOM,后者以浓度较高而结构相对较简单的DOM输入为主.此外,涪江-嘉陵江交汇处类蛋白质荧光组分信号增强,出现荧光T峰,表明人为活动对水体质量的影响明显.     

县级土地利用动态变化及驱动力分析——以郑州市中牟县为例

以郑州市中牟县为例,利用土地详查和统计数据等资料,建立土地利用动态变化模型,分析了中牟县1996-2008年土地利用数量、速度、程度、区域差异等变化,揭示中牟县土地利用变化特征.同时,采用主成分分析法得出城镇化进程和收入水平提高是影响中牟县土地利用变化的主要驱动因素.     

土地利用战略分区研究框架初探

土地利用战略研究是新一轮土地利用总体规划的重要内容,但目前的土地利用战略研究多是从区域整体角度进行分析,未体现区域内部空间差异,对制定差异化土地政策的指导性不强.土地利用战略分区研究可使分区结果与土地政策调控形成互动机制,提高其指导性,从而促进区域土地合理利用与有序开发,实现区域统筹发展.对土地利用战略分区的主要研究内容与原则、指标体系选择、研究方法与思路等进行了探讨,希望对完善土地利用战略及分区研究有所裨益.     

辽宁浑河流域不同土地类型地表径流和壤中流氮、磷流失特征

采用人工模拟降雨的试验方法,研究了辽宁浑河流域主要土地利用类型的土壤在地表径流和壤中流中所产生的氮、磷流失特征。结果表明,（1）地表径流和壤中流氮、磷流失特征差异显著,地表径流氮、磷输出浓度均表现为降雨初期较高而后逐渐趋于稳定的特征;壤中流氮、磷输出浓度在整个径流过程中保持相对稳定。（2）在整个降雨径流过程中,耕地与草地氮、磷流失均以地表径流为主,随壤中流流失的氮、磷占输出量的比例较小。（3）耕地与草地中地表径流和壤中流氮、磷流失差异表明,土壤的水分下渗滤减机制对氮、磷流失具有很大的削减作用,草地中对总磷的削减作用尤为显著,可达90%以上。     

陕西关中地区土地利用结构风险动态研究

以遥感影像资料为依据,运用地学信息图谱的理论和方法,在RS和G IS的支持下,生成了关中地区1986-2007年的土地利用结构风险变化图谱;并从栅格、地貌单元、坡度带及行政区等多个尺度上分析了土地利用结构风险的时空变化特点。研究结果表明:1986-2007年,关中地区土地利用结构风险先升后降,总体降低。各地貌单元中,平原区土地利用结构风险持续增强;黄土台塬区土地利用结构风险是先增后减,总体加大;其余三类地貌的土地利用结构风险是先增后减,总体变小。各坡度带中,0°～3°段的土地利用结构风险增加,>3°段则是先增后减,总体降低。各地市土地利用结构风险最大的是渭南市,最小的是宝鸡市;渭南、西安两市的土地利用结构风险是先增后减、总体加大,宝鸡、铜川、咸阳三市则是先增后减、总体减弱;区内土地利用结构风险变化情况是经济建设和生态建设两方博弈的结果。     

Adaptation to Climatic Variability and Change: Asian Perspectives on Agriculture and Food Security

The impacts of climate change on potential rice production in Asia are reviewed in the light of the adaptation to climatic variability and change. Collaborative studies carried out by IRRI and US-EPA reported that using process-based crop simulation models increasing temperature may decrease rice potential yield up to 7.4% per degree increment of temperature. When climate scenarios predicted by GCMs were applied it was demonstrated that rice production in Asia may decline by 3.8% under the climates of the next century. Moreover, changes in rainfall pattern and distribution were also found suggesting the possible shift of agricultural lands in the region. The studies however have not taken the impacts of climatic variability into account, which often produce extreme events like that caused by monsoons and El Niño. Shifts in rice-growing areas are likely to be constrained by land-use changes occurring for other developmental reasons, which may force greater cultivation of marginal lands and further deforestation. This should be taken into account and lead to more integrated assessment, especially in developing countries where land-use change is more a top-down policy rather than farmers' decision. A key question is: To what extent will improving the ability of societies to cope with current climatic variability through changing design of agricultural systems and practices help the same societies cope with the likely changes in climate?     

STREAMFLOW TRENDS IN WISCONSIN'S DRIFTLESS AREA1

ABSTRACT: Trends in streamflow characteristics were analyzed for streams in southwestern Wisconsin's Driftless Area by using data at selected gaging stations. The analyses indicate that annual low flows have increased significantly, whereas annual flood peaks have decreased. The same trends were not observed for forested areas of northern Wisconsin. Streamflow trends for other streams in southeastern Wisconsin draining predominantly agricultural land were similar to trends for Driftless Area streams for annual low flows. The causes for the trends are not well understood nor are the effects. Trends in annual precipitation do not explain the observed trends in streamflow. Other studies have found that erosion rates decreased significantly in the Driftless Area, and have attributed this reduction to a change of agricultural practices, which increase infiltration, decrease flood peaks, and increase low flows.     

基于生态系统服务功能价值评估的土地利用总体规划环境影响评价研究

随着全国性、地区性土地利用总体规划的制定与实施，探讨适台于土地利用总体规划环境影响评价的技术方法显得相当重要。在对生态系统服务功能价值评估研究进展进行评述的基础上。分析了生态系统服务功能价值评估在土地利用总体规划环境影响评价中应用的必要性．并结合实例对其应用方法进行了探讨．实例分析表明，生态系统服务功能价值评估在土地利用总体规划环评中的应用具有把土地利用的生态效益转化为简单易懂的货币形式．可为决策者提供直观的生态信息及生态系统服务功能价值。可作为一项量化指标。对土地利用总体规划目标及规划方案的生态效益进行综合评估，且核算简单。有助于节省规划环评的时间和资源等优势，本文还指出了进一步研究的方向。     

A Methodology Framework for Regional Land-use Change Studies based on Landsat TM images: A Case Study in Northeast China

Land-use change is an important aspect of global environment change. It is, in a sense, the direct result of human activities influencing our physical environment. This paper analyzed the land-use change in Northeast China during 1985-2000 based on Landsat TM images. It divides Northeast China into five land-use zones based on the dynamic degree model of land-use: woodland/grassland-arable land conversion zone, dry land-paddy field conversion zone; urban expansion zone, interlocked zone of farming and pasturing and reclamation and abandon zone. The findings include the obvious increase of cropland area, paddy field and dry land increased by 75 and 276 thousand hm2 respectively; urban areas expanded rapidly, areas of town and rural residence increased by 76.8 thousand hm2; areas of forests and grassland decreased sharply with the amounts of 1399 and 1521 thousand hm2 respectively; areas of water body and unused land increased by 148 and 514 thousand hm2 respectively. This paper also discusses the driving     

鄱阳湖乐安江流域非点源氮污染时空变化特征分析

乐安江是影响鄱阳湖水质的一条重要河流，近年来非点源污染迅速增加，水质呈下降趋势。运用GIS手段建立了研究区非点源污染的基本空间信息库，在野外水样监测和土地利用调查的基础上，分析了乐安江流域非点源氮的时空变化特征。氮的流失主要以可溶态形式，TN和DTN全年变化剧烈，在12月份普遍较高，4月份次之，9月份最低。在监测各月份乐安江流域TN浓度的范围为0.09~1.359 mg/L，水质属中营养水平。NO3-N浓度平均值为DTN的65%，是DTN流失的主要形态，其时空分布与TN具有明显的相似性；在丰水期4月份，NH3-N的平均浓度为全年最低水平，平水期9月份NH3-N平均浓度为三氮之首；NO2-N全年含量最低。各种形态的氮浓度在空间上从上游向下游基本呈增加趋势；西南部地区各种形态的氮浓度普遍高于东北部地区，说明上游水质普遍好于下游水质。