三峡水域氮磷污染对水华暴发/消涨行为的协同影响

藻类生长/消退与藻类对氮、磷的吸收比率ω₁和ω₂相关,ω_i正/负增长分别对应藻类生长时从水体中吸收氮磷的加速阶段和藻类分解时向水体释放氮磷的消退阶段,在特定磷氮比(P/N)范围出现ω₁和ω₂同时突变有可能从理论上解释水华的暴发/消退.根据三峡流域实测数据和藻类吸收氮磷的关联函数,在三维空间表征了随氮磷浓度协同作用导致的ω₁和ω₂在特定P/N区域同时突变所揭示出的水华暴发/消退现象,从而直观、合理地解释了:①适当的P/N范围才可能暴发水华;②如果P/N区间同时满足ω₁和ω₂正向急剧增长的要求,藻类疯长,而ω₁和ω₂同时朝负值方向急剧降低,水华消退;③水华暴发/消退的速率为同一数量级,且水华暴发/消退在氮、磷浓度达到某一敏感范围时将表现出明显的周期性振荡.这些性态可能更真实地反映出水华暴发/消退时藻类对营养盐的吸收/释放机理.     

土地沙化区农民特征与其感知的环境灾害风险的关系分析——基于环境公平视角

论文根据对甘肃省土地沙化区农民的调查数据,运用Logit模型,基于环境公平的视角探讨土地沙化区农民特征与其感知的环境灾害风险的关系。从个体特征上讲,受访者性别和婚姻状况与其感知的环境灾害风险之间的相关关系不显著,受访者受教育程度与其感知的环境灾害风险之间呈显著正相关关系;从经济特征上讲,农民所感知的环境灾害风险主要体现在土地经营收入的损失上,且感知的环境灾害风险与其家庭年总收入之间的关系呈现倒“U”型趋势;从生态环境特征上讲,环境的治理和改善有利于降低农民感知的环境灾害风险。通过分析认为农民所承受的环境灾害风险的不公平一定程度上是农民在社会经济领域所受到的不公平的体现,农民对环境不公平的感知在家庭年总收入10万元左右时最明显,环境不公平主要体现在环境灾害风险对土地经营收入的影响上。农民对生态环境治理效果的认知与对环境公平的感知具有一致性。     

青藏高原东缘三江流域生态功能区建设的措施与影响

三江流域生态环境极度脆弱,严重威胁着中下游地区的社会安全和经济发展。随着西部开发和生态建设的推进,尤其是本地区“香格里拉”旅游热潮的兴起,三江流域已经成为西部开发的重要地区。通过三江流域的生态环境功能区的界定和划分,科学制定研究区的生态环境建设目标,并进行生态环境质量的动态监测和退化过程的预警报,从而在宏观上实现生态环境质量动态管理;通过退化生态系统的恢复重建模式的研究,特别是功能区的建设示范,把目前的生态恢复工程提高到一个新的水平;为保护生物多样性资源,实现区域生态、经济、社会可持续发展提供理论支撑。     

A Conceptual Model of Spatially Heterogeneous Nitrogen Leaching from a Welsh Moorland Catchment

Soil- and stream-water data from the Plynlimon research area, mid-Wales, have been used to develop a conceptual model of spatial variations in nitrogen (N) leaching within moorland catchments. Extensive peats, in both hilltop and valley locations, are considered near-complete sinks for inorganic N, but leach the most dissolved organic nitrogen (DON). Peaty mineral soils on hillslopes also retain inorganic N within upper organic horizons, but a proportion percolates into mineral horizons as nitrate (NO ₃ ^– ), either through incomplete immobilisation in the organic layer, or in water bypassing the organic soil matrix via macropores. This NO ₃ ^– reaches the stream where mineral soilwaters discharge (via matrix throughflow or pipeflow) directly to the drainage network, or via small N-enriched flush wetlands. NO ₃ ^– in hillslope waters discharging into larger valley wetlands will be removed before reaching the stream. A concept of catchment nitrate leaching zones is proposed, whereby most stream NO ₃ ^– derives from localised areas of mineral soil hillslope draining directly to the stream; the extent of these zones within a catchment may thus determine its overall susceptibility to elevated surface water NO ₃ ^– concentrations.     

Impacts of Climatic Change On Peatland Hydrochemistry; A Laboratory-Based Experiment

A laboratory simulation of a reduction in water table height that could be anticipated from current climate change models, resulted in a change in the efficiency with which a valley-bottom wetland acted as a sink/source of nutrients. Effects were confined to the upper 10 cm of the profile, but since this depth has the greatest hydraulic conductivity, it was noted that the effects of hydrochemical changes therein would be readily transferred to receiving waterbodies. Marked changes in leachate chemistry were observed, including increases in nitrate and sulphate concentrations, while concentrations of phenolics, dissolved organic carbon, potassium, iron and ammonium decreased. These changes have implications for the quality and productivity of waters draining wetlands.     

Decision Support System for Managing Oil Spill Events

The Mediterranean environment is exposed to various hazards, including oil spills, forest fires, and floods, making the development of a decision support system (DSS) for emergency management an objective of utmost importance. The present work presents a complete DSS for managing marine pollution events caused by oil spills. The system provides all the necessary tools for early detection of oil-spills from satellite images, monitoring of their evolution, estimation of the accident consequences and provision of support to responsible Public Authorities during clean-up operations. The heart of the system is an image processing–geographic information system and other assistant individual software tools that perform oil spill evolution simulation and all other necessary numerical calculations as well as cartographic and reporting tasks related to a specific management of the oil spill event. The cartographic information is derived from the extant general maps representing detailed information concerning several regional environmental and land-cover characteristics as well as financial activities of the application area. Early notification of the authorities with up-to-date accurate information on the position and evolution of the oil spill, combined with the detailed coastal maps, is of paramount importance for emergency assessment and effective clean-up operations that would prevent environmental hazard. An application was developed for the Region of Crete, an area particularly vulnerable to oil spills due to its location, ecological characteristics, and local economic activities.     

四川水稻气候生态类型分异及区划

本文根据中国光温生态试验资料及四川水稻品比试验与气象观测的历史资料,讨论了早、中稻感温性和对温度的适应性,分析了播期、纬度、海拔等因素与稻种需求积温量的关系,以水稻品种类型对热量的适应性指标为依据,考虑四川水稻气候生态的差异性,划分出水稻综合气候生态类型区。     

我国城镇可持续发展实验区建设的理论与实践

可持续发展综合实验区是我国实施可持续发展战略的重要行动。本文在分析、总结我国城镇可持续发展实验区实践的基础上,提出了建设城镇可持续发展实验区的基本思路     

STREAM TEMPERATURE UNDER AN INADEQUATE BUFFER STRIP IN THE SOUTHEAST PIEDMONT1

ABSTRACT: A paired watershed experiment on the southeastern Piedmont to determine the effect of clearcutting loblolly pine on water quantity, quality, and timing has shown that stream water temperatures we increased as much as 20°F even though a partial buffer strip of trees and shrubs were left in place to shade the stream. Water time minimum stream temperatures were lowered as much as 10°F by the same treatment. A stream temperature model now in use did not predict such elevated temperatures. The authors suggest that forest cover reductions in areas of gentle land relief may elevate the temperature of shallow ground water moving to the stream, even with a substantial buffer strip Ln place.     

AIRBORNE THERMAL MAPPING OF A “FLOW-THROUGH” LAKE IN THE NEBRASKA SANDHILLS1

The Sandhills region represents a tremendous water resource for the State of Nebraska. Small shallow lakes, marshes, and subirrigated meadows are abundant due to interactions between ground water and surface water. One theory relating ground water to lake-flow systems in the Sandhills has been termed the “flow-through” concept. Thermal-infrared remotely acquired images document the flow-through model for a test site in Western Nebraska.