PHREATOPHYTE EVAPOTRANSPIRATION AND ITS POTENTIAL REDUCTION WITHOUT ERADICATION1

ABSTRACT: The continuous availability of ground water to riparian phreatophytic vegetation results in large evapotranspiration (ET) losses in summer. Chemical or physical eradication of this vegetation can have undesirable environmental side effects. Spraying phreatophyte foliage with a nontoxic antitranspirant (AT) may reduce transpiration without eradication. Transpiration rate per unit leaf area was similar for several phreatophyte species, but ET per unit land area of phreatophytes depneds more on stand density than species. The mean ET for saltcedar in June was 8.1 mm/day measured by Bowen ratio, compared with 7.9 mm by lysimeters. ATs and growth-retardants reduced transpiration by over 50 percent in laboratory tests where foliage was thoroughly sprayed. In the field AT sprayed by a back-pack mistblower reduced ET by 20–35 percent initially and 10 percent after a month. No ET reduction occurred when AT was sprayed by helicopter on saltcedar, because excessive droplet size and heavy salt deposits on the foliage resulted in poor spray adherence. Wax-based AT was relatively nontoxic to fish and wildlife. Dissolved oxygen could be reduced for aquatic life, but further AT dilution in streams and ponds would minimize this. Helicopter spraying may affect bird nests and egg hatchability. Although ATs significantly reduce ET, their high cost and spraying difficulties preclude current use on phreatophytes. With improvement they may economically help to conserve water in riparian areas in future years.     

FOG DRIP IN THE BULL RUN MUNICIPAL WATERSHED,OREGON1

ABSTRACT: Net precipitation under old growth Douglas fir forest in the Bull Run Municipal Watershed (Portland, Oregon) totaled 1739 mm during a 4Cbweek period, 387 mm more than in adjacent clearcut areas. Expressing data on a full water year basis and adjusting gross precipitation for losses due to rainfall interception suggest fog drip could have added 882 mm (35 in) of water to total precipitation during a year when precipitation measured 2160 mm in a rain gage in a nearby clearing. Standard rain gages installed in open areas where fog is common may be collecting up to 30 percent less precipitation than would be collected in the forest. Long term forest management (Le., timber harvest) in the watershed could reduce annual water yield and, more importantly, summer stream flow by reducing fog drip.     

Book Reviews

Books reviewed:
Thomas Drabek, Disaster-induced Employee Evacuation
Hugh Brammer, Agricultural Disaster Management in Bangladesh
Boris Porfiriev, Disaster Planning and Emergency Management in Russia
Patrick Bracken and Celia Petty, eds, Rethinking the Trauma of War
R. Cohen and F. M. Deng, eds, The Forsaken People: Case Studies of the Internally Displaced
Tom Trier and Lars Funch Hansen, eds, Conflict and Forced Displacement in the Caucasus: Perspectives, Challenges and Responses     

循环经济的范式研究

发展循环经济是落实科学发展观、实现经济增长方式根本性转变的重要途径。借鉴“范式”理论探讨和研究了循环经济范式替代末端治理范式的变革：①自然资源的价值得到重估。循环经济范式中将自然资源列为最重要的资源形式。认为它是人类社会最大的资源储备，提高资源生产率是解决环境问题的关键。②不同生态伦理得到整合、提升。循环经济的生态伦理基础强调“生态价值”的全面回归．主张在生产领域和消费领域向生态化转向，承认“生态位”的存在和尊重自然权利。它既包含了现代人类中心主义、生命中心主义和生态中心主义兰种生态伦理追求人类道德完善的合理成分。又补充了各自其不完善的方面o③生态阈值的研究得到深化。循环经济范式的基本前提之一是认为生态阈值是客观存在的。强调在生态阈值的范围内合理利用自然资源．从原来的仅对人力生产率的重视转向在根本上提高资源生产率。在尊重自然的基础上切实有力地保护生态系统的自组织能力。实现经济发展和环境保护的目的。④深层生态学的研究得到加强。循环经济范式是一种深层生态学。符合天人调谐的理念。它不仅强调技术进步．而且将制度、体制、管理、文化等因素通盘考虑，注重观念创新和生产、消费方式的变革．树立了人与自然和谐发展的价值观念。     

基于变更平衡表的土地利用演化信息提取与预测方法研究——以苏州市为例

变更平衡表为国土资源管理部门历年实地调查、汇总所得,精度高,目前的研究中对其深入的应用较少,基于变更平衡表的应用方法研究可为区域土地利用演变信息提取与预测提供帮助。推导了由连续年份的年度变更平衡表求多年周期的平衡表的方法,提出了基于土地利用综合动态度分析土地利用有序程度的思路,探讨了利用连续年份的变更平衡表预测任意年份土地利用结构的方法,并基于传统方法进行了改进,提出了利用矩阵开方法求预测概率矩阵。应用苏州市一定时期的连续年份的年度变更平衡表对上述方法进行了验证,结果表明:提出的信息提取方法有效,预测结果可信;在分析期内(1998~2008年),苏州市耕地大量减少的去向是各类建设用地增加的来源,区域土地利用有序程度较高;预测显示至2020年土地利用结构变化仍将维持农用地、耕地不断减少和建设用地总量不断增加的趋势,但转化的速率将有所放缓;对变更平衡表的深入应用有一定的借鉴意义。     

The evolution of mass balance models of persistent organic pollutant fate in the environment

Current approaches to modelling the fate of persistent organic pollutants (POPs) in the environment have evolved in response to four dominant characteristics of these substances; namely: (1) the presence of POPs in virtually all environmental phases and the ease with which they move from one to the other requires multi-compartmental modelling. Describing transport across phase boundaries becomes as, or even more, important as quantifying transport within the phases; (2) POPs may persist in the environment for many decades. For chemicals that 'have time', concepts such as equilibrium partitioning and steady-state become more important than for short-lived substances whose fate is more controlled by the rates of transformation; (3) measuring POPs is difficult and expensive and observed concentrations of POPs are not available in high spatial or temporal resolution. Consequently, high resolution tends not to be a high priority in POP models; and (4) detrimental effects of POPs often manifest themselves in top predators, which has led to a focus on modelling biotic uptake and transfer within food chains. The task of building a POPs model is viewed as combining the four 'building blocks' of partitioning, transport, transformation and source data with the help of the law of the conservation of mass. Process models, evaluative models, models of real local, regional and global fate, as well as biological uptake models are presented and references to numerous examples are provided. An attempt is made to forecast future directions in the field of POPs modelling. It is expected that modelling techniques that do not rely on quantitative emission estimates as well as approaches that take into account spatial, temporal and climatic variability as well as parameter uncertainty will increase in importance. Finally, the relationship between modelling POPs and models of other pollutant issues is addressed, as are potential interactions between POPs and pollutant issues such as eutrophication, acidification and global climate change.     

关于焦化行业CO2排放核算方法的探讨

本文分析了适用于焦化行业通用CO₂排放核算方法,在此基础上结合我国焦化行业工艺和原料的特征,采用排放因子法和物料衡算法等两种方法对10家典型焦化企业CO₂排放进行核算。结果表明:物料衡算法能很好地反映不同类型焦化企业的排放特征;排放因子法对我国独立焦化企业存在碳排放量系统性高估的可能。为此,建议我国焦化企业可借鉴德国焦化企业的碳核算经验,采用碳平衡法对不同类型的焦化企业(单元)的碳排放量进行核算,并完善相关的统计和监测技术。     

长三角重点生态功能县域生态资产损益核算

限制开发的重点生态功能县域承担着生态保护与经济发展双重使命,如何实现生态与发展互促共进及生态产品价值化是当前面临的极大难点,生态资产损益核算为量化区域资源有偿使用、生态保护修复、生态文明绩效评价等提供了有效途径。以浙江省嵊州市作为长三角地区重点生态功能区的典型县域,基于栅格尺度评估了近20年生态资产存量与流量时空动态变化,并利用地理探测器结合人类活动类型监测分析了生态资产损益的驱动因素。结果表明：2000—2018年,由于森林生态资产质量降低及面积减少,嵊州市近60%区域的生态资产存量呈减少趋势,而生态资产流量总价值与单位面积价值均增益10%以上。相对于自然因素,社会经济因素对嵊州市生态资产损益平均贡献度更大,为17%。县域城镇化导致粮食供给轻微减损,70%以上乡镇生态资产增益,特别是石璜镇生态保护成效较突出。     

我国生态环境资产负债表编制框架研究*

本文根据生态环境资产负债表的基本概念和理论,提出了生态环境资产负债表编制的总体框架,同时,针对环境容量资产、环境质量产品、生态产品资产的特点,分别建立了相应框架体系,提出了环境资产负债表的应用决策方向。本文研究成果对于确立统一的生态环境资产核算标准和方法、使我国生态环境资产负债核算工作逐步规范化、制度化的轨道具有重要的现实意义。     

Parameterization of Albedo over Heterogeneous Surfaces in Coupled Land-Atmosphere Schemes for Environmental Modeling. Part I: Theoretical Background

In grid-based environmental models, the underlying surface consists of patches of solid and liquid parts and different plant communities, creating a very heterogeneous picture in the grid cell. In these cases, numerical modelers usually use a simple arithmetic average to determine the grid-cell albedo, a key variable in the parameterization of the land-surface radiative transfer over the grid cell. The object of this paper is to consider the assumptions for aggregating the albedo over a very heterogeneous surface where various surfaces occur at different heights, and, then propose a method for deriving a general expression for it. The suggested expression for the albedo is compared with the conventional approach, for the two-patches grid-cell with a simple geometrical distribution and different heights of its components. A numerical test is performed to compare the two approaches by numerical simulation of the evolution of the surface temperature over the particular grid-cell. Specifically, a one-dimensional land-surface model was applied to an isolated rocky grid-cell with a hole in the center; the model was forced with meteorological observations taken on July 17, 1999 in Philadelphia, PA.