The ecological effects of trichloroacetic acid in the environment

Trichloroacetic acid (TCAA) is a member of the family of compounds known as chloroacetic acids, which includes mono-, di- and trichloroacetic acid. The significant property these compounds share is that they are all phytotoxic. TCAA once was widely used as a potent herbicide. However, long after TCAA's use as a herbicide was discontinued, its presence is still detected in the environment in various compartments. Methods for quantifying TCAA in aqueous and solid samples are summarized. Concentrations in various environmental compartments are presented, with a discussion of the possible formation of TCAA through natural processes. Concentrations of TCAA found to be toxic to aquatic and terrestrial organisms in laboratory and field studies were compiled and used to estimate risk quotients for soil and surface waters. TCAA levels in most water bodies not directly affected by point sources appear to be well below toxicity levels for the most sensitive aquatic organisms. Given the phytotoxicity of TCAA, aquatic plants and phytoplankton would be the aquatic species to monitor for potential effects. Given the concentrations of TCAA measured in various soils, there appears to be a risk to terrestrial organisms. Soil uptake of TCAA by plants has been shown to be rapid. Also, combined uptake of TCAA from soil and directly from the atmosphere has been shown. Therefore, risk quotients derived from soil exposure may underestimate the risk TCAA poses to plants. Moreover, TCE and TCA have been shown to be taken up by plants and converted to TCAA, thus leading to an additional exposure route. Mono- and di-chloroacetic acids can co-occur with TCAA in the atmosphere and soil and are more phytotoxic than TCAA. The cumulative effects of TCAA and compounds with similar toxic effects found in air and soil must be considered in subsequent terrestrial ecosystem risk assessments.     

强化环境监测管理提高环境监测地位

总结和回顾了我国环境监测工作开展近三十年来所取得的非凡成绩,阐述了目前环境监测工作同整个环境保护事业相比较,同国外环境监测相比较存在的不足,并进一步提出了以"强化环境监测管理,提高环境监测地位"为核心的几点建议,旨在使我国的环境监测工作能更好地为环境保护和经济建设服务.     

提升生态环境质量促进经济跨越发展

近两年福山区在全力发展社会经济的同时,始终坚持保护与改善生态环境质量,实现经济发展与生态环境保护"双赢".     

小城镇环境保护规划存在的问题与对策

根据全国生态环境保护“十五”计划要求,在计划期间力争60％的小城镇完成环境保护规划,广西小城镇由于经济发展不平衡,部分小城镇还比较落后,且存在较多的环境问题,目前小城镇的环境保护规划尚未得到有效的开展,因此应及时找出问题和差距,并根据存在的问题作出相应的对策,在计划期内是可以完成小城镇环境保护规划的目标,为广西小城镇的可待续发展提供环境保障。     

黄河拉西瓦水电站建设对区域景观格局的影响

本根据水利水电工程对景观格局的影响特征,从拼块类型尺度和景观尺度选出优势度、多样性、均匀度、分离度等8个能全面反映景观格局变化的数量化指数,完善了水利水电工程环境影响评价内容。以黄河拉西瓦水电站为例,对该区域LandsatTM7图像解译和GIS处理,结合工程设计规划,绘制建设前后区域景观格局图,建立空间信息数据库,计算各景观指数,分析其变化趋势。结果表明,黄河拉西瓦水电站区域有16种景观类型,分别属于6种生态系统,拼块类型多样,景观格局复杂,其中草地景观优势度最高,接近80％;建成后拼块类型的景观比例、密度、优势度、分离度等都有一定变化;景观均匀度、多样性指数和人为干扰强度都相应增加。总体上,景观格局没有发生大的变化,区域生态系统的功能和性质也不会改变。     

矿井热害的产生与治理

随着矿井开采深度的增加,矿井高温热害问题会越来越严重。为保障煤炭工业持续健康发展,必须采取相应措施进行治理,建立井下适宜的作业环境,保证矿山生产安全、稳定、高效地向前发展。     

An Evaluation of Vernal Pool Creation Projects in New England: Project Documentation from 1991–2000

Vernal pools are vulnerable to loss through development and agricultural and forestry practices owing to their isolation from open water bodies and their small size. Some vernal pool-dependent species are already listed in New England as Endangered, Threatened, or Species of Special Concern. Vernal pool creation is becoming more common in compensatory mitigation as open water ponds, in general, may be easier to create than wooded wetlands. However, research on vernal pool creation is limited. A recent National Research Council study (2001) cites vernal pools as challenging to recreate. We reviewed documentation on 15 vernal pool creation projects in New England that were required by federal regulatory action. Our purpose was to determine whether vernal pool creation for compensatory mitigation in New England replaced key vernal pool functions by assessing project goals and documentation (including mitigation plans, pool design criteria, monitoring protocols, and performance standards). Our results indicate that creation attempts often fail to replicate lost pool functions. Pool design specifications are often based on conjecture rather than on reference wetlands or created pools that function successfully. Project monitoring lacks consistency and reliability, and record keeping by regulatory agencies is inadequate. Strengthening of protection of isolated wetlands in general, and standardization across all aspects of vernal pool creation, is needed to ensure success and to promote conservation of the long-term landscape functions of vernal pools.     

鉴湖水域环境保护的思考和探讨

本文在对鉴湖水域保护工作历史回顾的基础上,分析了存在的主要问题,提出了在构筑“三大组团、绿色空间”城市框架中,加快鉴湖两岸城中村改造,建设“鉴湖生态林带”,形成联结越城、柯桥两大组团的“绿色生态走廊”的建议,重现“山阴道上走,如在镜中游”。     

Chemistry of Selected High-Elevation Lakes in Seven National Parks in the Western United States

A chemical survey of 69 high-altitude lakes in seven national parks in the western United States was conducted during the fallof 1999; the lakes were previously sampled during the fall of 1985, as part of the Western Lake Survey. Lakes in parks in the Sierra/southern Cascades (Lassen Volcanic, Yosemite, Sequoia/Kings Canyon National Parks) and in the southern RockyMountains (Rocky Mountain National Park) were very dilute; medianspecific conductance ranged from 4.4 to 12.2 S cm^-1 andmedian alkalinity concentrations ranged from 32.2 to 72.9 eqL^-1. Specific conductances and alkalinity concentrations were substantially higher in lakes in the central and northernRocky Mountains parks (Grand Teton, Yellowstone, and GlacierNational Parks), probably due to the prevalence of more reactivebedrock types. Regional patterns in lake concentrations of NO₃ and SO₄ were similar to regional patterns in NO₃ and SO₄ concentrations in precipitation, suggestingthat the lakes are showing a response to atmospheric deposition.Concentrations of NO₃ were particularly high in Rocky Mountain National Park, where some ecosystems appear to be undergoing nitrogen saturation.     

Using the ECLPSS software environment to build a spatially explicit component-based model of ozone effects on forest ecosystems

We have developed a modeling framework to support grid-based simulation of ecosystems at multiple spatial scales, the Ecological Component Library for Parallel Spatial Simulation (ECLPSS). ECLPSS helps ecologists to build robust spatially explicit simulations of ecological processes by providing a growing library of reusable interchangeable components and automating many modeling tasks. To build a model, a user selects components from the library, and then writes new components as needed. Some of these components represent specific ecological processes, such as how environmental factors influence the growth of individual trees. Other components provide simulation support such as reading and writing files in various formats to allow inter-operability with other software. The framework manages components and variables, the order of operations, and spatial interactions. The framework provides only simulation support; it does not include ecological functions or assumptions. This separation allows biologists to build models without becoming computer scientists, while computer scientists can improve the framework without becoming ecologists. The framework is designed to operate on multiple platforms and be used across networks via a World Wide Web-based user interface. ECLPSS is designed for use with both single processor computers for small models, and multiple processors in order to simulate large regions with complex interactions among many individuals or ecological compartments. To test Version 1.0 of ECLPSS, we created a model to evaluate the effect of tropospheric ozone on forest ecosystem dynamics. This model is a reduced-form version of two existing models: , which represents an individual tree, and , which represents forest stand growth and succession. This model demonstrates key features of ECLPSS, such as the ability to examine the effects of cell size and model structure on model predictions.