Sorption and desorption kinetics of diuron,fluometuron, prometryn and pyrithiobac sodium in soils

Abstract

The sorption and desorption characteristics of four herbicides (diuron, fluometuron, prometryn and pyrithiobac‐sodium) in three different cotton growing soils of Australia was investigated. Kinetics and equilibrium sorption and desorption isotherms were determined using the batch equilibrium technique. Sorption was rapid (> 80% in 2 h) and sorption equilibrium was achieved within a short period of time (ca 4 h) for all herbicides. Sorption isotherms of the four herbicides were described by Freundlich equation with an r² value > 0.98. The herbicide sorption as measured by the distribution coefficient (K_d) values ranged from 3.24 to 5.71 L/kg for diuron, 0.44 to 1.13 L/kg for fluometuron, 1.78 to 6.04 L/kg for prometryn and 0.22 to 0.59 L/kg for pyrithiobac‐sodium. Sorption of herbicides was higher in the Moree soil than in Narrabri and Wee Waa soils. When the K_d values were normalised to organic carbon content of the soils (K_oC), it suggested that the affinity of the herbicides to the organic carbon increased in the order: pyrithiobac‐sodium < fluometuron < prometryn < diuron. The desorption isotherms were also adequately described by the Freundlich equation. For desorption, all herbicides exhibited hysteresis and the hysteresis was stronger for highly sorbed herbicides (diuron and prometryn) than the weakly sorbed herbicides (fluometuron and pyrithiobac‐sodium). Hysteresis was also quantified as the percentage of sorbed herbicides which is not released during the desorption step ω = [n_ad / n_de ‐1] x 100). Soil type and initial concentration had significant effect on ω. The effect of sorption and desorption properties of these four herbicides on the off‐site transport to contaminate surface and groundwater are also discussed in this paper.     

Hazardous waste site identification using aerial photography: A pilot study in Burlington County,New Jersey,USA

The objective of the project was to identify all hazardous waste sites in Burlington County, New Jersey that could be detected on existing, medium-scale aerial photographs of the county. The complete set of over 1000 black- and-white stereopairs at a scale of 1:12,000 was carefully examined for initial identification of possible sites. All suspicious sites were examined again on color transparencies of the county at the same 1:12,000 scale. Out of the 1094 black- and-white photos, 250 required further checking on color transparencies using a zoom stereoscope. This examination resulted in a final identification of 67 sites, the locations of which were delineated on 1:24,000 USGS maps. The use of air photo interpretation techniques provided an effective procedure for identifying waste sites quickly as well as providing a useful demonstration program for county and state officials.     

垃圾填埋二次污染的危害与防治

介绍了垃圾卫生填埋中二次污染的危害,指出垃圾卫生填埋场建设和填埋操作中为防止填埋释放物对周围环境的二次污染所应采取的防渗、收集、处理和利用等措施,探讨了在垃圾卫生填埋场建设和填埋操作中应注意的问题及应着重考虑的方面.     

INTEGRATED MODELING FOR WATERSHED MANAGEMENT: MULTIPLE OBJECTIVES AND SPATIAL EFFECTS1

ABSTRACT: This paper presents an optimization framework for prioritizing sites for wetlands restoration on a watershed or landscape scale. The framework is designed for analyzing the potential environmental impacts of alternative management strategies while accounting for economic constraints, thereby aiding decision makers in explicitly considering multiple management objectives. The modeling strategy consists of two phases. First, relationships between the configuration of land use types in a watershed and valued ecosystem services are specified mathematically. Second, those functions are incorporated into a spatial optimization model that allows comparisons of the expected environmental impacts and economic costs of management strategies that change the configuration of land use in the watershed. By way of a stylized example, this paper develops the general structure of the framework, presents simulation results based on two production functions for ecosystem services, and discusses the potential utility of the methodology for watershed management.     

Development of a database of landfills and dump sites in Asian countries

This article briefly summarizes the limited landfill/dump information available for developing Asian countries, and introduces a database that aims to close the information gap through collecting and sharing data. Developing nations usually try to adapt the systems and technologies of developed countries. However, this approach may not be appropriate because of differences in socioeconomic, cultural, and political backgrounds. Many waste management projects fail after operations are transferred to local authorities owing to a lack of funds to cover the high operational expenses. Some successful projects have been adapted to local conditions, although the information on these successes is not often available for others. Nevertheless, only a few developing countries even have a national inventory of their dumps/landfills, and decision-makers have little awareness of the dumps and their impacts. The database introduced here will gather landfill/dump information from each country and organize it in a comparable format, and it will then be published on the Internet.     

Using Multimedia Modeling to Expedite Site Characterization

GOAL, SCOPE AND BACKGROUND: This paper uses two case studies of U.S. Department of Energy nuclear weapons complex installations to illustrate the integration of expedited site characterization (ESC) and multimedia modeling in the remedial action decision making process. CONCEPTUAL SITE MODELS, MULTIMEDIA MODELS, AND EXPEDITED SITE CHARACTERIZATION: Conceptual site models outline assumptions about contaminates and the spatial/temporal distribution of potential receptors. Multimedia models simulate contaminant transport and fate through multiple environmental media, estimate potential human exposure via specific exposure pathways, and estimate the risk of cancer and non-cancer health outcomes. ESC relies on using monitoring data to quantify the key components of an initial conceptual site model that is modified iteratively using the multimedia model. CASE STUDIES: Two case studies are presented that used the ESC approach: Los Alamos National Laboratory (LANL) and Pantex. LANL released radionuclides, metals, and organic compounds, into canyons surrounding the facility. The Pantex Plant has past waste management operations which included burning chemical wastes in unlined pits, burying wastes in unlined landfills, and discharging plant wastewaters into on-site surface waters. CONCLUSIONS: The case studies indicate that using multimedia models with the ESC approach can inform assessors about what, where, and how much site characterization data needs to be collected to reduce the uncertainty associated with risk assessment. Lowering the degree of uncertainty reduces the time and cost associated with assessing potential risk and increases the confidence that decision makers have in the assessments performed.     

生活垃圾填埋产沼的提取净化利用

垃圾填埋是目前我国各城市广为采用的垃圾处理方式，但垃圾填埋产沼以后对沼气的回收利用却不被人们所熟知和重视。由此造成了对可开发利用的二次能源的极大浪费，而沼气对周围环境也造成了严重的污染并对大气臭氧层造成了破坏。本文阐述了垃圾填埋产沼回收的必要性和经济性，对垃圾填埋产沼提取利用、制取汽车压缩气的可行性及工艺流程进行了分析和介绍。     

基于Matlab分析的台阶式场地平整方案优化设计

在某市餐厨垃圾处理厂场地平整设计中,利用Matlab软件对台阶式场地平整方案进行优化设计,即在Auto CAD环境下用等高线法计算各级台阶的土方量,用Matlab软件拟合出台阶设计高程和土方量的函数关系式,在约束条件下求解,得到了最优设计高程和基于土方挖填平衡条件下场地平整的最小土方工程量,为工程总平面布置提供优化方案。其分析设计方法可为工业企业台阶式场地的总平面布置设计提供借鉴。     

关于老工业区污染场地管理的探讨

根据在某老工业区第1批28块场地环境调查的实践,对污染场地管理中存在的问题进行了分析并提出了相应改进建议：①获取准确的场地资料难度很大,建议研究制定场地全过程档案管理制度;②工业企业关闭搬迁会产生新的环境污染风险,工业企业关闭搬迁应该成为污染场地管理的重要环节,环保部门应该在工业企业搬迁前介入,严格监管整个过程中的环境污染;③大量区域由于其中污染严重、风险高的场地缺乏修复资金而难以再开发利用,建议结合规划优先启动资金投入低的污染较轻区域修复,并同时对风险较高的污染场地进行风险管控,当区域开发取得一定规模、成就和收益后,可以整合资金力量和资源开展污染较重区域的修复。     

阜新市空气监测点位优化的聚类分析

基于聚类分析法利用数据之间距离系数进行分类的原理,建立空气监测点位聚类分析优化模型,结合阜新市地形、气象及历史监测数据,进行阜新市空气监测点位布设优化应用,优化结果表明:距离相似水平取d=0.3时,环保局(B点)与人民公园(C点)监测点空气污染物浓度分布相似性最高,合并为1点,增设气象台监测点位作为清洁背景点,4个点位构成阜新市空气监测新网络;利用CALPUFF模型模拟对优化后监测点位进行相关性检验。检验结果表明:监测点位优化后SO2浓度与实测值相关系数为0.984,PM10相关系数为0.968,NO2相关系数为0.973。CALPUFF模型模拟值与实际监测值之间相关系数均大于0.75,表明优化后的阜新市空气监测点位具有客观环境代表性;监测点位优化与检验方法具有一定应用价值。