地下水弥散实验研究

本文通过野外实验的方法,确定了地下水含水层的弥散参数,为建立准确可靠的地下水污染预测模型提供依据,对地下水环境质量研究和环境影响评价具有实际意义。     

Farm-level irrigation and the marginal cost of water use: evidence from Georgia

We create a proxy for the cost of irrigation water in Georgia from a sample of Georgia irrigators by investigating the marginal cost of pumping groundwater. We then combine this proxy with agronomic and climatic variables to estimate the response of agricultural water use to differences in the marginal cost of irrigation. The results show that pumping costs are a significant determinant of water use, and imply that agricultural water use would be moderately affected by institutional changes that would explicitly price water.     

Role of refugia in recovery from disturbances: Modern fragmented and disconnected river systems

Habitats or environmental factors that convey spatial and temporal resistance and/or resilience to biotic communities that have been impacted by biophysical disturbances may be called refugia. Most refugia in rivers are characterized by extensive coupling of the main channel with adjacent streamside forests, floodplain features, and groundwater. These habitats operate at different spatial scales, from localized particles, to channel units such as pools and riffles, to reaches and longer sections, and at the basin level. A spatial hierarchy of different physical components of a drainage network is proposed to provide a context for different refugia. Examples of refugia operating at different spatial scales, such as pools, large woody debris, floodplains, below dams, and catchment basins are discussed. We hope that the geomorphic context proposed for examining refugia habitats will assist in the conservation of pristine areas and attributes of river systems and also allow a better understanding of rehabilitation needs in rivers that have been extensively altered.     

石油类地面水环境质量标准的讨论

通过国内一些地区地面水监测成果分析,论证了《地面水环境质量标准》GB3838-88中Ⅱ、Ⅲ类规定的石油类标准值0.05mg/L适用性较差.结合我国目前水质状况和自来水厂的一般处理工艺,提出了修订地面水Ⅱ、Ⅲ类石油类标准的建议.     

Fe0-PRB修复地下水硝酸盐污染数值模拟

基于地下水对流-弥散作用,采用数值分析方法,构建了GMS地下水渗流和硝酸盐污染物迁移三维耦合模型.在污染物迁移过程中,不考虑吸附降解和考虑吸附降解两种工况下,分析了污染物在地下水中的迁移特征.结果表明:地下水和土壤存在天然净化污染物的能力,但不显著,必须采取有效措施控制污染.以零价铁作为PRB墙体介质,并用GMS软件模拟Fe0-PRB修复地下水中硝酸盐的效果.PRB存在时能显著控制污染物的污染范围并降低污染物浓度.PRB厚度为4m时,污染物经过550d开始透过PRB墙,PRB运行10a后,1、2、3号观测井的浓度分别1.712,0.011,0.018mg/L,PRB下游污染羽拖尾明显;PRB厚度为6m时,污染物经过850d开始透过PRB墙,PRB运行10a后,1、2、3号观测井的浓度分别0.52,0.004,0.005mg/L,与4mPRB相比浓度分别降低69.6%、63.6%和72.2%,PRB下游污染羽拖尾仍存在但不明显.污染物迁移数值模拟是评价PRB修复污染地下水效果及确定PRB参数的重要手段.     

Methodological considerations for nitrogen policies in the Netherlands including a new role for research

The Netherlands has attempted to follow EU guidelines in developing national policies to reduce pollution of groundwater by nitrates originating from (over) fertilized agricultural land. The EU has not been satisfied with these policies and this is resulting in legal conflicts. National policies have focused on nitrogen budgeting and on fertilization rates, over-simplifying the crucial role of soils during the leaching of nitrates to groundwater. As an alternative, a dynamic approach using simulation modeling is introduced as is illustrated for a study area in the Netherlands. A number of considerations for future policy directions are suggested, including requirements for research: (i) promotion of research aimed at improving and maintaining nutrient use efficiency at farm level; (ii) promotion of joint learning experiences between farmers and researchers, where farmers’ organizations could act as “research consortia”; (iii) emphasis on site and time specific management (precision agriculture) in policy development, and provision of site-specific advice via modern information and communication technologies; (iv) clearer guidelines for groundwater monitoring procedures, including additional monitoring at greater depths and consideration of groundwater quality from an appropriate regional perspective; (v) groundwater monitoring should take place at locations selected according to specific hydro-geological characteristics, rather than being executed at random and (vi) clear goals that are defined within existing and future policies at EU and international level, should allow for regional differentiation in indicators; these being the outcome of negotiations between farmers or their representatives, policy makers and researchers.     

膜界面探测器在工业污染场地调查中的应用

膜界面探测器是一项采用直接推进技术,可实时提供场地地下挥发性有机物近乎连续分布信息的直接感测工具。以某历史上从事有机氯农药生产的废弃工业场地为例,运用该技术,配置土壤电导率传感器、电子捕获检测器以及氢火焰离子化检测器,对该场地中潜在污染区域进行快速筛选调查,初步确定了土壤和地下水中挥发性有机物污染的热点区域及其三维分布和地层信息,为后续进一步调查方案优化、场地概念模型建立及后续修复方案设计等提供了重要的信息。     

Does efficient irrigation technology lead to reduced groundwater extraction? Empirical evidence

Encouraging the use of more efficient irrigation technology is often viewed as an effective, politically feasible method to reduce the consumptive use of water for agricultural production. Despite its pervasive recommendation, it is not clear that increasing irrigation efficiency will lead to water conservation in practice. In this paper, we evaluate the effect of a widespread conversion from traditional center pivot irrigation systems to higher efficiency dropped-nozzle center pivot systems that has occurred in western Kansas. State and national cost-share programs subsidized the conversion. On an average, the intended reduction in groundwater use did not occur; the shift to more efficient irrigation technology has increased groundwater extraction, in part due to shifting crop patterns.     

基于DRASTIC方法的地下水污染脆弱性评价

目前许多地区的地下水因过度开采以及工业活动而受到了不同程度的污染,特别是在经济发达地区,由于化肥的过度使用。给地下水系统带来了严重威胁。本文结合典型案例研究区一江阴市地下水监测网络及其监测数据,应用AHP（层次分析法）对DRASTIC法各指标权重进行重新确定,并对案例区进行了地下水脆弱性评价。在此基础上,在DRASTIC指标体系中加入硝酸盐浓度因子作为特殊脆弱性影响因子,应用GIS空间分析功能得出研究区地形图。研究结果显示：研究区大部分地区属于较易受污染地区,少数地区不易受污染。脆弱性评价结果较好地符合了水质状况,在指导地下水资源规划以及生产活动具有一定的理论及实际意义。     

Inorganic chemicals in domestic water of the United Arab Emirates

The concentration of selected inorganic chemicals was determined for 396 samples of bottled water, desalinated water, and groundwater used for drinking and domestic purposes in the United Arab Emirates (UAE). The objective of this study was to compare the concentrations of inorganic chemicals in different domestic water types used in the UAE with the World Health Organization (WHO) limits for drinking water. Results of the present study revealed a wide variation in the concentrations of major, minor, and trace inorganic chemicals in domestic water of the UAE. For example, the bottled water sold for drinking is depleted in major ions and the total dissolved solids (TDS) in some brands do not exceed 100 mg/l. On the other hand, some of the domestic water used may contain as much as 3,000 mg/l TDS, which is above the WHO recommended limit for drinking water (500–1,500 mg/l TDS). Similarly, while bottled water is almost free of trace ions and minor constituents, some natural groundwater may have concentrations higher than the WHO recommended limits for drinking water. The cause of this variation is related to the different water sources and the large number of companies producing and distributing drinking and domestic water. Moreover, it is clear that the current controls on domestic water quality in some areas, namely conformance of pH and electrical conductivity measurements with prescribed ranges of values, are currently inadequate. These two parameters are not enough to judge if water is suitable for drinking or not and some consumers may receive domestic water of uncertain quality.