Modeling trihalomethane formation for Jabal Amman water supply in Jordan

A mathematical model that expresses Total trihalomethane (TTHM) concentration in terms of initial chlorine concentration, total organic carbon, bromide ion concentration, contact time, and pH is developed for Zai water treatment plant which supplies water to Jabal Amman. The developed mathematical model is for constant temperature of 20°C. To adjust model calculated TTHM concentrations for temperatures other than 20°C, another mathematical model that expresses TTHM growth rate as function of temperature is also developed. To test the ability of the two developed models in predicting TTHM concentrations throughout water supplies, a sampling program that aimed at measuring TTHM concentrations in addition to the predictors in the two developed mathematical models namely; chlorine concentration, bromide ion concentration, total organic carbon, temperature and pH throughout Jabal Amman water supply was conducted. The two developed mathematical models and WaterCad, which was used to determine water age, were used to predict TTHM concentrations throughout Jabal Amman water supply. Predicted TTHM concentrations were compared to actual TTHM concentrations measured during the sampling program. Results showed that there is good agreement between measured and, calculated TTHM concentrations, which means that the method presented in this paper, can be used to obtain good estimates of TTHM concentrations throughout networks.     

RECOVERY: A Contaminated Sediment-Water Interaction Model

This paper describes the U.S. Army Corps of Engineers screening-level water quality model (RECOVERY version 3.0) for assessing long-term impacts of contaminated bottom sediments on surface waters. The model couples contaminant interaction between the water column and the bottom sediment, as well as between contaminated and clean bottom sediments. The analysis is intended primarily for organic contaminants with the assumption that the overlying water column is well mixed vertically. The contaminant is assumed to follow linear, reversible, equilibrium sorption and first-order decay kinetics. The system is physically represented as a well-mixed water column (i.e., zero-dimensional) underlain by a vertically-stratified sediment column (i.e., one-dimensional). The sediment is well-mixed horizontally but segmented vertically into a well-mixed surface (active) layer and deep sediment. The deep sediment is segmented into variably contaminated and clean sediment regions. Processes incorporated in the model are sorption, decay, volatilization, burial, resuspension, settling, bioturbation, and pore-water diffusion. The solution couples contaminant mass balance in the water column and in the mixed sediment layer along with diffusion in the deep sediment layers. The model was verified against laboratory and field data, as well as against an analytical solution for the water and mixed sediment layers. These comparisons indicate that the model can be used as an assessment tool for evaluating remediation alternatives for contaminated bottom sediments.     

A Methodology for Space-Time Classification of Groundwater Quality

Safeguarding groundwater from civil, agricultural and industrial contamination is matter of great interest in water resource management. During recent years, much legislation has been produced stating the importance of groundwater as a source for drinking water supplies, underlining its vulnerability and defining the required quality standards. Thus, schematic tools, able to characterise the quality and quantity of groundwater systems, are of very great interest in any territorial planning and/or water resource management activity.This paper proposes a groundwater quality classification method which has been applied to a real aquifer, starting from several studies published by the Italian National Hydrogeologic Catastrophe Defence Group (GNDCI).The methodology is based on the concentration values of several parameters used as indexes of the natural hydro-chemical water condition and of potential man-induced modifications of groundwater quality. The resulting maps, although representative of the quality, do not include any information on its evolution in time. In this paper, this “stationary” classification method has been improved by crossing the quality classes with three indexes of temporal behaviour during recent years. It was then applied to data from monitoring campaigns, performed in spring and autumn, from 1990 to 1996, in the plain of Modena aquifer (central Italy). The results are reported in the form of space-time classification table and maps.     

环境质量评价中关键因子识别的方法研究

应用投影寻踪聚类方法分析环境影响指标的数据资料 ,不但可以根据数据内在特性确定各评价指标的相对权重 ,避免权重人为给定的任意性 ,而且还可以通过逐次筛选找出影响环境质量的关键因子。本文将该方法成功地应用于南京市秦淮河水环境评价中 ,筛选出了影响秦淮河水质的关键因子 ,可供秦淮河水环境监测和治理作参考。另一方面 ,该方法还可以推广应用于其它类似问题的综合分析研究中。     

A modified toxicity testing method using tropical marine microalgae

Toxicity testing of four heavy metals(Cd, Cu, Mn and As) using four species of tropicalmarine phytoplankton, Chaetoceros calcitrans, Isochrysis galbana, Tetraselmis tetrahele and Tetraselmis sp., was carried out in multiwellplates with test volumes of 2 mL and the resultscompared to those of standard, large volume,shake-flasks. IC₅₀ values (concentrations of metalsestimated to inhibit 50% growth relative to thecontrol) were determined after 96 hours based onautomated O.D. readings measured in Elisa microplatesby a Multiskan spectrophotometer. Good agreement wasachieved between O.D. readings and cell countsindicating that this new method is a simple,economical, practical and rapid technique for toxicitytesting, and provides good reproducibility of IC₅₀ values. Results of the toxicity testsindicate that Cu was the most toxic metal (averageIC₅₀ values ranging from 0.04 to 0.37 mg L^-1), followed by Cd (0.06–5.7 mg L^-1), Mn (7.2–21.4 mg L^-1) and As (33.9–319.3 mg L^-1).Test species had different degrees of sensitivity tothe metals tested, with I.galbana and C. calcitrans the mostsensitive to Cu, Cd and Mn. Based on these findingsit is recommended that the existing Malaysian InterimStandards for Marine Water Quality for Cd and Cu be reviewed.     

城市空气质量模糊评价新方法

在权广义距离概念的基础上提出一种新的城市空气质量模糊评价方法,评价过程能充分利用实际数据所包含的各种信息.与模糊综合评判模型的同一应用实例结果进行比较,表明文章提出的评价方法更为有效.     

Development of a New Approach to Cumulative Effects Assessment: A Northern River Ecosystem Example

If sustainable development of Canadian waters is to be achieved, a realistic and manageable framework is required for assessing cumulative effects. The objective of this paper is to describe an approach for aquatic cumulative effects assessment that was developed under the Northern Rivers Ecosystem Initiative. The approach is based on a review of existing monitoring practices in Canada and the presence of existing thresholds for aquatic ecosystem health assessments. It suggests that a sustainable framework is possible for cumulative effects assessment of Canadian waters that would result in integration of national indicators of aquatic health, integration of national initiatives (e.g., water quality index, environmental effects monitoring), and provide an avenue where long-term monitoring programs could be integrated with baseline and follow-up monitoring conducted under the environmental assessment process.     

Development of a Model for Simulation of Solute Transport in a Stream–Aquifer System

A model for simulation of solute transport in a dynamic stream–aquifer system is developed by integrating four existing sub-models. Interface packages are created to link the sub-models. The developed model is successfully used to simulate chloride transport in the stream–aquifer system of the Arkansas River and the Equus Beds Aquifer in Kansas and demonstrates that chloride concentration in the aquifer decreases in the vicinity of the simulated channel over time.     

A combined hydrologic simulation and landscape design model to prioritize sites for wetlands restoration

Most landscape design models have been applied to the problem of maximizing species richness in a network of nature reserves. This paper describes a combined hydrologic simulation and landscape design model designed to prioritize sites for wetlands restoration, where the objective is to maximize the amount of nutrients in non-point-source runoff attenuated in the restored wetlands. Targeted site selection in four small watersheds in the Central Valley resulted in predicted levels of nitrogen attenuation two to eight times greater than that from maximizing wetland area without consideration of the location of the restoration sites. Disclaimer  The views expressed in this paper are those of the author and do not necessarily represent those of the US Environmental Protection Agency. No official Agency endorsement should be inferred.     

Evaluating response surface designs for uncertainty analysis and prescriptive applications of a large-scale water quality model

Environmental models are often too large and cumbersome for effective use in regulatory decision making or in the characterization of uncertainty. This paper describes and compares four response surfaces that could complement a large-scale water quality model, the U.S. National Water Pollution Control Assessment Model (NWPCAM), in simulation and regulatory decision support applications. Results show that a physically based reduced-form model that exploits the mathematical structure of the underlying water quality model is a better predictor of policy-relevant outputs than the polynomial expansions that are frequently used in response surface studies.     

改进的模糊综合评价法在太湖水质类别判定中的应用

水质判别是一个多参数多级别的模糊概念,基础的模糊综合评价法存在局限性,对基础模糊数学法中隶属度函数及最大隶属度原则进行改进,建立一种改进的模糊综合评价法。以太湖流域水质判别为实例验证了此方法比传统的方法更有效,且适合在太湖流域应用。     

"两级质控、第三方运营"水质自动站管理模式初探

以江苏省太湖流域水质自动站管理模式为例,从运维管理、质控管理等角度介绍了“两级质控、第三方运营”水站管理模式的基本结构、概念和优势.     

A Screening Procedure for Identifying Acid-Sensitive Lakes from Catchment Characteristics

Monitoring of Wilderness lakes for potential acidification requires information on lake sensitivity to acidification. Catchment properties can be used to estimate the acid neutralizing capacity (ANC) of lakes. Conceptual and general linear models were developed to predict the ANC of lakes in high-elevation (2170 m) Wilderness Areas in Californias Sierra Nevada mountains. Catchment-to-lake area ratio, lake perimeter-to-area ratio, bedrock lithology, vegetation cover, and lake headwater location are significant variables explaining ANC. The general linear models were validated against independently collected water chemistry data and were used as part of a first stage screen to identify Wilderness lakes with low ANC. Expanded monitoring of atmospheric deposition is essential for improving the predictability of lake ANC.     

大辽河入海口水质在线自动监测系统取样工程的建设与维护

介绍一个以自吸喷射泵为取样泵的水质自动监测系统取样工程建设方案及其日常维护措施。适用于河口和四季分明水域建设水质自动监测站需要,更可在其他类型水域建站时借鉴使用。     

A groundwater flow model for water resources management in the Ismarida plain,North Greece

This paper presents the development of a regional flow simulation model of the stream–aquifer system of Ismarida plain, northeastern Greece. It quantifies the water budget for this aquifer system and describes the components of groundwater and the characteristics of this system on the basis of results of a 3-year field study. The semiconfined aquifer system of Ismarida Lake plain consists of unconsolidated deltaic clastic sediments, is hydraulically connected with Vosvozis River, and covers an area of 46.75 km². The annual precipitation ranges in the study area from 270 to 876 mm. Eighty-seven irrigation wells are densely located and have been widely used for agricultural development. Groundwater flow in this aquifer was simulated with MODFLOW. Model calibration was done with observed water levels, and match was excellent. To evaluate the impacts of the current pumping schedule and propose solutions, four management scenarios were formulated and tested with the model. Based on model results, the simulated groundwater budget indicates that there must be approximately 33% decrease of withdrawals to stop the dramatic decline of groundwater levels. The application of these scenarios shows that aquifer discharge to the nearby river would be very low after a 20-year period.     

A water quality monitoring network design methodology for the selection of critical sampling points: Part II

In order to resolve the spatial component of the design of a water quality monitoring network, a methodology has been developed to identify the critical sampling locations within a watershed. This methodology, called Critical Sampling Points (CSP), focuses on the contaminant total phosphorus (TP), and is applicable to small, predominantly agricultural-forested watersheds. The CSP methodology was translated into a model, called Water Quality Monitoring Station Analysis (WQMSA). It incorporates a geographic information system (GIS) for spatial analysis and data manipulation purposes, a hydrologic/water quality simulation model for estimating TP loads, and an artificial intelligence technology for improved input data representation. The model input data include a number of hydrologic, topographic, soils, vegetative, and land use factors. The model also includes an economic and logistics component. The validity of the CSP methodology was tested on a small experimental Pennsylvanian watershed, for which TP data from a number of single storm events were available for various sampling points within the watershed. A comparison of the ratios of observed to predicted TP loads between sampling points revealed that the model's results were promising.     

A Water Quality Monitoring Network Design Methodology for the Selection of Critical Sampling Points: Part I

The principal instrument to temporally and spatially manage water resources is a water quality monitoring network. However, to date in most cases, there is a clear absence of a concise strategy or methodology for designing monitoring networks, especially when deciding upon the placement of sampling stations. Since water quality monitoring networks can be quite costly, it is very important to properly design the monitoring network so that maximum information extraction can be accomplished, which in turn is vital when informing decision-makers. This paper presents the development of a methodology for identifying the critical sampling locations within a watershed. Hence, it embodies the spatial component in the design of a water quality monitoring network by designating the critical stream locations that should ideally be sampled. For illustration purposes, the methodology focuses on a single contaminant, namely total phosphorus, and is applicable to small, upland, predominantly agricultural-forested watersheds. It takes a number of hydrologic, topographic, soils, vegetative, and land use factors into account. In addition, it includes an economic as well as logistical component in order to approximate the number of sampling points required for a given budget and to only consider the logistically accessible stream reaches in the analysis, respectively. The methodology utilizes a geographic information system (GIS), hydrologic simulation model, and fuzzy logic.