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Mahwah, NJ, United States

Zhang W.,Wuhan University | Wang Y.,Wuhan University | Peng H.,Wuhan University | Li Y.,Wuhan University | And 2 more authors.
Water Resources Management | Year: 2010

As the demand for water continuously increases with population growth and economic development, the gap between water supply and demand in China has become increasingly wide. In recent years worsening water pollution has caused this gap to become much more serious. Conventional allocation pattern, which mainly considers water quantity as the key factor, is no longer satisfying the water allocation need. A coupled water quantity-quality model in a river basin is presented in this paper to provide a tool for water allocation schemes analysis. The pollutants transport and hydrological cycling processes in a river basin are involved in the model. A river network is divided into different reaches. According to the division of river network, the areas out of the river are divided into a series of tanks. In each tank, hydrologic processes, pollutant loading production, water demand of users and water supply are calculated. In river network, hydrodynamics processes and water quality are simulated. Water quantity and quality exchanges between each tank and river are also considered. The time step of water quality calculation is 24 h, the same with that of water quantity calculation. In each time step period, the connections of river reaches and tanks are realized through the exchange of water quantity and quality between rivers and tanks: pollutants discharge from tanks to rivers and water intake from rivers to satisfy water demand in tanks. The water use in each tank includes three types: domestic, industrial and agricultural water use. Water allocation schemes are one of the input conditions of the model. Using the proposed model, in each tank, water demand and deficit of different uses, in both water quantity and quality, can be obtained under different water allocation schemes. According to the water deficit, water allocation schemes are analyzed to make proper allocation schemes. In this aspect, the proposed model can also be thought as a water allocation model. The model is tested and applied to the Jiaojiang River basin, Zhejiang Province, China, to analyze the different water resource allocation schemes. © Springer Science+Business Media B.V. 2009.

Mager E.M.,University of Miami | Brix K.V.,University of Miami | Gerdes R.M.,Cold Spring Harbor Laboratories | Ryan A.C.,Hydroqual Inc | Grosell M.,University of Miami
Ecotoxicology and Environmental Safety | Year: 2011

As the first step toward parameterization of a chronic lead (Pb) biotic ligand model (BLM) for Ceriodaphnia dubia, 7-d toxicity tests were performed in waters modified to evaluate the influences of hardness, DOM (as Suwannee River NOM and Aldrich humic acid (HA)), pH (buffered with 4mM MOPS) and alkalinity on the chronic toxicity of Pb. Calculated EC20s for the control base water test and each of the most extreme modified test waters were as follows in γgL-1 Pb (95% confidence interval): base water control=45 (14-53), 5mM CaSO4=22 (12-30), 32mgL-1 DOM=523 (388-573), 2.5mM NaHCO3=73 (21-120) and pH 6.4 buffered with MOPS=3.9γgL-1 Pb (1-5). Results indicate that hardness does not protect against chronic toxicity of Pb to C. dubia, whereas HA does protect at the highest concentration tested (597γM). Additionally, our findings suggest that low pH increases the chronic toxicity of Pb whereas increased alkalinity is protective. The findings reported herein support the need for a chronic Pb BLM as an alternative approach to hardness-based regulations. © 2010 Elsevier Inc.

Mager E.M.,University of Miami | Esbaugh A.J.,University of Miami | Brix K.V.,University of Miami | Ryan A.C.,Hydroqual Inc | Grosell M.,University of Miami
Comparative Biochemistry and Physiology - C Toxicology and Pharmacology | Year: 2011

The acute toxicity of lead (Pb) was examined for fathead minnows (Pimephales promelas; 96-h) and daphnids (Ceriodaphnia dubia; 48-h) in waters modified for hardness (as CaSO4), dissolved organic carbon (DOC; as Aldrich humic acid) and alkalinity (as NaHCO3) for parameterization of an acute freshwater biotic ligand model (BLM). Additionally, acute (96-h) and chronic (30-d) bioassays were performed for P. promelas to more clearly define the influence of pH (5.5-8.3) on Pb toxicity as modified by addition of HCl or NaOH using an automated titration system. Results indicate that Ca2+ is protective against acute Pb toxicity to P. promelas but not C. dubia. Strong protection was afforded by DOC and NaHCO3 against acute Pb toxicity to P. promelas, whereas milder protection was observed for C. dubia with both parameters. Dissolved Pb LC50s from the P. promelas pH bioassays revealed a complex effect of pH on Pb toxicity, likely explained in part by Pb speciation and the competitive interaction of H+ with ionic Pb2+. Chronic pH bioassays also demonstrated that 30-d growth is not impaired in fathead minnows at relevant Pb concentrations. The findings reported herein suggest that development of separate BLMs for P. promelas and C. dubia should be considered. © 2010 Elsevier Inc.

Esbaugh A.J.,University of Miami | Esbaugh A.J.,University of Texas at Austin | Mager E.M.,University of Miami | Brix K.V.,University of Miami | And 2 more authors.
Aquatic Toxicology | Year: 2013

The toxicity of many metals is impacted by environmental pH, through both competition and complexation by hydroxide and carbonate ions. To establish safe environmental regulation it is important to properly define the relationship between pH and metal toxicity, a process that involves manipulating the pH of test water in the lab. The current study compares the effects of the three most common pH manipulation methods (carbon dioxide, acid-base addition, and chemical buffers) on acute Pb toxicity of a model fish species, Pimephales promelas. Acidification of test water revealed that the Pb and Pb2+ LC50 values were impacted by the pH manipulation method, with the following order of effects: HCl

Takamatsu M.,Hydroqual Inc | Barrett M.,University of Texas at Austin | Charbeneau R.J.,University of Texas at Austin
Journal of Environmental Engineering | Year: 2010

Treatment of storm-water runoff may be necessary before discharge to surface waters. In urban areas, space constraints limit selection of conventional treatment systems, and alternative systems are needed. This research program involves design and laboratory testing of a small footprint nonproprietary detention basin which consists of pipes and box culvert sections with a specialized inlet and outlet system. This system can be placed below grade near the roadway section as part of the conventional drainage system and does not require additional right-of-way. A mathematical model, based entirely on hydraulic principles, is developed to estimate particle removal efficiency of the rectangular detention basin for the treatment of storm-water runoff by extending ideal horizontal tank theory under the condition in which water level is varied. A physical model was built in 1/5 scale to measure particle removal performance and validates the conceptual model. Experiments were performed for steady inflow conditions with different inflow rates, durations, and suspended sediment concentrations. Measured time series outflow suspended sediment concentrations and particle removal efficiency compare well with calculated results from the conceptual model. The outflow particle-size distribution can also be estimated using the conceptual model. © 2010 ASCE.

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