Electrochemical biosensors for pathogen detection

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A Water-Quality Simulation Model for Well Mixed Estuaries and Coastal Seas: Volume IX, The Computer Program

1. We analysed 41 years of data (1968–2008) from Blelham Tarn, U.K., to determine the consequences of eutrophication and climate warming on hypolimnetic dissolved oxygen (DO).

2. The establishment of thermal stratification was strongly related to the onset of DO depletion in the lower hypolimnion. As a result of a progressively earlier onset of stratification and later overturn, the duration of stratification increased by 38 ± 8 days over the 41 years.

3. The observed rate of volumetric hypolimnetic oxygen depletion (VHODobs) ranged from 0.131 to 0.252 g O2 m−3 per day and decreased significantly over the study period, despite the increase in the mean chlorophyll a (Chl a) concentration in the growing season. The vertical transport of DO represented from 0 to 30% of VHODobs, while adjustments for interannual differences in hypolimnetic temperature were less important, ranging from −11 to 9% of VHODobs.

4. The mean wind speed during May made the strongest significant contribution to the variation in VHODobs. VHODobs adjusted for the vertical transport of DO and hypolimnetic temperature differences, VHODadj, was significantly related to the upper mixed layer Chl a concentration during spring.

5. Hypolimnetic anoxia (HA) ranged from 27 to 168 days per year and increased significantly over time, which undoubtedly had negative ecological consequences for the lake.

6. In similar small temperate lakes, the negative effects of eutrophication on hypolimnetic DO are likely to be exacerbated by changes in lake thermal structure brought about by a warming climate, which may undermine management efforts to alleviate the effects of anthropogenic eutrophication.

Long-term changes in oxygen depletion in a small temperate lake: effects of climate change and eutrophication

Modeling sediment impact on the transport of fecal bacteria.

Modeling impacts of Yangtze River water transfer on water ages in Lake Taihu, China

This comprehensive text perfectly illustrates the principles, basic processes, mathematical descriptions, case studies, and practical applications associated with surface waters. It focuses on solving practical problems in rivers, lakes, estuaries, coastal waters, and wetlands. Most of the theories and technical approaches presented within have been implemented in mathematical models and applied to solve practical problems. Throughout the book, case studies are presented to demonstrate how the basic theories and technical approaches are implemented into models, and how these models are applied to solve practical environmental/water resources problems.

Hydrodynamics and water quality : modeling rivers, lakes, and estuaries

To simulate transport and thermal processes in shallow estuaries, a hydrodynamic model within the framework of the Environmental Fluid Dynamics Code (EFDC) has been developed and applied to Morro Bay, California. For this modelling study, comprehensive field samplings were conducted to record the wetting and drying processes in detail. The bay features a shipping channel with localized rapid topography variations, and flat and shallow topography in the rest of the area. At low tide, more than 60% of the bay area emerges and becomes dry. The Morro Bay Model contains 1609 curvilinear grid cells with resolution varying from 50 to 110 metres. The bay is well mixed vertically and is represented using a single vertical model layer. For computational efficiency, a wet cell mapping technique is implemented in the model. The primary model hydrodynamic forcings included open boundary tidal elevations, freshwater inflows from two creeks, and surface wind stresses. The measured data for model calibration include tidal elevation, current velocity, water temperature, and salinity at six locations for 31 days, from March 9 to April 10, 1998. Comparison between model results and data indicates that the model results match the data reasonably well. The model also simulates the wet and dry processes in Morro Bay realistically. As an application of this calibrated model, a flushing analysis is conducted to determine which areas in Morro Bay are susceptible to poor flushing. It is concluded that the hydrodynamic model presented in this paper can be a useful tool for studying the wetting and drying processes in shallow estuaries.

Wetting and drying simulation of estuarine processes

It is a challenge to apply coupled hydrodynamic, sediment process, and contaminant fate and transport models to the studies of surface water systems. So far, there are few published modeling studies on sediment and metal transport in rivers that simulate storm events on an hourly basis and use comprehensive data sets for model input and model calibration. The United States Environmental Protection Agency (USEPA) in 1997 emphasized the need for credible modeling tools that can be used to quantitatively evaluate the impacts of point sources, nonpoint sources, and internal transport processes in 1D/2D/3D environments. A 1D and time-dependent hydrodynamic, sediment, and toxic model, within the framework of the 3D Environmental Fluid Dynamics Code (EFDC), has been developed and applied to Blackstone River, Mass. The Blackstone River Initiative (USEPA) in 1996, a multiyear and multimillion-dollar project, provided the most comprehensive surveys on water quality, sediment, and heavy metals in the river, and serv...

Sediment and Metals Modeling in Shallow River

Hydrodynamics and water quality : , Hydrodynamics and water quality : , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Zhen-Gang Ji

Papers

Hydrodynamics and water quality : modeling rivers, lakes, and estuaries

Wetting and drying simulation of estuarine processes

Sediment and Metals Modeling in Shallow River

Hydrodynamics and water quality

Calibration and verification of a spectral wind–wave model for Lake Okeechobee