Spatial distribution of polybrominated diphenyl ethers in coastal marine sediments receiving industrial and municipal effluents in Kuwait

Polybrominated diphenyl ether (PBDE) concentrations were measured in surficial sediments from coastal sediments receiving industrial and municipal effluents in Kuwait. The summation PBDE concentrations varied by two orders of magnitude ranging from 80 to 3800 pg g(-1)dw. The congener distribution was dominated by BDE 183, with minor contributions from BDEs 154 and 153. The similarity between the congener profile to that of the technical octa formulation (Bromkal 79-8DE) suggests a source of this product in Kuwait. The observed gradient in concentration distribution, with high summation PBDE concentrations near the shore and an exponential decrease seaward, indicates that wastewater discharge from industrial activities in the study area is the primary source of these compounds in the sediments.     

Protective role of nordihydroguaiaretic acid (NDGA) against the genotoxic damage induced by ethynodiol diacetate in human lymphocytes in vitro

Antioxidants and plant products are reported to reduce the genotoxic damage of steroids. In our present study we have tested different dosages of nordihydroguaiaretic acid (NDGA) against the genotoxic damage induced by ethynodiol diacetate in the presence of S9 mix. Treatments with nordihydroguaiaretic acid (NDGA) results in the reduction of the genotoxic damage. A significant decrease was observed at all the tested doses of NDGA in sister chromatic exchanges of number of abnormal cells. The results suggest a protective role of NDGA against the genotoxic damage.     

The Effect of Scale-Up on the Performance of High Energy Scrubbers

An experimental investigation has been carried out to examine the effect of scale-up on the performance of scrubbers for a wide range of operating conditions. A pilot plant with a maximum air flow rate of 400 cfm and a water flow rate of 4 gpm was used for this study. For the same operating conditions, the performance of 1.5 in. orifice type scrubber was found better than that of 1.0 in. size. The results were categorized according to the size of the particles, classed as large (1.5 to 3.5μ diam), medium (0.6 to 1.5μ diam) and small (less than O.6μ diam). Although the magnitude of improvement of the collection efficiency was dependent on the operating conditions, differences to the extent of 20% were obtained. The improvement of the collection efficiency for the larger scrubber was found to be due to the influence of the main stream turbulence.     

Diffusive wave models for operational forecasting of channel routing at continental scale

Operational forecast models require robust, computationally efficient, and reliable algorithms. We desire accurate forecasts within the limits of the uncertainties in channel geometry and roughness because the output from these algorithms leads to flood warnings and a variety of water management decisions. The current operational Water Model uses the Muskingum-Cunge method, which does not account for key hydraulic conditions such as flow hysteresis and backwater effects, limiting its ability in situations with pronounced backwater effects. This situation most commonly occurs in low-gradient rivers, near confluences and channel constrictions, coastal regions where the combined actions of tides, storm surges, and wind can cause adverse flow. These situations necessitate a more rigorous flow routing approach such as dynamic or diffusive wave approximation to simulate flow hydraulics accurately. Avoiding the dynamic wave routing due to its extreme computational cost, this work presents two diffusive wave approaches to simulate flow routing in a complex river network. This study reports a comparison of two different diffusive wave models that both use a finite difference solution solved using an implicit Crank–Nicolson (CN) scheme with second-order accuracy in both time and space. The first model applies the CN scheme over three spatial nodes and is referred to as Crank–Nicolson over Space (CNS). The second model uses the CN scheme over three temporal nodes and is referred to as Crank–Nicolson over Time (CNT). Both models can properly account for complex cross-section geometry and variable computational points spacing along the channel length. The models were tested in different watersheds representing a mixture of steep and flat topographies. Comparing model outputs against observations of discharges and water levels indicated that the models accurately predict the peak discharge, peak water level, and flooding duration. Both models are accurate and computationally stable over a broad range of hydraulic regimes. The CNS model is dependent on the Courant criteria, making it less computational efficient where short channel segments are present. The CNT model does not suffer from that constraint and is, thus, highly computationally efficient and could be more useful for operational forecast models.     

Impact of land-use change on the water resources of the Upper Kharun Catchment,Chhattisgarh, India

Regional Environmental Change - Reliable information on the water balance components today and their future changes is a prerequisite for foresightful and sustainable water management. Basically,...     

Gas Cleaning in a Wetted Butterfly Valve

An attempt was made to demonslrate the utility of a wetted butterfly valve for cleaning flue gases from industrial wastes. Butterfly valves are extensively in use to control the gas pressures in various processes. A small pilot plant with a maximum airflow rate of 400 cfm and water flow rate of 4 gpm was constructed to provide the desired testing conditions. The results indicate that for a pressure drop greater than 30 in. water a collection efficiency of greater than 95% for submicron particles can be obtained. For particles larger than 1.7;u diameter efficiencies of greater than 99% were obtained. The exceptional suitability of wet butterfly valves for gas cleaning is demonstrated by the flexibility to adjust to large variations of gas and liquid flow rates.