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Abstract:The nonpoint source pollution problem can be controlled by implementing various best management practices (BMPs) in the watershed. However, before such practices are adopted, their effectiveness at various spatial and temporal scales must be evaluated. The objective of this research was to evaluate a suite of BMPs in a pasture-dominated watershed in their effectiveness at controlling nutrient losses. A total of 171 different BMP combinations incorporating grazing and pasture management, riparian and buffer zones, and poultry litter applications were evaluated for their effectiveness using the Soil and Water Assessment Tool (SWAT) model. The SWAT model was parameterized using detailed farm and watershed-scale data. The stochasticity in weather was captured by generating 250 various possible weather realizations for a 25-year period, using measured historical climate data for the watershed. Model results indicated that losses of both total nitrogen, mineral phosphorus, and total phosphorus increased with an increase in litter application rates. For the same application rates, greatest losses were predicted for fall application timings compared to spring and summer applications. Overgrazing resulted in greater nutrient losses compared to baseline conditions for all application rates, timings, and litter characteristics, indicating that overgrazing of pasture areas must be avoided if any improvement in the water quality is to be expected. Variability in weather conditions significantly affected BMP performance; under certain weather conditions, an increase in pollutant losses can be greater than reductions due to BMPs implemented in the watershed. Buffer strips and grazing management were two most important BMPs affecting the losses of total nitrogen and total phosphorus from the pasture areas.

Fullerenol, a water-soluble C(60)-fullerene derivative, has been demonstrated to have the capability to scavenge free radicals in vitro and in vivo. The purpose of this study was to investigate whether fullerenol can scavenge the free radicals that are massively induced during ischemia-reperfusion (I/R) injury of the small intestine, either preventively or therapeutically. Clamping the superior mesenteric artery and vein for 60 minutes to induce I/R injury was performed on male mongrel dogs. Thirty dogs were divided into three groups (10 in each): The control (C) group received no medication; the preventive (P) group received fullerenol (1 mg/kg) intravenously 30 minutes before ischemia; the therapeutic (T) group received the same dose of fullerenol immediately after reperfusion. This study was an experimental randomized trial. Intestinal segments were obtained 10, 20, 30, and 60 minutes after reperfusion; and blood samples and specimens of major organs were taken 60 minutes after reperfusion. Concentrations of lipid peroxidation products, including conjugated diene (CD) and malondialdehyde (MDA), and the level of glutathione (GSH) in intestinal tissue were determined. Serum indicators of liver and renal function were measured. Histologic examination of the small intestine and major organs were also performed. A significant increase in intestinal MDA and CD contents was detected at 30 and 60 minutes after reperfusion. The tissue GSH content, in contrast, was decreased 60 minutes after reperfusion. Administration of fullerenol diminished these changes both preventively and therapeutically. Liver and renal functions were within normal limits in all groups. Moreover no obvious histopathologic additional damage could be found in either the P or the T group. It is suggested that fullerenol can be considered a powerful scavenger for the free radicals induced by I/R injury of the small intestine.

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