Trifluralin (2,6-dinitro-N, N-dipropy1-4- (trifluormethyl) benzenamine) was applied preemergent to soybean in plots drained or nondrained, in Louisiana. Plots 14.6 ㏊ were arranged to give 1683 g/㏊ of trifluralin. The half life of trifluralin in the top 15㎝ of soil was 42.6 days and 46.0 days in nondrained plot and drained plot, respectively. The concentrations of trifluralin in surface runoff water and subsurface runoff water were 0.62 ng/mL-0.02 ng/mL and 0.06 ng/mL-0.02 ng/mL, respectively. The concentration of trifluralin in runoff water was smaller than 2 ng/mL for trifluralin of U.S. Environmental Protection Agency advisory. Total loss of trifluralin in runoff water was 0.021% of applied amount at drained plots during three month after application. Trifluralin was moved hardly in the water. Subsurface drainage reduced trifluralin losses because concentration of trifluralin in the subsurface runoff water in drained fields was low.

A rainfall runoff model described in this paper which is based on Basin- wide Ecological Model(BAWEM) calculates the fate of agro-chemicals in a watershed located of golf links. The rainfall runoff coefficients of agro-chemicals,which are the dominant parameters to predict the movement of agro-chemicals from soil and turfgrass to downstream water, are estimated. Also, the model is used to estimate the level of health risks the residents around golf links are exposed to. The fidelity of rainfall runoff model of agro-chemicals was validated by the observed data obtained during rainy period. The calculated results from this model were found to be in the same order of that of the observed. The rainfall runoff coefficients of four agro-chemicals used in golf links were 5.4×10 exp (-3), 1.9×10 exp (-3), 3.0×10 exp (-4) and 4.4×10 exp (-3) for flutolanil, isoprothiolane, chlorpyrifos and simazine, respectively. The health risk level to the residents around golf links is evaluated to be rather low: the ratio of estimated dose through drinking water to the 10% of ADI(Acceptable Daily Intake) value or VSD for 10^-6 life time risk varied in the range of 0.005∼0.04 and 0.003∼0.11, respectively, for both the annual mean and maximum monthly mean cases.

An air suction skimmer was selected as a potable skimmer to be developed among the many reviewed skimmers because of its advantages such as simple structure, excellent transportability, and easy deployment. A prototype of the skimmer was fabricated. It was shown that the skimmer operated by a commercial vacuum cleaner has good performance. The maximum suction rate of water and the maximum suction head were 18㎥/㏊ and 2.7m, respectively.

Effluent recycling effect on UASB reactor performances is known as an important operational factor. In the present study, the possibility of intermittent recycle in UASB process for saving the power consumption was examined at different organic loading and various operational modes in recycle time period. The organic removal efficiencies of the reactors operated with the intermittent effluent recycle were considerably higher compared to those without the effluent recycle. In the intermittent recycle mode, the organic removal efficiencies slightly decreased as the non-recycle time period in the operational mode increased. Proper ratio of recycle and non-recycle time period in the mode seemed to be required to prevent the produced biogas from accumulation in the sludge bed, which caused dead zone in the reactor and sludge loss when the gas was escaped from the bed at the certain pressure.

This study was aimed to evaluate the effects of effluent recycling on the UASB reactor performances at the various organic loading rates and influent substrate concentrations. The organic removal efficiency of the reactors operated with effluent recycle were above 85%. However, the efficiencies of the reactors operated without the recycle were below 40% even though the effort to increase the efficiencies was made by changing the influent substrate concentrations and the organic loading rates, and introducing the effluent recycle at the final stage of the experiment. It was realized that the certain amount of effluent recycling from the start-up stage in UASB reactors seemed to be necessary to provide the effective contact chances between the substrate and granular sludge for better performances of the UASB

The problem of supply and transport of sediment from a mountainous catchment is very important in explaining dynamic geomorphology and the hydrological cycle. The discharge of suspended sediment is determined by a morphological system. Human interference to environment is also an important, not negligible factor in sediment production. Moreover, growing concern in recent years for the problems of nonpoint pollution and for the transport of contaminants through terrestrial and aquatic ecosystem,; has highlighted the role of sediment-associated transport in fluvial systems. This study was conducted in forested and quarried catchments in order to clarify the different discharge process and the mechanism of suspended sediment dynamics for each catchment. As a forested catchment, the Yamaguchi River catchment which drains a 3.12 ㎢ area was chosen. On the other hand, the Futagami River basin, which is formed by three subbasins (1.07, 1.59 and 1.78 ㎢), as a quarried catchment was selected. These catchments are situated to the north and east of Mt. Tsukuba, Ibaraki, Japan. The discharge pattern of suspended sediment from the Futagami River basin is more unstable and irregular than that from forested catchment, the Yamaguchi River catchment. Under the similar rainstorm conditions, suspended sediment concentration from quarried catchment during a rainstorm event increases from 43 to 27,310㎎/l. However, in the case of the forested catchment it changes only from nearly zero to 274 ㎎/l. Generally, the supply source of suspended sediment is classified into two areas, the in-channel and non-channel source areas. As a result of field measurements, in the case of the forested catchment the in-channel (channel bed, channel bank and channel margin) is the main source area of suspended sediment. On the other hand, remarkable sediment source area on the quarried catchmen, is the non-channel that is unvegetated ground.

Growing algae spread over open water surface of water hyacinth system the leaves of hyacinth prevented the passage of sunlight through the water surface. The objectives of this study were to investigate the effects of the algae growth on the effluent of water hyacinth wastewater treatment systems operated with the variation of an organic loading rate between 190 to 550 kg COD/ha.day. The effluent from the system contained algae was discharged for about 2-3 weeks from the beginning of experimental operation of water hyacinth systems. BOD and SS concentration of effluents during algae growthing periods were higher than those during the period of algae control. But nitrogen and phosphrous romoval efficiencies during in algae growthing periods were slighty higher than those during the period of algae control.