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To better understand the variation of water quality in the Mekong River, sampling and measurement were scheduled twice a week for about 3 years at Vientiane, followed by basic statistical analysis of the observed data. The frequent measurement revealed detailed characteristics of the water quality variation, which had not been detected by monthly observation in the previous studies. The variation in total ionic content was considered to be governed by dilution of the amount of water. Increases in turbidity could be attributed to physical effects including surface soil erosion and bed material resuspension at the time of discharge increase. Nitrogen concentrations were stably low during the low flow period and abruptly increased in May. After the annual maximum in late May, the nitrate concentration steadily decreased regardless of the remarkable rise in the discharge from mid‐July, whereas the ammonium concentration remained at a similar level until October. It was considered that the first small discernable runoff after the long dry season flushed the accumulated nitrogen in the surface soil and mobilized the nitrogen in the riverbed. The variation in phosphorus concentrations was different from that in nitrogen concentrations. During the high flow period, continual dilutions at discharge peaks and occasional large additions of phosphorus by surface runoff were suggested. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The national economy of Lao PDR is highly dependent on water resources. Consequently, the sustainable management of groundwater and successful adaptations to future climate change are major concerns. Climate projections for Lao PDR predict increased rainfall and hot weather, with more intense rainfall events and more frequent and severe droughts and floods. Under climate change, reductions in the amount and quality of groundwater are two critical problems. Reductions of the groundwater level will restrict the access of local people to groundwater resources, thereby posing a threat to food security and livelihoods. Lao PDR suffers from a limited number of human resources with the requisite skills to perform groundwater investigations and provide sustainable management. For the successful implementation of groundwater management plans, limitations associated with funding and technology should be resolved via support from the government and international cooperation. Advanced action plans for capacity building and training courses should be established to strengthen administrative and individual capacities. Technical measures, such as groundwater monitoring, aquifer characterizations, and water treatment systems, should be implemented to manage future climate change and water resource security. 相似文献
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