For the Pinang River, originating in the western highlands of Penang Island, the nature, sources and extent of pollution were studied. The river water samples collected at five selected sites were analyzed for various...For the Pinang River, originating in the western highlands of Penang Island, the nature, sources and extent of pollution were studied. The river water samples collected at five selected sites were analyzed for various physical and chemical parameters, namely temperature, DO, BOD, COD, SS, pH, ammoniac nitrogen (AN), and conductance, Long-term data of rainfall and temperature were analyzed to determine the seasonal variations of the streamflow. The streamflow during the dry season is extremely low compared to the wet season, thus concentrations of contaminants derived from point pollution source increase due to lack of rainfall and runoff events. On the contrary, in the predominantly urban and agricultural catchments, non-point pollution source increases during rainy season through seepage and runoff. Effects of seasonal variations consequently determine the quantity and quality of the water parameters. The Jelutong River, the Dondang River and the Air Itam River carry the seepage from widely urban and residential areas to the main Pinang River systems. Water quality of the Pinang River at different points assessed by the water quality indices was compared. According to the quality indices during the study period, water quality in the upper reaches of the river is medium to good. It dwindled in the plains, due to the seepage from urban areas and discharges from the industrial and agricultural lands.展开更多
The aim of this study was to determine the phytoplankton community structures of reservoirs of different trophic status, located in a cold region. Physical and chemical variables and the phytoplankton communities were...The aim of this study was to determine the phytoplankton community structures of reservoirs of different trophic status, located in a cold region. Physical and chemical variables and the phytoplankton communities were investigated in two reservoirs (Xiquanyan Reservoir and Taoshan Reservoir) in Northeast China in 2009. The two reservoirs showed strong seasonal fluctuations in their physical and chemical composition. Results of the trophic status index indicated that Xiaquanyan Reservoir was mesotrophic, whilst Taoshan Reservoir was eutrophic. Diatoms were the dominant phytoplankton group in Xiquanyan Reservoir throughout all seasons of the study, while in Taoshan Reservoir, diatoms dominated in spring, and cyanobacteria dominated in summer and autumn. This difference was resulted from differences in local environmental factors, including nutrients and hydrology. This study suggests that in mesotrophic reservoirs, nutrients played a key role in controlling seasonal phytoplankton successions, whereas in eutrophic reservoirs water temperature was the key factor in a cold region. Notably, the dominant species in summer in the Taoshan Reservoir was Microcystis, which may produce toxins depending on the ambient conditions, and presenting a risk of local toxin contamination.展开更多
Clay fraction contents distribution in the Senegal River estuary after the building of the anti-salt Diama dam has shown that upstream sediments are very muddy. Clay fraction content is as high as 60 % of sediments in...Clay fraction contents distribution in the Senegal River estuary after the building of the anti-salt Diama dam has shown that upstream sediments are very muddy. Clay fraction content is as high as 60 % of sediments in the middle of the channel with a pronounced downstream decreasing trend on the banks comparing to the contents in the middle of the channel. Towards the river mouth, the fine fraction tends to disappear leading to a shelly sand sediment type essentially. During low water period, clay fraction contents increase particularly at the vicinity of the dam reservoir. In the estuarine reach, downstream the dam, this increasing trend during the low water stage is particularly marked in the middle of the channel. The clay mineral assemblage shows that kaolinite and smectite are the main components, whereas interlayered illite-smectite and illite are minor constituents. The upstream-downstream profile shows a decrease in kaolinite content although it remains the dominant constituent. Floating clay minerals （smectite and illite-smectite） concentrate rather in the middle of the channel and on the right bank where the water depth is higher. According to seasonal variations, the distribution of these clay minerals often follows the concentration of the entire clay fraction; their contents increase during low water stage period. This hydrodynamics sorting of floating minerals, evident in the up-dam zone, tends to disappear in the eastern reach between Diama dam and the mouth. Clay minerals assemblage shows, through the time, a rather homogeneous composition which does not seem to be altered by the seasonal fluctuations.展开更多
基金Under the auspices of the Public Service Department of Malaysia
文摘For the Pinang River, originating in the western highlands of Penang Island, the nature, sources and extent of pollution were studied. The river water samples collected at five selected sites were analyzed for various physical and chemical parameters, namely temperature, DO, BOD, COD, SS, pH, ammoniac nitrogen (AN), and conductance, Long-term data of rainfall and temperature were analyzed to determine the seasonal variations of the streamflow. The streamflow during the dry season is extremely low compared to the wet season, thus concentrations of contaminants derived from point pollution source increase due to lack of rainfall and runoff events. On the contrary, in the predominantly urban and agricultural catchments, non-point pollution source increases during rainy season through seepage and runoff. Effects of seasonal variations consequently determine the quantity and quality of the water parameters. The Jelutong River, the Dondang River and the Air Itam River carry the seepage from widely urban and residential areas to the main Pinang River systems. Water quality of the Pinang River at different points assessed by the water quality indices was compared. According to the quality indices during the study period, water quality in the upper reaches of the river is medium to good. It dwindled in the plains, due to the seepage from urban areas and discharges from the industrial and agricultural lands.
基金Supported by the Fundamental Research Funds for the Central Universities(No.DL11BA20)the GRAP09-Excellent Doctor Paper of Northeast Forestry Universitythe Science and Technology Project of Heilongjiang Province(No.GBQ9C103)
文摘The aim of this study was to determine the phytoplankton community structures of reservoirs of different trophic status, located in a cold region. Physical and chemical variables and the phytoplankton communities were investigated in two reservoirs (Xiquanyan Reservoir and Taoshan Reservoir) in Northeast China in 2009. The two reservoirs showed strong seasonal fluctuations in their physical and chemical composition. Results of the trophic status index indicated that Xiaquanyan Reservoir was mesotrophic, whilst Taoshan Reservoir was eutrophic. Diatoms were the dominant phytoplankton group in Xiquanyan Reservoir throughout all seasons of the study, while in Taoshan Reservoir, diatoms dominated in spring, and cyanobacteria dominated in summer and autumn. This difference was resulted from differences in local environmental factors, including nutrients and hydrology. This study suggests that in mesotrophic reservoirs, nutrients played a key role in controlling seasonal phytoplankton successions, whereas in eutrophic reservoirs water temperature was the key factor in a cold region. Notably, the dominant species in summer in the Taoshan Reservoir was Microcystis, which may produce toxins depending on the ambient conditions, and presenting a risk of local toxin contamination.
文摘Clay fraction contents distribution in the Senegal River estuary after the building of the anti-salt Diama dam has shown that upstream sediments are very muddy. Clay fraction content is as high as 60 % of sediments in the middle of the channel with a pronounced downstream decreasing trend on the banks comparing to the contents in the middle of the channel. Towards the river mouth, the fine fraction tends to disappear leading to a shelly sand sediment type essentially. During low water period, clay fraction contents increase particularly at the vicinity of the dam reservoir. In the estuarine reach, downstream the dam, this increasing trend during the low water stage is particularly marked in the middle of the channel. The clay mineral assemblage shows that kaolinite and smectite are the main components, whereas interlayered illite-smectite and illite are minor constituents. The upstream-downstream profile shows a decrease in kaolinite content although it remains the dominant constituent. Floating clay minerals （smectite and illite-smectite） concentrate rather in the middle of the channel and on the right bank where the water depth is higher. According to seasonal variations, the distribution of these clay minerals often follows the concentration of the entire clay fraction; their contents increase during low water stage period. This hydrodynamics sorting of floating minerals, evident in the up-dam zone, tends to disappear in the eastern reach between Diama dam and the mouth. Clay minerals assemblage shows, through the time, a rather homogeneous composition which does not seem to be altered by the seasonal fluctuations.
