The concentrations and geographical distribution of hexabromocyclododecane （HBCD） were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow ...The concentrations and geographical distribution of hexabromocyclododecane （HBCD） were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection （LOD） to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of t-IBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that y-HBCD dominated in most of the sediment samples, followed by ct- and [3-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.展开更多
The multi-level ditch system developed in the Sanjiang Plain,Northeast China has sped up water drainage process hence transferred more pollutants from farmlands into the rivers of this region.Understanding the seasona...The multi-level ditch system developed in the Sanjiang Plain,Northeast China has sped up water drainage process hence transferred more pollutants from farmlands into the rivers of this region.Understanding the seasonal dynamics of nitrogen (N) and phosphorus (P) transportation in the ditch system and the role of different ditch size is thus crucial for water pollution control of the rivers in the Sanjiang Plain.In this study,an investigation was conducted in the Nongjiang watershed of the Sanjiang Plain to study the nutrient variation and the correlation between water and sediments in the ditch system in terms of ditch level.Water and sediments samples were collected in each ditch level in growing season at regular intervals (once per month),and TN,NO 3--N,NH 4+-N,TP,and PO 4 3--P were analyzed.The results show that nutrient contents in water were higher in June and July,especially in July,the contents of TN and TP were 3.21mg/L and 0.84mg/L in field ditch,4.04mg/L and 1.06mg/L in lateral ditch,2.46mg/L and 0.70mg/L in branch ditch,1.92mg/L and 0.63mg/L in main ditch,respectively.In August and September,the nutrient contents in the water were relatively lower.The peak value of nutrient in ditch water had been moving from the field ditch to the main ditch over time,showing a remarkable impact of ditch system on river water environment.The nutrient transfer in ditch sediments could only be found in rainfall season.Nutrient contents in ditch sediment had effect on that in ditch water,but nutrients in ditch water and sediments had different origination.Ditch management in terms of the key fac-tors is hence very important for protecting river water environment.展开更多
The monitoring work was performed on soil erosion in Lizixi drainage area respectively in 1986 and 1999 by multiple methods with the information extracted from the Landsat TM imagery and Spot imagery. The variation of...The monitoring work was performed on soil erosion in Lizixi drainage area respectively in 1986 and 1999 by multiple methods with the information extracted from the Landsat TM imagery and Spot imagery. The variation of erosion quantity in this area is calculated based on the monitoring result of the erosion intensity and area in these two years. The change of sediment delivery is also analyzed. The research result shows that compared to 1986, in 1999, the erosion area reduced, especially for the area of moderate intensity and above, and the intensity and quantity of erosion decreased. Compared to this period from 1965 to 1986, the sediment delivery ratio has been changed from 0.27 to 0.11 after 1986. The research result could help the decision-making for further water and soil conversation work in Lizixi drainage area, and it also offers reference for monitoring,evaluating and predicting soil erosion in other drainage areas.展开更多
In the present study, five different invert trap configurations （rectangular with and without lids on both sides; trapezoidal, trapezoidal with rectangular base and rectangular with trapezoidal base with lids on both...In the present study, five different invert trap configurations （rectangular with and without lids on both sides; trapezoidal, trapezoidal with rectangular base and rectangular with trapezoidal base with lids on both sides） were simulated for both two-dimensional （2D） and three-dimensional （3D） flow conditions for three sediment types （sand, styrocell and plastic beads） at six flow rates （0.35, 0.70, 1.05, 1.35, 4.55 and 9.95 L/s） for each trap. Computational fluid dynamics （CFD）-based modeling using FLUENT software with Renormalization Group （RNG） k-e model along with discrete phase model （DPM） were used in the simulations. A hexagonal/tetrahedral and map-type non-uniform grid was chosen to discretize the entire computational domain and a control volume finite difference method was used to solve the governing equations. The flow rates selected in the present study cover the entire range of flow rate expected for dry weather and monsoon. The simulation is capable of differentiating between 2D and 3D modeling of particle trajectories, the effects of flow rate and trap geometry on flow patterns developed in the trap. The sediment retention ratio for 2D is higher than that for 3D modeling for all flow conditions, particle types and model geometry due to inclusion of lateral effects in 3D modeling. The invert trap having rectangular shape with trapezoidal base is found to be the most efficient configuration in both 2D and 3D modeling.展开更多
Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River...Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River in relation to natural and human factors in the drainage basin, such as the annual precipitation in different water and sediment source areas, proportion of >0.05 mm sediment of the total sediment load to the lower reaches of Yellow River, the regu-lated degree of the “clear” baseflow from the drainage area above Lanzhou, frequency of hy-perconcentrated flows, area of soil and water conservation measures in the drainage basin. As a result, a multiple regression equation has been established between Fs and 7 influencing factors, with multiple correlation coefficient r = 0.90. The reduction in annual precipitation in different water and sediment source areas has different effects on Fs. The reduction in annual precipitation in the area above Hekou Town and the area between Longmen and Sanmenxia results in a reduction in Fs, but the reduction in annual pre-cipitation in the area between Hekou Town and Longmen results in an increase in Fs. The grain size composition of sediment load strongly affects the Fs; the larger the proportion of >0.05 mm sediment in the suspended sediment load entering the lower reaches of the Yellow River is, the lower the Fs will be. Thus, if the Xiaolangdi Reservoir traps coarse sediment and releases fine sediment, Fs will be enhanced. This study also shows that the lower the proportion of high-flow season river flow to the annual total river flow at Lanzhou Station is, the lower the Fs will be. Therefore, the interception of large quantities of clear water by the reservoirs on the upper reaches of Yellow River is one of the major causes for the decrease in Fs in the lower reaches of the Yellow River.展开更多
基金supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (No.2007BAC27B01)the Young Scientists Fund of the National Natural Science Foundation of China(No.21107121,21107122,20907059)
文摘The concentrations and geographical distribution of hexabromocyclododecane （HBCD） were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection （LOD） to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of t-IBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that y-HBCD dominated in most of the sediment samples, followed by ct- and [3-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.
基金Under the auspices of Major State Basic Research Development Program of China (No.2007CB407307)National Key Technology Research and Development Program of China (No.2006BAC15B01)National Natural Science Foundation of China (No. 40671182)
文摘The multi-level ditch system developed in the Sanjiang Plain,Northeast China has sped up water drainage process hence transferred more pollutants from farmlands into the rivers of this region.Understanding the seasonal dynamics of nitrogen (N) and phosphorus (P) transportation in the ditch system and the role of different ditch size is thus crucial for water pollution control of the rivers in the Sanjiang Plain.In this study,an investigation was conducted in the Nongjiang watershed of the Sanjiang Plain to study the nutrient variation and the correlation between water and sediments in the ditch system in terms of ditch level.Water and sediments samples were collected in each ditch level in growing season at regular intervals (once per month),and TN,NO 3--N,NH 4+-N,TP,and PO 4 3--P were analyzed.The results show that nutrient contents in water were higher in June and July,especially in July,the contents of TN and TP were 3.21mg/L and 0.84mg/L in field ditch,4.04mg/L and 1.06mg/L in lateral ditch,2.46mg/L and 0.70mg/L in branch ditch,1.92mg/L and 0.63mg/L in main ditch,respectively.In August and September,the nutrient contents in the water were relatively lower.The peak value of nutrient in ditch water had been moving from the field ditch to the main ditch over time,showing a remarkable impact of ditch system on river water environment.The nutrient transfer in ditch sediments could only be found in rainfall season.Nutrient contents in ditch sediment had effect on that in ditch water,but nutrients in ditch water and sediments had different origination.Ditch management in terms of the key fac-tors is hence very important for protecting river water environment.
文摘The monitoring work was performed on soil erosion in Lizixi drainage area respectively in 1986 and 1999 by multiple methods with the information extracted from the Landsat TM imagery and Spot imagery. The variation of erosion quantity in this area is calculated based on the monitoring result of the erosion intensity and area in these two years. The change of sediment delivery is also analyzed. The research result shows that compared to 1986, in 1999, the erosion area reduced, especially for the area of moderate intensity and above, and the intensity and quantity of erosion decreased. Compared to this period from 1965 to 1986, the sediment delivery ratio has been changed from 0.27 to 0.11 after 1986. The research result could help the decision-making for further water and soil conversation work in Lizixi drainage area, and it also offers reference for monitoring,evaluating and predicting soil erosion in other drainage areas.
文摘In the present study, five different invert trap configurations （rectangular with and without lids on both sides; trapezoidal, trapezoidal with rectangular base and rectangular with trapezoidal base with lids on both sides） were simulated for both two-dimensional （2D） and three-dimensional （3D） flow conditions for three sediment types （sand, styrocell and plastic beads） at six flow rates （0.35, 0.70, 1.05, 1.35, 4.55 and 9.95 L/s） for each trap. Computational fluid dynamics （CFD）-based modeling using FLUENT software with Renormalization Group （RNG） k-e model along with discrete phase model （DPM） were used in the simulations. A hexagonal/tetrahedral and map-type non-uniform grid was chosen to discretize the entire computational domain and a control volume finite difference method was used to solve the governing equations. The flow rates selected in the present study cover the entire range of flow rate expected for dry weather and monsoon. The simulation is capable of differentiating between 2D and 3D modeling of particle trajectories, the effects of flow rate and trap geometry on flow patterns developed in the trap. The sediment retention ratio for 2D is higher than that for 3D modeling for all flow conditions, particle types and model geometry due to inclusion of lateral effects in 3D modeling. The invert trap having rectangular shape with trapezoidal base is found to be the most efficient configuration in both 2D and 3D modeling.
基金This work was supported by the National Natural Science Foundation of Chinathe Yellow River Water Conservancy Commiss ion(Grant No.50239080)the Major State Basic Research Development Program of China(Grant No.G1999043604).
文摘Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River in relation to natural and human factors in the drainage basin, such as the annual precipitation in different water and sediment source areas, proportion of >0.05 mm sediment of the total sediment load to the lower reaches of Yellow River, the regu-lated degree of the “clear” baseflow from the drainage area above Lanzhou, frequency of hy-perconcentrated flows, area of soil and water conservation measures in the drainage basin. As a result, a multiple regression equation has been established between Fs and 7 influencing factors, with multiple correlation coefficient r = 0.90. The reduction in annual precipitation in different water and sediment source areas has different effects on Fs. The reduction in annual precipitation in the area above Hekou Town and the area between Longmen and Sanmenxia results in a reduction in Fs, but the reduction in annual pre-cipitation in the area between Hekou Town and Longmen results in an increase in Fs. The grain size composition of sediment load strongly affects the Fs; the larger the proportion of >0.05 mm sediment in the suspended sediment load entering the lower reaches of the Yellow River is, the lower the Fs will be. Thus, if the Xiaolangdi Reservoir traps coarse sediment and releases fine sediment, Fs will be enhanced. This study also shows that the lower the proportion of high-flow season river flow to the annual total river flow at Lanzhou Station is, the lower the Fs will be. Therefore, the interception of large quantities of clear water by the reservoirs on the upper reaches of Yellow River is one of the major causes for the decrease in Fs in the lower reaches of the Yellow River.
