The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored.Unlike the existing work in detecting early warning signals,this paper presents the most probable trans...The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored.Unlike the existing work in detecting early warning signals,this paper presents the most probable transition paths to characterize the regime shifts.The most probable transition paths are obtained by minimizing the Freidlin-Wentzell(FW)action functional and Onsager-Machlup(OM)action functional,respectively.The most probable path shows the movement trend of the lake eutrophication system under noise excitation,and describes the global transition behavior of the system.Under the excitation of Gaussian noise,the results show that the stability of the eutrophic state and the oligotrophic state has different results from two perspectives of potential well and the most probable transition paths.Under the excitation of Gaussian white noise and periodic force,we find that the transition occurs near the nearest distance between the stable periodic solution and the unstable periodic solution.展开更多
We investigated the patterns of phosphorus transport from purple-soil cropland of 5° and 10° slopes with bare and vegetated surfaces,respectively.Each type of land was tested under a simulated moderate rainf...We investigated the patterns of phosphorus transport from purple-soil cropland of 5° and 10° slopes with bare and vegetated surfaces,respectively.Each type of land was tested under a simulated moderate rainfall of 0.33 mm/min,a downfall of 0.90 mm/min,and a rainstorm of 1.86 mm/min.Runoff dynamics and changes in the export amount of phosphorus are influenced by the rainfall intensity,the slope and surface conditions of cropland.The vegetation diverts rain water from the surface into soil and helps the formation of a subsurface runoff,but has little influence on runoff process at the same sloping degree.Vegetated soil has a smaller phosphorous loss,particularly much less in the particulate form.A heavier rainfall flushes away more phosphorous.Rainwater percolating soil carries more dissolved phosphorous than particulate phosphorous.Understanding the patterns of phosphorous transport under various conditions from purple soil in the middle of Sichuan basin is helpful for developing countermeasures against non-point-source pollution resulting in the eutrophication of water bodies in this region that could,if not controlled properly,deteriorate the water quality of the Three Gorges Reservoir.展开更多
Based on the latest study of phosphate detergent ban and restrict, the phosphorus discharge from detergent in Beijing has been investigated. According to the status of wastewater treatment plants and its practical fun...Based on the latest study of phosphate detergent ban and restrict, the phosphorus discharge from detergent in Beijing has been investigated. According to the status of wastewater treatment plants and its practical function, phosphate-based detergent's contribution to the municipal sewage is calculated to be 8.41%, which is less than the average (20% ) in most other cities of China.展开更多
After the erection of Three-Gorge Reservoir, the water environment in the reservoir area will be turned into water bodies like lakes, and the self-clarification ability of water will also be much slower than ever. Now...After the erection of Three-Gorge Reservoir, the water environment in the reservoir area will be turned into water bodies like lakes, and the self-clarification ability of water will also be much slower than ever. Now, the quality of water in most segments in upper reaches of Yangtze River cannot meet the requirements of l-ll class Environment Quality Standard (GHZB1-1999). In Yangtze River, dialing River and Wujiang River, the main indexes such as colon bacillus, nonionic ammonia, chemical oxygen demand (COD), petroleum, phenol, total phosphorus (TP), heavy metal, etc., have exceeded the standard limits. The water bodies of the reservoir area are facing serious risk of eutrophicationm. To solve that problem, a countermea-sure of multi-spot diverted treatment and separate discharge is recommended. For doing this, lots of small-scale wastewater treatment facilities employing updated activated sludge treatment technologies are to be set up. Up to now, a number of sewage treatment technologies to control eutrophication of water have been developed, which include processes of sequencing batch activated sludge (SBR), absorbing bio-degradation (AB), oxidation channel, package intermittent aeration system (PIAS), intermittent cycle extended aeration system (ICEAS), UNITANK and so on. The Effective one to be applied in the reservoir area should convey the requirements of ecological agriculture, forestry and urban planning, and be accompanied by legal support for appropriate exploitation of natural resources.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12072261 and 11872305)。
文摘The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored.Unlike the existing work in detecting early warning signals,this paper presents the most probable transition paths to characterize the regime shifts.The most probable transition paths are obtained by minimizing the Freidlin-Wentzell(FW)action functional and Onsager-Machlup(OM)action functional,respectively.The most probable path shows the movement trend of the lake eutrophication system under noise excitation,and describes the global transition behavior of the system.Under the excitation of Gaussian noise,the results show that the stability of the eutrophic state and the oligotrophic state has different results from two perspectives of potential well and the most probable transition paths.Under the excitation of Gaussian white noise and periodic force,we find that the transition occurs near the nearest distance between the stable periodic solution and the unstable periodic solution.
基金the Natural Science Foundation of China (No. 40571093)the National Field Station Fund
文摘We investigated the patterns of phosphorus transport from purple-soil cropland of 5° and 10° slopes with bare and vegetated surfaces,respectively.Each type of land was tested under a simulated moderate rainfall of 0.33 mm/min,a downfall of 0.90 mm/min,and a rainstorm of 1.86 mm/min.Runoff dynamics and changes in the export amount of phosphorus are influenced by the rainfall intensity,the slope and surface conditions of cropland.The vegetation diverts rain water from the surface into soil and helps the formation of a subsurface runoff,but has little influence on runoff process at the same sloping degree.Vegetated soil has a smaller phosphorous loss,particularly much less in the particulate form.A heavier rainfall flushes away more phosphorous.Rainwater percolating soil carries more dissolved phosphorous than particulate phosphorous.Understanding the patterns of phosphorous transport under various conditions from purple soil in the middle of Sichuan basin is helpful for developing countermeasures against non-point-source pollution resulting in the eutrophication of water bodies in this region that could,if not controlled properly,deteriorate the water quality of the Three Gorges Reservoir.
文摘Based on the latest study of phosphate detergent ban and restrict, the phosphorus discharge from detergent in Beijing has been investigated. According to the status of wastewater treatment plants and its practical function, phosphate-based detergent's contribution to the municipal sewage is calculated to be 8.41%, which is less than the average (20% ) in most other cities of China.
文摘After the erection of Three-Gorge Reservoir, the water environment in the reservoir area will be turned into water bodies like lakes, and the self-clarification ability of water will also be much slower than ever. Now, the quality of water in most segments in upper reaches of Yangtze River cannot meet the requirements of l-ll class Environment Quality Standard (GHZB1-1999). In Yangtze River, dialing River and Wujiang River, the main indexes such as colon bacillus, nonionic ammonia, chemical oxygen demand (COD), petroleum, phenol, total phosphorus (TP), heavy metal, etc., have exceeded the standard limits. The water bodies of the reservoir area are facing serious risk of eutrophicationm. To solve that problem, a countermea-sure of multi-spot diverted treatment and separate discharge is recommended. For doing this, lots of small-scale wastewater treatment facilities employing updated activated sludge treatment technologies are to be set up. Up to now, a number of sewage treatment technologies to control eutrophication of water have been developed, which include processes of sequencing batch activated sludge (SBR), absorbing bio-degradation (AB), oxidation channel, package intermittent aeration system (PIAS), intermittent cycle extended aeration system (ICEAS), UNITANK and so on. The Effective one to be applied in the reservoir area should convey the requirements of ecological agriculture, forestry and urban planning, and be accompanied by legal support for appropriate exploitation of natural resources.
