[Objectives]This study was conducted to systematically monitor the contents of "three nitrogen",including ammonia nitrogen (NH4^+-N),nitrate nitrogen (NO3^--N) and nitrite nitrogen (NO2^--N) in groundwater i...[Objectives]This study was conducted to systematically monitor the contents of "three nitrogen",including ammonia nitrogen (NH4^+-N),nitrate nitrogen (NO3^--N) and nitrite nitrogen (NO2^--N) in groundwater in Ledong and analyze the reasons.[Methods]A total of 30 sampling points were set up in Ledong,including 22 ground waters and 8 surface waters.NO3^--N,NH4^+-N,NO2^--N and pH indicators were detected.[Results]① There is a problem of excessive nitrogen in the groundwater of Ledong,Hainan.NH4^+-N and NO3^--N exceeded the standards severely,and the over-standard rates were 27.27% and 13.64%,respectively.NO2^--N didn't exceed the standard.Among them,the highest concentration of NH4^+-N was up to 2.692 mg/L;and the highest concentration of NO3^--N reached 24.071 mg/L.② The pollution trends of NH4^+-N and NO2^--N in Ledong County were similar,and NO3^--N had no similarity.③ There was a regional difference in the groundwater three nitrogen in Ledong,Hainan.The pollution level near the farmland was greater than that far from the farmland.The pollution level near the farm area was greater than that far from the farm area.In addition,in combination with the layout of the sampling points and the test results,it was not found that the area far from the coastline would be lower than the area near the coastline in the pollution level.④ The main reasons for the excessive nitrogen in the groundwater of Ledong,Hainan are farmland fertilization,random discharge of domestic sewage,discharge of aquaculture wastewater,and discharge of industrial water at will.[Conclusions]This study is of great significance to safe prevention and control of groundwater in Ledong.展开更多
A survey concerning the concentration of the nutrients in the Three Gorges Reservoir Area was carried out. This paper presents the parameters(NO 3 - N, NO 2 - N, Kjeldahl N, non ionic ammonia, P PO 4 and TP)...A survey concerning the concentration of the nutrients in the Three Gorges Reservoir Area was carried out. This paper presents the parameters(NO 3 - N, NO 2 - N, Kjeldahl N, non ionic ammonia, P PO 4 and TP) determined at 16 sampling sites from 1997 to 1999 The dominant soluble nitrogen form was NO 3 - N followed by Kjeldahl N, NO 2 - N and non ionic ammonia. Mean values of NO 3 - N, NO 2 - N, Kjeldahl N and non ionic ammonia ranged from 0 50 to 2 37 mg/L, 0 022 to 0 084 mg/L, 0 33 to 0 99 mg/L and 0 007 to 0 092 mg/L respectively. Mean values of P PO 4 at most sampling sites were higher than 0 1 mg/L for subject to eutrophication. The major factors influencing the concentrations of N and P might be agricultural runoff, municipal and industrial effluents. In addition, 6 kinds of soil were sampled at the area where would inundated after the dam completed. Two approaches were adopted to simulate the N and P release from the inundated soils. The results showed that the soils would release nitrogen and phosphorus to the overlying water when the soils were inundated. The characteristics of soil affected the equilibrium concentrations of N and P between the soil and the overlying water.展开更多
Non-point-source pollution has become a major threat to the water quality of the Three Gorges Reservoir(TGR);however,nutrient loadings from terrestrial sources are unclear due to a lack of in situ monitoring.A represe...Non-point-source pollution has become a major threat to the water quality of the Three Gorges Reservoir(TGR);however,nutrient loadings from terrestrial sources are unclear due to a lack of in situ monitoring.A representative small watershed in the central part of the TGR area was selected to monitor the loss of nitrogen(N) and phosphorous(P) continuously along with the runoff from 2007 through 2009 to understand the exact sources and loadings.Results show that the non-point-source nitrogen and phosphorus comes mainly from the storm runoff from residential areas,citrus orchards and sloping croplands,which contributes up to 76% of the loadings in this watershed.Thus,a crucial measure for controlling non-point-source pollution is to intercept storm runoff from the three sources.Paddy fields provide a sink for non-point-source N and P by intercepting the runoff and sediment along with their different forms of nitrogen and phosphorus.The N and P removal efficiency by paddy fields from residential areas is within the range of 56% to 98%.Paddy fields are an important land-use option for reducing the non-point-source loading of N and P in the TGR area.展开更多
Eutrophication is recognized as one of the major environmental problems in the Three Gorges Reservoir.Contour hedgerows have been used as a major soil and water conservation measure in this area.Accordingly,a two-year...Eutrophication is recognized as one of the major environmental problems in the Three Gorges Reservoir.Contour hedgerows have been used as a major soil and water conservation measure in this area.Accordingly,a two-year study was conducted to investigate the effects of contour hedgerow intercropping on nutrient loss from sloping farmland in this area.Four treatments were applied:(1) Maize + Soybean,(2) Maize,(3) Maize + Alfalfa,and(4) Maize + Hemerocallis citrina Baroni.Results indicated that nutrient loss in the control treatment(Maize) was serious,especially the average loss flux of total nitrogen(2245.8 mg) and total phosphate(2434.2 mg) in a typical rainfall event.However,the nutrient losses by runoff in the other three treatments with contour hedgerow intercropping showed significant reduction.Compared with the control treatment,the total nitrogen loss in the Alfalfa and Hemerocallis citrina Baroni decreased by 80.9% and 85.0%,respectively,and the total phosphorus loss in the two treatments decreased by 91.2% and 92.5%,respectively.Therefore,it is concluded that nutrient losses could be reduced by using contour hedgerows in the Three Gorges Region.Reducing runoff volume and sediment loss was the main mechanisms of contour hedgerow intercropping to reduce nutrient loss.展开更多
基金Financial support from Training Programs of Innovation and Entrepreneurship for Undergraduates of Hainan Medical University(HYCX2015040)Training Programs of Innovation and Entrepreneurship for Undergraduates of Hainan Province(20160115)
文摘[Objectives]This study was conducted to systematically monitor the contents of "three nitrogen",including ammonia nitrogen (NH4^+-N),nitrate nitrogen (NO3^--N) and nitrite nitrogen (NO2^--N) in groundwater in Ledong and analyze the reasons.[Methods]A total of 30 sampling points were set up in Ledong,including 22 ground waters and 8 surface waters.NO3^--N,NH4^+-N,NO2^--N and pH indicators were detected.[Results]① There is a problem of excessive nitrogen in the groundwater of Ledong,Hainan.NH4^+-N and NO3^--N exceeded the standards severely,and the over-standard rates were 27.27% and 13.64%,respectively.NO2^--N didn't exceed the standard.Among them,the highest concentration of NH4^+-N was up to 2.692 mg/L;and the highest concentration of NO3^--N reached 24.071 mg/L.② The pollution trends of NH4^+-N and NO2^--N in Ledong County were similar,and NO3^--N had no similarity.③ There was a regional difference in the groundwater three nitrogen in Ledong,Hainan.The pollution level near the farmland was greater than that far from the farmland.The pollution level near the farm area was greater than that far from the farm area.In addition,in combination with the layout of the sampling points and the test results,it was not found that the area far from the coastline would be lower than the area near the coastline in the pollution level.④ The main reasons for the excessive nitrogen in the groundwater of Ledong,Hainan are farmland fertilization,random discharge of domestic sewage,discharge of aquaculture wastewater,and discharge of industrial water at will.[Conclusions]This study is of great significance to safe prevention and control of groundwater in Ledong.
文摘A survey concerning the concentration of the nutrients in the Three Gorges Reservoir Area was carried out. This paper presents the parameters(NO 3 - N, NO 2 - N, Kjeldahl N, non ionic ammonia, P PO 4 and TP) determined at 16 sampling sites from 1997 to 1999 The dominant soluble nitrogen form was NO 3 - N followed by Kjeldahl N, NO 2 - N and non ionic ammonia. Mean values of NO 3 - N, NO 2 - N, Kjeldahl N and non ionic ammonia ranged from 0 50 to 2 37 mg/L, 0 022 to 0 084 mg/L, 0 33 to 0 99 mg/L and 0 007 to 0 092 mg/L respectively. Mean values of P PO 4 at most sampling sites were higher than 0 1 mg/L for subject to eutrophication. The major factors influencing the concentrations of N and P might be agricultural runoff, municipal and industrial effluents. In addition, 6 kinds of soil were sampled at the area where would inundated after the dam completed. Two approaches were adopted to simulate the N and P release from the inundated soils. The results showed that the soils would release nitrogen and phosphorus to the overlying water when the soils were inundated. The characteristics of soil affected the equilibrium concentrations of N and P between the soil and the overlying water.
基金supported by the National Science & Technology Pillar Program(Grant No. 2011BAD31B03)the Special Project on Water Pollution Control by the National Science & Technology Pillar Program(Grant No. 2009ZX07104-002)
文摘Non-point-source pollution has become a major threat to the water quality of the Three Gorges Reservoir(TGR);however,nutrient loadings from terrestrial sources are unclear due to a lack of in situ monitoring.A representative small watershed in the central part of the TGR area was selected to monitor the loss of nitrogen(N) and phosphorous(P) continuously along with the runoff from 2007 through 2009 to understand the exact sources and loadings.Results show that the non-point-source nitrogen and phosphorus comes mainly from the storm runoff from residential areas,citrus orchards and sloping croplands,which contributes up to 76% of the loadings in this watershed.Thus,a crucial measure for controlling non-point-source pollution is to intercept storm runoff from the three sources.Paddy fields provide a sink for non-point-source N and P by intercepting the runoff and sediment along with their different forms of nitrogen and phosphorus.The N and P removal efficiency by paddy fields from residential areas is within the range of 56% to 98%.Paddy fields are an important land-use option for reducing the non-point-source loading of N and P in the TGR area.
基金by the National Science & Technology Pillar Program (Grant No. 2009ZX07104-002)the CAS Actionplan for West Development (GrantNo. KZCX2-XB3-09)the Natural Science Foundation of China (Grant No. 40901255)
文摘Eutrophication is recognized as one of the major environmental problems in the Three Gorges Reservoir.Contour hedgerows have been used as a major soil and water conservation measure in this area.Accordingly,a two-year study was conducted to investigate the effects of contour hedgerow intercropping on nutrient loss from sloping farmland in this area.Four treatments were applied:(1) Maize + Soybean,(2) Maize,(3) Maize + Alfalfa,and(4) Maize + Hemerocallis citrina Baroni.Results indicated that nutrient loss in the control treatment(Maize) was serious,especially the average loss flux of total nitrogen(2245.8 mg) and total phosphate(2434.2 mg) in a typical rainfall event.However,the nutrient losses by runoff in the other three treatments with contour hedgerow intercropping showed significant reduction.Compared with the control treatment,the total nitrogen loss in the Alfalfa and Hemerocallis citrina Baroni decreased by 80.9% and 85.0%,respectively,and the total phosphorus loss in the two treatments decreased by 91.2% and 92.5%,respectively.Therefore,it is concluded that nutrient losses could be reduced by using contour hedgerows in the Three Gorges Region.Reducing runoff volume and sediment loss was the main mechanisms of contour hedgerow intercropping to reduce nutrient loss.
