Information about soil nitric oxide （NO） emissions from subtropical forests is quite limited, and even less is known about the pulse emission of NO when wetting soils after a long period of dryness. In this study, w...Information about soil nitric oxide （NO） emissions from subtropical forests is quite limited, and even less is known about the pulse emission of NO when wetting soils after a long period of dryness. In this study, we measured NO fluxes following wetting of dry soft in a broadleaf forest and a pine forest in subtropical China. Large pulses of NO fluxes were observed after soil wetting in both forests. NO fluxes increased significantly within 0.5 h following wetting in both forests and reached peak 1 and 4 h after soil wetting in the pine forest and the broadleaf forest, respectively. In the broadleaf forest, averaged peak flux of NO pulses was 157 ng N m^-2 s^-1, which was 8 times the flux value before wetting, and in the pine forest, the averaged peak flux was 135 ng N m-2 s 1, which was 15.5 times the flux value before wetting. The total pulses-induced NO emissions during the dry season were roughly estimated to be 29.4 mg N m^-2 in the broadleaf forest and 22.2 mg N m^-2 in the pine forest or made up a proportion of 4.6% of the annual NO emission in the broadleaf forest and 5.3% in the pine forest.展开更多
Both Arc GIS 9.2 and ERDAS 9.1 software were used to analyze the concentrations in radiation exposure of marshlands in southern Iraq during June 2009 and January 2010. It was measured radiation exposure rates above th...Both Arc GIS 9.2 and ERDAS 9.1 software were used to analyze the concentrations in radiation exposure of marshlands in southern Iraq during June 2009 and January 2010. It was measured radiation exposure rates above the soil and water surface, and also measured radioactivity in the environmental models （soil, plants, sediment and water） for all the selected sites of the study area. Furthermore, it has＂ been measuring the level of radioactive contamination concentration of the isotope Bi-214 and Ac-228 and K-40 as well as peer-Cs-137-resulting from the operations of nuclear fission and measured the background radiation compared with other regions. Environmental samples （soil-water-plant-deposits） were taken and measuring the concentration ratio of radioisotopes in using the system account gentle rays Kama multi-channel and using the counter--Nal-tinged element--thallium--Type-WIZARD-1470 as well as a LB 1200. The results showed the regions of the marshes of radioactive contamination now.展开更多
Reducing CH4 and N20 emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying （AWD） irrigati...Reducing CH4 and N20 emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying （AWD） irrigation is one promising practice that has been shown to reduce CH4 emissions. However, little is known about the impact of this practice on N20 emissions, in particular under Mediterranean climate. To close this knowledge gap, we assessed how AWD influenced grain yield, fluxes and annual budgets of CH4 and N20 emissions, and global warming potential （GWP） in Italian rice systems over a 2-year period. Overall, a larger GWP was observed under AWD, as a result of high N20 emissions which offset reductions in CH4 emissions. In the first year, with 70% water reduction, the yields were reduced by 33%, CH4 emissions decreased by 97%, while N20 emissions increased by more than 5-fold under AWD as compared to PF; in the second year, with a 40% water saving, the reductions of rice yields and CH4 emissions （13% and 11%, respectively） were not significant, but N20 fluxes more than doubled. The transition from anaerobic to aerobic soil conditions resulted in the highest N20 fluxes under AWD. The duration of flooding, transition to aerobic conditions, water level above the soil surface, and the relative timing between fertilization and flooding were the main drivers affecting greenhouse gas mitigation potential under AWD and should be carefully planned through site-specific management options.展开更多
Intensive management of planted forests may result in soil degradation and decline in timber yield with successive rotations. Biochars may be beneficial for plant production, nutrient uptake and greenhouse gas mitigat...Intensive management of planted forests may result in soil degradation and decline in timber yield with successive rotations. Biochars may be beneficial for plant production, nutrient uptake and greenhouse gas mitigation. Biochar properties vary widely and are known to be highly dependent on feedstocks, but their effects on planted forest ecosystem are elusive. This study investigated the effects of chicken manure biochar, sawdust biochar and their feedstocks on 2-year-old Pinus elliottii growth, fertilizer N use efficiency （NUE）, soil N20 and CH4 emissions, and C storage in an acidic forest soil in a subtropical area of China for one year. The soil was mixed with materials in a total of 8 treatments： non-amended control （CK）; sawdust at 2.16 kg m^-2 （SD）; chicken manure at 1.26 kg m^-2 （CM）; sawdust biochar at 2.4 kg m^-2 （SDB）; chicken manure biochar at 2.4 kg m^-2 （CMB）; 15N-fertilizer alone （10.23 atom% 15N） （NF）; sawdust biochar at 2.4 kg m^-2 plus lSN-fertilizer （SDBN） and chicken manure biochar at 2.4 kg m^-2 plus 15N-fertilizer （CMBN）. Results showed that the CMB treatment increased P. elliottii net primary production （aboveground biomass plus litterfall） and annual net C fixation （ANCF） by about 180% and 157%, respectively, while the the SDB treatment had little effect on P. eUiottii growth. The 15N stable isotope labelling technique revealed that fertilizer NUE was 22.7% in CK, 25.5% in the NF treatment, and 37.0% in the CMB treatment. Chicken manure biochar significantly increased soil pH, total N, total P, total K, available P and available K. Only 2% of the N in chicken manure biochar was available to the tree. The soil N20 emission and CH4 uptake showed no significant differences among the treatments. The apparent C losses from the SD and CM treatments were 35% and 61%, respectively; while those from the CMB and SDB treatments were negligible. These demonstrated that it is crucial to consider biochar properties while evaluating their effects on plant growth and C sequestration.展开更多
The wetted perimeter method(WPM) is used in hydrology and hydraulics to calculate instream flows.The WPM requires few data.It requires only the values of the wetted perimeter,flow and water level,which can be obtained...The wetted perimeter method(WPM) is used in hydrology and hydraulics to calculate instream flows.The WPM requires few data.It requires only the values of the wetted perimeter,flow and water level,which can be obtained from the hydrologic stations of the river in question.In addition,the WPM is not limited by the impacts of human activities on the river runoff.Therefore,this method is generally suitable for the current conditions in China.However,the process of applying the WPM involves two key aspects:how to plot the curve describing the relationship between the wetted perimeter and the discharge and how to confirm the breakpoint of the wetted perimeter-discharge curve.The traditional method is to calculate the curvature or the slope of the wetted perimeter-discharge curve to obtain the minimum flow.According to this method,the minimum flow corresponds to the point of maximum curvature or to the point at which the slope of the curve is equal to 1.The wetted perimeter-discharge curve of a natural river is only part of the complete curve.Thus,the instream flow calculated by the traditional method is the minimum or maximum discharge.The new criterion for defining the breakpoint of the wetted perimeter-discharge curve is that the slope at the breakpoint is a relative maximum,the second-largest slope.The discharges at the breakpoints corresponded to the minimum flow levels required to maintain the ecological function of the river.The minimum instream flow requirements(MIFRs) of four typical reaches,Zhuba,Daofu,Ganzi and Zumuzu hydrological stations on the West Course of the First Stage Project of the South-North Water Transfer Project(WCFSPSNWTP),are calculated using an improved wetted perimeter method(IWPM).The results show that the MIFRs of Zhuba,Daofu,Ganzi and Zumuzu are approximately 9.06-14.5 m 3 s-1,20.7-43.5 m3 s-1,38.8-77.2 m 3 s-1 and 40.4-59.5 m 3 s-1,corresponding to 11.7%-33.9%,14.2%-37.6%,12.4%-28.4% and 17.5%-30.2%,respectively of the annual average flow(AAF).These MIFRs can maintain good ecological function in a river according to the criterion furnished by the Tennant method.展开更多
基金Project supported by the National Key Basic Research and Development Program of China (No. 2002CB410803)
文摘Information about soil nitric oxide （NO） emissions from subtropical forests is quite limited, and even less is known about the pulse emission of NO when wetting soils after a long period of dryness. In this study, we measured NO fluxes following wetting of dry soft in a broadleaf forest and a pine forest in subtropical China. Large pulses of NO fluxes were observed after soil wetting in both forests. NO fluxes increased significantly within 0.5 h following wetting in both forests and reached peak 1 and 4 h after soil wetting in the pine forest and the broadleaf forest, respectively. In the broadleaf forest, averaged peak flux of NO pulses was 157 ng N m^-2 s^-1, which was 8 times the flux value before wetting, and in the pine forest, the averaged peak flux was 135 ng N m-2 s 1, which was 15.5 times the flux value before wetting. The total pulses-induced NO emissions during the dry season were roughly estimated to be 29.4 mg N m^-2 in the broadleaf forest and 22.2 mg N m^-2 in the pine forest or made up a proportion of 4.6% of the annual NO emission in the broadleaf forest and 5.3% in the pine forest.
文摘Both Arc GIS 9.2 and ERDAS 9.1 software were used to analyze the concentrations in radiation exposure of marshlands in southern Iraq during June 2009 and January 2010. It was measured radiation exposure rates above the soil and water surface, and also measured radioactivity in the environmental models （soil, plants, sediment and water） for all the selected sites of the study area. Furthermore, it has＂ been measuring the level of radioactive contamination concentration of the isotope Bi-214 and Ac-228 and K-40 as well as peer-Cs-137-resulting from the operations of nuclear fission and measured the background radiation compared with other regions. Environmental samples （soil-water-plant-deposits） were taken and measuring the concentration ratio of radioisotopes in using the system account gentle rays Kama multi-channel and using the counter--Nal-tinged element--thallium--Type-WIZARD-1470 as well as a LB 1200. The results showed the regions of the marshes of radioactive contamination now.
基金funded by Mars Belgium NV (Mars Food) and Ministero delle Politiche Agrarie, Alimentari e Forestali of Italy (POLORISO project, D.M.5337, Dec.5, 2011)
文摘Reducing CH4 and N20 emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying （AWD） irrigation is one promising practice that has been shown to reduce CH4 emissions. However, little is known about the impact of this practice on N20 emissions, in particular under Mediterranean climate. To close this knowledge gap, we assessed how AWD influenced grain yield, fluxes and annual budgets of CH4 and N20 emissions, and global warming potential （GWP） in Italian rice systems over a 2-year period. Overall, a larger GWP was observed under AWD, as a result of high N20 emissions which offset reductions in CH4 emissions. In the first year, with 70% water reduction, the yields were reduced by 33%, CH4 emissions decreased by 97%, while N20 emissions increased by more than 5-fold under AWD as compared to PF; in the second year, with a 40% water saving, the reductions of rice yields and CH4 emissions （13% and 11%, respectively） were not significant, but N20 fluxes more than doubled. The transition from anaerobic to aerobic soil conditions resulted in the highest N20 fluxes under AWD. The duration of flooding, transition to aerobic conditions, water level above the soil surface, and the relative timing between fertilization and flooding were the main drivers affecting greenhouse gas mitigation potential under AWD and should be carefully planned through site-specific management options.
基金supported by the National Natural Science Foundation of China(No.NFSC-41171191)the Special Agricultural Science and Technology Project of China(No.201503137)+2 种基金the Science and Technology Supporting Project of China(No.2013BAD11B01)the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-EW-409)the Science and Technology Supporting Project of Jiangsu Province,China(No.BE2013451)
文摘Intensive management of planted forests may result in soil degradation and decline in timber yield with successive rotations. Biochars may be beneficial for plant production, nutrient uptake and greenhouse gas mitigation. Biochar properties vary widely and are known to be highly dependent on feedstocks, but their effects on planted forest ecosystem are elusive. This study investigated the effects of chicken manure biochar, sawdust biochar and their feedstocks on 2-year-old Pinus elliottii growth, fertilizer N use efficiency （NUE）, soil N20 and CH4 emissions, and C storage in an acidic forest soil in a subtropical area of China for one year. The soil was mixed with materials in a total of 8 treatments： non-amended control （CK）; sawdust at 2.16 kg m^-2 （SD）; chicken manure at 1.26 kg m^-2 （CM）; sawdust biochar at 2.4 kg m^-2 （SDB）; chicken manure biochar at 2.4 kg m^-2 （CMB）; 15N-fertilizer alone （10.23 atom% 15N） （NF）; sawdust biochar at 2.4 kg m^-2 plus lSN-fertilizer （SDBN） and chicken manure biochar at 2.4 kg m^-2 plus 15N-fertilizer （CMBN）. Results showed that the CMB treatment increased P. elliottii net primary production （aboveground biomass plus litterfall） and annual net C fixation （ANCF） by about 180% and 157%, respectively, while the the SDB treatment had little effect on P. eUiottii growth. The 15N stable isotope labelling technique revealed that fertilizer NUE was 22.7% in CK, 25.5% in the NF treatment, and 37.0% in the CMB treatment. Chicken manure biochar significantly increased soil pH, total N, total P, total K, available P and available K. Only 2% of the N in chicken manure biochar was available to the tree. The soil N20 emission and CH4 uptake showed no significant differences among the treatments. The apparent C losses from the SD and CM treatments were 35% and 61%, respectively; while those from the CMB and SDB treatments were negligible. These demonstrated that it is crucial to consider biochar properties while evaluating their effects on plant growth and C sequestration.
基金supported by the National Natural Science Foundation of China (Grant No. 50809027)the Fundamental Research Funds for the Central Universities (Grant No. 11MG15)the Open Research Fund Program of State Key Laboratory of Water Resources and Hydropower Engineering Science (Grant No. 2009B050)
文摘The wetted perimeter method(WPM) is used in hydrology and hydraulics to calculate instream flows.The WPM requires few data.It requires only the values of the wetted perimeter,flow and water level,which can be obtained from the hydrologic stations of the river in question.In addition,the WPM is not limited by the impacts of human activities on the river runoff.Therefore,this method is generally suitable for the current conditions in China.However,the process of applying the WPM involves two key aspects:how to plot the curve describing the relationship between the wetted perimeter and the discharge and how to confirm the breakpoint of the wetted perimeter-discharge curve.The traditional method is to calculate the curvature or the slope of the wetted perimeter-discharge curve to obtain the minimum flow.According to this method,the minimum flow corresponds to the point of maximum curvature or to the point at which the slope of the curve is equal to 1.The wetted perimeter-discharge curve of a natural river is only part of the complete curve.Thus,the instream flow calculated by the traditional method is the minimum or maximum discharge.The new criterion for defining the breakpoint of the wetted perimeter-discharge curve is that the slope at the breakpoint is a relative maximum,the second-largest slope.The discharges at the breakpoints corresponded to the minimum flow levels required to maintain the ecological function of the river.The minimum instream flow requirements(MIFRs) of four typical reaches,Zhuba,Daofu,Ganzi and Zumuzu hydrological stations on the West Course of the First Stage Project of the South-North Water Transfer Project(WCFSPSNWTP),are calculated using an improved wetted perimeter method(IWPM).The results show that the MIFRs of Zhuba,Daofu,Ganzi and Zumuzu are approximately 9.06-14.5 m 3 s-1,20.7-43.5 m3 s-1,38.8-77.2 m 3 s-1 and 40.4-59.5 m 3 s-1,corresponding to 11.7%-33.9%,14.2%-37.6%,12.4%-28.4% and 17.5%-30.2%,respectively of the annual average flow(AAF).These MIFRs can maintain good ecological function in a river according to the criterion furnished by the Tennant method.
