The environmental problems in the Bohai Sea have become more serious in the last decade. High nutrient concentration contributes much to it. A Sino-German cooperation program has been carried out to improve the unders...The environmental problems in the Bohai Sea have become more serious in the last decade. High nutrient concentration contributes much to it. A Sino-German cooperation program has been carried out to improve the understanding of the ecosystem by observations and modelling. A three-dimensional ecosystem model, coupled with a physical transport model, is adopted in this study. The simulation for the year 1982 is validated by the data collected in 1982/1983. The simulated annual mean nutrient concentrations are in good agreement with observations. The nutrient concentrations in the Bohai Sea, which are crucial to the algal growth, are high in winter and low in summer. There are depletion from spring to summer and elevation from autumn to winter for nutrients. The nutrients’ depletion is a response to the consumption of the phytoplankton bloom in spring. Internal recycle and external compensation affect the nutrient cycle. Their contributions to the nutrient budgets are discussed based on the simulated results. Production and respiration are the most important sink and source of nutrients. The process of photosynthesis consumes 152 kilotons-P and 831.1 kilotons-N while respiration releases 94.5 kilotons-P and 516.6 kilotons-N in the same period. The remineralization of the detritus pool is an important source of nutrient regene- ration. It can compensate 23 percent of the nutrient consumed by the production process. The inputs of phosphates and nitrogen from rivers are 0.55 and 52.7 kilotons respectively. The net nutrient budget is -3.05 kilotons-P and 31.6 kilotons-N.展开更多
The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model. The influences of the processes (including horizontal advection, river nutrient load,...The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model. The influences of the processes (including horizontal advection, river nutrient load, active transport etc. ) on the phytoplankton biomass and its evolution are estimated. The Bohai Sea is a weak sink of the CO2 in the atmosphere. During the cycle, 13.7% of the gross production of the phytoplankton enter the higher trophic level and 76.8 % of it are consumed by the respiration itself. The nutrient reproduction comes mainly from the internal biogeochemical loop and the rem-ineralization is an important mechanism of the nutrient transfer from organic form to inorganic. Horizontal advection decreases the total biomass and the eutrophication in some sea areas. Change in the nutrient load of a river can only adjust the local system near its estuary. Controlling the input of the nutrient, which limits the alga growth, can be very useful in lessening the phytoplankton biomass.展开更多
In this paper, the combustion characteristics of H2/ AIR premixed gas in microchannels under wall slip boundary conditions were studied. The results show that under the condition of wall slip boundary, the heat transf...In this paper, the combustion characteristics of H2/ AIR premixed gas in microchannels under wall slip boundary conditions were studied. The results show that under the condition of wall slip boundary, the heat transfer between gas and solid wall can be reduced, and the preheating distance of premixed gas to ignition point becomes longer, but the wall heat loss in flame region can also be reduced. However, under the condition of wall slip boundary, the velocity slip and temperature mutation are relatively small. Therefore, the wall slip boundary condition has little influence on the flame combustion characteristics in the microburner.展开更多
In order to explore the composition and metabolic characteristics of functional microorganisms in the extreme environment of fermentation process, lactic acid was used as the sole carbon source in this study, and a st...In order to explore the composition and metabolic characteristics of functional microorganisms in the extreme environment of fermentation process, lactic acid was used as the sole carbon source in this study, and a strain of mold named JP8 was screened from fermented grains with soy sauce flavor. The 18S rDNA of JP8 and similar species were used to construct adjacent trees with MEGA 7.0.26. JP8 was the closest to Galactomyces geotrichum LMA-75, and the 18S rDNA sequence similarity of the two strains reached 99.52%. Therefore, JP8 was named G. geotrichum JP8. The highest growth temperature of JP8 is 35℃, the highest tolerance volume concentration to ethanol is 1.5%, and the highest tolerance volume concentration to lactic acid is 3%. JP8 can still grow well in PDA medium with pH 1. JP8 is fermented in a liquid fermentation medium with lactic acid as the sole carbon source to produce flavor substances such as acetic acid and propylene glycol.展开更多
The delineation of the southern boundary of the latitudinal permafrost in the north of China in the period of late Pleistocene, i.e. the last glaciation maximum (LGM), has been hampered for two reasons. Firstly, previ...The delineation of the southern boundary of the latitudinal permafrost in the north of China in the period of late Pleistocene, i.e. the last glaciation maximum (LGM), has been hampered for two reasons. Firstly, previous studies were limited to the eastern part of the north of China, and,secondly, the ages of the permafrost had not been determined systematically. In this paper, we suggest that the southern boundary of the high latitudinal permafrost in the north ofChina is bounded by approximately 38—40N (eastern part) and 37—39N (western part) lines of latitude based on ourinterpretation of periglacial phenomena and their implica-tion to the environment during the late Pleistocene, and this southern boundary is plotted for the first time. Also, we re-construct the migration of the southern latitudinal perma-frost boundary and the environment after LGM. It is pro-posed that two cold stages occurred in the LGM at 26 kaBP and 23—13 kaBP, when the annual mean temperature was 8—12℃ lower than at present.展开更多
Continuous CO2 flux observation with eddy covariance method conducted in the alpine shrub on the Qinghai-Tibet Plateau indicates that there are distinct diur- nal and monthly variations for CO2 fluxes in the alpine sh...Continuous CO2 flux observation with eddy covariance method conducted in the alpine shrub on the Qinghai-Tibet Plateau indicates that there are distinct diur- nal and monthly variations for CO2 fluxes in the alpine shrub on the plateau. As for diurnal variation, with net CO2 influx from 08:00 to 19:00 and net CO2 efflux from 20:00 to 07:00, peak CO2 flux during warm season (July) appears around 12:00 (?1.19 g CO2·m?2·h?1); there is no obvious horary fluctuation for CO2 flux during cold season (January), and horary CO2 flux during most hours in a day is close to zero except for a small amount of net efflux (about 0.11 g CO2·m?2·h?1) from 11:00—17:00. As for monthly varia- tion, with net CO2 influx from June to September and net CO2 efflux from January to May and October to December, the peak monthly CO2 influx and CO2 efflux appear in Au- gust and April, respectively. The total net CO2 influx from June to September and total net CO2 efflux from February to May and October to December in the alpine shrub on the Qinghai-Tibet Plateau are estimated to be 673 and 446 g CO2·m?2. Results show that the alpine shrub on the Qing- hai-Tibet Plateau is remarkable carbon dioxide sink under no grazing conditions and the total yearly CO2 influx is esti- mated to be 227 g CO2·m?2.展开更多
基金supported by the National Natural Science Foundation of China with Grant(No.G497901001)the Major State Basic Research Program with Grant(No.G1999043703)
文摘The environmental problems in the Bohai Sea have become more serious in the last decade. High nutrient concentration contributes much to it. A Sino-German cooperation program has been carried out to improve the understanding of the ecosystem by observations and modelling. A three-dimensional ecosystem model, coupled with a physical transport model, is adopted in this study. The simulation for the year 1982 is validated by the data collected in 1982/1983. The simulated annual mean nutrient concentrations are in good agreement with observations. The nutrient concentrations in the Bohai Sea, which are crucial to the algal growth, are high in winter and low in summer. There are depletion from spring to summer and elevation from autumn to winter for nutrients. The nutrients’ depletion is a response to the consumption of the phytoplankton bloom in spring. Internal recycle and external compensation affect the nutrient cycle. Their contributions to the nutrient budgets are discussed based on the simulated results. Production and respiration are the most important sink and source of nutrients. The process of photosynthesis consumes 152 kilotons-P and 831.1 kilotons-N while respiration releases 94.5 kilotons-P and 516.6 kilotons-N in the same period. The remineralization of the detritus pool is an important source of nutrient regene- ration. It can compensate 23 percent of the nutrient consumed by the production process. The inputs of phosphates and nitrogen from rivers are 0.55 and 52.7 kilotons respectively. The net nutrient budget is -3.05 kilotons-P and 31.6 kilotons-N.
文摘The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model. The influences of the processes (including horizontal advection, river nutrient load, active transport etc. ) on the phytoplankton biomass and its evolution are estimated. The Bohai Sea is a weak sink of the CO2 in the atmosphere. During the cycle, 13.7% of the gross production of the phytoplankton enter the higher trophic level and 76.8 % of it are consumed by the respiration itself. The nutrient reproduction comes mainly from the internal biogeochemical loop and the rem-ineralization is an important mechanism of the nutrient transfer from organic form to inorganic. Horizontal advection decreases the total biomass and the eutrophication in some sea areas. Change in the nutrient load of a river can only adjust the local system near its estuary. Controlling the input of the nutrient, which limits the alga growth, can be very useful in lessening the phytoplankton biomass.
文摘In this paper, the combustion characteristics of H2/ AIR premixed gas in microchannels under wall slip boundary conditions were studied. The results show that under the condition of wall slip boundary, the heat transfer between gas and solid wall can be reduced, and the preheating distance of premixed gas to ignition point becomes longer, but the wall heat loss in flame region can also be reduced. However, under the condition of wall slip boundary, the velocity slip and temperature mutation are relatively small. Therefore, the wall slip boundary condition has little influence on the flame combustion characteristics in the microburner.
文摘In order to explore the composition and metabolic characteristics of functional microorganisms in the extreme environment of fermentation process, lactic acid was used as the sole carbon source in this study, and a strain of mold named JP8 was screened from fermented grains with soy sauce flavor. The 18S rDNA of JP8 and similar species were used to construct adjacent trees with MEGA 7.0.26. JP8 was the closest to Galactomyces geotrichum LMA-75, and the 18S rDNA sequence similarity of the two strains reached 99.52%. Therefore, JP8 was named G. geotrichum JP8. The highest growth temperature of JP8 is 35℃, the highest tolerance volume concentration to ethanol is 1.5%, and the highest tolerance volume concentration to lactic acid is 3%. JP8 can still grow well in PDA medium with pH 1. JP8 is fermented in a liquid fermentation medium with lactic acid as the sole carbon source to produce flavor substances such as acetic acid and propylene glycol.
文摘The delineation of the southern boundary of the latitudinal permafrost in the north of China in the period of late Pleistocene, i.e. the last glaciation maximum (LGM), has been hampered for two reasons. Firstly, previous studies were limited to the eastern part of the north of China, and,secondly, the ages of the permafrost had not been determined systematically. In this paper, we suggest that the southern boundary of the high latitudinal permafrost in the north ofChina is bounded by approximately 38—40N (eastern part) and 37—39N (western part) lines of latitude based on ourinterpretation of periglacial phenomena and their implica-tion to the environment during the late Pleistocene, and this southern boundary is plotted for the first time. Also, we re-construct the migration of the southern latitudinal perma-frost boundary and the environment after LGM. It is pro-posed that two cold stages occurred in the LGM at 26 kaBP and 23—13 kaBP, when the annual mean temperature was 8—12℃ lower than at present.
基金This work was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KZCX 1-SW-01-01A5 and KZCX1-09-01)State Key Basic Research Plan of China(Grant No.2002CB412501)Priority Areas Program of Northwest Institute of Plateau Biology(Grant No.CXLY-2002-l).
文摘Continuous CO2 flux observation with eddy covariance method conducted in the alpine shrub on the Qinghai-Tibet Plateau indicates that there are distinct diur- nal and monthly variations for CO2 fluxes in the alpine shrub on the plateau. As for diurnal variation, with net CO2 influx from 08:00 to 19:00 and net CO2 efflux from 20:00 to 07:00, peak CO2 flux during warm season (July) appears around 12:00 (?1.19 g CO2·m?2·h?1); there is no obvious horary fluctuation for CO2 flux during cold season (January), and horary CO2 flux during most hours in a day is close to zero except for a small amount of net efflux (about 0.11 g CO2·m?2·h?1) from 11:00—17:00. As for monthly varia- tion, with net CO2 influx from June to September and net CO2 efflux from January to May and October to December, the peak monthly CO2 influx and CO2 efflux appear in Au- gust and April, respectively. The total net CO2 influx from June to September and total net CO2 efflux from February to May and October to December in the alpine shrub on the Qinghai-Tibet Plateau are estimated to be 673 and 446 g CO2·m?2. Results show that the alpine shrub on the Qing- hai-Tibet Plateau is remarkable carbon dioxide sink under no grazing conditions and the total yearly CO2 influx is esti- mated to be 227 g CO2·m?2.
