Water samples were collected in 120 stations in the Bohai Sea of China to analyze the distribution of dissolved nutrients and assess the degree of eutrophication in August 2002. The result shows that the average conce...Water samples were collected in 120 stations in the Bohai Sea of China to analyze the distribution of dissolved nutrients and assess the degree of eutrophication in August 2002. The result shows that the average concentration of DIN increased and the PO4-P concentration sharply decreased compared to the previous data of corresponding period. The high concentrations of DIN and PO4-P occurred in coastal waters, especially in the bays and some river estuaries, while the high concentrations of SiO3-Si in the surface and middle depth occurred in the central area of the Bohai Sea. The average ratio of DIN/PO4-P was much higher than the Redfield Ratio （16：1）. Apparently, PO4-P was one of the limiting nutrient for phytoplankton growing in the sea. The average concentrations of DON and DOP were higher than their inorganic forms. The results of eutrophication assessment show that 22.1% of all stations were classified as violating the concentration levels of the National Seawater Quality Standard （GB 3097-1997） for DIN and only 3.9% for PO4-R The average eutrophication index in the overall area was 0.21±0.22 and the high values occurred in Bohai Bay, Liaodong Bay and near the Yellow River estuary. This means that the state of eutrophication was generally mesotrophic in the Bohai Sea, but relatively worse in the bays, especially some river estuaries.展开更多
In this research, the main purpose is to estimate the variation of PM2.5 mass concentration and study the influence of meteorological characteristics on major components of PM2.5 concentrations in urban Tokyo, Japan. ...In this research, the main purpose is to estimate the variation of PM2.5 mass concentration and study the influence of meteorological characteristics on major components of PM2.5 concentrations in urban Tokyo, Japan. The results shown that the annual mean mass concentration of PM2.5 in urban Tokyo was higher than JEQS （Japanese Environmental Quality Standard） of the MOEJ （Ministry of the Environment Japan） （15 μg/m^3）, and 41.1% of the daily PM2.5 mass concentration exceeded the annual JEQS concentration during observation period. The major components of PM2.5 including SO4^2-, NO3^-, NH4^＋, OC and EC were tightly related to the meteorological conditions, the correlations results shown that the wind speed and relative humidity had significant correlations with major components of PM2.5 than the other meteorological factors. Higher relative humidity, windless and less rainfall conditions were favorable for elimination of PM2.5 concentration. Higher temperature was beneficial to the formation of SO42＂, but higher temperature and stronger sunshine duration were not conducive to the formation of NO3^-.展开更多
In this paper we propose a possible explanation to the Fermion mass hierarchy problem by fitting the type-II seesaw mechanism into the Higgs doublet sector, such that their vacuum expectation values are hierarchal. We...In this paper we propose a possible explanation to the Fermion mass hierarchy problem by fitting the type-II seesaw mechanism into the Higgs doublet sector, such that their vacuum expectation values are hierarchal. We extend the Standard Model with two extra Higgs doublets as well as a spontaneously broken U X(1) gauge symmetry. All the fermion Yukawa couplings except that of the top quark are of O(10^(-2)) in our model. Constraints on the parameter space of the model from low energy processes are studied. Besides, the lightest one of the neutral fermion fields, which is introduced to cancel the anomalies of the U(1)X gauge symmetry can be the cold dark matter candidate. We investigate its signature in the dark matter direct detection.展开更多
基金Supported by the National Natural Science Foundation of China (No. 40136020)Key International Technology Cooperation Plan (No. 2004DFA03600)the National Basic Research Program of China (973 Program, No. 2005CB422305)
文摘Water samples were collected in 120 stations in the Bohai Sea of China to analyze the distribution of dissolved nutrients and assess the degree of eutrophication in August 2002. The result shows that the average concentration of DIN increased and the PO4-P concentration sharply decreased compared to the previous data of corresponding period. The high concentrations of DIN and PO4-P occurred in coastal waters, especially in the bays and some river estuaries, while the high concentrations of SiO3-Si in the surface and middle depth occurred in the central area of the Bohai Sea. The average ratio of DIN/PO4-P was much higher than the Redfield Ratio （16：1）. Apparently, PO4-P was one of the limiting nutrient for phytoplankton growing in the sea. The average concentrations of DON and DOP were higher than their inorganic forms. The results of eutrophication assessment show that 22.1% of all stations were classified as violating the concentration levels of the National Seawater Quality Standard （GB 3097-1997） for DIN and only 3.9% for PO4-R The average eutrophication index in the overall area was 0.21±0.22 and the high values occurred in Bohai Bay, Liaodong Bay and near the Yellow River estuary. This means that the state of eutrophication was generally mesotrophic in the Bohai Sea, but relatively worse in the bays, especially some river estuaries.
文摘In this research, the main purpose is to estimate the variation of PM2.5 mass concentration and study the influence of meteorological characteristics on major components of PM2.5 concentrations in urban Tokyo, Japan. The results shown that the annual mean mass concentration of PM2.5 in urban Tokyo was higher than JEQS （Japanese Environmental Quality Standard） of the MOEJ （Ministry of the Environment Japan） （15 μg/m^3）, and 41.1% of the daily PM2.5 mass concentration exceeded the annual JEQS concentration during observation period. The major components of PM2.5 including SO4^2-, NO3^-, NH4^＋, OC and EC were tightly related to the meteorological conditions, the correlations results shown that the wind speed and relative humidity had significant correlations with major components of PM2.5 than the other meteorological factors. Higher relative humidity, windless and less rainfall conditions were favorable for elimination of PM2.5 concentration. Higher temperature was beneficial to the formation of SO42＂, but higher temperature and stronger sunshine duration were not conducive to the formation of NO3^-.
基金Supported in part by the Wisconsin Alumni Research Foundation
文摘In this paper we propose a possible explanation to the Fermion mass hierarchy problem by fitting the type-II seesaw mechanism into the Higgs doublet sector, such that their vacuum expectation values are hierarchal. We extend the Standard Model with two extra Higgs doublets as well as a spontaneously broken U X(1) gauge symmetry. All the fermion Yukawa couplings except that of the top quark are of O(10^(-2)) in our model. Constraints on the parameter space of the model from low energy processes are studied. Besides, the lightest one of the neutral fermion fields, which is introduced to cancel the anomalies of the U(1)X gauge symmetry can be the cold dark matter candidate. We investigate its signature in the dark matter direct detection.
