The eutrophication of lakes is a global environmental problem.Regulating nitrogen(N)and phosphorus(P)on phytoplankton is considered to be the most important basis of lake eutrophication management.Therefore,the effect...The eutrophication of lakes is a global environmental problem.Regulating nitrogen(N)and phosphorus(P)on phytoplankton is considered to be the most important basis of lake eutrophication management.Therefore,the effects of dissolved inorganic carbon(DIC)on phytoplankton and its role in mitigating lake eutrophication have often been overlooked.In this study,the relationships between phytoplankton and DIC concentrations,carbon isotopic composition,nutrients(N and P),and hydrochemistry in the Erhai Lake(a karst lake)were investigated.The results showed that when the dissolved carbon dioxide(CO_(2)(aq))concentrations in the water were higher than 15μmol/L,the productivity of phytoplankton was controlled by the concentrations of TP and TN,especially by that of TP.When the N and P were sufficient and the CO_(2)(aq)concentrations were lower than 15μmol/L,the phytoplankton productivity was controlled by the concentrations of TP and DIC,especially by that of DIC.Additionally,DIC significantly affected the composition of the phytoplankton community in the lake(p<0.05).When the CO_(2)(aq)concentrations were higher than 15μmol/L,the relative abundance of Bacillariophyta and Chlorophyta was much higher than those of harmful Cyanophyta.Thus,high concentrations of CO_(2)(aq)can inhibit harmful Cyanophyta blooms.展开更多
In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPL...In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. (l)-2-amino-3-(carboxymethylthio)propionic acid was used as the internal standard (I.S.). After a protein precipitation extraction with acetonitrile, dencichine and the I.S. were chromatographed on an Xterra MS-C18 column. The mobile phase was consisted of 20mmol/L ammonium acetate solution-acetonitrile (35:65, V/V) at a flow rate of 0.2 mL/min. The detection was performed on a triple quadrupole mass via electrospray ionization (ESI) source in the positive mode. The intra- and inter-day precision (relative standard deviation, R.S.D.) values of dencichine were below 6.7%. The extraction recoveries were up 85%. The lower limit of quantification was 20 ng/ml, which was sensitive enough to detect the analyte. The HPLC-MS/MS method was successfully applied to the pharmacokinetic study after an intravenous administration of dencichine in Sprague-Dawley (SD) rat.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42130501,42141008,and 41977298)the Strategic Priority Research Program of the Chinese Academy of Science(No.XDB40020000)Special thanks to the Dali Erhai Research Institute for supporting us in sampling Erhai Lake.
文摘The eutrophication of lakes is a global environmental problem.Regulating nitrogen(N)and phosphorus(P)on phytoplankton is considered to be the most important basis of lake eutrophication management.Therefore,the effects of dissolved inorganic carbon(DIC)on phytoplankton and its role in mitigating lake eutrophication have often been overlooked.In this study,the relationships between phytoplankton and DIC concentrations,carbon isotopic composition,nutrients(N and P),and hydrochemistry in the Erhai Lake(a karst lake)were investigated.The results showed that when the dissolved carbon dioxide(CO_(2)(aq))concentrations in the water were higher than 15μmol/L,the productivity of phytoplankton was controlled by the concentrations of TP and TN,especially by that of TP.When the N and P were sufficient and the CO_(2)(aq)concentrations were lower than 15μmol/L,the phytoplankton productivity was controlled by the concentrations of TP and DIC,especially by that of DIC.Additionally,DIC significantly affected the composition of the phytoplankton community in the lake(p<0.05).When the CO_(2)(aq)concentrations were higher than 15μmol/L,the relative abundance of Bacillariophyta and Chlorophyta was much higher than those of harmful Cyanophyta.Thus,high concentrations of CO_(2)(aq)can inhibit harmful Cyanophyta blooms.
文摘In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. (l)-2-amino-3-(carboxymethylthio)propionic acid was used as the internal standard (I.S.). After a protein precipitation extraction with acetonitrile, dencichine and the I.S. were chromatographed on an Xterra MS-C18 column. The mobile phase was consisted of 20mmol/L ammonium acetate solution-acetonitrile (35:65, V/V) at a flow rate of 0.2 mL/min. The detection was performed on a triple quadrupole mass via electrospray ionization (ESI) source in the positive mode. The intra- and inter-day precision (relative standard deviation, R.S.D.) values of dencichine were below 6.7%. The extraction recoveries were up 85%. The lower limit of quantification was 20 ng/ml, which was sensitive enough to detect the analyte. The HPLC-MS/MS method was successfully applied to the pharmacokinetic study after an intravenous administration of dencichine in Sprague-Dawley (SD) rat.
