The analysis of 103 samples collected quantitatively from the southern Taiwan Strait (22°4'-24°3'N, 117°'-119°9'E), China, in August 1997 indicates that the abundance of heterotroph...The analysis of 103 samples collected quantitatively from the southern Taiwan Strait (22°4'-24°3'N, 117°'-119°9'E), China, in August 1997 indicates that the abundance of heterotrophic nanoflagellates (HNF) ranges from 391 to 1 846 × 103 cell/dm3, with an average of 949 × 103 cell/dm3, and 96.2% of cells are in size of 2-22 um in all HNF met in the samples. The HNF cells are 9.83-45.79 μg/dm3 after conversion from cell number to carbon content, with an average of 22.82 μg/dm3. The HNF abundance is relatively low in comparison with other areas. The nitrogen and phosphorus nutrients of the water are lower than previous investigations, which may be caused by the El Nino. The biomass of HNF is higher in southern waters, where cell concentration is 3-5 folds higher than that in other waters, and nearly 2-fold as high as the average of the investigated areas. The HNF is mainly habitat in 0-30 m water layer. Both horizontal and vertical HNF distribution must be influenced by hy-drographical dynamic process to a great extent. Continuous in situ observations of HNF indicate the 24 h diurnal rhythm, with two peaks, one in night at one station (Station 9701) and one during the period of 12:00 - 24:00 at another (Station 9704). The factors controlling the diurnal variation of HNF are unclear, although vertical migration of HNF is obviously.展开更多
A seawater sample was analyzed for its lanthanoids (Ln’s) contents by inductively coupled plasma mass spectrometry (ICP-MS). The analytical procedure included the pre-concentration and partial purification of Ln’s w...A seawater sample was analyzed for its lanthanoids (Ln’s) contents by inductively coupled plasma mass spectrometry (ICP-MS). The analytical procedure included the pre-concentration and partial purification of Ln’s with a chelating resin disk and the employment of the combination of the internal standard and standard addition methods in ICP-MS, which seemed indispensable for the determination of low-level Ln’s by ICP-MS. The recoveries of the Ln’s with the disk were mostly 70% or better with the concentration factor of 200. The measured concentrations of Ln’s were on the order of ng?dm<sup>–</sup>3 or lower and reasonable except that of neodymium and samarium.展开更多
With the goal of model fitting species abundance distribution patterns of the tree,shrub and herb layers of the natural Toona ciliata community in Xingdoushan Nature Reserve,Enshi Autonomous Prefecture,Hubei Province,...With the goal of model fitting species abundance distribution patterns of the tree,shrub and herb layers of the natural Toona ciliata community in Xingdoushan Nature Reserve,Enshi Autonomous Prefecture,Hubei Province,we used the data collected from the field survey and employed different ecological niche models.The models tested were the broken stick model(BSM),the overlapping niche model(ONM)and the niche preemption model(NPM),as well as three statistic models,the log-series distribution model(LSD),the log-normal distribution model(LND)and the Weibull distribution model(WDM).To determine the fitted model most suitable to each layer,the fitting effects were judged by criteria of the lowest value of Akaike Information Criterion(AIC),Chi-square and the K-S values with no significant difference(P>0.05)between the theoretical predictions and observed species abundance distribution values.The result showed:(1)The fitting suitability and goodness of fit of the tree,shrub and herb layers by using the three ecological niche models were ranked as:NPM>BSM>ONM.Of the three statistical models,by accepting the fitting results of the three layers,WDM was the best fitting model,followed by LND.By rejecting the fitting tests of the herb layer,LSD had the worst fitting effect.The goodness of the statistical models was ranked as:WDM>LND>LSD.In general,the statistical models had better fitting results than the ecological models.(2)T.ciliata was the dominant species of the tree layer.The species richness and diversity of the herb layer were much higher than those of either the tree layer or the shrub layer.The species richness and diversity of the shrub layer were slightly higher than those of the tree layer.The community evenness accorded to the following order:herb>shrub>tree.Considering the fitting results of the different layers,different ecological niche models or statistical models with optimal goodness of fit and ecological significance can be given priority to in studying the species abundance distribution patterns of T.ciliata communities.展开更多
基金This work was supported by the National Natural Science Foundation of China under contract Nos 49636220 and 49776308.
文摘The analysis of 103 samples collected quantitatively from the southern Taiwan Strait (22°4'-24°3'N, 117°'-119°9'E), China, in August 1997 indicates that the abundance of heterotrophic nanoflagellates (HNF) ranges from 391 to 1 846 × 103 cell/dm3, with an average of 949 × 103 cell/dm3, and 96.2% of cells are in size of 2-22 um in all HNF met in the samples. The HNF cells are 9.83-45.79 μg/dm3 after conversion from cell number to carbon content, with an average of 22.82 μg/dm3. The HNF abundance is relatively low in comparison with other areas. The nitrogen and phosphorus nutrients of the water are lower than previous investigations, which may be caused by the El Nino. The biomass of HNF is higher in southern waters, where cell concentration is 3-5 folds higher than that in other waters, and nearly 2-fold as high as the average of the investigated areas. The HNF is mainly habitat in 0-30 m water layer. Both horizontal and vertical HNF distribution must be influenced by hy-drographical dynamic process to a great extent. Continuous in situ observations of HNF indicate the 24 h diurnal rhythm, with two peaks, one in night at one station (Station 9701) and one during the period of 12:00 - 24:00 at another (Station 9704). The factors controlling the diurnal variation of HNF are unclear, although vertical migration of HNF is obviously.
文摘A seawater sample was analyzed for its lanthanoids (Ln’s) contents by inductively coupled plasma mass spectrometry (ICP-MS). The analytical procedure included the pre-concentration and partial purification of Ln’s with a chelating resin disk and the employment of the combination of the internal standard and standard addition methods in ICP-MS, which seemed indispensable for the determination of low-level Ln’s by ICP-MS. The recoveries of the Ln’s with the disk were mostly 70% or better with the concentration factor of 200. The measured concentrations of Ln’s were on the order of ng?dm<sup>–</sup>3 or lower and reasonable except that of neodymium and samarium.
基金Public Welfare Research Project of Department of Science and Technology in Hubei Province(40 2012DBA40001)Scientific Research Project of Department of Education in Hubei Province(B20160555)
文摘With the goal of model fitting species abundance distribution patterns of the tree,shrub and herb layers of the natural Toona ciliata community in Xingdoushan Nature Reserve,Enshi Autonomous Prefecture,Hubei Province,we used the data collected from the field survey and employed different ecological niche models.The models tested were the broken stick model(BSM),the overlapping niche model(ONM)and the niche preemption model(NPM),as well as three statistic models,the log-series distribution model(LSD),the log-normal distribution model(LND)and the Weibull distribution model(WDM).To determine the fitted model most suitable to each layer,the fitting effects were judged by criteria of the lowest value of Akaike Information Criterion(AIC),Chi-square and the K-S values with no significant difference(P>0.05)between the theoretical predictions and observed species abundance distribution values.The result showed:(1)The fitting suitability and goodness of fit of the tree,shrub and herb layers by using the three ecological niche models were ranked as:NPM>BSM>ONM.Of the three statistical models,by accepting the fitting results of the three layers,WDM was the best fitting model,followed by LND.By rejecting the fitting tests of the herb layer,LSD had the worst fitting effect.The goodness of the statistical models was ranked as:WDM>LND>LSD.In general,the statistical models had better fitting results than the ecological models.(2)T.ciliata was the dominant species of the tree layer.The species richness and diversity of the herb layer were much higher than those of either the tree layer or the shrub layer.The species richness and diversity of the shrub layer were slightly higher than those of the tree layer.The community evenness accorded to the following order:herb>shrub>tree.Considering the fitting results of the different layers,different ecological niche models or statistical models with optimal goodness of fit and ecological significance can be given priority to in studying the species abundance distribution patterns of T.ciliata communities.
