The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distributions of these currents, the study area co...The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distributions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus ＂grain size effect＂ is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distribution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution （up to 50%） of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton, after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to particulate organic matter is obviously greater than that to organic matter in sediments in the same place.展开更多
The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field d...The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 ktg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level （including the nutrient supply from the terrestrial runoffs） was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that dia- toms were the main phytoplankton in this area, and Skeletonerna costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends： 1） Skeletonema （mainly S. costatum） was dominant throughout the year; and 2） seasonal succession trends were Coscinodiscus （spring） →Chaetoceros （summer and autumn） → Coscinodiscus （winter）. The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas： average annual phytoplankton biomass and dinoflagellate proportion both presented increased trends during the 1950s - 2000s.展开更多
Through the investigation on radioactive activities of water, sediment and some marine organismsin the Zhujiang Estuary, adjacent sea area and the distributary mouths of the Zhujiang River, activities of total α. rad...Through the investigation on radioactive activities of water, sediment and some marine organismsin the Zhujiang Estuary, adjacent sea area and the distributary mouths of the Zhujiang River, activities of total α. radioactivity, total β radioactivity, artificial radioactive 90Srand 157Cs, and factors inflencing the distribution and the content of U in seawater are studied.The mainly radioactive pollution substances and their sources in the sea area are studied by γ spectra obtained from sediment in the sea area. The results show that the main radioactivity substances are natural radioactivity U,Th series and 40K. which were produced by the modern industry and transported into the sea through the main current of the Zhujiang River.展开更多
利用Ecopath with Ecosim在前期研究的基础上构建了3个时期(2000年秋、2006年秋、2012年秋)长江口水域生态系统的生态通道模型,分析对比了三峡工程蓄水前中后期,长江口水域生态系统结构与能量流动特征。模型将长江口水域生态系统划分为...利用Ecopath with Ecosim在前期研究的基础上构建了3个时期(2000年秋、2006年秋、2012年秋)长江口水域生态系统的生态通道模型,分析对比了三峡工程蓄水前中后期,长江口水域生态系统结构与能量流动特征。模型将长江口水域生态系统划分为鱼类、虾类、蟹类、头足类、底栖动物、浮游动物、浮游植物、碎屑等17个功能组,基本覆盖了长江口生态系统能量流动的主要途径。模型结果分析表明:蓄水前中后期,长江口水域生态系统各功能组营养级组成和分布相近,但由于长江口渔业过度捕捞,蓄水中后期多数功能组的生态营养转换率被动提高。长江口渔获物的组成未发生明显变化,但渔获物的平均营养级降低,渔获量减少。蓄水中后期,生态系统中牧食食物链的重要性增加,碎屑食物链的重要性降低,这与蓄水之后长江入海径流改变、泥沙量减少、陆源污染增加关系密切。结果表明,蓄水前中后期,生态系统均处于不成熟阶段,蓄水后生态系统总生物量、初级生产量及流向碎屑的能量呈降低趋势,但系统的净效率和再循环率升高。展开更多
基金National Basic Research Program of China, No.2002CB412401 National Natural Science Foundation of China, No.40506022+1 种基金 No.40506013 Natural Science Foundation of Jiangsu Province, No.BK2006131
文摘The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distributions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus ＂grain size effect＂ is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distribution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution （up to 50%） of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton, after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to particulate organic matter is obviously greater than that to organic matter in sediments in the same place.
基金the National Basic Research Program of China (Nos. 2001 CB409703 and 2010CB428701)the National Natural Science Foundation of China (Nos. 41140037 and 41276 069)
文摘The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 ktg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level （including the nutrient supply from the terrestrial runoffs） was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that dia- toms were the main phytoplankton in this area, and Skeletonerna costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends： 1） Skeletonema （mainly S. costatum） was dominant throughout the year; and 2） seasonal succession trends were Coscinodiscus （spring） →Chaetoceros （summer and autumn） → Coscinodiscus （winter）. The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas： average annual phytoplankton biomass and dinoflagellate proportion both presented increased trends during the 1950s - 2000s.
文摘Through the investigation on radioactive activities of water, sediment and some marine organismsin the Zhujiang Estuary, adjacent sea area and the distributary mouths of the Zhujiang River, activities of total α. radioactivity, total β radioactivity, artificial radioactive 90Srand 157Cs, and factors inflencing the distribution and the content of U in seawater are studied.The mainly radioactive pollution substances and their sources in the sea area are studied by γ spectra obtained from sediment in the sea area. The results show that the main radioactivity substances are natural radioactivity U,Th series and 40K. which were produced by the modern industry and transported into the sea through the main current of the Zhujiang River.
文摘利用Ecopath with Ecosim在前期研究的基础上构建了3个时期(2000年秋、2006年秋、2012年秋)长江口水域生态系统的生态通道模型,分析对比了三峡工程蓄水前中后期,长江口水域生态系统结构与能量流动特征。模型将长江口水域生态系统划分为鱼类、虾类、蟹类、头足类、底栖动物、浮游动物、浮游植物、碎屑等17个功能组,基本覆盖了长江口生态系统能量流动的主要途径。模型结果分析表明:蓄水前中后期,长江口水域生态系统各功能组营养级组成和分布相近,但由于长江口渔业过度捕捞,蓄水中后期多数功能组的生态营养转换率被动提高。长江口渔获物的组成未发生明显变化,但渔获物的平均营养级降低,渔获量减少。蓄水中后期,生态系统中牧食食物链的重要性增加,碎屑食物链的重要性降低,这与蓄水之后长江入海径流改变、泥沙量减少、陆源污染增加关系密切。结果表明,蓄水前中后期,生态系统均处于不成熟阶段,蓄水后生态系统总生物量、初级生产量及流向碎屑的能量呈降低趋势,但系统的净效率和再循环率升高。
