Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and the...Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and their relationship with environmental variables. A total of ten meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, polychaetes, oligochaetes, bivalves, ostracods, cnidarians, turbellarians,tardigrades and other animals. Free-living marine nematodes were the most dominant group in both abundance and biomass. The abundances of marine nematodes were higher in winter and spring than those in summer and autumn. Most of the meiofauna distributed in the 0–2 cm sediment layer. The abundance of meiofauna in hightidal zone was lower than those in low-tidal and mid-tidal zones. Results of correlation analysis showed that Chlorophyll a was the most important factor to influence the seasonal dynamics of the abundance, biomass of meiofauna and abundances of nematodes and copepods. CLUSTER analysis divided the meiofaunal assemblages into three groups and BIOENV results indicated that salinity, concentration of organic matter, sediment sorting coefficient and sediment median diameter were the main environmental factors influencing the meiofaunal assemblages.展开更多
This paper investigates the variability of the break-up dates of the rivers in Northeast China from their icebound states for the period of 1957-2005 and explores some potential explanatory mechanisms. Results show th...This paper investigates the variability of the break-up dates of the rivers in Northeast China from their icebound states for the period of 1957-2005 and explores some potential explanatory mechanisms. Results show that the break-up of the two major rivers (the Heilongjiang River and Songhuajiang River) was about four days earlier, and their freeze-up was about 4-7 days delayed, during 1989 2005 as compared to 1971 1987. This interdecadal variation is evidently associated with the warming trend over the past 50 years. In addition, the break-up and freeze-up dates have large interannual variability, with a standard deviation of about 10-15 days. The break-up date is primarily determined by the January February-March mean surface air temperature over the Siberian-Northeast China region via changes in the melting rate, ice thickness, and snow cover over the ice cover. The interannual variability of the break-up date is also significantly connected with the Northern Annular Mode (NAM), with a correlation coefficient of 0.35-0.55 based on the data from four stations along the two rivers. This relationship is attributed to the fact that the NAM can modulate the East Asian winter monsoon circulation and Siberian-Northeast China surface air temperature in January February-March.展开更多
A buoy of 10 m in diameter was used to record the current speed and direction in a vertical profile in the offshore area of the Changjiang(Yangtze River) Estuary(with an average water depth of 46.0 m) for one year...A buoy of 10 m in diameter was used to record the current speed and direction in a vertical profile in the offshore area of the Changjiang(Yangtze River) Estuary(with an average water depth of 46.0 m) for one year.The results include:(1) the currents rotate clockwise and the current direction is consistent in a vertical profile without clear seasonal variations.(2) The horizontal current speeds are generally high,with a maximum of 128.5 cm/s occurring in summer and 105.5 cm/s appearing in winter commonly close to the surface.The average current speeds in the vertical profile fall in the same range(the differences are less than 8.0 cm/s),with the maximum of47.0 cm/s occurring in summer and 40.8 cm/s in winter.The average current speed during spring tides is twice that during neap tides(26.5 cm/s).(3) Significant differences of speeds are observed in the vertical profile.The maximum current speed occurs at either surface(spring and winter) or sub-surface(summer and autumn),with the minimum current speed appearing at the bottom.The maximum average current speed of all layers is 57.9cm/s,which occurs in the 18-m layer during summer.(4) The average speed of the residual currents ranges from7.5 cm/s to 11.3 cm/s,with the strongest occurring in spring and weakest in winter.The residual currents of all layers are eastward during spring and winter,whereas northeastward or northward during summer and autumn.(5) The currents in the offshore of Changjiang Estuary are impacted collectively by diluted Changjiang River discharge,the Taiwan Warm Current,monsoon and tides.展开更多
基金The National Natural Science Foundation of China under contract No.41576135the Student Research Development Program of Ocean University of China(OUC-SRDP)under contract No.101201051
文摘Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and their relationship with environmental variables. A total of ten meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, polychaetes, oligochaetes, bivalves, ostracods, cnidarians, turbellarians,tardigrades and other animals. Free-living marine nematodes were the most dominant group in both abundance and biomass. The abundances of marine nematodes were higher in winter and spring than those in summer and autumn. Most of the meiofauna distributed in the 0–2 cm sediment layer. The abundance of meiofauna in hightidal zone was lower than those in low-tidal and mid-tidal zones. Results of correlation analysis showed that Chlorophyll a was the most important factor to influence the seasonal dynamics of the abundance, biomass of meiofauna and abundances of nematodes and copepods. CLUSTER analysis divided the meiofaunal assemblages into three groups and BIOENV results indicated that salinity, concentration of organic matter, sediment sorting coefficient and sediment median diameter were the main environmental factors influencing the meiofaunal assemblages.
基金supported by Na-tional Basic Research Program of China (973 Program) under Grant No. 2009CB421406the Chinese Academy of Sciences under Grant KZCX2-YW-Q1-02the Na-tional Natural Science Foundation of China under Grant No. 40631005
文摘This paper investigates the variability of the break-up dates of the rivers in Northeast China from their icebound states for the period of 1957-2005 and explores some potential explanatory mechanisms. Results show that the break-up of the two major rivers (the Heilongjiang River and Songhuajiang River) was about four days earlier, and their freeze-up was about 4-7 days delayed, during 1989 2005 as compared to 1971 1987. This interdecadal variation is evidently associated with the warming trend over the past 50 years. In addition, the break-up and freeze-up dates have large interannual variability, with a standard deviation of about 10-15 days. The break-up date is primarily determined by the January February-March mean surface air temperature over the Siberian-Northeast China region via changes in the melting rate, ice thickness, and snow cover over the ice cover. The interannual variability of the break-up date is also significantly connected with the Northern Annular Mode (NAM), with a correlation coefficient of 0.35-0.55 based on the data from four stations along the two rivers. This relationship is attributed to the fact that the NAM can modulate the East Asian winter monsoon circulation and Siberian-Northeast China surface air temperature in January February-March.
基金The Major State Basic Research Development Program under contract No.2013CB956502the State Key Laboratory of Estuarine and Coastal Research Funds under contract No.SKLEC200906the National Natural Science Foundation of China under contract No.41625021
文摘A buoy of 10 m in diameter was used to record the current speed and direction in a vertical profile in the offshore area of the Changjiang(Yangtze River) Estuary(with an average water depth of 46.0 m) for one year.The results include:(1) the currents rotate clockwise and the current direction is consistent in a vertical profile without clear seasonal variations.(2) The horizontal current speeds are generally high,with a maximum of 128.5 cm/s occurring in summer and 105.5 cm/s appearing in winter commonly close to the surface.The average current speeds in the vertical profile fall in the same range(the differences are less than 8.0 cm/s),with the maximum of47.0 cm/s occurring in summer and 40.8 cm/s in winter.The average current speed during spring tides is twice that during neap tides(26.5 cm/s).(3) Significant differences of speeds are observed in the vertical profile.The maximum current speed occurs at either surface(spring and winter) or sub-surface(summer and autumn),with the minimum current speed appearing at the bottom.The maximum average current speed of all layers is 57.9cm/s,which occurs in the 18-m layer during summer.(4) The average speed of the residual currents ranges from7.5 cm/s to 11.3 cm/s,with the strongest occurring in spring and weakest in winter.The residual currents of all layers are eastward during spring and winter,whereas northeastward or northward during summer and autumn.(5) The currents in the offshore of Changjiang Estuary are impacted collectively by diluted Changjiang River discharge,the Taiwan Warm Current,monsoon and tides.