【摘要】 2004年5月7日至12日在31°~31.8°N、122.5°E以西到海水上溯至0盐度的长江河口进行14个站位叶绿素a浓度的现场观测,其中N1~N3、M1~M3、S1~S3和R6这10个观测站用3条渔船在4天内进行潮周期的涨憩、落急、落憩、涨急、涨憩5个潮时的准同步周日采样观测;对S2、S3、R2、R3、M3、N2和N3这7个位于长江入海口门站位进行表层泥样的叶绿素a浓度观测。结果表明,观测海区表层海水叶绿素a浓度为0.230~11.500μg/dm3,平均值为(1.514±1.712)μg/dm3,高值出现在观测海区东北部的长江冲淡水稀释区,表层海水叶绿素a浓度平面分布从该区的东北部向西南方向逐渐降低,离岸越近叶绿素a浓度越低,低值出现在长江口门内和测区西南部的广阔浑水区域;底层叶绿素a浓度为0.291~2.620μg/dm3,平均值为(1.186±0.531)μg/dm3,其变化幅度与平均浓度均明显低于表层。在涨憩、落急、落憩、涨急和涨憩5个潮周期中水柱平均叶绿素a浓度为1.198~1.910μg/dm3,涨憩和落急潮时,叶绿素a浓度自表层向底层逐渐下降;落憩和涨急潮时,表层的平均叶绿素a浓度略低于中层和底层。2004年春季观测海区叶绿素a浓度与往年夏季和秋季的观测结果相近,但明显高于冬季。表层沉积物叶绿素a浓度为(0.089±0.052)μg/g(湿重),仅占其上方水体平均叶绿素a浓度的极少部分,两者具有良好的相关性。更多还原

【Abstract】 Chlorophyll a concentrations were carried out in 14 stations scattering over the Changjiang River Estuary from May 7th to 12th in 2004.The result shows that the surface chlorophyll a ranges from 0.230 to 11.500 μg/dm3,and the average is(1.514±1.712) μg/dm3 in the surveyed area.The highest chlorophyll a occurs in the northeast of surveyed area of the Changjiang diluted water.It gradually decreases from the northeast to the southwest and the closer to the shore the lower chlorophyll a.The lowest chlorophyll a occurred inside the outlet of the Changjiang River Estuary in the southwest of the surveyed area with muddy water area.The chlorophyll a ranges from 0.291~2.620 μg/dm3 in the bottom water,with an average of(1.186±0.531) μg/dm3.Both of the variation of concentration and average concentration is evidently smaller than that of the surface layer.In the tidal cycle of flood cease,ebb jet,ebb cease,flood jet and flood cease,the average chlorophyll a ranged from 1.198 to 1.910 μg/dm3,in which the concentration at flood cease and ebb jet decreased gradually from the surface to the bottom and the average concentration in surface was a little lower than that of the middle and bottom at ebb cease and flood jet.In the same surveyed area,the average chlorophyll a of water column in spring is(1.357±1.018) μg/dm3,which is almost the same as the observation result in the autumn of 1995(1.322±1.115) μg/dm3,a little higher than that in the summer of 1986(1.244±0.594) μg/dm3 and much higher than that in the winter of 1986(0.254±0.090) μg/dm3.The surface sediment chlorophyll a varied from 0.024 to 0.153 μg/g(wet weight) in 7 stations,with an average value of(0.089±0.052) μg/g.The concentration of the stations located at the outler of the South Branch is(0.133±0.018) μg/g,which is 3 times higher than that at the outlet of North Branch(0.032±0.007) μg/g.As the result of comparing the average chlorophyll a in water columns with than that in the surface sediment,the latter at 6 stations of S2、S3、R3、M3、N2 and N3 accounts for only a little of the former and between them there is good correlation which can be represented as y=5.077 6x+0.812 6 and R2=0.758.更多还原