长江口南支水域营养盐和叶绿素a的潮周期变化

VARIATION WITH TIDAL CYCLE OF NUTRIENTS AND CHLOROPHYLL A IN THE SOUTHERN BRANCH OF CHANGJIANG ESTUARY

2007年8月于长江口南支4个站位进行了营养盐和叶绿素a浓度的定点连续观测,结果表明:调查站位的营养盐和叶绿素a浓度垂直变化不大,分层不明显,表中底层平均值的相对标准偏差在0～29.86%之间,且整个潮汛期的变化基本上不具规律性,少数营养盐(如亚硝酸盐和铵盐)呈现出半日周期的变化,即高潮时浓度达到谷值,低潮时浓度出现峰值;位于长江口南支水域南部S2和S4站位的硅酸盐、磷酸盐和硝酸盐在整个潮汛期的平均值都小于北部的S1和S3站位,且S1站位的硅酸盐、磷酸盐和硝酸盐在大小潮之间平均值差异不明显,而S2站位的硅酸盐和硝酸盐大潮时平均值要高于小潮,磷酸盐则相反,此外,S4站位的叶绿素a平均值都大于其他3个站位;4个连续测站的表层叶绿素a浓度与营养盐(NO2--N、PO34--P、SiO23--Si、NO3--N、NH4+-N)相关系数低(-0.6584～0.5494),叶绿素a浓度与营养盐的周日波动相关性不明显;观测区域硅酸盐、磷酸盐、硝酸盐、亚硝酸和铵盐的平均通量分别是238.62、1.36、84.10、1.031、0.55kg.s-1。

Anchor continuously measuring of nutrients and chlorophyll a was carried out in 4 stations in the southern branch of Changiiang Estuary in August, 2007. The results showed that stratification of nutrients and chlorophyll a was not obvious, and relative standard devia- tion of average within tidal phase in 3 water layers changed from zero to 29.86 %, and their intratidal variation did not have a discriminable law except that variation of nitrite and ammo- nium showed a semidiurnal period i. e. that the maxima appeared at low tides, and the mini- ma at high tides; Average of silicate, nitrate and phosphate within tidal phases in southern stations of S2 and S4 was lower than that in northern stations of S1 and S3, and those within spring and neap tides was similar in station of S1, and average of silicate and nitrate in station of 82 within spring tides was higher than those within neap tides, but it was opposite to phosphate, moreover, average of chlorophyll a in station of S4 was higher than other 3 sta- tions. The concentration of chlorophyll a in surface water had little relativity （-0. 6584~0. 5494） with nutrients （NO2-N, PO4^3-P, SiO3^2-Si, NO;-N, and NH＋ N）, so correlation with diel variation of nutrients was not significant. The fluxes of silicon, phosphorus, nitrate, ni- trite and ammonium were 238.62, 1.36, 84.10, 1.031, and 0.55 kg s-1 .