长江口及邻近海域溶解铋的分布变化特征及影响因素

Distribution of dissolved bismuth in the Yangtze River Estuary and its adjacent waters

利用氢化物发生原子荧光光谱法测定了长江口及邻近海域水体中溶解铋的含量,探讨了海水中溶解铋的分布特征、可能来源及影响因素.结果表明,在表、底两层水体中溶解铋含量分别为0.007—0.086 nmol.L-1和0.007—0.025 nmol.L-1,平均值分别为0.033 nmol.L-1和0.014 nmol.L-1.在空间分布上,表层水体中的溶解铋具有明显的梯度变化,在长江冲淡水所及区域含量较低.而在杭州湾及其同纬度地区的高值区可能是由于钱塘江等河流的输入及海水的平流作用引起.温度和盐度分布特征可以反映研究区域水团输入特征,研究表明,溶解铋含量与盐度呈显著负相关,而与温度呈正相关关系,进一步印证了水团输入对溶解铋空间分布的影响,同时也说明河口地区溶解铋在一定盐度范围内的行为是保守的,在河口地区并未发生明显转移.溶解铋除了受沿岸水体输入影响外,吸附-解吸附过程也是影响其分布的重要因素.研究显示,溶解氧、温度和pH是控制铋在颗粒物中吸附-解吸过程的主要环境因素,它们通过控制溶解度和吸附作用来影响水体中溶解铋的分布和地球化学行为.

Dissolved the method of bismuth concentrations in the Yangtze River Estuary and its adjacent waters were determined lay hydride generation and atomic fluorescence （HG-AFS）. The results showed that Bi concentrations ranged from 0.007 to 0.086 nmol＂ L- 1 in the surface water and from 0. 007 to 0. 025 nmol. L- 1 in the bottom water, with an average of 0. 033 nmol. L-1 and 0. 014 nmol＂ L-1 , respectively. The element varied obviously in the surface water, and was influenced strongly by the freshwater dilution, with lower content found along the Yangtze River diluted water. However, high value of dissolved bismuth was observed in the Hangzhou Bay and neighboring areas at the same latitude ~ indicating the effects of continental runoff and seawater advection. Profile of temperature and salinity can reflect the characteristic of water mass input. Our analysis showed an evldently negative correlation between dissolved bismuth and salinity~ and a positive correlation between Bi concentrations and temperature, which provides additional evidence for the impact of water mass input and also indicates conservative behavior of bismuth within certain range of salinity. Adsorption-desorption processes also substantially impacted the distribution of dissolved bismuth. Our analysis demonstrates DO （dissolved oxygen） , temperature and pH are major environmental factors that control1 the adsorption-desorption behavior of bismuth.