不同初始pH下海水中重金属含量变化及其影响因素

摘要

In order to understand the impact of discharging acid seawater from flue gas desulfurization system on heavy metals in natural seawater, the initial pH (pH0) of six groups from 5.0 to 9.0 of seawater were set to investigate the changing characteristics of pH, suspended substance (SS), salinity(S) and heavy metals (Cu, Pb, Zn, Cd, Cr) with the changing of time. With the lapse of investigating time, the pH value in each group increased firstly, decreased slightly in the middle period and kept a relatively steady value in the end. The content of heavy metals and salinity were decreased gradually with the increase of pH, and the content of SS obeyed the reverse changing rule. The photosynthesis of algae was the dominating process for the variation of pH, and pH was the key environmental factor for controlling the content of heavy metals in seawater. Therefore, with the increase of the pH by means of the photosynthesis of acid-resistant algae, a potential means was available to lower heavy metals content and reduce its pollution on natural seawater caused by the discharge of seawater from flue gas desulfurization system.%　　为了解烟气脱硫酸性海水排放对天然海水中重金属的影响，设置初始pH（pH0）分别为5.0、6.5、7.0、7.5、8.0等6个实验组，研究各组海水的pH、盐度、悬浮物以及Cr、Cu、Zn、Cd和Pb等重金属的变化规律。结果表明，随着实验的进行，各实验组水体的 pH 呈现开始升高、中期略降、后期趋稳的变化规律，且 pH0越低，pH增加幅度越大；各实验组的悬浮物含量随pH的升高而增大，重金属含量和盐度均随pH的升高而降低。分析表明，藻类的光合作用是控制水体pH变化的主要过程，pH则是影响水体重金属含量的关键环境因子，符合pH越低、各重金属含量越高的普遍规律。因此，借助耐酸性藻类的光合作用提升水体pH，是减少烟气脱硫海水排放对天然海水中重金属的溶出、减轻重金属污染的可能途径。