沉积磷在不同pH水平下的释放与转化规律

为了探讨沉积磷在不同pH条件下的转化及释放行为,有效控制内源磷向水体释放,一定程度上缓解因内源污染导致的水体富营养化问题,采用室内模拟的方法,考察了pH值对沉积物中不同形态磷元素释放与转化的影响.实验研究了在不同pH水平下,沉积物中内源磷的相互转化及向水体释放的总磷(TP)、总溶解磷(TSP)、溶解反应磷(SRP)、总反应磷(TRP)、溶解水解磷(SHP)等5种形态磷的含量.结果表明,受试沉积物样品TP含量为760 mg/kg,属于中等富营养化水平; pH值是影响内源磷释放的重要因素,pH在5～9之间,沉积物中5种形态磷的释放水平较低; 酸性范围内,pH=3的极端酸性条件下,沉积磷释放量最大,在连续38 d的释放时间内,TP最大释放量可达1.47 mg/kg; 在pH=11的极端碱性条件下,能大幅提高沉积磷的释放量,其中TP释放量最高达14.27 mg/kg; 对于同一pH值,除SHP外 ,其余4种形态磷的释放量随时间的变化趋势大体一致,不同pH值对沉积磷形态含量之间的转化影响不明显; SHP受沉积物吸附表面积动态变化影响较明显.

On release and transformation regularity of phosphorus sediment with different pH values

The present paper is dedicated to the investigation and discussion over the release and transformation regularities of the phosphorus sediment when the pH values are different. The purpose of the research is to restrain the inner phosphorus sediment releasing to the water and consequentially alleviate water eutrophication due to the sediment. As is known, it is of great significance to study the transformation and releasing of the content of TP, TSP, SRP, SHP and TRP from the inner phosphorus sediment at different pH values so as to reduce the water pollution. The data gained from our research indicate that the total content of phosphorus sediment sample tested was 760 mg/kg, which is regarded as the mestrophic eutrophic level. Moreover, we have found from experiments that, when the pH value is 5 to 9, the five forms of phosphorus content releasing were fairly low. But, in the acidic range, as the phosphorus release from the sediment becomes high, the total phosphorus content would increase by 1.47 mg/kg during 38 days under the extremely acidic condition with pH value of 11. Moreover, under the extremely alkaline condition of pH value of 11, the phosphorus content release would also be promoted remarkably until the maximum content limit up to 14.27 mg/kg. At the same pH value, however, the relation between the transformations of the five forms except SHP proves to be approxi- mately identical. Therefore, the effect of different pH values on the transformation of the above-said five phosphorus forms seems unapparent, but the dynamic change of sediment exterior area indeed affect the SPH obviously.