东湖、汤逊湖和梁子湖沉积物磷形态及pH对磷释放的影响

Phosphorus fractions and the influence of pH on the release of phosphorus from sediments in the Donghu Lake, Tangxun Lake and Liangzi Lake

文章采用淡水沉积物中磷形态标准测试程序（SMT）研究了东湖、汤逊湖和梁子湖沉积物中磷的形态分布,并比较了不同pH条件下沉积物磷释放特征的差异性。结果表明：东湖沉积物总磷质量分数最高,平均值1.232 mg.g-1,其次为汤逊湖（0.762mg.g-1）,梁子湖沉积物总磷质量分数最低（0.572 mg.g-1）;3个湖泊上覆水总磷质量浓度也表现出类似的变化规律,线性相关性分析显示上覆水中总磷质量浓度与沉积物总磷质量分数显著正相关。东湖和梁子湖沉积物总磷中无机磷和有机磷所占比例较接近,汤逊湖无机磷所占比例远低于有机磷。不同湖泊之间磷形态的分布并没有一定的规律性,湖泊的地理分布以及人为因素可能是造成磷形态差异的主要因素。当pH为2.0~7.0时,3个湖泊沉积物中溶解性活性磷（SRP）释放量均呈先增加后减小的趋势;当pH为7.0~12.0时,SRP释放量呈增加趋势。相关分析结果表明,SRP的释放与有机质的质量分数无显著相关性。方差分析结果显示3个湖泊沉积物在黏粒和粉粒组成上均没有显著差异（P〉0.1）,表明实验样品的粒径组成不是造成各个湖泊间磷释放差异的原因。不同pH条件下,SRP释放量与沉积物总磷质量分数显著正相关;酸性环境下,SRP释放量与酸式磷（HCl-P）的相关性优于碱式磷（NaOH-P）,碱性环境下则刚好相反。

The chemical fractions of phosphorus in sediments of Lakes Donghu, Tangxun and Liangzi were investigated using the Standards Measurements and Testing（SMT） extraction procedure, and the release characteristics of phosphorus under different pH conditions were also compared. The results showed that total phosphorus contents in sediment were highest in Lake Donghu, with an average of 1.232 mg·g^-1, followed by Lake Tangxunhu （0.762 mg·g^-1）and Lake Langzihu（0.572 mg·g^-1）. The total phosphorus con- tents in the overlying water demonstrated a similar variation in three lakes and were significantly correlated with the total phosphorus contents of the sediments. The proportions of inorganic and organic phosphorous in the sediments of Lakes Donghu and Langzi were similar, but the proportion of organic phosphorous was higher than that of inorganic phosphorous in the Lake Tangxun. The phos- phorus chemical fractions of sediments in these lakes didn＇t show a certain regularity, and the major factors may be the geographical distribution of the lakes and human factors. When the pH was from 2.0 to 7.0, the release of soluble reactive phosphorus （SRP） from sediments in the three lakes increased firstly, then decreased. When the pH was from 7.0 to 12.0, the release of SRP showed an in- creasing trend. Correlation analysis indicated that the release content of SRP was not significantly correlated with the content of or- ganic matter. The variance analysis showed that there was no significant differences in the sediments composition of clay and silt （P〉0.1）, probably indicating that the different phosphorus release among different lakes was not caused by the particle size of the sample composition. However, correlation analysis indicated that the release content of SRP was significantly correlated with the total phosphorus in sediments, and a marginally significant relationship was found between the HC1 extractable phosphorus （ HC1-P ） content and the release content of SRP under the acid conditions, while an opposite trend was found under the alkaline conditions.