Water environmental characteristics, and distribution and the proportion of phosphorus fractions in the sediment cores from the Lake Guozhenghu and Lake Mianhu, sub-lakes of lake Donghu, and Lake Nanhu, in Wuhan regions were analyzed using the seven steps of sequential extraction method. Correlation coefficients among sediment phosphorus forms were also analyzed. The results show that the total phosphorus content of the interstitial water is much higher than that of overlying water in both Lake Guozhenghu and Lake Nanhu, thus there is a strong releasing trend. However, in Lake Miaohu the content of total phosphorus of the interstitial water is lower than that of the overlying water indicating a trend of deposition. In terms of the characteristics of the vertical distribution of phosphorus forms in sediments, we found that these biological activity of phosphorus including Ex-P, AI-P, Fe-P, and Or-P were decreased gradually with the increases of depth. Below 15 cm, the content changed little, while the changes of several relatively inert phosphorus including Oc-P, De-P, ACa-P are not significant with the increase of the depths. The analy- ses of the percentage of different forms of phosphorus, the range of variation in Lake Guozhenghu was bigger than that in Lake Mi- anhu, and the change of Lake Nanhu was biggest among them. By the analysis of correlation coefficients, the increase of total phos- phorus in Lake Guozhenghu mostly came from inorganic phosphorus, and then from the organic phosphorus. While bioavailable phosphorus in inorganic phosphorus was the major reason to the increase of total phosphorus in Lake Miaohu, the contribution of or- ganic phosphorus was not obvious. In Lake Nanhu, both the inorganic phosphorus and organic phosphorus kept a close relationship with the total phosphorus.
Journal of Lake Science