Advance in the study on phosphorus speciation,transformation and its potential ecological effects in Chinese lakes

Release of phosphorus from sediment of natural waters, especially from those shallow lakes, are essential process in the growth and development of algae bloom. Studies on species transformation and changes in bioavailability will be helpful in understanding geochemical cycling of phosphorus in lakes and its relation to lake eutrophication. This paper summarized the recent research progresses on phosphorus speciation, transformation, phosphorus cycling in Chinese lakes, and the relevant changes in bioavailability. Recently, special attention was given to issues such as different species in sediments in eastern China shallow lakes because there were only a few works on the lakes in the west, south and north of China. Relevant research was also less found on the brackish lakes in the plateaus or lagoons in the estuarine and coastal zones. In addition, it is a pity that no work could make a breakthrough on the methods of phosphorus fractionation. There was a little advance in the study on the transformation of phosphorus species, the assessment of phosphorus release risk and its bioavailability. For example, the pattern of phosphorus release from different types of sediments in response to pH changes was unveiled; the approaches for laboratory and in situ measurements of bioavailable forms of phosphorus were developed, as well as the relationship between acid soluble organic phosphorus species and eutrophication were proposed. In a eutrophic shallow lake, there is an interaction relationship between algal blooms and internal phosphorus release. However, this interaction is well related to human disturbance and influenced by some natural factors, e. g. hydrodynamic processes and stormy waves. Much beneficial exploration was done on the phosphorus speciation, mobilization and transformation between sediment and water interface in many lakes in China, and a lot of hypothesises as well as new methods were also proposed in recent studies, but it still need more experimental data to testify.