Phosphorus forms in suspended particulate matter of the Yangtze River

Samples of suspended particulate matter were collected from Yangtze River for the period September through October 2006.The phosphorus forms in the suspended particulate matter samples were extracted and examined using the improved technology from the sequential extration method(SEDEX) Ltd.The results show that the authigenic apatite is the dominant form of particulate phosphorus in the Yangtze River.However,the distribution of phosphorus speciation and the primary influential factor appear to be different along the river.From Fuling to Wanzhou,the concentration of detrital fluorapatite phosphorus is high,but the concentration of loosely adsorbed phosphorus and organic phosphorus are low,and the distribution of phosphorus forms is controlled by the amount of suspended particulate matter.In the downstream reach from Xiangxi to Gezhouba,the concentration of loosely adsorbed phosphorus and organic phosphorus are high,the concentration of detrital fluorapatite phosphorus is low,and the contents of phytoplankton and particle sizes in the reach determine the distribution of phosphorus forms.The further downstream reach between Chenglingji to Datong,the concentrations of detrital fluorapatite phosphorus,iron-bound phosphorus and organic phosphorus are high,but loosely adsorbed phosphorus is low.The distribution of phosphorus forms in the reach is affected by the particle size and afflux from the Dongting Lake.The result also shows that the bio-available phosphorus constitutes of 45.56% of all the suspended particulate phosphorus in the Yangtze River.The bio-available phosphorus is more concentrated in downstream reaches than the upstream ones.