| In this study, the characteristics of organic phosphorus fractions in sediments of seven lakes with different drainage basin feature, ecological structure, and polluted levels from different regions were investigated, and the relationships between organic phosphorus (Po), inorganic phosphorus (Pi) and bioavailable characters were also discussed. The difference of the related content of Po in different sediments indicated the discrepancy of phosphorus sources and biogeochemical cycles in different lakes. Organic matter (OM) was significantly correlated with Po（R>2=0.80，p>＜0.01）, and except for Lake Qilu, OM was significantly correlated with labile Po, moderately labile Po and nonlabile Po in all studied sediments（R>2 were 0.85, 0.52, 0.80 respectively，p>＜0.01）. The moderately labile Po and nonlabile Po were the main fraction of Po in all studied lakes, and the relative contributions to total Po were 15.12%-66.73% and 27.99%-77.72 %, respectively. The mean proportion of labile Po was 6.1% in studied sediments. The rank order of Po fractions was residual Po > HCl-Po > fulvic acid-Po > humic acid-Po > NaHCO3-Po, with mean relative proportion 8.3∶3.1∶2.2∶1.8∶1.0. Labile Po was significantly correlated with total phosphorus (TP), Pi, Po, NaHCO3-Pi and NaOH-Pi. Furthermore, Labile Po was also significantly correlated with T), Po and NaOH-Pi in all studied sediments, which suggested that labile Po was transformed into bioavailable phosphorus and the nonlabile Po may become a potential source of available phosphorus, although it was considered as highly resistant fraction. |
