Regeneration And Transformation Of BAPP Under Sediment Repeated Disturbance Conditions

Sediment disturbance has significant influence on phosphorus (P) migration andtransformation at sediment-water interface. However, the information about the effect ofbioavailable particulate phosphorus under sediment disturbance conditions on thedevelopment process of waterbody eutrophication is limited. It is important to research themigration and transformation of bioavailable phosphorus and sedimentary phosphorus andthe contribution of different forms of phosphorus in sediments to bioavailable particulatephosphorus, in order to explain the mechanism on the development process of waterbodyeutrophication. In the article, the bioavailable phosphorus migration in overlying water andthe transformation of phosphorus forms in the sediments and the relationship between itstransformation and bioavailable particulate phosphorus under sediment disturbanceconditions were investigated. These will provide beneficial references to explain themechanism on the development process of waterbody eutrophication under the conditionsof sediment disturbance.The results show that the distribution of different forms of phosphorus (TP, DTP, DIP)in overlying water were significantly changed under long-term repeated disturbanceconditions, the concentrations of TP, DTP, DIP in the overlying water decreased in thespring, and at the end of the experiment were lower than the static conditions. It isindicating that repeated disturbance promotes the different forms of phosphorus in theoverlying water migration to the sediments. However, the concentrations of TP in theoverlying water showed increasing trend in the summer and autumn, DTP and DIP showeda gradually decreasing trend. All This might be attributed to the growth of algae.Short-time repeated disturbance help to decrease the concentrations of TP, DTP, DIP in theoverlying water, DIP, DTP showed first increased and then decreased under the every timerepeated disturbance conditions, but with the increase in the number of distrurbances, theincrements of DIP and DTP gradually decreased. In addition, the percentage of AAP ofDTP in the overlying water gradually decreased with the increase in the number ofdisturbances. Under sediment resuspension conditions with the addition of algae, theconcentrations of DTP and DIP in the overlying water showed decreased after the firstincrease, and under sediment resuspension conditions, the concentrations of DTP and DIPin the overlying water were not increased after every time disturbance, but decreased withthe number of disturbances increased. It is indicating that there is an inherent link between disturbance with migration and transformation of endogenous phosphorus, and repeateddisturbance helps decrease the bioavailability of DTP.There was the close relationship between phosphorus forms in sediments and theseasons. Under long-term repeated disturbance conditions, the Ca-P in the sediments ofspring increased gradually. While, the Ca-P in the sediments of summer and autumndecreased gradually. Under repeated disturbance conditions, the Ca-P in the sediments ofspring, summer and autumn significantly were higher than the static conditions. In addition,under sediment resuspension conditions without the addition of algae, the Ca-P increasedafter slightly decreased, and under sediment resuspension conditions with the addition ofalgae, the Ca-P decreased gradually, and the concentrations of algae in the overlying waterincreased significantly. It is syggesting that part of Ca-P belong to biological phosphorus,and repeated disturbance promote the transformation of other forms of phosphorus insediments to Ca-P. In addition, under long-term repeated disturbance conditions, the Res-Pin the sediments of summer and autumn increments were larger and higher than the staticconditions. Unlike the static conditions, under sediment resuspension conditions with andwithout the addition of algae conditions, the Res-P increased gradually, and sedimentresuspension conditions with the addition of algae conditions were higher than sedimentresuspension conditions without the addition of algae. It is suggesting that algae may bebeneficial to the transformation of other forms of phosphorus in the sediment to Res-P, andexhanced phosphorus fixation capacity of sediment.Under long-term repeated sediment disturbance conditions, the concentrations BAP inthe overlying water of spring, summer and autumn gradually decreased in the entireprocess of experiment, and the decrement under repeated disturbance was higher than thestatic conditions. It is suggesting that repeated disturbance promoted BAP in the overlyingwater to migrate to the sediments, or transformed to other forms of phosphorus. Undershort-term repeated disturbance conditions, the concentrations of BAPP increased and thenincreased with the number of disturbances increased. In addition, the concentrations ofBAPP was significantly higher than the sum of AAP and NH4Cl-P, and BAPP has a goodcorrelation with Ca-P, and second only to the correlation coefficient of AAP in thesuspension solids and BAPP. It is suggesting that the BAPP is composed of80%of AAPand NH4Cl-P. It is problematic to estimate the BAPP using the mobile phosphorus forms,such as NH4Cl-P, non-occluded Fe/Al-P. Some refractory forms of phosphorus, such asCa-P may also be used by algae, and Ca-P has a significant contribution to BAPP.