The Response Mechanism Of The Different Phosphorus In The Water Under Physical And Chironomus Plumosus Disturbance

Sediment disturbance is the key factor of the regeneration and transformation ofinternal phosphorus. However, the mechanism of the regeneration and transformation ofinternal phosphorus explained from the point of biological and physical combinationdisturbance is rare. Also,the two parties of combination disturbance could create the effectof mutual promotion and mutual synergy which has a long effect on the transform ofsediment micro-environment and interface, release way and flux of of internal phosphorus.This study focused on the variation law of sediment micro-environment and interface anddifferent forms of phosphorus in the water under the control treatment,biologicaldisturbance treatment and combination disturbance treatment. We tried to reveal thesynergistic effect mechanism of physical and Chironomus plumosus combinationdisturbance on regeneration and transformation of internal phosphorus. Also, we studiedthe response of sediment micro environment and micro interface and different forms ofphosphorus in the water to physical disturbance intensity under the combinationdisturbance. We tried to prove the synergistic effect mechanism of physical andChironomus plumosus combination disturbance on regeneration and transformation ofinternal phosphorus.The results indicated that OPD, TOE, ORP, pH were at high level under thecombination disturbance and higher than those under Chironomus plumosus disturbancetreatment and control treatment. The difference of DO spatial distribution was the mostsignificant, more significant than that under Chironomus plumosus disturbance treatmentand control treatment. Within the6cm sediment under water-sediment interface,the watercontent, porosity and microbial activity of the same depth were at the high level undercombination disturbance, and the gradient of three treatment decreased with the increasingof sediment depth. Also, the phosphorus amount in the overlying water(TP,PP,DTP,DIP)under combination disturbance were higher than that under Chironomus plumosusdisturbance, both were higher than that under control treatment. Also, the decreasing extentand range of DIP and Fe2+in the pore water were greater than those under Chironomusplumosus disturbance treatment and control treatment. The increase of OPD caused bydisturbance mainly contributed to the decrease amount of DIP and Fe2+. The amount ofNH4Cl-P decreased remarkably in the0-2cm sediment while Fe/Al-P increased remarkably.Furthermore, the variation magnitude of NH4Cl-P and Fe/Al-P was highest in three kind oftreatments. The change of the amount of NH4Cl-P is not obvious in the2-4cm sediment while Fe/Al-P increased remarkably. Furthermore, the variation magnitude of Fe/Al-P washighest in three kinds of treatments.The characteristic parameters of sediment micro-environment and interface and theregeneration and transformation of internal phosphorus responded obviously to thephysical disturbance intensity under the combination disturbance. Under the combinationdisturbance, OPD,TOE,ORP,pH,the water content, porosity and microbial activity werepositively correlated with combination disturbance intensity.Under the combinationdisturbance, TP、DTP、DIP、PP in the overlying water were also positively correlated withcombination disturbance intensity. The DIP and Fe2+in the pore water were negativelycorrelated with combination disturbance intensity.Fe/Al-P of the sediment was positivelycorrelated with combination disturbance intensity which contributed to different extent ofspecific adsorption by oxidized FeThe synergistic effect mechanism of physical and Chironomus plumosus combinationdisturbance on regeneration and transformation of internal phosphorus is as follows: firstly,physical disturbance forces Chironomus plumosus to create more and deeper tubes whichwill enhance the effect of bio-irrigation. Secondly,more tubes created by Chironomusplumosus change the water content and porosity of the sediment which will enhance theeffect to the sediment under the same shear force from physical disturbance and in turngreater the effect of bio-irrigation further.