Spatial-temporal Variation In Nitrogen And Phosphorus Of Wet Deposition And Its Impacts On Water Quality And Primary Productivity

It is important to study the deposition in Lake Taihu watershed and its’impact on the lake ecosystem. This study focuses on the following aspects:monitoring of the wet deposition in six sites around Lake Taihu to detect the changes in the time and space; calculating the deposition rate; using in situ experiment in Meiliang Bay in spring and winter to find the impacts of deposition on water quality and primary production.The results show that (1) the average concentration of TN in wet deposition was3.71mg·L-1, NH4+-N is1.01mg·L-1, NO3--N is1.62mg·L-1;(2) There was a obviously time regular pattern;(3) TN, NH4+-N, NO3--N were dominant nutrients in the lake except the eastern part; TP and DIP were dominated in northern and eastern areas;(4) the deposition rate of TN and NH4+-N was highest in summer, followed by autumn and winter; the deposition rate of NO3--N was highest in summer,followed tby winter and autumn;(5) N deposition was dominated that other nutrients in the wet deposition; P and Si deposition accounted for very small parts;(6) the high concentration of ammonium carried by the rain caused t significant changes in encloses before and after the wet deposition, while stormy wave might promote DSi to release from the sediment. This could be the reason why the concentration of DSi changes significantly in the encloses which is not accepted the wet deposition;(7) There was a remarkable change for primary productivity and its daily variation of primary in the enclosures that was received the wet deposition.