The Response Of Size Fraction Phytoplankton To Nitrogen And Phosphorous

Phytoplankton is a key link between material cycle and food chain in the marine ecosystem, it is a very important part in the study of the whole ecological function. So, in this thesis by using different size of filters (2μm filter membrance, 20μm sieve silk, and 200μm sieve silk), Pico-phytoplankton community, Nano- and below it phytoplankton community, Micro- and below it phytoplankton community, and natural community were selected. We studied the response law between different size of phytoplankton communities to phosphate, ammonium nitrogen, nitrate nitrogen, organic nitrogen (urea) respectively, and got the conclusions below:1. The response of different size of phytoplankton to phosphatea. The phosphate transformation process in Pico- water sample is according to the quartic curve, but in Nano- and below it water sample, Micro- and below it water sample, natural communities water sample the phosphate transformation process are all according to the linear function. The phosphate absorbing percentages show as: Pico->natural communities>Micro- and below it>Nano- and bellow it. There aren't significant difference between any two (p>0.05). The phosphate absorbing percentage in high concentration phosphate is significantly lower than in the low concentration phosphate and the medium concentration, and also the difference between any two is much bigger (p<0.01)b. The phosphate absorbing rate in different size of phytoplankton water show as: Pico-0.05).c. All of the phosphate absorption kinetics curves of different size of phytoplankton match the Michaelis-Menten equation, by comparing the parameters of Vm , Kc , Vm / Kc , we get the conclusions: Nano- and below it have the lowest cell nutrition and also need a high phosphate concentration, Micro- and below it have medium cell nutrition, Pico- phytoplankton have the highest cells nutrition, need a low phosphate concentration. Meanwhile, the adaptability of different size of phytoplankton to phosphate show as: Micro- and below it>Nano- and below it>Pico-.d. The concentration of chlorophyl-a in different phytoplankton sample show as: Micro-and below it≈Nano- and below it Nano-and below it>Micro- and below it≈natural communities. There are very significant differences between Pico- and Nano- and below it, Micro- and below it, natural communities respectively (p<0.01). The concentration of chlorophyll a in different ammonium concentration groups show as: control group < low concentration ammonium