溶解有机氮组分对莱州湾硅藻-甲藻演变的影响及其动力学研究OA北大核心CSTPCD

Changes in the structure and composition of nutrients can lead to changes in the structure of phytoplankton communities,and differences in nitrogen form composition and nitrogen phosphorus ratio may both lead to changes in phytoplankton populations.Aiming at the potential problem of diatom suc-cession to dinoflagellate dominant populations in Laizhou Bay,the cuthors set up a shore culture experi-ment to study the effects of dissolved organic nitrogen(DON)and its hydrophilic and hydrophobic com-ponents on phytoplankton community structure under different nitrogen phosphorus ratios.The results showed that diatoms(Nitzchia spp.,Chaetoceros compressus,etc.)became dominant algae due to their stronger affinity for dissolved inorganic nitrogen(DIN)(absorption rate constant/semi saturation constant)under experimental conditions without limiting the initial concentration of inorganic nitrogen and phosphorus nutrients.Under high nitrogen phosphorus ratio and hydrophobic DON experimental conditions,dinoflagellates(Alexandrium tamarense)evolved into dominant algae in the late stage of culture due to their stronger affinity for DON.Three-dimensional fluorescence spectroscopy and enzyme activity analysis showed that the hydrophobic component of DON with a high humification index(HIX=1.17)contained a high proportion of humic C peaks(27.0%)and M peaks(16.1%),as well as the slow microbial degradation rate of DON under high nitrogen phosphorus ratio conditions,which were the internal reasons for promoting the growth of dinoflagellate algae using DON humic components as nitrogen sources.The high biological index(BIX=1.29)of the DON hydrophilic component contains a high proportion of protein like absorption peaks T1(42.5%)and B(33.6%),as well as the fast micro-bial degradation rate of DON under low nitrogen phosphorus ratio conditions,which are the internal rea-sons for promoting the growth of diatoms using the DON protein component as a nitrogen source,which is also reflected in the highly active expression of ammonia peptidases in diatoms.