湖泊沉积物溶解性有机氮组分的藻类可利用性

选择乌梁素海和洱海沉积物样品,利用XAD-8树脂分离和三维荧光光谱技术,在室内培养条件下,研究了其溶解性有机氮(DON)不同组分的藻类可利用性.结果表明:①DON分组后,所研究湖泊沉积物DON及DOC平均损失低于5%,即XAD-8树脂分离技术可以用于湖泊沉积物DON的分组研究.②通过三维荧光光谱分析,湖泊沉积物DON亲水组分以类蛋白质为主,疏水组分以类腐殖质为主.③亲水组分培养条件下,来自乌梁素海和洱海沉积物的DON处理,其藻类生长分别呈"S"型曲线和直线上升趋势,最大藻密度分别达到535.5×104个·mL-1和709.5×104个·mL-1;其ρ(DON)均呈显著降低趋势,培养后ρ(DON)分别降低了2.46 mg·L-1和2.98 mg·L-1,表明湖泊沉积物亲水DON组分是藻类可利用的有机氮形态.④疏水组分培养条件下,来自乌梁素海和洱海沉积物的DON处理,其藻类生长均呈"单峰"曲线变化,最大藻密度分别达到113.5×104个·mL-1和275.5×104个·mL-1;ρ(DON)均在培养初期迅速下降,培养后期几乎不变,表明湖泊沉积物疏水DON组分在短时间内藻类可利用性较低,对藻类生长几乎无贡献作用.

Bioavailability of Dissolved Organic Nitrogen Components in the Lake Sediment to Alage

Samples in the sediments of Wuliangsuhai and Erhai Lake were selected, and the technologies of XAD-8 resins separation and three dimensional fluorescence excitation-emission matrix (3DEEM) spectra were applied, in order to study the bioavailability of dissolved organic nitrogen components to alage under the room cultivation. The obtained results showed that: 1Average loss of DON and DOC from sediments was below 5% after dividing DON into different groups,which means the technology of XAD-8 resins separation could be used in the study of DON components in the lake sediment. 2Through 3DEEM analysis, hydrophilic and hydrophobic DON was dominated by protein-like and humic-like materials in the lake sediment,respectively. 3Under the hydrophilic component condition, growth curves of algae tended to show an "S"shape with a straight upward trend in the sediments of Wuliangsuhai and Erhai lake,with the maximum algal density reaching 535.5×10⁴ and 709.5×10⁴ per milliliter,respectively. Meanwhile, the DON concentrations were significantly reduced after cultivation to 2.46 and 2.98 mg·L^-1,respectively,which suggests that hydrophilic DON in the lake sediment was the bioavailable organic nitrogen for alage. 4Under the hydrophbic component conditions,growth curves of algae tended to show a "unimodal" shape in the sediments of Wuliangsuhai and Erhai lake,with the maximum algal density reaching 113.5×10⁴ and 275.5×10⁴ per milliliter,respectively. The DON concentrations were significantly reduced during the early cultivation period,and then kept stable in the late period, which suggests that the hydrophobic DON component bioavailable to alage was low in short term, and the hydrophobic DON component had hardly any positive effect on the growth of algae.