浒苔生长-衰亡过程中氮形态的迁移转化过程

针对浒苔氮吸收代谢机制,通过连续培养实验研究浒苔生长-衰亡过程中不同形态氮在藻体和培养液中的分布和迁移.结果表明,浒苔在生长期吸收NO₃^--N（17.37μmol/（g·d））而衰亡期向胞外释放NH₄⁺-N（0.84μmol/（g·d））;在生长期胞内NO₃^--N占无机氮（DIN）73.75%~92.15%,在衰亡期NH₄⁺-N占无机氮60.87%~92.13%;培养液中溶解有机氮（DON）浓度持续增加,其中<1kDa组分占64%~98%,> 1kDa组分占2%~36%.在培养期藻体细胞吸收DIN速率平均为8.96μmol/（g·d）,释放DON的平均迁移速率约为59.57μmol/（g·d）.通过收支模型计算,浒苔将近60% DIN转化为以<1kDa组分占优的DON并分泌到胞外.由此可以推测,近海浒苔爆发可以在月际尺度上对水体生源要素结构产生显著影响.

Transformation and migration of nitrogen forms during the growth-decay of Ulva Prolifera

To investigate the mechanism of nitrogen uptake and metabolism in U. prolifera, the distribution and migration of different forms of nitrogen in culture media and algea cells during the growth-decay process was studied with continuous culture experiments. U. prolifera absorbed NO₃^--N (17.37μmol/(g·d)) into the cell during the growth phase while released NH₄⁺-N (0.84μmol/(g·d)) to the extracellular during the decay phase. In algae cell, up to 73.75%~92.15% of dissolved inorganic nitrogen (DIN) was NO₃^--N during the growth phase, while 60.87%~92.13% was NH₄⁺-N during the decay period. The concentration of dissolved organic nitrogen (DON) in the culture media increased continually during the culture period, with < 1kDa component accounting for 64%~98% and > 1kDa component accounting for 2%~36%. The average migration rate of DIN was about 8.96μmol/(g·d), and the average release rate of DON was about 59.57μmol/(g·d). Nearly 60% DIN was converted into DON and secreted extracellularly, most of which was < 1kDa component. It can be speculated that the outburst of U. prolifera impacts the structure of biological elements significantly on the monthly scale.