浮游植物水华对溶解态铝的清除机制:现场培养结果启示

本文通过现场Al加富培养实验探讨浮游植物细胞生长过程对溶解态Al的清除机制。实验分为4组,分别为对照组,N/P/Si加富组,N/P/Si/Al加富组和沙尘添加组。结果表明:对照组浮游植物细胞的比生长率为0.46d-1,两个营养盐加富组的比生长率增加至0.68d-1,沙尘添加组的比生长率介于两者之间。培养过程中营养盐含量不断下降,直至消耗殆尽。对照组和N/P/Si加富组中溶解态Al浓度缓慢下降,而N/P/Si/Al加富组中溶解态Al的浓度在指数增长期降低约40%,在衰亡期显著回升,沙尘添加组中溶解态Al的浓度随培养时间不断升高。利用草酸盐淋洗试剂区分指数增长期浮游植物细胞中Al的存在形态,对照组"细胞中总Al"和"细胞内结合态Al"的含量分别为(3.6±0.1)mg/g和(2.1±0.3)mg/g,而N/P/Si/Al加富组"细胞中总Al"和"细胞内结合态Al"的含量分别增加至(5.1±0.3)mg/g和(3.2±0.4)mg/g。浮游植物细胞的生长能够显著清除海洋中溶解态Al,其清除机制是细胞内吸收作用为主,细胞外吸附作用为辅。

Scavenging mechanism of dissolved Al by phytoplankton: Inspiration from filed incubation experiments

The scavenging mechanism of dissolved Al by the growth of phytoplankton was investigated through field incubation experiments in the present study. The experiments were allocated into 4 groups: control group, N/P/Si-enrichment group, N/P/Si/Al-enrichment group and dust-enrichment group. The results showed that the phytoplankton cells growth rate of the control group was 0.48 d-1, the two enrichment groups increased to 0.68 d-1, the growth rate of the dust-enrichment group was between them. Nutrients were declining until exhausted in each groups during the incubation period. The concentration of dissolved Al decreased slowly in the control group and N/P/Si-enrichment group. Dissolved Al concentrations decreased 40% during the exponential growth phase of the N/P/Si/Al-enrichment group, and increased during decline phase. The concentration of dissolved Al increased steadily with time in the dust-enrichment group. Total and intra-cellular Al was differentiated using oxalate reagent (Oxalate-EDTA-Citrate). Results showed that the total Al and the intra-cellular Al content in the phytoplankton cells of the control group was (3.6±0.1) mg/g and (2.1±0.3) mg/g, respectively. In the N/P/Si/Al-enrichment group, it was increased to (5.1±0.3) mg/g and (3.2±0.4) mg/g. The growth of phytoplankton can remove dissolved Al in the ocean significantly, and its primary removal mechanism is absorption by phytoplankton cells, supplemented by adsorption by phytoplankton cells.