微藻及其分泌物对溶解性有机磷矿化的促进效应

为较好认识水生态环境中溶解性有机磷(DOP)的矿化过程及其影响因素,本实验选取典型的DOP类型(腺苷-5'-三磷酸二钠盐(ATP)、β-甘油磷酸钠(βP)和D-葡萄糖-6-磷酸二钠盐(GP))、温度(4,15,25℃)、铜绿微囊藻及其分泌物占比(M. a & EPS)(0%、50%、90%)、砷酸盐(As(V))浓度(0,10,100μg/L)4种环境因素,通过L₉(3⁴)正交试验探究影响DOP矿化过程的主要影响因素、水平及矿化过程中的环境变化.结果表明: M. a & EPS作为主要影响因素可显著促进DOP的初期(前2d)矿化,之后被温度取代,温度升高有利于DOP的矿化.典型DOP矿化过程中藻细胞增殖对最佳温度下(25℃)DOP的矿化起促进作用,并使得βP与ATP环境下的pH值和氧化还原电位(ORP)产生较大波动.含As(V)环境中DOP矿化伴随着As(V)形态的转化,GP和ATP环境中均有明显的三价砷(As(III))产生,使得砷的生态风险增强,而温度与M. a & EPS占比增高可促进βP环境中As(V)的甲基化.单独DOP矿化可导致环境中以类蛋白质组分为主的溶解性有机质(DOM)含量显著升高,而存在M. a & EPS时则以可溶性微生物产物类DOM为主.研究结果对认识水体中不同DOP的矿化过程及其可能导致的水华爆发和水环境变化所带来的生态风险的科学管控具有重要意义.

Promoting effect of microalgae and its secretions on dissolved organophosphate mineralization

In order to better understand the mineralization process of dissolved organic phosphorus (DOP) and its related influencing factors in the aquatic ecological environment, the typical DOP types (adenosine-5'-triphosphate disodium salt (ATP), sodium β-glycerophosphoric and D-glucose-6-phosphate disodium salt (GP)), temperatures (4, 15 and 25℃), proportions of Microcystis aeruginosa and its secretions (M. a & EPS) (0%, 50% and 90%), arsenate (As(V)) concentration (0, 10 and 100μg/L) were selected as the main four environmental factors(three levels for each). The L₉(3⁴) orthogonal test was then used to explore the main influencing factors and levels of DOP mineralization process and the main environmental changes during the mineralization process. Results showed that M. a & EPS, as the main influencing factor, could significantly promote the mineralization of DOP at the initial stage (the first 2days), and then was replaced by temperature. Herein the increase of temperature was beneficial to the mineralization of DOP. During the typical DOP mineralization process, the proliferation of algal cells promoted the mineralization of DOP at the optimal temperature(25℃), and caused large fluctuations in pH and ORP in the environment of βP and ATP. The mineralization of DOP in the As(V)-containing environment was accompanied by the transformation of As(V) species. In particular, the production of arsenite (As(III)) was significant in both GP and ATP environments, which could enhance the ecological risk of arsenic. The increased proportion of M. a & EPS promoted the methylation of As(V) in the βP environment. Additionally, the mineralization of individual DOP led to a significant increase in the content of soluble organic matter (DOM) in the environment, which mainly accounted to protein-like components. Meanwhile, the mineralization of DOP combined with M. a & EPS also increased the DOM but with soluble microbial products.The obtain results are of great significance for the comprehensive understanding of the mineralization process of different DOPs in water bodies and the scientific management and control of the ecological risks caused by the outbreak of algal blooms and changes in the water environment.