好氧不产氧光合细菌反馈作用下的五里峡水库坝前水体化学特征研究

Hydrochemistry Characteristics in front of the Wulixia Reservoir Dam Associated with Feedback from Aerobic Anoxygenic Phototrophic Bacteria

微生物是水体生物地球化学循环的主要驱动者,也是能量代谢的主要参与者,在水体生态系统多样性与稳定性方面发挥着举足轻重的作用。好氧不产氧光合细菌(AAPB)是水体中一类分布广泛的重要功能类群,它们可利用光能补充自身能量代谢,并影响水体化学组分,其重要性被人们广泛认可并深入研究。为探讨岩溶区AAPB反馈作用下的五里峡水库坝前水体化学特征,本文对坝前不同层位水体进行实地监测,在获得不同层位水体溶解有机碳和颗粒有机碳稳定碳同位素特征的基础上,采用荧光定量PCR技术检测、研究了坝前水体不同层位AAPB分布规律。结果表明:取样期五里峡水库坝前水体为HCO_3^--Ca^(2+)-Mg^(2+)贫-中营养型;通过水体溶解氧、δ^(13)CPOC、δ^(13)CDOC和碳氮比综合分析得出,坝前水体有机碳主要由微型生物产生;AAPB占总浮游细菌的相对丰度范围在1.33%~1.60%,且AAPB在不同层位的丰度变化强度要高于总浮游细菌的丰度变化强度,表明相较于总浮游细菌,AAPB对水化学特征的反馈作用更加敏感;使用典范对应分析可揭示水体理化性质与AAPB的内在联系,结果显示AAPB和总浮游细菌均受浊度的影响较大,故基于颗粒沉降的海洋微生物泵作用也适用于陆地岩溶水库。因而,AAPB反馈作用下的水化学特征对揭示CO_2-水-碳酸盐岩-微生物代谢体系具有重要的启示意义。

Micro-organisms are the main drivers of the water biogeochemical cycle and the major player in energy metabolism, which are pivotal processes for maintaining diversity and stability in ecological water systems. Aerobic anoxygenic phototrophic bacteria （AAPB） , the important functional groups widespread in the water, can acquire energy from light and further affect the hydrochemical composition. The importance of AAPB is well recognizedand has been studied extensively. In order to study the relationship between the hydrochemical characteristics and the AAPB feedback effect in front of the Wulixia Reservoir dam, water samples from different layers were collected. Based on the stable carbon isotope of dissolved organic carbon and particulate organic carbon isotope composition, the distribution pattern of AAPB was measured by real-time PCR technology. Results show that the hydrochemical type in the front of the reservoir dam water system was HCO3--Ca2 ＋ -Mg2 ＋ type and had a poor-moderate eutrophication state during the sampling period. The results of dissolved oxygen, stable carbon isotope and the C/N showed that the main source of organic carbon was produced by micro-organisms. The ratio of AAPB to total planktonic bacteria in the Wulixia Reservoir water was 1.33% - 1.60% , and the variation degree of AAPB abundance was greater than that of the total planktonic bacteria abundance, which means that the AAPB feedback is more sensitive to the hydrochemical characteristics compared with that of total planktonic bacteria. The canonical correspondence analysis reveals the relationship between hydrochemical composition and AAPB. Canonical correspondence analysis （CCA） results show that AAPB and total planktonic bacteria are strongly influenced by turbidity, which makes it possible to apply marine microbiological pump theory in karst reservoirs. Hydrochemical characteristic feedback on AAPB will improve understanding of the metabolic system of CO2-H2O-carbonate and micro-organisms.