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

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。

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

¹⁴³Nd/¹⁴⁴Nd isotope ratio is the key for Sm-Nd isotope method. The ¹⁴³Nd/¹⁴⁴Nd isotope ratio of geological samples varies within a small range, and thus the ¹⁴³Nd/¹⁴⁴Nd isotope ratio analysis must be precise. In order to obtain high precision and high accuracy of the analytical data, the analysis process involving Nd isotope reference material plays an important role. The previous Nd isotope reference material is neodymium oxide, which have been exhausted in recent three decades. A national reference material of ¹⁴³Nd/¹⁴⁴Nd isotope ratio was introduced in this paper, which shows sufficient homogeneity and stability. The certified value of this reference material was determined by eleven participating laboratories using MC-TIMS and MC-ICP-MS. The ¹⁴³Nd/¹⁴⁴Nd isotope ratio value for the reference material is 0.512438, with a combined expanded uncertainty (k=2) of 5 10^-6. The standard solution gets certification in May, 2015 and the Serial number is GSB 04-3258-2015. The standard solution can be used for quality monitoring of the equipment calibration and analysis process during the ¹⁴³Nd/¹⁴⁴Nd ratio determination for geology, resources, ocean, environment, archaeological and other type samples.