Oxygen isotope systematics of biologically mediated reactions of phosphate .1. Microbial degradation of organophosphorus compounds
Oxygen isotope systematics of biologically mediated reactions of phosphate .1. Microbial degradation of organophosphorus compounds
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DOI：
10.1016/s0016-7037(97)00272-x
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发表时间：
1997-10-01
影响因子：
5
通讯作者：
Garcia, GA
中科院分区：
文献类型：
--
作者：
Blake, RE;ONeil, JR;Garcia, GA
微生物活动已被用来解释磷矿床以及化石生物磷灰石的氧同位素组成异常。磷酸盐的酶介导反应和微生物介导的有机物降解的实验室实验结果表明，磷酸盐和水之间的氧同位素的显着交换伴随着有机结合的磷酸盐的水解裂解以及无机正磷酸盐的代谢，这是现代孔隙水中溶解磷酸盐再生的重要机制。微生物介导的磷酸盐反应的氧同位素系统学的评价表明，由细菌介导的磷酸盐和水之间的氧同位素交换是由平衡，而不是动力学因素。在某些条件下，微生物介导的交换似乎导致磷酸盐和水之间氧同位素的完全再平衡，在其他情况下，平衡交换可能被来自有机基质的磷酸盐-氧的遗传所掩盖。天然沉积物中类似的微生物过程在溶解磷酸盐向孔隙流体的释放、自生磷灰石的沉淀以及磷块岩矿床和生物磷灰石的成岩蚀变中可能很重要。这些结果具有重要意义的古气候和古环境研究，其中生物源磷酸盐的氧同位素比值被用作古温度指标，以及研究采用磷酸盐氧同位素作为示踪剂的P运输和循环的环境。版权所有（C）1997 Elsevier Science Ltd.
Microbial activity has been invoked to explain anomalous oxygen isotope compositions of phosphate mineral deposits as well as fossil biogenic apatite. Results of laboratory experiments on enzyme-mediated reactions of phosphate and microbially mediated degradation of organic matter, an important mechanism for the regeneration of dissolved phosphate in modern porewaters, demonstrate that significant exchange of oxygen isotopes between phosphate and water accompanies the hydrolytic cleavage of organically bound phosphate as well as the metabolism of inorganic orthophosphate. Evaluation of the oxygen isotope systematics of microbially mediated reactions of phosphate suggests that oxygen isotope exchange between phosphate and water mediated by bacteria is governed by equilibrium rather than kinetic factors. Under certain conditions, the microbially mediated exchange appears to result in complete re-equilibration of oxygen isotopes between phosphate and water and in other instances equilibrium exchange may be masked by inheritance of phosphate-oxygen from the organic substrate. Analogous microbial processes in natural sediments may be important in; the release of dissolved phosphate to pore fluids, precipitation of authigenic apatite, and in the diagenetic alteration of phosphorite deposits and biogenic apatite. These results have important implications for paleoclimatological and paleoenvironmental studies in which oxygen isotope ratios of biogenic phosphate are used as paleotemperature indicators, as well as for studies employing phosphate oxygen isotopes as a tracer of P transport and cycling in the environment. Copyright (C) 1997 Elsevier Science Ltd.