科研之友
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摘要
Phosphorus(P)is an important element in the soil ecosystem. Researching P cycling in soil is of great significance to improve the utilization efficiency of P fertilizer and reduce the ecological environmental risk of P. Using stable isotopes tracer technology to trace P cycling is limited due to its one stable isotope. In the environment, most P exists as phosphate with a stable P-O bond. In the natural ecosystem, without the participation of microorganisms, oxygen isotopic fractionation is slow and negligible. The phosphate oxygen isotopes technique is an effective method for tracing the biogeochemical behavior of P in the environment. This paper systematically reviews the current research and future development of phosphate oxygen isotopes technology. Firstly, the application principle of phosphate oxygen isotopes is introduced. Secondly, the methods for sample extraction, purification and measurement of oxygen isotopic composition of inorganic P and organic P are systematicallydescribed. Modified Hedley sequential extraction is most used in classing the inorganic P form. The organic P is purified by combining size exclusion chromatography and ultraviolet digestion. Thirdly, the characteristics of oxygen isotopic composition and Spatio-temporal distributions of inorganic P and organic P are also described. In general, highly active phosphorus has a higher oxygen isotopic composition which could also fluctuate over time. According to existing reports, there is no spatial variability in soil phosphate oxygen isotopic composition. Fourthly, the application prospect of phosphate oxygen isotopes technique in soil P cycling is discussed from two aspects: (ⅰ)The microbial utilization of soil P can be evaluated according to the balance of phosphate oxygen isotopes composition.(ii)Tracing the soil P cycling basis on the characteristics of oxygen isotopic composition of different P sources and forms. Then, this paper analyses the influencing factors of soil phosphate oxygen isotopic composition. The most important factor is the source of P. Importantly, the exogenous P entering the soil could break the original balance of P cycling, and directly affects the P content and the characteristics of oxygen isotopes. Environmental conditions, including temperature, moisture, pH, oxygen isotopic composition of water also have great impacts on soil phosphate oxygen isotopes. Oxygen isotopic fractionation is mainly driven by organisms, so organisms play an important role in soil P cycling which can be affected by both microbial community and plant diversity. In addition, the processing of samples treatments influence the reliability of the results. Finally, the future research directions of this technology are proposed in three parts: (ⅰ)Establishing standard methods of pretreatment for phosphate oxygen isotopes; (ii)Strengthening the study of organic P oxygen isotopes; (iii)Combining multiple methods to reveal the mechanism of soil P cycling. This paper hopes to provide a new perspective and scientific guidance for the development and application of phosphate oxygen isotopes technique in the field of soil science and environmental science.
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单位中国科学院; 土壤与农业可持续发展国家重点实验室; 中国科学院大学
