磷酸盐氧同位素技术在土壤磷循环中的应用

The Application of Phosphate Oxygen Isotopes in Soil Phosphorus Cycling

磷是土壤生态系统中的重要组成元素,开展土壤磷循环研究对提高磷肥利用效率和降低磷的生态环境风险具有重要意义。磷酸盐氧同位素技术已经被证明是一种示踪环境中磷生物地球化学行为的有效方法。本文系统综述了磷酸盐氧同位素技术的研究进展和未来发展方向。详细介绍了磷酸盐氧同位素的技术原理、样品处理和测定方法;阐述了无机磷和有机磷的氧同位素特征及时空分布特征;从评估土壤磷微生物利用状况和示踪土壤磷循环两个方面探讨了磷酸盐氧同位素技术在土壤磷循环研究中的应用前景,分析了磷来源、环境条件、生物活动和样品前处理过程对土壤磷酸盐氧同位素特征的影响,最后展望了该技术未来的研究方向。以期为磷酸盐氧同位素技术在土壤学和环境科学领域的发展和应用提供新的视角和科学指导。

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 systematically described.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.