Abstract: Recently, environmental pollution caused by phosphorus (P) loss has become an increasingly serious problem. Therefore, it is significant to identify the sources, migration and transformation of P in the environment. The oxygen isotope composition of phosphate (δ¹⁸O_P) represents a powerful tracer, which has been widely used for investigations of aquatic ecosystems, soils and paleoenvironments. This article discusses the δ¹⁸O_P composition of natural substances and related fractionation mechanisms as well as the separation and purification of phosphate from environmental samples and introduces the application of δ¹⁸O_P analyses in environmental science. According to the progress and problems of previous research, some modifications and improvements should be put forward for future studies: The methods of separating and purifying of δ¹⁸O_P should be selected according to the sample properties; fractionation mechanisms and applied prospects of δ¹⁸O_P in environment need to be further studied.

Key words: Yunnan Province, flue-cured tobacco, reference crop evapotranspiration, water requirement, irrigation requirement index, climatic change.