title: Research and application of method of oxygen isotope of inorganic phosphate in Beijing agricultural soils.
abstract: Phosphorus (P) in agricultural ecosystems is an essential and limited element for plants and microorganisms. However, environmental problems caused by P accumulation as well as by P loss have become more and more serious. Oxygen isotopes of phosphate can trace the sources, migration, and transformation of P in agricultural soils. In order to use the isotopes of phosphate oxygen, appropriate extraction and purification methods for inorganic phosphate from soils are necessary. Here, we combined two different methods to analyze the oxygen isotopic composition of inorganic phosphate (δ18OP) from chemical fertilizers and different fractions (Milli-Q water, 0.5 mol L-1NaHCO3(pH = 8.5), 0.1 mol L-1NaOH and 1 mol L-1HCl) of agricultural soils from the Beijing area. The δ18OPresults of the water extracts and NaHCO3extracts in most samples were close to the calculated equilibrium value. These phenomena can be explained by rapid P cycling in soils and the influence of chemical fertilizers. The δ18OPvalue of the water extracts and NaHCO3extracts in some soil samples below the equilibrium value may be caused by the hydrolysis of organic P fractions mediated by extracellular enzymes. The δ18OPvalues of the NaOH extracts were above the calculated equilibrium value reflecting the balance state between microbial uptake of phosphate and the release of intracellular phosphate back to the soil. The HCl extracts with the lowest δ18OPvalues and highest phosphate concentrations indicated that the HCl fraction was affected by microbial activity. Hence, these δ18Opvalues likely reflected the oxygen isotopic values of the parent materials. The results suggested that phosphate oxygen isotope analyses could be an effective tool in order to trace phosphate sources, transformation processes, and its utilization by microorganisms in agricultural soils.
authors.affiliation: Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Liyan
authors.initials: L
authors.lastname: Tian
authors.affiliation: Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing, 100101, China. Guoqj@igsnrr.ac.cn.
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
authors.forename: Yongguan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.
authors.forename: Huijun
authors.initials: H
authors.lastname: He
authors.affiliation: Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, China.
authors.forename: Yunchao
authors.initials: Y
authors.lastname: Lang
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Rongfei
authors.initials: R
authors.lastname: Wei
authors.affiliation: Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Han
authors.affiliation: Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing, 100101, China.
authors.forename: Marc
authors.initials: M
authors.lastname: Peters
authors.affiliation: Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing, 100101, China.
authors.forename: Junxing
authors.initials: J
authors.lastname: Yang
mesh_terms: D000383:Agriculture; D000068476:Beijing; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D010103:Oxygen Isotopes / Q000032:analysis; D010710:Phosphates / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D010103:Oxygen Isotopes; D010710:Phosphates; D012989:Soil Pollutants
keywords: Agricultural soil; Beijing; Different phosphate fractions; Inorganic phosphate; Oxygen isotope