Mechanism of matrix-bound phosphine production in response to atmospheric elevated CO_2 in paddy soils

摘要

To explore the effect of elevated CO2 concentrations ([CO2]) on phosphine formation in paddy fields, the matrix -bound phosphine (MBP) content, different phosphorus fractions and various carbon forms in soil samples from rice cultivation under varying CO2 concentrations of 400 ppm, 550 ppm and 700 ppm by indoor simulation experiment were determined. This study showed that MBP concentration did not increase significantly with elevated [CO2] over four -week cultivation periods of rice seedlings, regardless of soil layers. MBP had a significant positive correlation with total phosphorus (TP) and inorganic phosphorus (IP), and multiple stepwise linear regression analysis further indicated that MBP preservation in neutral paddy soils with depths of 0-20 cm may have been due to conversion from Fe-P and Ca-P. Based on redundancy analysis and forward selection analysis, speculated that the formation of MBP in the neutral paddy soils as the response to atmospheric elevated [CO2] was due to two processes: (i) Fe P transformation affected by the changes of soil respiration (SCO2) and TOC was the main precursor for the production of MBP; and (ii) Ca-P transformation resulting from variation in HCO3- was the secondary MBP source. The complex combination of these two processes is simultaneously controlled by SCO2. In a word, the soil environment in the condition of elevated [CO2] was in favor of MBP storage in neutral paddy soils. The results of our study imply that atmospheric CO2 participates in and has a certain impact on the global biogeochemical cycle of phosphorus. (C) 2018 Elsevier Ltd. All rights reserved.