The relationship between phosphine, methane, and ozone over paddy field in Guangzhou, China

Abstract Greenhouse effect has been attracting more and more attention in the world. Carbon dioxide (CO 2 ) and methane (CH 4 ) are the most important greenhouse gases. Phosphine (PH 3 ) may have a potential greenhouse effect because it can react with hydroxyl radicals (·OH) in competition with other reducing gases. The aim of this study is to discover the relationship among PH 3 , ozone (O 3 ) and CH 4 in paddy fields and estimate the potential greenhouse effect of PH 3 by field experiment. The results reveal that there was a significant negative correlation between O 3 and PH 3 (r = −0.494, p = 0.001, n = 42) during the whole period of rice growth. Similarly, CH 4 was also negatively correlated with PH 3 , but not significant (r = −0.283, p = 0.069, n = 42). However, it was found that PH 3 and CH 4 corresponded to the reciprocal model. These results show that there was a certain competition relationship between PH 3 and CH 4 . It was widely speculated that PH 3 and CH 4 were similar in the photochemical elimination process. ·OH could react with PH 3 , resulting in P H bond break. Then PH 3 was oxidized to phosphate and other oxidation substances. Through Pearson correlation analysis and multiple stepwise linear regression analysis, light intensity was the principal factor affecting PH 3 levels over the paddy field. The regression equation was [PH 3 ] = -0.0003*[L] +20.025 (R 2  = 0.243; F = 5.177; P