Bioavailability of organic phosphorus in the water level fluctuation zone soil and the effects of ultraviolet irradiation on it in the Three Gorges Reservoir, China

• Published in: The Science of the total environment 2020-10, Vol.738, p.139912-139912, Article 139912
• Main Authors: Gao, Jun-min, Chen, Zhu-man, Wang, Chao, Fang, Fang, Huang, Jun-jie, Guo, Jin-song
• Format: Article
• Language: English
• Subjects: Bioavailability; Enzymatic hydrolysis; Organic phosphorus; Ultraviolet light; Water level fluctuation zone
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.139912

Ultraviolet (UV) irradiation is an abiotic pathway for the transformation of complex phosphorus (P) components into inorganic P in ecosystems. To explore the effect of UV irradiation on organic P (OP) bioavailability in the water level fluctuation zone (WLFZ) soil, we collected representative soil samples from WLFZ of the Pengxi River, a tributary of the TGR, China. We determined the contents of different forms of OP in the WLFZ soil through sequential extraction. The bioavailability of different forms of OP and the effect of UV light were characterised using a combination of enzymatic hydrolysis and UV irradiation. The OP contents of the different extracts (Po) were ranked as NaOH-Po > NaHCO3-Po > H2O-Po, whereas those of enzymatically hydrolysable organic P (EHP) were ranked as NaOH-EHP > NaHCO3-EHP > H2O-EHP. UV irradiation was found to improve OP bioavailability, as demonstrated by increased levels of UV-sensitive P (UV-P) and EHP in the extracts after irradiation. The total contents of bioavailable Po in extracts were 5.6–35.3% higher after UV irradiation than before irradiation. Thus, the effect of UV irradiation on the OP bioavailability and release activity cannot be neglected in TGR WLFZ soil. [Display omitted] •Enzymatically hydrolysable organic phosphorus in the water level fluctuation zone soil was dominated by labile monoester P.•Ultraviolet irradiation could improve the bioavailability of organic phosphorus in the water level fluctuation zone soil.•The increase of phytate-like P in NaOH extracts was significantly after ultraviolet irradiation (P