Soil acidification enhances the mobilization of phosphorus under anoxic conditions in an agricultural soil: Investigating the potential for loss of phosphorus to water and the associated environmental risk

Zhang, ShuaiShuaiZhangYang, XingXingYangHsu, Liang-ChingLiang-ChingHsuLiu, Yu-TingYu-TingLiuSHAN-LI WANGWhite, John R.John R.WhiteShaheen, Sabry M.Sabry M.ShaheenChen, QingQingChenRinklebe, JörgJörgRinklebe2022-04-252022-04-252021-11-0100489697https://www.scopus.com/pages/publications/85108420065?inwardhttps://scholars.lib.ntu.edu.tw/handle/123456789/606035Soil redox potential (EH) and pH are key parameters regulating the solubility and fate of phosphorus (P). However, the impact of soil acidification on the redox-induced mobilization and speciation of P in soils under a wide range of EH values has not been extensively studied. Here, we investigated the mobilization and speciation of P in an acidified agricultural soil at two different pH values (e.g., highly acidic soil; pH = 5.6 and slightly acidic soil; pH = 6.1) compared to the un-acidified soil (control soil; pH = 7.3) under a wide range of EH condition (+459 to −281 mV). The impacts of EH/pH-dependent changes of Fe-Mn oxides, and dissolved organic (DOC) and inorganic (DIC) carbon on P mobilization and speciation were also investigated using geochemical and spectroscopic (X-ray absorption near edge structure) techniques. The concentrations of dissolved P under anoxic conditions increased up to 69.3% in the highly acidic soil compared with the control soil. The decrease of the Fe-P fraction, the decrease of Ferrihydrite-Pads speciation, and the strong linear correlation between the dissolved P and Fe2+ (R2 > 0.85) supports the finding that enhanced P mobilization under anoxic conditions may be attributed to Fe reduction in the highly acidic soil. The concentration of dissolved Fe and P remained low until pH dropped below 6.35 for P and 6.28 for Fe, while a liner increase was found in dissolved Mn accompanying a general trend of pH decrease. This result suggests that the dissolution of reducible Mn under acidic soil conditions was an important factor for enhancing mobilization of dissolved P under anoxic conditions. This trend was due to the low amount of Mn, indirectly speeding up Fe reduction. These results can help to develop management practices to effectively mitigate P export and protect water resources from diffuse P pollution.Diffuse P pollution lossEutrophicationFe-Mn reductionRedox dynamic changesSoil acidification[SDGs]SDG2[SDGs]SDG6Soil acidification enhances the mobilization of phosphorus under anoxic conditions in an agricultural soil: Investigating the potential for loss of phosphorus to water and the associated environmental riskjournal article10.1016/j.scitotenv.2021.148531341755972-s2.0-85108420065