High mobilization of phosphorus in black-odor river sediments with the increase of temperature

Increased temperatures affect water quality and ecology. However, the response of geochemical cycles of phosphorus (P) in black-odor river sediments to increased temperatures is still unclear. In this study, we found that porewater soluble reactive phosphorus (SRP) concentrations in sediments significantly increasedwith the rising of temperature, by 28% and 87% at 25 degrees C and 35 degrees C, respectively, comparedwith concentration at 15 degrees C (p< 0.01, independent samples t-test). The significant decrease of iron (Fe) binding P in sedimentswas observed (p< 0.01) because of dissolved oxygen (DO) and redox potential (Eh) decreasingwith the rising of temperature from15 degrees C to 35 degrees C. This demonstrated that the reduction of Fe (III) oxyhydroxideswas one of the major reasons for the release of SRP in sediments. Furthermore, themobility of P increasing through competing absorption of minerals by dissolved organic matter (DOM) was another reason for the release of SRP in sediments. This was supported by the significant decrease of immobile-P, and increase of mobile-P in sediments. Additionally, the simultaneous increase of SRP and DOM, and a significant positive correlation between themwere observed in sedimentswith increasing temperatures (r = 0.776, p < 0.001). (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Increased temperatures lead to higher concentrations of soluble reactive phosphorus in black-odor river sediments, with a decrease in iron binding phosphorus and an increase in phosphorus mobility through competing absorption of minerals by dissolved organic matter. This demonstrates that the reduction of Fe (III) oxyhydroxides and competition for absorption are major reasons for phosphorus release in sediments.