Understanding the impact of chemical composition and environmental factors on phosphorus species distribution in rivers: A large-scale study in Taihu Lake Basin

To effectively remove phosphorus from rivers, there has been increasing attention on the various phosphorus species present. However, the factors influencing the distribution of these species have not been systematically investigated. This study examines the effects of chemical composition and environmental factors on phosphorus species distribution by analyzing river samples and conducting simulation experiments. Results indicated that phosphorus predominantly exists in particulate (33.24 −206.58 μg/L) and colloidal phases (7.91 −62.95 μg/L). Notable correlations were observed between metallic elements and inorganic phosphorus (IP) (R = 0.67 −0.88), as well as between organic carbon (OC) and organic phosphorus (OP) (R = 0.76 −0.82). Further analyses revealed that metal elements are electrostatically bound to IP, while OP is primarily produced alongside OC during organic matter decomposition. The study also highlights the influence of anions in water, which facilitate phosphorus release from particulate and colloidal forms. The examination of environmental factors revealed that both warming and anaerobic conditions led to an increase in various phosphorus species. However, the increase in particulate was less pronounced compared to the colloidal and dissolved phases. Notably, under aerobic conditions, phosphorus from the colloidal and dissolved phases is converted into particulate. These findings enhance our understanding of the distribution of phosphorus species and provide valuable insights for the eutrophication management. • The inorganic and organic phosphorus are influenced by the inorganic elements and organic carbon, respectively. • The presence of anions facilitates the release of phosphorus from particulates and colloids. • Under warming or anaerobic conditions, the increase varied among different phosphorus species. • Under aerobic conditions, colloidal and dissolved phosphorus is retained in the particulate phase.