Coupling mechanisms of S–Fe–P in surface sediments under the stresses of high salinity and heavy metals in coastal rivers

The aim of the study was to (1) investigate distributions sulfur (S), iron (Fe), and phosphorus (P) in coastal surface sediments under stresses high salinity heavy metals; (2) identify potential sources environmental geochemical process S–Fe mineral accumulation; (3) elucidate coupling mechanisms S–Fe–P stresses. reduced inorganic (RIS), P, reactive Fe (RFe) two rivers with metals (~50 psu, brine drainage) offshore areas Bohai Sea were investigated. Pyrite (CRS) predominant fraction RIS (Jiaolai River (JL), 56%; Jiehe (JH), 72%), whereas acid volatile (AVS) dominated their (L, 66%; J, 45%). RFe(II) RFe JH (70%) JL (66%), while RFe(III) fractions (53%). Coastal by HCl-P (Ca-bound P) NaOH-P (Fe- Al-bound P), respectively. Accumulated sulfide limited elemental (ES) availability salinity, it total organic carbon (TOC) when river heavily polluted. High produced sulfide-dominated environments, which could reduce facilitate immobilization. However, presence resulted Fe-dominated promote metal sulfides formation increase fixation.