Significance of riverine suspended particulate matter input on photoreduction and accumulation of mercury in coastal areas: Insights from sediment mercury isotopes.
Article
Liu, Xiaoquan, Wang, Yingjun, Ji, Xiaomeng et al. (2025). Significance of riverine suspended particulate matter input on photoreduction and accumulation of mercury in coastal areas: Insights from sediment mercury isotopes.
. JOURNAL OF HAZARDOUS MATERIALS, 501 140699. 10.1016/j.jhazmat.2025.140699
Liu, Xiaoquan, Wang, Yingjun, Ji, Xiaomeng et al. (2025). Significance of riverine suspended particulate matter input on photoreduction and accumulation of mercury in coastal areas: Insights from sediment mercury isotopes.
. JOURNAL OF HAZARDOUS MATERIALS, 501 140699. 10.1016/j.jhazmat.2025.140699
Riverine suspended particulate matter (SPM) exerts a fundamental yet poorly quantified influence on coastal mercury (Hg) cycling. In particular, its effects on the photochemical reduction and sedimentary accumulation of Hg remain elusive. Here, we integrate measurements of seawater SPM concentrations, sediment Hg contents, and isotopic compositions in the highly turbid Yellow River Estuary (YRE) with global coastal datasets to elucidate the role of SPM in modulating Hg transport and transformations. We demonstrated that Hg(II) photoreduction in the YRE is markedly suppressed (<5 %), as indicated by relatively low Δ¹ ⁹⁹Hg values-contrasting with the widespread occurrence of more significant photoreduction in clearer coastal waters (∼10 %). Isotopic source apportionment further revealed that Yellow River-derived SPM contributed 51.8 ± 18.5 % of total Hg inputs to the estuary and driven about 73 % of all Hg burial in surface sediments. A synthesis of global data revealed a consistent negative relationship between SPM concentrations and Δ¹ ⁹⁹Hg, indicating that elevated SPM attenuated light penetration and inhibited Hg photoreduction. Moreover, high SPM loads accelerated Hg sequestration, with each 10 mg/L increase in SPM enhancing sedimentation rate by 0.18 ± 0.04 cm/yr. Collectively, these findings provided the quantitative evidence linking SPM levels to the suppression of coastal Hg photoreduction and enhanced sediments Hg accumulation, offering new insights into the particulate controls on global coastal Hg cycling.
