Contrasting nickel mobilization pathways driven by manganese redox cycling and dissolved organic matter complexation in algal- and macrophyte-dominated lake sediments.

Authors

Xinyue Ren, Chao Deng, Sunling Zhuang, Yueqi Qian, Zhenlan Tang, Musong Chen

Published in

Journal of hazardous materials. Volume 514. Pages 142715. Jun 15, 2026. Epub Jun 15, 2026.

Abstract

Nickel (Ni) remobilization in eutrophic lake sediments is controlled by interactions between iron-manganese (Fe-Mn) redox processes and dissolved organic matter (DOM), but the mechanisms under different ecological regimes remain unclear. Here, we employed an in situ high-resolution approach integrating HR-Peeper sampling and multi-analytical techniques to simultaneously characterize Ni, Fe, Mn, and DOM in sediment pore water, and applied it to algal- (MLW) and macrophyte-dominated (DTH) zones of Taihu Lake over one year. Dissolved Ni concentrations in overlying water exhibited a sharp, synchronous peak during March-April 2021, exceeding the WHO drinking-water limit (70 μg L^-1) by up to 1.4 times. In MLW, this Ni pulse was associated with humic-like DOM-mediated Mn(IV) reduction, evidenced by concurrent increases in Ni, Mn, and humic-like DOM, with Mn identified as the dominant predictor in random forest analysis. Partial least squares path modeling (PLS-PM) further indicated that DOM acted as an electron shuttle, accelerating Mn-oxide reduction (λ = 0.971, p < 0.001) and releasing adsorbed Ni. In contrast, Ni mobilization at the DTH site was primarily governed by DOM complexation. Visual MINTEQ simulations showed that more than 55% of dissolved Ni occurred as Ni-DOM complexes. Consistently, fluorescence titration demonstrated strong coordination between Ni and both protein-like and humic-like DOM components (log K_m > 3.682; r > 0.939). Fourier transform infrared spectroscopy combined with two-dimensional correlation analysis further confirmed that Ni primarily interacted with aromatic C-H, alkene CC, aliphatic -COOH, alcoholic C-O, and aliphatic C-H functional groups. These findings provide new mechanistic insight into redox-DOM coupling and its control on Ni cycling in algal- and macrophyte-dominated sediments.

PMID:
42320096
Bibliographic data and abstract were imported from PubMed on 20 Jun 2026.

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