New paper explores heterogeneity of porewater chemistry in clay-rich sediments

In a paper published in the journal Chemical Geology, Wenkai Qiu and co-authors present new geochemical data on porewaters extracted from unconsolidated argillaceous sediments collected in the Jianghan Plain, central China. The extraction experiments were carried out by increasing the loading stress on the sediments, either continuously or in a segmented manner. The results illustrate the large and complex variations in total concentration, chemical speciation, and isotopic composition of various solutes including ammonium, arsenic, DOC, strontium, and alkalinity. These variations are attributed to the limited exchanges between free and bound porewater, non-uniformity of water-rock interactions, and mixing effects related to differences in the moveable porewater fraction generated under the different imposed loading stress regimes. The major conclusion is that the binding strength of porewater carries both hydrological and geochemical significance by bridging pore-scale hydrodynamics and solute mobilization in unconsolidated argillaceous sediments. The paper’s first author is Wenkai Qiu wrote the first draft of the manuscript while a visiting PhD student in the Ecohydrology Research Group. Co-authors include colleagues from China University of Geosciences and Philippe Van Cappellen.

Link to paper: https://www.sciencedirect.com/science/article/pii/S0009254125002037

Qiu W., Ma T., Du Y., Zheng B., Peng Z., Shang R. Xiao C., Luo K., Van Cappellen P. (2025) Inhomogeneous porewater geochemistry in unconsolidated argillaceous sediments: Implications for porewater extraction protocols and characterization of solute mobilization. Chemical Geology 685, 122813.