Sampling pore water at a centimeter resolution in sandy permeable sediments of lakes, streams, and coastal zones

Abstract

Concentration gradients in the solid fraction and pore water of modern sediments allow to identify benthic biogeochemical processes and the associated fluxes. Gradients are often obtained from layers sampled below the sediment–water interface from sediment cores. Numerous examples in the literature show results from cores collected in impermeable porous sediments, but very few from permeable sediment cores. Indeed, the acquisition of vertical profiles in sandy permeable sediments with a spatiotemporal resolution equivalent to that of muddy sediments is a challenge. We present here a simple protocol that allows sampling of sandy sediments and their interstitial waters with a vertical resolution of 1 cm. This method is suitable for shallow environments, such as intertidal zones, lakes, lagoons, and stream beds. The method is based on rapid conditioning of hand‐collected cores. The cores are pre‐cut lengthwise. Immediately after recovery, they are laid horizontally, opened, and sliced. Interstitial water is collected by centrifugation on site shortly after cutting the core with tubes equipped with a 0.2 μm membrane. Optimally, 30 min is sufficient between core collection and conditioning of 12 sections of a 20‐cm long core. The examples shown indicate that the method is reproducible. Reduced dissolved compounds such as Fe(II), Mn(II), and NH4+ show profiles without significant oxidation. At the time of core cutting, small volumes of pore water are seeping out of the core, but for sediments with a permeability of up to 10−10 m2, this seepage does not disturb the shape of the pore‐water profiles.

Advances and development in sampling techniques for marine water resources: a comprehensive review

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The Ellrott grab: A small, lightweight sediment sampler for collecting undisturbed sandy sediments

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Perfluoroalkyl substances in the environment and biota from the coasts of the South China Sea: profiles, sources, and potential risks

“…The detection of PFAS in water and biota provides effective information on the current use of PFAS (Anschutz and Charbonnier, 2020;Sebastiano et al, 2021), especially after the implementation of restrictive policies in various countries. Sediments have the capacity for adsorption and desorption of PFAS, so they are recognized as significant reservoirs for these compounds (Eschauzier et al, 2010).…”