Temperature-induced diurnal redox potential in soil - Kölner UniversitätsPublikationsServer

Dorau, Kristof, Bohn, Bianca, Weihermueller, Lutz and Mansfeldt, Tim (2021). Temperature-induced diurnal redox potential in soil. Environ. Sci.-Process Impacts, 23 (11). S. 1782 - 1791. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 2050-7895

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DOI:10.1039/d1em00254f

Abstract

With the capabilities to measure redox potentials (E-H) at a high temporal resolution, scientists have observed diurnal E-H that occur in a distinct periodicity in soils and sediments. These patterns have been disregarded for a long time because minor fluctuations of the E-H in the tens of mV range are difficult to interpret. Various explanations have been proposed for the origin of diel E-H but a cohesive assessment of the temperature-dependency for field- and laboratory-based investigations is missing at present. In this study, we investigated spatiotemporal diel E-H of previous long-term (up to 10 years) field- and lab-based monitoring data collected at high-temporal (every hour) and spatial (up to 6 depths) resolution. In addition, we set up a redox experiment where we manipulated the soil temperature (ST) by diel temperature cycles to assess the E-H response. Diel fluctuations were absent for laboratory experiments with Delta E-H of a few mV (daily EH-max - daily EH-min), but we found pronounced fluctuations up to similar to 100 mV for field investigations. The spatiotemporal pattern in E-H fluctuations was amplified in the topsoil during the summer months concomitant with ST. We showed for the first time that changes in ST during an incubation experiment altered the E-H by -3.3 mV degrees C-1 and inferred that the diel E-H were driven by the thermal conditions of the soil itself. This is particularly important when E-H is measured close to the soil surface and underlines that minor fluctuations of the E-H with a recurring periodicity should be carefully checked for its dependency with the soil and reference electrode temperature. Redox measurements should not be considered a routine determination and cautious handling of E-H data by physical sound corrections is urgently needed in order to link Delta E-H to daily biogeochemical cycling in soils.

Item Type:

Journal Article

Creators:

Creators	Email	ORCID	ORCID Put Code
Dorau, Kristof	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Bohn, Bianca	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Weihermueller, Lutz	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Mansfeldt, Tim	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED