Contrasting temperature responses of dissolved organic carbon and phenols leached from soils.

Jonathan S Williams,Jennifer A J Dungait,Roland Bol,Geoffrey D Abbott

doi:10.1007/s11104-015-2678-z

Jonathan S Williams, Jennifer A J Dungait + Show 2 more

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https://doi.org/10.1007/s11104-015-2678-z

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Abstract

Background and aimsPlant-derived phenols are a major input to the terrestrial carbon cycle that might be expected to contribute substantially to dissolved organic carbon (DOC) losses from soils. This study investigated changes in DOC and phenols in leachates from soil treated with individual plant litter types under seasonal temperature change.MethodsSenescing grass, buttercup, ash and oak litters were applied to soil lysimeters. Leachates were collected over 22 months and analysed for DOC and phenols. Phenols in litter and DOC were analysed using on-line thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH).ResultsMass loss differed between litter type (buttercup>ash>grass>oak). Phenol concentrations in the senescing litters (<2 % TOC) were small, resulting in minor losses to water. Seasonal soil temperature positively correlated with DOC loss from litter-free soils. An initial correlation between temperature change and total phenol concentration in grass and ash litter treatment leachates diminished with time. Dissolved phenol variety in all litter-amended soil leachates increased with time.ConclusionsPlant-derived phenols from senescing litter made a minor contribution to DOC loss from soils. The strength of the relationship between seasonal temperature change and phenol type and abundance in DOC changed with time and was influenced by litter type.Electronic supplementary materialThe online version of this article (doi:10.1007/s11104-015-2678-z) contains supplementary material, which is available to authorized users.

Highlights

Losses of dissolved organic carbon (DOC) from soils are amongst the least understood fluxes of the terrestrial carbon cycle
Total organic carbon ranged from 49.1 % in oak litter to 40.5 % in buttercup litter initially, which was reduced to 43.9 % and 33.3 % at 671 days
Plant-derived polyphenolic polymers such as lignin are a major input to the terrestrial C cycle that might be expected to contribute substantially to losses of DOC from soils

Summary

Introduction

Losses of dissolved organic carbon (DOC) from soils are amongst the least understood fluxes of the terrestrial carbon cycle. The transfer of organic carbon from plants to soil to waterways is governed by direct surface flows of particulate organic matter (POM) and sediment-associated organic carbon (Peukert et al 2014), and sub-surface flows of DOC via hydrological pathways through the soil profile (Lloyd et al 2012). The latter pathway is the most difficult to quantify because of the difficulty in meaningfully intercepting flows for measurement, and the general lack of knowledge about the factors that control the rates of turnover and loss of SOC as DOC (see recent review by Kaiser and Kalbitz 2012). Electronic supplementary material The online version of this article (doi:10.1007/s11104-015-2678-z) contains supplementary material, which is available to authorized users

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