Selective sorption and desorption of DOM in Podzol horizons - DOC and aluminium contents of leachates from a column experiment

Sara Ramos Dos Santos; Judith Schellekens; Peter Buurman; Jean-Thomas Cornelis; Karen Vancampenhout; Wilson Tadeu Lopes da Silva; Plínio Barbosa de Camargo; Pablo Vidal-Torrado

doi:10.1016/j.scitotenv.2023.162234

Selective sorption and desorption of DOM in Podzol horizons - DOC and aluminium contents of leachates from a column experiment

Sci Total Environ. 2023 May 10:872:162234. doi: 10.1016/j.scitotenv.2023.162234. Epub 2023 Feb 13.

Authors

Sara Ramos Dos Santos¹, Judith Schellekens², Peter Buurman³, Jean-Thomas Cornelis⁴, Karen Vancampenhout⁵, Wilson Tadeu Lopes da Silva⁶, Plínio Barbosa de Camargo⁷, Pablo Vidal-Torrado¹

Affiliations

¹ Soil Science Department, Luiz de Queiroz Agricultural College - University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, Piracicaba, SP, Brazil.
² Soil Science Department, Luiz de Queiroz Agricultural College - University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, Piracicaba, SP, Brazil; Department of Earth and Environmental Sciences, KU Leuven, Celestijnenlaan 200E, Leuven, Belgium. Electronic address: schellekens.j@hetnet.nl.
³ Water Systems and Global Change group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands.
⁴ Faculty of Land and Food Systems, University of British Columbia, V6T 1Z4 Vancouver, BC, Canada.
⁵ Department of Earth and Environmental Sciences, KU Leuven, Celestijnenlaan 200E, Leuven, Belgium.
⁶ Brazilian Agricultural Research Corporation - EMBRAPA Instrumentation Center, R. 15 de Novembro, 1452, São Carlos, SP, Brazil.
⁷ Center of Isotopic Energy in Agriculture, University of São Paulo, Av. Centenário, 303 - São Dimas, Piracicaba, SP, Brazil.

PMID: 36791854
DOI: 10.1016/j.scitotenv.2023.162234

Abstract

Complexation of dissolved organic matter (DOM) with cations and minerals contributes to the stabilization of carbon in soils, and can enable the transport of metals in the environment. Hence, a proper understanding of mechanisms that control DOM binding properties in the soil is important for major environmental challenges, such as climate change and stream pollution. However, the role of DOM source in those mechanisms remains understudied. Here, we consider poorly drained tropical Podzols as a model environment to isolate effects of aluminium and DOM on sorption and desorption processes in podzolisation. We collected E- and Bh-horizons from a Brazilian coastal Podzol under tropical rainforest to conduct a column experiment, and percolated the columns with DOM collected from a stream (Stream), peat water (Peat), litter (Litter) and charred litter (Char). To quantify sorption and desorption from the columns, leachates were analysed for DOC content, aluminium content, pH, and the amount of fulvic acid relative to humic acid. The results showed large differences in DOC retention between DOM-types, which were consistent over all columns. Retention of DOC in the column varied between 25 % and 92 % for DOM-type Stream, between 33 % and 63 % for DOM-type Peat, between 22 % and 47 % for DOM-type Litter, and between 8 % and 49 % for DOM-type Char. Similarly, desorption from columns with B-horizon material highly differed between DOM-types. Percolation with DOM-types Stream and Peat caused a release of native DOC from B columns that was higher than in those percolated with water only. On the other hand, percolation of B columns with DOM-types Litter and Char caused a net DOC retention. These differences reflect that certain DOM-types hindered desorption, while other DOM-types caused active desorption. The large differences in sorption/desorption between DOM-types implies that changes in environmental conditions may highly influence the fate of soil carbon in Podzols.

Keywords: Adsorption; Complexation; Desorption; Humic substances; Podzol B-horizon; Soil carbon.