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Adsorption and desorption dynamics of citric acid anions in soil

Adsorption and desorption dynamics of citric acid anions in soil
Adsorption and desorption dynamics of citric acid anions in soil
The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes.
1351-0754
733-742
Oburger, E.
972758fd-92c4-4b03-9bdc-91b68dace492
Leitner, D.
314b2855-ce9a-43e2-b9d9-66a4d5a0bf6d
Jones, D.L.
4c7d0ebb-b7e3-4afc-adbc-ece2ba1fc54f
Zygalakis, K.
c5d39b69-54fd-47cf-aaa9-9c907a25f93d
Schnepf, A.
6792762b-b59d-4e2d-8773-54eebfb2fbf7
Roose, Tiina
3581ab5b-71e1-4897-8d88-59f13f3bccfe
Oburger, E.
972758fd-92c4-4b03-9bdc-91b68dace492
Leitner, D.
314b2855-ce9a-43e2-b9d9-66a4d5a0bf6d
Jones, D.L.
4c7d0ebb-b7e3-4afc-adbc-ece2ba1fc54f
Zygalakis, K.
c5d39b69-54fd-47cf-aaa9-9c907a25f93d
Schnepf, A.
6792762b-b59d-4e2d-8773-54eebfb2fbf7
Roose, Tiina
3581ab5b-71e1-4897-8d88-59f13f3bccfe

Oburger, E., Leitner, D., Jones, D.L., Zygalakis, K., Schnepf, A. and Roose, Tiina (2011) Adsorption and desorption dynamics of citric acid anions in soil. European Journal of Soil Science, 62 (5), 733-742. (doi:10.1111/j.1365-2389.2011.01384.x).

Record type: Article

Abstract

The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes.

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e-pub ahead of print date: 26 July 2011
Published date: July 2011
Organisations: Bioengineering Group

Identifiers

Local EPrints ID: 201903
URI: http://eprints.soton.ac.uk/id/eprint/201903
ISSN: 1351-0754
PURE UUID: e112abc7-0138-463a-a047-e54306538edb
ORCID for Tiina Roose: ORCID iD orcid.org/0000-0001-8710-1063

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Date deposited: 02 Nov 2011 14:39
Last modified: 29 Aug 2019 00:40

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Contributors

Author: E. Oburger
Author: D. Leitner
Author: D.L. Jones
Author: K. Zygalakis
Author: A. Schnepf
Author: Tiina Roose ORCID iD

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