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Can earthworm-secreted calcium carbonate immobilise Zn in contaminated soils?
DOI:
10.1016/j.soilbio.2014.01.012
Authors:
Loredana
Brinza
(Diamond Light Source)
,
Paul
Schofield
(Natural History Museum)
,
Fred
Mosselmans
(Diamond Light Source)
,
Erica
Donner
(University of South Australia)
,
Enzo
Lombi
(University of South Australia)
,
David
Paterson
(Australian Synchrotron Clayton)
,
Mark
Hodson
(University of York)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Soil Biology And Biochemistry
State:
Published (Approved)
Published:
January 2014
Diamond Proposal Number(s):
7755
,
7090
,
5731
,
2123
Abstract: We investigated the interaction of soil Zn with calcium carbonate granules secreted by the earthworm Lumbricus terrestris. Earthworms were kept in agricultural soil amended with ZnSO4 to give Zn concentrations up to 750 mg kg?1 and in two former mine site soils containing 500 and 120 mg Zn kg?1. After 21–42 days the earthworms accumulated 260–470 mg Zn kg?1. Granule production was 0.027–2.11 mg CaCO3 earthworm?1 day?1 and was positively correlated with soil and soil solution pH (r = 0.66 and 0.85 respectively, p ? 0.01). Granule Zn concentration was 34–163 mg kg?1. Granules collected from Zn-free control soil and left in Zn-bearing soil for 28 days contained 49–60 mg Zn kg?1 suggesting that the majority of Zn associates with granules after their secretion. However, synchrotron X-ray fluorescence indicates some incorporation of Zn into granules during their formation. X-ray diffraction and X-ray absorption spectroscopy indicate that the granules are predominantly calcite and the spectroscopy suggests that the Zn is either adsorbed to, or incorporated into, the calcite lattice. X-ray diffraction of the outer c. 35 ?m of the granules supports incorporation of Zn into the calcite lattice. The low granule production rates in the mine site soils and the granule Zn concentrations suggest that earthworm secreted calcium carbonate is unlikely to impact significantly on Zn mobility in soils.
Journal Keywords: Lumbricus terrestris; Calcite; Metal; Adsorption; Coprecipitation; XAS; Synchrotron
Diamond Keywords: Bioremediation
Subject Areas:
Environment,
Biology and Bio-materials,
Chemistry
Instruments:
I18-Microfocus Spectroscopy
Other Facilities: XFM at Australian Synchrotron
Added On:
19/02/2014 14:25
Discipline Tags:
Desertification & Pollution
Earth Sciences & Environment
Biochemistry
Chemistry
Life Sciences & Biotech
Technical Tags:
Imaging
Spectroscopy
X-ray Fluorescence (XRF)
X-ray Absorption Spectroscopy (XAS)
Microfocus XAS