Soil Biology and Biochemistry, July, 2014, Vol.74, p.1(10)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2014.01.012 Byline: L. Brinza, Paul F. Schofield, J. Fred W. Mosselmans, Erica Donner, Enzo Lombi, David Paterson, Mark E. Hodson 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 ZnSO.sub.4 to give Zn concentrations up to 750 mg kg.sup.-1 and in two former mine site soils containing 500 and 120 mg Zn kg.sup.-1. After 21-42 days the earthworms accumulated 260-470 mg Zn kg.sup.-1. Granule production was 0.027-2.11 mg CaCO.sub.3 earthworm.sup.-1 day.sup.-1 and was positively correlated with soil and soil solution pH (r = 0.66 and 0.85 respectively, p [less than or equal to] 0.01). Granule Zn concentration was 34-163 mg kg.sup.-1. Granules collected from Zn-free control soil and left in Zn-bearing soil for 28 days contained 49-60 mg Zn kg.sup.-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 [mu]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. Author Affiliation: (a) Diamond Light Source Ltd., Harwell Science and Innovation Campus, Chilton, Didcot OX11 0DE, UK (b) Mineral and Planetary Sciences, Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK (c) Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia (d) X-ray Microanalysis Beamline, Australian Synchrotron Clayton, Victoria 3168, Australia (e) Environment Department, University of York, Heslington, York YO10 5DD, UK Article History: Received 23 October 2013; Revised 28 December 2013; Accepted 12 January 2014
Calcite Crystals ; X-Ray Spectroscopy ; Fluorescence ; Zinc Compounds ; Calcium Carbonate ; Soils
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