Environmental Mineralogy: Microbial Interactions, Anthropogenic Influences, Contaminated Land and Waste Management
The past 10 years or so have seen the emergence of a discipline known as ‘Environmental Mineralogy’. This should be regarded not as a new discipline per se, but as a new application of traditional mineralogy. Mineralogists have always sought to understand the chemical and physical environment under which a particular mineral forms and to determine the arrangement of atoms within that mineral. The field of Environmental Mineralogy asks the same questions in a different context. For example, can minerals assist in the remediation of contaminated soils and waters? Which minerals can potentially be deleterious to, inter alia, buildings, ecology and human health? Which minerals are suitable as containment for waste? How does the biota interact with minerals? Environmental Mineralogy is emerging as a field that seeks to define the roles of minerals in all environmental systems, and to work towards the preservation and restoration of such systems. Environmental Mineralogy is achieving prominence because of increasing concern regarding the environments in which we live. Mineralogists have perceived a gap in our understanding of how minerals behave in the surface environment and a need for innovative,‘green’ solutions to the problems of contamination and waste. However, the emergence of Environmental Mineralogy also owes much to modern analytical technology. Many minerals in the surface environment fall within the clay-grade range and therefore, demand high-resolution systems for analysis. Similarly, trace elements are now detectable at exceptionally low concentrations in a wide variety of matrices. Further, many mineral-environment interactions need to be examined at the atomic scale for a greater understanding of the interactive processes involved. This requires the application of the latest technologies such as X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and atomic force microscopy to name but a few. The aim of this monograph is to provide an up-to-date account of the state of this diverse subject area. With chapters containing a strong review element, it is hoped that this volume will appeal to both researchers and students alike. The volume is arranged in four sections: (1) mineral-microbe interactions; (2) anthropogenic influences on mineral interactions; (3) minerals in contaminated environments; and (4) minerals and waste management. These four sections by no means give exhaustive coverage of the subject area, but communicate some of the most important developments taking place at the present time.
Heavy metal-bearing Mn oxides in river channel and floodplain sediments
Published:January 01, 2000
K. A. Hudson-Edwards, 2000. "Heavy metal-bearing Mn oxides in river channel and floodplain sediments", Environmental Mineralogy: Microbial Interactions, Anthropogenic Influences, Contaminated Land and Waste Management, J. D. Cotter-Howells, L. S. Campbell, E. Valsami-Jones, M. Batchelder
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Mn oxides are one of the most significant groups of substances which control the distribution of heavy metals in river sediments. This occurs because of their favourable structures, sizes and surface areas. In the Tyne, Tees and Yorkshire Ouse river basins in northeast England, heavy metal-bearing, X-ray amorphous Mn oxides are common (forming upto 15 modal % of heavy metal-bearing grains) though not always abundant phases in river channel and floodplain sediment. Manganese oxides, however, contain significantly more Pb (upto 23 wt.%) than do Fe oxides, and also contain Zn, Cd and Cu (up to 19 wt.%, 0.5 wt.% and 0.8 wt.%, respectively). Within floodplain alluvium, Mn oxides play a major role in controlling the post-depositional redistribution of heavy metals. This is shown by authigenic, Pb-, Zn-, Cd- and Cu-bearing Mn oxides in alluvial profiles at Blagill and Prudhoe in the Tyne basin, and overbank alluvial sediments at Myton-on-Swale and York in the Yorkshire Ouse basin containing multiple horizons of X-ray amorphous Mn-Ba oxides, some of which contain up to 1.0 wt.% Zn. The overbank alluvial sediments at Myton-on-Swale contain the Ba (-Mn) silicate verplanckite [Ba2(Mn,Fe,Ti)Si2O6(OH)2.3H2O], although this contains negligible (<0.1 wt.%) amounts of Zn, Pb, Cr, Ni and Co. Manganese oxides play an environmentally significant role in sequestering heavy metals, as shown by contents of upto 39—74% of total sediment-borne Pb, and 10—35% of total Zn, held by Mn oxides in north-east England fluvial sediments. Lower proportions of readily removable Pb and Zn (0.8 — 18% of total Pb, and 3—26% of total Zn) under ambient conditions suggest that the Mn oxides may be long-term sinks for heavy metals in the fluvial environment.