LEAD Action News
LEAD Action News Volume 13 Number 4, June 2013, ISSN 1324-6011
Incorporating Lead Aware Times ( ISSN 1440-4966) and Lead Advisory Service News (ISSN 1440-0561)
The Journal of The LEAD (Lead Education and Abatement Design) Group Inc.
Editorial Team: Elizabeth O’Brien, Zac Gethin-Damon, Hitesh Lohani, Shristi Lohani and David Ratcliffe

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Environmental Risks Arising from Changes in Ammunition Materials

Copyright © 2013 – Cylenchar Limited Dr Peter J Hurley – Cylenchar Limited UK

Site Risk! - Added Pathways

A transport metal is a metal that forms insoluble compounds which have an ability to sorbe heavy metal compounds and can easily be transported by water. Iron oxides are just such materials. Iron has a density of 7.87g/cc. However, iron and its alloys corrode to produce colloidal hydrated iron oxides. Hydrated iron (III) oxide – Limonite, FeO(OH)·nH2O has a density of 2.7 – 4.3 g/cc. In comparison, clays have a density on slightly lighter at 2.16-2.8g/cc . Limonite being colloidal in nature, given sufficient run-off or even a significant breeze, can easily leave a contaminated site. Colloidal iron oxides remain insoluble only where soluble iron in solution around them are in excess. Once transported beyond the zone of iron saturation they simply dissolve to become soluble hydrated iron. Naturally, any toxic cargo of heavy metals they have picked up en-route will also be dumped into solution. Transportation of heavy metals in this manner is termed ‘facilitated transport’.

It is generally believed that facilitated transport of heavy metals by iron oxides, represents the greatest single cause of heavy metals migration. However, iron alumina-silicates and biomass can also perform the same role, sorbing heavy metals on a contaminated site, being carried away in surface run-off only to de-sorbe the soluble pollutants where they reach zone of un saturation.

With loss of surface cover in the form of vegetation and thatch, the elements that bind surface soils are lost. Thus, surface biomass and topsoil can be lost to erosion. These same eroded materials, owing to their proximity to the origin of contamination, are amongst the most contaminated materials on the site. If they are washed or blown away, they will carry contamination with them – And once in a region of low saturation they can dump any sorbed toxic heavy metals. Thus, migrating topsoil and biomass can facilitate the transport of heavy metal contaminants.

Drainage from a contaminated site can leave by one of 2 routes; as surface runoff or subsoil drainage. Where the ability of the soil to drain rainfall is impaired, naturally run-off will increase. Where drainage is through the site soils, there is at least the potential for soluble pollutants washed into the soil, to be sorbed and bound in the soil as moisture percolates through, thereby the potential pollutants can remain close to their source of origin.

Contaminants travelling in surface run-off have less potential of being sorbed and retained on-site. So, naturally an increase in surface run-off will increase the migration of soluble heavy metals from the site.


Environmental Risks Arising from Changes in Ammunition Materials
The Contaminant – Metallic Lead?
Does Steel Shot Reduce Environmental Risk?
European Soils – Typical Profile and Predicted Impact of Steel Shot
Site Risk! - Added Pathways
Mitigation of Site Risk

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