Is there a significant diffusive salt-pump mechanism for the transport of organic contaminants from the marine environment into fresh water aquifers? A discussion contribution

• Published in: Environmental earth sciences 2005-12, Vol.49 (2), p.207-213
• Main Authors: BRIDGE, M. E, LLOYD, D. R
• Format: Article
• Language: English
• Subjects: Aquifers; Coastal aquifers; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental impact; Exact sciences and technology; Freshwater; Geochemistry; Hydrogeology; Hydrology. Hydrogeology; Marine; Marine environment; Marine pollution; Mineralogy; Organic contaminants; Pollution, environment geology; Saline water; Salinity; Sediment transport; Silicates; Water geochemistry; Water pollution
• ISSN: 0943-0105; 1866-6280; 1432-0495; 1866-6299
• DOI: 10.1007/s00254-005-0048-5

We analyse recent claims of an additional risk of diffusive intrusion by marine organic contamination (OC) into coastal aquifers, and discuss the activity-driven "salt-pump mechanism" which is claimed to accelerate this diffusion. The reported accelerations of transport of OC out of saltwater are far too large to be due to activity effects on simple diffusion. There probably is a small acceleration of diffusion out of saltwater, but there is no direct experimental evidence for this. Possible experimental artefacts are suggested. Larger effects on diffusion in the literature are shown to be not relevant to this problem. Diffusion of suspended OC, present in the experiments, is too slow to be significant; however, this suspended material is shown to have serious implications for the proposed interpretation of the results. Until these results are better understood, no conclusions about any possible environmental implications can be drawn from them.[PUBLICATION ABSTRACT]