2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 107-3
Presentation Time: 9:00 AM-6:30 PM


BROWN, Reid D., Earth and Enviromental Science, New Mexico Institute of Mining and Technology, 801 Leroy Pl., Socorro, NM 87801, reiddbrown@gmail.com

Abandoned mines pose significant risks to environmental and human health. While some work has been done on uranium mine waste contamination of surface water, ground water, and soil, little has been done to investigate the health risks to humans and wildlife from the aeolian transport of contaminated dust particles. In arid environments this is of particular concern due to the frequency of dust storms. At the Jackpile mine in Laguna Pueblo, NM, 15 sets of dust traps have been installed on vertical posts at heights of 0.25 m, 0.5 m, 1.0 m. and 1.5 m above the ground surface. The dust traps were installed at a range of distances from the source, from within the mine pit to approximately 4 km away. Soil samples have been collected at each site and dust samples will be collected every other month as well as collected after individual windstorm events. Soil and dust samples will be sieved into different size classes using 2 mm, 1.5 mm, 1.00 mm, 0.5 mm, 0.25 mm, 0.125 mm, 0.09 mm and 0.063 mm sieves. The samples will then be digested and uranium content will be analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). First, we will analyze our samples for correlation between dust and soil contamination to 1) evaluate if soil contamination can be used as an indicator for the risk of airborne contamination, and 2) gain insight into the possibility that dust is the source of soil contamination. Secondly, we will investigate whether uranium has an affinity for a particular size class of dust. Of special interest are the particles small enough to be completely inhaled by humans.

Preliminary results show that surface concentrations of uranium vary substantially across the landscape. Distance from the pit shows no correlation with concentration of uranium in the upper 5 cm of soil, however, vegetation height does. This correlation suggests that vegetation height and density may influence dust transport across the land surface. Uranium concentrations in the top 5 cm of soil tend to be higher at sites with vegetation height of 1.0 m or greater compared to the majority of sites with 30 cm grass. This work will be a step forward in closing the gap of knowledge in this area of potential human health risk.