Omar Félix. IAGS, April,20,2015. Tucson, AZ

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1 Omar Félix IAGS, April,20,2015 Tucson, AZ

2 Mining Operations Important economic activity Arizona is one of the most important copper producers Minerals/metals are used in all kinds of industries Adverse effects on the environment 2 of 27

3 Why do we care about mining operation particles? Chemical Composition Metal and metalloid contaminants (some toxic). Particle Size <2 μm deposits in the lungs >7 μm deposits in the upper respiratory tract Least efficient deposition from μm Maynard, of 27

4 Lead Pollution caused by anthropogenic Pb has many sources. Mining operations. Anthropogenic sources >> Natural sources. Atmosphere is the major initial recipient. The phasing out of leaded gasoline increased the relative contribution of other sources of industrial lead in atmospheric pollution. Source: US EPA, 2002 (Sources of airborne lead emissions in the USA) 4 of 27

5 Source Contribution It is important to know the source of pollution to prevent further environmental issues. Knowing the total Pb concentration is not sufficient for a precise evaluation of contaminant sources. Lead isotopes have been introduced as fingerprints of environmental pollution. Each source of Pb can have distinct isotopic ratio ranges. 5 of 27

6 Principles of lead isotopic fingerprinting Different types of ore deposits and anthropogenic sources of lead have distinct isotope ratios. Isotopic composition of Pb is commonly expressed as ratios 207 Pb/ 206 Pb, 208 Pb/ 206 Pb. They can be measured accurately. The abundances of these isotopes are relatively important. 6 of 27

7 Application of lead isotopic fingerprinting Change of lead isotopic ratios in atmospheric aerosols: Leaded gasoline 7 of 27 a. Chen et al., 2005 b. Grousset et al., 1994

8 Field Sites Iron King Inactive copper mine now a Superfund site with arsenic and lead contaminated mine tailings Hayden & Winkelman Active copper mine with smelter, arsenic and lead contaminated mine tailings Tucson To determine the isotopic ratios in common urban environment 8 of 27

9 Equipment and Methods MOUDI (Micro-Orifice Uniform Deposit Impactor) 10 aerosol size fractions on separate stages. Cut-point diameters of 18, 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32, 0.18 µm, 0.1 and µm. 30 L/min flow rate. Weather Station Wind speed/direction, temperature, relative humidity. MOUDI programmed according to wind direction Acid extraction Aqua regia: 2.23M HCl and 1.03M HNO 3 Sonicate at 80 C for 1 hour. Total lead and isotopic analyses performed by ICP-MS. 9 of 27

10 Hayden-Winkelman Proposed to be listed on the National Priority List (NPL) Contaminated Media Surface water Ground water Air Soil Facilities: Source: azbex.com 10 of 27 ocrushing and grinding oconcentrator osmelter otailings damns

11 Objectives To determine the isotopic lead composition of fine and coarse particles in atmospheric dust and aerosols to assess potential sources of contamination. To measure lead isotope ratios in atmospheric dust from various field sites. This will help establish variability in samples from different sources. 11 of 27

12 Annual averaged metal and metalloid content in atmospheric dust at Hayden, Az Average As and Cd Concentration (ng m -3 ) 3.0 Pb Cd 2.5 As Average Pb Concentration (ng m -3 ) 0.0 AF of 27 Cutpoint Diameter (µm) Coarse Fraction: 3.2 µm to 5.6 µm Fine Fraction: 0.3 µm to 0.56 µm

13 Hayden Isotopic Results: All Wind Directions 208/ Period 1 Coarse Period 1 Fine Period 2 Coarse Period 2 Fine Growth curve /206 b. c. 13 of 27

14 Hayden Isotopic Results: Wind Direction From Smelter / Period 3 Coarse Period 3 Fine Period 4 Coarse Period 4 Fine Period 5 Coarse Period 5 Fine Ray Mine Ore Growth curve /206 b. 14 of 27

15 15 of 27 SEM

16 Comparison Between Hayden and Tucson / Tucson Coarse and Fine Hayden Coarse Hayden Fine / of 27 Coarse Fraction: 3.2 µm to 5.6 µm Fine Fraction: 0.3 µm to 0.56 µm

17 Soil Sampling at Hayden-Winkelman 300 Smokestack Concentration (ppm) As Pb of m Distance from the Smelter (m)

18 Soil Sampling at Hayden-Winkelman / Hay A (0-3) Hay A (100) Hay B (0-3) Hay B (100) Hay C (0-3) Hay C (100) / of 27

19 Iron King Superfund Site Late 1800 s to early 1960 s. 182 acres Tailings, slag and grey smelter ash acres 19 of 27 Tailings, waste rock piles and retention ponds

20 Iron King Superfund Site IK Mine Site As (ppm) Pb (ppm) Highest Average Lowest As (ppm) Pb (ppm) Highest Average Lowest Smelter Site 20 of 27 Arizona Residential SRL: As = 10 ppm; Pb = 400 ppm

21 Iron King Superfund Site Courtesy of Mackenzie Russell 21 of 27

22 Objectives To determine the isotopic lead composition of soil samples to assess potential sources of contamination. To determine the total concentration of some elements that can be used as tracers to assess the extension of the contamination. 22 of 27

23 23 of 27 Sampling Points: IK Superfund Site

24 Lead and Arsenic Concentrations: IK Superfund Site ppm Pb 100 As Distance (m) 24 of 27

25 Lead Isotopes: IK Superfund Site m m Tailings m 208/ m m / of 27

26 Conclusions Lead Isotopic analyses are a good tool for tracing sources of atmospheric pollution. Determination of trace elements is important to assess the extension and magnitude of the contamination. Concentration of contaminants is closely related to size particle 26 of 27

27 Acknowledgments Dust Group Superfund Research Program 27 of 27