A review on the importance of metals and metalloids in atmospheric dust and aerosol from mining operations

Abstract

Contaminants can be transported rapidly and over relatively long distances by atmospheric dust and aerosol relative to other media such as water, soil and biota; yet few studies have explicitly evaluated the environmental implications of this pathway, making it a fundamental but understudied transport mechanism. Although there are numerous natural and anthropogenic activities that can increase dust and aerosol emissions and contaminant levels in the environment, mining operations are notable with respect to the quantity of particulates generated, the global extent of area impacted, and the toxicity of contaminants associated with the emissions. Here we review (i) the environmental fate and transport of metals and metalloids in dust and aerosol from mining operations, (ii) current methodologies used to assess contaminant concentrations and particulate emissions, and (iii) the potential health and environmental risks associated with airborne contaminants from mining operations. The review evaluates future research priorities based on the available literature and suggest that there is a particular need to measure and understand the generation, fate and transport of airborne particulates from mining operations, specifically the finer particle fraction. More generally, our findings suggest that mining operations play an important but underappreciated role in the generation of contaminated atmospheric dust and aerosol and the transport of metal and metalloid contaminants, and highlight the need for further research in this area. The role of mining activities in the fate and transport of environmental contaminants may become increasingly important in the coming decades, as climate change and land use are projected to intensify, both of which can substantially increase the potential for dust emissions and transport.

Figure 1

Schematic derived from satellite remote sensing images of 6-day transport of atmospheric dust from the Gobi Desert to the U.S. Pacific Coast during a massive dust storm in April 1998 (reprinted from Wilkening et al., 2000).

Figure 2

Illustration of environmental contaminant transport media, their transport times and spatial extent and their relative number of scientific peer-reviewed papers (low < 1,000 studies; high > 10,000 studies).

Figure 3

Natural and anthropogenic sources of dust associated with relative amounts of emissions, contaminant concentration, and risk to human health and the environment.

Figure 4

Factors influencing dust emissions by wind erosion and the environmental implications of dust emissions (reprinted from Ravi et al., 2011).

Figure 5

Coarse particulate emissions from (a) crushing and grinding and (d) wind erosion of mine tailings; fine particulate dust emissions from (b) smelting and (c) slag dumps. a. (SBM Machinery, 2010) b. (Listavia International, 2011) d. (Courtesy Blenda Machado, Mexico).

Figure 6

Idealized description of processes that affect atmospheric aerosol formation in three size ranges or modes – ultrafine (or Aitken), accumulation, and coarse (reprinted from Seinfeld and Pandis, 2006).

Figure 7

Plots of contaminant concentrations in roadside dust versus distance from the smelter stack (reference point), approximately the emissions of the industrial complex in Torreon, Mexico. (A) Arsenic; (B) cadmium; and (C) lead (reprinted from Benin et al., 1999).

Figure 8

Annual averaged Pb, As and Cd concentrations from MOUDI observations at the Hayden site for the period December 2008 through November 2009. Data represent average concentrations over thirty six 96-hour sampling periods; AF denotes after filter sample; error bars represent standard deviation of measurements (reprinted from Csavina et al., 2011).

Figure 9

Total multi-breath deposited particle fraction (solid lines) and regional deposition fraction in the extrathoratic, conducting, and pulmonary airways (dotted lines) (adapted from Park and Wexler, 2008).

Figure 10

Arsenic levels in soil of bare areas in yards, in interior floor dust and speciated urinary arsenic by proximity index of residence to smelter site (GM±GSE) (reprinted from Hwang et al., 1997).

Figure 11

A schematic representation of the deleterious impact of contaminants from emissions of mining operations on humans due to metal dose, taking into account relative metal concentrations around mining operations, deposition efficiency and location of deposition in the human respiratory system, and the distance traveled in the environment for the scope of human impact with US air quality regulations.