Differential accumulation of PAHs, elements, and Pb isotopes by five lichen species from the Athabasca Oil Sands Region in Alberta, Canada

Abstract

A 2014 case study investigated the relative accumulation efficiency of polycyclic aromatic hydrocarbons (PAHs), total sulfur (S), total nitrogen (N), major and minor elements and Pb isotopes in five common lichen species at three boreal forest sites in the Athabasca Oil Sands Region (AOSR) in northeastern Alberta, Canada to identify the optimum lichen species for future biomonitoring. Differences in concentrations of PAHs, multiple elements, and Pb isotopes in fruticose (Bryoria furcellata, Cladina mitis, Evernia mesomorpha) and foliose (Hypogymnia physodes and Tuckermannopsis americana) lichens were found along a 100 km distance gradient from the primary oil sands operations. Integration of insights from emission source samples and oil sands mineralogy in consort with aerosol collection indicates incorporation of more fine particulate matter (PM) into foliose than fruticose lichen biomass. Contrasting PAH with element concentrations allowed lichen species specific accumulation patterns to be identified. The ability of lichen species to incorporate different amounts of gas phase (S and N), petrogenic (V, Ni, Mo), clay (low Si/Al and more rare earth elements), and sand (higher Si/Al and Ti) components from the oil sand operations reflects aerosol particle size and lichen physiology differences that translate into differences in PM transport distances and lichen accumulation efficiencies. Based on these findings Hypogymnia physodes is recommended for future PAH biomonitoring and source attribution studies.

Bog plant/lichen tissue nitrogen and sulfur concentrations as indicators of emissions from oil sands development in Alberta, Canada

“…Concentrations of N and S in C. mitis tissues were positively correlated with spatial patterns of atmospheric N and S deposition in the Alberta oil sands region (Wieder et al, 2016a). However, tissue N and S responses to a gradient in N and S deposition were reported to be substantially stronger for E. mesomorpha than for C. mitis (Graney et al, 2017).…”

“…Lichens have long been recognized as potentially useful indicators of atmospheric N and S pollution (e.g. Hawksworth & Rose, 1976;Pinho et al, 2017;Will-Wolf et al, 2017) as well as within the Alberta sands region (e.g., Graney et al, 2017;Landis et al, 2012Landis et al, , 2019. Evernia mesomorpha has been shown to be very sensitive to even shortterm exposure to low doses of SO 2 , which reduces net CO 2 assimilation and respiration rates as well as protein and lipid biosynthesis (e.g., Huebert et al, 1985;Malhotra & Khan, 1985).…”

Air synthesis review: polycyclic aromatic compounds in the oil sands region

“…Initially the lichen studies focused on total nitrogen and total sulfur deposition then expanded to elements and PACs. Hypogymnia physodes (H.physodes) was determined to be the optimum species for the collection and retention of PACs (Graney et al 2017), and methods for the collection, extraction, and analysis of H.physodes samples for PACs using single quadrupole mass spectrometry (GC-SIM-MS) were developed (Studabaker et al 2017). An initial pilot study involving the selection of a subset of 20 of the 2008 campaign H.physodes samples collected from jack pine (Pinus banksiana) and black spruce (Picea mariana) host trees found (i) the sum of measured PAH congener concentrations (⌺PAH) ranged from 52-352 ng/g; (ii) PHE and naphthalene were the predominant species present with median concentrations of 22.1 and 18.0 ng/g, respectively; (iii) the highest concentrations were observed in close proximity (<40 km) to the OS mining and upgrading operations; and (iv) PAC concentrations declined following a roughly inverse square root to distance function (Studabaker et al 2012).…”

Are we accurately estimating the potential role of pollution in the decline of species at risk in Canada?

“…For example, many lichen species have received a scope of large for Air-Borne Pollutants, even though they rarely co-occur with point sources of this pollution category. Experts in these cases may have factored in the well-known ability of air pollutants to disperse over immense distances, and the documented accumulation of atmospheric contaminants in lichens, in assessing the scope of this pollution category (e.g., Carignan et al 2002;Graney et al 2017). Our analysis shows that species at risk and pollution sources co-occur at a high rate in Canada.…”