DOI: 10.5061/dryad.zgmsbccsc
title: Co-sampled fruticose and foliose epiphytic lichens as spatial biomonitors of airborne mercury and arsenic in a historical "Gold Rush" mining district

description: Historical gold mine tailings may have elevated total mercury (THg) and
 total arsenic (TAs) concentrations. We collected and analyzed the
 fruticose lichen genus Usnea and the foliose lichen genus Platismatia for
 biomonitoring airborne sources of Hg and As at the historical Montague
 Gold Mine District in Nova Scotia, Canada. We investigated spatial trends
 of Hg and As measured from 112 Usnea (10 species) and 113 Platismatia (2
 species) lichen thalli collected across four sampling grids covering both
 tailings and non-tailings areas. Usnea consistently had higher THg
 concentrations, while Platismatia showed higher TAs concentrations. Areas
 where there was evidence of known past mining activities (i.e. mine
 shafts, stamp mills, Hg-amalgamation sites) were found to be hotspots for
 both Hg and As in the lichen samples collected nearby. These areas likely
 received greater inputs of these elements from windblown tailings or
 volatilization processes, or indirectly from the interception of these
 elements by the forest edge/canopy adjacent to the tailings. A
 tailing-contaminated wetland at Montague was also identified as a hotspot
 for Hg, likely facilitating its redistribution into the atmosphere.
 Co-sampling of a fruticose and a foliose lichen can be an effective method
 for airborne monitoring of contaminants around historical mine tailing
 sites.
description: # Co-sampled fruticose and foliose epiphytic lichens as spatial
 biomonitors of airborne mercury and arsenic in a historical "Gold
 Rush" mining district Dataset DOI:
 [10.5061/dryad.zgmsbccsc](https://doi.org/10.5061/dryad.zgmsbccsc) ##
 Description of the data and file structure The goals of our research were
 (1) to assess the feasibility of co-sampling two morphologically different
 epiphytic lichens (fruticose vs foliose spp.) for biomonitoring airborne
 mercury (Hg) and arsenic (As) at the Montague gold mine tailings site in
 Nova Scotia, and (2) to investigate the fine-scale geospatial distribution
 patterns of Hg and As concentrations in the co-sampled lichens at Montague
 and interpret any spatial trends along a distance gradient from the
 tailings. Lichens (*Usnea* and *Platismatia* spp.) were sampled from
 spruce (*Picea* spp.) trees in July and August of 2019 across four
 sampling grids at Montague. Each sample was identified to the species
 level, homogenized, and analyzed for total mercury (THg) and total arsenic
 (TAs) concentrations. This raw data was then analyzed spatially in ArcGIS
 using interpolation modelling as well as other datasets and geoprocessing
 tools. ### Files and variables #### File: Raw_data_smith_et_al.zip
 **Description:** Raw mercury and arsenic concentration (μg/kg) data
 measured from *Usnea* and *Platismatia* lichens sampled at the Montague
 Gold Mining District, Nova Scotia, Canada. **Variables for**
 *Usnea_raw_data.csv* file: * **Site:** Site number or code, based on the
 georeferenced sampling points on Grids 1, 2, 3, and 4. The site numbers
 refer to sites (grid intersection points) on Grids 1-4. Specific site
 codes were used for some of our early lichen samples collected. These
 include: MO3 (Montague-3), MO2 (Montague-2), BR1 (Barry's Run), OSMA
 (Old Stamp Mill A), OSMB (Old Stamp Mill B), OSM1 (Old Stamp Mill 1), and
 MBRef (Mitchell Brook Reference).  * **Latitude:** Latitude coordinate
 where the lichen sample was collected, in decimal degrees. *
 **Longitude:** Longitude coordinate where the lichen sample was collected,
 in decimal degrees. * **Grid_Number:** Based on the sampling design, grid
 in which the site falls within (Grid 1, 2, 3, or 4). *
 **Distance_to_Nearest_Tailings_Edge:** The distance of each sampling site
 to the nearest tailings edge, in metres (m). Buffer polygons of 100 m were
 created around the Montague tailings layer, and each sampling site that
 fell within each buffer was denoted that distance category (e.g. On
 Tailings, 0-100m, 100-200m, 200-300m, and &gt;300m).  * **Land_Type:**
 Each sampling site was sorted into the corresponding land type (road
 corridor, natural forest stand, urban, wetland, treed bog, and wind
 throw), determined using the Nova Scotia Forest Inventory dataset
 ([https://novascotia.ca/natr/forestry/gis/dl_forestry.asp](https://novascotia.ca/natr/forestry/gis/dl_forestry.asp)). See the Figshare online resource for descriptions of each land type: [https://doi.org/10.6084/m9.figshare.22094969.v8](https://doi.org/10.6084/m9.figshare.22094969.v8).  * **Species:** *Usnea* species collected at the site, as identified from chemical spot tests. * ***Usnea*** **_THg_concentration:** Total mercury concentration measured in the collected *Usnea* sample (µg/kg). Missing values are populated with "NA". * ***Usnea*** **_TAs_concentration:** Total arsenic concentration measured in the collected *Usnea* sample (µg/kg). Missing values are populated with "NA". **Variables for** *Platismatia_raw_data.csv* file: * **Site:** Site number or code, based on the georeferenced sampling points on Grids 1, 2, 3, and 4. The site numbers refer to sites (grid intersection points) on Grids 1-4. Specific site codes were used for some of our early lichen samples collected. These include: MO2 (Montague-2), BR1 (Barry's Run), OSMA (Old Stamp Mill A), OSMB (Old Stamp Mill B), OSMC (Old Stamp Mill C), OSM1 (Old Stamp Mill 1), and MBRef (Mitchell Brook Reference).  * **Latitude:** Latitude coordinate where the lichen sample was collected, in decimal degrees. * **Longitude:** Longitude coordinate where the lichen sample was collected, in decimal degrees. * **Grid_Number:** Based on the sampling design, grid in which the site falls within (Grid 1, 2, 3, or 4). * **Distance_to_Nearest_Tailings_Edge:** The distance of each sampling site to the nearest tailings edge, in metres (m). Buffer polygons of 100 m were created around the Montague tailings layer, and each sampling site that fell within each buffer was denoted that distance category (e.g. On Tailings, 0-100m, 100-200m, 200-300m, and &gt;300m).  * **Land_Type:** Each sampling site was sorted into the corresponding land type (road corridor, natural forest stand, urban, wetland, treed bog, and wind throw), determined using the Nova Scotia Forest Inventory dataset ([https://novascotia.ca/natr/forestry/gis/dl_forestry.asp](https://novascotia.ca/natr/forestry/gis/dl_forestry.asp)). See the Figshare online resource for descriptions of each land type: [https://doi.org/10.6084/m9.figshare.22094969.v8](https://doi.org/10.6084/m9.figshare.22094969.v8).  * **Species:** *Platismatia* species collected at the site, as identified from chemical spot tests. * ***Platismatia*** **_THg_concentration:** Total mercury concentration measured in the collected *Platismatia* sample (µg/kg). * ***Platismatia*** **_TAs_concentration:** Total arsenic concentration measured in the collected *Platismatia* sample (µg/kg). Missing values are populated with "NA". ## Access information Other publicly accessible locations of the data: * [https://arcg.is/zCa1H](https://arcg.is/zCa1H)