NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: contaminants, mining, arsenic, berries, garden produce

Objective(s): To gain a better understanding of the current state of mining related contaminants in local berries and garden produce in the Yellowknife area and to determine the potential risk to human health associated with the consumption of these local food sources.

Project Description: This licence has been issued for the scientific research application No.4829. The objective of this project is to gain a better understanding of the current state of mining related contaminants in local berries and garden produce in the Yellowknife area and to determine the potential risk to human health associated with the consumption of these local food sources. Specifically, this project aims to determine concentrations of arsenic and other mining associated metal(loid)s in berries, garden produce and associated soils from the Yellowknife region. The research team will investigate relationships between soil and food source concentrations of mining associated metal(loid)s to support the mechanistic understanding of contaminant uptake. The team will then evaluate the spatial distribution of arsenic and other mining associated metal(loid)s in local berries from the Yellowknife region to identify potential areas of concern, and to apply nationally accepted risk assessment protocols to estimate risk to public health from consumption of local foods to Yellowknives Dene First Nation (YKDFN) members and residents of Yellowknife. The 2020 Fall season will include berry sampling. Berry samples will be collected from 50 locations with varying distance and direction from historic mining roasters within a 50 km radius of Yellowknife. Soil samples will be collected at each berry collection location to assess relationships between levels of metal(loid)s in berries and associated soils. 50 locations x 2 sample types (berries and soils) = 100 samples (+ 10% duplicates or split samples) = 110 samples. Garden produce will be collected from 20 gardens in the Yellowknife region, including community gardens. Gardens will be specifically targeted in the communities of Ndilo and Detah. Soil samples will be collected by project team members from each garden plot to determine the concentration of mining associated metal(loid)s in soils and the predominant As-hosting minerals. Sampling of garden produce in the first year will target a wide variety of vegetables to assess difference in bioaccumulation of metal(loid)s between vegetables. Sampling in subsequent years will focus on most common vegetables and vegetables with highest accumulation factors (likely leafy greens). Year 1: 20 gardens x 5 vegetable types = 100 samples (+ 10% duplicate or split samples) = 110 vegetable samples. Year 2: 20 gardens x 3 vegetable types = 60 samples (+ 10% duplicate or split samples) = 66 vegetable samples. The 2020 to 2021 Winter season will include laboratory analyses. Soils, berries, and produce will be prepared for total metals analysis by inductively coupled plasma mass spectrometry (ICP-MS) at the Analytical Services Unit at Queen’s University. Samples will be freeze dried and digested using an aqua regia digestion. As, Se (selenium), and Cr (chromium) speciation in berries and garden produce will be conducted using the optimized methods developed in the winter of 2020, and will include bioaccessibility measurements. As bioaccessibility and phytoavailability in soils will be determined by using standard methods for bioaccessibility (U.S. EPA 2017) and methods (obtained through literature review) of phytoavailability estimates. Arsenic speciation in 20 soil samples from gardens and berry locations will be determined using SEM paired with an automated mineralogy technique (SEM-MLA) at the Jamieson laboratory at Queen’s University. The 2021 Spring season will include field planning for year 2; additional areas to target for berries; additional gardens to target and repeat sampling from several gardens; and reporting of results from first year of the study to YKDFN members and garden owners. Regular contact will occur between project team members, including frequent email, phone and in-person meetings. ARI and YKDFN staff are located in Yellowknife which will facilitate knowledge sharing. In Winter 2020 the results that are available from the first field sampling program will be shared with staff from the Department of Lands and Environment at the YKDFN as a short 1- or 2-page summary. Results from individual garden plots will be shared with plot owners and will be associated with a short letter with preliminary interpretation of the results. Note, final results including the risk assessment portion of the work will not be available until the conclusion of the project. Results from the second year of the study will be shared with YKDFN staff through a 1- to 2- page report. This report will be followed up by an in-person presentation to YKDFN and interested members in Ndilo or Dettah. Project results will be presented at the Yellowknife Geoscience Forum and one other national or international conference. Project team members will work with the Department of Health and Social Services and local non-governmental organizations with an interest in gardening to develop a fact sheet for gardeners that includes a summary of the project results and recommendations for methods to reduce exposure to contaminants of concern through garden produce. Projects results will be shared at a series of community meetings in Yellowknife, Ndilo, and Detah. The fieldwork for this study will be conducted from September 23, 2020 to December 31, 2020.