A cross-regional ecological assessment of contaminants in soils intended for agri-food initiatives on Indigenous Peoples’ lands in Australia and Canada

Abstract

Globally, soil contamination threatens ecosystems and food security. This study examines the contamination of soils intended for agri-food initiatives by Indigenous communities across New South Wales and Queensland, Australia, and Newfoundland and subarctic Ontario, Canada. Soils from 47 sites were tested for metals, metalloids, organochlorine (OC) pesticides, and polychlorinated biphenyls (PCBs) to assess ecological risks and compare against national guidelines. Australian soils were primarily contaminated with lead (Pb) and to a lesser extent with other metals and metalloids, whereas subarctic Ontario soils were heavily contaminated with OC pesticides, and to a lesser extent metals and metalloids. Newfoundland soils contained arsenic (As) concentrations exceeding agricultural soil guidelines with limited OC levels. The contaminants from these sites stem from both anthropogenic activities and natural geological sources; however, their precise origins—whether from the historical use of banned substances or mineral extraction—are not fully elucidated for all sites. This article specifically highlights the need to assess soil to be used in agri-food initiatives for contaminants in rural and remote landscapes in Indigenous homelands worldwide and, in general, for all soil to be used in any agri-food initiative.