title: Soil amendment affects Cd uptake by wheat - are we underestimating the risks from chloride inputs?
abstract: Many parts of the world are investigating the efficacy of recycling nutrient resources to agriculture from different industry and domestic sectors as part of a more circular economy. The complex nature of recycled products as soil amendments coupled to the large diversity of soil types and their inherent properties make it difficult to optimize the benefits and minimize the risks from potentially toxic elements often present in recycled materials. Here we investigated how wheat grain cadmium (Cd) concentration was affected by soil amendments, namely human urine and biogas digestate compared to traditional farm manures and mineral fertilizers. We show that Cl(-) inadvertently added to soils with e.g. urine or biogas digestate strongly increased crop Cd concentrations, largely by mobilizing inherent soil Cd. This resulted in wheat grain Cd levels that could result in exceeding recommended WHO limits for dietary intake. This was evident even in soils with low inherent Cd content and when Cd inputs were low. The future of a circular economy that helps to underpin global food security needs to ensure that the effects of applying complex materials to different types of agricultural land are fully understood and do not jeopardize food safety.
authors.affiliation: Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden. Electronic address: Sigrun.Dahlin@slu.se.
authors.forename: A Sigrun
authors.initials: AS
authors.lastname: Dahlin
authors.affiliation: Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden. Electronic address: Jan.O.Eriksson@slu.se.
authors.forename: Jan
authors.initials: J
authors.lastname: Eriksson
authors.affiliation: Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden; The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, Scotland, UK. Electronic address: Colin.Campbell@hutton.ac.uk.
authors.forename: Colin D
authors.initials: CD
authors.lastname: Campbell
authors.affiliation: Department of Crop Production Ecology, Swedish University of Agricultural Sciences, P.O. Box 7043, SE-750 07 Uppsala, Sweden; World Agroforestry Centre (ICRAF), UN Avenue, P.O. Box 30677-00100, Nairobi, Kenya. Electronic address: Ingrid.Oborn@slu.se.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Öborn
mesh_terms: D000383:Agriculture / Q000379:methods*; D002104:Cadmium / Q000032:analysis / Q000378:metabolism*; D002712:Chlorides / Q000737:chemistry*; D004784:Environmental Monitoring; D005308:Fertilizers; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D014908:Triticum / Q000378:metabolism*
chemical_list: D002712:Chlorides; D005308:Fertilizers; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium
keywords: Cadmium mobility; Chloride complexation; Circular economy; Human health; Nutrient recovery; Wastes