title: Thresholds of copper phytotoxicity in field-collected agricultural soils exposed to copper mining activities in Chile.
abstract: It has been argued that the identification of the phytotoxic metal thresholds in soil should be based on field-collected soil rather than on artificially-contaminated soils. However, the use of field-collected soils presents several difficulties for interpretation because of mixed contamination and unavoidable covariance of metal contamination with other soil properties that affect plant growth. The objective of this study was to estimate thresholds of copper phytotoxicity in topsoils of 27 agricultural areas historically contaminated by mining activities in Chile. We performed emergence and early growth (21 days) tests (OECD 208 and ISO 11269-2) with perennial ryegrass (Lolium perenne L.). The total Cu content in soils was the best predictor of plant growth and shoot Cu concentrations, while soluble Cu and pCu(2+) did not well correlate with these biological responses. The effects of Pb, Zn, and As on plant responses were not significant, suggesting that Cu is a metal of prime concern for plant growth in soils exposed to copper mining activities in Chile. The effects of soil nutrient availability and shoot nutrient concentrations on ryegrass response were not significant. It was possible to determine EC10, EC25 and EC50 of total Cu in the soil of 327 mg kg(-1), 735 mg kg(-1) and 1144 mg kg(-1), respectively, using the shoot length as a response variable. However, the derived 95% confidence intervals for EC10, EC25 and EC50 values of total soil Cu were wide, and thus not allowing a robust assessment of metal toxicity for agricultural crops, based on total soil Cu concentrations. Thus, plant tests might need to be performed for metal toxicity assessment. This study suggests shoot length of ryegrass as a robust response variable for metal toxicity assessment in contaminated soils with different nutrient availability.
authors.affiliation: Escuela de Agronomía, Pontificia Universidad Católica de Valparaíso, Casilla 4-D, Quillota, Chile.
authors.forename: José
authors.initials: J
authors.lastname: Verdejo
authors.affiliation: Departamento de Ecosistemas y Medio Ambiente (DEMA), Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago, Chile; Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Ginocchio
authors.affiliation: Department of Chemistry, Université de Montréal, Montréal, QC, Canada H3C 3J7.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.affiliation: Escuela de Agronomía, Pontificia Universidad Católica de Valparaíso, Casilla 4-D, Quillota, Chile.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Salgado
authors.affiliation: Escuela de Agronomía, Pontificia Universidad Católica de Valparaíso, Casilla 4-D, Quillota, Chile. Electronic address: alexander.neaman@ucv.cl.
authors.forename: Alexander
authors.initials: A
authors.lastname: Neaman
mesh_terms: D000383:Agriculture; D002677:Chile; D003300:Copper / Q000633:toxicity*; D000075322:Heavy Metal Poisoning; D008129:Lolium / Q000187:drug effects* / Q000254:growth & development; D008906:Mining; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D011041:Poisoning; D012987:Soil; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D003300:Copper
keywords: Bioavailability; Cu; Ryegrass; Toxicity