ABSTRACT
ORGANIC MATTER REDUCES COPPER TOTOXICITY FOR THE EARTHWORM Eisenia fetida IN SOILS FROM MINING AREAS IN CENTRAL CHILE

Gonzalo Ávila1, Hernán Gaete2, Sébastien Sauvé3, and Alexander Neaman1, 4*
 
The Aconcagua River basin (Central Chile) is one of the most important agricultural areas in the country. However, several copper (Cu) mining operations are located in the basin. The objective of the study was to determine Cu toxicity for the earthworm Eisenia fetida (Savigny 1826) in the agricultural soils of the basin. We determined the production of cocoons and juveniles of earthworms in the studied soils. The soils differed in the concentrations of organic matter (OM, range 2-6%), pH (range 7.3-8.3), texture (from loamy sand to clay loam), and total Cu concentrations (range 230-960 mg kg-1). Concentrations of Cu and OM in the soils were the variables that determined the earthworms’ biological response. In contrast, pH and texture did not affect this response. Cocoon and juvenile production decreased considerably in soils with elevated Cu concentrations (> 500 mg kg-1), regardless of OM concentrations. Cocoon production decreased in the soils with Cu concentrations below 500 mg kg-1 when OM concentrations were below 3.5%. In contrast, cocoon production did not vary when OM concentrations were above 3.5%. The same effect of OM was observed on juvenile production. In this case, the threshold for OM concentration was 2.5%. It was concluded that it is important to consider OM concentrations in order to predict the biological response of earthworms in these soils.
Keywords: Eisenia fetida, Aconcagua River, ecological risk assessment, Cu mining, trace elements.
1 Pontificia Universidad Católica de Valparaíso, Facultad de Agronomía, Casilla 4-D, Quillota, Chile. * Corresponding author (alexander.neaman@ucv.cl). 2 Universidad de Valparaíso, Facultad de Ciencias, Av. Gran Bretaña 1111, Valparaíso, Chile. 3 Université de Montréal, Département de Chimie, CP 6128 Centre-ville, Montréal, QC, H3C 3J7, Canada. 4 Centro Regional de Estudios en Alimentos Saludables (CREAS), Blanco 1623, Of. 1402, Valparaíso, Chile.