<i>BIOMARKERS AT LEVEL OF A GRASSLAND COMMUNITY AND A FORAGE POPULATION FOR SOILS POLLUTED BY COPPER</i>

Abstract

This report discusses several factors that may be considered biomarkers of the effects of soil Cu at two levels of biological organisation. Based on potential implications for trophic systems, this investigation was performed on a pasture community used by cattle and a forage leguminous population. The study area was a 3.500 m3 slag heap in the Madrid province corresponding to a copper pyrite mine in disuse for 37 years. Once the content of absorbable Cu of the tip and surrounding contaminated soil had been established, 3 Kg top soil samples were obtained from 5 areas showing Cu levels of 42, 254, 654, 1153and 2500 ppm. The soil samples were placed in 22 x 15 x 8 cm containers, in triplicate for each Cu level, to perform the following bioassays under controlled, greenhouse conditions: (i) monitoring plant cover growth from seed-bank seeds for 8 weeks; (ii) seeding of the legume Lupinus albus cv. Multolupa until flowering (12 weeks). Soil from the same area but unaffected by the mine (5 ppm Cu) was used as the control. Herbaceous % coverage was the main biomarker used for the plant community and the variables: plant height, leaf diameter, foliole length and width, plant vigour and incidence of leaf necrosis were used as markers of the effects on the fodder population. The data obtained were subjected to analysis of variance using SPSS software. Findings suggest that plant coverage may be considered a biomarker of the Cu content of soils of high Cu concentration, particularly after the seventh week. The morphological characters of the forage population (especially incidence of leaf necrosis) also proved to be good biomarkers of Cu. Contaminating effects of absorbable Cu were best shown by the plant population.