Phytotoxicity and bioaccumulation of copper and chromium using barley (Hordeum vulgare L.) in spiked artificial and natural forest soils

The toxicities of two heavy metals, copper (Cu2+) and chromium (Cr6+), to barley (Hordeum vulgare L.) were evaluated using two types of substrates: artificial and natural forest soils. Phytotoxicity was assessed using a standardized toxicity test. Endpoints included plant emergence and shoot and root growth. Shoot and root concentrations of Cu and Cr were also measured. Data indicated that the root biomass was the most sensitive endpoint. The results showed that toxicity of Cr to root growth (IC50 = 6.6 mug/g in artificial soil; IC50 = 61.8 mug/g in forest soil) was higher than that of Cu (IC50 = 13.7 mug/g in artificial Soil; IC50 > 322 mug/g in forest soil). Data also indicated that the toxicity of Cu and Cr was significantly decreased in the spiked forest soil, suggesting lower metal bioavailability to barley in the natural soil. Analysis of tissue concentrations in barley showed that Cu and Cr were mainly accumulated in the roots. Toxicity was correlated with Cr residues in shoots (less than or equal to 11.2 mug Cr/g and less than or equal to 5.3 mug Cr/g for artificial and natural soils, respectively) and roots (less than or equal to 161 mug Cr/g and less than or equal to 51.7 mug Cr/g for artificial and natural soils, respectively) and Cu residues in roots (less than or equal to 61.8 mug Cu/g and less than or equal to 91.3 mug Cu/g for artificial and natural soils, respectively). Cu concentration in shoot tissues was less than or equal to 61.8 mug Cu/g. Since it may overestimate toxicity, effect and risk assessment using spiked soils, particularly in artificial soil, must be used with diligence. (C) 2003 National Research Council of Canada. Published by Elsevier Inc. All rights reserved.