Abstract
ROADSIDE EARTHWORM CAST AND LEAVES AS BIO - INDICATORS OF TRAFFIC RELATED PB AND CU POLLUTION IN MAKURDI - NIGERIA

This study assessed the eligibility of earthworm casts and the leaves of plants as bio – indicators of heavy metal contamination. Earthworm casts and leaves of plants were collected systematically from every 5 m interval up to 60 m away from the road. Two roads were considered namely: Yogbo and Lafia while Cu and Pb were considered for analysis. All samples were digested using the aqua regia (HNO3 and HCl; 1:3) digestion. A flame atomic absorption spectrophotometer (Buck Scientific 200A) was used in analyzing samples. The result showed that the concentrations of Cu and Pb decreased steadily as the distance away from the road increased in soil, leaves and casts. A maximum transfer factor of 0.85 was obtained for Cu in the soil – leaves component while 0.87 was obtained for the soil – casts counterpart while for Pb the maximum transfer factor was 0.81 in casts and 0.7 in leaves. This implies that the amount of transfer of metal was higher in casts than leaves. Comparisons between the content of these metals between the two sample areas showed that the Lafia road sample point had a higher concentration of Cu and Pb and both the casts and the leaves also showed that the concentration of the metals was more in the Lafia sample area occasioned by high vehicular traffic implying that casts and leaves of plants are good indicators of heavy metal pollution.