A COMPARATIVE-STUDY OF PB, CU, AND CR IN ROADSIDE SEDIMENTS IN METROPOLITAN LAGOS AND BENIN-CITY, NIGERIA

The effect of motor vehicle emissions containing the trace elements Pb, Cu, and Cr in surface sediments is investigated along motor routes in metropolitan Lagos and Benin City in southwestern Nigeria. The results of analyses of 85 sediment samples from roadside drains, 60 from metropolitan Lagos and 25 from Benin City, show clear differences in pollution levels between the two cities. There are proportionately high Pb, Cu, and Cr concentrations in sediments along high density motorways in both cities considered while lower trace metals are found along medium and light density motorways. However, there are higher levels of trace metal enrichment in Benin City than in Lagos. In particular, high levels of Pb (480-5112-mu-g/g, mean: 1207 +/- 35) are found in sediments along high density motorways in Benin City in comparison to 221-1252-mu-g/g (mean: 540 +/- 82) recorded for Lagos samples. The generally higher trace metal concentrations in Benin City are inferred to result from very poor municipal drainage systems.