THE BIOAVAILABILITY OF COPPER AND MERCURY TO THE COMMON NETTLE (URTICA-DIOICA) AND THE EARTHWORM EISENIA-FETIDA FROM CONTAMINATED DREDGE SPOIL

The contaminants Hg and Cu, as well as Fe, Mn and K were sequentially extracted from upland disposed dredge spoil using DTPA and 10% nitric acid. Concentrations of these metals in aerial plant tissue and roots of Urtica dioica growing on the dredge spoil were also determined and used to correlate the biological absorption coefficients (BACs) and mo bile element absorption coefficients (MACs) with soil extractable meta ls. DTPA extractions were most suitable for prediction of aerial plant tissue uptake of Cu, Mn and K whilst total Hg and Fe soil concentrati ons were correlated with plant root BACs and MACs. A laboratory bioass ay using Eisenia fetida was also used to assess the potential biologic al uptake of the contaminants. Both Hg and Cu were accumulated by the worms, but interpretation of the results was hampered by the inherent difficulties of such active biomonitoring.