THE RELATIONSHIP BETWEEN METAL CONCENTRATION AND ORGANIC-MATTER IN SEDIMENTS AND METAL CONCENTRATION IN THE AQUATIC MACROPHYTE ERIOCAULON SEPTANGULARE

Sediment cores and samples of the submerged and rooted isoetid Eriocau lon septangulare (With.) were used to examine the relationships betwee n the concentrations of Hg, Pb, Cd and Fe in plants, and metal concent rations and organic matter (OM) content of sediments. Thirteen sites i n the littoral zone of Bentshoe Lake, a softwater lake of the Muskoka- Haliburton region of south-central Ontario were included in the study design. Metal concentrations in sediments ranged from 0.007 to 0.247 m u g g(-1) for Hg, 2.8 to 167.6 mu g g(-1) for Pb, 0.06 to 2.53 mu g g( -1) for Cd and 2.55 to 34.77 mg g(-1) for Fe. There were significant p ositive correlations between metal concentrations in sediment and OM c ontent. Metal concentrations measured in Eriocaulon septangulare were generally comparable to or higher than those in sediments, and for eac h respective metal, were consistently higher in the roots than in the shoots. Concentrations of metals in E. septangulare ranged (dry weight , leaf concentration listed first and roots second for each metal) fro m 0.03 to 0.22 mu g g(-1) for Hg, from 2.6 to 62.8 mu g g(-1) for Pb, from 0.58 to 13.33 mu g g(-1) for Cd and from 0.61 to 156.20 mg g(-1) for Fe. Metal concentrations in the roots and in the leaves were signi ficantly positively correlated for Hg, Cd and Fe. Metal concentrations in the roots were not correlated with metal concentrations in the sed iments. The presence of high concentrations of organic matter (OM) in sediments is shown to decrease the availability of metals to E. septan gulare. However, when the total metal concentrations in sediments were normalized for organic content, there was a significant correlation w ith metal in the plant for Hg, but not for the other metals under cons ideration.