Contamination of habitats with heavy metals has become a worldwide problem. We describe herein the analysis of lake sediment contaminated with high concentrations of copper as a consequence of mine milling disposal over a 100-year period. Copper concentrations in the sediment were found to vary with depth and ranged from 200 to 5500 ppm. Analysis of the microbial community with T-RFLP identified a minimum of 20 operational taxonomic units (OTU). T-RFLP analysis along a depth profile detected as many as nine shared OTUs across 15 centimeters, suggesting a conservation of community structure over this range. Only two genera, Arthrobacter and Ralstonia, were detected among 50 aerobic copper-resistant isolates cultivated on R2A, one of which (Ralstonia sp.) was characterized by the sequestration of copper, identified by electron diffraction scanning, in growing colonies. Scanning electron microscopy showed changes to the outer envelope of the cells when grown in the presence of copper. The copper-resistant Ralstonia isolates were also resistant to Ni, Cd, and Zn, showing two patterns of phenotypic resistant to these three metals in which either resistance to Zn or Ni was expressed in an isolate but never both.

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This paper examines the hypothesis that the spatial pattern of metal accumulation rates in inland lake sediments provides insight into the causes of the historical and continued loadings of contaminants to the environment. To address this, copper and lead accumulation rates in the Great Lakes' watershed were studied. A multi‐element approach was used, in which many non‐toxic chemicals were measured along with the toxic chemicals of interest, rather than a target‐specific approach. The multi‐element approach also allowed for assessing the environmental state of the lake with respect to its surrounding watershed. Sediment cores were collected from the deepest portion of five Michigan inland lakes, sectioned, metals extracted by nitric acid, microwave digestion and leachates analysed for 26 metals using an inductively coupled, plasma, mass spectrometer with hexapole technology. Sedimentation rates, ages and focusing factors were calculated via 210Pb. Dasymetric mapping was used to estimate population distributions in lake watersheds. Watershed area was estimated from digital elevation data using Arc/INFO (ESRI, Redlands, California). The data show that as loadings from dominant (regional) sources decrease (e.g. atmospheric deposition in the case of lead), new patterns provide insight into causes for continued contaminant loadings (e.g. population density). The data also show the universal response of the watersheds to the onset of the anthropogenic loadings of lead but not that of copper. Individual watersheds had different onset times for anthropogenic copper loadings. Recent lead loadings to the environment can be related to population density, and those of copper reflect, in part, a spatial pattern that is similar to the regional pattern for lead during the mid‐1970s. As this pattern for lead could be related to a regional gradient of lead concentrations in atmospheric deposition, the same relation cannot be made for copper. The cause for this spatial pattern for copper is not clear.