A retrospective assessment of gold mining in the Reedy Creek sub-catchment, northeast Victoria, Australia: residual mercury contamination 100 years later.

The mining of gold can lead to toxic metals such as mercury (Hg) contaminating watercourses as by-products. The Reedy Creek sub-catchment, in northeast Victoria, Australia, was mined for gold in the 1850s. In 1998, samples were taken from six watercourses to measure any remaining toxic metal contamination in sediments and surface waters from two creeks with no previous gold mining (controls) and four that were mined. Although mean concentrations of Hg (measured using an ICP-OES) in sediments were below worldwide background levels, individual sites along Reedy Creek had slightly elevated Hg concentrations. In contrast, the Hg concentrations in the surface waters were above background levels. Temporal fluxes of very high Hg concentrations in the surface waters during periods of first flow and flood events revealed that Hg concentrations in the surface waters may, at certain times of the year, exceed all Australian and New Zealand Environment and Conservation Council (National Water Quality Management Strategy. Australian Water Quality Guidelines for Fresh and Marine Waters, ANZECC, 2000) guidelines for water use and the protection of the aquatic ecosystem.

Occurrence, Parasitism, and Pathogenicity of Nematodes Associated with Sycamore (Platanus occidentalis L.).

Ten species of stylet-bearing nematodes were recovered in a survey of sycamore (Platanus occidentalis L. ) stands in Georgia. Helicotylenchus, Xiphinema, and Criconemoides were the genera found most frequently. Populations of Hoplolaimus galeatus, Scutellonema brachyurum, Helicotylenchus dihystera and H. pseudorobustus increased on greenhouse-grown sycamore, but Trichodorus christiei, Xiphinema americanum, Meloidogyne hapla, M. arenaria and M. incognita did not. Hoplolaimus galeatus and S. brachyurum are semi-endoparasites; H. dihystera and H. pseudorobustus are migratory endoparasites. Hoplolaimus galeatus caused extensive root necrosis and marked decrease of fresh weights of seedling roots and tops. Helicotylenchus dihystera and S. brachyurum produced only qualitatively different sparse and unhealthy root growth. Helicotylenchus pseudorobustus caused only a reduction in root surface area.