Natural enrichment of topsoils with chromium and other heavy metals, Port Macquarie, New South Wales, Australia

摘要: Total heavy metal concentrations [cobalt (Co), chromium (Cr), copper(Cu), iron (Fe), mangnese (Mn), nickel (Ni), lead (Pb), and zinc (Zn)]were determined in surface soil samples from Port Macquarie, New South Wales,Australia. Composite topsoil (0–10 cm depth) had mean values(per kg) of 13 mg Co, 1020 Cr, 59 Cu, 136·7 g Fe, 719 Mn, 149mg Ni, 20 Pb, 47 Zn. The topsoils were generally characterised by alow pH (3·8–5·2) a mineralogy dominated haematite,magnetite, quartz, kaolinite. Chromium was predominantly present thetopsoils as Cr3+ microcrystalline chromite(FeCr2O4) and, to lesser degree,in kaolinite haematite. Differences Cr with depthwere due variations the relative abundance various soilcomponents, rather than mobility within soilprofile. elevated are result soildevelopment over metal-rich bedrock (serpentinite matrix melange) andassociated enrichment relatively immobile elements (Cr, Ni) theresidual profile. ANZECC NH&MRC (Australian ZealandEnvironment Conservation Council National Health & MedicalResearch Council) environmental investigation limits exceeded for100% sample sites for 47% 61% Mn,and 58% Ni.