Browsing by Author "Goodman, AE"

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    Microbial ecology of Rum Jungle II: environmental study of two flooded opencuts and smaller, associated water bodies.
    (Australian Atomic Energy Commossopm, 1981-12) Goodman, AE; Khalid, AM; Ralph, BJ
    The microbial status of the flooded Intermediate and White's opencuts of the abandoned uranium mine at Rum Jungle was investigated by sampling the water column and sediments of several areas in each opencut. Smaller water bodies associated with the experimental heap-leach pile were also investigated. Several groups of bacteria were identified and population sizes were estimated using selective media techniques. Various physicochemical parameters of each sample were determined and correlated with the occurence of bacteria. Both opencuts although behaving differently were found to be heavily polluted by sulphuric acid and heavy metals White's more so than Intermediate. White's opencut was found to be stratified into an aerobic zone about five metres deep and a microaerophilic zone below this. Large populations of Thiobacillus ferrooxidans and autotrophic sulphur-oxidising bacteria indicated that degradation of sulphidic minerals in the walls and floors of the opencuts was still occurring. The isolation of T. ferrooxidans from sediments also containing anaerobic bacterial species suggested that T. ferrooxidans was degrading sulphidic minerals either anaerobically or microaerophilically. The smaller water bodies also were found to be heavily polluted by acid and heavy metals from drainage and seepage from the sulphidic heap-leach pile.
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    Microbial ecology of Rum Jungle III : leaching behaviour of sulphidic waste material under controlled conditions
    (Australian Atomic Energy Commission, 1981-12) Babij, T; Goodman, AE; Khalid, AM; Ralph, BJ
    The discharge into river systems of acid and heavy metals generated by leaching of sulphidic waste materials at the abandoned opencut uranium mine at Rum Jungle Northern Territory is causing continuing pollution of the surrounding environment. The maximum effects of acid and microorganisms on samples from the overburden dump material under defined and controlled environmental conditions were assessed using reactor systems. These samples came from the overburden dump resulting from the mining of White's orebody. Similarly the stability of tailings material under conditions of flooding and increasing acidity was determined. At ph 2.5 metals in White's dump material were solubilised by acid attack only whereas at pH 3.5 bacterial activity (principally that of Thiobacillus ferrooxidans) generated acidity and contributed significantly to metal release. Under microaerophilic conditions Thiobacillus ferrooxidans continued to effect metal release from the ore but did not produce further acidity. If White's overburden is returned to the acidic flooded opencuts complete solubilisation of the material will occur. The exclusion of oxygen from the dump will not necessarily stop bacterially catalysed leaching processes. Under highly aerated and agitated flooded conditions the tailings material was not active except for copper release of about 2 g kg -1 ore at pH 4.0. The only deleterious element released by increasing acidity was copper which was 100 per cent solubilised at pH 2.5. Uranium was always lss than 3 mu g kg -1 ore and lead was detected only at pH 2.5. Indigenous leaching bacteria did not develop.
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    Microbial ecology of Rum Jungle, Part I. - environmental study of sulphidic overburden dumps, experimental heap-leach piles and tailings dam area.
    (Australian Atomic Energy Commission, 1981-12) Goodman, AE; Khalid, AM; Ralph, BJ
    The microbial ecology of the abandoned uranium mine at Rum Jungle, Northern Territory, was investigated to determine the nature and extent of microbial populations occurring in sulphidic waste areas. Several groups of bacteria were identified and population sizes were estimated, using selective media techniques. Various physicochemical parameters of each sample were determined and correlated with the occurrence of bacteria. A medium giving a high percentage recovery of Thiobacillus ferrooxidans colonies was developed. Sulphidic waste areas were found to support a large and diverse microbial flora, with T. ferrooxidans consistently occurring, although microorganisms were isolated only from the far eastern end of the tailings dam area. In White's dump, relatively low numbers of T. ferrooxidans and high numbers of acidophilic heterotrophs occurred with no seasonal variation, whereas sulphur-oxidising bacteria were absent at the end of the dry season and increased to high numbers during the wet. Desulfovibrio spp. were isolated only from a zone, less that one metre high, at the very base of the dump within which conditions otherwise were aerobic. The dump supported different microbial populations in localised areas and, in two areas where T. ferrooxidans was virtually absent, little pyritic oxidation appeared to be occurring. Intermediate dump was found to differ significantly from White's. T. ferrooxidans was the major microbial species, numbers of which increased from the end of the wet season to the early dry. Other bacterial types were scarce and no anaerobic bacteria was isolated. Relatively crude temperature measurements indicated that, in the top of the dump, pyritic oxidation may be occurring more homogeneously and at higher rates than in White's dump.