Jabiluka environmental studies

Morley, A. W.; Koontz, D. V.; Sanderson, N. T.

doi:10.1080/09593338409384252

Cited by 2 publications

(3 citation statements)

References 4 publications

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“…Major changes in the ionic dominance occur in Magela Creek billabong waters between the wet and dry seasons (Morley, 1981 ;Walker & Tyler, 1986;Hart et al, 1987). For Island billabong, the relative cation dominance during the 1981 dry season was little different to that found generally during the wet season, with dominance being Na > Mg > Ca > K. This order was also found by Walker & Tyler (1986).…”

Section: Conductivity and Major Ionssupporting

confidence: 64%

“…The most likely reason for the increase is that ingress of high sulphate groundwater occurred during this time, probably because the water level in the billabong was reduced to below the surrounding groundwater table. Ingress of high sulphate groundwater has also been suggested by Morley (1981), Walker & Tyler (1986) and Hart et al (1985aHart et al ( , 1987. Morley (1981) reported a sulphate concentration of 10 mg 1-' in groundwater from a bore approximately 50 m from the eastern bank of Island billabong.…”

Section: Physico-chemical Indicatorsmentioning

confidence: 73%

“…Ingress of high sulphate groundwater has also been suggested by Morley (1981), Walker & Tyler (1986) and Hart et al (1985aHart et al ( , 1987. Morley (1981) reported a sulphate concentration of 10 mg 1-' in groundwater from a bore approximately 50 m from the eastern bank of Island billabong. Groundwater from the flood-prone region to the south and west of this billabong has also been found to be acidic and to contain high concentrations of sulphate (Morley, 198 1 ;White & Gigliotti, 1982;Hart et al, 1987).…”

Section: Physico-chemical Indicatorsmentioning

confidence: 73%

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Biogeochemistry and effects of copper, manganese and zinc added to enclosures in Island Billabong, Magela Creek, northern Australia

1992

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Three large plastic enclosures (5 m diam, volume 40 m3) were used to study the effects of copper, manganese and zinc, on the phytoplankton community in Island billabong, a floodplain billabong (waterhole) situated in the Magela Creek in tropical northern Australia. Copper was added to one enclosure, and manganese and zinc to another, to give initial concentrations around ten times the normal wet season values. The enclosures and the billabong were monitored over a ten week period towards the end of the dry season, with the enclosures allowed to stabilise for four weeks before the metals were added.The control enclosure adequately simulated the temperature and pH changes in the billabong. The trends in conductivity, dissolved oxygen and major ion concentrations were similar in the enclosure and the billabong, with the minor differences observed attributed to either epiphytic growth on the enclosure walls (influenced dissolved oxygen, pH and bicarbonate concentration) or ingress of sulphate-rich groundwater into the billabong (influenced sulphate concentration and conductivity). Major differences in both the composition of species and the size of the phytoplankton populations were observed between the three enclosures and between the control enclosure and the billabong. This variability reflects the great natural variability in the phytoplankton communities in tropical lentic systems, and means that enclosures are unlikely to adequately simulate the biological communities in the billabongs.The control enclosure appeared to simulate quite well the longer term changes in total concentration and speciation of the three metals (copper, manganese & zinc) in the billabong. The mean concentrations of copper and zinc were similar in the two systems, although the mean concentration of manganese in the billabong was almost double that in the enclosure, possibly due to ingress of manganese-enriched groundwater. Particulate forms dominated the speciation of copper and manganese. There was considerable short term variation in both total metal concentration and speciation in both the enclosure and the billabong. This variability appears to be a feature of these small tropical waterbodies.The added heavy metals were found to have minimal detrimental effect on the phytoplankton community in each metal-loaded enclosure. The high natural variability in the phytoplankton community in these tropical systems will make it difficult to separate natural changes from those caused by low level contamination from mining operations should this occur.All three metals were rapidly removed from the water column, so that by the end of the six week period, only ca. 5 % of each added metal remained in the water column. Association with the particulate matter (phytoplankton, abiotic particulate matter and MnO, in enclosure 2) followed by sedimentation was the major removal pathway. Epiphytes growing on the enclosure walls appeared to have a minor influence (< 10% of the total amount of metal added) on the removal of the added metals. For copper, upt...

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Section: Conductivity and Major Ionssupporting

confidence: 64%

Section: Physico-chemical Indicatorsmentioning

confidence: 73%

Section: Physico-chemical Indicatorsmentioning

confidence: 73%

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Biogeochemistry and effects of copper, manganese and zinc added to enclosures in Island Billabong, Magela Creek, northern Australia

1992

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Manganese speciation in Magela Creek, northern Australia

Hart¹,

Noller²,

Legras³

et al. 1992

Mar. Freshwater Res.

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The speciation of Mn has been studied in Magela Creek, a tropical river in northern Australia containing water characterized by low pH, high temperature and extremely low ionic strength. Low concentrations (about 2-5�g L-1) of soluble Mn (i.e. filtration size <0.02�m) are typically found in these waters during the wet season, the main natural sources apparently being rainwater and groundwater. An additional source of soluble Mn has been identified, possibly being seepage from a mine retention pond. Rather surprisingly, the concentration of colloidal Mn (0.4-0.02�m) was almost three times higher than that of soluble Mn and was correlated with it. The primary process controlling the concentration of soluble Mn in this system appears to be rapid adsorption of soluble Mn to existing colloidal matter, followed by slower transfer of part of this surface-bound Mn to the interior of the colloid. Colloidal Mn is postulated to have a particularly long lifetime in this system because the removal process (aggregation to form particulate Mn) would be slow due to the extremely low concentrations of Ca and Mg ions during the wet season. A mixing experiment, undertaken to provide information on the possible fate of Mn in a mine retention pond if this wastewater should be discharged to the creek, clearly showed that Mn would be rapidly removed from the water column via colloidal and particulate forms. The precise mechanism was shown to be complex, depending upon the amount and characteristics of the colloidal and particulate matter present at the time of discharge, the changes in the Ca and Mg concentrations (which would influence the rate of aggregation), and the amount of turbulence in the creek.

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Jabiluka environmental studies

Cited by 2 publications

References 4 publications

Biogeochemistry and effects of copper, manganese and zinc added to enclosures in Island Billabong, Magela Creek, northern Australia

Biogeochemistry and effects of copper, manganese and zinc added to enclosures in Island Billabong, Magela Creek, northern Australia

Manganese speciation in Magela Creek, northern Australia

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