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Lake Manapouri, widely regarded as one of NZ's most beautiful lakes. This one of the many pristine lakes in the South Island that have been studied by the MFC group. |
Publications relating to lakes
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Lake Manapouri, widely regarded as one of NZ's most beautiful lakes. This one of the many pristine lakes in the South Island that have been studied by the MFC group. |
Zinc speciation in Lakes Manapouri and Hayes, New Zealand. Ellwood, M, Hunter, K.A and Kim, J.P. (2000). Marine and Freshwater Research 52: 217-222.
A preliminary study of zinc complexation in Lakes Manapouri and Hayes revealed that zinc speciation in both lakes is dominated by its complexation to natural organic ligands. For Lake Manapouri dissolved zinc concentrations increased from 0.9 nM in surface waters to ~1.4 nM at depth. Ligand concentrations for this lake were relatively uniform with depth with values ranging between 2.9 and 4.2 nM. A similar ligand concentration was measured for Lake Hayes which had a surface zinc concentration of 3.1 nM. Conditional stability constants (log K) for the complexation zinc to these ligands were high with values ranging between 10.0 and 11.1. Calculated free Zn(II) concentrations for both lakes were in the low picomolar range. Such low free Zn(II) levels may limit the growth of some phytoplankton in both lakes..
Trace metal and major ion compositions of Lakes Hayes and Manapouri. Reid, M. R., Kim, J. P. and Hunter, K.A. (1999). Journal of the Royal Society of New Zealand 29: 245-255.
This paper describes the first major work we carried out on lakes as part of a new PGSF-funded research programme covering 1996-1998. It describes the major ion (Na, K, Mg, Ca, Sr, Cl, SO4-, alkalinity, reactive Si) and trace metal (Cu, Zn, Fe, Mn, Cd and Pb) compositions of Lakes Hayes and Manapouri. Both lakes were studied on five occasions throughout the seasonal cycle and depth range of each lake. In L. Manapouri, seasonal changes in both major element and trace metal compositions were negligible and almost within the precision of analytical methods, indicating a highly uniform water composition. Major element concentrations were extremely low by global standards, in most cases below the 1% percentile level for global fresh waters. By contrast, the much shallower L. Hayes exhibited much higher major element concentrations, close to the global mean. In addition, this lake showed a clear anoxic sub-surface layer during summer in which concentrations of the redox-active metals Fe and Mn became very high. Evidence of surface water utilisation of reactive Si, and deeper water scavenging of Cu, were both found in this lake.
Mercury Bioaccumulation in Rainbow Trout (Oncorhynchus Mykiss) and the Trout Food Web in Lakes Okareka, Okaro, Tarawera, Rotomahana and Rotorua, New Zealand. Kim, J.P. and Burggraaf, S. (1999). Water, Air and Soil Pollution 115: 535-546.
Methyl mercury (Hg) was determined in rainbow trout (Oncorhynchus mykiss) and organisms in the lower trophic levels: smelts (Retropinna retropinna), bullies (Gobiomorphus cotidianus), koura (Paranephrops planifrons); and zooplankton (Daphnia carinata and Calamoecia lucasi) in Lakes Okareka, Okaro, Tarawera, Rotorua and Rotomahana, New Zealand. Water concentrations of total Hg (HgT) and methyl Hg was also measured. Mean methyl Hg concentrations in the trout, the prey species (smelts, bullies and koura) and zooplankton increased linearly with mean HgT and methyl Hg chloride (CH3HgCl) concentrations in water. Most of the bio-magnification of methyl Hg occurred in the lower trophic levels of the trout food web (104.72) between the zooplankton and water. The bioaccumulation factors between the forage fish and zooplankton were 100.73 for bullies and 101.06 for smelt. Methyl Hg was 100.41 to 100.95 times greater in the trout then their prey.
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Methylmercury in Rainbow Trout (Oncorhynchus mykiss) from Lakes Okareka, Okaro, Rotomahana, Rotorua and Tarawera, North Island, New Zealand. Kim, J.P.(1995). Science of the Total Environment 164: 209-219.
Methylmercury (methyl Hg) was determined in muscle tissue of rainbow trout from five lakes in the North Island, New Zealand to examine the within-lake variation of methyl Hg with fish length and age, and the between-lake differences of methyl Hg in fish due to geothermal emanations. Methyl Hg in trout ranged from 0.07 to 4.13 µg g-1 for all the lakes studied. There were distinct variations of methyl Hg with length and age in each lake. Lakes strongly influenced by geothermal input had methyl Hg increases with length and age. Methyl Hg in the trout increased slightly, or not at all in lakes with low geothermal input. Variability methyl Hg in trout > 40 cm was observed in four lakes, which may be due to changes in trout diet. An analysis of covariance indicated there were different methyl Hg concentrations in trout from four lakes which varied with increased geothermal input. A principal components analysis of all the lakes yielded two major axes. The first was strongly correlated with geothermal input and the second with mean length. Therefore, geothermal emanations and fish size were important factors influencing methyl Hg in the trout.
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