Jonathan P. Kim

Mercury Bioaccumulation in Rainbow Trout (Oncorhynchus mykiss) and the Trout Food Web in Lakes Okareka, Okaro, Tarawera, Rotomahana and Rotorua, New Zealand

Methyl mercury (Hg) was determined in rainbow trout (Oncorhynchus mykiss) and organisms in the lower tropic 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 were 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.

Effect of UVB Irradiation on Cu2+-Binding Organic Ligands and Cu2+ Speciation in Alpine Lake Waters of New Zealand

Environmental Context. The bioavailability of dissolved metals in natural waters is directly affected by metal-sequestering agents. These agents include soil-derived matter and compounds released by microorganisms, since copper can support or inhibit aquatic microorganisms depending on concentration. During summer the levels of copper increase in surface waters, an effect intuitively attributable to increased ultraviolet light degrading the sequestering agents more effectively, leading to a concurrent release of the metal. This paper shows that the amount of degradation attributable to light is too low to explain the metal release and that a biological influence may instead be responsible. Abstract. The influence of UVB irradiation on the Cu2+ binding by natural organic ligands in six alpine lakes on the South Island, New Zealand, has been investigated using competitive ligand equilibration with salicylaldoxime and detection by cathodic stripping voltammetry (CLE-CSV). During austral summer 2002–2003 the total dissolved Cu ([Cu]T), the concentration of strong Cu2+-binding ligands ([L]T), and their conditional stability constant K´´ were determined in surface samples of all six lakes. All lakes exhibited appreciable concentrations of a strong Cu2+ binding ligand with similar K´´ values and concentrations always exceeding [CuT], thus dominating Cu2+ speciation. Four lakes (Hayes, Manapouri, Wanaka, Te Anau) showed no appreciable trend in [LT] throughout the summer, whereas in Lakes Wakatipu and Hawea [LT] increased steadily throughout this period. Laboratory UVB irradiation of lake water samples using a 400 W mercury lamp with a Pyrex glass filter (λ > 280 nm) showed that Cu2+-binding ligands are destroyed by UVB radiation, causing [L]T to decrease with a rate of –0.588 nmol L–1 h–1 (r2 0.88). From this we calculate that the in situ ligand destruction rate by UVB in summer for surface waters of these lakes is too small to significantly affect [LT], and conclude that variations in ligand concentrations must result from seasonally variable biological factors.

Determination of labile Cu2+ in fresh waters by chemiluminescence: interference by iron and other cations

Analysis of labile Cu(2+) in fresh waters using the Cu(2+)-catalysed oxidation of 1,10-phenanthroline by superoxide anion radical has been investigated. It was found that certain metal ions, notably Fe(3+), Fe(2+) and Pb(2+) enhance the chemiluminescence (CL) intensity of this reaction by up to an order of magnitude when present in the muM concentration range. This enhancement is considered to arise through coordination of the metal ion to 1,10-phenanthroline, which prevents free rotation of the benzene rings in the excited state intermediate thought to be responsible for light emission. This introduces a potential interference when analyzing fresh waters, which usually contain Fe(3+) concentrations of this magnitude. However, the enhancement effect saturates at about 4muM Fe(3+), so that reliable results can be obtained if the water sample is supplemented with Fe(3+) to reach this level. Application of the enhanced technique to a river water, and a reservoir to which CuSO(4) had been added to control algal growth, are described. In both cases, only a small fraction of total dissolved Cu(2+) is labile with respect to the chemiluminesence method.

Methyl mercury bioaccumulation in long-finned eels, Anguilla dieffenbachii, from three rivers in Otago, New Zealand

This research focuses on mercury (Hg) bioaccumulation in New Zealand long-tinned eels (Anguilla dieffenbachii) from the aquatic environment. Total Hg (HgT) and methyl mercury (MeHg) concentrations were determined in muscle tissue from eels living in three South Island rivers dominated respectively by urban, native bush and agricultural land-uses. Most of the Hg in eels was MeHg (> 84%) and the MeHg concentrations increased linearly with both length and eel age for a given river habitat. The annual growth rates for eels from the urban and agricultural streams were greater than for eels from the native bush stream. The average MeHg accumulation rate was significantly higher for the eels in the agricultural stream compared with either the urban or native bush catchments. These results are probably due to a combination of factors and further investigations in the lower food web are necessary to elucidate the exact mechanisms of MeHg bioaccumulation in these creatures.

Zinc speciation in Lakes Manapouri and Hayes, New Zealand

A 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. In 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 0.46 nM. Conditional stability constants (log K) for the complexation of zinc to these ligands were high,with values ranging between 10.0 and 11.1. Calculated free Zn 2+ concentrations for both lakes were in the low picomolar range (5—48 pM). Such low free Zn 2+ levels may limit the growth of some phytoplankton in both lakes.

Trace metal and major ion concentrations in Lakes Hayes and Manapouri

The major ion (Na+, K+, Mg2+, Ca2+, Sr∗, Cl, SO4 2, alkalinity, reactive Si) and trace metal (Cu, Zn, Fe, Mn, Cd and Pb) compositions of Lakes Hayes and Manapoun have been studied on five occasions throughout the seasonal cycle and depth range of each lake In L Manapoun, seasonal changes in both major element and trace metal concentrations 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

Non-destructive assessment of polycyclic aromatic hydrocarbon (PAH) exposure by fluorimetric analysis of crab urine

The detection of urinary polycyclic aromatic hydrocarbon (PAH) metabolites by fluorescence spectrophotometry is particularly effective as a practical means to assess PAH exposure in decapod crabs. However, the practical application of this technique has thus far only been tested for the European shore crab (Carcinus maenas) and only a few field studies have been conducted in heavily polluted areas. The present study evaluated the adaptability of this method as a rapid, cost-effective and non-destructive biomonitoring tool for the New Zealand crab species, Macrophthalmus hirtipes (stalk-eyed mud crab). A field gradient could be detected among the sites and different input sources of PAH contamination could be discerned through the differentiation of pyrogenic and petrogenic PAH signatures. The present study shows that the fluorescence screening method is sensitive to relatively low levels of PAH contamination and more broadly applicable to smaller crab species than C. maenas, for which the technique was developed.

Size-Distribution Analysis of Sub-Micron Colloidal Particles in River Water

The particle size spectra of sub-micron colloidal particles collected from a river water, the Water of Leith in Dunedin, New Zealand, have been determined by transmission electron microscopy (TEM). Particles were isolated onto hydrophilic carbon films by ultracentrifugation at 300,000 g for 1 hr. Size spectra were found to conform to a power-law size distribution dn/dr = A r − s, behaviour also found for much larger-sized particles in natural waters and marine colloids. Values of the exponent s for unfiltered samples were in the range 2.3–2.9, consistent with Brownian aggregation as the principal mechanism maintaining the size spectrum. Comparison with spectra obtained from sampled prefiltered through Nuclepore 0.4µm filters showed clear evidence of particle removal down to 100–120 nm radius by filtration. Particles exhibited a range of electron densities under TEM, indicating a mixture of inorganic minerals and organic matter in the colloidal size range. Examples of fractal aggregates were also found.

Processes affecting the chemical composition of Blue Lake, an alluvial gold-mine pit lake in New Zealand

Blue Lake is an abandoned, water-filled alluvial gold-mine pit in Central Otago, New Zealand. Alluvial gold mining is generally considered to be chemically benign, unless mercury is added to assist gold separation. The major element, trace metal and isotopic composition of the pit lake was compared to nearby, unaffected streams. Blue Lake was found to be enriched in the major cations, with levels that were 2–5 times higher than in unaffected streams. Furthermore, Cu, Ni and Zn concentrations exceeded 10 nmol L–1 in Blue Lake; these levels were 2–30 times higher than those in nearby, unaffected streams. Processes affecting the lake’s characteristics include evaporative concentration, and the oxidation and dissolution of locally derived sulfide and sulfate minerals. Localised acidification in surface and ground waters around the lake leads to the mobilisation of Zn and Ni, resulting in lake waters being strongly enriched in these trace metals (concentrations greater than 40 nmol L–1), whereas surrounding stream waters have much lower Ni and Zn concentrations (less than 5 nmol L–1). Ongoing evaporative concentration, and the continuing mobilisation of trace metals, implies that metal enrichment in lake waters will continue to occur. The present study demonstrated that the ‘benign’ process of alluvial gold mining can have significant chemical consequences in resulting water bodies.

Geochemical cycling of major and minor elements in the Taieri River and Waipori River catchments

The concentrations of the major ions (Na+, K+, Ca2+, Mg2+, Cl, SO4 2, total alkalinity AT and dissolved silica SiO2) and the dissolved trace metals Cu and Zn have been determined in the combined catchments of the Waipori and Taieri Riveis, in Otago, New Zealand In general, the concentrations of the major ions were low, and were similar to levels observed in other uncontaminated rivers in the South Island However elevated concentrations of Na+, Cl, Ca2+, HCO,, with mole ratios characteristic of seawater, were found in the lower catchment, indicating intrusion of sea salts by tidal mixing Significant inputs of nutrients, Zn, and, to a lesser extent, Cu, resulting from sewage effluent of the Mosgiel treatment plant, were observed at some periods during a time series of samples collected over a 20‐month period Estimates, based on the data, of the annual flux of nutrients and trace metals to the lower Taieri River catchment from this source indicate that the treatment plant contributes approximately 45% of the nutrients NO3, PO4 3, and dissolved Zn This implies that the recent closure of this treatment plant should result in a significant improvement in the water quality of the lower Taieri River