Determination of trace labile copper in environmental waters by magnetic nanoparticle solid phase extraction and high-performance chelation ion chromatography.

Cobalt magnetic nanoparticles surface functionalised with iminodiacetic acid were evaluated as a nano-particulate solid phase extraction absorbent for copper ions (Cu(2+)) from environmental water samples. Using an external magnetic field, the collector nanoparticles could be separated from the aqueous phase, and adsorbed ions simply decomplexed using dilute HNO3. Effects of pH, buffer concentration, sample and sorbent volume, extraction equilibrium time, and interfering ion concentration on extraction efficiency were investigated. Optimal conditions were then applied to the extraction of Cu(2+) ions from natural water samples, prior to their quantitation using high-performance chelation ion chromatography. The limits of detection (LOD) of the combined extraction and chromatographic method were ~0.1 ng ml(-1), based upon a 100-fold preconcentration factor (chromatographic performance; LOD=9.2 ng ml(-1) Cu(2+)), analytical linear range from 20 to 5000 ng mL(-1), and relative standard deviations=4.9% (c=1000 ng ml(-1), n=7). Accuracy and precision of the combined approach was verified using a certified reference standard estuarine water sample (SLEW-2) and comparison of sample determinations with sector field inductively coupled plasma mass spectrometry. Recoveries from the addition of Cu(2+) to impacted estuarine and rain water samples were 103.5% and 108.5%, respectively. Coastal seawater samples, both with and without prior UV irradiation and dissolved organic matter removal were also investigated using the new methodology. The effect of DOM concentration on copper availability was demonstrated.

Sediment profile characterisation at contaminated and reference locations in the Windmill Islands, East Antarctica.

Sediment profiles for pH, Eh, 28 elements, water and organic content are presented here for human impacted and reference locations in the Windmill Islands, East Antarctica. Variations in element concentrations are observed with increasing depth, especially at Brown Bay where the impact of past human activities is most pronounced in the top 10 cm. Spatial differences were observed between sediment profiles at reference and impacted locations and were largely explained by Pb variability in the top 5 cm. Median element concentrations from surface, middle and bottom regions of the sediment profile were compared to composite sample medians (no depth stratigraphy) for 11 elements at O'Brien Bay (reference) and Brown Bay (impacted). Pronounced differences were observed for Brown Bay, particularly surface and middle sections, implying that composite samples dilute the near surface anthropogenic signal by mixing with deeper uncontaminated sediment.

Lead isotopic signatures in Antarctic marine sediment cores: a comparison between 1M HCl partial extraction and HF total digestion pre-treatments for discerning anthropogenic inputs.

Sensitive analytical techniques are typically required when dealing with samples from Antarctica as even low concentrations of contaminants can have detrimental environmental effects. Magnetic Sector ICP-MS is an ideal technique for environmental assessment as it offers high sensitivity, multi-element capability and the opportunity to determine isotope ratios. Here we consider the Pb isotope record of five marine sediment cores collected from three sites in the Windmill Islands area of East Antarctica: Brown Bay adjacent to the current Australian station Casey, Wilkes near the abandoned US/Australian Station and McGrady Cove lying midway between the two. Two sediment pre-treatment approaches were considered, namely partial extraction with 1M HCl and total dissolution involving HF. Lead isotope ratio measurements made following sediment partial extraction provided a more sensitive indication of Pb contamination than either Pb concentrations alone (irrespective of sample pre-treatment method) or isotope ratios made after HF digestion, offering greater opportunity for discrimination between impacted and natural/geogenic samples and sites. Over 90% of the easily extractable Pb from sediments near Casey was anthropogenic in origin, consisting of Pb from major Australian deposits. At Wilkes impact from discarded batteries with a unique isotopic signature was found to be a key source of Pb contamination to the marine environment with ~70-80% of Pb being anthropogenic in origin. The country and source of origin of these batteries remain unknown. Little evidence was found suggesting contamination at Wilkes by Pb originating from the major US source, Missouri. No definitive assessment could be made regarding Pb impact at McGrady Cove as the collected sediment core was of insufficient depth. Although Pb isotope ratio signatures may indicate anthropogenic input, spatial concentration gradients at nearby Brown Bay suggest contamination at McGrady Cove is unlikely. We recommend Pb isotopic analysis following 1M HCl partial extraction pre-treatment as a powerful and sensitive method for tracing Pb contamination in marine sediments.

Multiple Pb sources in marine sediments near the Australian Antarctic Station, Casey.

An extensive Pb isotope ratio survey of approximately 100 marine sediment samples from near Casey Station, East Antarctica has been undertaken. Sediment surface grabs and cores were collected over nine years between 1997-2006 and, following HF total digestion, were analysed by magnetic sector ICP-MS. Fifty-two reference samples ([Pb] range 5-26 mg kg(-1)) from 6 non-impacted locations displayed a broad range of Pb isotope ratios representative of the natural background geology of the region ((208)Pb/(204)Pb ratios of 37.5-40; (206)Pb/(204)Pb ratios of 17-19). Potentially impacted sediments from Brown Bay (n=27, [Pb] range 18-215 mg kg(-1)), adjacent to the current and former Australian Stations at Casey (and the associated Thala Valley tip site) showed contamination by Pb characteristic of Broken Hill and Mt Isa Australian deposits ((208)Pb/(204)Pb and (206)Pb/(204)Pb values of 35.5-36 and 16.0-16.1, respectively). The nearby abandoned Wilkes Station was previously manned by both US (1957-59) and Australian (1959-69) expeditioners. Adjacent marine sediment samples (n=24, [Pb] range 13-40 mg kg(-1)) displayed Pb isotopic signatures suggesting anthropogenic input from multiple sources. On a three-isotope diagram Wilkes sediments were found to display Pb ratios lying intermediate between Missouri (US), Broken Hill/Mt Isa (Australia)/Idaho (US), and natural geogenic Pb end members. Discarded Pb batteries, paint samples and fuel spills were all considered in this work as possible point sources of Pb contamination to the local environment. Batteries are thought to be the dominant source.

Selenium status in Southern Tasmania.

OBJECTIVE: To assess the selenium status of Southern Tasmanians. DESIGN: Cross-sectional. SETTINGS: One thousand and five hundred adults randomly selected from the electoral roll living in the Greater Hobart region of Southern Tasmania, Australia, were invited to participate. SUBJECTS: The overall response rate was 22% (335/1500). INTERVENTIONS: A venous blood sample was collected and a questionnaire administered (consisting of brief demographic details and health questions) to subjects who granted informed consent. A previously validated assay using magnetic sector ICP-MS was employed for plasma analysis. RESULTS: Total plasma selenium levels for this sample population were normally distributed with a mean level of 110 microg/l (range 67-268 microg/l) indicating that the majority of the subjects were not selenium-depleted (71% with levels greater than 100 microg/l). Adjustment for differential age/gender response rates produced similar values. More women under 50 (42%) and men over 50 (32%) had selenium levels <100 microg/l with the potential for sub-optimal selenoprotein activity. Low education attainment was associated with low total selenium level (P<0.02). CONCLUSIONS: The majority of participants were not deficient in selenium. Given the narrow therapeutic window of supplementation, dietary advice to increase foods rich in selenium, particularly to higher risk groups, may be an effective means of increasing plasma selenium toward target levels.

The application of ICP-SMS, GF-AAS and HG-AFS to the analysis of water and sediment samples from a temperate stratified estuary.

Three atomic spectrometry techniques, namely sector field inductively coupled plasma mass spectroscopy, graphite furnace atomic absorption spectrometry and hydride generation atomic fluorescence spectroscopy (ICP-SMS, GF-AAS and HG-AFS, respectively), housed at separate independent laboratories, were used to analyse water and sediment samples collected from the Huon River Estuary, SE Tasmania (Australia) in the Austral spring 1998. A dithiocarbamate-chelation/back-extraction technique was used to separate and preconcentrate Co, Ni, Cu, Zn, Cd and Pb from eight collected water samples prior to analysis by ICP-SMS and GF-AAS. A number of other elements in the waters were analysed directly (Mn, Fe and Zn by GF-AAS; As by HG-AFS), or following sample dilution (1 + 19: V, Mn, Fe, As, Mo, Ba and U by ICP-SMS). Where possible, previously corroborated GF-AAS and HG-AFS techniques were used to verify obtained ICP-SMS results. From the analysis of four reference waters (SLEW-1 and -2, SLRS-3 and NASS-5), good agreement, to within +/- 10-20%, was typically found between certified (or information only values) and measured results (irrespective of analytical technique). Exceptions included Zn (and sometimes Fe) that could not be quantified by ICP-SMS due to elevated blank signals, and As which was found to lie below ICP-SMS detection limits. For Huon Estuary water samples, inter-method agreement was within +/- 10-20% (for those elements amenable to analysis by more than one technique). Nitric acid extracts of two certified reference materials (Buffalo River Sediment and BCSS-1) and six Huon Estuary sediments were analysed by ICP-SMS (for Al, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb) and HG-AFS (for As). Results from the certified reference materials indicated extraction efficiencies of 60 70% (for most elements). A close correlation between ICP-SMS and HG-AFS was obtained for leachable As in the sediments. In terms of potential inorganic contaminants, the Huon Estuary was found to be a relatively 'clean' water system. The elemental concentrations measured in water and sediment samples from this region were found to lie within current Australian guidelines for estuaries. In general, no one analytical technique was able to accurately determine all elements in all samples from this relatively pristine estuarine environment. A combination of all three analytical techniques was necessary for the successful analysis of the elements considered in this study.

Enhanced sensitivity for Os isotope ratios by magnetic sector ICP-MS with a capacitive decoupling Pt guard electrode.

A magnetic sector ICP-MS with enhanced sensitivity was used to measure Os isotope ratios in solutions of low Os concentration (approximately 1 ng g(-1) or less). Ratios with 192Os as the basis were determined, while the geologically useful 187Os/188Os ratio was also measured. Sample introduction was via the traditional nebuliser-spray chamber method. A capacitive decoupling Pt shield torch was developed "in-house" and was found to increase Os signals by approximately 5 x under "moderate" plasma conditions (1050 W) over that found during normal operation (1250 W). Sensitivity using the guard electrode for 192Os was approximately 250-350,000 counts s(-1) per ng g(-1) Os. For a I ng g(-1) Os solution with no guard electrode, precisions of the order of 0.2-0.3% (189Os/192Os and 190Os/192Os) to approximately 1% or greater (186Os/192Os, 187Os/192Os and 187Os/188Os) were found (values as 1 sigma for n = 10). With the guard electrode in use, ratio precisions were found to improve to 0.2 to 0.8%. The total amount of Os used in the acquisition of this data was approximately 2.5 ng per measurement per replicate. At the higher concentration of 10 ng g(-1), precisions of the order of 0.15-0.3% were measured (for all ratios), irrespective of whether the shield torch was used. Ratio accuracy was confirmed by comparison with independently obtained NTIMS data. For both Os concentrations considered, the improvement in precision offered by the guard electrode (if any) was small in comparison to calculated theoretical values based on Poisson counting statistics, suggesting noise contributions from other sources (such as the sample introduction system, plasma flicker etc). At lower Os concentrations (to 100 pg g(-1)) no appreciable loss of ratio accuracy was observed, although as expected based on counting statistics, poorer precisions of the order of 0.45-3% (1 sigma, n = 5) were noted. Re was found to have a detrimental effect on the precision of Os ratios involving 187Os, indicating that separation of Re and Os samples is a necessary pre-requisite for highly accurate and precise Os isotope ratio measurements.

Effect of diisopropylfluorophosphate on muscarinic and gamma-aminobutyric acid receptors in visual cortex of cats.

Administration of diisopropylfluorophosphate (DFP), an organophosphorus (OP) compound, irreversibly inhibits acetylcholinesterase (AChE) and results in cholinergic hyperactivity. This study investigated muscarinic and gamma-aminobutyric acid (GABA) receptor changes in visual cortex of cats following an acute exposure to DFP. A single acute administration of DFP (4 mg/kg) decreased the number of muscarinic receptors at 2, 10, and 20 hours after treatment. GABA receptors were elevated at 2 and 10 hours but returned to within control levels at 20 hours. No significant alteration in muscarinic or GABA receptor affinity was noted. In all cases cortical AChE activity was inhibited 60-90%. These findings show a down regulation of muscarinic receptors after DFP associated with low AChE activity. GABA receptors also are altered, and may be part of a compensatory mechanism to counteract excess cholinergic stimulation.