Browsing by Author "Martin, R"

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    Early results from the ANSTO/NIWA 14C of atmospheric methane program
    (12th International Conference on Accelerator Mass Spectrometry (AMS-12), 2011-03-24) Smith, AM; Brailsford, G; Yang, B; Bromley, T; Martin, R
    development and proving of the laser heated microfurnace we have used it to prepare 45 samples of ~ 16 μg of carbon. These comprised CO2, derived from atmospheric methane, frozen back into glass breakseals following measurement for δ13C at NIWA. There were three sample sets: 15 from Baring Head, NZ (BHD), collected each ~ 15 days between March and September 2009, 9 from Arrival Heights, Antarctica (SCT), collected each ~ 41 days between February 2008 and January 2009, plus 21 samples taken along a Pacific Ocean voyage from Nelson (NZ) – Osaka (Japan) in December 2005 (FTW). All samples were measured to better than 1% precision, sufficient to reveal a 14CH4 signal. The BHD set shows significant temporal variation in 14C for baseline air passing over the Southern Ocean, whereas the SCT set shows a lesser variation for Antarctic air. The FTW set covers a S-N transect across the Pacific Ocean, showing the influence of the ITCZ (5°-10° N) and different meteorological conditions on the concentration, δ13C and Δ14C of CH4 and demonstrates that CH4 is not well mixed. Graphitisation reactions averaged 32 min with 0.7 mg of Fe, reduced from Fe2O3, as the catalyst. The samples, blanks and standards were measured in two 10 minute blocks; some were measured again to improve statistics. Average 13C4+ currents per microgram of carbon were 13, 4 and 2 nA/μg for each 10 min block. Similarly-sized targets prepared in the conventional furnace with Fe2O3 gave 8, 5 and 2 nA/μg for each 10 min block. Graphitisation efficiencies were typically 90-100% for microfurnace samples, compared with 37-84% for conventional furnace samples. Subsequent examination by microscope showed that the cesium beam was well-centred on the 1 mm diameter recess and that effectively all C/Fe was sputtered, leading to a (minimum) estimation of ~4% overall AMS measurement efficiency. Copyright (c) 2011 AMS12
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    NIWA’s δ13C-CO2 measurement programme: twenty years of monitoring in New Zealand and Antarctica, including the performance assessment of an in-situ analyser at Baring Head
    (American Geophysical Union, 2018-12-13) Moss, RC; Brailsford, GW; Martin, R; Nankivell, C; Nicol, S; Trans, PP; Mikaloff-Fletcher, SE; Michel, S; Keeling, RF; Werczynski, S; Gorjan, P; Sperlich, P
    NIWA is monitoring atmospheric trace gas species at multiple locations in New Zealand and Antarctica. NIWA’s main monitoring sites include i) Baring Head (BHD), a coastal site at the Southern tip of New Zealand’s North Island, ii) Lauder (LAU), an inland site in the central South Island of New Zealand and iii) Arrival Heights (ARH), an observatory on Ross Island in McMurdo Sound in Antarctica. Stable carbon isotopes in atmospheric carbon dioxide (δ13C-CO2) are measured at all three sites and represent a tracer to constrain CO2 fluxes. NIWA’s δ13C-CO2 measurements started in 1997 at BHD and ARH, while it commenced in 2009 at LAU. At all three sites, air is sampled in flasks during specific meteorological conditions, i.e. during Southerly events at BHD to sample Southern Ocean background air, or during mid-afternoon at LAU when the atmospheric boundary layer is well mixed. All flasks are analysed for δ13C-CO2 at the main gaslab in Wellington, using the same Gas Chromatography coupled Isotope Ratio Mass Spectrometry (GC-IRMS) system, ensuring optimal internal data consistency. Our instrument comprises a purpose-built GC unit and a commercial IRMS (MAT 252, Thermo Fisher, Bremen, Germany). In the last 20 years, the δ13C-CO2 monitoring programme has generated 1,708 measurements, with about 1182 from BHD, 158 from ARH, 368 from LAU. BHD is also sampled for δ13C-CO2 analysis within the NOAA and the Scripps flask networks, providing continuous intercomparison time series. In collaboration with the Australian Nuclear Science and Technology Organisation (ANSTO), we monitor Radon at BHD since 2015. Radon indicates if the sampled air has been in contact with terrestrial air masses, highlighting the potential for contamination with CO2 from terrestrial sources, which would impact on δ13C-CO2 observations. We also collaborate with Thermo Fisher (Bremen, Germany) and deployed Delta Ray – an in-situ analyser for δ13C and δ18O in atmospheric CO2 – at BHD. We compare the Delta Ray time series of δ13C and δ18O to δ13C-CO2 measurements in co-located flask samples as well as to continuous CO2 mole fractions, Radon and meteorological data from BHD.
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    Trace metal content in inhalable particulate matter (PM10 and PM2.5 collected from historical mine waste deposits using a laboratory-based approach
    (Springer, 2016-05-05) Martin, R; Dowling, K; Pearce, DC; Florentine, S; McKnight, S; Stelcer, E; Cohen, DD; Stopic, A; Bennett, JW
    Mine wastes and tailings are considered hazardous to human health because of their potential to generate large quantities of highly toxic emissions of particulate matter (PM). Human exposure to As and other trace metals in PM may occur via inhalation of airborne particulates or through ingestion of contaminated dust. This study describes a laboratory-based method for extracting PM2.5–10 (coarse) and PM2.5 (fine) particles from As-rich mine waste samples collected from an historical gold mining region in regional, Victoria, Australia. We also report on the trace metal and metalloid content of the coarse and fine fraction, with an emphasis on As as an element of potential concern. Laser diffraction analysis showed that the proportions of coarse and fine particles in the bulk samples ranged between 3.4–26.6 and 0.6–7.6 %, respectively. Arsenic concentrations were greater in the fine fraction (1680–26,100 mg kg−1) compared with the coarse fraction (1210–22,000 mg kg−1), and Co, Fe, Mn, Ni, Sb and Zn were found to be present in the fine fraction at levels around twice those occurring in the coarse. These results are of particular concern given that fine particles can accumulate in the human respiratory system. Our study demonstrates that mine wastes may be an important source of metal-enriched PM for mining communities.© 2016, Springer Science+Business Media Dordrecht.