Publications by authors named "Niels C Munksgaard"

17 Publications

  • Page 1 of 1

Impact of an extreme monsoon on CO and CH fluxes from mangrove soils of the Ayeyarwady Delta, Myanmar.

Sci Total Environ 2021 Mar 4;760:143422. Epub 2020 Nov 4.

School of Biological Sciences, The University of Queensland, St Lucia, QLD 4067, Australia.

Mangrove ecosystems can be both significant sources and sinks of greenhouse gases (GHGs). Understanding variability in flux and the key factors controlling emissions in these ecosystems are therefore important in the context of accounting for GHG emissions. The current study is the first to quantify GHG emissions using static chamber measurements from soils in disused aquaculture ponds, planted mangroves, and mature mangroves from the Ayeyarwady Delta, Myanmar. Soil properties, biomass and estimated net primary productivity were also assessed. Field assessments were conducted at the same sites during the middle of the dry season in February and end of the wet season in October 2019. Rates of soil CO efflux were among the highest yet recorded from mangrove ecosystems, with CO efflux from the 8 year old site reaching 86.8 ± 17 Mg CO ha yr during February, an average of 862% more than all other sites assessed during this period. In October, all sites had significant rates of soil CO efflux, with rates ranging from 31.9 ± 4.4 Mg CO ha yr in a disused pond to 118.9 ± 24.3 Mg CO ha yr in the 8 year old site. High soil CO efflux from the 8 year old site in February is most likely attributable to high rates of primary production and belowground carbon allocation. Elevated CO efflux from all sites during October was likely associated with the extreme 2019 South Asian monsoon season which lowered soil pore salinity and deposited new alluvium, stimulating both autotrophic and heterotrophic activity. Methane efflux increased significantly (50-400%) during the wet season from all sites with mangrove cover, although was a small overall component of soil GHG effluxes during both measurement periods. Our results highlight the critical importance of assessing GHG flux in-situ in order to quantify variability in carbon dynamics over time.
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http://dx.doi.org/10.1016/j.scitotenv.2020.143422DOI Listing
March 2021

Land transformation in tropical savannas preferentially decomposes newly added biomass, whether C or C derived.

Ecol Appl 2020 12 28;30(8):e02192. Epub 2020 Jul 28.

Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, North Territory, Australia.

As tropical savannas are undergoing rapid conversion to other land uses, native C -C vegetation mixtures are often transformed to C - or C -dominant systems, resulting in poorly understood changes to the soil carbon (C) cycle. Conventional models of the soil C cycle are based on assumptions that more labile components of the heterogenous soil organic C (SOC) pool decompose at faster rates. Meanwhile, previous work has suggested that the C -derived component of SOC is more labile than C -derived SOC. Here we report on long-term (18 months) soil incubations from native and transformed tropical savannas of northern Australia. We test the hypothesis that, regardless of the type of land conversion, the C component of SOC will be preferentially decomposed. We measured changes in the SOC and pyrogenic carbon (PyC) pools, as well as the carbon isotope composition of SOC, PyC and respired CO , from 63 soil cores collected intact from different land use change scenarios. Our results show that land use change had no consistent effect on the size of the SOC pool, but strong effects on SOC decomposition rates, with slower decomposition rates at C -invaded sites. While we confirm that native savanna soils preferentially decomposed C -derived SOC, we also show that transformed savanna soils preferentially decomposed the newly added pool of labile SOC, regardless of whether it was C -derived (grass) or C -derived (forestry) biomass. Furthermore, we provide evidence that in these fire-prone landscapes, the nature of the PyC pool can shed light on past vegetation composition: while the PyC pool in C -dominant sites was mainly derived from C biomass, PyC in C3-dominant sites and native savannas was mainly derived from C biomass. We develop a framework to systematically assess the effects of recent land use change vs. prior vegetation composition.
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http://dx.doi.org/10.1002/eap.2192DOI Listing
December 2020

Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica.

Proc Natl Acad Sci U S A 2020 02 11;117(8):3996-4006. Epub 2020 Feb 11.

Department of Earth Sciences, Royal Holloway University of London, Surrey TW20 OEX, United Kingdom.

The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice-climate feedbacks that further amplify warming.
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http://dx.doi.org/10.1073/pnas.1902469117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7049167PMC
February 2020

Data Descriptor: Daily observations of stable isotope ratios of rainfall in the tropics.

Sci Rep 2019 10 8;9(1):14419. Epub 2019 Oct 8.

College of Science and Engineering, James Cook University, Cairns, Australia.

We present precipitation isotope data (δH and δO values) from 19 stations across the tropics collected from 2012 to 2017 under the Coordinated Research Project F31004 sponsored by the International Atomic Energy Agency. Rainfall samples were collected daily and analysed for stable isotopic ratios of oxygen and hydrogen by participating laboratories following a common analytical framework. We also calculated daily mean stratiform rainfall area fractions around each station over an area of 5° x 5° longitude/latitude based on TRMM/GPM satellite data. Isotope time series, along with information on rainfall amount and stratiform/convective proportions provide a valuable tool for rainfall characterisation and to improve the ability of isotope-enabled Global Circulation Models to predict variability and availability of inputs to fresh water resources across the tropics.
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http://dx.doi.org/10.1038/s41598-019-50973-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6783450PMC
October 2019

A global database of water vapor isotopes measured with high temporal resolution infrared laser spectroscopy.

Sci Data 2019 01 22;6:180302. Epub 2019 Jan 22.

Institute of Industrial Science, The University of Tokyo, Komaba, Tokyo, Japan.

The isotopic composition of water vapour provides integrated perspectives on the hydrological histories of air masses and has been widely used for tracing physical processes in hydrological and climatic studies. Over the last two decades, the infrared laser spectroscopy technique has been used to measure the isotopic composition of water vapour near the Earth's surface. Here, we have assembled a global database of high temporal resolution stable water vapour isotope ratios (δO and δD) observed using this measurement technique. As of March 2018, the database includes data collected at 35 sites in 15 Köppen climate zones from the years 2004 to 2017. The key variables in each dataset are hourly values of δO and δD in atmospheric water vapour. To support interpretation of the isotopologue data, synchronized time series of standard meteorological variables from in situ observations and ERA5 reanalyses are also provided. This database is intended to serve as a centralized platform allowing researchers to share their vapour isotope datasets, thus facilitating investigations that transcend disciplinary and geographic boundaries.
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http://dx.doi.org/10.1038/sdata.2018.302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6343514PMC
January 2019

Hydroperiod, soil moisture and bioturbation are critical drivers of greenhouse gas fluxes and vary as a function of landuse change in mangroves of Sulawesi, Indonesia.

Sci Total Environ 2019 Mar 10;654:365-377. Epub 2018 Nov 10.

Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia.

The loss and degradation of mangroves can result in potentially significant sources of atmospheric greenhouse gas (GHG) emissions. For mangrove rehabilitation carbon projects, quantifying GHG emissions as forests regenerate is a key accounting requirement. The current study is one of the first attempts to systematically quantify emissions of carbon dioxide (CO), nitrous oxide (NO) and methane (CH) from: 1) aquaculture ponds, 2) rehabilitating mangroves, and 3) intact mangrove sites and frame GHG flux within the context of landuse change. In-situ static chamber measurements were made at three contrasting locations in Sulawesi, Indonesia. The influence of key biophysical variables known to affect GHG flux was also assessed. Peak GHG flux was observed at rehabilitating (32.8 ± 2.1 Mg COe ha y) and intact, mature reference sites (43.8 ± 4.5 Mg COe ha y) and a dry, exposed disused aquaculture pond (30.6 ± 1.9 Mg COe ha y). Emissions were negligible at low productivity rehabilitating sites with high hydroperiod (mean 1.0 ± 0.1 Mg COe ha y) and an impounded, operational aquaculture pond (1.1 ± 0.2 Mg COe ha y). Heterogeneity in biophysical conditions and geomorphic position exerted a strong influence on GHG flux, with the longer hydroperiod and higher soil moisture content of seaward fringing mangroves correlated with decreased fluxes. A greater abundance of Mud lobster mounds and root structures in landward mangroves correlated to higher flux. When viewed across a landuse change continuum, our results suggest that the initial conversion of mangroves to aquaculture ponds releases extremely high rates of GHGs. Furthermore, the re-institution of hydrological regimes in dry, disused aquaculture ponds to facilitate tidal flushing is instrumental in rapidly mediating GHG flux, leading to a significant reduction in baseline emissions. This is an important consideration for forest carbon project proponents seeking to maximise creditable GHG emissions reductions and removals.
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http://dx.doi.org/10.1016/j.scitotenv.2018.11.092DOI Listing
March 2019

Automated calibration of laser spectrometer measurements of δ O and δ H values in water vapour using a Dew Point Generator.

Rapid Commun Mass Spectrom 2018 Jun;32(12):1008-1014

College of Science and Engineering and Centre for Tropical Environmental and Sustainability Science, James Cook University, Cairns, Australia.

Rationale: Continuous measurement of stable O and H isotope compositions in water vapour requires automated calibration for remote field deployments. We developed a new low-cost device for calibration of both water vapour mole fraction and isotope composition.

Methods: We coupled a commercially available dew point generator (DPG) to a laser spectrometer and developed hardware for water and air handling along with software for automated operation and data processing. We characterised isotopic fractionation in the DPG, conducted a field test and assessed the influence of critical parameters on the performance of the device.

Results: An analysis time of 1 hour was sufficient to achieve memory-free analysis of two water vapour standards and the δ O and δ H values were found to be independent of water vapour concentration over a range of ≈20,000-33,000 ppm. The reproducibility of the standard vapours over a 10-day period was better than 0.14 ‰ and 0.75 ‰ for δ O and δ H values, respectively (1 σ, n = 11) prior to drift correction and calibration. The analytical accuracy was confirmed by the analysis of a third independent vapour standard. The DPG distillation process requires that isotope calibration takes account of DPG temperature, analysis time, injected water volume and air flow rate.

Conclusions: The automated calibration system provides high accuracy and precision and is a robust, cost-effective option for long-term field measurements of water vapour isotopes. The necessary modifications to the DPG are minor and easily reversible.
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http://dx.doi.org/10.1002/rcm.8131DOI Listing
June 2018

Cadmium uptake and zinc-cadmium antagonism in Australian tropical rock oysters: Potential solutions for oyster aquaculture enterprises.

Mar Pollut Bull 2017 Oct 19;123(1-2):47-56. Epub 2017 Sep 19.

Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia.

Variable and occasionally high concentrations of cadmium in wild oysters at a remote location with the potential to develop aquaculture enterprises motivated research into the distribution and sources of metals in oysters, seawater, sediment, suspended solids and phytoplankton. Saccostrea mytiloides and Saccostrea mordax contained cadmium concentrations exceeding the food standard maximum level (ML) at three of four sites. At one site with high zinc levels in sediment, oyster cadmium levels were below the ML. Metal levels in seawater were not correlated with cadmium levels in oysters but high cadmium/zinc ratios were measured in Trichodesmium erythraeum blooms. We suggest that oysters accumulate cadmium mainly from annual phytoplankton blooms except at sites where zinc availability is sufficiently high to prevent uptake though a mechanism of antagonistic exclusion. Knowledge of the source and uptake mechanisms of cadmium in oysters should lead to new management strategies to reduce cadmium levels in farmed oysters.
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http://dx.doi.org/10.1016/j.marpolbul.2017.09.031DOI Listing
October 2017

Enrichment of N/N in wastewater-derived effluent varies with operational performance of treatment systems: implications for isotope monitoring in receiving environments.

Environ Monit Assess 2017 Jan 24;189(1):36. Epub 2016 Dec 24.

Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, NT, 0810, Australia.

Stable nitrogen isotope ratios are routinely used to trace the dispersion and assimilation of wastewater-derived N in receiving environments, but few isotope studies have investigated wastewater treatment plants and ponds themselves. An improved understanding of N isotope compositions in effluent will help assess treatment plant processes and performance and will help trace sources of excess nutrients in receiving environments. Here, we assess N budgets and treatment processes in seven wastewater treatment plants and wastewater stabilisation ponds in northern Australia based on concentrations and isotope ratios of N in effluent. We show that δN values in effluent are linked to treatment type, effectiveness of conversion of ammonia and levels of gaseous N emissions. These relationships suggest that N isotope monitoring of wastewater treatment plants and ponds can provide an integrated assessment of treatment performance and gaseous N emissions on a pond- or plant-wide scale that is not readily available through other methods. Our findings further imply that monitoring N isotope ratios in receiving environments cannot be assumed to be universally effective as their sensitivity to uptake of wastewater-derived N will vary with the characteristics of individual treatment systems. Paradoxically, N isotope monitoring is less effective where treatment systems are functioning poorly and where monitoring needs are the greatest.
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http://dx.doi.org/10.1007/s10661-016-5754-9DOI Listing
January 2017

Stable isotopes in leaf water of terrestrial plants.

Plant Cell Environ 2016 May 23;39(5):1087-102. Epub 2016 Mar 23.

Research School of Biology, The Australian National University, Canberra, Australia.

Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water.
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http://dx.doi.org/10.1111/pce.12703DOI Listing
May 2016

Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014.

PLoS One 2015 5;10(3):e0119728. Epub 2015 Mar 5.

Centre for Tropical Environmental and Sustainability Science, College of Science, Technology and Engineering, James Cook University, Cairns, Queensland, Australia.

The isotope signatures registered in speleothems during tropical cyclones (TC) provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119728PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351091PMC
January 2016

Microwave extraction-isotope ratio infrared spectroscopy (ME-IRIS): a novel technique for rapid extraction and in-line analysis of δ18O and δ2H values of water in plants, soils and insects.

Rapid Commun Mass Spectrom 2014 Oct;28(20):2151-61

Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia; School of Earth and Environmental Sciences and Centre for Tropical Environmental and Sustainability Science, James Cook University, Cairns, Australia.

Rationale: Traditionally, stable isotope analysis of plant and soil water has been a technically challenging, labour-intensive and time-consuming process. Here we describe a rapid single-step technique which combines Microwave Extraction with Isotope Ratio Infrared Spectroscopy (ME-IRIS).

Methods: Plant, soil and insect water is extracted into a dry air stream by microwave irradiation within a sealed vessel. The water vapor thus produced is carried to a cooled condensation chamber, which controls the water vapor concentration and flow rate to the spectrometer. Integration of the isotope signals over the whole analytical cycle provides quantitative δ(18)O and δ(2) H values for the initial liquid water contained in the sample. Calibration is carried out by the analysis of water standards using the same apparatus. Analysis of leaf and soil water by cryogenic vacuum distillation and IRMS was used to validate the ME-IRIS data.

Results: Comparison with data obtained by cryogenic distillation and IRMS shows that the new technique provides accurate water isotope data for leaves from a range of field-grown tropical plant species. However, two exotic nursery plants were found to suffer from spectral interferences from co-extracted organic compounds. The precision for extracted leaf, stem, soil and insect water was typically better than ±0.3 ‰ for δ(18)O and ±2 ‰ for δ(2) H values, and better than ±0.1 ‰ for δ(18)O and ±1 ‰ for δ(2) H values when analyzing water standards. The effects of sample size, microwave power and duration and sample-to-sample memory on isotope values were assessed.

Conclusions: ME-IRIS provides rapid and low-cost extraction and analysis of δ(18)O and δ(2) H values in plant, soil and insect water (≈10-15 min for samples yielding ≈ 0.3 mL of water). The technique can accommodate whole leaves of many plant species.
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http://dx.doi.org/10.1002/rcm.7005DOI Listing
October 2014

Field-based cavity ring-down spectrometry of δ¹³C in soil-respired CO₂.

Isotopes Environ Health Stud 2013 Jun 16;49(2):232-42. Epub 2013 Jan 16.

Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia.

Measurement of soil-respired CO₂ at high temporal resolution and sample density is necessary to accurately identify sources and quantify effluxes of soil-respired CO₂. A portable sampling device for the analysis of δ(13)C values in the field is described herein. CO₂ accumulated in a soil chamber was batch sampled sequentially in four gas bags and analysed by Wavelength-Scanned Cavity Ring-down Spectrometry (WS-CRDS). A Keeling plot (1/[CO₂] versus δ(13)C) was used to derive δ(13)C values of soil-respired CO₂. Calibration to the δ(13)C Vienna Peedee Belemnite scale was by analysis of cylinder CO₂ and CO₂ derived from dissolved carbonate standards. The performance of gas-bag analysis was compared to continuous analysis where the WS-CRDS analyser was connected directly to the soil chamber. Although there are inherent difficulties in obtaining absolute accuracy data for δ(13)C values in soil-respired CO₂, the similarity of δ(13)C values obtained for the same test soil with different analytical configurations indicated that an acceptable accuracy of the δ(13)C data were obtained by the WS-CRDS techniques presented here. Field testing of a variety of tropical soil/vegetation types, using the batch sampling technique yielded δ(13)C values for soil-respired CO₂ related to the dominance of either C₃ (tree, δ(13)C=-27.8 to-31.9 ‰) or C₄ (tropical grass, δ(13)C=-9.8 to-13.6 ‰) photosynthetic pathways in vegetation at the sampling sites. Standard errors of the Keeling plot intercept δ(13)C values of soil-respired CO₂ were typically<0.4 ‰ for analysis of soils with high CO₂ efflux (>7-9 μmol m(-2) s(-1)).
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http://dx.doi.org/10.1080/10256016.2013.750606DOI Listing
June 2013

Continuous analysis of δ¹⁸O and δD values of water by diffusion sampling cavity ring-down spectrometry: a novel sampling device for unattended field monitoring of precipitation, ground and surface waters.

Rapid Commun Mass Spectrom 2011 Dec;25(24):3706-12

James Cook University, Earth and Environmental Sciences, Cairns, Queensland, Australia.

A novel sampling device suitable for continuous, unattended field monitoring of rapid isotopic changes in environmental waters is described. The device utilises diffusion through porous PTFE tubing to deliver water vapour continuously from a liquid water source for analysis of δ¹⁸O and δD values by Cavity Ring-Down Spectrometry (CRDS). Separation of the analysed water vapour from non-volatile dissolved and particulate contaminants in the liquid sample minimises spectral interferences associated with CRDS analyses of many aqueous samples. Comparison of isotopic data for a range of water samples analysed by Diffusion Sampling-CRDS (DS-CRDS) and Isotope Ratio Mass Spectrometry (IRMS) shows significant linear correlations between the two methods allowing for accurate standardisation of DS-CRDS data. The internal precision for an integration period of 3 min (standard deviation (SD) = 0.1‰ and 0.3‰ for δ¹⁸O and δD values, respectively) is similar to analysis of water by CRDS using an autosampler to inject and evaporate discrete water samples. The isotopic effects of variable air temperature, water vapour concentration, water pumping rate and dissolved organic content were found to be either negligible or correctable by analysis of water standards. The DS-CRDS system was used to analyse the O and H isotope composition in short-lived rain events. Other applications where finely time resolved water isotope data may be of benefit include recharge/discharge in groundwater/river systems and infiltration-related changes in cave drip water.
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http://dx.doi.org/10.1002/rcm.5282DOI Listing
December 2011

ISO-CADICA: isotopic-continuous, automated dissolved inorganic carbon analyser.

Rapid Commun Mass Spectrom 2012 Mar;26(6):639-44

Department of Earth and Environmental Science, James Cook University, Cairns Campus, Queensland, Australia.

Rationale: Quantifying the processes that control dissolved inorganic carbon (DIC) dynamics in aquatic systems is essential for progress in ecosystem carbon budgeting. The development of a methodology that allows high-resolution temporal data collection over prolonged periods is essential and is described in this study.

Methods: A novel sampling instrument that sequentially acidifies aliquots of water and utilises gas-permeable ePTFE tubing to measure the dissolved inorganic carbon (DIC) concentration and δ(13)C(DIC) values at sub-hourly intervals by Cavity Ring-down spectrometry (CRDS) is described.

Results: The minimum sensitivity of the isotopic, continuous, automated dissolved inorganic carbon analyser (ISO-CADICA) system is 0.01 mM with an accuracy of 0.008 mM. The analytical uncertainty in δ(13)C(DIC) values is proportional to the concentration of DIC in the sample. Where the DIC concentration is greater than 0.3 mM the analytical uncertainty is ±0.1‰ and below 0.2 mM stability is < ± 0.3‰. The isotopic effects of air temperature, water temperature and CO(2) concentrations were found to either be negligible or correctable. Field trials measuring diel variation in δ(13)C(DIC) values of coral reef associated sea water revealed significant, short-term temporal changes and illustrated the necessity of this technique.

Conclusions: Currently, collecting and analysing large numbers of samples for δ(13)C(DIC) measurements is not trivial, but essential for accurate carbon models, particularly on small scales. The ISO-CADICA enables on-site, high-resolution determination of DIC concentration and δ(13)C(DIC) values with no need for sample storage and laboratory analysis. The initial tests indicate that this system can offer accuracy approaching that of traditional IRMS analysis.
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http://dx.doi.org/10.1002/rcm.6143DOI Listing
March 2012

Monitoring of labile metals in turbid coastal seawater using diffusive gradients in thin-films.

J Environ Monit 2003 Feb;5(1):145-9

School of Biological, Environmental and Chemical Sciences, Northern Territory University, Darwin NT 0909, Australia.

Diffusive gradients in thin-films (DGT) have been investigated for in situ monitoring of labile metals in north Australian coastal seawater. Field and experimental data showed that DGT devices provided adequate detection limits, accuracy and precision for monitoring of near-pristine levels of labile Mn, Co, Cu, Cd and Pb when deployed for periods of 3 days. However, Zn could not be adequately determined due to high blank levels. The ratio of DGT-labile to 0.45 microm-filtered metal levels in natural seawater ranged from 0.44-0.63 for Cu but was close to unity for Co and Cd. Elevated levels of suspended particulate matter up to 57.3 mg l(-1) did not have an adverse effect on the performance of DGT.
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http://dx.doi.org/10.1039/b209346dDOI Listing
February 2003
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