Browsing by Author "Carolan, JV"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Biokinetics and discrimination factors for delta C-13 and delta N-15 in the omnivorous freshwater crustacean, Cherax destructor
    (CSIRO Publishing, 2012-10-29) Carolan, JV; Mazumder, D; Dimovski, C; Diocares, R; Twining, JR
    Knowledge and understanding of biokinetics and discrimination factors for carbon-13 (delta C-13) and nitrogen-15 (delta N-15) are important when using stable isotopes for food-web studies. Therefore, we performed a controlled laboratory diet-switch experiment to examine diet-tissue and diet-faeces discrimination factors as well as the biokinetics of stable-isotope assimilation in the omnivorous freshwater crustacean, Cherax destructor. The biokinetics of delta C-13 could not be established; however, the delta N-15 value of C. destructor tissue reached equilibrium after 80 +/- 35 days, with an estimated biological half-time for N-15 of 19 +/- 5 days. Metabolic activity contributed to the turnover of N-15 by nearly an order of magnitude more than growth. The diet-tissue discrimination factors at the end of the exposure were estimated as -1.1 +/- 0.5% for delta C-13 and +1.5 +/- 1.0% for delta N-15, indicating that a delta N-15 diet-tissue discrimination factor different from the typically assumed +3.4% may be required for freshwater macroinvertebrates such as C. destructor. The diet-faeces discrimination factor for delta N-15 after 120 days was estimated as +0.9 +/- 0.5%. The present study provides an increased understanding of the biokinetics and discrimination factors for a keystone freshwater macroinvertebrate that will be valuable for future food-web studies in freshwater ecosystems. © 2012, CSIRO Publishing.
  • Thumbnail Image
    Item
    Dose assessment for marine biota and humans from discharge of (131)I to the marine environment and uptake by algae in Sydney, Australia
    (Elsevier, 2009-10-12) Carolan, JV; Hughes, CE; Hoffmann, EL
    Iodine-131 reaches the marine environment through its excretion to the sewer by nuclear medicine patients followed by discharge through coastal and deepwater outfalls. 131I has been detected in macroalgae, which bio-accumulate iodine, growing near the coastal outfall of Cronulla sewage treatment plant (STP) since 1995. During this study, 131I levels in liquid effluent and sludge from three Sydney STPs as well as in macroalgae (Ulva sp. and Ecklonia radiata) growing near their shoreline outfalls were measured. Concentration factors of 176 for Ulva sp. and 526 for E. radiata were derived. Radiation dose rates to marine biota from 131I discharged to coastal waters calculated using the ERICA dose assessment tool were below the ERICA screening level of 10 μGy/hr. Radiation dose rates to humans from immersion in seawater or consumption of Ulva sp. containing 131I were three and two orders of magnitude below the IAEA screening level of 10 μSv/year, respectively. year, respectively. Crown Copyright © 2009 Published by Elsevier Ltd