Browsing by Author "Humphrey, C"
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- ItemThe effect of dissolved nickel and copper on the adult coral Acropora muricata and its microbiome(Elsevier, 2019-04-03) Gissi, F; Reichelt-Brushett, AJ; Chariton, AA; Stauber, JL; Greenfield, P; Humphrey, C; Salmon, M; Stephenson, SA; Cresswell, T; Jolley, DFThe potential impacts of mining activities on tropical coastal ecosystems are poorly understood. In particular, limited information is available on the effects of metals on scleractinian corals which are foundation species that form vital structural habitats supporting other biota. This study investigated the effects of dissolved nickel and copper on the coral Acropora muricata and its associated microbiota. Corals collected from the Great Barrier Reef were exposed to dissolved nickel (45, 90, 470, 900 and 9050 μg Ni/L) or copper (4, 11, 32 and 65 μg Cu/L) in flow through chambers at the National Sea Simulator, Townsville, Qld, Australia. After a 96-h exposure DNA metabarcoding (16S rDNA and 18S rDNA) was undertaken on all samples to detect changes in the structure of the coral microbiome. The controls remained healthy throughout the study period. After 36 h, bleaching was only observed in corals exposed to 32 and 65 μg Cu/L and very high nickel concentrations (9050 μg Ni/L). At 96 h, significant discolouration of corals was only observed in 470 and 900 μg Ni/L treatments, the highest concentrations tested. While high concentrations of nickel caused bleaching, no changes in the composition of their microbiome communities were observed. In contrast, exposure to copper not only resulted in bleaching, but altered the composition of both the eukaryote and bacterial communities of the coral's microbiomes. Our findings showed that these effects were only evident at relatively high concentrations of nickel and copper, reflecting concentrations observed only in extremely polluted environments. Elevated metal concentrations have the capacity to alter the microbiomes which are inherently linked to coral health. Crown Copyright ©2019. Published by Elsevier Ltd.
- ItemOPAL engineering early modifications relating to AOC: loss of offsite power (LOOP)(International Group On Research Reactors, 2010-09-19) Metcalf, P; Humphrey, CNot available
- ItemOPAL engineering strategies to manage neutron guide seal leaks(European Nuclear Society, 2012-03-18) Humphrey, C; Metcalf, PIn the first two years following hot commissioning of the OPAL Reactor in 2006 light water leaks were detected in all five (5) bellows leak detection chambers of helium guide cooling system. These seals from part of the primary LOCA barrier for the reactor pool. To date no water has been detected past the double metallic C-seals of the neutron beam assemblies into the assembly boxes. This paper reports strategies implemented by the OPAL Engineering group to manage current leak rates and deal with any future escalation leaks. These include: changes to the reactor control and monitoring system to enable ongoing reactor operation, automation of drainage operation, installation of pool water leak recycling system, design provisions for helium back pressurisation and in-pool mechanical collar seals. The system approved and implemented on the reactor ensure that leaked water is drained from the inter seal void space to limit pressure on the inner seal. The system includes remote real time indication and warning of leak rates and is capable of handling leak rates up to 0.5 m3/h. By automatically recycling water drainage, the system reduced plant radioactive liquid waste discharges and operator dose rates to ALARA.
- ItemThe response of corals and the coral microbiome to metal exposure(Society of Environmental Toxicology and Chemistry, 2017-11-12) Gissi, F; Reichelt-Brushett, AJ; Chariton, AA; Stauber, JL; Stephenson, SA; Cresswell, T; Greenfield, P; Severati, A; Humphrey, C; Jolley, DFThe mining and production of Ni is increasing in tropical regions. The potential impacts of these activities on the valuable coastal ecosystems are poorly understood. Specifically, there is little information available on the effects of Ni to corals. Scleractinian corals are keystone species for coral reefs forming vital structural habitats that support other species, resulting in habitats with high species richness and diversity. For these reasons, it is important that future research provides data which can inform the sustainable development of Ni operations in tropical regions. This study aimed to investigate the effect of dissolved Ni exposure to the scleractinian coral Acropora muricata. Utilising the facilities at the National Sea Simulator (SeaSim), flow through chambers (2.5L) were used to test the effects of Ni and Cu on adult corals and its associated microbiota. Copper was tested alongside Ni to allow for comparisons with past studies. Four replicate chambers were used for; control, 50, 100, 500, 1000, 10000 µg/L Ni and 5, 20, 50, 100 µg/L Cu. Each replicate chamber contained 3 coral fragments (5-8cm in length). After a 96-h exposure, 1 fragment from each chamber was sacrificed for 3 different analytical purposes. One replicate was air blasted to remove tissues which were flash frozen and later used for DNA and RNA sequencing of the microbiota to observe if the bacterial community structure changed in response to metal exposure. A second fragment was air blasted to remove tissues, which were then acid digested and analysed by ICP-MS to determine metal concentrations in the coral tissues. A third replicate was frozen for subsequent metal uptake and distribution analyses using elemental mapping techniques including CT scanning and XRF-ITRAX. Control treatments remained healthy throughout the exposure. After 36 h, bleaching was observed in corals exposed to 50 and 100 µg Cu/L and 10000 µg Ni/L. At 96 h significant discolouration of corals was observed in Ni treatments 500 and 1000 µg Ni/L. The effects of Cu and Ni on adult corals and associated microbiota will be discussed.
- ItemSecondary cooling system ageing management and refurbishment activities at the OPAL Reactor(IGORR : International Group on Research Reactors and International Atomic Energy Agency, 2021-05-31) Humphrey, CNot available