Browsing by Author "Zernack A"

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    Comparative evaluation of pumice as a soilless substrate for indoor Rubus idaeus L. cultivation
    (Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024-07-21) Zhao R; Sofkova-Bobcheva S; Cartmill DL; Hardy D; Zernack A; Li M
    Pumice is an abundant natural resource in New Zealand and its application in horticulture could save significant costs. To investigate the effect of pumice substrates on raspberry growth and fruit quality, two dwarfing selections (sel.8 and sel.110) were grown hydroponically in (1) coconut coir (control); (2) pumice; (3) pumice/coir (50/50 v/v); (4) pumice/flax (50/50 v/v). Results showed that the addition of pumice to coir significantly increased bulk density, which provided better root anchor support for plants, and also increased the water holding capacity (WHC). Pure pumice had a higher bulk density and lower porosity compared to the other tested substrates, which enhanced fruit quality and yield, although the vegetative growth was slightly lower compared to the control. Mixed pumice/flax substrate had the lowest porosity and poorer WHC, resulting in inferior raspberry growth vigour and productivity. Our results furthermore suggested different substrates could affect the one-year-old cane height, crop yield and fruit characteristics. Pumice was more suitable for sel.8, while the pumice/coir mixture promoted a higher yield for sel.110. In conclusion, pumice and pumice-based mix substrates can be successfully used for hydroponic dwarfing raspberry production without compromising yield and fruit quality.
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    Geochemical fingerprinting of Holocene tephras in the Willaumez Isthmus District of West New Britain, Papua New Guinea
    (The Australian Museum, 2021-05-12) Neall V; McGee L; Turner M; O'Neill T; Zernack A; Athens JS; Specht, J; Attenbrow, V; Allen, J
    Electron microprobe analyses were conducted on volcanic glasses extracted from Holocene tephra marker beds on the Willaumez isthmus in West New Britain, Papua New Guinea. These tephra beds are pivotal in the dating of a wide range of human artefacts and manuports found in the intervening buried soils, extending back over the last 40,000 years. Three major groups can be easily separated: W-K1 and 2; W-K3 and 4; and the Dakataua tephra. Of the remaining post-W-K4 tephras, most show slightly higher FeO and CaO and lower SiO2 contents than the W-K3 and 4 group, although there is some overlap. The combination of these geochemical data sets with the known stratigraphy and radiocarbon dates has helped resolve tephra correlation where these ashes become thin and less visually diagnostic or where pumice has been resorted and redeposited by the Kulu-Dulagi River.
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    Stratigraphy and lithosedimentological properties of subplinian eruptions from Mt. Taranaki, New Zealand, encompassed by the Ngaere and Pungarehu edifice collapses
    (Taylor and Francis Group, 2025-01-29) Mills S; Procter J; Zernack A; Mead S
    The sudden removal of large portions of a volcanic edifice through collapse can cause depressurisation in the subvolcanic magmatic system, influencing the nature of subsequent eruptions. At Mt. Taranaki, edifice failure has occurred frequently and at different timescales throughout the volcanic history, forming a broad pattern of cyclic collapse and regrowth. About 20–30,000 years ago, Mt. Taranaki experienced two such cycles in short succession, emplacing the 27.3 ka Ngaere and the 24.8 ka Pungarehu debris-avalanche deposits, which were preceded and followed by a sequence of twenty-eight closely spaced tephra deposits known as the Poto and Paetahi Formations. Here, we reconstruct the tephrastratigraphic framework of the Poto and Paetahi Formations, revealing a minimum total eruptive volume of 3 km3. While eruptions directly following edifice failure were larger compared to those prior to collapse, this 4,000-year long eruptive period was characterised by consistently large subplinian eruptions. In contrast, large explosive events within the Holocene sequence are less frequent, with more multi-phase periods of effusive and explosive activity recorded. Our new data highlights the need to include longer-term eruptive records in volcanic hazard modelling since the most recent volcanic history might not cover the full nature of volcanic processes occurring at long-lived stratovolcanoes.