https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:14156 14C response, presumed to be related to site characteristics such as vegetation, temperature, rainfall, depth below the surface, and water pathway through the aquifer. Peak ¹⁴C activity for WM4 is 134.1 pMC, the highest cited thus far in the literature and suggestive of a lower inertia at this site. Dead carbon fractions for each stalagmite were calculated and found to be relatively similar for the 3 speleothems and lower than those derived from Northern Hemisphere speleothems. An inverse modeling technique based on the work of Genty and Massault (1999) was used to estimate soil carbon residence times. For each speleothem, mean soil 14C reservoir ages differed greatly between the 3 sites, ranging from 2–6.5 to 32–46 yr.]]> Wed 11 Apr 2018 16:39:29 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:17747 DIC and drip rate depend on the local structural setting and water path length. The data presented show that Galleria delle Stalattiti (the focus of the paleoclimate research) has the most stable conditions in terms of temperature, and the dripwaters show constant pH, electrical conductivity, alkalinity, calcium and magnesium content and δ¹⁸O. Drip rate is not affected by rain events and displays long-term trends that require a longer period of monitoring for elucidating their nature. The preliminary data presented here corroborate the hypotheses suggesting Galleria delle Stalattiti as a good example of a “deep” hypogean system of Fairchild et al. (2007).]]> Wed 11 Apr 2018 13:25:52 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:17140 Wed 11 Apr 2018 13:06:31 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:31155 Wed 11 Apr 2018 11:49:04 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:23439 Wed 11 Apr 2018 11:39:09 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:11218 Wed 11 Apr 2018 10:32:36 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:17139 p) rather than the thermodynamic partition coefficient (K_p) to account for the presence of crystalline phosphate inclusions. SK_p describes P enrichment in speleothems regardless of the process, as similar mechanisms of phosphate co-precipitation may be in operation in biotic and abiotic conditions. The most important implication of our study is that variability in P concentration may be related to diverse processes which can be recognized through petrographic observations and chemical mapping. In particular, there may not be a direct relation between an increase in P concentration and seasonal infiltration as has been found in some previous studies, especially if the source of this element is not the labile phosphate released through leaching during seasonal vegetation dieback in temperate climates.]]> Wed 11 Apr 2018 10:30:22 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30186 14C ages ranged from 2232 to 2889 cal yr BP, with 95.4% probability age range in the youngest and oldest samples of 2153–2337 and 2342–3449 cal yr BP respectively. The median age of the more modern dripstone was 336 cal yr BP, with a 95.4% probability age range of 148–486 cal yr BP. These results provide very approximate ball-park estimates of the age of the sample, but are consistently too old when compared to the known maximum ages of formation. It is hypothesised that this offset is due to a combination of the nature of the organic carbon transported from the source organic matter pools, and reworking of both modern and old organic carbon by in situ microbial communities.]]> Wed 04 Sep 2019 09:39:24 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:36295 Tue 24 Mar 2020 09:23:30 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:41756 Tue 21 Mar 2023 18:48:39 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:36369 Thu 02 Apr 2020 13:48:31 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49220 Sun 07 May 2023 09:37:55 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:8023 Sat 24 Mar 2018 08:36:49 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:8050 Sat 24 Mar 2018 08:35:02 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:1222 Sat 24 Mar 2018 08:28:30 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:1701 0 °C at a time when MIS 6 ice volumes were close to their maximum. High stable carbon isotope (δ¹³C) values (−2.8‰ to +3.1‰) throughout the stalagmite's growth reflect a persistently low input of biogenic CO², indicating that the steep, barren and alpine-like recharge area of today has been in existence for at least the last ∼380 kyr. During MIS 9, the lowest δ¹³C values occur well after maximum interglacial conditions, suggesting a lag in the development of post-glacial soils in this high-altitude karst. The stable oxygen isotope (δ¹⁸O) trends match the main structural features of the major climate proxy records (SPECMAP, Vostok and Devils Hole), suggesting that the δ¹⁸O of CC1 has responded to global-scale climate changes, whilst remarkable similarity exists between CC1 δ¹⁸O and regional sea-surface temperature reconstructions from North Atlantic core ODP980 and southwest Pacific marine core MD97-2120 through the most detailed part of the CC1 record, MIS 9–8. The results suggest that CC1 and other stalagmites from the cave have the potential to capture a long record of regional temperature trends, particularly in regards to the relative severity of Pleistocene glacial stages.]]> Sat 24 Mar 2018 08:27:20 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:11437 Sat 24 Mar 2018 08:14:36 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:11476 Sat 24 Mar 2018 08:10:27 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19954 Sat 24 Mar 2018 07:58:33 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:5064 Sat 24 Mar 2018 07:48:53 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:5267 Sat 24 Mar 2018 07:46:33 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:4999 Sat 24 Mar 2018 07:44:08 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:5381 Sat 24 Mar 2018 07:43:55 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:27242 100 nm) of soils, but in the fine colloidal (< 100 nm) and nominally dissolved (< 1 nm) fractions of dripwaters. The concentration of Cu, Ni and Co in dripwater samples across all sites were well correlated (R2 = 0.84 and 0.70, Cu vs. Ni, Cu vs. Co, respectively), indicating a common association. Furthermore, metal ratios (Cu:Ni, Cu:Co) were consistent with NICA-Donnan n1 humic binding affinity ratios for these metals, consistent with a competitive hierarchy of binding affinity (Cu > Ni > Co) for sites in colloidal or dissolved NOM. Large shifts in Cu:Ni in dripwaters coincided with high fluxes of particulate OC (following peak infiltration) and showed increased similarity to ratios in soils, diagnostic of qualitative changes in NOM supply (i.e. fresh inputs of more aromatic/hydrophobic soil organic matter (SOM) with Cu outcompeting Ni for suitable binding sites). Results indicate that at high-flows (i.e. where fracture-fed flow dominates) particulates and colloids migrate at similar rates, whereas, in slow seepage-flow dripwaters, particulates (> 1 μm) and small colloids (1–100 nm) decouple, resulting in two distinct modes of NOM–metal transport: high-flux and low-flux. At the hyperalkaline drip site PE1 (in Poole's Cavern), high-fluxes of metals (Cu, Ni, Zn, Ti, Mn, Fe) and particulate NOM occurred in rapid, short-lived pulses following peak infiltration events, whereas low-fluxes of metals (Co and V > Cu, Ni and Ti) and fluorescent NOM (< ca. 100 nm) were offset from infiltration events, probably because small organic colloids (1–100 nm) and solutes (< 1 nm) were slower to migate through the porous matrix than particulates. These results demonstrate the widespread occurrence of both colloidal and particulate NOM–metal transport in cave dripwaters and the importance of karst hydrology in affecting the breakthrough times of different species. Constraints imposed by soil processes (colloid/particle release), direct contributions of metals and NOM from rainfall, and flow-routing (colloid/particle migration) are expected to determine the strength of correlations between NOM-transported metals in speleothems and climatic signals. Changes in trace metal ratios (e.g. Cu:Ni) in speleothems may encode information on NOM composition, potentially aiding in targeting of compound-specific investigations and for the assessment of changes in the quality of soil organic matter.]]> Sat 24 Mar 2018 07:29:08 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3318 Sat 24 Mar 2018 07:23:17 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:4911 Sat 24 Mar 2018 07:22:58 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:4749 Sat 24 Mar 2018 07:21:08 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3183 Sat 24 Mar 2018 07:18:09 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:24615 _inf) ranging from 355 to 2400 m a.s.l., corresponding to infiltration mean annual temperatures (MAT_inf) between 12 and 0 °C. Since all the caves developed in pure carbonate rocks, soil pCO₂ is found to be the main factor controlling the carbonate dissolution. For this reason, the parameters controlling the carbonate-carbonic acid system and calcite saturation state (SICC) are directly correlated with the MAT_inf, which influences the vegetation zones and eventually the production of CO₂ in the soil. SI_CC linearly depends on MAT_inf (SI_CC = 0.09 MAT_inf - 0.4) and SI_CC = 0 is reached at Z_inf = 1.66 km a.s.l., corresponding to a MAT_inf = 4.4 °C. This point identifies the "speleothem limit" defined here as the elevation (or corresponding MAT_inf) above which no sparitic speleothem precipitation usually occurs. We demonstrate that due to temperature-forced changes in the soil and vegetation and subsequently SI_CC, the speleothem limit shifts to higher altitudes during maximum interglacial conditions. Speleothems from high altitude caves (1.5-2.5 km a.s.l.) thus can identify optimum interglacial periods. By contrast, speleothems formed at lower altitudes are better suited as archives of hydrological proxies. At altitudes below 1.2 km a.s.l., prior calcite precipitation (PCP) modifies percolating waters, particularly during periods of reduced infiltration. We introduce the use of the SiO₂/Ca and SO₄/Ca ratios in cave waters to complement Mg/Ca and Sr/Ca ratios as markers of PCP. SO₄ and SiO₂ are derived from atmospheric deposition and siliciclastic minerals in the soil zone, rather than carbonate host rocks (as in the case of Mg and Sr). By combing shifts to higher Mg/Ca, SiO₂/Ca and SO₄/Ca ratios along their characteristics PCP lines, we improve the robustness of the interpretation that this resulted from increasing PCP, rather than incongruent calcite dissolution (ICD). Our method permits the quantification of PCP between 0% and 40% for low elevation cave waters. This novel approach has important implications for speleothem-based paleoclimate studies where the distinction between PCP and ICD can be ambiguous and, in combination with Mg/Ca and Sr/Ca ratios, permits the quantification of net infiltration and/or rainfall amount from speleothem records.]]> Sat 24 Mar 2018 07:11:54 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:25047 Sat 24 Mar 2018 07:10:46 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:52766 Mon 29 Jan 2024 18:40:13 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:35499 Mon 13 Mar 2023 15:06:27 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39226 Fri 27 May 2022 11:58:26 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40174 18O of two coeval modern speleothems from Cathedral Cave, Wellington, in semi-arid SE Australia are compared to the instrumental record to assess its efficacy as a proxy of past hydrological variability. Stalagmite δ¹⁸O was modulated by the frequency of recharge events and epikarst evaporation of storage water. Prolonged intervals between recharge events, such as droughts, resulted in higher stalagmite δ¹⁸O. Conversely, periods with more frequent recharge events and a positive water balance, resulted in lower δ¹⁸O. Disequilibrium cave processes are likely to be enhanced during dry conditions, although it is argued that these will modulate δ¹⁸O_spel in the same direction as epikarst evaporation, effectively amplifying the response of δ¹⁸O_spel. Extreme events, such as floods and droughts, were also captured in the stalagmite records, although potentially with a lag of several years. We verify that modern speleothems from semi-arid regions can be used to reconstruct hydroclimate due to variations in δ¹⁸O_spel modulated by karst processes. Such records are archives of past changes in recharge rather than precipitation amount or surface temperature, as is commonly applied to speleothem records from non-water-limited regions.]]> Fri 22 Jul 2022 13:55:20 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49771 Fri 02 Jun 2023 17:37:40 AEST ]]>