scholarly journals Radiocarbon Variations from Tasmanian Conifers: Results from Three Early Holocene Logs

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Mike Barbetti ◽  
Trevor Bird ◽  
George Dolezal ◽  
Gillian Taylor ◽  
Roger Francey ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Calibration Curve ◽  
The Other ◽  
Early Holocene ◽  
Conifer Species ◽  
Middle Holocene ◽  
Calibration Curves ◽  
Lagarostrobos Franklinii ◽  
Floodplain Sediments ◽  
Good Coverage

Dendrochronological studies are being carried out on two conifer species in the Stanley River area of western Tasmania. The chronology for Huon pine (Lagarostrobos franklinii), with living trees up to 1400 yr old, extends back to 571 bc. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 yr old. Apart from living or recently felled trees, sections have been taken from 350 subfossil logs preserved in floodplain sediments. They range in age from >38 ka to modern, with good coverage for the periods 9–3.5 ka and from 2.5 ka to the present. We report here on 14C measurements of decadal samples from three early Holocene logs, between 10 and 9 ka bp, providing short (ca. 300-yr) records of atmospheric 14C variations when plotted against ring numbers. The southern hemisphere data from Tasmania can be compared and wiggle-matched with published 14C calibration curves from German oak and pine. One set of measurements covers the period, ca. 9280–8990 cal bp, overlapping the link between the Hohenheim “Main 9” and middle Holocene master oak chronologies. The other sets of measurements from Tasmania coincide; they span the period, ca. 9840–9480 cal bp, overlapping the end of the German Preboreal pine and the beginning of the oak chronologies. Our measurements confirm that this part of the calibration curve is a gently sloping 14C-age plateau (ca. 8900–8700 bp, between 10,000 and 9500 cal bp), and suggest interhemispheric 14C differences close to zero.

scholarly journals Radiocarbon Variations from Tasmanian Conifers: First Results from Late Pleistocene and Holocene Logs

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 806-817 ◽  
Author(s):  
Mike Barbetti ◽  
Trevor Bird ◽  
George Dolezal ◽  
Gillian Taylor ◽  
Roger Francey ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Late Pleistocene ◽  
Conifer Species ◽  
Calibration Curves ◽  
Bristlecone Pine ◽  
First Results ◽  
Lagarostrobos Franklinii ◽  
Zero Offset ◽  
Floodplain Sediments ◽  
Good Agreement

Dendrochronological studies have begun on two conifer species in the Stanley River area of western Tasmania. The chronology extends to 273 BC for Huon pine (Lagarostrobos franklinii) and to AD 1450 for celery-top pine (Phyllocladus aspleniifolius). Apart from living or recently felled trees, sections have been taken from 58 logs preserved in floodplain sediments. Two of these logs have late Pleistocene ages, centered around 13.0 and 12.7 k 14C yr bp. Four logs are between 8 and 9 ka BP, and one is centered at 7.3 ka bp. The remaining logs have various ages between 6.2 ka BP and the present. 14C measurements have been performed on decadal samples from the two late Pleistocene logs, providing short (260-yr) records of atmospheric 14C variations when plotted against individual ring numbers. Decadal measurements on the 7300-yr-old log have been wiggle-matched with 14C calibration curves from German oak and bristlecone pine. Measurements for the period, AD 1600–1800, show good agreement with northern hemisphere results, and a nearly zero offset between the hemispheres.

scholarly journals Bayesian Evaluation of the Southern Hemisphere Radiocarbon Offset during the Holocene

Radiocarbon ◽  
2009 ◽  
Vol 51 (4) ◽  
pp. 1165-1176 ◽  
Author(s):  
Alan Hogg ◽  
Christopher Bronk Ramsey ◽  
Chris Turney ◽  
Jonathan Palmer
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Calibration Curve ◽  
Early Holocene ◽  
Data Sets ◽  
Bayesian Calibration ◽  
The Holocene ◽  
Calibration Program

While an interhemispheric offset in atmospheric radiocarbon levels from AD 1950–950 is now well established, its existence earlier in the Holocene is less clear, with some studies reporting globally uniform 14C levels while others finding Southern Hemisphere samples older by a few decades. In this paper, we present a method for wiggle-matching Southern Hemisphere data sets against Northern Hemisphere curves, using the Bayesian calibration program OxCal 4.1 with the Reservoir Offset function accommodating a potential interhemispheric offset. The accuracy and robustness of this approach is confirmed by wiggle-matching known-calendar age sequences of the Southern Hemisphere calibration curve SHCal04 against the Northern Hemisphere curve IntCal04. We also show that 5 of 9 Holocene Southern Hemisphere data sets are capable of yielding reliable offset information. Those data sets that are accurate and precise show that interhemispheric offset levels in the Early Holocene are similar to modern levels, confirming SHCal04 as the curve of choice for calibrating Southern Hemisphere samples.

scholarly journals High-Precision Radiocarbon Measurements of Tree-Ring Dated Wood from New Zealand: 195 Bc–Ad 995

Radiocarbon ◽  
2011 ◽  
Vol 53 (3) ◽  
pp. 529-542 ◽  
Author(s):  
Alan Hogg ◽  
Jonathan Palmer ◽  
Gretel Boswijk ◽  
Chris Turney
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Calibration Curve ◽  
Geographic Location ◽  
Temporal Variations ◽  
Time Interval ◽  
Data Sets ◽  
Data Set ◽  
Data Points ◽  
Lagarostrobos Franklinii

The best means for correcting Southern Hemisphere (SH) radiocarbon measurements, which are significantly influenced by temporal variations in the interhemispheric offset, is by the construction of a SH-specific calibration curve from dendrochronologically dated wood. We present here decadal 14C measurements on dendrochronologically secure New Zealand kauri (Agathis australis), covering the period 195 BC–AD 995, extending the range of calibration measurements from New Zealand tree rings to more than 2 millennia.Recently published Tasmanian huon pine (Lagarostrobos franklinii) data for the interval 165 BC to AD 1095 measured at the Center for Accelerator Mass Spectrometry (CAMS) have underestimated standard errors, which need to be re-assessed before the data can be considered for a Southern Hemisphere calibration curve update. The CAMS huon data, unlike the Waikato kauri data presented here, show a significant reduction in the SH offset for the interval AD 775–855. Although these data points are being checked, it is unlikely this represents a temporal geographic location-dependent offset. With re-assessed errors, the huon data set from 165 BC to AD 995 closely matches the new kauri data, with the combined data sets producing a mean interhemispheric offset with IntCal09 of 44 ± 17 yr for the time interval 195 BC–AD 1845. This SH offset is lower than the modeled offset of 55–58 yr used in the construction of SHCal04, and we recommend the lower value be used in future SHCal updates. Although there is an apparent increase in higher frequency events in the SH offset (NZ kauri plus Tasmanian huon) from 200 BC–AD 1000, the reason for this remains unclear.

scholarly journals The oldest hexanchiform shark from the Southern Hemisphere (Neoselachii; Early Cretaceous, Antarctica)

2009 ◽  
Vol 21 (5) ◽  
pp. 501-504 ◽  
Author(s):  
Alberto Luis Cione ◽  
Francisco Medina
Keyword(s):  
Southern Hemisphere ◽  
Antarctic Peninsula ◽  
Early Cretaceous ◽  
The Other ◽  
James Ross Island

AbstractThe oldest record of the hexanchiform sharks from the Southern Hemisphere and the second chondrichthyan report known from Carboniferous to Early Cretaceous beds in Antarctica is given. The material was collected in late Aptian rocks of the Kotick Point Formation outcropping in the western part of James Ross Island, near Antarctic Peninsula. It consists of an isolated tooth assignable to a hexanchiform different from the other described genera. The tooth shows putative plesiomorphic cusp (few cusps, no serrations) and apomorphic root characters (relatively deep, quadrangular). It could be related to a species close to the origin ofHexanchus(unknown in beds older than Cenomanian).

Distribution of leaf orientations in six conifer species

2001 ◽  
Vol 79 (4) ◽  
pp. 389-397 ◽  
Author(s):  
Hugh J Barclay
Keyword(s):  
Pseudotsuga Menziesii ◽  
Pinus Contorta ◽  
Goodness Of Fit ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
The Other ◽  
Thuja Plicata ◽  
Leaf Angle ◽  
Conifer Species ◽  
Abies Grandis

Leaf angle distributions are important in assessing both the flexibility of a plant's response to differing daily and seasonal sun angles and also the variability in the proportion of total leaf area visible in remotely sensed images. Leaf angle distributions are presented for six conifer species, Abies grandis (Dougl. ex D. Don) Lindl., Thuja plicata Donn. ex D. Don, Tsuga heterophylla (Raf.) Sarg., Pseudotsuga menziesii (Mirb.) Franco, Picea sitchensis (Bong.) Carr. and Pinus contorta Dougl. ex Loud. var. latifolia. The leaf angles were calculated by measuring four foliar quantities, and then the distributions of leaf angles are cast in three forms: distributions of (i) the angle of the long axis of the leaf from the vertical for the range 0–180°; (ii) the angle of the long axis of the leaf for the range 0–90°; and (iii) the angle of the plane of the leaf for the range 0–90°. Each of these are fit to the ellipsoidal distribution to test the hypothesis that leaf angles in conifers are sufficiently random to fit the ellipsoidal distribution. The fit was generally better for planar angles and for longitudinal angles between 0° and 90° than for longitudinal angles between 0° and 180°. The fit was also better for Tsuga heterophylla, Pseudotsuga menziesii, Picea sitchensis, and Pinus contorta than for Abies grandis and Thuja plicata. This is probably because Abies and Thuja are more shade tolerant than the other species, and so the leaves in Abies and Thuja are preferentially oriented near the horizontal and are much less random than for the other species. Comparisons of distributions on individual twigs, whole branches, entire trees, and groups of trees were done to test the hypothesis that angle distributions will depend on scale, and these comparisons indicated that the apparent randomness and goodness-of-fit increased on passing to each larger unit (twigs up to groups of trees).Key words: conifer, leaf angles, ellipsoidal distribution.

scholarly journals Is there any Evidence for Regional Atmospheric 14C Offsets in the Southern Hemisphere?

Radiocarbon ◽  
2013 ◽  
Vol 55 (4) ◽  
pp. 2029-2034 ◽  
Author(s):  
Alan Hogg ◽  
Chris Turney ◽  
Jonathan Palmer ◽  
Ed Cook ◽  
Brendan Buckley
Keyword(s):  
Mass Spectrometry ◽  
New Zealand ◽  
Southern Hemisphere ◽  
Accelerator Mass Spectrometry ◽  
Time Interval ◽  
Common Time ◽  
Lagarostrobos Franklinii

Center for Accelerator Mass Spectrometry (CAMS) Tasmanian Huon pine (Lagarostrobos franklinii) decadal measurements for the interval AD 745–855 suggest a mean interhemispheric radiocarbon offset (20 ± 5 yr), which is considerably lower than the previously reported mean interhemispheric offset for the last 2 millennia (44 ± 17 yr). However, comparable University of Waikato (Wk) New Zealand kauri (Agathis australis) measurements show significantly higher values (56 ± 6 yr), suggesting the possibility of a temporary geographic (intrahemispheric) offset between Tasmania, Australia, and Northland, New Zealand, during at least 1 common time interval. Here, we report 9 new Wk Tasmanian Huon pine measurements from the decades showing the largest Huon/kauri difference. We show statistically indistinguishable Wk Huon and Wk kauri 14C ages, thus dispelling the suggestion of a 14C geographic offset between Tasmania and Northland.

scholarly journals Validation of an LC-MS/MS Method for the Quantification of Caffeine and Theobromine Using Non-Matched Matrix Calibration Curve

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2863 ◽  
Author(s):  
Vera M. Mendes ◽  
Margarida Coelho ◽  
Angelo R. Tomé ◽  
Rodrigo A. Cunha ◽  
Bruno Manadas
Keyword(s):  
Human Plasma ◽  
Calibration Curve ◽  
Considerable Effort ◽  
Caffeine Consumption ◽  
Internal Standards ◽  
Beneficial Effects ◽  
Calibration Curves ◽  
Accuracy And Precision ◽  
Precise Quantification ◽  
Surrogate Matrix

Caffeine is one of the most widely consumed psycho-stimulants. The study of the beneficial effects of caffeine consumption to decrease the risk of developing several neuropsychiatric pathologies is receiving increasing attention. Thus, accurate and sensitive methods have been developed, mainly by LC-MS/MS, in order to quantify caffeine and its metabolites. These quantifications of caffeine and its metabolites by LC-MS/MS require a considerable effort to select or find a surrogate matrix, without the compounds of interest, to be used in the calibration curves. Thus, we evaluated the possibility of using calibration curves prepared in solvent instead of calibration curves prepared in human plasma. Results show that the calibration curves prepared in solvent and in human plasma were similar by comparing their slopes and interceptions, and the accuracy and precision were within the limits of acceptance for both calibration curves. This work demonstrates that, by using internal standards, it is possible to use a calibration curve in solvent instead of a calibration curve in plasma to perform an accurate and precise quantification of caffeine and theobromine.

Climate Response to External Sources of Freshwater: North Atlantic versus the Southern Ocean

2007 ◽  
Vol 20 (3) ◽  
pp. 436-448 ◽  
Author(s):  
Ronald J. Stouffer ◽  
Dan Seidov ◽  
Bernd J. Haupt
Keyword(s):  
Southern Ocean ◽  
Southern Hemisphere ◽  
North Atlantic ◽  
Surface Waters ◽  
Real World ◽  
The Other ◽  
Sea Surface ◽  
The North ◽  
The North Atlantic ◽  
The Antarctic

Abstract The response of an atmosphere–ocean general circulation model (AOGCM) to perturbations of freshwater fluxes across the sea surface in the North Atlantic and Southern Ocean is investigated. The purpose of this study is to investigate aspects of the so-called bipolar seesaw where one hemisphere warms and the other cools and vice versa due to changes in the ocean meridional overturning. The experimental design is idealized where 1 Sv (1 Sv ≡ 106 m3 s−1) of freshwater is added to the ocean surface for 100 model years and then removed. In one case, the freshwater perturbation is located in the Atlantic Ocean from 50° to 70°N. In the second case, it is located south of 60°S in the Southern Ocean. In the case where the North Atlantic surface waters are freshened, the Atlantic thermohaline circulation (THC) and associated northward oceanic heat transport weaken. In the Antarctic surface freshening case, the Atlantic THC is mainly unchanged with a slight weakening toward the end of the integration. This weakening is associated with the spreading of the fresh sea surface anomaly from the Southern Ocean into the rest of the World Ocean. There are two mechanisms that may be responsible for such weakening of the Atlantic THC. First is that the sea surface salinity (SSS) contrast between the North Atlantic and North Pacific is reduced. And, second, when freshwater from the Southern Ocean reaches the high latitudes of the North Atlantic Ocean, it hinders the sinking of the surface waters, leading to the weakening of the THC. The spreading of the fresh SSS anomaly from the Southern Ocean into the surface waters worldwide was not seen in earlier experiments. Given the geography and climatology of the Southern Hemisphere where the climatological surface winds push the surface waters northward away from the Antarctic continent, it seems likely that the spreading of the fresh surface water anomaly could occur in the real world. A remarkable symmetry between the two freshwater perturbation experiments in the surface air temperature (SAT) response can be seen. In both cases, the hemisphere with the freshwater perturbation cools, while the opposite hemisphere warms slightly. In the zonally averaged SAT figures, both the magnitude and the pattern of the anomalies look similar between the two cases. The oceanic response, on the other hand, is very different for the two freshwater cases, as noted above for the spreading of the SSS anomaly and the associated THC response. If the differences between the atmospheric and oceanic responses apply to the real world, then the interpretation of paleodata may need to be revisited. To arrive at a correct interpretation, it matters whether or not the evidence is mainly of atmospheric or oceanic origin. Also, given the sensitivity of the results to the exact details of the freshwater perturbation locations, especially in the Southern Hemisphere, a more realistic scenario must be constructed to explore these questions.

scholarly journals Prochelator tupuhi sp. nov., the first record of Desmosomatidae Sars, 1897 (Crustacea: Isopoda) from New Zealand waters

Zootaxa ◽  
2008 ◽  
Vol 1866 (1) ◽  
pp. 482 ◽  
Author(s):  
SASKIA BRIX ◽  
NIEL L. BRUCE
Keyword(s):  
New Species ◽  
New Zealand ◽  
Southern Hemisphere ◽  
Lateral Lobe ◽  
First Record ◽  
The Other ◽  
The Family

Prochelator tupuhi sp. nov. is the first record of the genus Prochelator Hessler, 1970 from Southern Hemisphere waters, and the first record of the family Desmosomatidae from New Zealand. The new species can be distinguished from all other species of the genus by the following characters: body elongate, without spine-like ventral elongations on pereonites 1–4, pereonite 1 as high as pereonite 5, mesial lobe of the maxilla much shorter than in the other species of the genus, reaching only half the length of the lateral lobe, carpus of pereopod 1 distinctly produced at the base of the claw, propodus broadest at the articulation to the carpus, tapering distally.

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