23 research outputs found
A record of late Quaternary environments at lunette-lakes Bolac and Turangmoroke, Western Victoria, Australia, based on pollen and a range of non-pollen palynomorphs
No full textA palaeoecological record from Lakes Bolac and Turangmoroke details the changing nature of vegetation patterns, lake levels and climate in the drier part of the Victorian Western Plains over approximately the last 90,000 years. In addition to the routine palynological proxies of pollen, spores and charcoal, a range of non-pollen palynomorphs (remains of algae, fungi, insects and other invertebrates) was analysed and described and provides useful additional information on the ecology of past vegetation communities. A chronology for the record is provided by radiocarbon and refined optical luminescence dating in the upper part of the sequence, and the latter technique is used to provide a timeframe for the period beyond the radiocarbon limit. The record shows that during marine isotope stage (MIS) 5.1 and mid MIS 3 the regional vegetation was composed of open woodland dominated by Allocasuarina luehmannii type with low numbers of Banksia, Eucalyptus and other Myrtaceae under which a diverse understorey developed. During these times Lake Turangmoroke held fresh water of varying depths. The degree of representation of MIS 4 and MIS 3 in the record is uncertain owing to discontinuities resulting from the lake having periodically dried. A change to open grassland-steppe occurred shortly after 47,000 years ago and lake levels fluctuated considerably before the lake became shallow and saline. Open grassland-steppe continued through MIS 2 with almost no trees present while the aquatic flora reflected further lake level declines and increasing salinity. Driest conditions, indicated by deflation of lake sediments during lunette building, occurred between similar to 18,000 and similar to 11,000 cal yr BP. Open woodland in the early Holocene was dominated by A. verticillata type until partial replacement by Eucalyptus around 7000-8000 (14)C yr BP when the vegetation cover present at European arrival was established. (c) 2008 Elsevier B.V. All rights reserved
Observed relationships between El Niño-Southern Oscillation, rainfall variability and vegetation and fire history on Halmahera, Maluku, Indonesia
No full textA temporally high-resolution palynological study of the uppermost section of core MD98-2180 from Kau Bay, Halmahera, Indonesia, provides a vegetation and fire record covering the last 250 years. The record is compared with the Maluku Rainfall Index, Southern Oscillation Index (SOI) and southern hemisphere winter sea surface temperatures (SST) for the central Pacific Ocean based on instrumental data, as well as reconstructions of the SOI and the central Pacific SST and historically recorded El Nino events. The results show that significant El Nino events are generally associated with increased representation of Dipterocarpaceae pollen, probably reflecting the mass-flowering of this taxon during El Nino-Southern Oscillation (ENSO) droughts, and elevated charcoal levels, reflecting a greater incidence of fires during these extremely dry periods, while humid phases show increased fern numbers. Our findings demonstrate that pollen records 'ecological' in scale can provide useful additional proxy records of ENSO events
The influence of the 73 ka Toba super-eruption on the ecosystems of northern Sumatra as recorded in marine core BAR94-25
No full textExamination of pollen content and geochemical analysis of marine core BAR94-25 taken from ~100 km north-west of Sumatra in the Andaman Sea reveals a ~100,000 year record of environmental change as well as the influence of the Toba super-eruption at ~73,000 years ago on the ecosystems of northern Sumatra. The record also contains an older volcanic ash dated to ~89,000 years ago, allowing a comparison of the effects of two eruptions on the local environments of the island. The immediate effects of the older eruption on the ecosystem of northern Sumatra were limited, though a gradual and substantial increase in pine forest likely followed the event in the longer term. The Toba super-eruption at ~73,000 years ago, however, had an instantaneous and devastating effect on the pine forests of northern Sumatra. Evidence for impacts of this super-eruption at ~73,000 years ago on regional climatic conditions remains inconclusive. Climatic changes inferred from the pollen record or estimated via pollen transfer functions date to a few thousand years after the eruption, or are clearly linked to long-term climatic trends initiated a few thousand years before. © 2011 Elsevier Ltd and INQUA.Sander van der Kaars, Martin A.J. Williams, Franck Bassinot, François Guichard, Eva Moreno, Fabien Dewilde, Ellyn J. Coo
Development and testing of transfer functions for generating quantitative climatic estimates from Australian pollen data
No full textGlacial and deglacial climatic patterns in Australia and surrounding regions from 35 000 to 10 000 years ago reconstructed from terrestrial and near-shore proxy data
No full textCopyright © 2009 Elsevier Ltd All rights reserved.This study forms part of a wider investigation of late Quaternary environments in the Southern Hemisphere. We here review the terrestrial and near-shore proxy data from Australia, Indonesia, Papua New Guinea (PNG), New Zealand and surrounding oceans during 35-10 ka, an interval spanning the lead-up to the Last Glacial Maximum (LGM), the LGM proper (21 ± 2 ka), and the ensuing deglaciation. Sites selected for detailed discussion have a continuous or near continuous sedimentary record for this time interval, a stratigraphically consistent chronology, and one or more sources of proxy climatic data. Tropical Australia, Indonesia and PNG had LGM mean annual temperatures 3-7 °C below present values and summer precipitation reduced by at least 30%, consistent with a weaker summer monsoon and a northward displacement of the Intertropical Convergence Zone. The summer monsoon was re-established in northwest Australia by 14 ka. Precipitation in northeast Australia was reduced to less than 50% of present values until warmer and wetter conditions resumed at 17-16 ka, followed by a second warmer, wetter phase at 15-14 ka. LGM temperatures were up to 8 °C lower than today in mainland southeast Australia and up to 4 °C cooler in Tasmania. Winter rainfall was much reduced throughout much of southern Australia although periodic extreme flood events are evident in the fluvial record. Glacial advances in southeast Australia are dated to 32 ± 2.5, 19.1 ± 1.6 and 16.8 ± 1.4 ka, with periglacial activity concentrated towards 23-16 ka. Deglaciation was rapid in the Snowy Mountains, which were ice-free by 15.8 ka. Minimum effective precipitation in southern Australia was from 14 to 12 ka. In New Zealand the glacial advances date to ∼28, 21.5 and 19 ka, with the onset of major cooling at ∼28 ka, or well before the LGM. There is no convincing evidence for a Younger Dryas cooling event in or around New Zealand, but there are signs of the Antarctic Cold Reversal in and around New Zealand and off southern Australia. There remain unresolved discrepancies between the climates inferred from pollen and those inferred from the beetle and chironomid fauna at a number of New Zealand sites. One explanation may be that pollen provides a generalised regional climatic signal in contrast to the finer local resolution offered by beetles and chironomids. Sea surface temperatures (SSTs) were up to 5 °C cooler during the LGM with rapid warming after 20 ka to attain present values by 15 ka. The increase in summer monsoonal precipitation at or before 15 ka reflects higher insolation, warmer SSTs and steeper thermal gradients between land and sea. The postglacial increase in winter rainfall in southern Australia is probably related to the southward displacement of the westerlies as SSTs around Antarctica became warmer and the winter pack ice and Antarctic Convergence Zone retreated to the south. © 2009 Elsevier Ltd. All rights reserved.Martin Williams, Ellyn Cook, Sander van der Kaars, Tim Barrows, Jamie Shulmeister and Peter Kersha
Attention-deficit/hyperactivity disorder: a systems perspective. A comprehensive qualitative analysis of the literature
No full textPlan BAttention-Deficit/Hyperactivity Disorder (ADHD) is a neurological syndrome resulting in problems with self-regulation. ADHD is characterized by inattention and/or hyperactivity-impulsivity which causes impairment in at least two settings. These characteristics often arise in childhood and were previously thought to diminish during adolescence and disappear by adulthood. However, studies over the past decade indicate that although some symptoms may decrease in severity, ADHD does continue throughout adulthood for many individuals. The impact of this disorder is felt not only by the individuals with ADHD, but also by the various systems in which these individuals live, work, and socialize. In this comprehensive analysis of the literature ADHD is discussed from a systemic perspective. Initially the symptoms and characteristics that define ADHD are reviewed along with other disorders that commonly coexist with ADHD, and what research tells us does and does not cause ADHD and the development of the co-morbid disorders. Prevalence of ADHD and co-morbidity is also reviewed. The term “system” is defined and the various systems presented as related to this topic, from the micro-system of the individual to the macro-system of society at large. As the characteristics of ADHD are exhibited inconsistently according to the age of the individual and the context of the interaction, these are addressed, as appropriate, in the categories of child, adolescent/teen, and adult for each system. The first system discussed is the internal system of the individual in which ADHD resides. This micro-system consists of the biological, intellectual, and psychological components. This is followed by examination of this micro-system of the individual interacting in the family system, both nuclear and extended. The common effects on other family members in the system and the system as a whole are discussed. With understanding of the individual and his/her family with ADHD as a foundation, the view is broadened to other systems in which both the individual and his/her family operate. The discussion includes the reciprocal effects of ADHD and the educational, employment, social/recreational, and legal systems, as well as the influence of interactions between these systems. The presentation of the pervasive impact of ADHD on all systems is followed by analysis of the different treatment options and effectiveness. Included are interventions in the areas of interpersonal relationships within the family, social relationships, leisure/recreation, school, work, and in the legal arena. Since the acceptance and attitude about ADHD are important factors in interaction and treatment effectiveness, these are also investigated throughout. A summary of the analysis of the literature is presented in the second chapter. This is followed by conclusions and a discussion of implications for marriage and family therapists
Latest Pleistocene and Holocene vegetation and environmental history of the Western Plains of Victoria, Australia
No full textVolume: 116Start Page: 139End Page: 16
Stable isotopes and Mg/Ca ratios of planktonic foraminiferal species (G. truncatulinoides, O. universa, G. ruber) from sediment core MD03-2416G
No full textProxy parameter of core MD03-2614G: Isotope-geochemical were performed on the planktonic foraminiferal species Globorotalia truncatulinoides, Orbulina universa and Globigerinoides ruber. The foraminiferal specimens were selected from sediment core MD03-2614G, which was recovered from south of Cape Pasley (south of Australia; 34°43.73S 123°25.70E) from 1070 m water depth during R/V Marion Dufresne Cruise MD131 in 2003 (https://doi.org/10.17600/3200090). Sampling and analytical studies were carried out from ~2 to 538 cm core depth at 2 cm spatial resolution. The records cover the last ~60 kyrs. The stable carbon (δ13C; ‰ VPDB) and oxygen isotope (δ18O, ‰ VPDB) analyses were performed on a Thermo Scientific MAT 253 mass spectrometer with an automated Kiel IV Carbonate Preparation Device. The proxy data provide stratigraphical information and were used to calculate the ice volume-corrected δ18O of seawater (δ18Osw-ivc; ‰ VSMOW). The geochemical analyses were performed on a VARIAN 720–ES Axial ICP-OES, a simultaneous, axial-viewing inductively coupled plasma optical emission spectrometer coupled to a VARIAN SP3 sample preparation system at GEOMAR. G. truncatulinoides were analyzed on a simultaneous, radially viewing ICP-OES (Ciros CCD SOP, Spectro A.I., Univ. Kiel). Sample introduction was performed via an autosampler (Spectra A.I.). Mg/Ca ratios (mmol/mol) were converted into thermocline (TT; °C) and sea surface temperatures (STT; °C). Contaminant phases are added: Al/Ca, Fe/Ca, Mn/Ca in mmol/mol)
Mixing in a coastal environment : 1. A view from dye dispersion
No full textAuthor Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C10013, doi:10.1029/2003JC002194.Dye release experiments were performed together with microstructure profiling to compare the two methods of estimating diapycnal diffusivity during summer and fall stratification on the continental shelf south of New England. The experiments were done in 1996 and 1997 as part of the Coastal Mixing and Optics Experiment. During the 100 hours or so of the experiments the area of the dye patches grew from less than 1 km2 to more than 50 km2 [ Sundermeyer and Ledwell, 2001 ]. Diapycnal diffusivities inferred from dye dispersion range from 10−6 to 10−5 m2/s at buoyancy frequencies from 9 to 28 cycles/hour. Diffusivities estimated from the dye and those estimated from dissipation rates in the companion paper by Oakey and Greenan [2004] agree closely in most cases. Estimates of diffusivities from towed conductivity microstructure measurements made during the cruises by Duda and Rehmann [2002] and Rehmann and Duda [2000] are fairly consistent with the dye diffusivities. The dye diffusivities would be predicted well by an empirical formula involving shear and stratification statistics developed by MacKinnon and Gregg [2003] from profiling microstructure measurements obtained at the same site in August 1996. All of the measurements support the general conclusion that the diffusivity, averaged over several days, is seldom greater than 10−5 m2/s in the stratified waters at the site, and usually not much greater than 10−6 m2/s. Severe storms, such as a hurricane that passed over the CMO site in 1996, can dramatically increase the mixing at the site, however.This work was part of the ONR Coastal
Mixing and Optics Experiment, and was funded by grants N00014-95-1-
0633, N00014-95-1-1063, N00014-95-1-1064, and N00014-01-1-0211.
Completion of this paper was supported by the Edward W. and Ellyn B.
Scripps Chair awarded to J. Ledwell. H. Seim’s participation was supported
by ONR grant N00014-96-1-0616
