Human activity and climate variability project: annual report 2002.

This project aims to utilise nuclear techniques to investigate evidence of human activity and climate variability in the Asia Australasian regions. It was originally designed to run over three years, commencing July 1999, with three parallel research tasks: Task 1: Past -- Natural archives of human activity and climate variability; Task 2: Present -- Characterisation of the global atmosphere using radon and fine particles; Task 3: Future -- Climate modelling: evaluation and improvement; Main project objectives -- To determine what proportions of changes in natural archives are due to human activity and climate variability; -- To contribute to the understanding of the impact of human induced and natural aerosols in the East Asian region on climate through analysis and sourcing of fine particles and characterisation of air samples using radon concentrations; -- To contribute to the improvement of land surface parameterisation schemes and investigate the potential to use isotopes to improve global climate models and thus improve our understanding of future climate. Significant project outcomes -- An improved understanding of natural and anthropogenic factors influencing change in our environment; -- A better understanding of the role of aerosols in climate forcing in the Asian region, leading to improved ability to predict climate change; -- An improved understanding of long term changes in the concentrations of trace species in the atmosphere on a regional and a global basis and their use in model evaluation; -- Improved understanding of the impact of different land-surface schemes on simulations by atmospheric models. The next two years of the project Our new and extended projects efforts include: 1) Aligning ourselves with the recently developed mission of the IGBP/PAGES research program 'Human Interactions on Terrestrial Ecosystems' and co-ordinating the Australasian research effort. Further research will focus on: (1) How widespread and reliable are evidence of major climatic events, such as storms and El Nino/La Nina cycles, in natural archives? This would require more natural archives to be examined from northern Australia and also records to be obtained from southern Australia. (2) The spatial extent of mining related pollutants, in the form of aerosol particles, which is of importance to managing the waste in the future. A combination of aerosol and archival studies will address this issue. In Summary: To achieve these extended goals we successfully gained another two years of further support for our project

Rainforest response to glacial terminations before and after human arrival in Lutruwita (Tasmania)

Limited understanding of how Indigenous people have created and managed the Australian landscape continues to have repercussions on how landscapes are culturally interpreted and managed today. Addressing this is critically important as climate change is increasing the frequency and intensity of wildfires, whilst challenging the objectives, methods and efficacy of contemporary landscape management practices. Here we compare the palaeoecology of vegetation changes across glacial to interglacial states before (Termination II) and after (Termination I) human occupation of the cool temperate rainforests of western Lutruwita (Tasmania). Sediment from Darwin Crater (Termination II) and Lake Selina (Termination I) were analysed using radiometric dating, fossil pollen, charcoal, geochemical, environmental magnetic and sedimentary methods to produce a comprehensive reconstruction of vegetation and landscape dynamics. Results show marked differences in the rainforest response to the transition from glacial to interglacial climates before and after human arrival at c. 43,000 years ago (ka). In the absence of human disturbance, Phyllocladus aspleniifolius-Nothofagus cunninghamii lowland rainforest taxa dominated the last interglacial period (∼77% of the pollen sum) but was reduced in the current interglacial (∼41%) and largely replaced by Gymnoschoenus sphaerocephalus buttongrass moorland (10–23%). This demonstrates the legacy of Indigenous Palawa managed landscapes, primarily using fire to promote landscape openness and prevent the dominance of an ecologically climax rainforest community, until their forced removal via invasion and colonisation ca. 1806

Scientific Drilling of Lake Sediments at Darwin Crater, Tasmania

A 70 meters long continental sediment record was recovered at Darwin Crater in western Tasmania, Australia. The new sedimentary archive includes a pre-lake deposit and the complete lake sediment succession accumulated over several glacial/interglacial climate cycles in the ~816 ka meteorite impact crater. A total of 160 meters of overlapping sediment cores were drilled from three closely-spaced holes. Here we report on the drilling operations at Darwin Crater and present the first results from multi-sensor whole core logging, sediment description and multi proxy pilot analysis of core end samples. The multi-proxy dataset includes spectrophotometry, particle size, natural gamma ray, paleo- and rock-magnetism, loss-on-ignition and pollen analyses. The results provide clear signatures for alternating glacial and interglacial sediment facies. The succession returns a minimum of seven inferred glacial cycles. Initial paleomagnetic analysis indicate reversed magnetic polarity in the deepest sediments drilled at Hole B. If geomagnetic in origin, this result constrains the sediment 2.5 m below commencement of lacustrine deposition to an age between ~816 ka and the Matuyama-Brunhes geomagnetic reversal ~773 ka, which is consistent with the interpretation of seven glacial cycles. High-resolution analysis and detailed multi-disciplinary studies are underway with a primary focus on dating, paleomagnetism, and paleoclimate

Retrospectieve monitoring van verzuring en eutrofiering in het Kolkven en Van Esschenven bij Oisterwijk

Een groot deel van de natuurgebieden in Nederland is sterk in kwaliteit achteruitgegaan en genivelleerd als gevolg van atmosferische depositie. Het duurzaam voortbestaan en herstel van de genivelleerde en bedreigde ecosystemen en soorten is op lange termijn slechts mogelijk indien maatregelen worden genomen die de luchtverontreiniging doen afnemen. ln dit kader vormen de Oisterwijkse Vennen een belangrijk onderzoekgebied

Estimating Intermolt Duration in Giant Crabs (Pseudocarcinus gigas)

Estimates of intermolt duration of giant crabs, based on tag-recapture methodology, are used in evaluating management options. However, several short-comings of tag-recovery data have been noted including the low number of tags inserted in legal-sized animals and that the unusually long intermolt duration requires long periods of time-at-large. This need led to the evaluation of alternative methods to estimate intermolt duration. Reproduction in female giant crabs occurs in annual cycles, although females occasionally 'skip' a reproductive season and do not become ovigerous; it has been noted previously that this appears to be associated with molting. Thus the proportion of females that do not participate in reproduction may indicate the proportion molting. We tried this approach with a sample of 342 females and measured the number that were 'skipping' a reproductive season by computerised tomography scanning (CT-scanning) of their ovaries prior to the extrusion of eggs. From the inferred proportion molting intermolt duration was estimated at 9 years for mature size classes, however 95% confidence limits were broad (6.8-13.1 years). This estimate does, however, corroborate those previously reported from studies in which tag and recapture methods were employed. Radiometric ageing (228Th/ 228Ra) of carapaces was also undertaken with the focus of this work on testing an assumption of the method, rather than describing the intermoult duration of a population. We tested the assumption that there is negligible exchange of radionuclides during intermolt in the exoskeleton, which is critical for reliable estimation of intermoult. SEM images of the internal structure of the exoskeleton indicated that exchange of material within the exoskeleton was unlikely and the majority of radiometric assays were consistent with this observation. Radiometric age was estimated by gamma spectroscopy, which allowed rapid analysis compared to previously reported methodology. This rapid processing may facilitate broader application of radiometric ageing to crustacean research

South African cancer bulletin : an official publ. of the National Cancer Association of South Africa

Surface elevation tables, feldspar marker horizons, and210Pb analysis of core profiles were implemented at four sites in Western Port Bay, Victoria, Australia, to provide information on the role of sedimentation, subsidence or compaction, and enhanced sea-level rise in contributing to salt marsh decline. Photogrammetric surveys indicate that the rate of salt marsh decline that is attributable to mangrove encroachment is lower in Western Port Bay than in comparable sites in New South Wales. Differences in the rate of mangrove encroachment at Western Port Bay may be attributed to the inverse relationship found between the degree of mangrove encroachment and surface elevation increase. While sedimentation contributes to surface elevation changes, surface elevation is not solely explained by sedimentation; factors including autocompaction and changes in the water table also play a significant role in Western Port Bay. Historic sedimentation rates measured using210Pb dating techniques corresponded to contemporary sedimentation rates determined from feldspar marker horizons. Core sediment profiles show no change in sedimentation rates at three sites. A fourth site (French Island) was the only site that exhibited high rates of sedimentation, which appears to be related to local land-use changes in the area. All sites maintained their elevation with respect to sea level over the study period. Historic sedimentation exceeded sea-level rise for the past 32 yr, but it is difficult to determine the extent to which belowground processes affect surface elevation, causing deviations between surface elevation and sedimentation over longer periods

Using X-ray fluorescence core scanning to assess acid sulfate soils

During the formation of acid sulfate soils (ASS), several chemical elements in the sediment are mobilised. These elements are removed from the sediment or become enriched as precipitates in distinct horizons. The stratigraphic depth in which these precipitates accumulate is element-specific and is located either within the oxidised or in a transitional zone between the oxidised and the reduced zone. Aim of this study is to demonstrate how X-ray fluorescence core scanning, together with detailed sediment descriptions, can be used to perform an initial assessment of these different zones in ASS in a fast and cost-effective manner. We measured the chemical element signatures of K, Fe, Pb, Sr, Zn, Ni, Y, Mn and Ca in two sediment cores from Western Australia where ASS are suspected to occur. The oxidised zone in both cores is characterised by the occurrence of jarosite, which is indicated by pale straw yellow mottling and synchronous peaks in Fe/Ti, K/Ti, Pb/Ti and Sr/Ti, and of other secondary Fe-oxides, which are indicated by reddish mottling and synchronous peaks in Fe/Ti and Pb/Ti. The transition zone into reduced material is marked by synchronous peaks in Zn/Ti, Ni/Ti, Y/Ti and Mn/Ti. Based on these characteristic signatures, we broadly estimated the depth of the oxidised and the transitional zone at both sites. © 2014, CSIRO

Uranium/thorium dating of Late Pleistocene peat deposits in NW Europe, uranium/thorium isotope systematics and open-system behaviour of peat layers

The possibility of dating peat by the uranium-series disequilibrium method is discussed. In principle, this method can be used to date peat to ~350 ka. The application of the U/Th disequilibrium method (UTD) on peal provides us with the probability of constructing a new chronology for the Late Pleistocene paleoclimatic record in NW Europe. The reliability of the obtained ages will be discussed as well as open-system behaviour and the contamination with detrital Th. By studying in detail interglacial peat profiles from the Tenagi Philippon site, Greece (a long terrestrial record), of an expected age of 125 ka and the Fenit site in Ireland of unknown age, we were able to explain the results in terms of the suspected open-system behaviour of top and bottom parts of these layers and how to avoid it by careful sampling. Peats contaminated with detrital Th were also analysed. Two peat layers, which were interpreted on basis of pollen analyses, stratigraphic position and TL dates to be early Last Glacial in age, were sampled. The first one is the Allt Odhar organic layer near Inverness, Scotland, and gave an age of 106 ka. The second is the key site to the British Last Glacial stratigraphy, the Chelford organic layer at Chelford, Cheshire, yielded an age of 86 ka which is in good agreement with the recently obtained TL dates.