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Hypersaline spring water (TDS ∼ 85 g/L) and gas are escaping from the top of a calcite travertine mound on Anticosti Island. This mound is located in the Chaloupe River area above the Jupiter Fault which cuts through the Ordovician formations in the subsurface, including the oil and gas-rich Macasty Shale Formation. The Cl content is approximately 3 times that of seawater, but the geochemical profile indicates it to be a Paleozoic basin brine (geogenic He = 2E–7 cc/cc) evaporatively enriched beyond halite saturation (Br:Cl molar ratio = 0.0022 ± 0.00013) that has been diluted by some 73 ± 6% with meteoric waters. Measurable tritium (3.4 TU) indicates this to be a mixture of modern and Holocene recharge. The radioiodine (129I < 10 million atoms/L) is a three-component mixture of geogenic and post-nuclear contributions with low levels in pre-nuclear Holocene recharge. Degassing at the vent (1% to 2% CO2, PCO2 = 0.02 atm, >90% CH4) provokes calcite precipitation and travertine mound formation. Methane comprises a thermo-catalytic component and a biogenic component produced at depth in the organic-rich Macasty Formation by reduction of surface-derived dissolved inorganic carbon (DIC; a14C = 3.5 pMC), producing enriched δ13CDIC values recorded in the travertine. The occurrence of basin-derived brine and gas discharging in association with the surface expression of the Jupiter fault implies that this fault provides a pathway for deep circulation of meteoric waters, likely driven by the relief on the island. [ABSTRACT FROM AUTHOR]

The use of fire as an offensive and defensive weapon on the colonial frontier in Australia has received little scholarly attention. This article aims to build on insights from current historiography about the customary use of fire by Aboriginal peoples within the borders of Victoria, Australia. Specifically, our aim is to highlight the historically significant role Aboriginal peoples' use of fire played in resisting the colonists in Victoria during the colonial period. By closely scrutinising documentary records it is possible to demonstrate that Aboriginal people used fire, both offensively and defensively, against the colonists. [ABSTRACT FROM AUTHOR]

Regional geochemical characterization of groundwaters in a bedrock aquifer in the Ottawa – St. Lawrence Lowlands of eastern Ontario has identified an iodine (I) anomaly, with values regularly exceeding 150 μg/L and a maximum observed concentration of 10 812 μg/L. The spatial distribution, enrichment mechanisms, and sources of I and organic matter were investigated using geochemical and isotopic data. High-I groundwaters (>150 μg/L) are prevalent in Na–Cl-type groundwaters at low bedrock elevations in areas overlain by thick layers of glacial sediments. I is thought to be linked to massive muds in the glacial sediments overlying the aquifer, deposited during the postglacial incursion of the Champlain Sea 12–10 ka BP. Principal component analysis of I and 18 other chemical parameters revealed correlations among I, salinity, and indicators of microbial oxidation of organic matter, suggesting that the intrusion of saline pore waters affected by decomposition of organic matter such as marine phytoplankton in the massive muds is the dominant process controlling I enrichment in groundwater. 129I/127I ratios in the pre-modern waters vary between near-marine values of 460 × 10−14 and 5 × 10−14, demonstrating that older allochthonous I derived from the surrounding Paleozoic sedimentary terrain also contributed to the I pool in the Champlain Sea basin. 14C ages and δ13C signatures for dissolved organic carbon in groundwater and disseminated organic carbon within the glaciomarine muds highlight an allochthonous source of terrestrial organic carbon predating the Champlain Sea incursion, likely transported via glacial meltwaters in tandem with I to the Champlain Sea basin. [ABSTRACT FROM AUTHOR]

Controlled tile drainage (CTD) is an agricultural management practice with well-documented water quality and agronomic benefits. However, due to field water drainage abatement effects, the practice could potentially impact soil respiration. The δ 13 C of soil gas samples were analyzed from silt loam CTD and uncontrolled tile drained (UTD) fields cropped with corn, soybean, and forage to test whether CTD affects total soil respiration (R T ) through altering residue decomposition and/or gas transport. We also examined whether CTD imparted an over tile (OT) and between tile (BT) locational effect on R T . All gas samples are from bulk rhizosphere and microbial sources; except for the forage crop measurements which included plants growing inside the sampling chamber collars. The mean values of δ 13 C for R T were not statistically different ( p > 0.05) between four of the five CTD and UTD field pairs. Neither were the means of δ 13 C of R T different ( p > 0.05) between OT and BT locations in four of the five CTD fields. The generalized lack of statistical differences in δ 13 C of R T observed, may have resulted from the drier and wetter seasonal conditions muting drainage management effects on surface soil water contents. The results could be used to help refine the carbon footprint of tile drainage management practices. [ABSTRACT FROM AUTHOR]

Drill cores collected from an 860-m-thick Paleozoic (Cambrian to Devonian) sedimentary sequence of the Michigan Basin in southwest Ontario, Canada, were used to develop vertical profiles of natural tracers in porewater from the sedimentary sequence and build a conceptual model regarding processes and timing of solute migration. In this paper, the conceptual model is quantitatively assessed with numerical simulations of diffusion-dominated solute transport (Cl − and 18 O). The conceptual model suggests that the tracer profiles result from mixing between a deep shield brine with isotopic characteristics consistent with water–rock interaction over a long period of geologic time, Ordovician seawater at intermediate depth, and an overlying hypersaline brine formed by evaporation of seawater in a restricted basin during the Silurian. Between the peak of basin consolidation at 300 Ma BP and the Pleistocene (2.6 Ma BP), salinity and isotopic concentration gradients are thought to have driven mixing, dominantly by diffusion. Water isotope data indicate that in the Pleistocene, melt water infiltrated to a maximum depth of 330 m in the Silurian Salina Formation, likely in response to transient glacial loading and elevated sub-glacial hydraulic pressures. Also in the Pleistocene, over-pressured conditions in deep regions of the basin drove high-salinity brine eastward in the basal Cambrian aquifer, interrupting pre-existing tracer-diffusion profiles. A base case set of boundary and initial conditions provides a good fit between simulated and measured tracer profiles, but requires effective diffusion coefficients ( D e ) in the Ordovician limestones that are lower than the average values obtained in laboratory measurements by as much as a factor of 10. The base-case values are still within the overall range of measured values. At the formation scale, relatively low in-situ D e values are attributed to the intermittent occurrence of gas and liquid hydrocarbons in the Ordovician carbonate units and the effect of lithostatic confining pressure; neither of which are accounted for in the laboratory measurements but both would have the effect of decreasing D e for aqueous solutes. The numerical model is most sensitive to the formation-specific D e values and geologically reasonable variations in initial and boundary conditions have a relatively small influence on the results. Additional simulations indicate that hydraulic disturbance and ingress of meltwater during the Pleistocene can explain second-order features observed in the measured tracer profiles. This work provides supporting evidence for previous research indicating that the porewater residence time in the Ordovician sequence approaches the age of the rocks. [ABSTRACT FROM AUTHOR]

This paper concerns the question of why there are so few named groups in the Woiwurrung language area compared with other language groups to its west and north-west. It does this by analysing the 1863 Governor's levee in which representatives from three Aboriginal groups -- the Boonwurrung, Woiwurrung and Tara-Waragal -- presented gifts to royalty. In seeking to understand who this third group -- the Tara-Waragal -- was, Stephens (2003) has suggested that they were a Woiwurrung patriline. Wesson (2001) has suggested that the name was a pejorative label applied to a Gippsland group by the Kulin. This study finds that both interpretations are wrong. First, it finds that the name applies to a Brataualung clan, the Yowung, whose country centred on the Tarra and Warrigal creeks -- hence the name. Second, it finds that the attempt by Stephens to identify the Tara-Waragal with a possible Woiwurrung patriline identified in a series of sketches by William Thomas found in the RB Smyth Papers was also a failure. Nevertheless, the implication that the sketch maps may reveal up to 53 patrilines is a possibility worth exploring, as it may address the issue of the apparent under-representation of Woiwurrung named groups with which I began. Analysis reveals the possibility of an additional 27 Woiwurrung patrilines. Although the exact number of additional patrilines will never be known, at least we have addressed the issue that within the ethno-historical record it is possible to find additional named groups in Woiwurrung. Thus there was in all likelihood greater internal division in the Woiwurrung than has been reconstructed by Barwick (1984) and Clark (1990). [ABSTRACT FROM AUTHOR]

Abstract: Radioiodine, 129I is a biophilic and mobile radionuclide, and a major contaminant of concern for long term radioactive waste disposal. Nuclear fuel reprocessing has released large amounts of anthropogenic 129I in a number of locations globally; this has led to an increase in the concentration of 129I and the 129I/127I ratio in the environment. Therefore, a detailed understanding of its movement and concentration in the environment is essential. While 129I dispersion has been examined in the vicinity of nuclear activities, little is known about its accumulation in remote regions. Accordingly, we have undertaken reconnaissance sampling in the Arctic as a location that may be affected by 129I fallout. Samples from large watersheds were collected in northern Canada on a trajectory starting in Whitehorse, Yukon Territory (60°43′00″N) and moving north to Tsiigehtchic, Northwest Territory (67°26′26″N). Results show concentrations of 129I up to 27×106 atoms/L are present in Northwest Canada and 129I/I ratios up to 1.68×10−10. Annual 129I fallout ranges from 2.78×109 to 7.95×109 atoms/m2/yr, calculated by normalizing the measured values to watershed area and discharge. These quantities substantially exceed literature values for waters containing only geogenic or cosmogenic production and are similar for all watersheds regardless of watershed area or discharge. Anthropogenic releases of 129I into the atmosphere or oceans are the major potential sources of 129I in the Arctic. [Copyright &y& Elsevier]

This paper offers a fundamental critique and re-evaluation of the historical sources and more recent reconstructions which have been used to determine the language area of the Birrdhawal people of far eastern Victoria. In relation to Birrdhawal tribal territory, this paper addresses three critical issues: first, whether the Birrdhawal language is related to the Ganai language, is part of the Yuin language cluster or is a standalone distinct language; second, whether or not their country included any coastline or was landlocked; and, third, whether or not any of their country was subsumed into that of the Krauatungalung through land succession as argued by Wesson (1994, 2000, 2002). The paper offers a comparative and quantitative analysis of vocabulary from the study area and critiques previous research into constituent local group organisation. [ABSTRACT FROM AUTHOR]

This paper is concerned with the Coranderrk Aboriginal artist Timothy Korkanoon. Research has uncovered more about his life before he settled at the Coranderrk station in 1863. Evidence is provided that five sketches acquired by George Augustus Robinson, the former Chief Protector of Aborigines, in November 1851 in Melbourne, and found in his papers in the State Library of New South Wales, may also be attributed to the work of the young Korkanoon when he was a student at the Merri Creek Baptist Aboriginal School from 1846 to 1847. [ABSTRACT FROM AUTHOR]

Abstract: The molar ratios of atmospheric gases change during dissolution in water due to differences in their relative solubilities. We exploited this characteristic to develop a tool to clarify the origin of ice formations in permafrost regions. Extracted from ice, molar gas ratios can distinguish buried glacier ice from intrasedimental ground ice formed by freezing groundwaters. An extraction line was built to isolate gases from ice by melting and trapping with liquid He, followed by analysis of N2, O2,, Ar, 18OO2 and 15NN2, by continuous flow mass spectrometry. The method was tested using glacier ice, aufeis ice (river icing) and intrasedimental ground ice from sites in the Canadian Arctic. O2/Ar and N2/Ar ratios clearly distinguish between atmospheric gas in glacial ice and gases from intrasedimental ground ice, which are exsolved from freezing water. δ 15NN2 and δ 18OO2 in glacier ice, aufeis ice and intrasedimental ground ice do not show clear distinguishing trends as they are affected by various physical processes during formation such as gravitational settling, excess air addition, mixing with snow pack, and respiration. [Copyright &y& Elsevier]

Ontario's recent Postsecondary Review, led by former premier Bob Rae, was dramatically more successful than previous reviews by special-purpose advisory commissions on postsecondary education conducted in Ontario. The authors argue that the success of special-purpose advisory commissions — defined as the extent to which a commission's recommendations are implemented in a timely way — is dependent on environmental variables (such as the economy, fiscal situation and political cycle), process variables (such as reporting relationships, characteristics of the commissioners and stakeholder strategies) and the political acuity with which the commission develops recommendations that can command broad public support. The Rae review benefited from political conditions that favoured stronger investments in postsecondary education, despite, a difficult fiscal situation. The report also benefited from a stakeholder community that was able to put aside most internal differences for the sake of a perceived common good. Within this environment, the review created a highly focused process that involved extensive consultation, the support of expert panel members and frequent interaction with decision-makers. The review developed recommendations that were sensitive to long-standing patterns of public opinion, articulated new public goals, recognized the important role to be played by each major stakeholder and proposed a new institution to entrench positive change in the long term. This experience offers lessons for governments, stakeholders and future commissions on how to manage special-purpose advisory commissions in a way that maximizes their Policy impact. [ABSTRACT FROM AUTHOR]

This article examines the evidence for land succession in western Victoria and considers the fission, fusion, and extinction of some clan groups at the time of contact with non-Aboriginal people in the late 1830s and 1840s. A special study is made of the intriguing scraps of evidence surrounding Knenknenwurrung. This appears to be the case of a cluster of related clans fragmenting and being absorbed into contiguous language groups--some into Djadjawummg, some Jardwadjali, and the majority absorbed into Djabwoirrung. Exactly when this fragmentation and fission occurred is unclear, but certainly within the living memory of Aboriginal people in the early 1840s. [ABSTRACT FROM AUTHOR]

The authors believe that management reform initiatives can be jeopardized by the government-wide application of idealized management frameworks. They suggest that, according to what they call "the law of mandated utopias," the resultant management requirements become surreal in the eyes of departmental managers. The authors explore the ethical and practical dilemmas caused by the conflict between a public servant's duty to comply with centrally imposed requirements and the duty to manage people and public monies in a sensible way. The recent management improvement initiatives in the Government of Canada are used to demonstrate the practical limitations of the conceptual frameworks associated with performance measurement, performance audit, modem comptrollership, and human resources development. Suggestions are offered on how to improve management in departments while dealing with the surreal requirements generated by government-wide reforms based on utopian frameworks. [ABSTRACT FROM AUTHOR]

Hypersaline brines of marine origin, deep within fractured crystalline rocks of the Canadian Shield, are characterized by calcium-chloride compositions with relatively low concentrations of magnesium and sulphate. Such chemistries among crustal fluids are very unusual, regardless of their origins, which makes it difficult to identify possible genetic associations between shield brines and other marine brines. Key conservative chemical and isotopic attributes of shield brines from the Yellowknife and Sudbury areas are similar, however, to those of fluid inclusions in sparry, late-stage hydrothermal dolomites in lower Paleozoic carbonates of the Western Canada Sedimentary Basin, suggesting that both fluid types originated from a residual seawater brine of probable Devonian age. This interpretation is supported by determination of a helium-4 model age for the Yellowknife brine that is consistent with a Devonian origin. Therefore, dolomitization was likely both a major source of Ca and a sink for about half of the initial Mg in the brine prior to its infiltration into the underlying basement rocks. Mass-balance considerations indicate that albitization of plagioclase, predominantly in basinal clastic sediments, was an equally important mineral source of Ca to the infiltrating brine, but interactions with carbonate and silicate rocks cannot account for the entire Ca inventory in the brine. A major contribution to the Ca budget must also have been initially provided by the evaporative concentration of seawater, which is only possible if it were enriched in calcium and depleted in sulphate compared with modern seawater, as was probably the case during Devonian time. [ABSTRACT FROM AUTHOR]

Recovery of gold from arsenopyrite-hosted ore in the Giant Mine camp, Yellowknife, NWT, Canada, has left a legacy of arsenic contamination that poses challenges for mine closure planning. Seepage from underground chambers storing some 237,000 tonnes of arsenic trioxide dust, has As concentrations exceeding 4000 ppm. Other potential sources and sinks of As also exist. Sources and movement of water and arsenic are traced using the isotopes of water and sulphate. Mine waters (16 ppm As; As V /As III ≈ 150) are a mixture of two principal water sources - locally recharged, low As groundwaters (0.5 ppm As) and Great Slave Lake (GSL; 0.004 ppm As) water, formerly used in ore processing and discharged to the northwest tailings impoundment (NWTP). Mass balance with δ 18 O shows that recirculation of NWTP water to the underground through faults and unsealed drillholes contributes about 60% of the mine water. ;[emsp]>Sulphate serves to trace direct infiltration to the As 2 O 3 chambers. Sulphate in local, low As groundwaters (0.3-0.6 ppm As; δ 34 S SO 4 ∼ 4 ‰ and δ 18 O SO 4 ∼ - 10 ‰) originates from low-temperature aqueous oxidation of sulphide-rich waste rock. The high As waters gain a component of 18 O-enriched sulphate derived from roaster gases (δ 18 O SO 4 = + 3.5 ‰), consistent with their arsenic source from the As 2 O 3 chambers. High arsenic in NWTP water (∼ 8 ppm As; δ 18 O SO 4 = - 2 ‰) derived from mine water, is attenuated to close to 1 ppm during infiltration back to the underground, probably by oxidation and sorption by ferrihydrite. [ABSTRACT FROM AUTHOR]

Hypersaline Ca/Cl brines of marine origin deep within the crystalline rocks of the Canadian Shield are typically highly depleted in potassium and boron compared to their concentrated seawater parent brine. While this depletion in both solutes is not accompanied by a major alteration in their original marine B/K ratios, their initial marine δ11B has been lowered to 20–30‰, values that are intermediate between that of present day seawater (39‰) and typical crustal values (−3±5‰). Together, these observations eliminate 3 of 4 potential K and B removal mechanisms that may have operated at various times over the long history of shield brines: (1) co-precipitation in late stage evaporative salts in the marine basin where the brine was formed, (2) incorporation in secondary feldspars formed either within basin sediments or the host rocks, and (3) in situ adsorption by secondary clay minerals on fracture surfaces. Rather the δ11B values, together with the consistency in the depleted but similar K/Br and B/Br ratios, suggest that K and B were removed from shield brines by fixation in illitic clay minerals. This likely occurred during the diagenetic illitization of smectite in argillaceous marine sediments through which the brine infiltrated prior to penetrating the underlying crystalline basement rocks. [Copyright &y& Elsevier]

Comments on the article 'The challenge of change: Canadian universities in the twenty-first century,' by David M. Cameron, which appeared in the 'Canadian Public Administration' journal. Nature and extent of the challenge of change at Canada's universities; Validity of the assertion that universities have been slow to adapt and become more entrepreneurial; Universal perspective on provincial funding.

Presents a study which characterized the origin of ground water inflows and mixing in the Canadian Shield. Occurrence of glacial melt water in the Shield; Distribution of salinity and isotonic composition of ground water; Glacial melt water endmember; Mechanism of glacial melt water recharge; Conclusions.

Surficial CO 2 efflux surveys have been used to delineate hydrocarbon source zones in contaminated aquifers and provide estimates of hydrocarbon biodegradation rates. This approach requires distinguishing between CO 2 derived from petroleum degradation and CO 2 produced from natural soil respiration. To this end, radiocarbon has been used to differentiate between 14C–depleted CO 2 from hydrocarbon degradation and 14C–enriched CO 2 from natural soil respiration to effectively quantify the contribution of each source to total CO 2 efflux, and by deduction natural source zone depletion (NSZD) rates. In this study, a systematic method comparison has been conducted to evaluate available approaches for collecting CO 2 gas samples for radiocarbon analysis used to correct total CO 2 efflux measurements for quantifying natural source zone depletion rates. Gas samples for radiocarbon analysis were sampled from (i) dynamic closed chambers (located at ground surface), (ii) static chambers (also at ground surface), (iii) shallow soil gas probes (0.3 m bgs), and (iv) soil gas monitoring wells (~0.6 m below ground surface) during a CO 2 efflux survey conducted at the site of a historical pipeline rupture near Bemidji, MN. The mean fraction of radiocarbon (F14C) obtained from samples overlying the source zone were (i) 0.93 ± 0.01, (ii) 0.73 ± 0.03, (iii) 0.71 ± 0.04, and (iv) 0.41 ± 0.06, for the four methods respectively. These F14C values were used to apportion total CO 2 efflux measurements into contributions of contaminant–derived CO 2 efflux and natural soil respiration to evaluate natural source zone depletion processes. Results suggest that the method of radiocarbon sampling has a significant effect on the calculated fraction of the CO 2 efflux originating from contaminant-related soil respiration, with contributions ranging between 27% and 59% of total soil respiration. Results indicate that radiocarbon sampled from static chambers and shallow soil gas probes methods offer the best compromise between CO 2 sample yield and sample representativeness, providing the most reliable estimates of CO 2 effluxes originating from contaminant degradation. However, the results also show that for this study, all methods agree within a factor of <2.3 regarding the inferred NSZD rates. • Carbon dioxide efflux monitoring for natural source zone depletion • Radiocarbon methods for apportioning contaminant soil respiration • Estimating hydrocarbon source zone biodegradation rates • Dynamic closed chamber, static chamber, soil gas probe and soil gas monitoring well methods for monitoring petroleum hydrocarbon source zones [ABSTRACT FROM AUTHOR]

Presents information on a study on a temporal monitoring of environmental isotopes and geochemistry in ground water within the Raisin River basin, an agricultural watershed in eastern Ontario, Canada. Field sampling and analytical methods; Precipitation and runoff during study period; Seasonal variations in Carbonated geochemistry.

The sulfhydryl-selective fluorescent reagent acrylodan (6-acryloyl-2-dimethylaminonaphthalene) was used to label tropomyosins from rabbit cardiac muscle and from equine platelets. Addition of bovine pancreatic deoxyribonuclease Ito solutions of acrylodan-modified tropomyosins significantly altered the emission properties of the samples. Muscle and non-muscle tropomyosin fluorescence were affected in qualitatively similar manners; emission maxima were red-shifted by about 8 nm to 522-525 nm and maximal intensities were reduced by approximately 15%. Addition of KI to each of the fluorescent samples caused a greater degree of fluorescence quenching in the presence of DNase I than in its absence. The slopes of Stern-Volmer plots were 15-25% steeper in the presence of DNase I. Fluorescence polarization values for acrylodan-labelled tropomyosin samples were 25-35% lower in the presence of DNase 1. Each of these effects could be saturated by addition of about a two- fold molar excess of DNase I to tropomyosin. Together they suggest that interaction with DNase I causes localized unfolding of tropomyosin, thereby allowing the fluorescent label to become more exposed to the solvent and less restricted in its local motions. Circular dichroism measurements support this idea. Addition of DNase I to solutions of either labelled or unlabelled tropomyosin results in a net 14-18% loss in ellipticity near 220 nm, indicative of unfolding of α-helix. [ABSTRACT FROM AUTHOR]

Discusses global economic trends and pressures on government, with regards to Canada and the United States. Categories which global pressures on governments are reviewed; Descriptions of the categories; Implication of global pressures for Canadian governments.

Identifies the main differences between the decision-making environments of the International Monetary Fund (IMF) and Canadian governments. International character and need to solve collaboration problems as basis of decision-making in the IMF; Lessons for Canadian governments from IMF administrative practices.

Focuses on the Public Service 2000 program and the June 1993 government reorganization of Canada. Impact on the centrally driven initiatives to improve the management and productivity of the federal public service; Assessment of the work of the Treasury Board Secretariat during the implementation of the program; Problems faced by the Public Service 2000 program; Policy recommendation.

Presents several letters to the editor concerning health in Great Britain. View of the general practitioners on prehospital thrombolysis; Benefits of physical activity for cardiovascular disease and functional ability of elderly people; Role of alcohol on post-traumatic stress disorder.

An introduction to the journal is presented in which the editor discusses various reports in the issue on the topics including the research on fluids and gases in aquitards, the need for nuclear agencies to find sites for deep geological repositories and the development of oil and gas reserves.

The principal purpose of this study was to gain a greater understanding of the utilitarian and symbolic significance of koalas for Aboriginal communities in Queensland, Australia as recorded by colonists during the early period of colonization and the early twentieth century. It does this primarily through a close examination of the nineteenth-century and early twentieth-century archival records and contemporary publications that relate to Queensland Aboriginal peoples' associations with koalas. This paper is the third in a series investigating the historic and cultural importance of the koala according to the location in Australia. It likewise employs the historical method approach, which relies on identifying historical sources, evaluating their relative authority, and combining their testimony appropriately in order to construct an accurate and reliable picture of past events and environments. Through a critique of the published historical sources, the distribution of and the etymology of "koala" are briefly discussed before an examination is made of the animal's spiritual importance, associated cultural traditions, and simultaneous utilitarian role. Mirroring previous studies published by the authors on Victoria and New South Wales, we confirm that the predominately non-Aboriginal historical records reveal that koalas were hunted for food and their skin in some Queensland regions. It shall be seen that the ethno-historical records are inconclusive about the koala's distribution in Queensland, whether they were hunted across all of the state at the point of colonization and whether they were considered an integral food source in some regions. Furthermore, this study demonstrates that the extent to which they were used varied across regions and between language groups and was subject to certain rules, and that their spiritual significance can be traced directly to epic creation stories. The implications of this paper are consistent with the earlier New South Wales and Victorian studies: regional variations exist in Queensland in relation to the (pre-colonial, colonial and post-colonial) historic relationship between Aboriginal communities and koalas and that close consultation with Aboriginal communities needs to be taken into consideration when planning conservation measures relating to koalas. [ABSTRACT FROM AUTHOR]

Denitrification transforms nitrogen applied as fertilizer and emits N2O, which is a potent greenhouse gas. Very little is known about the identities of abundant and active denitrifiers in agricultural soils. We coupled DNA stable-isotope probing (DNA-SIP) with flow-through reactors (FTRs) to detect active agricultural soil denitrifiers. The FTRs were incubated with nitrate and 13C6-glucose under anoxic conditions and sampled at multiple time points. Labelled DNA from active microorganisms was analyzed by 16S rRNA gene fingerprinting, amplicon and shotgun metagenomic sequencing. Taxonomic representation of heavy fractions was consistent across sites and time points, including Betaproteobacteria (71%; Janthinobacterium, Acidovorax, Azoarcus and Dechloromonas), Alphaproteobacteria (8%; Rhizobium), Gammaproteobacteria (4%; Pseudomonas) and Actinobacteria (4%; Streptomycetaceae). Most nitrite-reductase reads from heavy DNA annotated to the copper-containing form ( nirK). Assigned taxonomies of active denitrifiers based on reads matching the nirK gene were comparable to those obtained through nitric oxide ( norB) and RNA polymerase ( rpoB) annotations but not the nitrous oxide reductase gene ( nosZ). Analysis of recovered metagenomes from heavy DNA demonstrated extensive nirK sequence family diversity, including novel taxonomic groups that are not captured by existing primers. [ABSTRACT FROM AUTHOR]

Abstract: The study of ancient massive ground ice and sediment-rich ice bodies not only allows an understanding of the stability of permafrost, but also offers the possibility to understand the long-term preservation and viability of microbes within these ice bodies. Although microorganisms have been identified in ancient bodies of ground ice and permafrost, there still is a lack of convincing evidence that the microbes were metabolically active within the ice. In this study, we combine geomicrobiology methods with the measurements of occluded gasses in four ancient massive ground ice bodies to provide evidence of microbial respiration. In our samples, abundant cold-adapted heterotroph microorganisms were identified using culture-dependent and -independent methods. The occluded gas measurements, with low δ(O2/Ar) (less than −21.4%) and δ13CCO2 (as low as −25.2‰) values and high δ18OO2 (up to +16.3‰) values are suggestive of in situ consumption of O2 by heterotrophic psychrophilic bacteria living within the ice matrix. Overall, the multi-disciplinary approach provides a strong set of tools from which to infer metabolic activity within bodies of ground ice. The analysis of δ(O2/Ar), δ18OO2 and δ13CCO2 from occluded gasses in ice are strong isotope biosignatures that could allow detecting evidence of life on other planetary icy bodies such as Mars. [Copyright &y& Elsevier]

Abstract: Endostromatolites (cf. fissure calcretes), which possess microbial evidence for a biogenic origin, are also thought to preserve isotopic biosignatures. In this study, a multi-proxy approach combining (micro)morphological, geochemical and isotopic analyses of middle Holocene age endostromatolites within sub-horizontal fissures in dolomitic limestone outcrops in the Haughton impact crater region (Devon Island, NU) was used to determine their origin (abiotic versus biogenic) and to identify potential isotope biosignatures. The micro-morphologies of the endostromatolites revealed some structures typical of a physico-chemical origin, whereas the presence of rod-shape particles and filamentous structures was more reminiscent of biologically-induced forms. The endostromatolites have δ 13C and δ 18O compositions reaching maximum values of 7.2‰ and −11.2‰, respectively. Positive relations between the elemental (Mg, Sr) and isotopic (δ 18O and δ 13C) composition of the endostromatolites are indicative of an evaporative enrichment process of the meteoric water infiltrating the fissures prior to calcite precipitation. However, the positive δ 13CTOC–δ 13CCaCO3 relation in the endostromatolites is strongly indicative that they were microbially-mediated. In support of a microbial origin, mostly aerobic heterotrophic bacteria that have been linked to both carbonate dissolution and mineralization were observed in the microbial diversity of the endostromatolites. However, the results are inconclusive to attribute the formation of the endostromatolites solely to a biologically-induced mineralization, but instead, favor a more complex origin that involved abiotic (evaporation), and to some extent, biological processes prior to and during calcite precipitation. Considering that the endostromatolites result from microbially-influenced mineralization, the effects of physico-chemical processes on the geochemical and isotopic composition of the endostromatolites were much greater than the effect of the biological processes. Thus, it seems that preservation of isotopic biosignatures in secondary carbonate precipitates is dependent on the sequence of processes generating chemical and isotopic modifications of the solution prior to calcite precipitation, the mechanism and condition (equilibrium or kinetic) of formation and post-fossilization alteration processes. [Copyright &y& Elsevier]

Abstract: In this study, various approaches that can potentially distinguish between vapor- and liquid-derived ground ice in the martian regolith (petrography, geochemistry, stable O-H, CO2-O2-N2 mposition) are examined using terrestrial ground ice examples. Although the stable O-H Isotope composition ratios can distinguish between vapor- and liquid-derived terrestrial ground ice, there might be to much mixing between the various water reservoirs on Mars to effectively use it, and, like on Earth, petrographic and geochemical approaches need to be complemented with additional supporting evidences. Of the different approaches currently being employed to determine the origin of terrestrial massive ground ice and icy sediments, it is the concentration of CO2 and the O2/Ar, N2/Ar and N2/O2 ratios of air entrapped in the ice that has proven to be the less ambiguous and most discriminatory. This is because the molar ratios of atmospheric gases change during their dissolution in water due to differences in their relative solubilities, thus providing distinctive ratios for the dissolved gases. The gas composition of air entrapped in the ice not only distinguishes between vapor- and liquid-derived ground ice, but any deviation from the theoretical dissolved values can provide insights into potential physical and biological processes operating in the subsurface, a key component for astrobiology. [Copyright &y& Elsevier]

Abstract: A massive ground-ice body was found exposed in the headwall of a thaw flow developed within the Chapman Lake terminal moraine complex on the Blackstone Plateau (Ogilvie Mountains, central Yukon Territory), which is contemporaneous to the Reid glaciation. Based on visible cryostructures in the 4-m-high headwall, two units were identified: massive ground ice, overlain sharply by 2 m of icy diamicton. The nature and origin of the Chapman Lake massive ground ice was determined using cryostratigraphy, petrography, stable O–H isotopes and the molar concentration of occluded gases (CO2, O2, N2 and Ar) entrapped in the ice, a new technique in the field of periglacial geomorphology that allows to distinguish between glacial and non-glacial intrasedimental ice. Collectively, the results indicate that the Chapman Lake massive ground ice formed by firn densification with limited melting–refreezing and underwent deformation near its margin. Given that the massive ground-ice body consists of relict glacier ice, it suggests that permafrost persisted, at least locally, on plateau areas in the central Yukon Territory since the middle Pleistocene. In addition, the d value of Chapman Lake relict glacier ice suggests that the ice covering the area during the Reid glaciation originated from a local alpine glaciation in the Ogilvie Mountains. [Copyright &y& Elsevier]

Abstract: Acidic SO4–Ca–Fe waters are discharging from sandstone bedrock overlying pyrite-rich shales along the Dempster Highway near Eagle Plains, northern Yukon Territory. Although evidence of acid drainage was present prior to the construction of the Dempster Highway in the 1970''s, the removal of surficial sediments during its construction amplified the release of acidity by allowing the active layer to penetrate into the freshly exposed pyrite-rich shale. Acid drainage originating from the excavated area has a pH value averaging 3.1±0.3 and over 5 g/L of dissolved solids (SO4 2− =3915 mg/L, Fetotal =459 mg/L, Ca2+ =418 mg/L and Altotal =83.6 mg/L) whereas the unaffected drainage has a pH greater than 4.4 and total dissolved solids in the 100 to 200 mg/L range. Geochemical modeling of the surface waters and active layer pore water using PHREEQC hydrogeochemical computer code predicted saturation in Fe-hydroxide and Fe-sulfate minerals, which is confirmed by the observation of abundant ferrihydrite precipitates along the acidified stream. The solute concentrations of the acidified stream and active layer soluble ions versus SO4 plot on very similar slopes, suggesting a recycling of solutes. It is suggested that the effect of seasonal freeze-thaw of the active layer plays an important role in sustaining acidity in the stream. Freeze-back of the acid waters in the active layer produces both Fe-sulfate minerals and residual sulfuric acid. During the thaw season, this acidity is released, thus enhancing further dissolution of alumino-silicate minerals. The release of these contaminants, including acidity, not only causes a perturbation of the water quality, but also has a negative impact on the sensitive Arctic ecosystem, by disturbing the local permafrost conditions. [Copyright &y& Elsevier]

This study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in Akshayuk Pass, southern Cumberland Peninsula (Baffin Island), a region underlain by granitic and gneissic rocks of the Precambrian Canadian Shield. Strontium isotope ratios (87Sr/86Sr) indicate that the major source of calcium is derived from the local dissolution of fracture-filling calcite and a minor source is derived from silicate weathering. The calcite crusts have δ13C values between 1.6‰and 12.0‰and δ18O values in the –13.0‰and –7.9‰range. These values are highly enriched over the predicted isotopic values based on the δ13CDIC and δ18O of the local water and temperature at which calcite precipitation occurred. The isotopic enrichments are attributed to a combination of both equilibrium and kinetic evaporation and were verified experimentally. The series of evaporative experiments indicate that kinetic evaporation produces a far-from-equilibrium isotope effect on both the δ13C and δ18O composition of the precipitating calcite (13CKIE CaCO3–CO2 between 20.2‰and 40.5‰VPDB; 18OKIE averaging 34.9% ± 3.7% VSMOW). Based on these results, the formation of the calcite crusts is ascribed to the evaporation of stagnating ephemeral lakes and streams following the retreat of valley glaciers. Given the >1500 m difference in heights between the highland and the valley, the katabatic winds originating from the Penny Ice Cap can act as a catalyst to increase the rate of evaporation. In addition, radiocarbon dating of ten of these crusts yielded Holocene ages (7640 cal (calibrated) BP to modern). These results suggest that the maximum expansion of Holocene valley glacier in Akshayuk Pass, previously thought to have occurred during the Little Ice Age, is probably much older. [ABSTRACT FROM AUTHOR]

Moonmilk, which is often seen coating walls in temperate caves, is a porous secondary calcite deposit composed of an aggregate of microcrystalline calcite and water. This study, based on moonmilk deposits found in Caverne de l'Ours, Ottawa Valley region, proposes a model for its formation based on the calcite and water isotope chemistry and evaluates its use as a climatic proxy. In Caverne de l'Ours, non-calcitic mineral inclusions protrude from the bedrock (Grenville marble) into the moonmilk, while others are entirely enclosed within the moonmilk. This observation suggests a mechanism of bedrock dissolution and reprecipitation for the formation of moonmilk, which is controlled by the changing seasonal climate in the cave. The δ18O of the moonmilk interstial water indicates that the condensation of water vapour occurs mostly in winter and spring. The condensation of water vapour on the surface of the walls allows for the dissolution of the Grenville marble and releases ions necessary for the precipitation of moonmilk. The δ18O and δ13C of calcite and δ18O of the moonmilk interstitial water indicate that precipitation of moonmilk occurs during summer and fall. During these seasons, the relative humidity in the cave decreases resulting in moonmilk growth through the slow evaporation of calcite-saturated water. A comparison of the δ18O record of moonmilk from caves in Gaspésie (Canada) and from Aven d'Orgnac (France) shows that this material retains temperature information valuable for paleoclimatic reconstructions. [ABSTRACT FROM AUTHOR]

Rat paravalbumin (PV) and oncomodulin (OM) display considerable sequence similarity and structural similarity, but differ in the and selectivity of metal binding to their CD site a Ca2+/Mg2+-mixed site in PV and a Ca2+-specific site in OM. In an attempt to identify the structural basis for these differnces mutations were introduced in the previously generated [W102]PV mutant contain a unique trytophan as a conformational-sensitive probe inside the hydrophobic core. In the present report. We sustituted selected amino acid residues in the CD site of PV by those present at identical positions in OM, One mutant protein, named [F66, W102]PV, has one new substitution in which isoleucine at position 66 was exchanged by phenylalamine. The second mutant protein, [146, 150, L58, F66, W102] PV, has four new substitutions, namely V46→I, L50→I,I58→L and I66→F, Tryptophan fluorescence and difference spectrophotometry indicated that the mutation do not alter significance the hydrophobic core. Both mutant proteins display two-binding sites of identical affinities with intinsic affinity constant Kca2+ of 2.9&times107 M-1 for [F66, W102 ]PV and 1.7× M-1 for [146, 150, L58, F66, W102] PV and KMg2+ of 3.1×104 M-1 for [F66, W102]PV and 1.9×104 M-3for [146,150,L58, F66, W102]PV. Thus the five-residue substitution, but not the two-residues one, leads to a small decrease of affinity compared to [W102]PV (Kca2+=2.7× 107 M-1, KMg2+=4.4 × 104 M-1). [ABSTRACT FROM AUTHOR]

Perennially ice-covered lakes that host benthic microbial ecosystems are present in many regions of Antarctica. Lake Untersee is an ultra-oligotrophic lake that is substantially different from any other lakes on the continent as it does not develop a seasonal moat and therefore shares similarities to sub-glacial lakes where they are sealed to the atmosphere. Here, we determine the source of major solutes and carbon to Lake Untersee, evaluate the carbon cycling and assess the metabolic functioning of microbial mats using an isotope geochemistry approach. The findings suggest that the glacial meltwater recharging the closed-basin and well-sealed Lake Untersee largely determines the major solute chemistry of the oxic water column with plagioclase and alumino-silicate weathering contributing < 5% of the Ca2+–Na+ solutes to the lake. The TIC concentration in the lake is very low and is sourced from melting of glacial ice and direct release of occluded CO2 gases into the water column. The comparison of δ13CTIC of the oxic lake waters with the δ13C in the top microbial mat layer show no fractionation due to non-discriminating photosynthetic fixation of HCO3– in the high pH and carbon-starved water. The 14C results indicate that phototrophs are also fixing respired CO2 from heterotrophic metabolism of the underlying microbial mats layers. The findings provide insights into the development of collaboration in carbon partitioning within the microbial mats to support their growth in a carbon-starved ecosystem. [ABSTRACT FROM AUTHOR]

This article collects and presents nineteenth-century ethnographic evidence from the Newer Volcanics Province of Australia and explores how volcanism was recorded and understood in Aboriginal oral traditions. It investigates whether Aboriginal Australian oral traditions can be understood as persistent eyewitness accounts of volcanic eruptions in the Newer Volcanics Province, how and what kind of geological and volcanological knowledge was embedded within Aboriginal Australian oral traditions, and considers what value the ethnographic evidence has for understanding both the socio-cultural and geological histories of the Newer Volcanics Province. • Europeans collected ethnographic evidence of Aboriginal Australian oral traditions. • Oral traditions include creation myths and placenames from the Newer Volcanics Province. • Oral traditions demonstrate extensive Aboriginal Australian volcanological knowledge. • History enriches the cultural and geological heritage of the Newer Volcanics Province. [ABSTRACT FROM AUTHOR]

The study presents a detailed investigation of S-isotope systematics of pyrite from Cambrian-Ordovician sedimentary rocks along the eastern flank of the Michigan Basin, Ontario, Canada. Whole-rock and secondary-ion mass spectrometry (SIMS) pyrite analyses of 34S/32S were undertaken in association with a detailed petrographic investigation of the different crystal morphologies to better constrain the diagenetic history of the sedimentary rocks by informing about the processes of pyrite formation. The broad range of SIMS isotopic data (i.e., −37.1‰ < δ34S < +80.3‰) reveals that three different stratigraphic units experienced different diagenetic pathways of pyrite formation: (1) the Ordovician shales containing primarily biogenic framboidal pyrite formed during two different crystal growth phases (i.e., early diagenesis with δ34S from ~−20 to +5.0‰ and late diagenesis with δ34S from ~+20.0 to +80‰); (2) the Cobourg formation containing relatively 34S-depleted tabular pyrite (i.e., δ34S ~ −25‰) which likely reflects a late replacement phase after sulphate mineral dissolution; and (3) the Cambrian and the Ordovician Black River Group carbonates that share a genetic link in pyrite formation and a complex history of hydrothermal fluid movement. In general, the pyrite in the studied stratigraphic sequence seems to have retained S-isotope signatures indicative of a closed system at the scale of pyrite formation. This study demonstrates the importance of investigating the isotopic systematics of S-species at the microscale level to help understand the evolution of sedimentary basins over geological time scales. • Reconstruction of the diagenetic history of the Michigan Basin • Evidence for closed system pyrite formation • Sedimentary pyrite is heterogeneous in morphology and isotopic composition • Formation of "superheavy" pyrite formation unrelated to anaerobic methane oxidation [ABSTRACT FROM AUTHOR]

Porewater extractions and acid leachates of rock core from a 250 m thick sequence of low-permeability Ordovician-age shales and limestones, on the eastern flank of the Michigan Basin, were analysed for strontium isotope ratios in an attempt to infer porewater ages from observed 87Sr/86Sr enrichments. The porewaters originated as Ordovician seawater, which subsequently mixed with evaporated Silurian seawater infiltrating from above, and, to some extent, with a deep brine—with an enriched 87Sr/86Sr signature—from the underlying crystalline shield or deep basin. The porewater 87Sr/86Sr ratios are more radiogenic than contemporaneous seawater but show no obvious correlation to those leached from the solid rock phases. Accepting that the initial 87Sr/86Sr signatures in porewaters were dominated by Late Silurian brine, potentially with an additional deep brine component, the excess of radiogenic 87Sr appears to represent ingrowth from 87Rb decay over a time span of some 420 million years, approaching the depositional age of the rocks. Similarly, Rb/Sr errochron ages of acid leachates of solid phases, and the calculated initial 87Sr/86Sr isotopic ratios, are consistent with a proposition that the calcites inherited their Sr from Ordovician seawater and were dolomitized shortly afterwards by infiltrating Mg-enriched evaporative brine, indicating long-term conservative behaviour for the enclosing carbonate rocks. The errochron for leachates from (alumino)silicates yields a high initial 87Sr/86Sr, but with an errochron age of about 340 ± 48 Ma, likely owing to variable admixtures of diagenetic illite in the shales. Overall, the data provide evidence for a stable hydrologic regime since Paleozoic time. [ABSTRACT FROM AUTHOR]

Ice-wedge activity can be used to reconstruct past environmental conditions. We investigated the moisture source and timing of ice-wedge formation on the Blackstone Plateau. A section of permafrost exposed ice wedges that developed at two distinct depths: the first set formed syngenetically and penetrated alluvial silts from the top of permafrost; the second set, truncated by an erosional or thaw contact, was found solely in icy muddy gravels (>3.1 m depth). The δ18O and D-excess records of the ice wedges suggest that they formed from freezing of snow meltwater whose isotopic composition evolved during meltout. The 14CDOC results suggest that climate was favorable to ice-wedge growth between 32,000–30,000 and 14,000–12,500 cal yr BP, but there was likely a hiatus during the last glacial maximum due to climate being too dry. During the early to mid-Holocene, ice wedges were inactive as a result of warmer and wetter climate. Ice wedge re-initiated around 6360 cal yr BP, with a peak in activity between 3980 and 920 cal yr BP, a period characterized by cool and moist climate. Overall, timing of ice-wedge activity was broadly consistent with the climate and vegetation evolution in the western Arctic. [ABSTRACT FROM AUTHOR]

Abstract This paper describes a technique of making carbonate by rapid CO 2 capture from groundwater for direct measurement of the 14C content by accelerator mass spectrometry (AMS). The DIC in groundwater was extracted from acidified water in the form of carbon dioxide (CO 2), and transferred into saturated barium hydroxide solution to form barium carbonate (BaCO 3). After the BaCO 3 precipitate was freeze-dried, it was mixed with a metal powder and pressed into an AMS target for measurement. The behaviors of Si, Al, Fe and Ta powder as the binder with carbonate were evaluated. The C3+ currents from carbonate targets mixed with Fe or Ta were found generally larger than those with Si or Al by a factor of two. The baked Ta was shown to produce fewer contaminating 14C counts than all the others, with or without baking. The CaCO 3 /Ta and BaCO 3 /Ta mass mixing ratios in the range from 1:2 to 1:4 and in 1:1.5, respectively, produced optimized currents. The precision and accuracy of the measurement by direct CaCO 3 or BaCO 3 sputtering using Ta as the binder, were evaluated in comparison to a selected reference material. The agreement was reasonably good between the direct carbonate measurement and the high precision measurement through combustion and graphitization. These findings support the further development of a rapid assessment method directly from field work to measurement. [ABSTRACT FROM AUTHOR]

Highlights • A reconstruction of the Paleozoic maturation history of OM. • Evidence for biodegradation of n -alkanes associated with microbial CH 4. • Timing of OM biodegradation constrained as a late diagenetic event. Abstract Previous characterization of a low permeability (10−16 ≤ K h ≤ 10−12 m s−1) and high salinity (> 5 M of Cl−, > 10× seawater salinity) aquiclude, in Upper Ordovician-aged sediments situated on the eastern flank of the Michigan Basin, where a deep geological repository for low and intermediate level nuclear waste is proposed, suggested a microbial origin for CH 4 and CO 2 based on their stable isotope values. CH 4 is believed to have been produced and trapped during the Paleozoic in a relatively discrete and high organic matter (OM) horizon at the shale/carbonate transition. To further investigate the efficiency of confinement of this aquiclude, here we present detailed isotopic and geochemical stratigraphic profiles of OM and biomarkers, with the objective of understanding the origin of CH 4 and its relative timing of confinement. Classical diagnostic ratios of polycyclic aromatic hydrocarbons, relative abundances of hopanes and degraded hopanes coupled to dual compound-specific isotopic analysis of n- alkanes, as well as δ13C analysis on different fractions of OM were measured. A partitioning of the Ordovician sedimentary succession into two systems is observed with an upper system that is self-sourced and confined, hosting the microbially derived CH 4 with evidence of late diagenetic OM biodegradation and a lower system that reveals later secondary oil migration which has overprinted the organic geochemical record. We propose a conceptual model that would explain the generation and preservation of this paleo-bioreactor over time using the maturation history reconstruction derived from this dataset. This work not only provides essential field empirical evidence of a relationship between methanogenesis and late diagenetic biodegradation, but also shows the power of dual-compound-specific isotope analyses in deciphering between different maturation processes affecting OM in natural subsurface settings. [ABSTRACT FROM AUTHOR]

The long lived radioisotope 129 I is a uranium fission product, and an environmental contaminant of the nuclear age. Consequently, it can trace anthropogenic releases of 129 I in watersheds, and has been identified as a potential means to distinguish water sources in discharge (Nimz, 1998). The purpose of this work was to identify the sources and mass input of 129 I and trace the transport, partitioning and mass balance of 129 I over time in a remote watershed. We monitored 129 I and other geochemical and isotope tracers (e.g. δ 14 C DIC , δ 13 C DIC , δ 2 H, δ 18 O, etc.) in precipitation and discharge from the Wolf Creek Research Basin (WCRB), a discontinuous permafrost watershed in the Yukon Territory, Canada, and evaluated the use of 129 I as a water end-member tracer. Radiocarbon and geochemical tracers of weathering show that discharge is comprised of (i) groundwater baseflow that has recharged under open system conditions, (ii) spring freshet meltwater that has derived solutes through closed-system interaction with saturated soils, and (iii) active layer drainage. The abundance of 129 I and the 129 I/ 127 I ratio correlated with geochemical tracers suggests varying contributions of these three water end-members to discharge. The 129 I concentration was highest at the onset of freshet, reaching 17.4 × 10 6 atoms/L, and likely reflects the lack of interaction between meltwater and organic matter at that time. This peak in 129 I was followed by a decline over the summer to its lowest value. Mass balance calculations of the 129 I budget show that the input to the watershed via precipitation is nearly one order of magnitude higher than the output suggesting that such arctic watersheds accumulate nearly 90% of the annual input, primarily in soil organic matter. Temporal variations in discharge 129 I concentrations correlated with changes in discharge water sources suggesting that 129 I is a promising hydrologic tracer, particularly when used in concert with other stable and radioisotopes. [ABSTRACT FROM AUTHOR]

Holocene climate change resulted in major vegetation reorganization in sub-arctic Canada near modern treeline. However, little is known of the effects of long-term climate change on boreal forest composition and fire regimes below treeline in this region. We present a high-resolution vegetation and fire history from two sites within the modern boreal forest in the central Northwest Territories, Canada, to provide new insight on sub-arctic vegetation response to Holocene climate dynamics and the role of fire in boreal ecosystems. Palynological analysis of sediments retrieved from Waite and Danny's lakes (informal) is used to reconstruct regional vegetation dynamics and boreal fire regimes. The longer Danny's Lake record documents treeline expansion beginning at ca. 7430–7220 cal yr BP. Integration of our new data with previous work shows that treeline expanded between ca. 4050 cal. yr BP and ca. 3840 cal yr BP at a rate of ca. 50 m/yr in response to the 1–2 °C increase in temperature estimated for the Holocene Thermal Maximum. Forest fires were relatively frequent during the early Holocene, before declining in frequency in response to development of cooler and wetter climate conditions associated with the Neoglacial (beginning after ca. 2200–2320 cal yr BP). We document a trend of increasing fire frequency in the 20th century that is correlated with warming at this time. These dynamics south of modern treeline provide insight into factors creating heterogeneity in plant community responses to large-scale climate events in high northern latitudes and suggest that large scale reorganization of boreal vegetation and fire regimes can be expected over the coming decades. [ABSTRACT FROM AUTHOR]