RATIONALE:The stable carbon (δ13C) and nitrogen (δ15N) isotope composition of human bone and tissues encodes dietary information that in some circumstances can be attributed to geographical location. While there is a global dataset amounting to > 4000 samples, limited data are available for the Australasian region. METHODS:One hundred and seven nail/hair samples were detergent and solvent pretreated and analysed for δ13C and δ15N composition, sourced from individuals normally residing in southern Australia (temperate), northern Australia (seasonal tropical) and urban Papua New Guinea (tropical). Isotope values for nails were converted to hair keratin equivalent values using accepted fractionation factors. The results were compared with each other, and with the global datasets available from Europe, Asia, Africa and the Americas. RESULTS:The southern Australian and Papua New Guinean data exhibit a similar mean and range to each other for both δ13C and δ15N values, comparable to results for some regions of Europe and Asia. The northern Australian data extends to higher δ13C values than the other groups due to a greater component of carbon in the diet ultimately from a C4 source. Vegetarians exhibit a similar range to the omnivores in δ13C but tend to lower δ15N values. CONCLUSIONS:Global supply chains and industrial fertilizer use have reduced the range δ13C and nitrogen δ15N values in the samples in this study, as has been the case globally. The range of values observed reflects the ability of consumers to access local produce from supermarkets or local markets. The Australasian data tend to lower δ13C values than the global average, indicating a dominance of carbon assimilated by C3 photosynthesis in the diet. While similar to some European and Asian populations, δ13C values are lower than from regions with a high reliance on carbon assimilated by C4 photosynthesis, including the Americas and parts of Africa.

Nearly two thirds of the world's population depend on monsoon rainfall, with monsoon failure and extreme precipitation affecting societies for millennia. Monsoon hydroclimate is predicted to change as the climate warms, albeit with uncertain regional trajectories. Multiple glacial-interglacial terrestrial records of east Asian monsoon variability exist, but there are no terrestrial records of equivalent length from the coupled Indo-Australian monsoon at its southern limit - Australia. We present a continuous 150,000-year lacustrine record of monsoon dynamics from the core monsoon region of northern Australia based on the proportion of dryland tree pollen in the total dryland pollen spectra and the hydrogen isotope composition of long chain n-alkanes. We show that rainfall at the site depends strongly on sea level, which changes proximity of the coast to the site by 320 km over the last glacial-interglacial cycle. Long-term trends in rainfall are broadly anti-phased with the east Asian monsoon modulated by coastal proximity. The record also contains multiple, short intervals (similar to 2 to < 10,000 years) of large changes in tree cover (from 5 to 95 % tree pollen over 3000 years in one instance). Changes in tree cover are frequently but not always, accompanied by synchronous large changes in the other hydroclimate proxies. While these wetter periods cannot be easily ascribed to orbitally induced changes in insolation or coastal proximity, they are correlated with most Heinrich events. This relationship implies that strong asymmetry in inter-hemispheric monsoon rainfall might be one outcome of the current weakening in the strength of the Atlantic meridional overturning circulation, through a reduction in oceanic heat transfer from the Southern to the Northern Hemisphere.

Both pollen and the carbon isotope (delta C-1(3)) compositions of long chain n-alkanes (n-C29-31) are widely used to reconstruct changes in past vegetation in the tropics. Both approaches are able to infer the proportions of tree/shrub (C-3) and grass (C-4) biomass, with changes in these proportions generally interpreted to be driven by changes in hydroclimate. Both pollen and n-alkane delta C-1(3) records are subject to biases in production and transport to a site of deposition that may influence the interpretation of the record. Here we compare detailed 150,000-year pollen and n-alkane carbon isotope (delta C-1(3)) records from a lake in monsoonal northern Australia. There is a broad agreement between the two records at some times, with both identifying major wet periods of high tree/shrub C-3 terrestrial biomass during marine isotope stages 5 and 1. There are significant differences between the two records at other times. At times during glacial marine isotope stages 2 and 6, C-4 grass pollen comprised >80% of terrestrial pollen, whereas the n-C29-31 delta C-1(3) values indicate dominantly C-3 terrestrial biomass. These differences are the result of changes in the relative abundance and delta C-1(3) values of alkane inputs from within the lagoon itself that impact the delta C-1(3) value of the n-C29-31 'terrestrial' alkanes. The drivers of these changes include (i) changes in the biomass and delta C-1(3) value of aquatic vegetation (floating and submerged) that result from dramatic changes in lake level (ii) the changing importance of groundwater-derived dissolved inorganic carbon as a substrate for photosynthesis in the lake, (iii) changes in the proportion of sedge biomass in and around the lake that also accompany changes in lake level, and (iv) changes in the mix of C-3 and C-4 species comprising the sedge biomass in and around the lake. The significance of contributions of n-alkanes from aquatic and sedge sources to chain lengths usually considered to derive from terrestrial plants, may be underestimated in small, high productivity lacustrine environments, particularly in carbonate terranes.

Terrestrial proxy records of environmental change from the southern end of the coupled East Asian-IndoAustralian monsoon domain remain limited in number. Here we present multi-proxy Holocene n-alkane hydrogen isotope and pollen records from Girraween Lagoon, located in monsoonal northern Australia. We compare the Girraween record with two published speleothem isotope records available to the north and south of the lagoon, all within the region where rainfall is dominantly associated with the southward movement of the Intertropical Convergence Zone (ITCZ) in the Austral summer. All three sites record an initial period of general monsoon intensification between similar to 7.5 and 9 ka, but after this time the responses of the three records diverge. The records from the northern and southern sites reflect changes in the mean position of the ITCZ at its periphery that did not impact the Girraween site. The Girraween record clearly demonstrates a period of particularly enhanced monsoon rainfall between 3 and 5 ka. This period, when rainfall was dominated by deep convection was initiated by a sustained southerly shift in mean ITCZ position, which also resulted in a reduction in rainfall in southern Indonesia. Weakening of the monsoon at the Girraween site was initiated by strengthened ENSO teleconnections at 2.5-3 ka and was accompanied movement of the ITCZ to a more northerly position resulting in enhanced rainfall in southern Indonesia. The monsoon regime that was fully established by similar to 2 ka at Girraween Lagoon, has broadly been in place since that time.

At the time of European arrival on the Australian continent, sophisticated Indigenous societies practiced land management across Australia’s extensive tropical savannahs. Fire was one of the main tools people used to manipulate fuel loads and connectivity to reduce uncontrolled wildfire, maintain vegetation structure and enhance biodiversity. When this alteration of a ‘natural’ fire regime to a human-dominated fire regime occurred is not known. Here we assessed fire incidence and intensity over the past 150,000 years through a continuous lacustrine record by comparing the accumulation rates of micro-charcoal and stable polycyclic aromatic hydrocarbon that form during the combustion of vegetation. We also compared grass (mainly C 4 ) pollen as a percentage of total dryland pollen with the carbon isotope composition of the stable polycyclic aromatic hydrocarbon. We established with high statistical certainty that a change in fire regime occurred at least 11,000 years ago from less-frequent, more-intense fires to more-frequent, less-intense fires. This change marked the overprinting of a largely natural fire regime by one at least modulated by Indigenous management. Our findings demonstrate that human fire use has modified fire regimes throughout the Holocene and also show how people have managed the potential for the type of high-intensity fires that are likely to increase in the future.

The carbon and hydrogen isotope compositions (δ13C and δ2H) of sedimentary n-alkanes are excellent recorders of past vegetation and precipitation change. Yet, few studies have combined and compared n-alkanes in modern plants and paleoenvironmental records. Here we analyzed the δ13C and δ2H values of n-alkanes (δ13Calk and δ2Halk, respectively) from a 7-m-long sediment sequence in Lake Barrine, modern catchment soils, fallen leaf mixtures, rainforest tree leaves and grasses from tropical northeastern Australia. We exploited the correlation between the relative abundances, δ13C, and δ2H values of n-alkanes from fresh modern rainforest leaves, grasses, fallen leaves, soils and surface sediments. Based on this, we developed two binary mixing models to determine C3 plant abundances and the δ2H values of precipitation (δ2HP-R) to study rainfall and vegetation in the Lake Barrine catchment since 18.3 cal ka BP. Combining the results of this study with mean annual air temperature, pollen, and clastic influx, we reconstructed a robust climatic and environmental record for this site and compared it with other regional paleoenvironmental records. The modern samples indicate slight 13C enrichment and obvious 2H depletion in the n-alkanes from fresh rainforest leaves, fallen leaves, soils, and surface sediments, which is possibly due to microbial build-up of n-alkanes during decomposition. A broad consistency in regional paleoclimate trends was identified, including a cool, dry Last Glacial Maximum (23–17.0 cal ka BP), warmer, wetter last deglacial (17.0–14.9 cal ka BP), wetter with stable temperature Antarctic cold reversal (14.9–12.8 cal ka BP), (possibly) cooler, drier Younger Dryas (12.8–11.6 cal ka BP), warmer, wetter early-to-middle Holocene (11.6–5 cal ka BP) and cooler, slightly drier and more variable late Holocene (5 cal ka BP to the present).

A palynological record from Girraween Lagoon sediments (Darwin region of the Northern Territory, Australia) provides detailed long-term insight into tropical savanna vegetation community patterns, climatic and fire relationships, through Marine Isotope Stage 4 (MIS 4: 71-57 thousand years ago, ka) and Marine Isotope Stage 3 (MIS 3: 57-29 ka). Owing to a lack of data in reconstructing northern Australian environments, this paper looks to define and describe to a greater degree the nature and scope of these stadial and interstadial stages for the region. Girraween Lagoon simultaneously provides proximal palaeoecological data for the time and region of Aboriginal people's first arrival into Australia, also encompassing the late Pleistocene continental decline of megafauna. This study provides a dataset enabling full exploration of long-term people-landscape and faunalfloral interactions. Sea levels and associated variations imposed on the transportation of moisture and heat, held implications for MIS 4 and MIS 3 monsoon strength, which was particularly consequential for Girraween regional ecology. Results reveal a prolonged transition from wooded- to grassy-savanna, into a cool drier semiarid savanna. Increasingly episodic delivery of moisture influenced the permanency of freshwater in the landscape.

The carbon and hydrogen isotope compositions (8 13 C and 8 2 H) of sedimentary n-alkanes are excellent recorders of past vegetation and precipitation change. Yet, few studies have combined and compared n-alkanes in modern plants and paleoenvironmental records. Here we analyzed the 8 13 C and 8 2 H values of n-alkanes (8 13 C alk and 8 2 H alk , respectively) from a 7-m-long sediment sequence in Lake Barrine, modern catchment soils, fallen leaf mixtures, rainforest tree leaves and grasses from tropical northeastern Australia. We exploited the correlation between the relative abundances, 8 13 C, and 8 2 H values of n-alkanes from fresh modern rainforest leaves, grasses, fallen leaves, soils and surface sediments. Based on this, we developed two binary mixing models to determine C 3 plant abundances and the 8 2 H values of precipitation (8 2 H P-R ) to study rainfall and vegetation in the Lake Barrine catchment since 18.3 cal ka BP. Combining the results of this study with mean annual air temperature, pollen, and clastic influx, we reconstructed a robust climatic and environmental record for this site and compared it with other regional paleoenvironmental records. The modern samples indicate slight 13 C enrichment and obvious 2 H depletion in the n-alkanes from fresh rainforest leaves, fallen leaves, soils, and surface sediments, which is possibly due to microbial build-up of n-alkanes during decomposition. A broad consistency in regional paleoclimate trends was identified, including a cool, dry Last Glacial Maximum (23-17.0 cal ka BP), warmer, wetter last deglacial (17.0-14.9 cal ka BP), wetter with stable temperature Antarctic cold reversal (14.9-12.8 cal ka BP), (possibly) cooler, drier Younger Dryas (12.8-11.6 cal ka BP), warmer, wetter early-to-middle Holocene (11.6-5 cal ka BP) and cooler, slightly drier and more variable late Holocene (5 cal ka BP to the present).

Abstract Nearly two thirds of the world’s population depend on monsoon rainfall. Monsoon failure and extreme precipitation have affected societies for millennia. The distribution and amount of monsoon precipitation is predicted to change as the climate warms, albeit with uncertain regional trajectories. Multiple glacial-interglacial terrestrial records of east Asian monsoon variability have been developed, but there are no terrestrial records of equivalent length of the coupled Indo-Australian monsoon at the southern monsoon limit — Australia. Here we present a continuous, absolute-dated, 150,000-year record of monsoon dynamics from a permanent lagoon in the core monsoon region of northern Australia. We show that Australian rainfall is broadly anti-phased with the East Asian monsoon. We identify periods of intense monsoon activity associated with high local insolation in Marine Isotope Stage 5 during ‘megalake’ phases in Australia’s arid interior. We also identify periods of monsoon intensification that are associated with Heinrich events and coincide with weak monsoon events in East Asia. The results suggest that strong asymmetry in inter-hemispheric monsoon rainfall might accompany the current weakening in the strength of the Atlantic meridional overturning circulation. This asymmetry will involve drying in the heavily populated regions north of the equator, and intensification of rainfall in northern Australia.

In this study we assessed the effects of an experimental drought on the reproductive phenology and ecophysiology of a rainforest tree community in the Wet Tropics of Queensland. We found that, although the drought increased fruiting activity in the community relative to the reference plot, species-level response was varied in both phenology and physiology.

We present a record of hydroclimatic change over the Holocene from Kinrara Lake, in a seasonally dry savanna location in north-eastern Australia. The record is derived from the oxygen (818O) and carbon stable isotope (813C) composition of endogenic and biogenic (gastropod) carbonate. The stable isotope proxy records are complemented by elemental geochemical (Itrax) and sedimentological proxy data providing a record of hydrologic and climate change, spanning 10.5 ka to the present day. Two main forms of endogenic carbonate occur in the lake sediments; (i) carbonate associated with biofilms during the early-Holocene, under drier-than-modern conditions, (ii) photosynthetic and evaporatively-enriched precipitates in the late-Holocene, associated with enhanced climate variability inducing drought periods. Strong relationships between negative 818O values and increased Ti, Rb, Fe/Mn, inc/coh, are linked with strengthened monsoon conditions, while enhanced periods of dryness are inferred from more positive 818O values, increased Ca/ n-ary sumation Fe, Ti, Al, and subsequent intensifications in lake productivity (higher Si/Ti, S/Ti, Mn/Ti). Three distinct phases can be identified in palaeohydrological history of the lake; (i) a relatively stable drier-than-modern phase during the early-Holocene (10.5 to 8.2 ka), (2) a significantly wetter-than-modern, monsoon-dominated phase through the mid-Holocene into the late-Holocene (8.2-2.8 cal yr BP), and (3) after 2.8 ka, increased intensity of ENSO-related rainfall variability during the late Holocene, continuing into the present.

River sharks (Glyphis spp.) and some sawfishes (Pristidae) inhabit riverine environments, although their long-term habitat use patterns are poorly known. We investigated the diadromous movements of the northern river shark (Glyphis garricki), speartooth shark (Glyphis glyphis), narrow sawfish (Anoxypristis cuspidata), and largetooth sawfish (Pristis pristis) using in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on vertebrae to recover elemental ratios over each individual's lifetime. We also measured elemental ratios for the bull shark (Carcharhinus leucas) and a range of inshore and offshore stenohaline marine species to assist in interpretation of results. Barium (Ba) was found to be an effective indicator of freshwater use, whereas lithium (Li) and strontium (Sr) were effective indicators of marine water use. The relationships between Ba and Li and Ba and Sr were negatively correlated, whereas the relationship between Li and Sr was positively correlated. Both river shark species had elemental signatures indicative of prolonged use of upper-estuarine environments, whereas adults appear to mainly use lower-estuarine environments rather than marine environments. Decreases in Li:Ba and Sr:Ba at the end of the prenatal growth zone of P. pristis samples indicated that parturition likely occurs in fresh water. There was limited evidence of prolonged riverine habitat use for A. cuspidata. The results of this study support elemental-environment relationships observed in teleost otoliths and indicate that in situ LA-ICP-MS elemental characterization is applicable to a wide range of elasmobranch species as a discriminator for use and movement across salinity gradients. A greater understanding of processes that lead to element incorporation in vertebrae, and relative concentrations in vertebrae with respect to the ambient environment, will improve the applicability of elemental analysis to understand movements across the life history of elasmobranchs into the future.

AimsInformed management of savanna systems depends on understanding determinates of composition, structure and function, particularly in relation to woody-plant components. This understanding needs to be regionally based, both past and present. In this study, Holocene plant patterns are explored at a site within the eucalypt savannas of northern Australia. Australian savannas are the least developed globally and uniquely placed to track ecological change. LocationNorthern Territory, Australia. MethodsPalynological analyses were undertaken on a 5-m sediment core, spanning the last 10,700 calendar years. Pollen was categorised to capture vegetation type, classified further according to plant function and/or environmental response. Detrended Correspondence Analysis was used to quantify ecological dissimilarities through time. ResultsAt the Pleistocene transition, grasses were abundant then declined and remained low relative to increased woody cover from the mid-late Holocene. Savanna composition gradually transitioned from Corymbia to Eucalyptus dominance until significantly disturbed by a phase of repeated, extreme climate events. Highest non-savanna variability in terrestrial and wetland plant types formed mixed vegetation communities through the mid-Holocene. ConclusionsSavannas are not homogeneous but the product of plant changes in multiple dimensions. In the Northern Territory, dynamic though restricted non-eucalypt shifts are embedded within larger, slower eucalypt change processes. Primary climate-vegetation relationships determine the long-term fire regime. The role of large but infrequent disturbance events in maintaining savanna diversity are significant, in degrees of impact on tree-grass turnover, its form and the extent of vegetation recovery. People's landscape interactions were found to be interwoven within this feedback hierarchy.

The stable carbon (δ13C) and nitrogen (δ15N) isotope composition of human bone collagen is increasingly used to investigate past mobility and subsistence strategies. This study presents a compilation of 1298 carbon and nitrogen isotope analyses of archaeological human bone collagen from the British Isles spanning much of the Holocene, along with a compilation of 4148 analyses of modern and ancient isotope analyses from the major marine and terrestrial dietary resources from the same region. We convert ancient human stable isotope data to modern diet equivalent (MDE) values for humans, and convert the isotope composition of ancient dietary items to modern tissue equivalent (MTE) isotope values. These conversions enable a direct comparison of ancient and modern datasets. Results for food groups (plants, grain, herbivores, omnivores, shellfish, freshwater fish and marine fish) show a remarkably broad range of δ13CMTE values from ∼-36 to −7‰ and δ15NMTE values from ∼-2 to +21‰ and we provide estimates for each food type that can be used in dietary reconstruction in the absence of site-specific data. We further show that there is no significant change in terrestrial stable isotope baseline values over the Holocene, with observed variability in baseline values due to local eco-physiological, edaphic and microclimatic factors. The range of values expressed in the human sample set from the beginning of the Iron Age is relatively tightly clustered with 50% of all human modern diet equivalent results falling within a ∼2‰ range in δ13CMDE values (−25.5 to −27.5‰) and a ∼3.5‰ range in δ15NMDE values from (+4‰ to +8‰). From the Iron Age to post-medieval times there is a consistent progressive shift to higher δ13CMDE and δ15NMDE values at the population level. This shift likely reflects a combination of successive innovations associated with food production, preservation and transport that enabled a broader cross-section of the population of the British Isles to incorporate a higher proportion of animal, and particularly marine protein, into their diets.

This study presents the first African pedogenic carbonate estimated atmospheric CO2 concentrations for the Early to Late Cretaceous transition. Pedogenic carbonates have been used extensively as proxies to reconstruct past climates, yet few studies have focused on the climatic conditions of Africa during the Mesozoic. The paucity of paleoclimate data from the region represents a significant obstacle in interpreting past climate change, and thus our ability to predict future changes. Paleosol carbonate nodules were sampled from Bk horizons of seven particularly well-exposed and well-characterized paleosols through the Cretaceous Galula Formation, including four from the lower Mtuka Member (Aptian -Cenomanian) and three from the upper Namba Member (Campanian). The Cretaceous Galula Formation is a fossiliferous continental sedimentary succession of braided fluvial deposits that are well exposed in recently incised river drainages of the Rukwa Rift Basin, Tanzania. Oxygen isotope values averaged-5.6 parts per thousand and-7.2 parts per thousand VPDB for the Mtuka and Namba members, equating to mean annual temperatures of 14.5 degrees C and 11.2 degrees C, respectively. Using the stable isotope composition of pedogenic carbonates from the Mtuka Member, an average pCO(2) of 1860 ppmv was estimated for the Aptian -Cenomanian, before declining to an average of 520 ppmv in the Namba Member, during the Campanian. Atmospheric pCO(2) values fluctuated, but remained above 1000 ppmv through the middle Cretaceous, and correspond to the "cool " greenhouse period that spanned the Aptian-Albian. The gradual decline in pCO(2) (550-502 ppmv) recorded in the Namba Member paleosols occurred during Late Cretaceous cooling following the Cretaceous Thermal Maximum. (c) 2022 Elsevier Ltd. All rights reserved.

Lake Barrine (17.25 degrees S, 145.64(degrees)E), on the Atherton Tablelands in tropical northeast Australia, was formed as a maar lake in the late Pleistocene. The 65 m-deep stratified lake provides a detailed sediment record of climate and environmental change on the Tablelands. We reconstruct hydroclimate and vegetation change over the last similar to 18,000 years from a 7.2 m long sediment core at 20-year resolution using multiple paleoenvironmental proxies (mu-XRF elements, delta C-13(TOC), TOC and C:N ratio). The data series are supported by a chronology based on 22 accelerator mass spectrometer (AMS) radiocarbon dates. The results suggest a distinct period of intense but highly seasonal rainfall coincident with the Antarctic Cold Reversal (14.7-13.0 cal ka BP). This period was followed by a trend into the early Holocene toward wetter, less seasonal conditions that allowed the progressive establishment of tropical forest in the catchment. The catchment was completely covered by closed forest by 7.3 cal ka BP. The inferred precipitation changes at Lake Barrine are consistent with other records on the Tablelands and in phase with the changes in tropical SE Africa, NW Australia and anti-phase with the East Asian summer monsoon region in the Holocene but not before that. This result supports previous conclusions that precipitation variations correlate (in phase or anti-phased) in these regions. This correlation results from a dynamic balance among intertropical convergence zone (ITCZ), the Indian Ocean Dipole (IOD) and El Nino Southern Oscillation (ENSO). (C) 2022 Elsevier Ltd. All rights reserved.

Insular Southeast Asia is of critical importance to global biodiversity, climate, and socioeconomics. Past environmental histories are a crucial factor influencing contemporary patterns and, in this region, fluctuating sea-level and climate change during the Last Glacial Period (LGP) resulted in drastic changes in both land extent and vegetation cover. However, understanding the past environments of this tropical region is hampered by its sheer size and relative lack of traditional continental proxy records, such as lake sediments. To provide further insight into the response of vegetation to the changing environmental conditions, we use the stable carbon isotope composition (delta C-13) of a bat guano sequence from Liang Mbelen Cave in North Sumatra, to determine whether tropical grass (C-4 vegetation) or forest (C-3 vegetation) was present in the area from c. 30 to 10 cal kyr BP. Our results confirm the presence of C-4 vegetation during the LGP; however, we find that the timing of grass expansion was just prior to the Last Glacial Maximum (LGM; 23-19 kyr BP). Comparing Liang Mbelen with the other evidence from across the region, we find a generally consistent pattern of peak tropical grasses often occurring prior to the LGM in Sundaland, with the timing of forest encroachment variable, although beginning at c. 25 cal kyr BP. We find that the timing of the shift from savanna to forest systems in Sundaland is similar to changes in obliquity, likely resulting in a decrease or elimination of the dry season that favoured forest expansion. Understanding past vegetation history will help the management and protection of the fragile and ecologically valuable ecosystems of SE Asia.

Pyrogenic carbon (charcoal, black carbon, elemental carbon) is one of the most common materials used for radiocarbon dating of terrestrial samples. However, exogenous carbon contamination can compromise the accuracy of radiocarbon ages. This study presents the results of two chemical pretreatments prior to hydrogen pyrolysis (hypy) as improved protocols for the isolation and decontamination of pyrogenic carbon, i) a simple acid-oxidation step (A-Ox/hypy) and ii) acid-base-acid (ABA/hypy). The A-Ox/hypy protocol uses HNO3 and H2O2, while ABA/hypy uses HCl and NaOH. Both pretreatments remove labile and inorganic carbon before hypy, decreasing the potential for in situ production of pyrogenic carbon during the hypy reaction. The effectiveness of each protocol was directly measured on charcoal artificially produced at 350 degrees C, 450 degrees C and 550 degrees C from radiocarbon-free wood, and exposed to environmental contamination for 1-3 yrs. The results show a 94% reduction in carbon contamination for the 450 degrees C and 550 degrees C charcoal samples occurred using A-Ox/hypy, but this treatment was less effective for the 350 degrees C charcoal. A >99% reduction in carbon contamination in all charcoal samples examined occurred using ABA/hypy. The A-Ox/hypy protocol was further tested on cave guano sediments, which had previously reported erroneous dates following simple organic solvent extraction followed by ABA pretreatment. Effective decontamination was achieved using A-Ox/hypy on the guano, which corrected a radiocarbon age reversal. Overall, ABA/hypy effectively decontaminated the charcoals and was a more efficient pretreatment for charcoal than A-Ox/hypy, however resulting in larger sample mass loss. Therefore, ABA/hypy is the recommended protocol for older (>30,000 C-14 yr BP) charcoal or sediment samples, or where date accuracy is imperative, while A-Ox/hypy represents an improved protocol for the quick and cost-effective measurement of younger samples (<30,000 C-14 yr BP) when sample size is of concern.

Quaternary Research is an international journal devoted to the advancement of the interdisciplinary understanding of the Quaternary Period.We aim to publish articles of broad interest with relevance to more than one discipline