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Dust is a major source of nutrients to remote ocean environments, influencing primary productivity (PP). Enhanced oceanic PP causes drawdown of atmospheric CO2 and is considered likely to be a driver of climate variability on glacial-interglacial timeframes. However, the scale of this relationship and its operation over shorter timescales remains uncertain, while it is unclear whether dust fertilisation, or other mechanisms, e.g. nutrient upwelling, are the primary driver of PP in high-nutrient low-chlorophyll (HNLC) ocean regions. In this study, we demonstrate, using dust derived Fe and Methanesulfonic acid (a measure of ocean PP) deposition in ice cores from the South Atlantic (South Georgia Island) and North Pacific (Yukon), that PP is significantly correlated with Dust-Fe on both an event and annual scale. However, measuring the relationship between (dust) Fe fertilization and PP in high resolution ice cores is subject to a number of highly complex factors, which are discussed and together used to recommend future research directions. In conclusion, our research suggests that changes in aeolian Fe flux, due to climate change and human activity in dust source regions, could have significant implications for HNLC ocean PP and, therefore potentially, carbon sequestration.

Anthropogenic landuse, principally agriculture, has been shown to result in increased dust emissions from susceptible environments in a number of discrete studies. However, until now, there has been no broad-scale assessment of changes in dust emissions associated with human activity. Earth's surface has undergone a vast transition associated with the conversion of wildlands to agricultural landscapes. This included development of semi-arid and arid landscapes, which are highly sensitive to wind erosion, for agriculture. Much of this change occurred in the period between the late 19th and mid-20th Centuries. Therefore, they occurred prior to the beginning of scientific investigation of Earth systems and widespread environmental concern. As a result, empirically quantifying changes to dust emissions is problematic due to a lack of data from this time period, and consequently, the impact of these changes has been underappreciated. However, sedimentary archives, such as ice cores, which record dust deposition, both before, and following widespread landuse change, allow the magnitude of anthropogenic dust emissions to be estimated. In this paper we present a global compilation of data from sedimentary archives that allow an assessment of the change in dust emissions driven by human activity. Results show that globally dust emissions increased by a factor of 2.1 times after the Industrial Revolution (1750 CE). This change coincides with the development of ‘industrial agriculture’ and the colonisation and development of new regions, e.g. Australia. Increases in anthropogenic dust are also shown by data compiled from other study types, such as remote sensing, airborne sediment sampling and meteorological station data. These additional studies, which don't predate the onset of industrial agriculture, and are more likely to be distorted by short term climate variability, suggest human activity has increased dust emissions by 1.3 to 45 times. Despite the uncertainties in these records and the limited number and spatial availably of sedimentary archive studies (n = 25), in combination they nevertheless imply that at least a doubling in dust emissions has occurred during the past ~250 years. The loss of soil associated with this change presents a serious challenge to soil security, while the increased dust load in the atmosphere is likely to have had a recognisable impact on biogeochemical cycles and climate. Consequently, the impact of changes both to, and from, global dust emissions warrants further investigation.

At present, knowledge of late Quaternary variability of the Indonesian-Australian summer monsoon in the Australian tropics is limited. Organic spring deposits, which occur throughout the Kimberley region of northwest Australia, are valuable archives that contain records spanning the past ∼14,500 years. In this study we compare multiple proxies from three organic springs. Principal Components Analyses demonstrates similar patterns of change in the elemental and non-pollen palynomorph (NPP) datasets between the springs, implying regional drivers are responsible for changes in these proxies. By comparison, the pollen records differ between each of the springs, with the assemblage at each thought to be influenced by spring recharge and evolution rather than climate variability. In order to empirically and objectively assess the synchronicity of changes, we applied Monte Carlo empirical orthogonal function (MCEOF) analysis to one variable in each μXRF and NPP dataset (Si/Ti ratios and Pseudoschizaea accumulation rates, as these proxies are expected to reflect hydrological conditions in springs) to assess regional patterns of change in site moisture. This analysis revealed periods of increased monsoonal precipitation from ∼14,500–7500 cal. yr BP corresponding with deglacial sea level rise, high orbital tilt coupled with warmer sea surface temperatures, and with possible links to a southward migration of the Inter Tropical Convergence Zone (ITCZ) during the Younger Dryas. Monsoonal precipitation was reduced from 7500 cal. yr BP coinciding with the culmination of deglacial sea level rise and a possible northward shift in the mean position of the ITCZ, in addition to between 2600 and 1000 cal. yr BP corresponding with increased moderate-to-strong ENSO events.

Swamps in the seasonal tropics have good potential for the reconstruction of late Quaternary monsoonal dynamics. Their successful use, however, has often been compromised by chronological limitations introduced by a variety of depositional and post-depositional processes actively modifying the swamp deposits. We here present and discuss the results of a multiple dating approach at Table Top Swamp (TTS) in northern Australia (the ‘Top End’). Single-grain luminescence dating of quartz was successfully used to provide chronology in the lowermost core where insufficient organic material prevents the application of radiocarbon dating. In the uppermost, fine-grained and peaty section of the core, two different organic fractions (pollen concentrate and humins) were dated with AMS radiocarbon yielding significantly different chronologies. While this could point to the incorporation of younger pollen into the profile along seasonal dry cracks, older humins may also move up in the profile due to vertical mixing. Additional, spatially highly resolved measurements of the bulk OSL signal (Ln and Ln/Tn) combined with data on down-core variation in K, Th, and U concentration, grain size and moisture content were used to (i) guide the development of an age-depth relationship (i.e. age model) for the entire core based on three different data input scenarios, and (ii) test the applicability of novel luminescence screening techniques in seasonal swamp settings. Results suggest only minor differences among the applied models and scenarios, providing an overall reliable representation of the depositional history in the swamp. Even though all resulting age-depth models have relatively large uncertainties in the lower part of the core, there are significant changes in sedimentation rate over time, providing a chronological basis for a more detailed palaeoenvironmental analysis at TTS. The approach used may also be useful in developing age models in other complex environments, and has shown the importance of understanding carbon pathways as well as controls on luminescence signals when developing age models.

Dust entrainment, transport over vast distances and subsequent deposition is a fundamental part of the Earth system. Yet the role and importance of dust has been underappreciated, due largely to challenges associated with recognising dust in the landscape and interpreting its depositional history. Despite these challenges, interest in dust is growing. Technical advances in remote sensing and modelling have improved understanding of dust sources and production, while advances in sedimentology, mineralogy and geochemistry (in particular) have allowed dust to be more easily distinguished within sedimentary deposits. This has facilitated the reconstruction of records of dust emissions through time. A key advance in our understanding of dust has occurred following the development of methods to geochemically provenance (fingerprint) dust to its source region. This ability has provided new information on dust transport pathways, as well as the reach and impact of dust. It has also expanded our understanding of the processes driving dust emissions over decadal to millennial timescales through linking dust deposits directly to source area conditions. Dust provenance studies have shown that dust emission, transport and deposition are highly sensitive to variability in climate. They also imply that dust emissions are not simply a function of the degree of aridity in source areas, but respond to a more complex array of conditions, including sediment availability. As well as recording natural variability, dust records are also shown to sensitively track the impact of human activity. This is reflected by both changing dust emission rates and changing dust chemistry. Specific examples of how dust responds to, and records change, are provided with our work on dust emissions from Australia, the most arid inhabited continent and the largest dust source in the Southern Hemisphere. These case studies show that Australian dust emissions reflect hydro-climate variability, with reorganisation of Australian dust source areas occurring during the mid to late Holocene. Dust emissions are shown to sensitively map the structure of the Last Glacial Maximum in Australia, demonstrating that this period was associated with enhanced, but also variable dust emissions, driven by changing sources area conditions. Finally we show how dust emissions have responded to the arrival of Europeans and the associated onset of broad-scale agriculture across the Australian continent.

Organic spring deposits have the potential to provide to outstanding records of palaeoenvironmental and climatic change, particularly in arid and semi-arid environments where establishing robust records of environmental change is challenging due to a lack of classic sedimentary records, e.g. perennial lakes and extensive wetlands. However, despite the potential of organic spring deposits a number of studies demonstrate complications in the application of standard 14C techniques which has, in several cases, led to confusing chronologies. This implies that dynamic carbon pathways commonly occur within spring systems. Because of the importance of springs as critical palaeoenvironmental archives, this study sought to better understand the behaviour of 14C and other radionuclides used in geochronology within organic springs, and ultimately, establish a protocol for building reliable chronologies in these environments. To do this, we utilised multiple geochronological methodologies to investigate cores collected from three springs in the Kimberley region of northwest Australia. This included 14C dating of different carbon fractions, 210Pb dating, the application of 239+240Pu, and novel, high spatial resolution, luminescence techniques as indicators of geochronological structure. The natural sensitivity-corrected luminescence (Ln/Tn) signal indicated the studied springs contained a relatively complete stratigraphic record, however 14C results were found to be convoluted by contamination attributed to a combination of roots, groundwater fluctuations and allochthonous input of “old” carbon affecting ages. Whilst it was found that no single carbon fraction is universally reliable in dynamic spring environments, dating the stable polycyclic aromatic carbon (SPAC), isolated by hydrogen pyrolysis (HyPy) pre-treatment, appeared to remove the effects of post-depositional modification which otherwise perturbed the age of carbon fractions with respect to sedimentary development of the spring. By contrast, the ability of 210Pb and 239+240Pu to provide detailed chronologies for recent spring sediments (i.e. the past 100 years) was found to be complicated due to the behaviour of springs as an open system with regards to uranium. Therefore, it may not be possible to construct 210Pb chronologies in many spring environments. Overall, the results of this study indicate that it is possible to construct 14C based chronologies in spring systems, however it is necessary to understand the effects of physical and biological processes within springs on 14C pathways. In particular, the application of HyPy pre-treatment of SPAC appears to offer a viable approach to constructing chronologies in these environments. Furthermore, although this study pertains to springs, the sources of geochronological complexity described here are not exclusive to these systems and our results are therefore more widely applicable.

The Indo-Australian Summer Monsoon (IASM) is the dominant climate feature of northern Australia, affecting rainfall/runoff patterns over a large portion of the continent and exerting a major control on the ecosystems of Australia's Top End, including the viability of wetland ecosystems and the structure of the woody savanna. We examined the behaviour the IASM from 35 kyr using proxy data preserved in the sediments of Table Top Swamp, a small seasonal swamp in northern Australia. Elemental data, stable C and N isotopes, pollen and sedimentary data were combined to develop a picture of monsoon activity and landscape and ecosystem response. Results demonstrated that between 35 and 25 ka conditions were drier and more stable than present, with a more grass dominated savanna and limited wetland development, implying reduced IASM activity. After ~25 ka, there is evidence of increased moisture at the study site, but also increased IASM variability. However, despite evidence of at least periodic increases in moisture, including periods of wetland establishment, the IASM displayed a subdued response to peak precession insolation forcing by comparison to the other global monsoon systems. Instead, the greatest change occurred from ~10 ka when the continental shelf flooded, increasing moisture advection to the study site and resulting in establishment of a quasi-permeant wetland. Whereas the early Holocene was marked by both the onset of pollen preservation and a wetter vegetation mosaic, indicative of a consistently active IASM, the mid-late Holocene was marked by drier vegetation, increased fire, but also increased C3 vegetation and runoff, implying increased IASM variability. Holocene changes in ecosystem dynamics occur coincident with an expansion in human population, which likely also influenced vegetation and landscape response at the study site.

Understanding of the late Quaternary environment of Australia's vast Kimberley region has to date been hindered by the region's lack of classic palaeoenvironmental archives such as deep lake sediments. However, mound spring peat deposits in the region have been found to be a potentially rich archive of palaeoenvironmental data. Here we present a high resolution record from Black Springs mound spring in the Kimberley's northwest, filling some of the current gaps in knowledge of the region's environmental history. This builds on a ∼6000 year record developed from the same site and indicates that since the Last Glacial-Interglacial Transition the Australian summer monsoon has varied greatly in intensity, with an increase in monsoonal precipitation from ∼14,000 yr BP and pronounced drying in the late Holocene. Despite some chronological uncertainties thought to be due to the inclusion of younger, microscopic root fragments, changes in the record compare well with other records of climatic change from the Kimberley, and across tropical northern Australia.

The widespread formation of organic rich sediments in south-east Australia during the Holocene (Marine Isotope Stage [MIS] 1) reflects the return of wetter and warmer climates following the Last Glacial Maximum (LGM). Yet, little is known about whether a similar event occurred in the region during the previous interglacial (MIS 5e). A 6.8 m sediment core (#LC2) from the now ephemeral Lake Couridjah, Greater Blue Mountains World Heritage Area, Australia, provides insight into this question. Organic rich sediments associated with both MIS 1 and 5e are identified using 14C and optically stimulated luminescence (OSL) dating techniques. Also apparent are less organic sedimentary units representing MIS 6, 5d and 2 and a large depositional hiatus. Sediment δ13C values (−34 to −26‰) suggests that C3 vegetation dominates the organic matter source through the entire sequence. The pollen record highlights the prevalence of sclerophyll trees and shrubs, with local hydrological changes driving variations in the abundance of aquatic and lake-margin species. The upper Holocene sediment (0–1.7 m) is rich in organic matter, including high concentrations of total organic carbon (TOC; 20–40%), fine charcoal and macrophyte remains. These sediments are also characterised by a large proportion of epiphytic diatoms and a substantial biogenic component (chironomids and midges). These attributes, combined with low δ13C and δ15N values, and C:N ratios of approximately 20, indicate a stable peat system in a swamp like setting, under the modern/Holocene climate. In comparison, the lower organic rich unit (MIS 5e-d) has less TOC (5–10%), is relatively higher in δ13C and δ15N, and is devoid of macrophyte remains and biogenic material. Characterisation of the organic matter pool using 13C-NMR spectroscopy identified a strong decomposition signal in the MIS 5e organic sediments relative to MIS 1. Thus the observed shifts in δ13C, δ15N and C:N data between the two periods reflects changes in the organic matter pool, driven by decompositional processes, rather than environmental conditions. Despite this, high proportions of aquatic pollen taxa and planktonic diatoms in the MIS 5e–d deposits, and their absence in the Holocene indicates that last interglacial Lake Couridjah was deeper and, or, had more permanent water, than the current one.

Soil production in actively uplifting or high precipitation alpine landscapes is potentially rapid. However, these same landscapes are also susceptible to erosion and can be sensitive to changes in climate and anthropogenic activity which can upset the balance between soil production and erosion. The Snowy Mountains, southeastern Australia, are a tectonically stable, low relief, moderate precipitation mountain environment. The alpine area is extensively blanketed by soil that has been subjected to more intensive episodes of erosion during past periods of anthropogenic disturbance and under cold climate conditions of the late Quaternary. In this study, rates of soil development and hillslope erosion were investigated using radiocarbon dating, fallout radionuclides and sediment cores collected from lakes and reservoirs. Estimated Holocene soil development rates were 20-220 t/km/y. Erosion rates determined from the radionuclides Cs and Pb were equivocal, due to the inherent spatial variability of radionuclide inventories relative to apparent erosion rates. Estimated average erosion rates over the past 100 years, determined from Pb inventories, were 60 t/km/y (95% CI: 10, 90). Inventories of Cs observed at the same site implied that more recent erosion rates (over the past 60 years) was below the detection limits of the sampling method applied here (i.e.

This study examines mangrove substrate production within a mangrove basin forest in the Tweed Estuary, northern New South Wales, Australia. This is achieved using high resolution dating of 239+240Pu, 236U and 210Pb in mangrove sediments to examine both the modes and rates of mangrove substrate production. Results show a shift in the mode of substrate production occurred approximately 70 years ago in response to human modification of the Tweed Estuary (hydrologic changes). At that time, mangrove substrate production shifted from being dominated by sedimentation processes (fine silt accumulation) to being dominated by biological processes (mangrove root production). Since that time, mangrove peat has been accreting at the study site at the same rate as local sea level rise (SLR), implying current rates of peat substrate development are tuned to increasing sea level. A further implication of the shift to biological accretion at rates corresponding with SLR is that the studied mangrove basin is sequestering C at increasing rates due to subsurface root production.

Industrial metals are now ubiquitous within the atmosphere and their deposition represents a potential source of contamination to surficial environments. Few studies, however, have examined the environmental fate of atmospheric industrial metals within different surface environments. In this study, patterns of accumulation of atmospherically transported industrial metals were investigated within the surface environments of the Snowy Mountains, Australia. Metals, including Pb, Sb, Cr and Mo, were enriched in aerosols collected in the Snowy Mountains by 3.5-50 times pre-industrial concentrations. In sedimentary environments (soils, lakes and reservoirs) metals showed varying degrees of enrichment. Differences were attributed to the relative degree of atmospheric input, metal sensitivity to enrichment, catchment area and metal behaviour following deposition. In settings where atmospheric deposition dominated (ombrotrophic peat mires in the upper parts of catchments), metal enrichment patterns most closely resembled those in collected aerosols. However, even in these environments significant dilution (by 5-7 times) occurred. The most sensitive industrial metals (those with the lowest natural concentration; Cd, Ag, Sb and Mo) were enriched throughout the studied environments. However, in alpine tarn-lakes no other metals were enriched, due to the dilution of pollutant-metals by catchment derived sediment. In reservoirs, which were located lower within catchments, industrial metals exhibited more complex patterns. Particle reactive metals (e.g. Pb) displayed little enrichment, implying that they were retained up catchment, whereas more soluble metals (e.g., Cu and Zn) showed evidence of concentration. These same metals (Cu and Zn) were depleted in soils, implying that they are preferentially transported through catchments. Enrichment of other metals (e.g. Cd) varied between reservoirs as a function of contributing catchment area. Overall this study showed that the fate of atmospherically derived metals is complex, and depends upon metal behaviour and geomorphic processes operating at landscape scales.

Atmospheric aerosol samples were collected at a remote site in New Zealand's Southern Alps. Collected samples were found to be a mixture of New Zealand and Australian sourced sediment, using their trace element signatures. Aerosol concentrations and the relative contribution of different sources was found to be a function of specific air-mass trajectories influencing the study site, dust entrainment rates in source areas and rainfall. Results show that Australian dust is a major source of particulate matter in New Zealand, particularly in remote alpine locations; however, locally derived dust is also important. Metal pollutants, including Pb, Cu and Sn, were enriched in the samples by approximately 15 times and up to >100 times expected natural concentrations, confirming that metal pollution is a ubiquitous component of the atmosphere, even in relatively remote locations. Moreover, pollutants were highly enriched in otherwise clean air, i.e. during and following rainfall. Additionally, high concentrations of elements naturally enriched in sea water, e.g. Sr, Ba and Rb, were deposited alongside mineral dust, reflecting the oceanic origin of air influencing the site and the role of sea spray in contributing aerosol to the atmosphere. These elements experienced the greatest enrichment during rainfall, implying sea spray and pollution become relatively important during otherwise clean air conditions.

Millennial scale variability in the strength/position of the mid-latitude westerlies, as interpreted from rates of dust deposition in an alpine mire south-eastern Australia, is demonstrated to be a major driver of climate variability during the mid to late Holocene. Dust deposition rates were calculated with a trace element provenance model. This approach is capable of distinguishing between sedimentation of local alluvium and genuine deposition of aeolian dust into the studied mire. Low dust deposition from 6500 to 5500 cal. BP occurred during a period of enhanced south-westerly winds which advected moisture into south-eastern Australia resulting in wet conditions. A subsequent dust pulse at 5500-4000 cal. BP is interpreted as a relaxation in south-westerlies resulting in a more arid phase and possibly enhanced climate variability. Reduced dust deposition between 4000 and 2000 cal. BP indicates a return to increased precipitation/moisture in the lower MDB associated with increased south-westerly geostrophic flow. The onset of more arid conditions after 2000 cal. BP implies a reduction in the frequency of precipitation bearing south-westerly winds. A final further significant finding from this study is the identification of a major dust deposition/wind erosion episode coinciding with the onset of European land clearing and agriculture in Australia.

A recent paper by De Deckker et al. (2010; Lead isotopic evidence for an Australian source of Aeolian dust to Antarctica at times over the last 170,000 years, Palaeogeography, Palaeoclimatology, Palaeoecology, 285(3-4), 205-223) reports radiogenic isotope data of fluvial sediment samples from the Murray Darling Basin (MDB) in southeastern Australia. Some of these display Pb-isotope ratios similar to ancient, pre-industrial pollution dust retrieved from the EPICA Dome C ice core, Antarctica. The authors proposed that this result supports a dust provenance from the Darling sub-basin of the MDB. De Deckker et al. (2010) apparently did not appreciate the extent of anthropogenic Pb contamination of their potential Australian dust sources. In addition, they also neglected to analyze many of the other important Australian dust sources. By contrast, it is demonstrated here that the surface sediments are severely polluted, that other potential dust sources from Australia also need to be considered and that it is not possible to unequivocally distinguish Australian from South American dust using Pb-isotopes alone. (C) 2010 Elsevier B.V. All rights reserved.

A high-resolution dataset of trace element concentrations is presented for the Murray-Darling Basin, Australia, Australia's most important river system. The data were obtained by solution quadrupole ICP-MS resulting in concentrations for 44 elements. Of these, 21 were determined with a long-term external precision of better than 1% and a further 13 at a precision better than 2%. Trace element maps for the surface sediments constructed from such high precision data reveal small but coherent variations in the four major sub-catchments of the basin, even in ratios of elements with very similar geochemical behaviour, such as Y/Ho, Nb/Ta and Zr/Hf. The origin of these chemical fingerprints of drainage systems are discussed in terms of the geochemical character of the upper continental crust. The potential of trace element maps for palaeo-environmental and climatic reconstruction is then illustrated. First, a sample of dust collected in a trap located in the far southeastern corner of the study area is used to pinpoint the location of the dust source. Next the fine-scale change in down-stream alluvial sediment chemistry is analysed to estimate the importance of sediment contribution from tributaries with a view to reconstructing river flow dynamics. Finally, the chemistry of dune sediments is compared with surrounding floodplain alluvium to estimate relative age of deposition. These examples demonstrate that in low-elevation river systems, such as the Murray-Darling Basin, extended trace element maps of sediment offer substantially more applications than radiogenic isotope data alone.

Investigating past human-environment interactions requires not only suitable environmental proxies and well-dated archaeological records, but also a uniform temporal resolution between the two. In the arid interior of Australia, the archaeological record of human occupation is known only from relatively few locations, and palaeoenvironmental records with resolution on timescales akin to human lifetimes are rare. Even where detailed archaeological and palaeoenvironmental studies have been undertaken concurrently, it has proven difficult to match the temporal resolution of both the archaeological and sedimentary records. One approach is to make use of the extensive surface archaeological record and match it to high-resolution palaeoenvironmental records from elsewhere. Here, we utilise radiocarbon age determinations on charcoal from the deflated remains of heat retainer hearths from surface archaeological contexts in western NSW. Correlations with two different but related sets of environmental proxy data (sea surface temperature fluctuations from the western Pacific/South China Sea and Australian dust deposition records from southern New Zealand) allow investigation of human responses to global environmental changes at a common temporal scale. The correlations suggest a relationship between rapid climatic changes occurring over the last 3000 years and occupation by Aboriginal people in the arid region of western New South Wales. Aboriginal people abandoned large regions during times of lower rainfall and increased dust transport, with some but not all regions reoccupied during periods of increased summer rainfall. Environmental fluctuations during the late Holocene are likely to have posed marked challenges for Aboriginal populations who occupied the region. The patterns of radiocarbon assays from hearths provide a window into the nature of their response.

Two peat bogs from remote alpine sites in Australia were found to contain detailed and coherent histories of atmospheric metal pollution for Pb, Zn, Cu, Mo, Ag, As, Cd, Sb, Zn, In, Cr, Ni, Tl and V. Dramatic increases in metal deposition in the post-1850 AD portion of the cores coincide with the onset of mining in Australia. Using both Pb isotopes and metals, pollutants were ascribed to the main atmospheric pollution emitting sources in Australia, namely mining and smelting, coal combustion and agriculture. Results imply mining and metal production are the major source of atmospheric metal pollution, although coal combustion may account for up to 30% of metal pollutants. A novel finding of this study is the increase in the otherwise near-constant Y/Ho ratio after 1900 AD. We link this change to widespread and increased application of marine phosphate fertiliser in Australia's main agricultural area (the Murray Darling Basin).

We report rates of Australian dust deposition in New Zealand over the last ~ 8000 years using records extracted from an ombrotrophic peat bog. The trace element chemistry of deposited dust is used to identify the Australian source areas, and to calculate Australian dust deposition rates in New Zealand. This is used to infer patterns of aridity and climate variability in eastern Australia during the Holocene. Prior to 4800 cal. BP, dust deposition patterns imply that the Australian climate was relatively wet due to an active/persistent monsoon. Southern Australian source regions supplied the majority of dust transported to New Zealand at this time. After 4800 cal. BP the Australian climate became significantly more arid and variable, attributed to the onset of ENSO-type conditions. The Lake Eyre Basin switched on as a dust source, while overall Australian dust deposition in New Zealand increased > 4 times. Rates of Australian dust deposition were found to match patterns of increased ENSO variability, which is attributed to the combined effect of enhanced sediment supply to Australian dust source areas (during wet La Nina events) and preferable conditions for dust transport (during El Nino induced drought). Results also show that Australian dust deposition is a significant sedimentary process in New Zealand and is likely to influence both geochemical cycles and soil development suggesting that it may contribute up to 90% of material in the bog.

Dust samples collected from the surface of glaciers and in dust traps on the remote West Coast of New Zealand's South Island can reliably be identified as being of both Australian and New Zealand origin. Most are, however, found to be enriched in Cu, Zn, Cd, Sb, Sn, Pb, Ni and Cr, when compared with their source-area sediments. The degree of metal enrichment in the dust samples is proportionally related to the percentage of Australian dust implying that the pollutants were transported with dust from eastern Australia. Pollution enrichment factors for these metals in dusts were calculated with a high degree of certainty, because the specific source regions of the dust could be identified. Rates of trace metal pollution transport were then calculated using a record of Australian dust transport over New Zealand. Results show that significant concentrations of trace metal pollutants are transported to New Zealand at levels that are between 1.5 and 100 times background conditions. Results also show that Sb, Pb and Cr are highly particle reactive and their transport in this region is almost exclusively associated with dust scavenging (up-take of pollutants by dust). By comparison, Cu, Zn, Cd, Sn and Ni may also be transported independently of dust. While the rates of pollution metal transport reported here are lower than in more industrialised regions of the globe, the majority of these metals are being deposited in a region internationally recognised for its environmental and conservation values.

Weekly average atmospheric 210 Pb flux data collected between March 1989 and February 2001 are used to construct a record of Australian dust incursions onto the west coast, South Island, New Zealand. Dusts collected from New Zealand glaciers were found to contain a mixture of local New Zealand and long range Australian material, based on novel binary and tertiary mixing models of their ultra trace element chemistries. Trace element characteristics further allowed determination of the provenance of the long range dust component within Australia to better than 200 km resolution. 210 Pb analyses of these chemically characterised dust samples show that activity is related to the percentage of Australian dust in a linear fashion. However, 210 Pb activity of Australian dusts collected in New Zealand is orders of magnitude greater than that measured in the alluvial sediments of the provenance areas. Australian dusts collected in New Zealand are also highly enriched in 210 Pb compared to dusts collected in Australia. This shows that dust scavenges atmospheric 210 Pb which can therefore be used as an effective tracer of long range dust transport. Previously obtained average atmospheric 210 Pb flux data can thus be converted into the first record of long range Australian dust flux in New Zealand. Results show that the average atmospheric concentration of Australian dust in New Zealand is 5.3 μg m − 3 . There is a clear seasonality with the highest concentrations occurring in autumn–winter, preceding Australia's major dust storm season, which occurs in winter–spring. We propose that while meteorological factors control the occurrence of major dust storms, the availability of sediment in source areas is a major control on Australian dust flux in New Zealand. Dust flux is greatest after seasonal river flows when transport of extremely fine grained dust occurs. This is followed by transport of larger particles in the more spectacular winter–spring dust storms. Our results provide information on the characteristics and seasonality of dust transport in the Australian region, which had previously been difficult to quantify by other methods (e.g., satellite imagery). Results also attest to the effectiveness of 210 Pb as a tracer in this region.

On 7 February 2000 an atypical orange discolouration of snowfields in the central Southern Alps, New Zealand occurred following the passage of a cold front. Analysis of snow samples identified fine orangey-brown dust mixed with much coarser grey dust. Air parcel forward trajectories from dust sources in southern and central Australia, where dust storms were reported on 4 February 2000, were computed to identify the deposits source. Geochemical analyses of the dust deposit using 26 trace elements, unaffected by regional air pollution and gravitational sorting, indicate that 20% of the dust was sourced from western New South Wales, with 45% from the eastern Eyre Peninsula of South Australia and the remaining 35% was local New Zealand dust. This provenancing approach provides a spatial resolution of long travelled dust sourcing not previously achieved.

Contemporary rates of dust deposition monitored along a 300-km section of the superhumid West Coast of New Zealand's South Island are presented. In this setting, dust is entrained primarily from the dry channels of braided glaciofluvial rivers that drain the western slopes of the Southern Alps. Measured dust deposition ranged between 0.21 and 118.9 kg−1 ha−1 month−1, which is similar to dust deposition rates monitored in arid and semiarid environments. However, these are not considered to be sufficient for present day loess genesis. Dust deposition was highest in summer because of the greater frequency of favourable dust transporting winds, and the effect of rainfall was secondary. Dust transportation occurred mainly during the passage of nonprecipitating cold fronts or postfrontal southwesterlies. Transportation also occurred during prefrontal conditions, and in winter fohn southeasterlies were the predominant dust transporting winds to affect the West Coast.