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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.

Reworking of old sediment in the Murray-Darling implies alteration of environmental signals traveling from source to sink., Understanding how sediment transport and storage will delay, attenuate, and even erase the erosional signal of tectonic and climatic forcings has bearing on our ability to read and interpret the geologic record effectively. Here, we estimate sediment transit times in Australia’s largest river system, the Murray-Darling basin, by measuring downstream changes in cosmogenic 26Al/10Be/14C ratios in modern river sediment. Results show that the sediments have experienced multiple episodes of burial and reexposure, with cumulative lag times exceeding 1 Ma in the downstream reaches of the Murray and Darling rivers. Combined with low sediment supply rates and old sediment blanketing the landscape, we posit that sediment recycling in the Murray-Darling is an important and ongoing process that will substantially delay and alter signals of external environmental forcing transmitted from the sediment’s hinterland.

International audience; A recent paper by Miszczak et al. (2020) examines metal contamination of mires in Poland and Norway. The authors conclude that lead (Pb) records in ombrotrophic peatlands cannot be used to reconstruct the chronological history of anthropogenic activities due to post-depositional mobility of the metal. We contest this general conclusion which stands in contrast with a significant body of literature demonstrating that Pb is largely immobile in the vast majority of ombrotrophic peatlands. Our aim is to reaffirm the crucial contribution that peat records have Science of the Total Environment xxx (xxxx) xxx ⁎ Corresponding author at: Instituto Franco-Argentino para el Estudio del Clima y sus Impactos (j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / s c i t o t e n v made to our knowledge of atmospheric Pb contamination. In addition, we reiterate the necessity of following established protocols to produce reliable records of anthropogenic Pb contamination in environmental archives.

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.

Management of coastal wetlands is increasingly difficult because of increasing pressure arising from anthropogenic causes. These include sea level and climate change as well as coastline development caused by population growth and demographic shifts, for example, amenity migration where people move to coastal communities for lifestyle reasons. Management of mangroves and salt marshes is especially difficult because maintaining ecosystem values, including the goods and services provided, is countered by the potential of enhancing or even creating ecosystem disservices, such as unpleasant odour and mosquito hazards. Here we present, explain and apply a conceptual model aimed at improving understanding of management choices that primarily focus on mitigation of disservice while enabling improvement in ecosystem services. The model was developed after more than 30 years of habitat management following modification of a salt marsh to control mosquito production. We discuss the application of the model in a mangrove forest known to produce mosquitoes and outline the benefits arising from using the model.

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.

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.

Australia, the last continent to undergo industrial development, is an ideal environment in which to quantify the magnitude of human-induced environmental change during the Anthropocene because its entire agricultural and industrial history has occurred within this period. Analysis of an alpine peat mire showed that rapid industrial and agricultural development (both pastoral and cropping) over the past 200 years has resulted in significant environmental change in Australia. Beginning in the 1880s, rates of wind erosion and metal enrichment were up to 10 and 30 times that of background natural conditions, respectively. Increased dust deposition and an expansion in dust source areas were found to map the progression of European farming across the continent, while dust deposition pulses in the mire matched known land degradation events. After 1990 dust deposition decreased, returning to pre-1880 rates. This was attributed to three factors: net soil loss following more than a century of agricultural activity, increased environmental awareness and soil conservation, and changing windiness. Metal enrichment in the mire reached approximately 2 times natural background accumulation rates by the 1980s as Australia's mining industry expanded. However, metal enrichment continued to increase after the 1980s reaching an average of ~5 times background rates by 2006 and reflecting increased mineral resource development in Australia. Collectively, the results show that changes to Australia's geochemical and sedimentary systems, as a result of agricultural and industrial development, have profoundly changed the Australian environment during the past two centuries. Key Points The 2.5 up increase in wind erosion since agricultural development Average of 5 times increase in metal enrichment since 1880 Two phases of the Anthropocene are identifiable

Soil carbon stores amount to 54% of the terrestrial carbon pool and twice the atmospheric carbon pool, but soil organic carbon (SOC) can be transient. There is an ongoing debate about whether soils are a net source or sink of carbon, and understanding the role of aeolian processes in SOC erosion, transport and deposition is rudimentary. The impacts of SOC erosion by wind on the global carbon budget, and its importance for carbon accounting remain largely unknown. Current understanding of SOC losses to wind erosion is based on the assumption that the SOC content of eroded material is the same as that of the parent soils. However, measured enrichment factors for the SOC content of Australian dusts relative to parent soils show that the SOC content of dusts can be up to seven times (by weight) larger than that of source-area soils, with enrichment factors ranging from 1.67 to 7.09. Assuming dust emissions from the continent of ~110 Mt yr 1 , SOC dust emissions would be 0.13–4.65 Mt SOC yr 1 without enrichment but 0.94–7.77 Mt SOC yr 1 with enrichment; which represents an uncertainty of around 60%. Representing SOC enrichment within dust emission models will reduce uncertainty in estimates of the impact of wind erosion on SOC flux and provide an approach for the inclusion of wind erosion processes in carbon accounting systems.

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).

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.

During the past two centuries metal loads in the Earth's atmosphere and ecosystems have increased significantly over pre-industrial levels. This has been associated with deleterious effects to ecosystem processes and human health. The magnitude of this toxic metal burden, as well as the spatial and temporal patterns of metal enrichment, is recorded in sedimentary archives across the globe. This paper presents a compilation of selected Pb contamination records from lakes (n = 10), peat mires (n = 10) and ice fields (n = 7) from Europe, North and South America, Asia, Australia and the Northern and Southern Hemisphere polar regions. These records quantify changes in Pb enrichment in remote from source environments. The presence of anthropogenic Pb in the environment has a long history, extending as far back as the early to mid-Holocene in North America, Europe and East Asia. However, results show that Pb contamination in the Earth's environment became globally ubiquitous at the beginning of the Second Industrial Revolution (c.1850–1890 CE), after which the magnitude of Pb contamination increased significantly. This date therefore serves as an effective global marker for the onset of the Anthropocene. Current global average Pb enrichment rates are between 6 and 35 times background, however Pb contamination loads are spatially variable. For example, they are >100 times background in Europe and North America and 5–15 times background in Antarctica. Despite a recent decline in Pb loads in some regions, most notably Europe and North America, anthropogenic Pb remains highly enriched and universally present in global ecosystems, while concentrations are increasing in some regions (Australia, Asia and parts of South America and Antarctica). There is, however, a paucity of Pb enrichment records outside of Europe, which limits assessments of global contamination.

Soil and sediment samples from the Sydney basin were measured to ascertain fallout radionuclide activity concentrations and atom ratios. Caesium-137 ((137)Cs) was measured using gamma spectroscopy, and plutonium isotopes ((239)Pu and (240)Pu) were quantified using accelerator mass spectrometry (AMS). Fallout radionuclide activity concentrations were variable ranging from 0.6 to 26.1 Bq/kg for (137)Cs and 0.02-0.52 Bq/kg for (239+240)Pu. Radionuclides in creek sediment samples were an order of magnitude lower than in soils. (137)Cs and (239+240)Pu activity concentration in soils were well correlated (r(2) = 0.80) although some deviation was observed in samples collected at higher elevations. Soil ratios of (137)Cs/(239+240)Pu (decay corrected to 1/1/2014) ranged from 11.5 to 52.1 (average = 37.0 ± 12.4) and showed more variability than previous studies. (240)Pu/(239)Pu atom ratios ranged from 0.117 to 0.165 with an average of 0.146 (±0.013) and an error weighted mean of 0.138 (±0.001). These ratios are lower than a previously reported ratio for Sydney, and lower than the global average. However, these ratios are similar to those reported for other sites within Australia that are located away from former weapons testing sites and indicate that atom ratio measurements from other parts of the world are unlikely to be applicable to the Australian context.

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.

The Kimberley region of northwest Australia contains one of the World's largest collections of rock art characterised by two distinct art forms; the fine featured anthropomorphic figures of the Gwion Gwion or Bradshaw paintings, and broad stroke Wandjina figures. Luminescence dating of mud wasp nests overlying Gwion Gwion paintings has confirmed an age of at least 17,000 yrs B.P. with the most recent dates for these paintings from around the mid-Holocene (5000 to 7000 yrs B.P.). Radiocarbon dating indicates that the Wandjina rock art then emerged around 3800 to 4000 yrs B.P. following a hiatus of at least 1200 yrs. Here we show that a mid-Holocene ENSO forced collapse of the Australian summer monsoon and ensuing mega-drought spanning approximately 1500 yrs was the likely catalyst of this change in rock art. The severity of the drought we believe was enhanced through positive feedbacks triggered by change in land surface condition and increased aerosol loading of the atmosphere leading to a weakening or failure of monsoon rains. This confirms that pre-historic aboriginal cultures experienced catastrophic upheaval due to rapid natural climate variability and that current abundant seasonal water supplies may fail again if significant change in ENSO occurs.

This study analyses 1800 years of heavy metal accumulation in a remote alpine lake experiencing long-range atmospheric contamination and additional inputs of Ag from cloud seeding. In comparison to previous work undertaken on peats, lake sediments show limited post-industrial metal enrichment with enrichment factors of Ag: 1.3, Pb: 1.3, Zn: 1.1, Cu: 1.2 compared to Ag: 2.2, Pb: 3.3, Zn: 2.1, Cu: 4.1 for peat. We show this to be the result of substantial fluvial lithogenic flux of metals (92–97% of total metal flux) to the lake. Total annual metal flux to the lake ranges from: Ag: 4–12 ng/cm2/yr to Zn: 3 383–11 313 ng/cm2/yr. As a result, any contribution of cloud seeding to additional enrichment of Ag in lake sediments is considered negligible. Results show that metal enrichment is not necessarily ubiquitous through a landscape. This has implications for predicting the impacts of atmospheric metal pollution to complex environmental systems.

Evidence of solar and tropical-ocean forcing of climate cycles has been found in numerous palaeoclimate records. Numerical modelling studies show physical mechanisms by which direct and indirect solar forcing may affect climate, while there is mounting evidence of solar forcing of tropical ocean-atmosphere teleconnections. This study has developed a 6500 year record of dust deposition, a proxy for regional hydroclimate variability for the Snowy Mountains region of Australia. Spectral analysis of the record provides evidence of statistically significant cycles in dust deposition of 35–43 years, 62–73 years, 161 years and 2200 years. These correlate with variability in solar irradiance and the Pacific Decadal Oscillation (PDO). We present evidence to support physical links between variability in solar irradiance and change in the hydroclimate of southeast Australia and suggest that the effects of global warming and solar maxima on atmospheric circulation over extra-tropical regions may exacerbate these impacts.

Full-text is free to read on publisher website. The Pacific Decadal Oscillation (PDO) is a major forcing of inter-decadal to quasi-centennial variability of the hydroclimatology of the Pacific Basin. Its effects are most pronounced in the extra-tropical regions, while it modulates the El NiA±o Southern Oscillation (ENSO), the largest forcing of global inter-annual climate variability. PalaeoPDO indices are now available for at least the past 500 years. Here we show that the >500 year PDO index of Shen et al. (2006) is highly correlated with inflows to the headwaters of Australia's longest river system, the Murray-Darling. We then use the PDO to reconstruct annual inflows to the Murray River back to A.D. 1474. These show penta-decadal and quasi-centennial cycles of low inflows and a possible 500 year cycle of much greater inflow variability. Superimposed on this is the likely influence of recent anthropogenic global warming. We believe this may explain the exceptionally low inflows of the past decade, the lowest of the previous 529 years. Copyright 2009 by the American Geophysical Union.