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Runnelling is a minor and successful form of open marsh water management developed in Australia in the 1980s and integrated into mosquito control programs in the 1990s. While long-term monitoring and investigation of impacts has continued for one site, until recently there has been no assessment of operational runnelling more broadly across mosquito control agencies. This study addresses this issue. Forty-seven runnelled saltmarsh sites were assessed for runnel efficacy, function and condition. Issues impacting on runnel function, including both ecological and geomorphic processes, were noted. Data were mostly acquired from site inspections and discussions with mosquito control staff, with some records as available. Most runnels were constructed between 1990 and 2005, mainly using a dedicated runnelling machine. Almost half (49%) continued to contribute to mosquito control efficacy, either in part or fully, while half did not (51%). Efficacy was attributed to runnels being correctly configured in design, layout and construction and to relatively recent maintenance. Conversely, diminished efficacy was mostly attributed to ineffective hydrologic function, caused by vegetation blockages, erosion and/or deposition. Runnels alter tidal hydrology, affecting other ecological and geomorphic processes. These processes need to be managed to maintain runnel function and it is essential that monitoring and maintenance records are kept. Runnels can control mosquitoes for decades, provided ongoing monitoring and maintenance of the runnel system focusses on responding to early signs of impacts. Restoring degraded runnels should be undertaken using a runnel machine, however, changing environmental conditions may mean that a runnel should be ‘decommissioned’ instead.

The Puna-Altiplano plateau represents a regionally significant dust source, which is critically located at the nexus between the tropical and sub-polar synoptic systems that dominate the South American climate. Dust emissions in this region would therefore be expected to be sensitive to changes in these systems, in particular the strength and position of the South American Summer Monsoon (SASM). Here, we present a late-Holocene multi-proxy study where changes in dust flux, reconstructed from a high-altitude peat mire, are examined in light of climate variability and human impacts. Results show that for most the 4300 cal. yr BP record, dust flux sensitively tracked changes in SASM activity. Prior to 2600 cal. yr BP relatively high dust flux implies dry conditions prevailed across the Puna-Altiplao in association with reduced SASM activity. The chemistry of dust deposited at this time matched the large endorheic basins on the Puna, which host ephemeral lakes and terminal fans, indicating these were actively supplying dust to the airstream. After 2600 cal. yr BP, SASM activity increased while dust flux decreased and the dust chemistry changed, collectively implying the shutting down of the Puna-Altiplano as a significant dust source. Dust flux increased after 1000 cal. yr BP during the ‘Medieval Warm Period’, associated with a return to drier conditions and reactivation of dust sources across the endorheic basins of the Puna. Natural variability in dust flux was dwarfed, however, by the very significant increase in flux after 400 cal. yr BP following Spanish Colonisation and associated changing landuse practices. This finding attests to the globally significant role of humans on dust emissions.

Soil Organic Carbon (SOC) represents with up to 80% the largest part of the terrestrial’s carbon pool. However, it is still highly debated if soil-carbon is a net atmospheric carbon source or sink. This is mainly due to a paucity of information on the SOC’s fate during soil erosion, which controls the interplay between SOC oxidation during soil storage, transportation, and final storage in a sedimentary sink. The southern hemisphere landmasses have the potential to play a dominant role in the SOC - atmosphere carbon cycle, since wetter (dryer) climates can cause the expansion (contraction) of terrestrial biomass in vast continental areas, such as for example in temperate to semi-arid SE Australia.We herein investigate the interplay between catchment erosion (quantified by means of uranium isotopes), vegetation density (pollen), the wetland’s response (diatoms), and catchment-wide carbon and nitrogen cycling (carbon and nitrogen isotopes) on glacial/interglacial time scales in SE Australia. The analyses are applied to the sediments of Lake Couridjah, which is part of the Thirlmere Lake system located approximately 100 km SE of Sydney. A previous study has shown that Lake Couridjah and its catchment vegetation are highly sensitive to local and regional climate change. Radiocarbon and luminescence dating revealed that recovered lake sediments cover the time interval between ~140 ka and 100 ka, and between ~17.6 cal yr BP and present day. Lake Couridjah is thus one of the very few sedimentary archives providing a continuous archive for the previous interglacial complex in SE Australia, and thus offers an outstanding opportunity to study SOC cycling in a small catchment across different interglacial boundary conditions. The sedimentary analyses are supported by uranium, carbon, and nitrogen isotope analyses of a soil pit from the vicinity of the lake.Statistical analyses revealed robust phase-relationships between catchment erosion, vegetation density, and carbon and nitrogen cycling during both glacial-interglacial complexes. The data implies that the density of the catchment’s sclerophyll woodland and mid- to understory vegetation - and not the amount of rainfall - has major control on catchment erosion, and, thus, on SOC storage in the catchment. Overall wetter and warmer peak interglacial conditions promote the expansion of dense sclerophyll vegetation, reducing catchment erosion while simultaneously increasing SOC storage as well as lake productivity and lake carbon-storage. The later post-Eemian phase of the preceding interglacial reveals overall cooler climates and a more open sclerophyll vegetation, resulting in faster catchment-wide erosion and reduced SOC and lake-C storage, conditions that are amplified in glacial periods (post-LGM, penultimate glacial period).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.