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A50–70 cm sea-level fall around A.D. 1300 may have led to a prolonged food crisis which caused conflict among coastal dwellers on high Pacific islands. The conflict may have necessitated abandoning difficult to defend coastal settlements and establishing ones in fortifiable locations inland. To test this idea, abandoned hillforts (koronivalu) on20km Yadua Island were studied. Yadua Island is 20 km off the western extremity of Vanua Levu Island, the second largest island in the Fiji archipelago, where many such hillforts once existed. Human-made structures (stone walls), artifacts (potsherds and lithics), and accumulations of edible seafood waste (shellfish middens), all implying sustained occupation, were identified at four sites in upland Yadua, including two hillforts (Koromakawa and Uluinakoro) and two lookout posts (Nacelau and Uluikota). Radiometric ages suggest the two hillforts were occupied during the seventeenth century or perhaps established earlier, making them coeval with hillforts elsewhere in Fiji and other tropical Pacific Island groups. Information about Pacific Islands settlement throughout the last millennium can still be obtained from islands like Yadua through fieldwork and the collection of oral traditions. Oral traditions and human-made structures are likely to disappear within a few decades, owing to the increasing reach of globalization and ongoing physical degradation respectively; research of the kind described in this article is thus a priority.

This study investigated different approaches to optimize flows in misaligned culverts. Structures aligned with the natural stream are always preferred, as misalignments cause a change of direction at the culvert inlet associated with lower performance and sedimentation and erosion problems. This optimal positioning can cause high financial costs and a flow optimization minimizing the associated problems could be a viable alternative. In this study, we used computational fluid dynamics analysis to evaluate the flow in 44 different scenarios with misalignment angles ranging from 0 ∘ &ndash, 90 ∘ . It was found that smooth transitions towards the narrowest point in the stream (culvert) were possible for any degree of misalignment resulting in improved, uniform velocity distributions and less turbulence. An experimental setup was able to confirm the possible flow improvements. The proposed approach of flow redirection can lower construction costs and gives planners and designers more flexibility as tailored reinforcement and redesign of the stream embankment can be used as an alternative to costly creek alignments.

Culverts, as an essential part of drainage networks worldwide, provide an efficient solution for flowing waters to cross man-made barriers including roads. Existing structures can be many years old and changes in rainfall patterns due to global warming might not have been considered in their original design. While correctly designed culverts can effectively drain water during high-intensity rainfall events, poorly designed or outdated structures could cause upstream flooding resulting in costly damage and losses. Hydraulic improvements to prepare existing culverts for greater discharge rates could be a favorable alternative to rebuilding every failing structure. Modern design guidelines calculate the performance for inlet and outlet controlled flows on the basis of established hydraulic theories. After calculating the headwater levels for both flow controls, the inferior one is then chosen, based on the assumption that the culvert will operate in its least efficient state. Flow improvements could be made by enforcing the better performing option. Outlet control can be ensured by raising the tailwater levels as high as the outlet thereby utilizing the entire cross-sectional area of the culvert. It was found that, in some cases, an enforced outlet control enables culverts to perform better than operation under inlet control. However, only smooth and short culverts with high losses at the inlet were identified as benefiting from this approach and many existing structures could be improved by better inlet designs.

This study compared plant growth, nutrient partitioning and total nutrient uptake by tall sedge (Carex appressa) plants in large-scale Constructed Floating Wetlands (CFWs). Two CFWs with a total area of 2088 m2 were installed in a 2.6 ha man-made urban lake to treat stormwater runoff during the construction phase of a 45-ha residential development. After 12 months of operation, parts of the CFWs, with a total area of 147 m2, were removed from the urban lake and relocated into a well-established 0.127-ha stormwater retention pond at another site. Biomass and nutrient concentrations of C. appressa shoots above the floating mat and roots below the mat were analysed at both sites 12, 16 and 25 months after initial planting. Plants at the urban lake maintained an extensive root network but there was no increase in total plant biomass at 16 and 25 months after planting. In contrast, the relocated plants in the stormwater pond showed extensive shoot growth but a significant decline in root biomass. C. appressa at the urban lake removed and sequestered 1.00 ± 1.04 g m−2 N, 0.11 ± 0.07 g m−2 P and 1.03 ± 0.81 g m−2 K while plants at the pond removed 11.20 ± 2.29 g m−2 N, 1.37 ± 0.26 g m−2 P and 16.13 ± 2.88 g m−2 K during 12 and 25 months after planting. This study demonstrated that C. appressa adapted rapidly to changes in nutrient availability. The implications are interesting as nutrient levels can be low in constructed lakes during the initial phase of urban developments but can increase rapidly as the development progresses. The study demonstrated multiple benefits of CFWs for stormwater treatment during the early construction stages of an urban development and the potential benefits of relocating and establishing CFWs in existing stormwater retention ponds and lakes.

Tropical regions of the world experience high rates of land-use change and this has a major influence on terrestrial carbon (C) pools and the global C cycle. We assessed land-use change from agriculture to reforested plantings (with endemic species), up to 33 years of age, using 10 paired sites in the wet tropics, Australia. We determined the impacts on 0–50 cm below-ground C (soil organic C (SOC), charcoal C, humic organic C, particulate organic C, resistant organic C), C stored in roots (fine and coarse), C stored in living above-ground biomass and debris C pools. Reforested areas accumulated ecosystem C at a rate of 7.4 Mg ha−1 yr−1. Reforestation plantings contained, on average, 2.3 times more ecosystem C than agricultural areas (102 Mg ha−1 and 233 Mg ha−1, respectively). Most of the C accumulation was in living above-ground and below-ground biomass (60 and 30%, respectively) with a smaller amount in debris pools (16%). Apart from C in roots, soil C accumulation was not obvious across sites ranging from 8 to 33 years since reforestation, relative to the agricultural baseline. Differences in SOC (and associated SOC pools) to a depth of 50 cm, did exist between reforested areas and adjacent agriculture at some sites, however there was not a consistent trend in SOC associated with reforestation. Local site-based factors (e.g. soil texture and mineralogy, land-use history and microbial activity) appear to have a strong influence on the direction of the change in SOC. While reforestation in the tropics has great potential to accumulate C in biomass in living vegetation, and debris pools, it is likely to take approximately 50 years before C stocks of reforested areas resemble natural ecosystems. Accumulation of SOC through reforestation is difficult to achieve, highlighting the need to conserve carbon pools in remnant forests in the tropics.

Concern for the maintenance of water quality of the lakes on K'gari-Fraser Island has attracted research attention but the impact of beach camping on beach freshwater has been poorly considered. The assumption has been that the natural assimilative capacity of the foredune ecosystem is sufficient to dissipate any negative environmental impact. An exploratory study of nutrients, faecal coliforms and faecal sterols in the watertable and beach flows associated with camping and non-camping zones reveals concerning differences between sample sites. The study suggests nutrient levels in the watertable are enriched in camping zones and that, in some areas, faecal coliforms persist in beach flows. The link to a human cause is supported by the presence of strong faecal sterol signals in soil samples from the watertable interface. The risk implications for human health are significant although the biological impact implications remain unexplored.

This paper presents the findings of a study into how different inlet designs for stormwater culverts increase the discharge rate. The objective of the study was to develop improved inlet designs that could be retro-fitted to existing stormwater culvert structures in order to increase discharge capacity and allow for changing rainfall patterns and severe weather events that are expected as a consequence of climate change. Three different chamfer angles and a rounded corner were simulated with the software ANSYS Fluent, each of the shapes tested in five different sizes. Rounded and 45 ∘ chamfers at the inlet edge performed best, significantly increasing the flow rate, though the size of the configurations was a critical factor. Inlet angles of 30 ∘ and 60 ∘ caused greater turbulence in the simulations than did 45 ∘ and the rounded corner. The best performing shape of the inlet, the rounded corner, was tested in an experimental flume. The flume flow experiment showed that the optimal inlet configuration, a rounded inlet (radius = 1/5 culvert width) improved the flow rate by up to 20% under submerged inlet control conditions.

The diet of the European red fox (Vulpes vulpes) was investigated through analysis of 1185 scats collected between 2010 and 2014 from coastal south-east Queensland, Australia. By both frequency of occurrence and volume, its diet was dominated by terrestrial arthropods, marine arthropods, vegetation and birds, although the remains of the short-tailed shearwater (Ardenna tenuirostris) consumed as carrion dominated the latter. Terrestrial arthropods, primarily insects of the order Coleoptera, were eaten all year (61% frequency of occurrence, FO) but varied seasonally (35–67%FO), mostly due to the consumption of large numbers of Christmas beetles (Anoplognathus spp.) in the summer months. Marine arthropods consisted almost entirely of ghost crabs (Ocypode spp.) and seasonal variation in consumption was evident (33–72%FO) and likely correlated with ghost crab abundance. Fruit and berries were an important food item for foxes all year but also varied seasonally (30–65%FO). The opportunistic diet of this fox population is discussed in the context of dietary differences, but common opportunism, reported in other Australian and overseas studies.

In response to the absence of monitoring data, the Air Pollution Model (TAPM), a 3D prognostic model that predicts both meteorology and air pollution concentrations, was used to investigate the transport of ammonia across part of the Sunshine Coast region (South East Queensland, Australia), following its emission to the atmosphere from 41 poultry farms (egg and broiler) in the district, which cumulatively house approximately 9.8 million fowl. The study estimated the total amount of ammonia that is deposited directly into the Pumicestone Passage waterbody (63 km 2 ) and onto the surrounding catchment (1184 km 2 ), through both wet and dry deposition processes over a twelve-month period. The results indicate that wet deposition is the dominant deposition process into the waterbody (89%) and catchment area (94%). Most of the ammonia deposition is predicted to occur within a relatively short distance from the farms, due to higher concentrations at these locations. In the base case simulation, the estimated 1823 tonnes of annual ammonia emissions were predicted to result in the direct deposition of approximately 2.3 tonnes of ammonia into the Pumicestone Passage waterbody and approximately 53.5 tonnes onto the Pumicestone Passage catchment land surface, where there was potential for its subsequent run-off into the waterbody. This annual loading into the waterbody is not insignificant and is likely to contribute to the formation of algal blooms. The fate of the remaining 91% of the ammonia estimated to be emitted from the farms was not accounted for in the deposition totals. This ammonia most likely remains suspended in the atmosphere and is transported outside of the simulation study area.

[Extract] Given the significant natural resource problems that we face, the results of Australia's decade-long experiment in more devolved approaches to natural resource management (NRM) is of deep national, if not international, significance. Despite this significance, until the release of Contested country, the literature on this subject has been sparse and fragmented. There also has been a stronger focus on evaluative-style literature (often poorly contextualised) and few contributions to theoretical debate about integrated governance. Happily, Contested country is the first edited compendium to successfully bring together Australian knowledge and research capability regarding this topic. Its timing is perfect, given the emerging transformation in our national approach to NRM program delivery, commencing with the 2007 shift in national political leadership and the consequent return to a more centralised, purchaser-provider approach to NRM.

South East Queensland is one of the fastest growing regions in Australia with a correspondingly rapid increase in sewage production. In response, local councils are investing in more effective and sustainable options for the treatment and reuse of domestic and industrial effluents. A novel, evaporative solar dryer system has been installed on the Sunshine Coast to convert sewage sludge into a drier, usable form of biosolids through solar radiation exposure resulting in decreased moisture concentration and pathogen reduction. Solar-dried biosolids were analyzed for selected pathogenic microbial, metal and organic contaminants at the end of different drying cycles in a collaborative study conducted with the Regional Council. Although fecal coliforms were found to be present, enteroviruses, parasites, E. coli, and Salmonella sp. were not detected in the final product. However, elevated levels of zinc and copper were still present which restricted public use of the biosolids. Dilution of the dried biosolids with green waste as well as composting of the biosolids is likely to lead to the production of an environmentally safe, Class A end-product.

Rapidly transforming landscapes are places in which biodiversity loss is likely. Where urbanisation is rapid, conservation planners are often unable to afford the necessary time to adequately gather data and assess threats to biodiversity. Better methodologies are required to inform decision making about development assessments and conservation planning. This paper argues for adopting GIS (geographic information systems) that incorporate available scientific and community-based data and scenarios modelling within the policy framework, to derive geographic surrogates and impact surrogates for conservation planning. This methodology is applied to a pilot study of raptors on the Sunshine Coast, Australia, and evaluates its efficacy. Preliminary results suggest that, while there are some limitations, this methodological approach offers useful insights to conservation planning. Other key findings imply that current planning frameworks are insufficient to protect raptors in this area. Non-remnant veget...

Four different field swales were tested in this study, using 24 standardised synthetic runoff simulation experiments to evaluate their performance in removing Total Suspended Solids (TSS), Total Nitrogen (TN) and Total Phosphorous (TP) from stormwater runoff. Hydraulic reduction capability of the swales was also assessed. The study demonstrated that a swale’s TSS removal performance is highly dependent on the inlet TSS concentrations. Results showed that between 50% and 80% of the TSS was generally removed within the first 10 m of the swale length. The study found no reduction in TN concentrations due to treatment by the swales. However, it did demonstrate a reduction in measured TP levels of between 20% and 23% between the inlet and the outlet. The study results demonstrated that swales can be successfully used to attenuate peak stormwater flow rates, reduce runoff volumes and to improve the quality of stormwater runoff, particularly in runoff with high concentrations of TSS and TP. The results from this study will assist designers to estimate the appropriate length of swale required to achieve specific TSS and TP pollution reductions in urban stormwater runoff and to reduce downstream runoff volumes.

The wet deposition of iron and peroxides was monitored during an intense rain squall in the equatorial Pacific Ocean. Iron and hydrogen peroxide were determined at sea using adsorptive cathodic stripping voltammetry (ACSV) and an enzyme-catalyzed flourometric technique, respectively. The equatorial rainwater was enriched in ACSV reactive iron (average 2.7 nmol Fe kg−1) and hydrogen peroxide (average 8.5 μmol kg−1) relative to the concentrations found in surface seawater (0.05–0.07 nmol Fe kg−1; 40–70 nmol peroxides kg−1). Wet depositional fluxes during the squall varied from 70 to 105 nmol Fe m−2 h−1 and from 56 to 880 μmol peroxide m−2 h−1. The input of rainwater into the surface layer was documented by using hydrogen peroxide and iron signals as well as the depression in surface salinity as tracers. The squall created a patch of lower-salinity surface seawater that was relatively enriched in ACSV reactive iron (0.2–0.3 nmol Fe kg−1) and peroxides (200–300 nmol kg−1). The observed concentrations of iron and peroxides in rainwater, their wet-depositional fluxes, and their initial sea surface enrichments, were quantitatively consistent with independent predictions based on applicable iron aerosol and gas-phase peroxide scavenging models for the region.

Sand samples and Landsat imagery were used to characterize the spatial distribution of sand mineralogy, and to evaluate potential sources and transport pathways of sediment in the Wahiba Sand Sea in the Sultanate of Oman. Landsat TM data were useful in the geomorphic interpretation of a desert, aeolian environment to distinguish the mineralogies found in the Wahiba area, and in extending the identification of sand mineralogy beyond the point-specific grid produced from field sampling. The Wahiba Sand Sea has been previously divided into upper (north and higher in elevation) and lower (south and lower in elevation) portions, based on dune morphology. Large-scale spatial distributions of mineral composition follow a similar pattern to that of the geomorphic regions within the dune field. Field and Landsat TM data suggests the upper Wahiba is comprised of well-mixed carbonate and quartz sand with some areas of significant mafic content. Surface sand in the eastern and western margins of the upper Wahiba originate from the lower Wahiba and from local wadis. Sand in the lower Wahiba was likely derived from southern sabkhas and the coastal area and is quartz-rich with isolated locations of carbonate-rich sand. We suggest that these carbonate-rich patches in the lower Wahiba were derived from reworked aeolianites (lithofied sand dunes) which underlie most of the sand sea, and not directly from the coast, as previously reported.

This paper provides an overview of dust transport pathways and concentrations over the Arabian Sea during 1995. Results indicate that the transport and input of dust to the region is complex, being affected by both temporally and spatially important processes. Highest values of dust were found off the Omani coast and in the entrance to the Gulf of Oman. Dust levels were generally lower in summer than the other seasons, although still relatively high compared to other oceanic regions. The Findlater jet, rather than acting as a source of dust from Africa, appears to block the direct transport of dust to the open Arabian Sea from desert dust source regions in the Middle East and Iran/Pakistan. Dust transport aloft, above the jet, rather than at the surface, may be more important during summer. In an opposite pattern to dust, sea salt levels were exceedingly high during the summer monsoon, presumably due to the sustained strong surface winds. The high sea salt aerosols during the summer months may be impacting on the strong aerosol reflectance and absorbance signals over the Arabian Sea that are detected by satellite each year.

Climatological maps of monthly mean aerosol radiance levels derived from the coastal zone color scanner (CZCS) were constructed for the world's ocean basins. This is the first study to use the 7.5.-year CZCS data set to examine the distribution and seasonality of aerosols over the open ocean on a global scale. Examination of our satellite images found the most prominent large-scale patch of elevated aerosol radiances in each month off the coast of northwest Africa. The well-known, large-scale plumes of elevated aerosol levels in the Arabian Sea, the northwest Pacific, and off the east coast of North America were also successfully captured. Radiance data were extracted from 13 major open-ocean zones, ranging from the subpolar to equatorial regions. Results from these extractions revealed the aerosol load in both subpolar and subtropical zones to be higher in the Northern Hemisphere than in the Southern Hemisphere. Aerosol radiances in the subtropics of both hemispheres were about 2 times higher in summer than in winter. In subpolar regions, aerosol radiances in late spring/early summer were almost 3 times that observed in winter. In general, the aerosol signal was higher during the warmer months and lower during the cooler months, irrespective of location. A comparison between our mean monthly aerosol radiance maps with mean monthly chlorophyll maps (also from CZCS) showed similar seasonality between aerosol and chlorophyll levels in the subpolar zones of both hemispheres, i.e., high levels in summer, low levels in winter. In the subtropics of both hemispheres, however, chlorophyll levels were higher in winter months which coincided with a depressed aerosol signal. Our results indicate that the near-IR channel on ocean color sensors can be used to successfully capture well-known, large-scale aerosol plumes on a global scale and that future ocean color sensors may provide a platform for long-term synoptic studies of combined aerosol-phytoplankton productivity interactions.

The temporal and spatial patterns of dust concentrations and geochemistry of aerosols collected over the Arabian Sea, along with atmospheric transport models, were used to identify source areas from the surrounding desert environments. Seasonally, the highest dust levels occurred during the winter and spring, with probable source areas in India/Pakistan/Iran and the Arabian Peninsula. Spatially, the highest dust levels were found off the Omani coast and over the Gulf of Oman, where high dust levels persisted throughout the year, suggesting that the Arabian Peninsula, and perhaps Oman specifically, are the most prominent contributors to the annual dust load in the region.

We develop a tool to assist in identifying a link between naturally occurring aeolian dust deposition and phytoplankton response in the ocean. Rather than examining a single, or small number of dust deposition events, we take a climatological approach to estimate the likelihood of observing a definitive link between dust deposition and a phytoplankton bloom for the oceans proximal to the Australian continent. We use a dust storm index (DSI) to determine dust entrainment in the Lake Eyre Basin (LEB) and an ensemble of modelled atmospheric trajectories of dust transport from the basin, the major dust source in Australia. Deposition into the ocean is computed as a function of distance from the LEB source and the local over-ocean precipitation. The upper ocean's receptivity to nutrients, including dust-borne iron, is defined in terms of time-dependent, monthly climatological fields for light, mixed layer depth and chlorophyll concentration relative to the climatological monthly maximum. The resultant likelihood of a dust-phytoplankton link being observed is then mapped as a function of space and time. Our results suggest that the Southern Ocean (north of 45°S), the North West Shelf, and Great Barrier Reef are ocean regions where a rapid biological response to dust inputs is most likely to be observed. Conversely, due to asynchrony between deposition and ocean receptivity, direct causal links appear unlikely to be observed in the Tasman Sea and Southern Ocean south of 45°S. © 2013 Elsevier B.V.

Urban lakes are often monitored and managed with limited consideration of adjacent communities. Generally, when communities are considered in relation to urban lakes, they are viewed simply as sources of pollutants. Given the inevitable interactions between an urban lake and the surrounding inhabitants, the community must be considered explicitly when assessing the ecosystem health of urban lakes, as the two entities intrinsically comprise interrelated parts of a single ecosystem. In this study, the reciprocal links between a residential community and a series of urban lakes in South East Queensland have been examined to facilitate a dynamically linked, fully integrated ecosystem health assessment of constructed urban lakes. Residents' attitudes towards, and values derived from, a series of urban lakes were surveyed, as well as residents' behaviours which may impact upon urban lake health. The results indicate that residents derive both tangible and intangible benefits from the urban lakes, but feel little responsibility for lake health or custodianship over the lakes. Greater recognition within urban lake management frameworks of the links between urban lake systems and their surrounding communities may help to foster and enhance both community well-being, a greater sense of custodianship for such systems and improved management. Refereed/Peer-reviewed

The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km2 in the open equatorial Pacific Ocean with iron. This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production. Similar increases were found in a chlorophyll-rich plume down-stream of the Galapagos Islands, which was naturally enriched in iron. These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean.

On a transect study in the eastern equatorial Pacific, from the high-nutrient, low-chlorophyll tropical waters to the oligotrophic subtropical waters, we determined the variability in the maximum change in the quantum yield of chlorophyll fluorescence (A&,) by means of a fast repetition rate fluorometer. A& is a quantitative measure of photochemical energy conversion efficiency in photosystem 2, the variability of which is determined by the functional organization of the photosynthetic apparatus. The results revealed that A&,, was relatively low throughout the nutrient-rich equatorial waters, providing unequivocal evidence for physiological limitation of photochemical energy conversion efficiency in the natural phytoplankton populations. Shipboard enrichment studies showed that A&, increased following addition of nanomolar concentrations of inorganic iron as well as aerosol dust added at similar iron concentrations. This response reflects an iron-induced repair of photosystem 2 function in the enclosed bottle community. Low A&, at the top of the Equatorial Undercurrent indicated that the amount of iron upwelled to the surface was insufficient .t,o repair photosystem 2 function. Our results strongly suggest that iron availability limits photochemrcal energy conversion efficiency and is the principal mechanism controlling rates of photosynthesis and growth in the nutrient-rich equatorial Pacific.

Marine aerosol particles from the Equatorial Pacific were studied using transmission electron microscopy. Sea-salt aggregates consist largely of NaCl and Na-Ca sulfate crystals. Variations in the composition of sea-salt aggregates occur, and these may reflect the effects of relative humidity. There are several species of submicron, S-bearing particles, presumably including ammonium sulfate and strong acids. Diatom fragments are common, and sparse kaolinite and rutile crystals are the mineral component of this marine aerosol. The samples we studied appeared to be free of obvious anthropogenic effects.

In this study, faecal sterols were used to identify human faecal pollution in a non-sewered catchment in Southeast Queensland, Australia. In all, 36 water samples were collected from six sites on six occasions and the concentration of sterols were determined using gas chromatography and mass spectrometry. The stanols concentration in water samples generally increased with increased catchment runoff. After moderate rainfall, high coprostanols levels found in water samples indicated human faecal pollution via defective septic systems. In contrast, it appears that during dry weather human faecal pollution is not occurring in the study catchment. Sterol profiles also pointed to a cattle farm polluting during modest catchment runoff. The method used in this study was able to identify the sources of faecal pollution to the catchment due to rainfall.

The atmospheric transport of continental weathering products is responsible for much of the mineral material and Fe entering the open ocean and is probably the dominant source of nutrient Fe in the photic zone. In regions where other nutrients are present in high concentrations, the flux of Fe from the atmosphere may be a limiting factor in primary productivity. Due to the larger source regions for dust north of the equator, ∼8 times more atmospheric Fe is deposited in the northern hemisphere than in the southern hemisphere. The mineral aerosol and Fe transport and deposition are highly variable due to the episodic nature of dust generation and its transport and deposition processes. Between 10 and 50% of the total atmospheric Fe entering the world ocean appears to dissolve (i.e. it will pass through a 0.4-µm pore-size filter) rapidly when the mineral matter enters the ocean. Much of the atmospheric Fe is present as Fe(II), apparently produced as a result of photochemical reduction reactions taking place during atmospheric transport. This readily soluble Fe(II) should be available immediately for use as a nutrient by phytoplankton. Atmospheric transport from the continents is estimated to supply ∼3 times as much dissolved Fe to the oceans as that delivered via rivers.

As part of the Asian Dust Inputs to the Ocean System (ADIOS) project, atmospheric dust fluxes and primary productivity were monitored during the dusty season (spring) of 1986 at 26°N, 155°W, in the North Pacific Ocean. The arrival of major pulses of dust from Asia was followed by major increases in primary production. Extensive chemical analyses of the atmospheric particles showed that they were iron-rich (10-15%) and, further, that if only a small proportion (e.g. 10%) of this iron dissolved in the euphotic zone, it would be sufficient to support the increases in carbon production at this location. The systematic increases in production noted with increasing depth and time may result from a continual release of iron from the settling particles in the euphotic zone. At all depths, systematic decreases in production followed the initial surge in production, indicating that the phytoplankton may have evolved from being iron-limited to being nitrogen-limited. Comparison of particle concentrations calculated by a particle settling model with primary productivity profiles indicated that mineral particles with settling velocities equivalent to those of 14 to 18-μm-diameter spherical quartz particles were the most likely source for the iron stimulating the increases in primary production.

Measurements in a Lewis cell of the kinetics of extraction of copper(II) by 5-nonyl-2-hydroxybenzaldoximes from acidic (hydrogen sulphate buffer) aqueous solution, in the pH range 3.4-2.0, into n-hexane are reported. The effects of changes in the dielectric constant and the viscosity of the organic phase on the rate of extraction have been measured. The effect of the presence of hydroxylic modifiers on kinetics of extraction was also examined. Measurements of the lowering of interfacial tension in these systems were also carried out. The results of all of our experiments agree in showing that, at low initial bulk concentrations of the extractant (less than 1 mol/m3), the rate of extraction is controlled by the interfacial concentration of the extractant and by the rate of diffusion of extractant from the bulk to the interface.

ATMOSPHERIC INPUTS of iron and nitrogen have been hypothesized to play an important role in the chemical and biological dynamics of openocean ecosystems (Menzel and Spaeth, 1962; Duce, 1986). This hypothesis has stimulated considerable discussion and controversy (see Martin, 1991, this issue; Miller et al., 1991, this issue; Morel et al., 1991, this issue). Much of this discussion has focused on the relative importance of atmospheric nutrient input rates over large time and space scales, the physiology and chemistry of iron nutrition, the elemental composition of phytoplankton (e.g., Fe/C), and the interpretation of assays for iron limitation ofphytoplankton growth at a particular time and place. An interdisciplinary analysis has led to the realization that biological responses of oceanic ecosystems are likely to be dependent not only on biological requirements and the large-scale variability in annual-average atmospheric inputs but also on the temporal and spatial variability of these inputs, on the chemical and biological processes controlling the fate of those inputs, and on the biological, chemical, and physical interactions controlling the dynamics of open-ocean ecosystems receiving those inputs. The results of this interdisciplinary analysis are summarized below.

[1] Dust is an important vector for iron supply to the ocean, which subsequently impacts ocean productivity, atmospheric CO2 concentrations, and hence global climate. Here, we synthesize the processes influencing the biogeochemistry of Australian dust and compare them with those from other Southern Hemisphere dust sources. Our observations range from soil and dust physical properties to abrasion and cloud chamber chemistry experiments to dust storms and their dispersion and deposition. We then present satellite observations of the impact of episodic dust deposition events on the productivity of low-iron oceanic waters north (i.e., low-nitrate, low-chlorophyll (LNLC)) and south (i.e., high-nitrate, low-chlorophyll (HNLC)) of Australia. Dust deposition from the largest dust storm in over 40 years did not result in iron-mediated algal blooms in either oceanic region. A comparison of Australia with other Southern Hemisphere source regions reveals that the relatively well sampled Australian system is a poor generic model. Furthermore, there are marked distinctions between Southern and Northern Hemisphere iron/dust biogeochemistry that must be recognized by modelers and included in future simulations. Better information is required on the relative role of the atmosphere and ocean on influencing iron biogeochemistry and how their relative influences might change in the future due to climate change.

[1] Two hypotheses that postulate interactions between ocean biota and aerosols in the atmosphere have generated substantial research into marine systems. The stimulation of phytoplankton photosynthesis by the provision of iron, a micronutrient contained in deposited aeolian dust (the Iron Hypothesis), and the contribution of dimethylsulphide (DMS) produced by marine ecosystems to the atmospheric burden of aerosols (the CLAW Hypothesis) have been the focus of much research. Satellite sensors, such as the Seaviewing Wide Field-of-view Sensor (SeaWiFS) now provide moderate-resolution time series of measurements of the optical properties of the oceans and atmosphere over most of the Earth’s surface. These data provide an unprecedented opportunity to investigate the ubiquity of biotic linkages between the ocean and atmosphere at the global scale. We analyzed 5 years of SeaWiFS 8-day fields of two variables, chlorophyll concentration and aerosol optical depth, for the global oceans. This first global, multiyear approach does not yet allow unequivocal conclusions, as satellite measurements of chlorophyll can be influenced by aerosol properties of the atmosphere and several variables we do not yet examine are likely to play a role. We find correlation between optical properties of the ocean and atmosphere over much of the globe, in particular the midlatitudes. While some regional analyses indicate that SeaWiFS chlorophyll retrievals are biased by dust in the atmosphere, our results do not support the existence of widespread bias in the SeaWiFS products, but are consistent with global-scale couplings posited by the Iron and CLAW hypotheses.

[1] Methyl bromide (CH3Br) was highly supersaturated for over 2 years in the surface coastal seawater off Tasmania. Persistent supersaturations were observed near to shore throughout the year with no evidence of a seasonal cycle. At the same time, a site farther offshore (still under coastal influence) was also predominantly supersaturated but to a lesser extent. Notably, the annual pattern varied over the consecutive years covered in this systematic study. The observed supersaturations are in broad agreement with that which would be predicted by the relationships with the sea surface temperature (SST) derived by Groszko and Moore [1998] and King et al. [2000] for SSTs in the range of 12° to 20°C, although not the seasonal variation predicted by King et al. [2002]. There is much variability, as expected, which is not explained by the SST relationships. The presence of the prymnesiophyte Phaeocystis is found to be related to the seawater concentrations of CH3Br in this work. Our results tentatively indicate that the release of CH3Br into the seawater may be a response to nitrate limiting conditions.

During the Southern Hemispheric spring of 2000 (during the months of November and early December), rain, bulk and size-separated aerosol samples were collected at the Cape Grim Baseline Air Pollution Station located on the island of Tasmania, Australia and analyzed for total organic nitrogen (N), urea, and dissolved free amino acids. Rain and bulk aerosol samples contained organic N at concentrations representing, on average, between 19 and 25% of total N. Urea was not detected in the six rain samples analyzed. However, urea represented ∼24% of the organic N contained in nonbaseline aerosol samples, and ∼2% of the organic N contained within baseline samples. Trajectory analysis combined with meteorological data indicated that high concentrations of urea within aerosols were mainly due to Tasmanian sources, likely animal emissions, although the application of urea fertilizers cannot be dismissed as a source. In nonbaseline samples the highest concentrations of urea were associated with the coarse mode aerosol (greater than 1 μm), although urea was also found in the fine mode aerosol (less than 1 μm), potentially indicating gas-to-particle conversion of urea. Aerosol samples collected in marine air masses contained urea within an intermediate fraction centered at ∼1 μm suggesting the sea surface microlayer as a source. Dissolved free amino acids contributed ∼53% of the organic N in rain, but were not a significant proportion of the total organic N fraction in either nonbaseline or baseline aerosol samples. Due to their presence in rain, amino acids likely exist in aerosols as unhydrolyzed proteins. In cascade impactor samples highly influenced by marine sources, profiles for amino N were inversely related to urea N, possibly indicating live species and the sea surface microlayer as a source for organic N.;

Measurement of the kinetics of extraction of copper(II) by 19 different 5-alkyl-2-hydroxybenzaldoximes (alkyl is C7H15 and C9H19) from acidic (hydrogen sulfate buffer) aqueous solution in the range pH 3.4-2.0, into 20% v/v toluene in n-hexane is reported. The lowering of the interfacial tension has been measured in some cases. The solubility of the extractants in water has been measured spectrophotometrically. A modified Taylor-Aris dispersion technique has been used to measure the diffusion coefficients in n-hexane and Orfom SX7 of some of the extractants and of the copper(II) complexes which they form. At low initial bulk concentrations (10 mol m-3) of the extractants, the rate of extraction is controlled by the rate of diffusion of the extractant from the bulk to the organic-aqueous interface. The diffusion coefficient is related to the steric bulk of the alkyl substituent. At higher initial bulk concentrations (200 mol m-3) of the extractants, when the interface is saturated, the rate of extraction is inversely related to the apparent steric bulk of the alkyl substituent. Copyright 1999 Academic Press.

It is becoming clear that the global climate system is controlled by numerous links between the biosphere and the atmosphere. The objective of IGAC’s Marine Aerosol and Gas Exchange: Atmospheric Chemistry and Climate (MAGE) Activity is to quantify those links through interdisciplinary multinational research on air/sea exchange and its biological controls and impacts. We seek to bring together scientists from a variety of disciplines to study the interfaces between them. Wherever possible, we encourage collaborative work between marine scientists who look up at the interface from the water column and atmospheric chemists, whose work in the atmosphere has frequently treated the ocean’s surface as a featureless source or sink.

Individual particle analysis involves the study of tens of thousands of particles using automated scanning electron microscopy and elemental analysis by energy-dispersive, x-ray emission spectroscopy (EDS). EDS produces large data sets that must be analyzed using multi-variate statistical techniques. A complete study uses cluster analysis, discriminant analysis, and factor or principal components analysis (PCA). The three techniques are used in the study of particles sampled during the FeLine cruise to the mid-Pacific ocean in the summer of 1990. The mid-Pacific aerosol provides information on long range particle transport, iron deposition, sea salt ageing, and halogen chemistry.Aerosol particle data sets suffer from a number of difficulties for pattern recognition using cluster analysis. There is a great disparity in the number of observations per cluster and the range of the variables in each cluster. The variables are not normally distributed, they are subject to considerable experimental error, and many values are zero, because of finite detection limits. Many of the clusters show considerable overlap, because of natural variability, agglomeration, and chemical reactivity.

Several recent studies have shown that large quantities of mineral dust from eastern Asia are transported through the atmosphere to the North Pacific each spring1–5. The paucity of information on mineral fluxes during individual dust events prompted a coordinated effort, Asian Dust Input to the Oceanic System (ADIOS), which simultaneously measured mineral fluxes in the atmosphere and upper water column during such an event. In March 1986 a major dust outbreak in China moved over the North Pacific Ocean and was detected downstream using changes in particle number, size and composition. Most striking was the presence of 'giant' (>75-μm) silica minerals found in atmospheric as well as water-column samples at the ADIOS sampling site (26° N, 155° W). Their appearance more than 10,000 km from their source cannot be explained using currently acknowledged atmospheric transport mechanisms. Furthermore, the large wind-blown minerals that dominated our samples are extremely rare in the long-term sedimentary record in the North Pacific.