Southern Sydney Research Articles

Depositional environment, organic matter sources, and variable 17α(H)-diahopane distribution in Early Permian samples, southern Sydney Basin, Australia

Early Permian strata exposed in the southern part of the Sydney Basin, NSW, Australia, include the Pebbley Beach Formation, the Snapper Point Formation and the Wandrawandian Siltstone. These formations were deposited during the Late Paleozoic Ice Age, when Australia was close to the South Pole. The Pebbley Beach and Snapper Point formations were deposited in shallow marine to coastal environments, while the Wandrawandian Siltstone was deposited in deeper water following a marine transgression. However, opinions differ on the precise environmental and climatic conditions that prevailed during their deposition. Sixteen outcrop samples from these formations were collected and analysed to determine their depositional conditions and the source(s) of their organic matter.The biomarker and aromatic hydrocarbon distributions show that the rocks are in the early to mid-oil window. Some aromatic parameters show that the stratigraphically younger Wandrawandian Siltstone is more thermally mature than the older Pebbley Beach Formation, which is interpreted to be due to the geographic position of these outcrops in the Sydney Basin. The samples have low to intermediate pristane/phytane ratios (from 1.4 to 3.4), showing variation from oxic to suboxic depositional conditions. Most of the mudstones and siltstones sampled were deposited in a marine environment, with some fluvial-deltaic or estuarine influence, and contain mixed type II and type III organic matter. The Pebbley Beach formation is characterised by terpane distributions dominated by the C24 tetracyclic terpane, and to a lesser extent the C19 tricyclic terpane. The Snapper Point Formation has a mix of C19 and C23 tricyclic terpanes and C24 tetracyclic terpane, while the Wandrawandian Siltstone is dominated by C19, C21, and C23 tricyclic terpanes. The sterane distribution follows a C29 > C28 > C27 pattern in the majority of the samples, including in the marine deposited Wandrawandian Siltstone. The three formations have very variable relative amounts of diahopanes and other rearranged hopanes, with the highest C30*/C30 αβ hopane ratio (6.9) in the Wandrawandian Siltstone. This formation also has high amounts of diasteranes compared to the other two formations, but the relative amounts of diasteranes are not as high as for the diahopanes. Classically, this suggests a clay-rich sediment in an oxic or suboxic, acid-catalysed depositional environment, with enhanced diagenetic alteration of the biomarkers. The Wandrawandian Siltstone was deposited in suboxic conditions, not unusual to many rocks that contain much less rearranged hopanes. Unusual characteristics of the Wandrawandian Siltstone include significant slumping and soft sediment deformation, and deposition under periglacial-glacial conditions. The occurrence of the slumps on the continental slope led to significant sediment overturn, and this may have resulted in enhanced diagenetic and catalytic rearrangement reactions, leading to the elevated levels of diahopanes and other rearranged hopanes. The disequilibrium between the relative abundances of diahopanes and diasteranes suggests different formation mechanisms for these biomarkers.

A New High-Paleolatitude Late Permian Permineralized Peat Flora from the Sydney Basin, Australia

Premise of research. Permineralized peats are prized for hosting three-dimensionally preserved plant remains that provide insights into fossil plant anatomy and the composition of coal-forming ecosystems. A new record of siliceous permineralized peat is documented from a Lopingian-aged (upper Permian) strata from the southern Sydney Basin. It represents the fifth Permian permineralized peat identified from eastern Australia.Methodology. The single permineralized peat block was cut into smaller blocks, and both cellulose acetate peels and standard thin sections were prepared for study using transmitted light microscopy. Quantitative analysis of the peat was carried out using point counts perpendicular to bedding. One block examined using synchrotron X-ray computed tomography (CT) revealed the three-dimensional anatomy of abundant fossil seeds.Pivotal results. The peat contains a plant assemblage dominated by glossopterid leaves, seeds, and axes; although degraded, probable pteridophyte remains represent a significant subsidiary component of the assemblage. A new leaf form (Glossopteris thirroulensis McLoughlin et Mays sp. nov.) and a new type of seed (Illawarraspermum ovatum McLoughlin et Mays gen. et sp. nov.) are described. Leaf-, wood/seed-, and fine detritus-rich organic microfacies with gradational boundaries are evident within the peat.Conclusions. Regular growth rings in the small permineralized axes, together with the occurrence of autumnal mats of glossopterid leaves, signify a strongly seasonal climate. The presence of abundant charcoal in the peat indicates that fire was a significant influence on the high-paleolatitude mire ecosystem. Differentiation of organic microfacies within the peat profile indicates subtle variation in the contribution of plant components to the peat through time. The absence of mineral grains in thin section and CT, together with the presence of authigenic sulfides, indicates accumulation of organic matter in a stagnant mire away from the influence of clastic input.

Structural Evolution of the Thirlmere and Mount Tomah Monoclines: Southern Sydney Basin NSW

The Southern Sydney Basin is a geological region of sub-horizontal conforming strata, including significant coal measures that have been mined for over 100 years. This apparently simple ‘layer-cake’ geology has overlooked many complexities associated with intrusions and a variety of geological structures. This over-simplification of geology has contributed to uncertainty in groundwater model outcomes, and impacts to surface hydrology and groundwater systems that have occurred at some sites. The aim of this study was to identify and characterize geological complexities within the Southern Sydney Basin with a particular focus on near surface groundwater and wetlands which could be sensitive to these direct or indirect disturbances.An initial desk top review of existing drill-hole data, outcrop maps and typical spatial data was undertaken to highlight areas of possible structural inconsistency and areas with a high probability of faults or other structures such as monoclines. This data was then used in combination with field based geological mapping and high quality digital terrain modelling to assist the current development of a series of kinematic (geologically restored) cross-sections.This has enabled the preliminary modelling of fault propagation folds associated with the inversion of growth faults, which will be important in the development of a framework to better identify and define the geometry of aquitards, associated with the Thirlmere Lakes and groundwater surface expression dependent ecosystems (swamps) over the Southern Sydney Basin. This greater understanding of the features around the Thirlmere Lakes area will lead to the development of a structural evolution model that further explains the incision of Blue Gum Creek and the development of Thirlmere Lakes within an entrenched meander.

Organic geochemistry and petroleum potential of Permian outcrop and core samples from the southern Sydney Basin

Permian sediments occur throughout the southern Sydney Basin, exposed on the coastline south of Wollongong, and penetrated by various boreholes. This study uses outcrop samples and samples from three boreholes held by NSW Resources and Energy at the core library at Londonderry (Department of Mines Callala DDH1 [Callala-1] from near Callala Bay, Elecom Clyde River DDH07 [ECR-7] from near Nowra, and Elecom Clyde River DDH01 [ECR-1] from near Wingello). Formations analysed include the Berry Siltstone, Nowra Sandstone, Wandrawandian Siltstone, the Snapper Point Formation, the Pebbley Beach Formation and the Yarrunga Coal Measures. The objectives are to determine the depositional environment, organic matter inputs, thermal maturity and petroleum generation potential of these formations, which were deposited when Australia was close to the South Pole. The rocks at outcrop and in ECR-1 are in the early oil window, while rocks from near Jervis Bay (Callala-1, ECR-7) are in the gas window. Total organic carbon content is heterogeneous and varies from 0.2–6.7%. The rocks were deposited in oxic to suboxic depositional environments. The Wandrawandian Siltstone contains biomarkers dominated by very high amounts of diahopanes and diasteranes, whereas these biomarkers are of lower relative abundance in the other formations. This is suggestive of a clay-rich sediment in an oxic, acid-catalysed depositional environment, with enhanced diagenetic alteration of the biomarkers, or alternatively an unusual organic input. The Pebbley Beach and Snapper Point formations are characterised by biomarker distributions dominated by terrigenously sourced terpanes (e.g. C24 tetracyclic terpane and C19 tricyclic terpane), corroborating their deltaic and shallow marine depositional environments, respectively. In contrast, the Wandrawandian Siltstone contains dominantly C21, C23, and C24 tricyclic terpanes. The Pebbley Beach Formation contains high amounts of C29 relative to C28 and C27 steranes, also consistent with a dominant terrigenous input.

Coastal homemaking: Navigating housing ideals, home realities, and more-than-human processes

As urban populations expand, high natural amenity locales—forests, bushland, and coasts—are being transformed into highly desired, lucrative locations for new housing. This paper examines what it means to live in such an environment, tallying between the realised dream of that lifestyle and the everyday challenges (financial and labour) of navigating the elements at home. To do so, we bring two conceptual approaches into conversation: cultural geographies of home and homemaking, recognising home as a more-than-human process; and architecturally inflected geographies of buildings, attendant to building materials and socio-technical practices of maintenance and repair. Drawing on semi-structured walking interviews with 24 residents of a new coastal housing development in southern Sydney, Australia, the paper examines how coastal conditions and elements accelerate material decay, inciting and directing everyday homemaking practices: both proactive, in material selection, and reactive, in cleaning, repairing, maintaining, and replacing. We conclude by considering the differing economic rationalities of navigating the elements, and subsequent implications for household sustainability.

Co-occurrence patterns of ice-rafted dropstones and brachiopods in the Middle Permian Wandrawandian Siltstone of the southern Sydney Basin (southeastern Australia) and palaeoecological implications

The ecological significance of ice-rafted dropstones in present-day glacial marine benthic environments has received considerable attention from ecologists, but similar studies based on the geological records of dropstones and associated fossils are rare. In this study, we report statistically significant co-occurrences of ice-rafted dropstones with brachiopod shells in multiple stratigraphic horizons at multiple sites from the Middle Permian Wandrawandian Siltstone of the southern Sydney Basin in southeastern Australia. We analysed the distribution patterns of both dropstones and brachiopod-dominated fossil assemblages by using a quadrat-based sampling method and spatial point pattern analysis. It was revealed that the co-occurrences of ice-rafted dropstones and brachiopod shells are not random; rather, they demonstrate statistically significant and stratigraphically recurring associations that are here interpreted to represent dropstone-associated, brachiopod-dominated palaeoecological communities. In these recurring palaeocommunities, the presence of ice-rafted dropstones is considered to have added habitat complexity and heterogeneity to the benthic environment, especially suited to the settlement of brachiopods. In addition, the sinking of dropstones, from floating ice masses through the water column to the silty seafloor, is interpreted to have enriched the nutrient and oxygen supply to the benthic environment, further aiding the flourishing and maintenance of a diverse and stable marine benthic fauna. Supplementary material: Original data collection (Supplementary material 1) and spatial point pattern analysis results of rest quadrats (Supplementary material 2) are available at https://doi.org/10.6084/m9.figshare.c.4101743

Calculated homes, stretched emotions: Unmasking ‘rational’ investor-occupier subjects in large family homes in a coastal Sydney development

Owner-occupation is axiomatic in Australia and other Western housing markets. Amidst financialisation imperatives, the owned house is dually cast as a financial asset and instrument, while simultaneously persisting in its domestic role as ‘home’. This paper investigates emotional performances and accompanying socio-material expressions underwriting the figure of the investor-occupier subject. Ethnographic research was conducted in a new housing development in an increasingly affluent coastal setting in southern Sydney, where 21 households participated in semi-structured walking interviews focusing on purchasing decisions, building a new home, and early homemaking practices. Following the stories of new residents, three themes emerged, around which our analysis is structured: how households articulated overlapping domestic and economic ideals of home; the emotional performance of a calculative investor subject; and how ideals of opportunity and competitiveness became reflected materially in newly built homes. The paper explores moments of suppressed emotional complexity surrounding matters of financial expenditure – unmasking the ‘rational’ investor-occupier. We conclude by exploring what is potentially lost or gained from rewriting financially the emotional cues of the family home.

Hydrocarbon generation potential of a Lower Permian sedimentary succession (Mount Agony Formation): Southern Sydney Basin, New South Wales, Southeast Australia

This research presents a comprehensive approach on the hydrocarbon generation potential applied for the first time on the Lower Permian Mount Agony Formation that is exposed in the southern Sydney Basin, southeast Australia. Thirty mudstone samples were collected and analyzed using different organic geochemical methods such as, Rock-Eval VI-TOC, bitumens extraction, and GC–MS analysis. Attributes such as, quantity, quality and maturity of the organic matter were utilized to estimate the regional source rock potential. The obtained data indicate that the examined samples have poor to good, dominantly gas-prone source-rock potential, and contain a mixed in origin organic matter. The slight predominance of terrestrial organic material is indicated by the low odd to even predominance values, slight predominance of higher n-alkanes over short-chain n-alkanes, OEP25–33, CPI25–33, ACL25–33, and TAR values. Some availability of marine organic material is evidenced by the predominance of intermediate chain n-alkanes and the low n-C19/n-C31 and n-C24+/n-C24– ratios. The analyzed sediments are thermally mature, as suggested by the Tmax, PI, OEP 25–33 and CPI25–33 values, the Pr/n-C17, Ph/n-C18, C30-moretane/C30-hopane, Ts/(Ts+Tm) and C32S/(S+R) ratios, as well as by the C30-moretane/C30-hopane versus Tm/Ts plot. A mudstone-rich, siliciclastic source rock is implied by the C29/C30 hopane ratios and by the Ts/(Ts+Tm) versus 23tricyclic/hopane cross-plot. This research offers original organic geochemical data of a sedimentary succession that was not so far regarded as source rock. This study adds to the knowledge available for the types of potential reserves in the Southern Sydney Basin, which are mostly focused on coal and coal-seam gas resources.

Spatial context in the calculation of gas emissions for underground coal mines

The prediction of gas emissions arising from underground coal mining has been the subject of extensive research for several decades, however calculation techniques remain empirically based and are hence limited to the origin of calculation in both application and resolution. Quantification and management of risk associated with sudden gas release during mining (outbursts) and accumulation of noxious or combustible gases within the mining environment is reliant on such predictions, and unexplained variation correctly requires conservative management practices in response to risk. Over 2500 gas core samples from two southern Sydney basin mines producing metallurgical coal from the Bulli seam have been analysed in various geospatial context including relationships to hydrological features and geological structures. The results suggest variability and limitations associated with the present traditional approaches to gas emission prediction and design of gas management practices may be addressed using predictions derived from improved spatial datasets, and analysis techniques incorporating fundamental physical and energy related principles.

Interplay of tectonism and eustasy during the Early Permian icehouse: Southern Sydney Basin, southeast Australia

This investigation presents an outcrop‐based integrated study of sedimentological analysis and sequence stratigraphy applied to the Lower Permian sedimentary succession in the southern Sydney Basin, Australia. This succession accumulated in several depositional environments and sub‐environments that range from non‐marine (fluvial) to marine (outer shelf), representing the fill of a sedimentary basin that resembles a fault‐bounded, rift basin. The stratigraphic analysis indicates a deepening‐upward trend, and the sequence stratigraphic approach has established that these sediments can be attributed to the lowstand, transgressive, and highstand systems tracts. Lowstand sediments can be defined by fluvial facies that are located between the subaerial unconformity and the maximum regressive surface. Transgressive facies correspond to estuarine, upper and lower shoreface, and inner and outer shelf depositional environments and are located between the maximum regressive and the maximum flooding surfaces. Highstand bottomset sediments are accumulated above the maximum flooding surface and are represented by outer shelf facies. The stratigraphic architecture indicates the development of an almost complete depositional sequence, mainly developed under the control of tectonically induced subsidence, but also influenced by the high sedimentation rates and the high gradient of the inherited topography. Eustatic sea‐level fluctuations were of minor importance during the deposition of the examined sediments.

A new trace fossil assemblage from the Middle Permian Broughton Formation, southern Sydney Basin (southeastern Australia): Ichnology and palaeoenvironmental significance

The Permian-Triassic sedimentary succession of the southern Sydney Basin in southeastern Australia contains a wealth of well-preserved trace fossils that are important for systematic ichnological, palaeoecological, and palaeoenvironmental interpretations. In this study, a new ichnofossil assemblage comprising Macaronichnus, Palaeophycus, Psammichnites, Protovirgularia, Rosselia, and Teichichnus is documented from the tide-influenced shoreface deposit of the Middle Permian Jamberoo Sandstone Member of the Broughton Formation. Two distinct ichnofabrics are recognized: i) the Psammichnites ichnofabric characteristic of the upper–middle shoreface deposit; and ii) the crowded Rosselia ichnofabric (CRI) representing the lower shoreface. The Psammichnites-dominated ichnofabric is interpreted to have resulted from opportunistic behaviours of unknown trace makers, whereas the CRI is interpreted to represent possible strategic behaviours of stress-tolerant polychaetes (e.g., terebellid, spionid, and cirratulid polychaetes) in a distal shoreface with high sedimentation rate. Thus, the Psammichnites–crowded Rosselia ichnofabric succession can be considered to represent a response to an environmental shift from proximal to distal shoreface. As such, this study highlights the utility of these two ichnofabrics as stressed environmental indicators.

Under Construction: How Home-making and Underlying Purchase Motivations Surface in a Housing Building Site

Drawing on material geographies of home, this paper argues researching building sites furthers understandings of home-making, purchase motivations and modes of valuing new homes. The building site is examined through semi-structured walking interviews with 21 households living in a master-planned estate (MPE) under construction in southern Sydney. MPEs are a fitting representative for profiling the intricacies of new build housing developments. In these contexts, the duration of the building site persists; this overlaps with early occupation and creates challenges that are expected and unexpected, brief and enduring. Results are presented in two sections. First, sharing space with builders and new neighbours fractures some expectations of an ideal home. Home-making proceeds by accommodating, both emotionally and physically, the challenges of building sites. The second section shows how residents weigh up home-making challenges alongside anticipated financial reward. This reward is always speculative though, and the building site compounds this: residents take a risk at the outset, managing fears and worries that hinge upon the aesthetic expression of others. Building site experiences are both an example and evidence of home as a process. Housing studies should continue to pause at these interstitial moments, towards better grasping the expectations and aspirations of contemporary home-making.

First record of the trace fossil Protovirgularia from the Middle Permian of southeastern Gondwana (southern Sydney Basin, Australia)

LUO, M. & SHI G.R., February 2017. First record of the trace fossil Protovirgularia from the Middle Permian of southeastern Gondwana (southern Sydney Basin, Australia). Alcheringa 0, 000–000. ISSN 0311-5518.This study reports the first examples of well-preserved chevronate trails referable to Protovirgularia longespicata De Stefani, 1885 from the early Middle Permian (Roadian) upper Wandrawandian Siltstone of the southern Sydney Basin, southeastern Australia. The highly meandering trace with closely spaced, papillate chevrons is interpreted to have been produced by the locomotion-feeding behaviour of certain protobranch bivalves in an offshore environment. The dense trails occurring on the upper bedding planes of pebbly siltstone may represent a gregarious lifestyle, where junior and senior individuals of the trace-maker bivalves coexisted while moving within sediments. The Wandrawandian Protovirgularia also represents the first known occurrence of this ichnotaxon from a glaciomarine environment in the Permian eastern Gondwana. The global record of Protovirgularia occurrences suggests that these trails had a wide environmental distribution since the Cambrian, and there is no obvious difference in the environmental distribution of Protovirgularia after the Permian‒Triassic transition.Mao Luo [m.luo@deakin.edu.au] and G.R. Shi [guang.shi@deakin.edu.au], Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood Campus, 221 Burwood Highway, VIC 3125, Australia.

Middle Permian paleomagnetism of the Sydney Basin, Eastern Gondwana: Testing Pangea models and the timing of the end of the Kiaman Reverse Superchron

Paleomagnetic and geochronologic data from the eastern margin of Gondwana have been obtained from the Gerringong Volcanics in the southern Sydney Basin, Australia. The corresponding paleomagnetic pole at 56.9°S, 154.8°E (N=131; A95=9.1°) has a 40Ar/39Ar plagioclase plateau age of 265.05±0.35 [0.46] Ma from the Bumbo Latite, and overlaps with recent radio-isotopic and paleomagnetic results published from Western Gondwana. The long-documented inconsistency between Middle Permian Eastern and Western Gondwanan paleomagnetic datasets is most likely an artefact of a lack of reliable paleomagnetic data from Eastern Gondwana for this period. A number of well-dated and recently published ca. 265Ma paleomagnetic results from Gondwana and Laurussia are shown to be consistent with the Wegenerian Pangea A configuration, with a loose N-S fit of the continents for the Middle Permian. The lack of crustal overlap negates the need for a Pangea B configuration, which if valid must have been assembled to Pangea A by ca. 265Ma.The reverse polarity Bumbo Latite was sampled from the Kiaman type-section located in the southern Sydney Basin. Three cases of normal polarity were detected in the overlying Saddleback, Dapto, and Berkeley Latites, previously assigned to the Kiaman Reverse Superchron (KRS). We review KRS-aged magnetostratigraphic data and propose that an age assignment of 265Ma most likely represents the termination of the non-reversing field, with longer stable intervals of normal polarity recorded and able to be correlated globally.

Predation on small passerines by the Spangled Drongo Dicrurus bracteatus

ABSTRACT The Spangled Drongo Dicrurus bracteatus, a partly-migratory passerine, was observed in bushland remnants in southern Sydney. Here, we report two incidents of Spangled Drongos hunting and feeding on small passerines from mixed flocks. One was seen chasing a Spotted Pardalote Pardalotus punctatus, consuming much of the carcass in 17 minutes. Another was seen ambushing a Brown Gerygone Gerygone mouki from a hunting perch. Interesting insights include proceeding to pluck feathers before the prey was dead and ingesting some of the feathers.

Petrology, Diagenesis and Reservoir Quality in the Hawkesbury Sandstone, Southern Sydney Basin, Australia

Petrography of the Hawkesbury Sandstone was described by thin section, scanning electron microscope and Xray diffraction techniques. Quartz is dominant in the Hawkesbury Sandstone which contains very minor feldspar, lithic grains, mica and heavy minerals. The Hawkesbury Sandstone is quartzarenite to sublitharenite. Quartz includes monocrystalline and polycrystalline grains while the feldspar includes both K-feldspar and plagioclase. Volcanic, sedimentary and chert rock fragments are present. Thin section porosity occurs in the Hawkesbury Sandstone, particularly the coarse-grained deposits. Primary porosity is more common than secondary porosity in the Hawkesbury Sandstone. Thin sections and scanning electron microscopy were used to describe diagenetic alterations and their influence on porosity in Hawkesbury Sandstone. These diagenetic alterations include compaction, quartz overgrowths, authigenicclay minerals and carbonate cement. Compaction occurred in the Hawkesbury Sandstoneduring throughout diagenesis. The influence of chemical compaction on thin section porosity was greater in the Hawkesbury Sandstone. Quartz overgrowths are common in the Hawkesbury Sandstone where they have a strong influence on porosity. Authigenic clay minerals are the widespread in the Hawkesbury Sandstone filling pores and occurring as grain-coatings on detrital and authigenic grains. Where they coat quartz grains they preserve porosity by preventing growth of quartz overgrowths. Pore-filling carbonate cement reduced porosity whereas dissolution of carbonate resulted in secondary porosity. Dissolution of unstable feldspar and lithic grains is absent in the Hawkesbury Sandstone. The Hawkesbury Sandstone is characterized by primary and secondary porosity, thus it has good groundwater storage and flow potential. Medium- and coarse-grained sandstone beds are common in the Hawkesbury Sandstone but it shows vertical variations in porosity. A few impermeable shale and siltstone units occur in the Hawkesbury Sandstone forming local confining layers.

Provenance, diagenesis, tectonic setting and geochemistry of Hawkesbury Sandstone (Middle Triassic), southern Sydney Basin, Australia

Provenance, diagenesis, tectonic setting and geochemistry of Hawkesbury Sandstone (Middle Triassic), southern Sydney Basin, Australia

Geochemical Assessment of Trace Element Pollution in Surface Sediments from the Georges River, Southern Sydney, Australia

Measurement of elevated trace elements is an important component of environmental assessment and management of estuarine marine sediments in systems adjacent to concentrated human activity. The present study surveys the estuarine sediments in selected tributary bays, creeks, and the upper segments of the Georges River system, NSW, Australia, which flows into the Tasman Sea through Botany Bay. A total of 146 surface sediment samples were analysed by X-ray fluorescence. Potential pollution of sediments was evaluated using potential load index, modified degree of contamination, and potential ecological risk index. The spatial distribution of trace elements varies between sites. Variable sources of contamination, including runoff from catchment areas, and emissions from watercraft and boatyards are contributing sources. Bay morphologies and their interactions with catchment and tidal flows play significant roles in the distribution of trace elements. The greatest concentration of trace elements occurs around discharge points and in the inner parts of bays that have high percentages of mud particles and organic matter. The lowest contamination by trace elements was found in sandy sediments along the shoreline and edges of the bays. Trace element distributions decline in concentration in residential-free areas and reach background levels in deeper sediment cores. The concentrations of trace elements were controlled by discharge points from the catchment area, marine boat activities, bay morphology, and sediment types (sand, silt, and clay). The highest pollutant concentrations are the result of past legal, but uncontrolled, discharge of waste from manufacturing into Salt Pan Creek.

An explorative qualitative study on acceptability of physical activity assessment instruments among primary care professionals in southern Sydney.

BackgroundThere are a substantial number of instruments for primary-care clinicians to assess physical-activity (PA). However, there are few studies that have explored the views of clinicians regarding comparative acceptability and ease of use. A better understanding of how clinicians perceive instruments could help overcome barriers, and inform future interventions. This study explored the acceptability of five PA-assessment instruments amongst a sample of Australian primary-care clinicians, including family-physicians (FP) and practice-nurses (PN).MethodsA purposive sample of FPs (N = 9) and PNs (N = 10) from eight family-practices in southern Sydney consented to participate. Stage-1 involved semi-structured interviews with participants to select preferred instruments. An analysis of the two preferred instruments was conducted as Stage-2, to identify differences in instrument purpose and content. Stage-3 involved participants using the two instruments, selected from Stage-1, for 12-weeks. At the end of this period, semi-structured interviews were repeated to explore clinician experience.ResultsClinicians indicated preferences for the GP-Physical-Activity-Questionnaire and 3-Questionnaire Physical-Activity-Questionnaire. These instruments demonstrated distinct variations in content, theoretical orientation, and outcome measures. Reasons for preference included; variations in individual clinician PA levels, knowledge in PA-assessment and instrument features.ConclusionFindings demonstrated two instruments as preferred. Reasons for preference related to internal characteristics of clinicians such as variations in the level of individual PA and external circumstances, such as instrument features.

Lead isotope fingerprinting used as a tracer of lead pollution in marine sediments from Botany Bay and Port Hacking estuaries, southern Sydney, Australia

Anthropogenic lead has been released into environmental ecosystems via human activities; essentially from mining, smelting of lead, leaded gasoline and industrial activities. In order to explore the source apportionment and historic record of lead pollution in the marine sediments, concentration of lead was determined from the Botany Bay and Port Hacking estuaries, south of Sydney, Australia. Areas with the highest concentrations of lead in the sediment samples were analysed by inductively coupled plasma-mass spectrometry (ICP-MS) for lead isotopes to effectively identify the metal contamination source. In addition, other sediment samples were collected from cores at 40 cm depth to represent the natural background composition. The study found that the total lead in the tested marine sediments varied from 75.6 mg/kg to 582.2 mg/kg. The 206Pb/204Pb showed a decline towards the current surface sediment. Assuming that the natural background source of lead remains the same in terms of both isotopic signature and accumulation rate, the decline in 206Pb/204Pb indicated a rise in the contribution of old lead to the sediment, mainly from gasoline fumes (car and boat exhausts) and paint. This is because the samples came from close to water discharge points which have concentrated the catchment lead via stormwater runoff.