Heavy Metals in Sediments of the Upper Hawkesbury‐Nepean River

There is little published information on heavy metals in surficial sediments of the upper Hawkesbury‐Nepean River in central New South Wales, Australia. In the current investigation, the fine fraction (<62.5 µm) of 90 sediment samples taken from this section of the river was analysed by flame‐Atomic Absorption Spectroscopy for nine heavy metals (Ag, Cd, Pb, Zn, Cu Co, Fe, Ni and Mn) to determine background and enrichment. Sediment in the upper Hawkesbury‐Nepean River is not heavily polluted by heavy metals. Maximum enrichment over background for Ni and Ag, Cd, Pb, Zn, Cu and Mn is 3x, 5.7x, 6x, 6.7x, 12x and 13.6x, respectively. Mean heavy metal concentrations for this, the upper section of the river, are about half the mean values for the Hawkesbury River between Windsor and Broken Bay in the lower, estuarine section of the river. The highest Cu, Pb and Zn concentrations (214, 108 and 334 mg kg^?1, respectively) occur in surficial sediments in Peachtree Creek at Penrith and the Nepean River near Jacksons Lane, Castlereagh. These metal concentrations are possibly associated with industrial activity at Penrith. Two of the six sewage treatment plants on the upper Hawkesbury‐Nepean River are associated with high metal concentrations (Cu, Zn, Fe and Mn) in sediments, that is, the West Camden and Penrith sewage treatment plants. Other possible sources of heavy metals are coal mining and washing which occurs at several places in the upper catchment. The highest Cd, Co and Fe concentrations (1.7, 27.6 mg kg^?1 and 4.81%, respectively) were found in sediments 400 m downstream of the Nepean Dam and the highest concentrations of Ni and Mn (54 and 790 mg kg^?1, respectively) were located in sediment from the Nepean River at Moresby Hill Road Bridge, near Robertson and at the Avon Dam Road Bridge. The source of these metals is unknown.     

Diatom and dinoflagellate assemblages of the Hawkesbury River,N.S.W., over the last two centuries: evidence for changes in hydrology

Diatom and dinoflagellate cyst analysis of a 77 cm long sediment core from Cowan Creek, Hawkesbury River estuary, N.S.W., revealed changes in the catchment hydrology over the last 266 years. High abundances of the freshwater/brackish diatom genus Cyclotella at the base of the core imply sustained periods of reduced salinity that now no longer occur. Reduction of freshwater flow after approximately circa 1800 (60 cm) has allowed the development of marine planktonic diatoms Thalassiosira spp.,Ditylum brightwellii, Rhizosolenia setigera, Pseudo-nitzschia pungens and Chaetoceros spp. Benthic diatom diversity has remained relatively unchanged. The toxic dinoflagellate Gymnodinium catenatum, although identified in a cyst survey in April 1995, was not found in the sediment cores. Changes in dinoflagellate assemblage are consistent with the effects of increasing urbanisation and eutrophication.     

The Impact of Urbanisation on the Bed Sediments of South Creek,New South Wales

The textural and geochemical characteristics of the bed sediments in South Creek are examined. The bed substratum in the urbanised reaches differs from that of the rural reaches, in terms of the volume and size of the fine matrix sediment and the concentration of heavy metals. The impact of urbanisation on the river-bed sediment is variable, with less matrix than ‘expected’ within the substratum of the urban reach and more than ‘expected’ in the below urban reach. The urban matrix sediment is also significantly finer in comparison to the rural reach matrix sediment. Heavy metal concentrations within the urbanised matrix sediment are up to 800 times greater than background levels and are considered to be indicative of extreme contamination despite only SO years of urbanisation.     

Estuarine Acidification: Impacts on Aquatic Biota of Draining Acid Sulphate Soils

Acid sulphate soils form when iron pyrite oxidises to sulphuric acid on atmospheric exposure, lowering soil pH below 4. In the Richmond River estuary, northern New South Wales, flood mitigation, drainage works and floodplain excavations have augmented acid sulphate soil formation by increasing pyrite availability for oxidation. These engineering works have facilitated the transport of acidified water and have impeded recovery from tributary acidification. The increased frequency and duration of acidification are associated with elevated concentrations of inorganic monomeric aluminium and dissolved iron, and major iron hydroxide precipitation, with deleterious effects on exposed aquatic biota and habitat. Fish kills and an outbreak of epizootic ulcerative syndrome (EUS) have been recorded from acidified sites in the estuary.     

Trace Metal Distribution Within Marine and Estuarine Sediments of Western Moreton Bay,Queensland, Australia: Relation to Land Use and Setting

This broad‐scale investigation provides an overview of trace metal concentration and distribution within sediments in the subtropical setting of Moreton Bay on the eastern Australian coast. Samples of sediment in one‐metre long PVC cores were collected from the intertidal zone of the western shoreline of the Bay and within its main estuaries. The material is typically silty sand along the Bay shoreline, becoming more clayey within the estuaries. Downcore pH is typically between 7.0 and 8.0, with layers in some cores of pH 6.0 to 7.0. Locally, pH can fall below 5.0 due to pyrite oxidation or exceed 8.0 due to the presence of shell fragments. A comparison with results of similar studies in other highly populated centres in Australia shows that overall the Moreton Bay area sediments have relatively low metal content. Typically, concentrations are two to three times higher in fine‐grained, estuarine sediments than in sandy material along the Bay shoreline. Compared with Australian and New Zealand Environment and Conservation Council Guidelines for metal concentrations in sediments, the elements most commonly elevated and warranting further assessment are Ni, Hg, Pb, Zn, and occasionally Cd, As and Cr. The highest metal concentrations are found in estuaries, close to more populated or industrialised areas, notably along the Brisbane River. Overall, the distribution of metals in unconsolidated material is controlled by (a) the heavy metal affinity for Fe‐ and Mn‐rich oxidised sediments, (b) grain size, (c) background concentrations in local rocks, and (d) conditions of weathering and deposition. For example, natural elevation of Fe occurs in marine sediments adjacent to areas of Tertiary basalts and this has produced a relative increase in a number of trace metals in those sediments. Typically, trace metals correlate well with Al, and with Fe and Mn oxyhydroxides. The results of this study show that in the western Moreton Bay region, natural controls have the major influence over metal distribution; although urban and industrial inputs exist, for much of the area they are secondary. The main sources of introduced trace metals are presumed to be light industry (such as maritime and port facilities, petroleum refineries and storage, manufacturing and chemical processes), landfills, agriculture and intensive fertilising (for example, golf courses) as well as the composite effect of urban centres. Overall, higher concentrations of metals are closely related to intense development. If specific locations are targeted for focussed sampling, elevated concentrations of metals are likely to be found locally.     

Response to Wet Season Rainfall of an Alluvial Aquifer System in the Lower Herbert Floodplain,Queensland, Australia

Australia is one of the world's largest exporters of raw sugar. The lower Herbert River floodplain, one of the four main cane growing areas in Queensland, is subject to extremes of rainfall. Some areas are prone to waterlogging, which can lead to reductions in cane and sugar yields. This paper examines the risk of waterlogging and the role of surface drains in the Ripple Creek area, a subcatchment of the lower Herbert River floodplain. Following above‐average rains at the onset of this study, a perched water table developed and remained for the duration of the 19 month study. The responses of the perched watertable and a deeper semi‐confined aquifer following rainfall are examined. The rapid response of the perched water table following rainfall is attributed to the shallow depth of the water table, with soil properties exerting a dominant influence on hydrograph response. In the second year of the study, after above‐average rainfall, the water table of the deeper aquifer was on average 1 m higher than during the former months of the study. This trend, however, did not occur in the perched water table, and this is attributed to the efficiency of the surface drainage network.     

古代香港树皮布文化发现及其意义浅释

环珠江口一带的大湾文化中发现的树皮布石拍是中国大陆目前所知唯一年代最早,可靠性最强的与树皮布技术相关的资料。环珠江口树皮布文化很可能是全球树皮布文化的源头。     

The Evolution of a Holocene Estuarine Barrier on the Coromandel Coast,New Zealand

Whitianga Harbour on the Coromandel Peninsula, North Island, New Zealand is fronted by a broad sandy barrier composed of linear beach ridges. The barrier developed through a process of rollover as sea level rose in the early Holocene with shelly sandy sediment washed inland over estuarine muds. These overwash deposits are present to 3 m below sea level in the back barrier area. Once sea level stabilised and barrier rollover had ceased the barrier continued to prograde in a series of beach ridges. The back barrier area is characterised by estuarine muds, overlain by splay and overwash deposits that are reworked by fluvial and tidal channels. The initial flooding of the estuary occurred at around 7350–7225 years cal BP, reaching modern levels by 6894–6729 years cal BP at the earliest. Infill was rapid as evidenced by estuarine species (crustaceans and bivalves) preserved in life position. From ～6000 years BP to present, the estuary is characterised by tidal and fluvial reworking, suggesting that modern sediment inputs are bypassing the estuary.     

Competition and conflict in the Upper Belize River Valley: Insights from the ancient Maya minor center of Callar Creek,Belize

Political relationships typically entail competition and conflict. Within the ancient Maya world, the Upper Belize River Valley (UBRV) offers one example of an arena of intense political contestation, and recent investigations at the minor center of Callar Creek offer insights into this complex and occasionally antagonistic political landscape. During the Late and Terminal Classic periods (a.d. 600–900), for example, those living at the Callar Creek center appear to have affiliated themselves with the larger center of Buenavista, but not to have developed political ties with those in surrounding hinterland communities. Indeed, Callar Creek provides an example in which the political fortunes of a minor center and its surrounding hinterlands followed divergent paths. Furthermore, a termination event suggests that part of the Callar Creek center was purposefully destroyed by adversaries in the Terminal Classic period, and that discordant relationships in the UBRV at times turned violent.     

Marine trophic levels targeted between AD 300 and 1500 on the Georgia coast,USA

The marine trophic levels targeted during Swift Creek (AD 300–700) and Savannah (AD 1200–1500) occupations at the Cathead Creek site (9Mc360) and at two sites from the Kings Bay Locality (9CAM171a, 9CAM177), coastal Georgia, USA, differ in a consistent temporal and spatial pattern. Vertebrate and invertebrate remains from these three coastal sites contain similar suites of estuarine animals. However, Swift Creek peoples at these distinct hydrological settings obtained more biomass from fishes and less from molluscs compared to the subsequent Savannah occupants. The two Swift Creek faunal collections are less rich, more diverse, and more equitable than the two subsequent Savannah collections regardless of location. Furthermore, the mean trophic level is higher in the Swift Creek collections compared to the Savannah ones at both locations. These observations apply to both biomass and Minimum Number of Individuals. These differences likely are defining characteristics distinguishing the Swift Creek and the Savannah economies. More research is needed to determine the extent to which these temporal and spatial patterns are attributable to environmental and cultural variables.     

Constructing Water Shortages on a Huge River: The Case of Shanghai

Shanghai is located on the world's third largest river (by volume). Yet it faces the risk of shortages of drinking water. Many decisions and environmental characteristics have contributed to this threat. First, Shanghai has become dependent on water brought into the municipality by rivers. Second, it has become increasingly reliant on water from the Changjiang (Yangzi River), principally in order to control the levels of pollution in the water that enters its treatment plants. Third, for reasons associated with inter‐provincial administrative arrangements, the city's water intakes are located within the municipality, within the estuary zone and subject to tidal intrusions of salt water. Fourth, at high tide and when the Changjiang's discharge is low, salt intrudes far into the estuary, beyond the current water intakes. If sea levels rise, these intrusions will become more pronounced. Fifth, large‐scale central government infrastructure projects (such as dams and the South‐North Transfer) are altering the hydrological characteristics of the river. Such projects raise the probability of salt water intrusions into the water intake zone. The Shanghai and central governments have thus made a series of decisions that, taken together, have led the municipality to rely on a source of drinking water that is increasingly unreliable and subject to the risk of shortages due to salt water intrusions. Why these decisions have been made – independently – is an important problem for those who would understand the provision of water for cities and the practical efficacy of Chinese governance systems.     

Mid‐Holocene Development of Mangrove Communities Featuring Rhizophoraceae and Geomorphic Change in the Richmond River Estuary,New South Wales,Australia

This paper describes the hitherto unreported occurrence of mid‐Holocene mangrove deposits in the Richmond River estuary, southeastern Australia, thereby providing evidence for changes in the distribution and composition of mangrove communities within a subtropical estuarine system during the Holocene. Stratigraphic, radiocarbon and palynological evidence indicates that widespread development of mangrove communities took place in the upstream reaches of the Richmond River estuary during the period 7000 to 6000 years BP. These communities maintained their habitat through substrate aggradation under the conditions of a moderate sea‐level rise, in contrast to other estuaries within the region, which generally experienced the submergence of intertidal substrates. Mangrove species belonging to the family Rhizophoraceae, most likely Bruguiera gymnorrhiza and Rhizophora stylosa, dominated these communities, in strong contrast to contemporary communities, which are dominated by Avicennia marina. Moreover, these mid‐Holocene communities were located a considerable distance upstream of the contemporary occurrences of Rhizophoraceae species within the estuary. The changes in the spatial distribution and composition of mangrove communities parallel the large‐scale evolution of the estuary driven by sea‐level variation. Shallow, buried Pleistocene terraces probably contributed to the regionally unique aggradational response of the mangrove communities and their substrates to a sea‐level rise during mid‐Holocene times.     

1世纪至20世纪中期上荆江流域河道与水环境变迁——基于荆江洪水位历史变迁的考察

清中叶以降,清宫档三汛(桃花汛、伏汛、秋汛)安澜奏本中所见荆江洪水位开始日益上涨,咸丰、同治年间,藕池、松滋决口向洞庭湖分流后,水势稍有缓解,至光绪年间复又急速抬升。不断上涨的洪水位对江北入江河流造成了两方面影响: 其一为河道的变迁,其二为水环境的变化。在沮漳河流域,涉及长江百里洲的变迁,沮漳河入江口的变动,长江主泓迁移,下百里洲靠岸及洲尾东摆引发沮漳河下游延长,以及山水、江水相互顶托造成水环境淤积。在玛瑙河流域,则表现为荆江洪水位抬升对河水的顶托现象,导致入江尾闾沼泽化。     

Dendrochronological Flood-frequency Analysis: An Australian Application

Dendrochronological studies have received little attention in Australia and it appears that the methodology is not well understood. This paper describes dendrochronological techniques available in riparian environments and applies them to a small reach of the Hawkesbury River. Results of field investigations into the relationships between flooding and associated tree-ring variability were used to reconstruct partial duration flood-frequency data. The ring-width chronologies of 39 trees were transformed into three indices that made interpretation with respect to flooding possible: (1) a width-index: (2) an annual-sensitivity (AS) index; and (3) a tilting vector. It was assumed that floods would either suppress growth or alter the annual distribution of new wood about the tree bole. Width-indicies and tilting vectors provided the most reliable flooding information. Much reduced growth rates at low elevations supported initial hypotheses and led to the establishment of a relationship between growth-rate and frequency of inundation. The reconstructed flood-frequency curve closely matched the historical data-set although underestimation occured at higher levels due to limited sample size. Analyses indicate that dendrochronological investigations of exotic riparian trees provide detailed flooding information, but techniques may also be used to provide minimum dates of fluvial landforms and date recent channel changes.     

Spatial and Temporal Patterns of Recreational Angling Effort in a Warm‐Temperate Australian Estuary

Among the critical issues for the management of estuarine fish resources is the need to adequately identify the extent of use by recreational fishers, and the allocation of the resource between recreational and commercial users. Recreational anglers in estuaries often target a similar range of estuarine fish species to commercial fishers. Prior to the declaration of ‘recreational fishing havens’ (estuarine waters closed to commercial netting but remaining open to recreational angling) in many New South Wales (NSW) estuaries in May 2002, the estuary of the Manning River on the central NSW coast supported the tenth most productive commercial estuarine net fishery in the State. To quantify the recreational angling effort in the Manning River estuary, progressive counts were made of shore‐based and boat‐based anglers from a small power boat from June 2001 to May 2002. Sample days (eight per month) were chosen in a stratified random fashion, taking into account the proportions of weekends, public holidays and school holidays in each month. The total recreational angling effort exerted on the estuary for the 12‐month period was 144 892 ± 3248 angler‐hours, indicating a low to medium effort compared to other NSW estuaries of similar size. Over half of the effort was exerted in the section nearest the northern entrance at Harrington. There was relatively little variation in shore‐based angling effort throughout the year, whereas boat‐based fishing increased markedly in summer. Months that coincided with NSW school holidays were most popular, especially January. More recreational fishing effort was exerted in the afternoons than in the mornings during winter, but this trend was reversed in summer. Although daily effort was much higher on weekends than weekdays, the total cumulative effort was generally similar, due to the greater number of weekdays in the year. Pilot studies of catch per unit effort indicate that the recreational catch in the Manning River estuary is probably small compared to the pre‐closure commercial catch. Therefore management strategies aimed at limiting the recreational catch are likely to have minimal impact on fish stocks in the estuary when compared with regulation of the commercial sector.     

CORE ELEMENTS AND LAYOUT CLASSES IN SWIFT CREEK PADDLE ART

Our work here extends a study in which we identified a set of task models used by early Swift Creek artisans to produce paddle designs. Reconstructed procedures for early bandwork compositions highlighted the importance of the placement of guide points and guidelines to the final product as well as the hierarchal nature of the production sequence, leading to the realization that designs can be profitably classified by the geometry of these initial steps. In this paper, we examine two layout classes defined from observations across some of the more common core elements in the Swift Creek design corpus. We then seriate the most common of the core elements, the Omega, by virtue of variation in its visual characteristics. We draw on the stratigraphic sequence at Fairchild’s Landing (9SE14), Seminole County, Georgia, as a test of the core-element seriation and discuss developmental differences in the Omega between two prolific Swift Creek regions, the lower Chattahoochee River of southwestern Georgia and southeastern Alabama and the lower Ocmulgee and upper Satilla rivers of central and south-central Georgia, on the other.     

Pre-Clovis in Texas? A critical assessment of the “Buttermilk Creek Complex”

Lithic artifacts from the lowest strata of the Debra L. Friedkin site, located on Buttermilk Creek in central Texas, have been interpreted as an undisturbed pre-Clovis assemblage (Waters et al., 2011a). Stone tools and debitage were recovered from sediments stratified just below diagnostic Clovis artifacts and dated by OSL to between 13.2 and >15.5 cal kya. Invoking commonly observed cultural and natural site formation processes, we offer an alternative explanation of the “Buttermilk Creek Complex” as a Clovis assemblage in secondary association with the dated sediments.     

From the Piedmont to the Coast: LA-ICP-MS 87Sr/86Sr evidence for short-term,long-distance mobility in the American Southeast

Mounting evidence suggests that the Archaic Southeast shell mound builders had large-scale trade networks and engaged in social aggregations. Here, incremental ⁸⁷Sr/⁸⁶Sr values were measured by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in third molar enamel samples of 11 individuals interred in the Middle Archaic Harris Creek shell burial mound in St. John's River Valley (SJRV), Florida. Results reveal that SJRV residents engaged in short-term, long-distance mobility up to the Piedmont margin and excursions into coastal areas, consistent with direct trading and social gatherings. Two individuals are interpreted as migrants from central Tennessee, suggesting a link to the Ohio River Valley shell mound builders.     

Development of Trigger Levels to Assess Catchment Disturbance on Stream Suspended Sediment Loads in the Magela Creek Catchment,Northern Territory,Australia

Trigger levels for fine suspended sediment (FSS) load in streams are required to identify rainfall-runoff events that have significantly elevated FSS loads, compared with expected background loads, as a result of catchment disturbance. Stream FSS load data collected in the mine-impacted Magela Creek catchment in the wet-dry tropics were used to derive water quality management trigger levels for two approaches – a Before-After-Control-Impact Paired difference design (BACIP) and a regression relationship between observed FSS load and corresponding event discharge characteristics. The results indicate that both the BACIP and regression relationship approaches behave similarly, with similar FSS load events elevated above trigger levels. Notwithstanding this, it is recommended that in order to reliably assess the location and magnitude of a catchment disturbance on FSS load, a combination of BACIP and regression relationship approaches must be adopted. In this study, an event with a FSS load above trigger levels associated with both BACIP and the regression relationship fitted for the downstream site is considered to be significantly elevated as a result of a disturbance within the mine-impacted region. While this technique cannot conclusively determine whether the cause of the disturbance is mine-related or natural (such as fire or bank erosion), it is an efficient statistical method of identifying events that warrant further investigation and management action, if required.     

The Significance of Coastal Processes for Management of the River Murray Estuary

The tidal prism in the River Murray estuary has been reduced by over 85 percent since completion of the barrages in 1940 and regulation has diminished the rate and size of river flows through the estuary. Reduced fluvial flushing has emphasised the dominance of coastal processes at the river mouth. These are expressed in the accretion and stabilisation of a flood-tidal delta, the migration of the mouth, the erosion of Sir Richard Peninsula and the accumulation of new flood-tidal deltaic deposits. Inconclusive studies relating river flow to mouth migration indicate the importance of coastal processes such as littoral drift, tidal flux and sea state, particularly at times of low river flow, in explaining the position and morphology of the mouth. Previous management strategies have failed to consider coastal processes adequately.