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.     

Holocene sulphur-rich palaeochannel sediments: diagenetic conditions,magnetic properties and archaeological implications

Extensive aggregate extraction in the middle Trent valley, England, has revealed a sequence of Holocene palaeochannels associated with nationally important, and predominantly organic, archaeological remains. This paper reports observations of hyper-acidity (below pH 2), high natural magnetism and metallic sphaerules (framboids) in Holocene palaeochannel sediments at two sites in the middle Trent valley. These properties are associated with high natural remanent magnetism which has allowed the successful palaeomagnetic dating of palaeochannel fills at one of these sites (Hemington). These sediment properties are the result of the formation of ferromagnetic iron sulphides, including griegite, under conditions of high sulphur availability (from groundwater) in the presence of metallic ions and organic matter under low redox conditions, with later oxidation producing the extreme natural acidity through oxidation of disulphide (pyrite). These findings explain why, under certain groundwater conditions, alluvial palaeochannel sediments can carry post-depositional remanent magnetisation and be suitable for palaeomagnetic dating. The low pH may also be beneficial in the initial stage of wood preservation and if the sediments remain waterlogged, but probably not retard decomposition after drainage and acidification, a process that is increasingly being recognised as a threat to archaeological sites in wetland environments.     

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.     

Soil erosion and flooding on the eastern South Downs, southern England, 1976–2001

The South Downs in southern England have been farmed for 5000 years: the initial loess cover is now a thin, stony remnant as a result of erosion. During the 1980s, field monitoring of erosion events in an area of 36 km² showed that average rates of erosion are low (0.5–5.0 m³ ha⁻¹ yr⁻¹), but that occasional storms result in losses of over 200 m³ ha⁻¹ yr⁻¹ on individual fields. On soils that are only 15 cm thick, such rates pose a threat to future farming. Almost all recent erosion has been on fields of winter cereals, which are bare in the wet autumn period. Of greater significance in the short term are the effects of soil-laden runoff (or muddy floods) on urban areas. Flood damage to property has been a regular event since the conversion of this area to winter cereals in the 1970s. Soil conservation measures have been negligible and flood protection has consisted mainly of engineering works and limited land-use change at sites where property damage has occurred. Conversion to grass under the Set Aside, and an Environmentally Sensitive Area (ESA) scheme, could be an effective soil conservation and flood protection approach. In the longer term, increasing stoniness of soils, the economic incentives for arable farming in marginal areas, and the success of legal proceedings relating to flood damage, will determine the future of erosion on the South Downs. Current farming systems clearly are unsustainable and would become more so under future climates without substantial site-targeted land use change.     

Bridging theoretical gaps in geoarchaeology: archaeology,geoarchaeology, and history in the Yellow River valley,China

While geoarchaeology as a practice within archaeology grew out of many historical roots, a major role has been the explication of site formation processes and site-level contextual analysis. In recent years, geoarchaeological research has branched out to encompass larger geographic scales, and to play a greater role in environmental archaeological investigations. This paper argues that geoarchaeology has a great deal to contribute to the understanding of human history and to archaeological theory through the application of multiscalar approaches that place human behavior in a physical, environmental and ecological context and by creating linkages between physical processes and human responses. We use geoarchaeological data from the Yellow River valley to show that drainage/irrigation canal and bank/levee building had commenced in the lower reaches by ca. 2900–2700 cal B.P. The emphasis on flood plain flood control infrastructure was a result of long-term increases in sedimentation caused by large populations farming with increasingly efficient technologies in the fragile environments of the Loess Plateau. Ever increasing sedimentation set in motion a cycle of further investment in flood control works eventually leading to a massive flood catastrophe in the first 20 years of the first millennium A.D. as the Yellow River exceeded natural and human geomorphic thresholds that constrained it in its previous course. These floods arguably triggered the social and political events that brought down the Western Han Dynasty but the root causes are clearly more complex. Geoarchaeology thus contributes to an understanding of the multiple causes and consequences of large-scale social and political collapse.     

Barite–pyrite mineralization of the Wiesbaden thermal spring system, Germany: a 500-kyr record of geochemical evolution

Barite–(pyrite) mineralizations from the thermal springs of Wiesbaden, Rhenish Massif, Germany, have been studied to place constraints on the geochemical evolution of the hydrothermal system in space and time. The thermal springs, characterized by high total dissolved solids (TDS) contents and predominance of NaCl, ascend from aquifers at 3–4 km depth and discharge at a temperature of 65–70°C. The barite–(pyrite) mineralization is found in upflow and discharge zones of the present‐day thermal springs as well as at elevations up to 50 m above the current water table. Hence, this mineralization style constitutes a continuous record of the hydrothermal activity, linking the past evolution with the present state of this geothermal system. The sulphur isotope signatures of the mineralization indicate a continuous decrease of the δ³⁴S of sulphate from +16.9‰ in the oldest barite to +10.1‰ in the present‐day thermal water. The δ³⁴S values of barite closely resemble various recently active thermal springs along the southern margin of the Rhenish Massif and contrast strongly with different regional ground and mineral waters. The mineralogical and isotopic signatures, combined with calculations based on uplift rates and the regional geological history, indicate a minimum activity of the thermal spring system at Wiesbaden of about 500 000 years. This timeframe is considerably larger than conservative models, which estimate the duration of thermal spring systems in continental intraplate settings to last for several 10 000 years. The calculated equilibrium sulphur isotope temperatures of coexisting barite and pyrite range between 65 and 80°C, close to the discharge temperature of the springs, which would indicate apparent equilibrium precipitation. Kinetic modelling of the re‐equilibration of the sulphate–sulphide pair during water ascent shows that this process would require 220 Myr. Therefore, we conclude that pyrite is formed from precursor Fe monosulphide phases, which rapidly precipitate in the near‐surface environment, preserving the isotope fractionation between dissolved sulphate and sulphide established in the deep aquifer. Equilibrium modelling of water–mineral reactions shows slight supersaturation of barite at the discharge temperature. Pyrite is already strongly supersaturated at the temperatures estimated for the aquifer (110°C) and processes in the near‐surface environment are most probably related to contact of the thermal water with atmospheric oxygen, resulting in formation of oxidized intermediate sulphur species and precipitation of Fe monosulphide phases, which subsequently recrystallize to pyrite.     

A Role for Geomorphology in Integrated Catchment Management

Catchments (watersheds) are integrated through water movements. Water moves sediments; and the translocation of materials has geomorphic and pedological responses. Fertiliser and pesticide residues and other toxic substances are also transported by water, in solution and attached to sediment particles, affecting various ecological components of catchments. The insertion of pollutants is directly caused by land‐use practices. In turn, land uses are influenced by the pedo‐geomorphology of the catchments (uplands, valley sides, flood plains and terraces, spurs and hollows, convexities and concavities; position in the upper, middle or lower catchment; and by catenary relationships). Therefore catchment management must deal with interrelationships amongst human activities and various geomorphic elements. Several case study examples from southwestern Australia demonstrate the importance of geomorphology in catchment management. They include: rates of hillslope erosion and translocation of P in micro‐catchments within a drainage basin context; stream salinisation; accumulation of heavy metals in stream sediments; geomorphic elements influencing the spread of weeds and the erosion of access tracks; and some relationships between valley‐side land uses and stream morphology. The incorporation of these and other issues in a management strategy is then illustrated. Complex skills are involved in producing and implementing a management strategy, including but extending well beyond those of the geomorphologist.     

Caesium-137 as an indicator of geomorphic processes in a drainage basin system

Caesium-137 from fallout from nuclear weapons tests is adsorbed on fine sediments and becomes an effective tracer. It is hypothesised that within a drainage basin, sites undergoing little or no erosion accumulate ¹³⁷ Cs in their upper layers; cultivated soils will have ¹³⁷ Cs uniformly distributed within the cultivated layer; eroded soils, cultivated or not, will have relatively less ^l37 Cs, depending on the severity of erosion. Accumulated sediments will have characteristic ¹³⁷ Cs profiles reflecting temporal fallout variations and sedimentation history. This hypothetical model is largely confirmed by results from Maluna Creek basin, where erosion and accumulation of sediments has taken place. Soils under viticulture have about one third the ¹³⁷ Cs content of soils with grass cover, indicating more severe erosion under cultivation. Caesium-137 profiles in alluvial fan and flood plain deposits correlate with sediment layers and known cultivation history.     

The Pre-Settlement Vegatation of the Western and Central Wimmera Plains of Victoria,Australia

Historical records indicate that the fertile soils of the western and central Wimmera Plains of Victoria, Australia formerly supported grassy woodlands on rises and flats, and grasslands on shallow depressions and clay plains. Soil type and micro-relief appear to have been the major factors that determined the distribution of these communities. Burning of the woodlands by Aborigines may have contributed to their open grassy nature. The few ungrazed remnants of Buloke (Allocasuarina luehmannii) woodland support a suite of species that are absent from or uncommon in other Buloke woodland remnants in the region. This work demonstrates that in districts where little intact native vegetation remains, investigation of the distribution and floristic composition of the pre-settlement vegetation can provide useful information for the maintenance and restoration of remnant vegetation.     

Principles of a Landscape Classification

A classification of natural landscapes based on a combination of historical-genetic and structural criteria is offered. The classificatory categories of a higher order are based on genetic and spatial associations of landscapes; the lower taxonomic entities are based largely on internal landscape structure. The taxonomic entities range from division to subspecies. The earth's landscape sphere is first broken down into divisions of terrestrial and water landscapes. Divisions fall into systems based on zonal differences in the heat and water balance (subarctic, boreal, subboreal, etc.). Systems fall into classes (plains and mountain landscapes), and classes break down into groups of landscapes based on geochemical and moisture criteria (eluvial, hydromorphic, etc.). Groups fall into types on the basis of bioclimatic and soils criteria (wooded steppe, steppe, desert etc.). Types break down into genera on the basis of genetic landform types (alluvial plains, colian landforms, etc.). Finally, the genera fall into species and subspecies on the basis of dominant and subordinated morphologic units known in Russian as urochishche. Examples of steppe plains genera might be gently rolling sandy plains with feathergrass on dark chestnut soils, or level plateau with a mantle of loam and fascue grass on dark chestnut carbonate soils.     

Channel Adjustment Following the Crossing of a Threshold: Tarcutta Creek,Southeastern Australia

Historical records indicate that the fertile soils of the western and central Wimmera Plains of Victoria, Australia formerly supported grassy woodlands on rises and flats, and grasslands on shallow depressions and clay plains. Soil type and micro-relief appear to have been the major factors that determined the distribution of these communities. Burning of the woodlands by Aborigines may have contributed to their open grassy nature. The few ungrazed remnants of Buloke (Allocasuarina luehmannii) woodland support a suite of species that are absent from or uncommon in other Buloke woodland remnants in the region. This work demonstrates that in districts where little intact native vegetation remains, investigation of the distribution and floristic composition of the pre-settlement vegetation can provide useful information for the maintenance and restoration of remnant vegetation.     

Quartz OSL dating of sand dunes in Ghaggar Basin, northwestern India

Several studies have used luminescence dating to investigate sand mobilization activity in extreme western areas and the southern margin of the Thar Desert, India. However, room exists for a chronology of sand profiles for the northern margins of the Thar Desert. The Ghaggar River flood plain at Rajasthan, northwestern India, in the northern margin of the Thar Desert, is bordered by sand dunes. Elucidation of the environmental changes of the Ghaggar Basin requires knowledge of many aspects of sand dune formation. We measured optically stimulated luminescence (OSL) using the single aliquot regenerative-dose (SAR) protocol for sand of eight palaeo-dunes and two flood silts of both sides of the present Ghaggar Basin and Chautang Basin flood plains. Their OSL ages were obtained respectively, as 15–10 ka or 5 ka, and 9–8 ka. Results of this study reinforce the hypothesis that sand dune deposition had started or had already been completed by 15‐10 ka. Aeolian deposition was subdued by enhanced moisture during 9–8 ka. Our interpretation is that, at least since 5 ka, the scale of the flood plain of the Ghaggar River has remained equivalent to that of the present day.     

Household economic resilience to catastrophic rainstorms and flooding in a Chinese megacity

Megacities situated on flood plains face escalating risks of waterlogging and inundation. Tianjin is one of these megacities in China where residents are exposed to these risks and not well prepared for their consequences. Government policies should support the most vulnerable and less resilient groups. This study can inform policy‐making by identifying the socio‐economic characteristics of those who are financially better prepared for the consequences of catastrophic rainstorms and flooding. A structured questionnaire survey was administered to 332 Tianjin residents. Results confirm that financial conditions crucially determine household resilience to these natural hazards. Lower‐income and less educated urban residents have lower resilient capacity. Weak engagement in the community, including residential committees and other organisations, is related to lower capacity to cope with the economic consequences of extreme weather events. Less resilient groups are therefore those who are subject to urban poverty and have limited social capital. Tianjin and other cities in the developing world require resilience strategies that attend to this segment of urban population.     

The Distribution and Environmental Relationships of Native Grasslands on the Lowland Gippsland Plain,Victoria: an Historical Study

Historical survey plans were studied to document the distribution and ecological relationships of treeless native grasslands on the lowland Gippsland plain, eastern Victoria. Grasslands occupied about 600 square kilometres, mostly in the Sale—Maffra—Heyfield area, which receives about 600 mm mean annual rainfall. All grassland regions have been developed for irrigation farming and not a single remnant is known to survive. Topography and soils appear to be the major factors promoting grasslands. They occurred on flat plains on clay loam and loam topsoils, above a clay subsoil. Burning by Aboriginals probably affected plant composition but appears unlikely to have been the principal factor leading to treelessness.     

The Use of Old Russian Land Survey Data in Geographic Research for Agricultural Purposes

Estate maps dating from the Russian general land survey of 1770–1781 are used to compile a historical map of land types, including cropland, forest, meadow, swamps, etc. The historical map is then compared with a modern soil map and a map of soil-forming parent materials to establish what effect, if any, past land types have had on present soil qualities. It is suggested that the better soils, in terms of drainage characteristics, were selected by man in the earliest stages of cultivation, and that poorer soils were put under the plow only subsequently as the crop area expanded. Some of these poorer soils have reverted, in the meantime, to grazing land. Soils long cleared of forest are found to have a higher carbonate horizon (effervescing with HCI) than soils more recently cleared of forest. The study area is Sapozhok Rayon of Ryazan' Oblast, southeast of Moscow.     

The role of forests in global climate change: whence we come and where we go

Neither the United Nations Framework Convention on Climate Change (UNFCCC) nor the Kyoto Protocol include a satisfying mechanism for reducing the substantial emissions from deforestation which are responsible for about a quarter of global greenhouse gas emissions. It is acknowledged that planting forests, for example through afforestation and reforestation in the Clean Development Mechanism, clearly provides an opportunity to sequester carbon in vegetation and soils. However, it takes decades to restore carbon stocks that have been lost as a result of land-use changes. Reducing the rate of deforestation is the only effective way to reduce carbon losses from forest ecosystems. As negotiations on a post-Kyoto agreement have already started the authors argue that a complete and fair post-Kyoto regime will have to expand existing regulations by creating a framework to encompass all land-use and forest-related changes in carbon stocks. Developing countries administer the majority of the world's environmental resources and provide a vital global public good by maintaining environmental assets. However, with increasing pressure on development and the use of resources, developing countries can hardly be expected to provide these services free. Therefore, they will have to be integrated into a more comprehensive incentive framework which also rewards forestry conservation, sustainable forest management and afforestation. The authors discuss how an incentive system for the protection of forests can be included in a future climate regime. Different design choices are considered and two recent approaches to reward developing countries that avoid further deforestation are compared: the 'compensated reduction of deforestation' approach and the Carbon Stock Approach.     

辽代西辽河冲积平原及邻近地区的湖泊

辽代前期西辽河冲积平原上有许多较大湖泊 ,但辽代后期这些湖泊不见于记载 ,反映了辽代西辽河流域的湖泊与环境有很大变化。辽代独特的人文地理现象——“捺钵”制度 ,与西辽河流域多湖泊有一定关系     

A comprehensive review of hydrocarbons and genetic model of the sandstone‐hosted Dongsheng uranium deposit,Ordos Basin,China

The Dongsheng uranium deposit, the largest in situ leach uranium mine in the Ordos Basin, geometrically forms a roll‐front type deposit that is hosted in the Middle Jurassic Zhiluo Formation. The genesis of the mineralization, however, has long been a topic of great debate. Regional faults, epigenetic alterations in surface outcrops, natural oil seeps, and experimental findings support a reducing microenvironment during ore genesis. The bulk of the mineralization is coffinite. Based on thin‐section petrography, some of the coffinite is intimately intergrown with authigenic pyrite (ore‐stage pyrite) and is commonly juxtaposed with some late diagenetic sparry calcite (ore‐stage calcite) in primary pores, suggesting simultaneous precipitation. Measured homogenization temperatures of greater than 100°C from fluid inclusions indicate circulation of low‐temperature hydrothermal fluids in the ore zone. The carbon isotopic compositions of late calcite cement (δ¹³C_VPDB = ?31.0 to ?1.4‰) suggest that they were partly derived from sedimentary organic carbon, possibly from deep‐seated petroleum fluids emanating from nearby faults. Hydrogen and oxygen isotope data from kaolinite cement (δD = ?133 to ?116‰ and δ¹⁸O_SMOW = 12.6–13.8‰) indicate that the mineralizing fluids differed from magmatic and metamorphic fluids and were more depleted in D (²H) than modern regional meteoric waters. Such a strongly negative hydrogen isotopic signature suggests that there has been selective modification of δD by CH₄±H₂S±H₂ fluids. Ore‐stage pyrite lies within a very wide range of δ³⁴S (?39.2 to 26.9‰), suggesting that the pyrite has a complex origin and that bacterially mediated sulfate reduction cannot be precluded. Hydrocarbon migration and its role in uranium reduction and precipitation have here been unequivocally defined. Thus, a unifying model for uranium mineralization can be established: Early coupled bacterial uranium mineralization and hydrocarbon oxidation were followed by later recrystallization of ore phases in association with low‐temperature hydrothermal solutions under hydrocarbon‐induced reducing conditions.     

The effect of soil conditions on the long-term corrosion of buried tin-bronzes and copper

The object of this work was to relate the corrosion of tin-bronzes to the chemical condition of the soil in which they have been buried, most of them since the Bronze Age. Naturally, it was not easy to obtain recent hoards with their related soils, and considerable reliance had to be placed on recorded finds by taking recent soil samples from sites on which hoards were found over a hundred years earlier. Even so, with the exception of peat, a reasonable relationship appears to exist between the pH of the soil and the state of the metal. Acid soils are aggressive to metals and alkaline soils are benign. In no cases were sulphate reducing bacteria active in promoting corrosion. In the main, peat and peaty soils were benign in spite of their acidity, probably due to the protective action of polyphenols.     

Plantation and village in coastal Guyana, 1887–1969: conflict or complementarity?

This study of livelihood patterns in a single rice village of coastal Guyana from 1887 to the present stresses economic and ecological linkages between the village and nearby sugar cane plantations. In the village of Bush Lot, typically populated by descendants of indentured plantation labourers from India, problems of maintaining drainage and irrigation canals have been compounded by a lack of village labour coordination. Varying yields from the community's ricefields have been affected by recurring drought and flood, so the villagers have never been full-time subsistence farmers. Rather, they have worked seasonally on the nearby plantations to supplement village farming activities. This part-time estate work has tended to inhibit social and political solidarity within Bush Lot. The plantations have coped better with water control than have villages. Nevertheless, the cane estates have depended upon nearby villages for seasonal labour. Although agricultural technology and scale of production have changed dramatically during the psst century, plantations and villages of the Guyanese coastal plain remain closely interlinked.