Assessing the environmental fate of selected polybrominated diphenyl ethers in the region surrounding the Zhuoshui River of Taiwan based on an Equilibrium Constant fugacity model

Polybrominated diphenyl ethers (PBDEs) are a group of flame retardants that have been in use since the 1970s. They are included in the list of hazardous substances known as persistent organic pollutants (POPs) because they are extremely hazardous to the environment and human health. PBDEs have been extensively used in industry and manufacturing in Taiwan, thus its citizens are at high risk of exposure to these chemicals.
An assessment of the environmental fate of these compounds in the Zhuoshui river and Changhua County regions of western Taiwan, and also including the adjacent area of the Taiwan Strait, was conducted for three high risk congeners, BDE-47, -99 and -209, to obtain information regarding the partitioning, advection, transfer and long range transport potential of the PBDEs in order to identify the level of risk posed by the pollutants in this region.
The results indicate that large amounts of PBDEs presently reside in all model compartments – air, soil, water, and sediment – with particularly high levels found in air and especially in sediment. The high levels found in sediment, particularly for BDE-209, are significant, since there is the threat of these pollutants entering the food chain, either directly through benthic feeding, or through resuspension and subsequent feeding in the pelagic region of the water column which is a distinct possibility in the strong currents found within the Taiwan Strait. Another important result is that a substantial portion of emissions leave the model domain directly through advection, particularly for BDE-47 (58%) and BDE-209 (75%), thus posing a risk to adjacent communities.
Model results were generally in reasonable agreement with available measured concentrations. In air, model concentrations are in reasonably good agreement with available measured values. For both BDE-47 and -99, model concentrations are a factor of 2-3 higher and BDE-209 within the range of measured values. In soil, model results are somewhat less than measured values. In sediment, model results are at the high end of measured values.

Towards a budget approach to Pleistocene terraces: preliminary studies using the River Exe in South West England, UK

This paper presents a first approach to using a sediment budget methodology for paired terrace staircase sediments in SW England. Although a budget approach has become firmly established in Holocene fluvial studies, it has not been used in Pleistocene sequences due to the problems of temporal resolution, catchment changes and downstream loss from the system. However, this paper uses a budget approach in a paired non-glaciated basin, primarily as a method of interrogating the terrace record concerning the degree of reworking and new sediment input required to produce the reconstructed terrace sequences. In order to apply a budget approach a number of assumptions have to be made and these are justified in the paper. The results suggest that the Exe system can most parsimoniously be explained principally by the reworking of a Middle Pleistocene floodplain system with relatively little input of new resistant clasts required and a cascade-type model in geomorphological terms. Whilst this maybe partially a result of the specific geology of the catchment, it is likely to be representative of many Pleistocene terrace systems in NW Europe due to their litho-tectonic similarities. This cascade-type model of terrace formation has archaeological implications and sets the context for the Palaeolithic terrace record in the UK. Future work will involve the testing of this and similar budget models using a combination of landscape modelling and chronometric dating. ?? 2009 The Geologists' Association.

Pathways of recent fine-grained sediment transport on the central Portuguese continental margin

Com o intuito de estudar as principais vias de transporte de sedimentos finos recentes na zona central da margem continental Oeste Portuguesa, parâmetros geoquímicos, mineralógicos e granulométricos foram analisados em sedimentos superficiais e em matéria particulada colhida em armadilhas de sedimentos e integrados com observações da hidrodinâmica de fundo. Os parâmetros geoquímicos foram também estudados na coluna de sedimentos depositada nos últimos 150 anos e em sedimentos pré-industriais. Os referidos parâmetros determinados foram: concentrações elementares, isótopos estáveis de Pb, teores em materiais litogénicos, carbonato de cálcio e carbono orgânico. Os canhões de Lisboa-Setúbal e Cascais tiveram especial destaque no presente estudo dado que, até à data, encontram-se menos estudados que o Canhão da Nazaré. Os resultados mostram que a distribuição de sedimentos na zona central da margem ocidental Portuguesa é particionada pelos canhões e que a exportação de sedimentos da plataforma para zonas mais profundas da margem é restringida pelas correntes do talude, excepto onde os canhões funcionam como corredores para o transporte de sedimentos. Enquanto no Canhão de Lisboa-Setúbal, e provavelmente no Canhão de Cascais, o transporte de sedimentos até à zona inferior é limitada, provavelmente apenas despoletado por eventos de elevada energia, no Canhão da Nazaré o transporte ao longo do todo o canhão parece eficiente. As zonas superiores dos canhões de Lisboa-Setúbal e Cascais presentemente actuam como armadilhas de sedimentos finos, aprisionando partículas em suspensão provenientes da plataforma adjacente. A introdução directa de sedimentos provenientes das plumas dos rios Tejo e Sado nas zonas superiores dos canhões parece limitada, contudo a resuspensão dos sedimentos do prodelta do Tejo como resultado de ondas de tempestade e ondas de maré interna permite o transporte de sedimentos para os canhões adjacentes. Na plataforma de Lisboa-Setúbal-Sines foram identificadas as assinaturas geoquímicas e mineralógicas de diferentes fontes de sedimentos finos (e.g. estuários do Tejo e Sado, arribas costeiras, lagoas de St. André e Melides). As concentrações elementares pré-industriais são muito semelhantes nos canhões da Nazaré e Lisboa-Setúbal, mas variados graus de enriquecimento antrópico de metais traço estão presentes nos sedimentos recentes. A mais acentuada influência antrópica na última área referida é consistente com a sua proximidade a áreas densamente povoadas e industrializadas e com input de sedimentos originários dos rios Tejo e Sado, potenciais transportadores de partículas poluentes. A dispersão de Pb atmosférico parece também significativa sendo que toda a zona da plataforma continental adjacente aos canhões de Lisboa-Setúbal e Cascais apresenta-se enriquecida. A principal fonte de Pb antrópico identificada através de isótopos estáveis de Pb é consistente com a assinatura das cinzas de incineradoras. No Canhão de Lisboa a imersão de dragados contaminados parece ser também uma potencial importante fonte de metais traço antropogénicos.

Organic-walled dinoflagellate cysts in recent sediments from the Guadiana river estuary, South-East Portugal

Dissertação de Mestrado, Biologia Marinha, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2007

Abrasion, transport and distribution of sediment in selected streams of Southern Ontario and Western New York /

The rate of decrease in mean sediment size and weight per square metre along a 54 km reach of the Credit River was found to depend on variations in the channel geometry. The distribution of a specific sediment size consist of: (1) a transport zone; (2) an accumulation zone; and (3) a depletion zone. These zones shift downstream in response to downcurrent decreases in stream competence. Along a .285 km man-made pond, within the Credit River study area, the sediment is also characterized by downstream shifting accumulation zones for each finer clast size. The discharge required to initiate movement of 8 cm and 6 cm blocks in Cazenovia Creek is closely approximated by Baker and Ritter's equation. Incipient motion of blocks in Twenty Mile Creek is best predicted by Yalin's relation which is more efficient in deeper flows. The transport distance of blocks in both streams depends on channel roughness and geometry. Natural abrasion and distribution of clasts may depend on the size of the surrounding sediment and variations in flow competence. The cumulative percent weight loss with distance of laboratory abraded dolostone is defined by a power function. The decrease in weight of dolostone follows a negative exponential. In the abrasion mill, chipping causes the high initial weight loss of dolostone; crushing and grinding produce most of the subsequent weight loss. Clast size was found to have little effect on the abrasion of dolostone within the diameter range considered. Increasing the speed of the mill increased the initial amount of weight loss but decreased the rate of abrasion. The abrasion mill was found to produce more weight loss than stream action. The maximum percent weight loss determined from laboratory and field abrasion data is approximately 40 percent of the weight loss observed along the Credit River. Selective sorting of sediment explains the remaining percentage, not accounted for by abrasion.

Geology of the Gander Group, Gander River Ultramafic Belt and Davidsville Group in the Jonathan's Pond - Weir's Pond Area, northeast Newfoundland /

The study area is situated in NE Newfoundland between Gander Lake and the north coast and on the boundary between the Gander and Botwood tectonostratigraphic zones (Williams et al., 1974). The area is underlain by three NE trending units; the Gander Group, the Gander River Ultramafic Belt (the GRUB) and the Davidsville Group. The easternmost Gander Group consists of a thick, psammitic unit composed predominantly of psammitic schist and a thinner, mixed unit of semipelitic and pelitic schist with minor psammite. The mixed unit may stratigraphically overlie the psammitic unit or be a lateral facies equivalent of the latter. No fossils have been recovered from the Gander Group. The GRUB is a terrain of mafic and ultramafic plutonic rocks with minor pillow lava and plagiogranite. It is interpreted to be a dismembered ophiolite in thrust contact with the Gander Group. The westernmost Davidsville Group consists of a basal conglomerate, believed deposited unconformably upon the GRUB from which it was derived, and an upper unit of greywacke and slate, mostly of turbidite origin, with minor limestone and calcareous sandstone. The limestone, which lies near the base of the unit, contains Upper Llanvirn to Lower Llandeilo fossils. The Gander and Davidsville Groups display distinctly different sedimentological , structural and metamorphic histories. The Gander Group consists of quartz-rich, relatively mature sediment. It has suffered three pre-Llanvirn deformations, of which the main deformation, Dp produced a major, NE-N-facing recumbent anticline in the southern part of the study area. Middle greenschist conditions existed from D^ to D- with growth of metamorphic minerals during each dynamic and static phase. In contrast, the mineralogically immature Davidsville Group sediment contains abundant mafic and ultramafic detritus which is absent from the Gander Group. The Davidsville Group displays the effects of a single penetrative deformation with localized D_ and D_ features, all of which can be shown to postdate D_ in the Gander Group. Rotation of the flat Gander S- into a subvertical orientation near the contact with the GRUB and the Davidsville Group is believed to be a Davidsville D^ feature. Regional metamorphism in the Davidsville Group is lower greenschist with a single growth phase, MS . These sedimentological, structural and metamorphic differences between the Gander and Davidsville Groups persist even where the GRUB is absent and the two units are in contact, indicating that the tectonic histories of the Gander and Davidsville Groups are distinctly different. Structural features in the GRUB, locally the result of multiple deformations, may be the result of Gander and/or Davidsville deformations. Metamorphism is in the greenschist facies. Geochemical analyses of the pillow lava suggest that these rocks were formed in a back-arc basin. Mafic intrusives in the Gander Group appear to be the result of magraatism separate from that producing the pillow lava. The Gander Group is interpreted to be a continental rise prism deposited on the eastern margin of the Late Precambrian-Lower Paleozoic lapetus Ocean. The GRUB, oceanic crust possibly formed in a marginal basin to the west, is believed to have been thrust eastward over the Gander Group, deforming the latter, during the pre-Llanvirnian, possibly Precambrian, Ganderian Orogeny. The Middle Ordovician and younger Davidsville Group was derived from, and deposited unconformably on, this deformed terrain. Deformation of the Davidsville Group occurred during the Middle Devonian Acadian Orogeny.

Sediment genotoxicity and its relationship to the frequency of chironomid labial plate deformities

Sediment samples were taken from seven locations in the WeIland River in December 1986 and April 1987. The DMSO extracts of these sediment samples showed a significant (psediments from this l ocation. Analysis of sediment samples from the nearby station D-2 resulted in a significant (p <0 . 05) positive genotoxic response in December but not in April. Chironomids (midge larvae) taken from each of seven study locations were analyzed for the frequency of chironomid labial plate deformities (over 1000 individual specimens were observed) . The samples from station D-l showed the highest frequency of chironomid labial plate deformities (10 . 9% ± 3.2%), while samples from the upstream control (station A) displayed t,he lowest frequency of deformities (3.8% ± 1.3%). All samples were coded to avoid unconscious biases . The results of the genotoxicity study indicated that station D-l in the WeIland River was contaminated with genotoxic materials. The genotoxic materials may have induced the observed increased frequency in chironomid labial plate deformities . Samples from stations C and D-l, located in a downstream portion of the river bounded by an industrialized area were slightly toxic according to -the alkaline phosphatase inhib_ii~ion component of the 50S chromotest analyses. The toxicity of these samples was only evident once they had been activated by the 59 (liver extract) mixture.

Seasonal ramification in the biochemical composition of organic matter in Chalakudy river-estuary

The present study which is the first of its kind in this region is an attempt to generate adequate information on the relative abundances, the seasonal and spatial variations as well as on the source and fate of organic compounds found associated with the dissolved, particulate and sedimentary compartments of Chalakudy river system. The study aimed at investigating variations, the relative proportion of dissolved, particulate and sedimentary fractions of these materials as well as the pollution extent so as to be able to comment on the present condition of this river-estuarine system. This thesis focuses attention on the role of biogeoorganics in modifying the ecological and environmental condition of the dissolved, particuIate and sediment compartments with their minute variability subjected to various physical, chemical and biogeochemical processes. A scheme of study encompassing all these objectives provides the frame work for the present investigation.

Seasonality of modern pollen and sediment deposition in an estuarine context: the Severn Estuary Levels, southwest England

Recent sedimentological and palynological research on subfossil Holocene banded sediments from the Severn Estuary Levels suggested seasonality of deposition, registered by variations in mineral grain-size and pollen assemblages between different parts of the bands. Here we provide data that strengthen this interpretation from sampling of modern sediments and pollen deposition on an active mudflat and saltmarsh on the margin of the Severn Estuary, and comparison with a vegetation survey and contemporary records of climate, river and tidal regimes. The results of grain-size analysis indicate deposition of comparatively coarse-grained silts during the relatively cool and windy conditions of winter and comparatively fine-grained sediments during relatively warm and calm summer months. Pollen analysis demonstrates the significance of long-term storage of pollen grains and fern spores in the estuarine waterbody, superimposed on which seasonal variations in pollen inputs from local and regional vegetation remain detectable. Copyright (C) 2007 John Wiley & Sons, Ltd.

Interpreting the response of a dryland river system to Late Quaternary climate change

A U-series calcrete chronology has been constructed for three Late Quaternary terrace units, termed the D1, D2 and D3 terraces in age descending order, from the Rio Aguas river system of the Sorbas basin, southeast Spain. The D1 terrace formed between 30,300 +/- 4400 year BP and 12,140 +/- 360 year BP, correlating well with the Last Glacial Maximum when rates of sediment supply would have increased greatly, because of higher rates of weathering, reduced vegetation cover and weak soil development. The D2 terrace formed between 12,800 +/- 1100 year BP and 9,600 +/- 530 year BP, correlating well with the Younger Dryas event. The D3 terrace could only be poorly constrained to the early Holocene and no unequivocal cause could be assigned to this period of aggradation. The sedimentology and geomorphology of the D2 terrace suggests, however, that the aggradation of this unit was a response to diapirism/karstic processes occurring within the underlying Messinian gypsum strata and the subsequent damming of the Aguas system. Therefore, despite its coincident occurrence with the Younger Dryas, aggradation of the D2 terrace is unrelated to climate change. The style of this response, controlled predominantly by the characteristics of the underlying bedrock, makes correlating the terrace record of the Aguas with other systems in the Mediterranean unreliable. This study, therefore, highlights the problems of correlating fluvial sequences in regions of variable tectonics, climatic history and bedrock geology and emphasises the need to properly understand the main controls on individual fluvial systems before any attempt is made to correlate their depositional histories. (C) 2004 Elsevier Ltd. All rights reserved.

Distribution of selected heavy metals in sediments of the Agueda river (Central Portugal)

The state of river water deterioration in the Agueda hydrographic basin, mostly in the western part, partly reflects the high rate of housing and industrial development in this area in recent years. The streams have acted as a sink for organic and inorganic loads from several origins: domestic and industrial sewage and agricultural waste. The contents of the heavy metals Cr, Cd, Ni, Cu, Pb, and Zn were studied by sequential chemical extraction of the principal geochemical phases of streambed sediments, in the <63 mum fraction, in order to assess their potential availability to the environment, investigating, the metal concentrations, assemblages, and trends. The granulometric and mineralogical characteristics of this sediment fraction were also studied. This study revealed clear pollution by Cr, Cd, Ni, Cu, Zn, and Pb, as a result from both natural and anthropogenic origins. The chemical transport of metals appears to be essentially by the following geochemical phases, in decreasing order of significance: (exchangeable + carbonates) much greater than (organics) much greater than (Mn and Fe oxides and hydroxides). The (exchangeable + carbonate) phase plays an important part in the fixation of Cu, Ni, Zn, and Cd. The organic phase is important in the fixation of Cr, Pb, and also Cu and Ni. Analyzing the metal contents in the residual fraction, we conclude that Zn and Cd are the most mobile, and Cr and Pb are less mobile than Cu and Ni. The proximity of the pollutant sources and the timing of the influx of contaminated material control the distribution of the contaminant-related sediments locally and on the network scale.

Physico-chemical controls on phosphorus cycling in two lowland streams. Part 2 - The sediment phase

This article investigates the temporal and spatial controls on sediment-phosphorus (P) dynamics in two contrasting sub-catchments of the River Kennet, England. Suspended sediment (collected under representative flow conditions) and size-fractionated bedload (collected weekly for one year) from the Rivers Lambourn and Enborne was analysed for a range of physico-chemical determinands. Total P concentrations were highest in the most mobile fractions of sediment: suspended sediment, fine silt and clay and organic matter (mean concentrations of 1758, 1548 and 1440 mug P g(-1) dry sediment, respectively). Correlation analysis showed significant relationships between total P and total iron (n = 110), total manganese (n = 110), organic matter (n = 110) and specific surface area (n = 28) in the Lambourn (r(2) 0.71, 0.68, 0.62 and 0.52, respectively) and between total P and total iron (n = 110), total manganese (n = 110) and organic matter (n = 110) in the Enborne (r(2) 0.74, 0.85 and 0.68, respectively). These data highlight the importance of metal oxyhydroxide adsorption of P on fine particulates and organic matter. However, high total P concentrations in the granule gravel and coarse sand size fraction during the summer period (mean concentration 228 mug P g(-1) dry sediment) also highlight the role of calcite co-precipitation on P dynamics in the Lambourn. P to cation ratios in Lambourn sediment indicated that fine silt and clay and granule gravel and coarse sand size fractions were potential sources of P release to the water column during specific periods of the summer and autumn. In the Enborne, however, only the granule gravel and coarse sand size fraction had high ratios and a slow, constant release of P was observed. In addition, scanning electron microscopy work confirmed the association of P with calcite in the Lambourn and P with iron on clay particles in the Enborne. The study highlighted the importance of the chemical and physical properties of the sediment in influencing the mechanisms controlling P storage and release within river channels. (C) 2004 Elsevier B.V. All rights reserved.

Fine sediment delivery and transfer in lowland catchments: modelling suspended sediment concentrations in response to hydrological forcing

Fine sediment delivery to and storage in stream channel reaches can disrupt aquatic habitats, impact river hydromorphology, and transfer adsorbed nutrients and pollutants from catchment slopes to the fluvial system. This paper presents a modelling toot for simulating the time-dependent response of the fine sediment system in catchments, using an integrated approach that incorporates both land phase and in-stream processes of sediment generation, storage and transfer. The performance of the model is demonstrated by applying it to simulate in-stream suspended sediment concentrations in two lowland catchments in southern England, the Enborne and the Lambourn, which exhibit contrasting hydrological and sediment responses due to differences in substrate permeability. The sediment model performs well in the Enborne catchment, where direct runoff events are frequent and peak suspended sediment concentrations can exceed 600 mg l(-1). The general trends in the in-stream concentrations in the Lambourn catchment are also reproduced by the model, although the observed concentrations are low (rarely exceeding 50 mg l(-1)) and the background variability in the concentrations is not fully characterized by the model. Direct runoff events are rare in this highly permeable catchment, resulting in a weak coupling between the sediment delivery system and the catchment hydrology. The generic performance of the model is also assessed using a generalized sensitivity analysis based on the parameter bounds identified in the catchment applications. Results indicate that the hydrological parameters contributing to the sediment response include those controlling (1) the partitioning of runoff between surface and soil zone flows and (2) the fractional loss of direct runoff volume prior to channel delivery. The principal sediment processes controlling model behaviour in the simulations are the transport capacity of direct runoff and the in-stream generation, storage and release of the fine sediment fraction. The in-stream processes appear to be important in maintaining the suspended sediment concentrations during low flows in the River Enborne and throughout much of the year in the River Lambourn. Copyright (c) 2007 John Wiley & Sons, Ltd.

Eutrophication control in river-systems: an application of INCA-P to the River Lugg

The Integrated Catchments model of Phosphorus dynamics (INCA-P) was applied to the River Lugg to determine the key factors controlling delivery of phosphorus to the main channel and to quantify the relative contribution of diffuse and point sources to the in-stream phosphorus (P) load under varying hydrological conditions. The model is able to simulate the seasonal variations and inter-annual variations in the in-stream total-phosphorus concentrations. However, difficulties in simulating diffuse inputs arise due to equifinality in the model structure and parameters. The River Lugg is split into upper and lower reaches. The upper reaches are dominated by grassland and woodland, so the patterns in the stream-water total-phosphorus concentrations are typical of diffuse source inputs; application of the model leads to estimates of the relative contribution to the in-stream P load from diffuse and point sources as 9:1. In the lower reaches, which are more intensively cultivated and urbanised, the stream-water total-phosphorus concentration dynamics are influenced more by point-sources; the simulated relative diffuse/point contribution to the in-stream P load is 1: 1. The model set-up and simulations are used to identify the key source-areas of P in the catchment, the P contribution of the Lugg to the River Wye during years with contrasting precipitation inputs, and the uptake and release of P from within-reach sediment. In addition, model scenarios are run to identify the impacts of likely P reductions at sewage treatment works on the in-stream soluble-reactive P concentrations and the suitability of this as a management option is assessed for reducing eutrophication.

The sediment trapping efficiency of the macro-tidal Daly Estuary, tropical Australia

Field studies were carried out on the water and sediment dynamics in the tropical, macro-tidal, Daly Estuary. The estuary is shallow, very-turbid, about 100 km long, and the entrance is funnel-shape. In the wet, high flow season, normal tidal ranges can be suppressed in the estuary, depending on inflow rates, and freshwater becomes dominant up to the mouth. At that time a fraction of the fine sediment load is exported offshore as a bottom-tagging nepheloid layer after the sediment falls out of suspension of the thin, near-surface, river plume. The remaining fraction and the riverine coarse sediment form a large sediment bar 10 km long, up to 6 m in height and extending across the whole width of the channel near the mouth. This bar, as well as shoals in the estuary, partially pond the mid- to upper-estuary. This bar builds up from the deposition of riverine sediment during a wet season with high runoff and can raise mean water level by up to 2 m in the upper estuary in the low flow season. This ponding effect takes about three successive dry years to disappear by the sediment forming the bar being redistributed all over the estuary by tidal pumping of fine and coarse sediment in the dry season, which is the low flow season. The swift reversal of the tidal currents from ebb to flood results in macro-turbulence that lasts about 20 min. Bed load transport is preferentially landward and occurs only for water currents greater than 0.6 m s(-1). This high value of the threshold velocity suggests that the sand may be cemented by the mud. The Daly Estuary thus is a leaky sediment trap with an efficiency varying both seasonally and inter-annually. (c) 2006 Elsevier Ltd. All rights reserved.