Sediments can act as both reservoir and source of legacy organic contaminants such as polychlorinated biphenyls (PCBs). Due to their chemical stability and ubiquity, these contaminants remain as model class of compounds in the field of sediment contamination. Whole sediment and organism concentrations have been often used as exposure metrics for ecological risk assessments. However, whole sediment concentrations often overestimate the potential for exposure to contaminants; while organism concentrations based on bioassay provide a better estimate of exposure, bioassays can also be labor intense, time consuming and expensive. Alternatively, accessiblity-based techniques such as Tenax extractions have been gaining ground, in the last few decades, as a rapid, reliable, and cost-effective approach to estimate exposure to organic contaminants from sediments. Tenax extractions measure the bioaccessible fraction of the contaminant that desorbes from sediment. Despite the simplicity, accuracy and robustness of the Tenax technique to estimate bioaccessibility of organic contaminants, there are still some remaining questions regarding the methodological standardization, and the applicability of the technique in sediments containing diverse carbonaceous sorbents associated adsorption/desorption of the contaminant. Therefore, the chapters of this dissertation were designed to address these questions. To this end, PCBs were chosen as a model compound class to represent a wide range of physicochemical properties of persistent organic contaminants, and because these compounds remain a worldwide legacy contamination problem. The dissertation goals were to: determine the best operational conditions for Tenax technique (Chapter 2); monitor the changes in bioaccessibility of field-collected sediments with different holding time conditions (Chapter 3); examine the effects of the type and quantity of organic carbon on bioaccessibility (Chapter 4); and evaluate the applicability of the Tenax technique to assess remediation success in contaminated marine sediments (Chapter 5). To address the methodological standardization of the Tenax technique, the operational parameters of solvent extract volume, Tenax sorption rate from water, and Tenax:OC (Tenax:Organic Carbon) ratios were investigated in Chapter 2. The highest efficiency of extraction of sorbed PCBs from Tenax resulted from using a 10 mL per each solvent wash during Tenax extraction procedure. For the Tenax sorption, it was found that 0.01 g of Tenax cleared PCB in 40 mL of water in 30 min, thus it would clear the water 48 times in 24 h. When this is extrapolated to the 0.5 of Tenax, typical amount used, it was found that the amount should clear the typical volume of water used on Tenax extraction about 2400 times. This represents unequivocal evidence that the Tenax resin would remove PCBs dissolved in the liquid phase (e.g., overlying or interstitial water) present in the sediment sample and be limited only by compound desorption and not by the Tenax sorption capacity. The results examining the impact of the relationship between the amount of Tenax required and the amount of organic carbon in the sediment extraction indicated that a minimum of 5:1 Tenax:OC ratio be used to conduct Tenax extractions. This will reduce (eliminate) the possibility of re-adsorption by the native OC in the sediment in competition with the Tenax. After ascertaining the best operational conditions for Tenax extractions, two additional methodological uncertainties, the effect of storage time after collection and the preservation method associated with the handling of collected sediment samples were investigated in Chapter 3. The effect of holding time and the preservation method on PCB concentrations from field-collected sediments was examined for a period of 196 d. All samples were held at 4 ºC in the dark and several holding times were chosen. The parameters to track the changes in PCB concentration in two sediments used three exposure metrics: exhaustive solvent extraction, tissue concentrations and Tenax extractions (Chapter 3). The results showed that the total exhaustive concentrations representing the whole sediment concentrations did not significantly change (ANOVA, p> 0.05) in either sediment over the course of 196 d. Similar results were also found for the total Tenax concentrations that represented the bioaccessible sediment concentrations, and for the total organism tissue concentrations representing exposure. The likely equilibrium of PCB in the sediment, their chemical stability of PCB and slow degradation can be underlined as the main factors leading to these results. The long time that legacy contaminants such as PCBs have been in contact with contaminated sites (e.g., Superfund sites) might have contributed to an equilibrium to be reached between the sediment particles and PCB molecules. The significance of this chapter is that sediments collected from PCB-contaminated sites can be stored longer than the 14 d as recommended by current standard protocols without disturbing the measures of bioavailability. The role of organic carbon composition within sediment on contaminant sorption was also investigated to ascertain the effects of type and quantity of OC from different origins on the bioaccessibility of PCBs in contaminated sediments (Chapter 4). Changes in PCB bioaccessibility in sediments amended at either 3 or 6% by dry weight with black carbon (BC), humic acid (HA) or sawdust (SD), showed that the lowest and highest PCB bioaccessibilities were observed in the BC and SD amendments, respectively. Specifically, the total amount of PCBs desorbed ranges from 3 to 27% for BC amendments, 12 to 55% for HA amendments and 16 to 80% for SD amendments. The results showed the influence of OC quantity on bioaccessibility having a much slower desorption of PCBs in 6% amendments compared to 3% amendments, and this finding was most evident in HA and BC amendments. The results also showed that the Tenax technique can be applied to tract the variation in type of carbon and quantity of OC in contaminated sediment to estimate exposure. Finally, the applicability of the Tenax technique as tool to assess the remediation success of PCB-contaminated marine sediments upon AC amendment at either 4.3 or 0.026% AC by dw was examined in Chapter 5. The results showed that bioaccessibility of PCBs was greatly reduced in sediment amended at the higher AC dose (4.3%); while, reduction was also observed even in the sediment amended at 0.026% AC. Furthermore, the results revealed that Tenax concentrations reflected the PCB reduction among AC amended sediments in the same direction as the PCB reduction in the organism bioaccumulation. Overall, this dissertation provides further evidence that the Tenax technique is a rapid, reliable, and cost-effective tool for estimating exposure to recalcitrant organic contaminants such as PCBs from contaminated sites. The applicability of the technique to estimate bioaccessible compound from both freshwater and marine aquatic sediments underline the robustness of the technique to widen its use among risk ecological assessor and researchers.

Weeks Bay, AL is a governmentally protected reserve near Mobile Bay, AL, while Old Tampa Bay, FL is an urbanized estuary, located along the western coast of Florida. Estuary health is important to local economies and the health of local marine life, with an emphasis on low levels of eutrophication. Sediment oxygen demand (SOD) is usually measured to qualify the environmental health of estuaries, but SOD is timeconsuming and expensive. Average acid volatile monosulfides (AVS) concentrations were found to accurately predict SOD variances. The Degree of Pyritization (DOP) is a measure of long-term sediment oxidation conditions, which indicates normal estuary state. Despite the urban land use practices of these two bays, the DOP of each bay is similar.

Plast har skapat förutsättningar för oss människor i årtionden på grund av dess breda användningsområde. Det har dock medfört att det förekommer mängder mikroplaster i omgivningen och det är idag ett miljöproblem som behöver åtgärdas. Det är en utmaning att klargöra mikroplasternas ursprung, däremot går det att konstatera att konstgräsplaner är en av de största källorna i Sverige och bedöms släppa ut flera ton mikroplaster. För att ta reda på hur mycket mikroplaster en konstgräsplan kan sprida med dagvatten görs olika provtagningar i bl.a. vatten- och sedimentmiljöer. Syftet med detta examensarbete var att belysa olika provtagningsmetoder som kan användas vid provtagning av mikroplaster från konstgräsplaner i vatten och sediment. Därefter ska resultaten kunna användas som underlag för att anpassa framtida provtagningar för mikroplaster. Följande tre mål sattes därför upp; identifiera olika provtagningsmetoder som är lämpliga för mikroplaster, jämföra dessa med varandra och föreslå lämpliga provtagningsmetoder för mikroplaster från konstgräsplaner i främst vatten. För en lyckad provtagning krävs en noggrann planering och förberedelse innan utförandet. Det innebär att en konceptuell modell bör tas fram över hur fotbollsplanen är utformad, var och när provtagning ska utföras och vilka parametrar som ska analyseras samt att det finns referenser för bakgrundshalter, se figur 3, sida 16. Information om provtagningsplatsen behöver sammanställas, exempelvis vilka plastmaterial som finns i konstgräsplanen samt vilka förväntade primära och sekundära mikroplaster som kan spridas från den undersökta platsen. I examensarbetet identifierades två provtagningsalternativ för att undersökamikroplaster i vattenprover: • Provtagning av vatten (aktiv provtagning) för analys av mikroplast • Provtagning med filter (passiv provtagning) där vatten med mikroplast filtreras. I detta fall kan mikroplasterna som har fångats upp av filtret analyseras. Rapporten behandlar även andra provtagningar - provtagning med pump, hämtare och huggare. Detta för att se vilka alternativ som finns vid vatten- och sedimentprovtagningar samt för att få en jämförelse mellan dessa provtagningar. Vid provtagningar saknas det idag en gemensam standard för hur provtagning ska planeras och genomföras, vilket troligtvis hade underlättat arbetet vid provtagningar. Framförallt då resultaten lättare hade kunnat tolkas och jämföras med varandra. Ett studiebesök gjordes vid Bergaviks IP i Kalmar för att utföra provtagning i tre brunnar och i en närliggande dagvattendamm dit yt- och dräneringsvattnet från konstgräsplanen avvattnas till. Provtagningen började med att dagvattenflödet och nederbördsmängden under de senaste dygnen innan mätningstillfället noterades. Samtliga provtagningstillfällen sker vid liknande väder- och flödesförhållanden. Vattenproverna skickades sedan på analys. Denna metod går att upprepa och efter några provtagningstillfällen kan ett medelvärde på innehåll av mikroplaster tas fram. Examensarbetets slutsats är att det är viktigt att undersöka hur och var provtagningen utförs. Både när det handlar om aktiv provtagning och passiv provtagning gäller det att ta prover tas vid flera tillfällen, beskriva nederbördsförhållandena innan provtagning, ta prover på samma ställe och samma djup för att lättare kunna identifiera mängden mikroplaster från ursprungskälla samt hur mycket som sedan sprids vidare. Anledningen till att det idag främst är aktiv- och passiv provtagning som används vid provtagning av mikroplaster från konstgräsplaner är att det finns kommersiellt tillgängliga analysmetoder som är beprövade tillsammans med dessa provtagningsmetoder. Ett förslag på framtida studier är att identifiera en gemensam standard för utförande av provtagningen. Det skulle underlätta utvärdering av mikroplasters spridning från konstgräsplaner om samma standard användes överallt. / Plastics have created the conditions for us people for decades because of its wide use. It has, however, resulted that there are amounts of microplastics in the environment and it is today an environmental problem that needs to be fixed. It is a challenge to clarify the origin of the microplastics, but it can be stated that artificial turf is one of the largest sources in Sweden and is expected to release several tonnes of microplastics. To find out how much microplastics an artificial turf can spread with stormwater, various samples are taken in eg. water and sediment environments. The purpose of this thesis was to present various sampling methods that can be used when sampling microplastics from artificial turf in water and sediment. Then, the results can be used as a basis for adapting future samples for microplastics in water and sediment. The following three goals were therefore set up; identify different sampling methods suitable for microplastics, compare these with each other and suggest appropriate sampling methods for microplastics from artificial turf in mainly water. For successful sampling, planning and preparation are required before the execution. This means that a concept model should be developed over how the soccer field is designed, where and when samplings should be performed, which parameters should be analyzed and that there are references for background contents, see figure 3, page 16. Information about the sampling location needs to be compiled, for example, which plastic materials are present in the artificial turf and which expected primary and secondary microplastics can be spread from the soccerfield. During this thesis, two sampling alternatives were identified to investigate microplastics in water samples: • Sampling of water (active sampling) for microplastic analysis • Sampling of filtrate (passive sampling) where microplastic is filtered. In this case, the microplastics that have been captured by the filter are analyzed. This thesis also deals with other samplings - sampling with pump, water-container and dredge. It is because to see which alternatives are available for water and sediment sampling and for obtaining a comparison between these samples. At sampling, there is currently no common standard for implementation, which would probably have facilitated the sampling work. Especially when the results were easier to compare with each other. A study visit was made at Bergavik's IP in Kalmar to perform sampling in three wells and in a nearby stormwater pond to drain the surface and drainage water from the artificial turf. The sampling began with the stormwater flow and the amount of rainfall during the previous days before the measurement was noted. All sampling occasions occur at similar weather and flow conditions. The water samples were then sent for analysis. This method can be repeated and after a few sampling occasions, a mean value of microplastic content can be obtained. The thesis conclusion is that it is important to look at how and where the sampling is performed. Both when it comes to active sampling and passive sampling, it is necessary to take samples taken on several occasions, describe the precipitation conditions before sampling, take samples at the same place and the same depth in order to more easily identify the amount of microplastics from the source and how much is then disseminated. The reason why it is today mainly active and passive sampling that is used in sampling microplastics from artificial turf is that these are proven methods. A suggestion for future studies is to identify a common standard for execution. It would facilitate analyzes of microplastic spread from artificial turf if the same standard was used everywhere.

No description available.

No description available.

Hobble Creek is one of several inflowing streams and rivers into Utah Lake, Utah, USA. Historically, June sucker (Chasmistes liorus), a federally listed endemic fish, spawned up all the major inflowing streams and rivers but is now limited to just the Provo River. The State of Utah has recently proposed restoring the lower reaches of Hobble Creek for additional spawning and rearing needs. This restoration effort will likely involve removal of migration barriers, re-aligning the stream, and removing existing levees that prevent floodplain access. These changes have raised several questions that this study aims to answer. First, what are the sediment transport rates under current flow conditions in Hobble Creek, and how well do various predictive models match the actual rates? Secondly, assuming a successful introduction of adult June sucker into the Hobble Creek system, will the existing flow regime be capable of transporting the fry to an area adequate for successful population growth? Four bedload predictive models were used to create sediment rating curves for flows typically found in Hobble Creek: the Meyer-Peter, Muller equation (MPM), Wilcock's two parameter model, Rosgen's Pagosa reference curve, and Bathurst's Phase 2 equation. Each were used and compared to data obtained on Hobble Creek during the spring 2006 snowmelt runoff season. Results show that the uncalibrated MPM formula over predicted bedload rates by several orders of magnitude, while the Wilcock model sometimes performed more accurately, but was also prone to inaccuracies greater than an order of magnitude. The Rosgen and Bathurst predicted rates were consistently within an order of magnitude of observed rates. Areas of optimal rearing potential were determined by separating the stream-lake interface into four zones: dense vegetation, sparse vegetation, open lake, and within the creek. These four zones were analyzed for rearing potential based on food resources, temperature patterns and existing small fish densities. Larval drift modeling was performed to characterize the ability of the stream to transport larvae to the zones studied. We found that highest food density occurs in the open lake; small fish were most abundant in the open lake as well. The open lake is also better for rearing habitat in terms of temperatures between zones. Furthermore, larval drift studies show that the current geometry and flow regime is incapable of transporting larvae to zones in the lake where food and warm water are both available, and that larvae are likely to die before reaching those areas.

Lopez Lake Reservoir is the primary source of potable water for the Cities of Arroyo Grande, Grover Beach, Pismo Beach, and to the Community Service Districts of Oceano and Avila Beach. In this study, a water balance and sediment yield analysis model was developed for the reservoir’s watershed. The model was used to estimate evaporation from the lake and to examine the effects of a wildfire on the reservoir. Evaporation and wildfire are dependent on variables that change on a spatial and temporal scale, making modeling challenging. The County of San Luis Obispo uses pan coefficients to estimate evapotranspiration losses from the reservoir. In this study, a water balance model was developed using a watershed model known as Soil and Water Assessment Tool, SWAT. Evaporation loss from the lake was calculated using the inflows simulated by the model, and other fluxes (e.g., water released for consumption to Arroyo Grande Creek, precipitation) that were obtained from the County of San Luis Obispo. The evaporation values estimated by the pan coefficient model were significantly higher than the water balance and the Penman-Monteith predictions. The Penman-Monteith method estimates seem more reasonable for the lake. SWAT was also used to simulate effects of a wildfire on sediment inflow and sediment yield into the reservoir for a year after a simulated fire. Results showed that sediment inflow rates increased by a factor of 3 following the simulated wildfire. Lopez Lake Reservoir’s capacity would be significantly affected by a wildfire. To improve the evaporation estimates it is recommended that the County of San Luis Obispo install streamflow gauges to measure the inflow into the reservoir. Using the streamflow gauges the reservoir evaporation could be calculated using the water balance method. Adding climate gauges at the reservoir would increase the accuracy of the Penman-Monteith method. Sediment gauges in the watershed would provide a calibration data source for the model as well as data collection points in the event of an actual wildfire.

Yes / River dynamics and sediment transport play an important role in river bed morphology. Building a bridge pier along the river alters the cross-section of the river and causes the change in flow processes. These changes are mainly responsible for pier scour. In this paper, the usage of collars to reduce scour around circular piers has been investigated. The collars with different diameters and depth positions have been studied using previous data and additional data collected in the present study to assess their effectiveness in reducing scour. Using a wide range of measured data, an empirical equation to compute the maximum scour depth around the circular piers in the presence of collars has been proposed. The proposed equation has been validated and proven to be applicable to a wide range of pier layouts. It has been found that the maximum efficiency can be achieved by fixing the collar at bed level and adopting a collar diameter 1.5–2.5 times of pier diameter.

No / A discrete particle model is described which simulates bedload transport over a flat bed of a unimodal mixed-sized distribution of particles. Simple physical rules are applied to large numbers of discrete sediment grains moving within a unidirectional flow. The modelling assumptions and main algorithms of the bedload transport model are presented and discussed. Sediment particles are represented by smooth spheres, which move under the drag forces of a simulated fluid flow. Bedload mass-transport rates calculated by the model exhibit a low sensitivity to chosen model parameters. Comparisons of the calculated mass-transport rates with well-established empirical relationships are good, strongly suggesting that the discrete particle model has captured the essential elements of the system physics. This performance provides strong justification for future interrogation of the model to investigate details of the small-scale constituent processes which have hitherto been outside the reach of previous experimental and modelling investigations.

Lake Tuborg is a large lake on west-central Ellesmere Island, Nunavut. Part of the lake is meromictic, and contains trapped saltwater below about 55 m depth. The lake receives meltwater and sediments from multiple sources, including snowmelt and glacier melt. A lake process study was undertaken from 2001-2003 at Lake Tuborg that involved obtaining profiles of water temperature, salinity, transmissivity, and dissolved oxygen. Networks of short and long sediment cores were also obtained throughout the lake. During the last year of monitoring the lake and its sediments, a large catastrophic drainage of an ice-dammed lake occurred (a jökulhlaup). This was the largest jökulhlaup witnessed in Canada since 1947. Detailed measurements of lake conditions before, during, and after the jökulhlaup allowed the responses to be measured in great detail. The lake drained by floating its ice dam, an extremely rare drainage style in the Canadian High Arctic. The basin of Lake Tuborg closest to jökulhlaup inflow filled with fresh, cold and turbid water. A sill separates this basin from the larger more distal meromictic basin, and this sill effectively blocked turbidity currents from entering this basin. Conclusions from this phase of research include (1) salinity and temperature in the saltwater basin were minimally affected by the jökulhlaup, and (2) at a deep, distal location, an identifiable thick, coarse-grained, non-erosive deposit was produced by the jökulhlaup. The above conclusions allowed the varved sedimentary record to be examined for similar deposits in the past, with the assumption that similar deposits could be found in the long core record, the sediments could be dated, and that previous jökulhlaup deposits would also be nonerosive. Varve-thickness counting, Cesium-137 dating, and particle size analyses showed that prior to 1960, no similar events occurred in roughly the last thousand years. In addition, only three large jökulhlaups have occurred in the last thousand years, all of which occurred after about 1960. This significantly improves the understanding of the history of the lake, the surrounding glaciers, and the paleoclimate of the region. The lake bottom deposits that were sampled before, during and after the 2003 jökulhlaup were extraordinarily unique. A major part of the work of characterizing these deposits involved determining the size of their constituent particles. Image analysis of sedimentary particles using backscattered electron microscope imagery is a method to determine particle size at extremely high resolution. This tool improves on existing techniques since it automates the process of statistically processing images, quantifies the percentage of disturbances on images, and allows for extremely small measurement windows relative to particle size by implementing special particle counting rules.