An inverse Gaussian plume approach for estimating atmospheric pollutant emissions from multiple point sources

A method is developed for estimating the emission rates of contaminants into the atmosphere from multiple point sources using measurements of particulate material deposited at ground level. The approach is based on a Gaussian plume type solution for the advection-diffusion equation with ground-level deposition and given emission sources. This solution to the forward problem is incorporated into an inverse algorithm for estimating the emission rates by means of a linear least squares approach. The results are validated using measured deposition and meteorological data from a large lead-zinc smelting operation in Trail, British Columbia. The algorithm is demonstrated to be robust and capable of generating reasonably accurate estimates of total contaminant emissions over the relatively short distances of interest in this study

The behaviour of airborne particulates inside houses : its relevance to nuclear safety

In the context of the safety of nuclear installations, there is general concern over the release and dispersal of radioactive pollutants in particulate form into the atmosphere. Such a release may lead to radiation exposure to individuals under radioactive fall-out conditions in the form of direct gamma exposure, through inhalation or by the particulate material being deposited on internal and external surfaces of buildings. This project addresses the protection offered by buildings to the occupants, against such exposure pathways. A computer model (BHOUSE) has been developed to simulate the exchange and transport of pollution in aerosol form for a building. A particular aspect investigated, mainly through modelling, has been the protection afforded by buildings through the deposition indoors of aerosols which might infiltrate into the buildings in question. On the one hand this process is likely to reduce indoor air concentrations, thus reducing inhalation dose, on the other hand it may lead to the problem of long-term contamination inside buildings. A related consideration is the safety provided by the building, to the occupants inside, against the direct radiation emitted by the externally deposited activity. Various benchmarking exercises have been carried out to investigate the indoor air and contaminant dispersal. These exercises have included: pollution ingress rate to a building under a variety of conditions; effect of wet external deposition on mechanical transport rate; variation of indoor pollution level with and without vacuum cleaner operating and the calculation of inhalation dose rates. Measures to obtain higher protection factors against particulate inhalation have also been suggested. Predictions obtained with the model have been compared with an existing model. This comparison aimed to identify common features and significant differences between models. Such studies clearly relate to other non-nuclear aspects of indoor air quality research. A better understanding of the importance of individual parameters affecting indoor air quality has been achieved. The thesis also reports results obtained through participation in a joint experimental programme between Imperial College, the Danish Riso National Laboratory and the Building Research Establishment (BRE) which yielded measured indoor deposition velocities in an experimental terraced house using monodisperse aerosol labelled with a stable tracer. The deposition behaviour of particles with different sizes have also been studied. Neutron activation analysis was used to estimate aerosol concentration levels on air filters inside rooms, with the use of the Imperial College nuclear reactor. The resulting average deposition velocities were used in the model in order to illustrate the protection afforded by buildings against inhalation dose, for the aerosol sizes which were investigated. A critical review has also been conducted on aerosol test chamber studies

Hydrodynamics and Morphology in the Ems/Dollard Estuary: Review of Models, Measurements, Scientific Literature, and the Effects of Changing Conditions

The Ems estuary has constantly changed over the past centuries both from man-made and natural influences. On the time scale of thousands of years, sea level rise has created the estuary and dynamically changed its boundaries. More recently, storm surges created the Dollard sub-basin in the 14th -15th centuries. Beginning in the 16th century, diking and reclamation of land has greatly altered the surface area of the Ems estuary, particularly in the Dollard. These natural and anthropogenic changes to the surface area of the Ems altered the flow patterns of water, the tidal characteristics, and the patterns of sediment deposition and erosion. Since 1945, reclamation of land has halted and the borders of the Ems estuary have changed little. Sea level rise has continued, and over the past 40 years the rate of increase in mean high water (MHW) along the German coast has accelerated to 40 cm/ century. Climate has varied on a decadal time scale due to long-term variations in the North Atlantic Oscillation (NAO), which controls precipitation, temperature, and the direction and magnitude of winds. Between 1960 and 1990 the most intense variation in the NAO index on record was observed. As a result the magnitude and frequency of storm surges increased, and mean wave heights increased at 1-2 cm/year. Currently the NAO index—and therefore storminess—is trending downwards. Over the longer term, global warming models predict an average temperature rise of 2 degrees Celsius over the next century. A doubling of CO2 is expected to increase sea level by 30 cm, while the significant wind speed and wave heights in the North Sea are predicted to increase by 50 cm/s and 50 cm, respectively. Beginning in the late 1950’s, dredging activity and construction measures in harbours and shipping channels greatly altered the physical processes in the Ems. Deepening and streamlining the Ems River and shipping channel between the 1960s and 1990s decreased the hydraulic roughness and increased the tidal range in the river above Emden by as much as 1.5 m. At the turbidity maximum between Emden and Papenburg, concentrations of sediment are currently between 1-2 orders of magnitude larger than in the 1950’s, and fluid mud layers of several meters thickness occur. Other man-made changes, such as gas pipelines and the expansion of harbours, have often caused significant, but more localized, changes to the estuary. Between the mid 19th century and the 1970’s, dumping of organic waste—agricultural, industrial, and human—severely stressed the ecology of the Dollard sub-basin in particular. Since then the input of organic waste has been greatly reduced and anoxic conditions eliminated. However, the increase in turbidity at the turbidity maximum has caused depleted oxygen concentrations and periodic anoxia between Pogum and Papenburg during the summer months (personal communication, H. Juergens; Talke et al, 2005). The Ems is a relatively well studied estuary. Significant research projects have included the BOEDE project in the 1970’s --1980’s and the BOA and INTRAMUD projects in the 1990’s. These projects and other efforts have amassed a deep literature in the knowledge of tidal flats, fluid mud and flocculation, and mixing and dispersion processes. Projects currently underway are focusing on tidal dynamics and the affects of dredging in the high turbidity zone between Emden and Herbrum. Optimal management of the estuary is the goal of the HARBASINS project. Many analytical and numerical models have been applied to the Ems estuary to estimate tidal range, storm surges, wave fields, sediment transport, and mixing and dispersion processes. Analytical models to estimate mixing of scalars and sediment fluxes (Sediment Trend Analysis) have been extensively used. Numerical models such as WAQUA, unTRIM, MIKE3, Telemac 2D, SWAN, Delft 3D –Sed, and others have been applied to the Ems. While reasonable results are found for short term processes (order of days), long-term morphological change cannot yet be predicted. For the Ems catchement basin, the numerical models REGFLUD and FLUMAGIS are used to estimate nutrient inputs from diffuse sources and to visualize and evaluate the effects of land-use change

The significance of sedimentation and sediments to phytoplankton growth in drinking-water reservoirs

In the mesotrophic-eutrophic Saidenbach Reservoir in Saxony, the nanoplankton and cyanobacteria have increased at the expense of diatom dominance, due to a doubling of the external phosphorus load in the last 15 years. However, the phosphorus sedimentation flux is still very high (up to 80% of the input), corresponding to more than 2 g m2 d-1 in terms of dry weight. There is a strong correlation between the abundance of diatoms in the euphotic zone and their sedimentation flux (with a delay of about 2 weeks). Only about 25% of the deposited material could be clearly attributed to plankton biomass; the remainder resulted from flocculation and precipitation processes or directly from the inflow of clay minerals. The ash content of the deposited material was high (73%). Thus the sedimentation flux can be considered to operate as an internal water-treatment/oligotrophication process within the lake. The neighbouring Neunzehnhain Reservoir still has a very clear water with a transparency up to 18 m depth. Though the sediment was not much lower than Saidenbach sediment in total phosphorus and total numbers of bacteria, sulphide was always absent and the ratio of Fe 2+ to Fe 3+ was very low in the upper (0- 5 cm) layer. Thus the external and internal phosphorus loads do not attain the critical level necessary to induce a ”phosphorus - phytoplankton” feedback loop

Managing Dust on Unpaved Roads and Airports

INE/AUTC 14.1

Strength Regain of Clay Slurry using Additives

This report provides a comprehensive account of the data and observations gained from the research work carried out at the Department of Civil Engineering, Glasgow University on this 4-month contract funded by Technip UK Ltd from December 1st, 2009 to March 31st, 2010. The principal objective of the project was to determine by experiment which, if any, of a group of chemical additives were effective in accelerating the regain of strength of a marine clay following gross disturbance/remoulding by injection of water (and consequent increase in water content). The results of the test programme suggest that dosing with Calcium Hydroxide yields very promising results, and these results are presented at length. Other results are reported in the appendices and only briefly discussed herein.<p></p> Towards the end of the contract, further testing of the effect of the Calcium Hydroxide additive was undertaken at lower water contents than originally specified. In addition, some long-term tests (up to one year), which fall outside the scope of the contract, are currently being undertaken to establish whether the observed strength gain is permanent.<p></p&gt