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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Siktning som saneringsmetod för metallförorenad mark / Sieving as a decontamination method for metal contaminated soil

Riström, Emilia January 2015 (has links)
Toxic metals contaminate soil worldwide and thus serve as sever environmental threat. Therefore the purposes of this study were to investigate in which soil fractions that different heavy metals (Fe, As, Cu, Zn and Pb) could be found in contaminated soils and if it is possible to use sieving as a method for decontamination. Soil samples were collected from three different locations, the Nasa silver mine, the Blaiken-mine and Svalget environmental station. The samples were oven dried and later on sieved into six different fractions 8mm, 4 mm, 0.5 mm, 0.250mm, 0.063 mm and <0.063 mm. The fractions 4 mm, 0.5 mm and <0.063 mm from each location were analyzed in an x-ray fluorescence detector. The results showed that in general the smallest fractions contained the highest concentration of heavy metals which was very clear for Pb where 5 out of 6 samples had the highest concentration in the smallest fraction. The highest concentration of Cu (1147 ppm) and Zn (1117 ppm) were found in the smallest fraction in samples from the location Svalget. The highest concentration of Pb (10042 ppm) was also found in the smallest fraction in samples from Blaiken. In similarity the highest concentration of As (13305 ppm) was found in the smallest fraction in samples from the Nasa mine. However, in most samples the difference between the smallest fractions and the coarser material was small. Sieving may therefore not be the best way to decontaminate soil because even the larger fractions contained high concentrations of heavy metals.
112

Metal extractability and barley seedling metal accumulation from four municipal sewage sludges

Budzynski, James William January 1980 (has links)
No description available.
113

Εκτίμηση των περιβαλλοντικών συνθηκών στο Ν. Χαλκιδικής όσον αφορά τα βαρέα μέταλλα

Καταφιώτη, Μαλαματή 25 July 2008 (has links)
Σκοπός της παρούσας εργασίας είναι η εκτίμηση των περιβαλλοντικών συνθηκών στο Νομό Χαλκιδικής όσον αφορά τα Βαρέα Μέταλλα. Αυξημένες συγκεντρώσεις βαρέων μετάλλων εντοπίζονται ΒΑ του Νομού Χαλκιδικής λόγω της μεταλλευτικής δραστηριότητας. Η ποιότητα του περιβάλλοντος καθορίζεται από την γεωχημεία της περιοχής (λόγω της θειούχου μεταλλοφορίας) και από τον τρόπο που ασκήθηκε η μακρόχρονη δραστηριότητα στο παρελθόν, με τις μεθόδους εξόρυξης και τη συσσώρευση μεταλλευτικών υλικών χωρίς κανένα μέτρο προστασίας. Επίσης, δυτικά του Νομού Χαλκιδικής σημειώνονται αυξημένες συγκεντρώσεις Αρσενικού λόγω του γεωθερμικού πεδίου. / The main purpose of the dissertation is the estimation of the environmental conditions in the prefecture of Halkidiki, regarding the heavy metals. In the North East area of Halkidiki there are observed increasing concentrations of heavy metals because of the high metal activity of the area. The quality of the environment is determined from the geochemistry of the area (because of the sulfur ore) and from the way that the metal activity is implemented in the area, with the excavation methods that took place in the mining and the concentration of metal materials without specific protection measures. Also, in the West area of Halkidiki it is observed that the limit of arsenic in the ground and in the surface and underground waters has been exceed because of the geothermic field.
114

Comparative sensitivity of the early life history stages of the Blue Crab, callinectes sapidus, to mercury exposure

O'Malley, Kristen Marie 12 1900 (has links)
No description available.
115

The effects of heavy metals on anaerobic biotransformation reactions

Kong, In-Chul 05 1900 (has links)
No description available.
116

Quantifying Spatial and Temporal Deposition of Atmospheric Pollutants in Runoff from Different Pavement Types

Murphy, Louise Una January 2015 (has links)
Urban development leads to increased impermeable landscapes that interrupt the hydrological cycle by creating an impermeable barrier to the natural infiltration of precipitation. Precipitate, unable to infiltrate, flows over impermeable surfaces as sheet runoff, carrying the pollutants from the land with it; thus comprising the quality of the stormwater. The runoff is redirected (frequently untreated) to nearby waterways altering their water quality and quantity, thereby, adversely affecting receiving aquatic ecosystems. Suspended solids and elevated heavy metal concentrations in stormwater are the leading causes of water quality degradation in urban waterways in New Zealand. It is widely reported that vehicles and metal roofs are a major direct source of the key pollutants (total suspended solids (TSS) and heavy metals) in stormwater runoff; however, the contribution of atmospheric deposition, as an indirect source, in stormwater runoff is rarely considered. This is principally due to the many uncertainties and challenges with measuring and managing these pollutants in stormwater runoff. Therefore, a monitoring programme into the dynamics controlling atmospherically derived pollutant build-up and wash-off from urban surfaces was conducted. In particular, this research focused on the spatial and temporal variability of Cu, Zn, Pb, and TSS deposition in different land-use areas; the influence of pavement type on atmospherically-deposited pollutant loads in stormwater; and the contribution of wet deposition and dry deposition to the total deposition loads. Impermeable concrete boards (≈ 1 m2) were deployed for 11 months in different land-use areas (industrial, residential and airside) in Christchurch, New Zealand, to capture spatially distributed atmospheric deposition loads in runoff over varying meteorological conditions. Mixed-effect regression models were developed to explain the influence of different meteorological characteristics on pollutant build-up and wash-off dynamics. Next, impermeable asphalt, permeable asphalt, impermeable concrete, and permeable concrete boards were deployed for two months in a residential land-use area to determine the influence of pavement composition and roughness on pollutant loads in stormwater. Finally, wet deposition samples were analysed in an industrial land-use area for 8 months to monitor the contribution of wet deposition to atmospherically-deposited pollutant loads. All samples were analysed for total and dissolved Cu, Zn, Pb, and TSS. Pavement type: Results showed that both impermeable and permeable concrete were efficient at retaining Cu and Zn. Bitumen leaching from the impermeable asphalt was a significant source of Zn to runoff. However, bitumen leaching from the permeable asphalt did not contain elevated Zn loads. Infiltrate from the permeable asphalt provided little/no removal of Cu and Zn. Impermeable asphalt provided greater retention of TSS and Pb over impermeable concrete because its rougher surface entrapped more particulates. TSS and Pb loads were the lowest from the permeable pavements due to the pavers filtering out particulates. Spatial variability: Results showed that all three land-use areas exhibited similar patterns of varying metal and TSS loads, indicating that atmospherically-deposited metals and TSS had a homogenous distribution within the Christchurch airshed. This suggested that the pollutants originated from a similar source and that the surrounding land-use was not an important factor in determining atmospheric pollutant loads to stormwater runoff. Although, higher pollutant loads were found for the industrial area, this was attributed to local topographic conditions rather than land-use activity. Temporal variability: Results illustrated the importance of antecedent dry days on pollutant build-up. Peak rainfall intensity and rain duration had a significant relationship with TSS and Pb wash-off; rain depth had a significant relationship with Cu and Zn wash-off. This suggested that the pollutant speciation phase plays an important role in surface wash-off. Rain intensity and duration influenced particulate pollutants, whereas, rain depth influenced dissolved pollutants. Additionally, mixed-effect models could predict approximately 53-69% of the variation in airborne pollutant loads in runoff. Deposition pathways: Wet deposition was an important contributor of dissolved Zn to stormwater runoff. However, dry deposition was the greatest source of total Cu, Zn, and Pb loads in stormwater runoff. This is principally due to the low annual rainfall in Christchurch limiting pollutant removal via wet deposition unlike dry deposition, which is continually occurring. Understanding the dynamics of airborne pollutant deposition and their contribution to stormwater pollution could help stormwater managers in strategic decision-making processes such as choice of location and installation of different treatment systems.
117

Copper-binding peptides of Mimulus guttatus

Salt, David Edward January 1989 (has links)
No description available.
118

The influence of prey-surface contamination on aquatic invertebrate predators with contrasting modes of feeding

Robinson, Karen Ann January 1998 (has links)
No description available.
119

The pollution history of two urban lakes in Coventry, UK

Charlesworth, Susanne Margaret January 1994 (has links)
Human society has influenced the environment for at least the last 15000 years but, since the Industrial Revolution, the resultant environmental impacts have been widely used in many studies for reconstructing this impact over medium timescales (tens to hundreds of years). Few long-term studies of hydrological change exist and sediments are useful as surrogates for direct monitoring since they are sensitive to change within the catchment. This study uses the properties of urban lake sediments in order to reconstruct environment pollution history. The two principal objectives of this study were the reconstruction of historical atmospheric, point source and diffuse heavy metal pollution in an urban environment and the evaluation of the lake-sediment record as a source of proxy hydrological data over the last 100-150 years. A paired lake-catchment study was undertaken by comparing the records contained in a closed and an open lake. The closed lake (Swanswell Pool) is situated in the centre of the city of Coventry where the main source of pollution is atmospheric. This site provides a contrast to an open basin (Wyken Pool) with a multi-source catchment in addition to atmospheric influx. Trends in urban lake sediment cores indicate increasing heavy metal concentrations upcore, with cultural enrichment factors for individual heavy metals of between 55.4 and 2.6. Storage of heavy metals in the catchment of the closed basin were significant, although it was found that up to 85% of the Zn and 90% of the Pb were actually stored in the lake sediments. Catchment sources contributed up to 5 times more than the atmosphere in the Wyken Slough catchment. Heavy metals budgets were calculated, and these showed that loadings of metals have increased by up to 7.5 times between 1850 and the present day. Sequential digestion of the lake sediments at both sites showed that the important fractions containing heavy metals were Fe and Mn oxides and organic matter. The heavy metals associated with these fractions could be remobilised with changing environmental conditions, but an analysis of contemporary water quality indicated that, at present, suitable Eh and pH conditions for remobilisation did not occur. It was concluded that these urban lakes do preserve the heavy metals record and can provide surrogate data on medium-term environmental change. However, the complex mixture of materials associated with urban sedimentation resulted in a lack of correlation between heavy metals and mineral magnetic properties in either lake, and in the catchment of Wyken Slough. Hence mineral magnetic properties of sediments in urban catchments do not appear to be a suitable surrogate for heavy metals analysis. Urban lakes appear to provide a much-neglected opportunity for palaeolimnological reconstruction over a period when little directly monitored data exists.
120

Development of an integrated approach to understanding, managing and designing strategies and recycled organics filtration treatment system to control regional heavy metal contamination of stormwater.

Seelsaen, Nida, Civil & Environmental Engineering, Faculty of Engineering, UNSW January 2007 (has links)
Urban stormwater runoff is recognised as a substantial source of heavy metal contamination, which adversely impacts on water quality of regional receiving waterways. Conventional treatment of urban runoff mostly involves a filtration system using sand to retain particulate matters. Sand provides limited sorption of dissolved metals and the inclusion of commercial sorbents to these treatment systems is not cost effective due to the concentration of dissolved metals in the runoff. Recycled organic materials are by-products or waste from industrial or agricultural operations, and could be alternative low cost sorbents for stormwater treatment systems. The use of recycled sorbents also provides added value to the waste materials and reduces landfill disposal. The research explores the application of compost, zeolite, ash, and recyclable waste in urban runoff treatment, especially for dissolved metal removal. The research combines the two aspects of experimental studies and management analysis to develop a holistic approach to heavy metal control in urban stormwater systems. Experimental results of batch sorption test show that compost is suitable for removing dissolve copper in stormwater treatment. The comparison of the different mixing ratios between compost and glass beads in column test evaluates the optimum mixing sorbent and performance over a long period for copper removal. Substance Flow Analysis (SFA) of copper has been performed in the Upper Parramatta River Catchment, Sydney to identify the sources of copper associated with runoff, effect of using waste material such as compost in urban stormwater treatment and the copper load in urban stormwater runoff. This case study shows the relationship between copper input, copper stock, sorbent type and urban stormwater quality control in the system boundary of the catchment. Different scenarios of source control are evaluated to control copper load from the different sources. Source control focusing on roads and vehicles is the most effective copper control strategy. The combination of source control and stormwater treatment reduces copper in stormwater and receiving water. The thesis applies the analysis from SFA and experimental results to derive both a regional system-wide solution with source control, and an improved design of stormwater treatment for heavy metal removal using recycled organics.

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