No description available.

Community gardening in cities is increasing, driven by social interaction and food security. City soils are sinks for heavy metals; including neurotoxic lead (Pb). Exposure routes are primarily through inhalation/ingestion of soil, or second by ingestion of plants that have accumulated Pb. This research evaluates soil at three Liberty City, Florida sites estimating risk of Pb exposure through primary and secondary pathways. Soil cores were collected from Liberty City, and red Malabar spinach (Basella rubra) was grown in Pb soil treatments in a greenhouse. Total soil Pb levels and plant tissues were measured after acid digestion, by ICP-OES. In Liberty City, two sites had hotspots with areas of elevated soil Pb levels. Plants grown on Pb contaminated soil all accumulated statistically significant Pb concentrations. Therefore, there is a potential risk of Pb exposure to residents in Liberty City by exposure in hotspot sites through both the primary and secondary pathways.

A variety of world-class mineral deposits occur in Mesozoic and Tertiary rocks of the Guerrero terrane. New Pb isotope analyses of various crustal units and ores from distinct subterranes of the Guerrero terrane are presented to trace metal sources in these deposits and infer source reservoirs. New Sr and Nd isotope results are provided to gain insight into the provenance of the crustal rocks from the Guerrero terrane. Triassic schist samples from the Arteaga Complex and Triassic-Jurassic phyllite and slate samples from the Tejupilco metamorphic suite contain radiogenic Pb (206Pb/204Pb = 18.701-19.256) relative to bulk earth models. Cretaceous sedimentary rocks of the Zihuatanejo Sequence are more radiogenic (206Pb/204Pb = 18.763-19.437) than samples from the Huetamo Sequence (206Pb/204Pb = 18.630-18.998). Tertiary intrusive rocks from La Verde, Inguaran, La Esmeralda, and El Malacate plot to the right of the average Pb crust evolution curve of Stacey and Kramers (206Pb/204Pb = 18.705-19.033). Ores from the La Verde and La Esmeralda porphyry copper deposits yield isotopic ratios (206Pb/204Pb = 18.678-18.723) that are generally less radiogenic than the host igneous rocks, but plot within the field defined by the sedimentary rocks from the Huetamo Sequence. Tertiary intrusive rocks from the Zimapan and La Negra districts in the Sierra Madre terrane plot above and to the right of the Stacey-Kramers reference line (206Pb/204Pb = 18.804-18.972). Lead isotope ratios of ore minerals from the Zimapan and La Negra skarn mines (206Pb/204Pb = 18.775-18.975) resemble those of the associated igneous rocks, implying a magmatic Pb input in the skarn deposits. New Sr and Nd isotope data on metamorphic rocks (87Sr/86Sr = 0.707757-0.726494 and 143Nd/144Nd = 0.512109-0.512653) suggest that the basement of the Guerrero terrane originated from sources that had been derived from an old cratonic area. The narrow ranges and generally low 87Sr/86Sr ratios (0.704860-0.705755) and 143Nd/144Nd values (0.512765-0.512772) above that of bulk earth for igneous rocks from Inguaran, El Malacate, and La Esmeralda suggest a relatively low degree of crustal contamination. However, the isotopic values for the La Verde site (87Sr/86Sr = 0.708784 and 143Nd/144Nd = 0.512640) may indicate the involvement of a more evolved crustal component.

A detailed study, including the investigation of many methods of preparing a thallium sulphamate solution for thallium plating has been carried out. The optimum conditions for such a solution have been defined following experiments concerning the effect of different variables (polarisation, current density and additives). Satisfactory thallium electrodeposits have been obtained.

Twenty-one galena specimens from 16 mineral deposits in the Kootenay district analysed isotopically in replicate have a linear relationship of isotopic compositions on a Pb²º⁶/Pb²º⁴ versus Pb²º⁷/Pb²º⁴ graph. Twelve of the galenas, including two from Sullivan mine (East Kootenay district), were analysed by an intercomparison technique; the first application of the intercomparison method to an anomalous lead suite. Intercomparison results verify the linear compositional pattern (slope = 0.1084 ± 0.0033). These results indicate that: 1. Kootenay arc leads are multi-stage leads. 2. Sullivan-type lead is the parent common lead from which the anomalous suite developed. 3. Kootenay arc mineral deposits formed during one major mineralizing episode. Time of anomalous lead mineralization, tm, is probably Jurassic as deduced from potassium-argon dates and crosscutting relations of ores and igneous rocks. Assuming tm = 180 m.y. time of emplacement of uranium and thorium that produced the radiogenic component of the anomalous leads is approximately 1700 m.y., possibly the age of Lower Purcell strata of the East Kootenay district. Lead isotopic compositions show no obvious correlations with age of wallrock, type of wallrock, geological nature of ore deposits, or minor element content of galena. Post-ore thermal metamorphism and hydrothermal alteration do not appear to have changed lead isotopic compositions. The history of evolution of Kootenay arc anomalous leads is interpreted as follows: 1. Formation of source rocks containing uranium and thorium about 1700 m.y. ago. 2. Introduction of Sullivan-type lead into source rocks about 1340 m.y. ago. 3. Mixing of Sullivan-type lead with radiogenic lead formed by decay of uranium and thorium, and transportation and deposition of these "lead mixtures” to form anomalous lead deposits during Coast Range orogeny. Geologic and isotopic data from Sullivan mine are reconciled most easily with an epigenetic origin of the Sullivan orebody, and probably with a genetic relation of Sullivan ore fluids with the source magma of Moyie Intrusions. Holmes-Houtermans model age for Sullivan ore, based on intercomparison data, is 1340 m.y. Sullivan lead evolved in a source with U²³⁸/Pb²º⁴ = 9.02, Th²³²/Pb²º⁴ = 36.71, and Th/U = 4.07 (in terms of present day abundances). A method of estimating volume of source rock of anomalous lead deposits is outlined. Calculations for Jersey, Reeves Macdonald and Bluebell mines indicate that the radiogenic lead component of these deposits could have been derived from 1 to 10 cubic kilometers of source rock containing 3 ppm uranium (and approximately 12 ppm Th) if only one-third to one-half of the radiogenic lead in the source were extracted during a period of concentration and mineralization. Kootenay arc deposits can be divided into two classes on the basis of minor element contents of galenas. This division closely corresponds to the following geological types of deposits: 1. replacement deposits with no evidence of open space filling, and 2. deposits with evidence of open space filling and variable amounts of wallrock replacement. Minor element contents of galenas from Salmo-type replacement deposits suggest but do not prove a fairly low temperature of mineral deposition. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The turbidimetric method for the determination of lead ion developed in this work is not intended as a replacement for standard analytical procedures, but is presented solely as a laboratory exercise for courses in elementary instructional analysis.

The thesis is divided into several parts. At first, there are written information from the laws and decrees concerning the lead pipeline, drinking water, observance of lead concentrations in drinking water, etc. Then the water connection, the ownership relations to the connection and the materials used for the water connection are defined. The next chapter deals with lead, lead pipeline, lead in drinking water and the legislative requirements for lead content in drinking water. Other part is about the health risks of lead in drinking water. These theoretical parts follow the practical part, which focuses on drinking water quality testing, which was in contact with the lead pipeline. This section describes drinking water sampling principles for determining the concentration of lead, the locations where the samples were taken, the methods used to determine the concentration, the description, the results and the evaluation of the information. The last chapter shows the methods and materials that remove lead from water.

Although markets for alternative batteries, such as Li-ion, are growing, Pb-alloy batteries still dominate the market due to their low cost and good functionality. Even though these Pb-alloy batteries have been around since their discovery in 1859, little research involving advanced characterization techniques, such as synchrotron radiation X-ray diffraction (SR-XRD) and transmission electron diffraction (TEM) have been performed on Pb-alloys and sulfation, a failure mode in lead acid batteries, with regards to thermally- and electrochemically-induced changes at the atomic and microstructural scale. Therefore, there is a need to close this scientific gap between research and the application of Pb-alloy battery material. The main objectives of this research are to examine the process of sulfation and its growth mechanisms as well as to study the effects of minor alloying additions in Pb-alloy material. In the first case, nucleation and growth mechanisms of PbSO4 nano- and micro-particles in various solutions are examined using TEM to potentially reduce or control the buildup of PbSO4 on battery electrodes over time. The time dependency of particle morphology was observed using various reaction conditions. This insight can provide avenues to reduce unwanted buildup of PbSO4 on battery electrodes over time which can extend battery life and performance. This is followed by in situ SR-XRD studies of the grain growth and phase evolution associated with adding minor alloying elements, a varying combination of Sb, As, Ca, Sn, Al, In, Ba, and Bi, in Pb-alloy grid material during isothermal holds and thermal cycling. Additionally, sulfation studies were performed in H2SO4 solutions, and the Pb-alloys underwent cyclic voltammetry. Through this research, knowledge of elemental effects on Pb-alloys and corresponding sulfation effects provide insight into ways to extended the life and increase the efficiency of Pb-alloy batteries.

Water pollution due to heavy metals can be hazardous to both the environment and human health. The aim of this research is to provide a low-cost alternative for lead remediation. Biochar was produced from the fast pyrolysis of Douglas fir (DBC). Magnetic biochar (MDBC) was synthesized by mixing aqueous biochar suspensions with an aqueous Fe3+/Fe2+ solution. In chapter I, an overview of lead as an emergent contaminant is given. Different biochar production techniques have been discussed along with different mechanism of adsorption of lead onto biochar. Chapter II is a study of adsorption of lead on DBC and MDBC under different experimental conditions. The main aim of this research is to study the effect of water hardness on adsorption capacity. Three levels of water hardness were employed. Sorption performances were evaluated using Langmuir and Freundlich adsorption isotherms. DBC and MDBC were also successfully applied for lead removal from natural water samples. In chapter III, future projects focused on studying the effects of matrix chemicals found in natural waters on the heavy metal ion adsorption properties of biochar are discussed.

The city of Philadelphia is an amalgamation of extremely diverse land uses, both currently and historically, including: transportation, industrial, commercial, parks and residential areas. This urban tapestry of historical and current land use creates the potential for human exposure to heavy metals in contaminated soils. In order to evaluate this potential public health hazard, soil samples from open spaces in Philadelphia's Fairmount Park (the largest inner-city park system in the U.S.) were analyzed using a handheld x-ray fluorescence (XRF) analyzer and inductively coupled plasma-mass spectrometry (ICP-MS), focusing on Lead (Pb). Three distinct types of land use were identified for detailed analysis: undisturbed parkland, recently disturbed parkland and urbanized park/recreational land. At each location bulk and core samples were taken at specific geomorphic positions along a toposequence or, if little to no topographic change was present, samples were collected at specific intervals from structures or roads. These sites were compared to the geologic background Pb concentration (33 ppm). Less than 1% of samples analyzed were at or below the background Pb concentration for the region, suggesting anthropogenic input of Pb into the system. In total, 24 sites were sampled with three sites chosen for additional core and sequential extraction analysis. Selected samples were sequentially digested to determine Pb fractionation via ICP-MS. In most samples the Pb distribution was: Fe/Mn oxides > residuals > organic > carbonate > exchangeable fraction. Thus, most Pb was in less biologically available fractions. From the total Pb concentration data comparisons were made to a previously published model explaining Pb distributions in the urban environment, incorporating buildings to act as a baffle for aerosolized Pb particles, thus leading to increased Pb concentrations at the base of structures. By modifying this model and using a hill slope as the baffle, these data indicate that geomorphology can concentrate Pb at the bottom of hill slopes in a similar manner. Using the data collected in this study, we can develop an improved sampling model to characterize the potential public health risk associated with these three types of land use in Fairmount Park. This same approach can be used on public lands throughout the Philadelphia region in order to better assess the potential public health hazard posed by Pb and other toxic metals. / Geology