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1
Edvantoro, Bagus Bina. "Bioavailability, toxicity and microbial volatilisation of arsenic in soils from cattle dip sites". Title page, Contents and Abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09A/09ae24.pdf.
Testo completo
2
Stevens, Brooke Nan. "Bioaccessibility, Bioavailability, and Chemical Speciation of Arsenic in Contaminated Soils and Solid Wastes". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469101685.
Testo completo
3
Savoie, Courtney Beth Young. "Arsenic Mobility and Compositional Variability in High-Silica Ash Flow Tuffs". PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1012.
Testo completoAbstract (sommario):
Volcanic rocks typically have only low to moderate arsenic concentrations, none-the-less, elevated levels of arsenic in ground waters have been associated with pyroclastic and volcaniclastic rocks and sediments in many parts of the world. The potential for arsenic leaching from these deposits is particularly problematic as they often comprise important water-bearing units in volcanic terrains. However, the role that chemical and mineralogical variations play in controlling the occurrence and mobility of arsenic from pyroclastic rocks is largely unexplored.
This study uses chemical and X-ray diffraction data to characterize and classify 49 samples of ash-flow tuffs, and 11 samples of tuffaceous sediments. The samples exhibit a range of devitrification and chemical weathering. Total and partial digestion, and water extractions of samples are used to determine the total, environmentally available, and readily leachable fractions of arsenic present in all tuff samples. Leaching experiments were also performed with buffered solutions to determine the influence of elevated pH levels on arsenic mobility.
The 49 tuff samples have a mean arsenic content of 7.5 mg kg-1, a geometric mean arsenic content of 4.8 mg kg-1, a median arsenic content of 5.2 mg kg-1, and a maximum arsenic concentration of 81 mg kg-1. The mean and median values are 2.8 - 4.4x the average crustal abundance of 1.7 mg kg-1 (Wedepohl, 1995), and consistent with previously reported values for volcanic glasses and felsic volcanic rocks (Onishi and Sandell, 1955; Wedepohl, 1995), although the maximum arsenic content is higher than previously reported (e.g., Casentini et al., 2010; Fiantis et al., 2010; Nobel et al., 2004). In addition, the arsenic concentrations of tuffs were found to be highly heterogenous, both between and within individual units, and in some cases, individual outcrops.
Results of whole rock and leachate analyses indicate that there is no significant difference in the total arsenic content of tuffs as a result of devitrification or weathering, but both devitrified and weathered tuffs contain higher levels of environmentally available arsenic than unweathered glassy tuffs. Glassy tuffs did not produce any readily leachable arsenic, while individual devitrified and weathered tuffs both generated aqueous concentrations that exceeded regulatory limits after 18 hours. Leaching of weathered tuffs produced higher levels of arsenic at high (~9-11) pH than in tests conducted at circum-neutral pH. Devitrified and glassy tuffs showed no increase in leachable arsenic with increasing pH.
The results of this study indicate that devitrification and weathering processes determine the host phases, degree of adsorption, and overall mobility of arsenic from ash-flow tuffs. Tuffs that have undergone different types of alteration are likely to have different host phases of arsenic, and different mechanisms that mobilize arsenic into the environment. Potential host phases and mobility mechanisms are discussed, and a conceptual model of arsenic behavior in ash-flow tuffs is proposed.
4
Bauer, Elizabeth Nanette. "MODIFICATION OF AN EXISTING BENTHAL MODEL FOR PAPER MILL WASTES". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275443.
Testo completo
5
Tsai, Yi-Chang. "A quantitative spatial thoroughness methodology for environmental site characterization". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19503.
Testo completo
6
Woods, William Eric. "Copper migration through petroleum-treated soils". Virtual Press, 1990. http://liblink.bsu.edu/uhtbin/catkey/722463.
Testo completoAbstract (sommario):
The purpose of the project was to determine the effect of various petroleum amendments on the migration rate of Cu. The petroleum amendments used in this research are frequently added to the soil surface in petroleum landfarming. Such petroleum wastes often contain significant amounts of Cu and other metals.Soil columns were amended with citric acid, used crankcase oil and Illinois crude oil. Each amendment was spiked (treated) with three different concentrations of Cu and each treatment was replicated three times. The columns were leached once per week, for ten weeks, with distilled water acidified to pH 4.5 to simulate acid rain. Leachate from the soil columns was analyzed weekly for total Cu. At the end of the ten week period, the soil was analyzed for Cu and TOC content at 7 cm intervals to determine the amount of migration by Cu and the organic amendments, resectively. The soil (a Glynwood silt loam) and the organic amendments were each analyzed for total Cu to determine background levels. The soil was analyzed for pH, TOC, electrical conductivity and soil texture.Analysis of the leachate and soil showed differential migration of Cu through the soil columns. Significant levels of Cu leached in the columns amended with citric acid (as high as 85.3 mg/L) in the first 3 weeks of the study. The Cu content of the leachate from columns amended with crude petroleum were at approximately background levels (5.5 mg/L) as was the leachate from columns amended with crankcase oil (0.2 mg/L). In the later weeks of the research, as the petroleum amendments were broken down by microorganisms, some Cu was chelated to small fragments of the petroleum and leached through the soil columns. Most of the Cu appeared to remain on the surface of the columns, bound to the petroleum amendments. Analysis of the soil, for total Cu content with depth, showed very little Cu accumulation at any depth in the soil column, beyond the soil surface. In most cases Cu levels remained near the background levels found in the control columns.Moderate correlation was found (r2 = .59 for crude oil; r2 = - .54 for crankcase oil; r2 = .85 for citric acid) between Cu levels and TOC levels in the soil columns with depth.From the results of the current study it can be inferred that practices such as petroleum landfarming and land disposal of some hazardous materials may allow for the migration of both the applied petroleum wastes and any metals which may be contained within.Department of Natural Resources
7
Hung, Chien-ho. "Evaluation of leaching mechanisms and long-term leachability of metallic contaminants solidified/stabilized by cement matrices". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20761.
Testo completo
8
Swarna, Anitha. "Removal of Arsenic Using Iron Coated Limestone". TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1342.
Testo completoAbstract (sommario):
Arsenic contamination in drinking water is a severe problem worldwide. The best way to prevent hazardous diseases from chronic arsenic exposure is to remove the exposure. Efforts to remediate arsenic in drinking water have taken two tracks. One is to provide surface or shallow well water sources as an alternative to the arsenic contaminated deep wells. Another approach is to remove arsenic from the contaminated water. Different removal technologies like oxidation, chemical coagulation, precipitation, adsorption and others are available. There are problems and benefits associated with each of these approaches that can be related to cultural, socio-economic and engineering influences. The method proposed in this research is adsorption of arsenic to iron coated limestone. Different iron coated limestone samples were prepared. Standard solutions of 100ppb arsenic were prepared and batch and kinetic experiments were conducted. The final solution concentrations were analyzed by Graphite Furnace Atomic Adsorption Spectroscopy (GFAAs) and the results showed that iron coated limestone removed arsenic below 10ppb with 5 grams of material. Variations in iron coverage impacted efficiency of arsenic removal.
9
Lesley, Michael Patrick. "The fluxes and fates of arsenic, selenium, and antimony from coal fired power plants to rivers". Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180307/unrestricted/lesley%5fmichael%5fp%5f200312%5fms.pdf.
Testo completo
10
Yang, Yun. "Temperature dependent PCDD/PCDF product distributions from phenols". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20182.
Testo completo
11
Tlhapane, Keatlaretse Kefilwe. "A case study exploring the level of awareness of NCP Chlorchem's staff of environmental costs associated with hazardous waste". Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1015639.
Testo completoAbstract (sommario):
[Integrative executive summary] NCP Chlorchem (Pty) Ltd manufactures and distributes Chlor alkali products such as chlorine, hydrochloric acid, caustic soda flakes, etc. and in the process generates both hazardous and general waste. Following changes in South African waste management legislation in 2011, the organisation’s waste service provider had to increase the costs associated with the handling of site’s hazardous waste. Top management of NCP Chlorchem (Pty) Ltd requested a meeting with the waste service provider in order to establish the reasons behind the price increase. In that meeting, which the researcher attended, the waste service provider explained the changes in waste legislation and how it was going to impact on their business. Top management understood the reasons behind the price increase; however, they requested the waste service provider to review the price increase. The waste service provider gave the top management of NCP Chlorchem (Pty) Ltd assurance that they were going to discuss the price reduction request with their own senior management and would provide feedback. The researcher did not participate in the feedback meetings; however, to this day, NCP Chlorchem (Pty) Ltd still uses the services of the same waste service provider. The effect the escalating annual waste handling costs has had on NCP Chlorchem (Pty) Ltd’s management team led to the study. Environmental impacts have costs that directly impact on company’s bottom line, such as the costs associated with the generation of waste. Although environmental costs are only one of the many costs incurred by businesses, they deserve management’s attention. According to Jasch (2003), there is an apparent lack of awareness and understanding of the magnitude of the environmental costs generated by organisations, and many opportunities for cost savings through good environmental management are lost. However, using a relatively new tool in environmental management, that is, environmental management accounting (EMA), management would ensure that relevant and significant environmental costs are considered when making business decisions (Jasch, 2003). The main purpose of the thesis is to explore the level of awareness of environmental costs associated with hazardous waste within NCP Chlorchem (Pty) Ltd. In order to carry out the study, literature about environmental and cost accounting as well as literature on waste management was reviewed. Questionnaires were distributed to staff members, and meetings were held with different senior personnel. This case study seeks to answer the following questions: What is NCP Chlorchem (Pty) Ltd’s staff members’ level of understanding of waste management? What is the level of awareness of NCP Chlorchem (Pty) Ltd’s staff of environmental costs with regard to the generation, handling, transportation and disposal of hazardous waste? How can the current traditional accounting within the organisation be integrated with environmental management accounting? The findings of the first research objective revealed that staff members knew the site’s waste streams as per the South African legal definition of waste and as identified in the site’s environmental management system documentation. The conceptual approach to waste management is underpinned by the waste hierarchy. The respondents support the waste hierarchy in its approach to waste management, which is prevention of waste, reduction, reuse, recycle and safe disposal of waste as the last resort. Lack of awareness of environmental management, among other things, was cited as the cause of waste. In addition to that, the respondents believe the waste hierarchy can be achieved by employing recycling facilities, following procedures and by carrying out environmental awareness campaigns. Improving process design and control and including changes in raw material was cited, among other things, as the respondents’ perception on how waste can be reduced. The findings of the respondents’ understanding of waste hierarchy revealed that staff members understood waste management. The respondents cited the impacts of waste on the business as financial impact on the business, impact on their bonuses, and possible loss of business. In relation to the second research objective, it was found that staff members knew the hazardous waste streams and identified amongst other waste, sludge and chlorine emissions as NCP Chlorchem (Pty) Ltd’s hazardous waste. However, with regard to environmental management accounting data, an average of 55.1% of respondents were not familiar with the physical and monetary components of EMA. An average of 19.6% of respondents who were aware of EMA might have been senior personnel. It could further be established that those who were familiar with EMA information were actually working with the data, either for reporting purposes, or for employing waste minimisation strategies, as well as awareness purposes, to their juniors. On average, 80% of the respondents perceived the production department as the area within site that has the EMA information.
12
Lou, Laiqing. "Arsenic uptake, accumulation and tolerance in Chinese brake fern (Pteris vittata L., an arsenic hyperaccumulator) under the influence of phosphate". HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/928.
Testo completo
13
Baker, Scott Alan. "Activated sludge biotreatability of pulp and paper bleach wastes : investigation of bleaching options". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/21647.
Testo completo
14
Akki, Umesh. "Gas phase formation pathways and mechanisms of polychlorinated dibenzo-p-dioxins and dibenzofurans". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/23157.
Testo completo
15
Uddin, G. M. Saleh. "Groundwater contamination by arsenic in Bangladesh : causes, consequences and solutions". Title page, table of contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09ENV/09envu18.pdf.
Testo completo
16
Smith, Euan. "Chemistry of arsenic in soils of north-east New South Wales /". Adelaide, 1998. http://web4.library.adelaide.edu.au/theses/09ASOP/09asops646.pdf.
Testo completo
17
Vaughn, Michelle Lynn. "Internal dose assessment calculations for the proposed low-level radioactive waste disposal facility in the southeast compact". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/17378.
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18
Booker, Randall Sulter Jr. "Microbial reductive dechlorination of hexachloro-1,3-butadiene". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20921.
Testo completo
19
Leung, Ho Man Homan. "Interactions of arbuscular mycorrhizal fungi with an arsenic hyperaccumulator plant (pteris vittata) on the uptake of arsenic". HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/945.
Testo completo
20
Dodd, Matthew. "Arsenic speciation studies on some marine invertebrates of British Columbia". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28664.
Testo completoAbstract (sommario):
Graphite furnace and hydride generation atomic absorption, GFAA and HGAA, techniques have been developed and applied to the determination of arsenic concentrations in some marine invertebrates, mainly bivalves and gastropods, of British Columbia. Total arsenic concentrations in bivalves vary with species, ranging from 0.6-9.1 μg g⁻¹ (wet weight basis). Arsenic concentrations in the bivalve shells show a wider range of 0.1 to 26.3 μg g⁻¹ (dry weight basis). Gastropods show relatively higher arsenic concentrations in the soft tissues, 17.3-48.4 fig μg g⁻¹, and concentrations in the shells range from 1.4 to 16.3 fig μg g⁻¹. There is no correlation between arsenic levels in the soft-tissues and shells. There is also no correlation between arsenic levels in the organisms and the surrounding sediments and sediment pore waters.
HPLC-GFAA techniques have been developed and used for the separation and quantitation of-arsenite, arsenate, methylarsonic acid, dimethylar-sinic acid, arsenobetaine, arsenocholine iodide and tetramethylarsonium iodide. This technique together with TLC, NMR, FAB and thermospray LCMS were employed for the detection of water-soluble arsenic compounds in 5 species of clams - Butter clam Saxidomus giganteus. Horse clam Schizothoerus nuttalli. Soft-shelled clam Mva arenaria. Native-littleneck clam Protothaca staminea and Manila clam Venerupis laponica. Varying amounts of arsenobetaine and tetramethylarsonium ion are found in all the clams. Butter clams show the pres ence of a third compound which appears to be trimethylarsine oxide. Small amounts of unknown arsenic containing compounds are present which are yet to be characterized
.
Arsenic speciation in 3 gastropods was also examined. The Northwest neptune Neptunea lvrata. the Thick-ribbed whelk Berinpius crebriscotata and Phoenician whelk Neptunea phoenicius all contain arsenobetaine and at least two unidentified arsenicals.Science, Faculty of
Chemistry, Department of
Graduate
21
Smith, Euan. "Chemistry of arsenic in soils of north-east New South Wales / by Euan Smith". Thesis, Adelaide, 1998. http://hdl.handle.net/2440/22476.
Testo completoAbstract (sommario):
Bibliography: leaves 137-151.xiii, 151 leaves : ill. ; 30 cm.
Ten soils from northern New South Wales, Australia, were sampled and assessed for their capacity to sorb arsenate (Asv) in relation to soil properties.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1998
22
Robinson, Janet E. "Hazardous waste treatment and disposal: alternative technologies and groundwater impacts". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91066.
Testo completoAbstract (sommario):
The most important thermal, chemical, physical, and biological methods for treating hazardous wastes and the fate of their land-disposed residues are reviewed and evaluated. Technologies are described as major, minor, and emerging according to their stage of development or application to hazardous waste; major ones include rotary kiln, liquid injection, and cement kiln incineration; neutralization, chemical oxidation-reduction, and ion exchange; filtration, distillation and settling techniques; and activated sludge, aerated lagoon, and landfarming treatment. Emerging technologies include molten salt and fluidized- bed combustion, liquid-ion extraction and other processes, none of which are considered to be outside the realm of current or future economic feasibility. In addition, waste reduction strategies and the land burial of stabilized/solidified wastes are discussed. Residues from these technologies vary widely according to waste type and composition, but a common component in many of them is heavy metals, which, as elements, cannot be further degraded to other products. The results of the available literature suggests that these metals will be retained in clay liners beneath a landfill through the mechanism of cation exchange, with the adsorption of metals favored by their smaller hydrated size, lower heat of hydration, and in some cases, higher valences than the naturally occurring alkali earth metals. Other important factors include ionic activity, the pH and ionic strength of the solution, the presence of complexing agents, and the possible surface heterogeneity of the clay. In soils, metal binding through cation exchange with clay is augmented by adsorption onto iron and manganese oxides and complexing with organic matter such as humic acids. Many field studies with landfarmed metal-bearing wastes show that these mechanisms are usually sufficient to retain metals to within several inches of their zone of application.M.S.
23
Ricker, Tracy Ryan. "Arsenic in the Soils of Northwest Oregon". PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/927.
Testo completoAbstract (sommario):
One hundred and eighty-six soil samples from Northwest Oregon were tested for arsenic content. The highest values measured were 13.9 ppm in the A horizon (site C4) and 20.4 ppm in the B horizon (Site P4). Arsenic was not detected in 28 A horizon samples and 23 B horizon samples. Data are grouped based on the age and rock type of underlying bedrock. Lithologic groups with six or more data points were compared statistically to ascertain if groups are distinct. Analysis of Variance (ANOVA) multiple comparison tests indicate that the arsenic content of the Marine Sediments and Sedimentary Rocks group samples is distinguishable from the Quaternary Basalts group in the A horizon and all other groups in the B horizon. Kruskal-Wallis multiple comparison tests indicate that the arsenic content of the Marine Sediments and Sedimentary Rocks group is distinguishable from the Quaternary Basalts, Quaternary/ Tertiary Sediments and Sedimentary Rocks and Volcanic Sediments groups in both the A and B soil horizons. The ANOVA and Kruskal-Wallis tests compared A and B horizon data by lithologic group. The ANOVA shows the Marine Sediments and Sedimentary Rocks group in the A horizon is distinct from the Quaternary Basalts in the A and B horizon. The Kruskal-Wallis test yielded the same result. Per the ANOVA, the Marine Sediments and Sedimentary Rocks in the B horizon are distinct from all other tested groups. The Kruskal-Wallis test shows the Marine Sediments and Sedimentary Rocks group in the B horizon as distinct from the Quaternary Basalts, Quaternary/ Tertiary Sediments, and Volcanic Sediments groups in the A and B horizon. A K-means cluster analysis was used to group all available data independent of underlying bedrock. Three, four, and five group analyses were conducted, and the results of these tests were compared to the data grouped by underlying rock type. No correlation between the groups resulting from the K-means cluster analysis and groups based on underlying lithology was found. This analysis supports the creation of a map distinguishing arsenic content in the soils above Marine Sediments and Sedimentary Rocks group units from arsenic content in all other tested lithologic groups. The mean and standard deviations of these groups (in ppm) are: A horizon: Marine Sediments (6.09 ±2.66); other groups (3.10 ±3.19); B horizon: Marine Sediments (10.26 ±4.65); other groups (3.13, ±2.52). This analysis indicates that geologic context must be taken into account when determining background levels of naturally occurring arsenic in soils.
24
Sorenson, Mary T. "Deterministic vs probabilistic ecological risk assessment modeling at hazardous waste sites : a comparative case study". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/25303.
Testo completo
25
Mayer, Kate A. "Laboratory chamber experiments simulating in-situ plasma vitrification for geoenvironmental concerns". Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/18990.
Testo completo
26
Ng, Ting-leung Gordon, e 吳庭亮. "An assessment of strategies for the management of plastic bag wastes in Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31234392.
Testo completo
27
Wu, Chuan. "Effects of radial oxygen loss (ROL) on arsenic tolerance, uptake and distribution by rice (Oryza sativa L.)". HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1246.
Testo completo
28
Momplaisir, Georges-Marie. "Development of analytical methods for the speciation of arsenic in the marine environment". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40201.
Testo completoAbstract (sommario):
Several biologically important arsenic compounds including methylarsonate, trimethylarsine oxide, tetramethylarsonium ion, arsenobetaine and arsenocholine were prepared, in good yields, from sodium arsenite, or dimethylarsinic acid. These organoarsenic compounds together with arsenite, arsenate and dimethylarsinic acid were used as standards for the development of analytical methods for determining the levels of individual arsenic compounds (arsenic speciation) present in natural matrices.Arsenobetaine, arsenocholine and tetramethylarsonium ion were separated by high performance liquid chromatography (HPLC) with on-line detection by thermochemical hydride generation (THG)-AAS. The analytes were eluted from the cyanopropyl bonded phase HPLC column with a 1% acetic acid methanolic mobile phase which also contained diethyl ether triethylamine, and trimethylsulfonium iodide or picrylsulfonic acid. A surface response methodology and a univariate optimization procedure were used to determine the optimum concentration of solvent modifiers in the methanolic mobile phase. Limits of detection in the range 4-5 ng (as As) were obtained for the arsonium analytes under optimum chromatographic conditions.
A simple phenol extraction procedure was developed to isolate arsonium analytes from edible marine tissues (lobster tail muscle, peeled and deveined shrimp, and cod fillet), cod liver oil and human urine. The crude extracts were separated on the cyanopropyl column using a methanolic mobile phase and detected on-line by THG-AAS. Recoveries from tissues or from urine which had been spiked at 0.1-3.4 $ mu$g of As cation/g of fresh weight were 80% or greater for each of five sample types.
An improved HPLC-AAS interface which was compatible with either aqueous or organic mobile phases was also developed. The interface provided approximately equivalent responses to different arsenic oxidation states which resulted in low to subnanogram chromatographic limits of detection for arsenic oxyanions and arsonium cations in an aqueous or methanolic mobile phase. Nascent As anions and As cations were conveniently coextracted from aqueous solution or from fish muscle by phenol extraction and quantified in the same chromatographic run. This method has been applied to a standard reference sample of dogfish muscle (DORM-1), a marine reference sediment sample (PACS-1) and to sediment porewaters (SAG-15) from the Saguenay Fjord.
29
Assemi, Shoeleh 1963. "Use of flow field-flow fractionation for the characterisation of humic substances". Monash University, Dept. of Chemistry, 2000. http://arrow.monash.edu.au/hdl/1959.1/9028.
Testo completo
30
Hurtado, Heather Ann. "Naturally Occurring Background Levels of Arsenic in the Soils of Southwestern Oregon". PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2996.
Testo completoAbstract (sommario):
This study examines the natural background concentrations of arsenic in the soils of southwest Oregon, using new samples in addition to data collected from previous theses (Khandoker, 1997 and Douglas, 1999). The original 213 samples were run by ICP-AES with a reporting limit of 20 ppm, and only three samples had detected values. The original samples were tested again (2013) at a lower reporting limit of 0.2 ppm by ICP-MS, as were 42 new samples (2013), to better ascertain the natural levels of arsenic in undisturbed soils. The aim is to add to the existing DEQ data set, which has been used to establish new regulatory levels based on natural levels in the environment that are both safer and more economically viable than the former risk-based remediation levels (DEQ, 2013).
The maximum and mean concentrations, respectively, for each province (with high formation map unit) are 85.4 and 21.99 ppm for South Willamette Valley (Tfee), 45.4 and 5.42 ppm for the Klamath Mountains (Jub), 11.9 and 2.76 ppm for the Cascade Range (Tbaa), 10.6 and 5.15 ppm for the Coast Range (Ty), 2.32 and 1.29 ppm for the Basin and Range (Qba) and 1.5 and 1.20 ppm for the High Lava Plains (Tmv).
In addition, the distribution and variance of arsenic in the A and B soil horizons is assessed in this study by comparing deviation at a single site, and also by comparing A and B horizons of 119 PSU sites. One of 18 new sites sampled for this study (distinguished with the HH prefix), site HH11, was randomly chosen to evaluate differences at a single location. Site HH11 is an Inceptisol soil above volcanic rock (KJdv map unit) located at 275 meters elevation in Douglas County within the Klamath province. Five samples were taken from the A and from the B horizons at site HH11. The means and standard deviations were 3.74 ± 0.44 for the A horizon and 4.53 ± 0.39 for the B horizon. The consistency and low deviation within each horizon indicate that a single sample within a horizon is a good representative of that horizon and supports the field methodology used in this study of taking only one sample in the A horizon and one sample in the B horizon.
Wilcoxon Rank-Sum test determined that A and B horizons for the 119 sites that had data for both the A and B horizons were not statistically different (p-value 0.76). Arsenic concentration is not associated with a particular horizon for these sites. However, differentiation between soil horizons increases with age (Birkeland, 1999), as does accumulation of the iron oxides and sulfide minerals on clay surfaces (McLaren et al., 2006) which concentrate in the B horizon. These associations warrant further study to see how they relate to arsenic level, soil development and age in Oregon soils.
Lastly, this study statistically examines six potentially important environmental predictors of naturally occurring arsenic in southwestern Oregon: site elevation, geomorphic province, mapped rock type and age, and sample soil order and color (redness). A Classification and Regression Tree Model (CART) determined soil order, elevation and rock type to be of significant importance in determining arsenic concentrations in the natural environment. According to the regression tree, arsenic concentrations are greater within Alfisol and Ultisol/Alfisol and Vertisol soil orders, at lower elevations below 1,207 meters, and within soils from sedimentary, mixed volcanic/sedimentary and unconsolidated rock types.
31
Oxenberg, Tanya Palmateer. "The use of catchboxes to minimize the impact to the environment from testing depleted uranium penetrations". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/18219.
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32
Leung, Oi-kwan Winnie, e 梁愛群. "A preliminary study on the Hong Kong external trade of non-ferrous metal waste (and scrap) and other potentially hazardous wastematerials". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31253180.
Testo completo
33
Miller, Carla Joan. "Water quality and macroinvertebrate populations of Finley Creek before and after a hazardous waste cleanup". Virtual Press, 1988. http://liblink.bsu.edu/uhtbin/catkey/546147.
Testo completoAbstract (sommario):
Water samples and macroinvertebrates were collected from three stations of Finley Creek, Indiana before and after a surface cleanup of an adjacent hazardous waste disposal site. Water quality parameters: iron, total dissolved solids, conductance, hardness, total suspended solids and pH were compared between stations and years. The water quality above the landfill was high but decreased downstream. The water below the disposal site contained high levels of chemicals in both studies. However, the concentrations of chemicals were lower in the water two years after the cleanup.Numbers of macroinvertebrates and the number of taxa were determined and species diversity indicies were established. The results showed a statistically significant increase in macroinvertebrate taxa and mean species diversity indicies below the waste disposal site after the cleanup. These results indicate an improvement of water quality.Department of Natural Resources
34
Chan, Wai Fung. "The roles of arbuscular mycorrhizal fungi in arsenic uptake and tolerance of upland rice". HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1257.
Testo completo
35
Lake, Bjorn Anders. "The Use of Semipermeable Membrane Devices (SPMDS) for Monitoring Dioxin Levels in Maine Rivers". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/LakeBA2003.pdf.
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Kantachote, Duangporn. "The use of microbial inoculants to enhance DDT degradation in contaminated soil". Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phk165.pdf.
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Mbakwa, Emmanuel Fon. "Accumulation of lead and manganese in soil along the N1 highway in the City of Cape Town after the banning of leaded petrol in South Africa". Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/803.
Testo completoAbstract (sommario):
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Environmental Health
Faculty of Applied Sciences
Cape Peninsula University of TechnologySoil contamination by metals is a serious environmental problem that has significant implications for human health. Roadside soils have been shown to have considerable contamination due to depositions of metals by vehicles. Metal pollution poses significant environmental concerns because most metals are not biodegradable and often have long half-lives, thus predicating far reaching effects on biological systems, including the soil. Unleaded petrol has been available in South Africa since 1996. The conversion from leaded to unleaded petrol has been a slow process. Leaded petrol has been totally phased out since January 2006. The manganese-containing fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) that was introduced to automobile fuel formulae as an octane boosting and “anti-knock” agent, to replace or reduce the lead content in petrol, was officially approved in some developed countries. Despite the fact that metal contamination of soil has long been known, few studies have been carried out into its vertical distribution in the soil. The objectives of this investigation were: firstly, to assess the accumulation of lead and manganese in soil along the N1 highway; secondly, to determine the vertical distribution of lead and manganese in soil along the N1 highway; and thirdly, to compare the concentrations of lead and manganese in soil along the N1 highway, before and after the banning of leaded petrol in South Africa. Six soil samples were taken at each site approximately two meters from the road verges and at a depth of approximately 0-2cm of surface soil. The sampling period commenced on the 16th of February 2011 and ended on the 28th of December 2011. Once-off soil samples were also collected at sites 1, 5 and 6 at depths of 0-2cm, 30cm and 60cm, respectively. Samples were digested with 10 ml 55% nitric acid. Lead and manganese concentrations were determined by using Inductively Coupled Plasma Mass Spectrophotometer (ICP–MS). The mean concentrations of lead found in the roadside soils of the N1 highway ranged between 7.32mg/kg and 2068.31mg/kg and these were of high concentrations when compared to studies done in other countries. Results from the vertical distribution of lead investigation showed that lead concentrations ranged from 52.72mg/kg to 215.94mg/kg at surface level, from 15.80mg/kg to 164mg/kg at a depth of 30cm and from 14.06mg/kg to 216.07mg/kg at a depth of 60cm from the surface. It was also shown that there is a positive correlation between lead concentration and the amount of organic content (although not statistical), concluding that as the amount of organic content increases lead concentrations also increase. The mean manganese concentrations found in the roadside soils of the N1 ranged between 12.17mg/kg and 221.47mg/kg. The levels of manganese in the soil were found to be relatively low when compared to other studies an indication of mild to low metal contamination of the sampled soils. Results from the vertical distribution of manganese concentrations showed that concentrations in the soil ranged from 39.23 mg/kg to 63.32 mg/kg at surface level, from 14.4mg/kg to 310.86mg/kg for depths of up to 30cm, and from 4.42mg/kg to 343.96mg/kg for depths of up to 60cm. No relationships of manganese levels in the soil were found at any of the sites when sites were compared prior to the banning of lead and after the banning of lead despite the increased traffic volumes and, thus, increased MMT usage over the years, indicating that manganese contribution from MMT is very low and does not significantly increase soil contamination along the N1 highway. However, further investigations are needed into the future to monitor manganese contamination that may possibly occur.
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Lee, Huk-bun, e 李學斌. "Environmental economics: a framework for assessing the economic impacts of adopting biotechnologies in HongKong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B45013500.
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Li, Hui. "The role of arbuscular mycorrhizal fungi (AMF) on the tolerance and accumulation of arsenic in rice (Oryza sativa L.)". HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1409.
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Chow, Stephanie Stacey. "Effects of Biogeochemical and Physical Processes on the Transformation of Trace Metals at Oxic-Anoxic Interfaces in Aquatic Systems". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19705.
Testo completoAbstract (sommario):
Trace metals (e.g. Fe, Mn, Zn, Cu, Cd, Ni) are important micronutrients that have historically been regarded as toxic pollutants rather than essential components of riverine and estuarine environments. The toxicity and behavior of trace metals, in response to physical and biogeochemical processes, are determined by their individual physico-chemical properties. In this dissertation, the vertical transformation of trace metals across oxic-anoxic interfaces was investigated at two sites, a Fe-rich freshwater river with minimal sulfide and an estuary with elevated Mn and H2S concentrations.
Sediment profiles obtained from the Chattahoochee River showed that dissolved arsenic, present as As(V) only, is scavenged by Fe-oxides and accumulates directly below the sediment-water interface. Depth profiles also indicate that As(V) fluxes into the overlying water during baseflow conditions as well as after storm events. The significant correlation between Fe(II) and As(V) suggest that As(V) is released from Fe-oxides during their microbial reduction. By implementing a series of sediment incubations under increasing As(V) loads, it was determined that adsorption onto Fe-oxides and microbially mediated reductive dissolution of these mineral phases drive arsenic cycling in this sediment. These incubations also reveal for the first time that arsenic, even in low concentrations, n turn, arsenic loading impacts iron cycling by stimulating anaerobic respiration of Fe-oxides and promoting recrystallization of authigenic Fe-oxides, up to a toxicity threshold up to a few micromolar in concentrations.
A combination of in situ measurements with discrete water sampling was utilized to determine the effects of tidal cycling on the distribution of trace metals under changing redox conditions during two consecutive tidal cycles at Station 858 in the Chesapeake Bay. Estuarine circulation patterns driven by tidal oscillations, a defined pycnocline, and the shallow sill (~20 m) of the Chesapeake Bay promoted bottom water anoxia during the summer months that allowed dissolved sulfide and reduced manganese to accumulate below the oxycline. The distribution of barium (conservative freshwater tracer) and uranium (conservative seawater tracer) across the pycnocline over the two tidal cycles indicated that the source of dissolved species was surficial sediments. During ebb and flood tides, the shear stress from the bottom waters flowing over the sediment seems to episodically promote the advection of porewaters enriched in dissolved sulfide, manganese, uranium, barium, lead, chromium, and copper. The selective enrichment of these trace metals appears to be controlled by their reactivity with sulfide. In contrast, cobalt and nickel are retained in sediments by adsorbed or incorporated in FeS and FeS2, while arsenic co-precipitates with sulfide or iron sulfide minerals. Overall, this study demonstrates that natural aquatic systems are complex environments where the interplay between biological, chemical, and physical processes affects the distribution of trace metals over short time scales. While a great wealth of knowledge can be obtained by laboratory experiments with synthetic solutions or pure cultures of organisms, a combination of in situ measurements and incubations with real samples in necessary to characterize the processes regulating the cycling of trace metals in aquatic systems.
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Wong, Stephen W. "Reproductive toxicity and bioavailability of arsenic in contaminated artificial and natural soils using the earthworm". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79205.
Testo completoAbstract (sommario):
High concentrations of arsenic are found near gold-mine tailings. The most common form of arsenic found in soil is arsenate, which is a known toxicant. We used the standardised earthworm reproduction test for the species Eisenia andrei (E. andrei) to study the toxicity and bioavailability of arsenic-contaminated soil. Arsenic is toxic to earthworms as indicated by the decrease in survival and reproduction. Arsenic-spiked artificial soil was more toxic than arsenic-spiked field soil based on total arsenic concentration in soil. Moreover, soil from near mine tailings showed a reduced toxic effect despite its high soil arsenic concentration as compared to spiked field soil. Measurements of arsenic tissue concentrations in the earthworm indicated that uptake of arsenic into earthworm tissue was higher in spiked artificial soil as compared to spiked field soil and that the maximal body burden was 396 mug As/g dry tissue weight. However, when considering tissue arsenic concentration, spiked field soil is more toxic than spiked artificial soil. Therefore the tissue rather than soil content may better reflect the magnitude of arsenic toxicity to E. andrei.
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Annarapu, Shashidhar. "Thermal Analysis of Binding of Organic Pollutants to Titanium Dioxide". TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1338.
Testo completoAbstract (sommario):
Conventional waste water treatment processes are not completely effective in removing highly stable organic compounds. Photocatalytic degradation on titanium dioxide is a possible alternative technique for many classes of these compounds. Several studies have been done by other researchers to study mechanisms of photocatalytic degradation, which occurs either through direct oxidation by holes or via indirect oxidation by radical messengers. Titanium dioxide can oxidize substrates directly through hole oxidation mechanisms or indirectly through free radical mechanisms. Substrates must bind onto the catalyst surface to undergo direct oxidation by holes. Thermogravimetric analysis (TGA) was performed on four different classes of compounds; iodinated contrast agents (iohexol and diatrizoate), polycyclic aromatic hydrocarbons (perylene and pyrene), the antibacterial agent triclosan and the pesticide atrazine, to investigate which of the compounds are adsorbed on the surface of titanium dioxide to undergo direct oxidation through electron holes. Differential scanning calorimetry (DSC) was conducted on triclosan and atrazine to determine if the desorption reaction is endothermic or exothermic. Powder X-ray diffraction was performed on all four classes of compounds to observe diffraction pattern of these compounds.
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Gil, Maria Doralice Maciel. "Relações entre fatores socioeconômicos e a geração de resíduos sólidos domiciliares - Vacaria". reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1793.
Testo completoAbstract (sommario):
Uma das grandes preocupações ambientais está relacionada à geração exacerbada de resíduos sólidos no âmbito domiciliar, como decorrência os impactos ambientais ocasionados pelo descarte inadequado dos mesmos. Estudos sobre geração de resíduos sólidos e fatores socioeconômicos são importantes e necessários para o entendimento do poder de consumo da população e sua relação com a poluição ambiental. O objetivo do estudo é analisar a relação que é estabelecida entre a geração dos resíduos sólidos domiciliares e fatores socioeconômicos de dois bairros predominantemente residenciais do município de Vacaria–RS. É realizada a identificação das características locais, composição gravimétrica dos resíduos sólidos domiciliares e a geração per capita de resíduos sólidos da população dos bairros. Mediante a realização de entrevista nos domicílios dos bairros foram identificadas as características socioeconômicas (escolaridade, renda, composição da família e a inserção da mulher no mercado de trabalho). Para a determinação da composição gravimétrica dos resíduos sólidos domiciliares utilizou-se o método de quarteamento. Os resíduos provenientes da coleta de resíduos misturados e da coleta seletiva de resíduos recicláveis de ambos os bairros foram caracterizados durante duas semanas (inverno e verão). Os diferentes componentes presentes nos resíduos foram identificados, quantificados e categorizados. Variações significativas na geração de resíduos foram identificadas como o descarte de eletrônicos, de medicamentos, excrementos de animais e de vidros pelo bairro de alto poder aquisitivo. No bairro de poder aquisitivo menor a presença de materiais têxteis, couro e borracha foram expressivos. A categoria biodegradável (incluindo resíduos alimentares), foi significativa em ambos os bairros. A geração per capita dos resíduos da população de poder aquisitivo maior é de 1,428 kg/hab.dia e no poder aquisitivo menor é de 0,212 kg/hab.dia, evidenciando a relação entre renda, escolaridade e composição familiar e impactos ambientais. Para estudos futuros, recomenda-se analisar a influência dos membros da família sobre geração de resíduos, como seus hábitos e comportamentos em relação ao consumo, desperdício e descarte de bens.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2017-03-08T14:18:06Z No. of bitstreams: 1 Dissertacao Maria Doralice Maciel Gil.pdf: 3402845 bytes, checksum: c260b5eefe3f7712fed546ad09bc2861 (MD5)
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One of the main environmental concerns is associated with the excessive amounts of municipal solid waste (MSW) and the environmental impacts caused by inappropriate disposal methods. Studies about the generation of solid waste and socioeconomic factors are important and necessary to understand the relationship between purchase power of a population and environmental pollution. The objective of the present study was to analyze the relationship between generation of MSW and socioeconomic variables in two predominantly residential neighborhoods in the municipality of Vacaria, state of Rio Grande do Sul, Brazil. The characteristics of each neighborhood were identified, and the gravimetric composition of MSW and the per capita generation of solid waste in the two neighborhoods were established. The inhabitants of both neighborhoods were interviewed, and the data obtained were used to characterize the socioeconomic features of these populations (literacy, income, family structure, role of women in the job market). The gravimetric composition of MSW was established by quartering. Garbage and recyclable waste from both neighborhoods were characterized during two weeks (in winter and in summer). The various components of MSW were identified, quantified, and classified. Significant differences in MSW composition such as the presence of electronic waste, medical drugs, animal excrement, and glassware were observed in the high purchase power neighborhood. In the low purchase power neighborhood, the presence of textiles, leather, and rubber was substantial. Biodegradable waste (including food remains) was significantly present in the MWS of both neighborhoods. Per capita generation of MSW in the high and low purchase power neighborhoods was 1,428 kg, day and 212 kg. day, respectively, revealing the relationship between income, literacy, family structure, and environmental impact. Further studies should evaluate the influence of family members on waste generation, including consumer habits and behaviors concerning wasting and disposal of goods.
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Kwok, Hon-chiu, e 郭漢超. "An overview of chemical waste management of printed circuit board manufacturing in Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31253428.
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Pasinato, Tatiana Lúcia Strapazzon. "O sistema de produção dos têxteis no Brasil : a legislação e a cadeia do algodão frente à teoria do risco e aos impactos socioambientais". reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1418.
Testo completoAbstract (sommario):
No presente estudo, analisam-se os danos ambientais resultantes do cultivo do algodão, provenientes do hiperconsumismo e dos resíduos sólidos têxteis dessa fibra natural de maior representatividade mundial. Em um primeiro momento, analisou-se a Teoria do Risco, traçada como ponto definidor e fundamental para o decorrer do estudo, e apresentada como adequada para embasar a análise dos riscos e danos ambientais causados pela produção do algodão, pelos seus resíduos e pelo hiperconsumismo. Em um segundo passo, trabalha-se sobre as formas de produção do algodão no Brasil, trazendo-se os benefícios do cultivo orgânico, e a abordagem acerca da crescente transgenia na cotonicultura. Aborda-se a intensa utilização de agrotóxicos, dificultando a existência de um ciclo sustentável. Em seguida, foca-se nos impactos ambientais causados pela indústria têxtil, enfatizando-se o tema dos resíduos sólidos têxteis com origem no algodão. O método utilizado é o analítico dedutivo, tendo como fundamento a pesquisa bibliográfica explorativa. Por final, revela-se a e permissibilidade jurídica quando do acolhimento dos métodos tradicionais utilizados no desenvolvimento das lavouras algodoeiras, principalmente quanto ao alto nível de agrotóxicos. Os resíduos têxteis do algodão, da indústria e do consumidor são pouco usados a programas sociais de reaproveitamento, entretanto continuam como problema social, haja vista que a Política Nacional dos Resíduos Sólidos não conduziu a uma solução prática. Reconhece-se que o desleixo com os danos ambientais é imenso na sociedade de risco da modernidade, caracterizada pelo avanço capitalista. A trajetória do hiperconsumo expõe uma conduta centralizada no individualismo social ainda que diante de catástrofes recorrentes.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-12-09T13:06:59Z No. of bitstreams: 1 Dissertacao Tatiana Lucia Strapazzon Pasinato.pdf: 1631041 bytes, checksum: 4f76fbd7e71fd11aa1cd50bf1aa9c019 (MD5)
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In the present study, the environmental damages caused by the cultivation of cotton from the hyperconsumerism and solid textile residues of this natural fiber of greater world-wide importance are analyzed. At first, we analyzed the Risk Theory, drawn as a defining and fundamental point for the course of the study, and presented as adequate to support the analysis of the environmental risks and damages caused by the production of cotton, its residues and hyperconsumption . In a second step, we work on the ways of producing cotton in Brazil, bringing the benefits of organic cultivation, and the approach to growing cotton-growing transgenics. It addresses the intense use of pesticides, making difficult the existence of a sustainable cycle. Next, it focuses on the environmental impacts caused by the textile industry, emphasizing the theme of textile solid waste from cotton. The method used is the deductive analytic, based on the exploratory bibliographical research. Finally, it reveals the legal and legal permissibility when hosting the traditional methods used in the development of cotton crops, especially as regards the high level of pesticides. Textile waste from cotton, industry and consumers is little used for social reuse programs; however, they remain a social problem, since the National Solid Waste Policy did not lead to a practical solution. It is recognized that neglect of environmental damage is immense in the risk society of modernity characterized by capitalist advancement. The trajectory of hyperconsumption exposes a behavior centered on social individualism even in the face of recurrent disasters.
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Haffert, Laura, e n/a. "Metalloid mobility at historic mine and industrial processing sites in the South Island of New Zealand". University of Otago. Department of Geology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090921.144328.
Testo completoAbstract (sommario):
Rocks of the South Island of New Zealand are locally enriched in metalloids, namely arsenic (As), antimony (Sb) and boron (B). Elevated levels of As and Sb can be found in sulphide minerals mostly in association with mesothermal gold deposits, whereas B enrichment occurs in marine influenced coal deposits. The mobility of these metalloids is important because they can be toxic at relatively low levels (e.g. for humans >0.01 mg/L of As). Their mobilisation occurs naturally from background weathering of the bedrock. However, mining and processing of coal and gold deposits, New Zealand's most economically important commodities, can significantly increase metalloid mobility. In particular, historic mines and associated industrial sites are known to generate elevated metalloid levels because of the lack of site remediation upon closure. This work defines and quantifies geological, mining, post-mining and regional processes with respect to metalloid, especially As, mobility.
At the studied historic gold mines, the Blackwater and Bullendale mines, Sb levels in mineralised rocks were generally negligible (<14 ppm) compared to As (up to 10,000 ppm). Thus, Sb concentrations in solids and in water were too low to yield any meaningful information on Sb mobility. In contrast, dissolved As concentrations downstream from mine sites were found to be very high (up to 59 mg/L) (background = 10⁻� mg/L). In addition, very high As concentrations were found in residues (up to 40 wt%) and site substrate (up to 30 wt%) at the Blackwater processing sites (background < 0.05 wt%). Here, roasting of the gold ore converted the orginal As mineral, arsenopyrite, into the mineral arsenolite (As[III] trioxide polymorph) and volatilised the sulphur. The resultant sulphur-defficient chemical system is driven by arsenolite dissolution and differs significantly from mine sites where arsenopyrite is the main As source.
Arsenolite is significantly more soluble than arsenopyrite. In the surficial environment, arsenolite dissolution is limited by kinetics only, which are slow enough to preserve exposed arsenolite over decades in a temperate, wet climate. This process results in surface waters with up to ca. 50 mg/L dissolved As. In reducing conditions, dissolved As concentrations are also controlled by the solubility of arsenolite producing As concentrations up to 330 mg/L.
Field based cathodic stripping voltammetry showed that the As[III]/As[V] redox couple, in particular the oxidation of As[III], has a major control on system pH and Eh. Site acidification is mainly caused by the oxidation of As[III], resulting in a close link between As[V] concentrations and pH. Similarly, a strong correlation between calculated (Nernstian) and measured (electrode) Eh was found in the surface environment, suggesting that the overall Eh of the system is, indeed, defined by the As[III]/As[V] redox couple.
Once the metalloid is mobilised from its original source, its mobility is controlled by at least one of the following attenuation processes: (a) precipitation of secondary metalloid minerals, (b) co-precipitation with - or adsorption to - iron oxyhydroxide (HFO), or (c) dilution with background waters. The precipitation of secondary minerals is most favoured in the case of As due to the relatively low solubility of iron arsenates, especially at low pH (~0.1 mg/L). Observations suggest that scorodite can be the precursor phase to more stable iron arsenates, such as kankite, zykaite, bukovskyite or pharmacosiderite and their stability is mainly controlled by pH, sulphur concentrations and moisture prevalence. Empirical evidence indicates that the sulphur-containing minerals zykaite and bukovskyite have a similar pH dependence to scorodite with solubilities slightly lower than scorodite and kankite. If dissolved As concentrations decline, iron arsenates potentially become unstable. Their dissolution maintains a pH between 2.5 and 3.5. This acidification process is pivotal with respect to As mobility, especially in the absence of other acidification processes, because iron arsenates are several orders of magnitude more soluble in circum-neutral pH regimes (~100 mg/L). From this, it becomes apparent that external pH modifications, for example as part of a remediation scheme, can significantly increase iron arsenate solubility and resultant As mobility. In contrast to As, the precipitation of secondary Sb and B minerals is limited by their high solubilities, which are several orders of magnitude higher than for iron arsenates. Thus, secondary Sb and B minerals are restricted to evaporative waters, from which they can easily re-mobilised during rain events.
Metalloid adsorption to HFO is mainly controlled or limited by the extent of HFO formation, which in turn is governed by the availability of Fe and prevailing Eh-pH conditions. Thus, mineralisation styles and associated geochemical gradients, in particular pyrite abundance, can control the amount of HFO and consequent metalloid attenuation, and these can vary even within the same goldfleld. Furthermore, it was found that there is a mineralogical gradation between ferrihydrite with varying amounts of adsorbed As, amorphous iron arsenates and crystalline iron arsenates, suggesting that the maturity of mine waste is an important factor in As mineralogy.
Once dissolved metalloids enter the hydrosphere, dilution is the main control on metalloid attenuation, which is especially pronounced at the inflow of tributaries. Dilution is, therefore, closely related to the size and frequency of these tributaries, which in turn are controlled by the regional topography and climate. Dilution is a considerably less effective attenuation mechanism and anomalous metalloid concentrations from mining related sites can persist for over 10 km downstream.
The complex and often inter-dependent controls on metalloid mobility mean that management decisions should carefully consider the specific site geochemistry to minimize economic, health and environmental risks that can not be afforded.
On a regional scale, background metalloid flux determines the downstream impact of an anomalous metalloid source upstream. For example, the Bullendale mine is located in a mountainous region, where rapidly eroding slopes expose fresh rock and limit the extent of soil cover and chemical weathering. Consequently, the background As flux is relatively low and As point sources, such as the Bullendale mine, present a significant contribution to the downstream As flux. In contrast, the bedrock at the Blackwater mine has undergone deep chemical weathering, resulting in an increased background mobilisation of As. Thus, the Prohibition mill site discharge, for example, contributes only about 10% to the downstream As flux. This information is relevant to site management decisions because the amount of natural background metalloid mobilisation determines whether site remediation will influence downstream metalloid chemistry on a regional scale.
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Rinquest, Zainab. "Poultry slaughterhouse wastewater treatment using a static granular bed reactor (Sgbr) coupled with a hybrid sidestream membrane bioreactor". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2638.
Testo completoAbstract (sommario):
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.An increase in the demand for poultry products coupled with the potable water shortages currently experienced in South Africa (SA), attributed to climate change among other factors, makes it crucial for SA to develop water conservation strategies to minimize potable water consumption by water-intensive industries, such as the poultry industry. The development of innovative wastewater treatment processes is therefore paramount in attempting to counteract the large quantity of wastewater generated as well as to manage the environmental health concerns arising from poultry slaughterhouse wastewater (PSW) discharge into the environment. Moreover, increasing wastewater treatment costs and the implementation of increasingly stringent government legislation to mitigate environmental pollution whilst minimizing fresh water source contamination, requires that wastewater such as PSW, be adequately treated prior to discharge. This study, investigated the feasibility of treating PSW from a poultry slaughterhouse to: 1) a water quality standard compliant with industrial wastewater discharge standards and 2) for possible re-use purposes. The performance of a lab-scale PSW treatment system consisting of an anaerobic static granular bed reactor (SGBR) followed by single stage nitrificationdenitrification (SSND) bioreactor and sidestream ultrafiltration membrane module (ufMM) post-treatment systems, were evaluated, with the objective being to: assess the treatment efficiency of the individual treatment systems namely; the SGBR, SSND bioreactor, and ufMM, under varying operational conditions, as well as to determine the performance of the overall designed PSW treatment system. The down-flow SGBR (2 L) was used to reduce the organic matter (COD, BOD5, and FOG) and total suspended solids (TSS) in the PSW. Anaerobic granules from a full-scale mesophilic anaerobic reactor treating brewery wastewater were used to inoculate the SGBR, and the PSW used as feed was obtained from a local poultry slaughterhouse (Western Cape, South Africa). The SGBR was operated continuously at mesophilic temperature (35-37 °C) without pH modification and under varying HRTs (24, 36, 48, 55, and 96 h) and OLRs (0.73 to 12.49 g COD/Lday), for a period of 138 days. The optimization of the SGBR, with regard to a suitable HRT and OLR, was determined using response surface methodology (RSM) and Design Expert® 10.0.3 statistical software. Periodic backwashing of the SGBR system was performed using stored effluent, i.e. treated PSW.
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Colon, i. Bosch Mireia. "Analytical strategies based on inductively coupled plasma sprectroscopy (ICP) and diffusive gradients in thin fims (DGT) techniques for the assessment of environmental pollution indicators". Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/84050.
Testo completoAbstract (sommario):
In this thesis, simple methods to determine sulfide at low levels (µg L-1) in aqueous samples and sediments by water free hydrogen sulfide vapor generation using a commercially available vapor generation accessory have been developed. The hydrogen sulfide is then introduced in the ICP-QMS, equipped with an octopole collision/reaction cell which is vented with hydrogen and helium gases, or in the ICP-AES where the optical path between the plasma and the monochromator is purged with nitrogen. Moreover some studies have been conducted for the determination of arsenic by ICP-MS in natural waters with high sodium and chloride content. Spectral and non spectral interferences on arsenic measurement have been investigated and different experiments have been developed to solve such interferences (optimizations of the cell collision conditions, arithmetic corrections, introduction of small amounts of alcohol). Finally, the use of the DGT technique (diffusive gradients in thin films) has been evaluated in acidic samples and mining wastes for the firs time.En aquesta tesi, s’han desenvolupat mètodes senzills per a la determinació de sulfur a baixes concentracions (µg L-1) en mostres aquoses i sediments mitjançant la generació de sulfur d’hidrogen, utilitzant un accessori de generació d’hidrurs comercial. Un cop format el sulfur d’hidrogen, aquest es pot introduir a l’ICP-QMS, equipat amb una cel•la de col•lisió/reacció o a l’ICP-AES amb el pas entre el plasma i el monocromador purgat amb nitrogen. També s’han fet alguns estudis per determinar arsènic amb ICP-MS en aigües naturals amb alt contingut de sodi i clor. S’han estudiat les interferències espectrals i no espectrals sobre aquest element i s’han dut a terme diferents experiments per a resoldre-les (optimització de la cel•la de col•lisió, aplicació de correccions matemàtiques, introducció de petites quantitats d’alcohol). Finalment, s’ha avaluat l’ús de la tècnica de DGT (diffusive gradients in thin films) en mostres àcides (pHs de 5 a 10) i residus de mineria per primera vegada.
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Patterson, Shane, e University of Lethbridge Faculty of Arts and Science. "The agronomic benefit of pulp mill boiler wood ash". Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2001, 2001. http://hdl.handle.net/10133/127.
Testo completoAbstract (sommario):
Land application of wood ash is becoming more appealing, as a disposable alternative, to landfilling options. It is estimated that 110,000 tonnes of wood ash is produced annually in Alberta by cogeneration systems, a large percentage produced in Central and Peace River Regions of Alberta. Alkaline (pH-13) properties and nutrient content of wood ash provides an alternative for the acidic and nutrient deficient soils within these regions. The objective of this field study was to determine the effect wood ash applications would have under field conditions on: the chemical and physical properties of soils; barley dry matter production; grain and seed yield of barley and canola; and the nutrient and metal uptake by crop tissue. Ash applications significantly increased dry matter and seed yield, improved crop nutrient quality, increased soil pH and improved soil nutrient availability, while not infringing on any environmental regulations.xxiii, 142 leaves : ill. ; 28 cm.
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Sattar, Mohamed Shaheen. "An environmental impact perspective of the management, treatment, and disposal of hazardous pharmaceutical compounds generated as medical waste at selected hospitals in Cape Town, South Africa". Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2012.
Testo completoAbstract (sommario):
Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2011.Pharmaceuticals have been formulated to influence physiological systems in humans, animals, and microbes but have never been considered as potential environmental pollutants by healthcare professionals. The human body is not a barrier to chemicals, but is permeable to it. Thus after performing their in-vivo functions, pharmaceutical compound introduced into the body, exit mainly via urine and faeces. Sewage therefore contains highly complex mixtures of chemicals in various degrees of biological potency. Sewage treatment works including those in South Africa, on the other hand, are known to be inefficient in removing drugs from sewage and consequently either the unmetabolised pharmaceutical compounds or their metabolites emerge in the environment as pollutants via several trajectories. In the environment, the excreted metabolites may even undergo regeneration to the original parent molecule under bacterial influence, resulting in "trans-vivo-pharmaceutical-pollution-cycles". Although all incinerators are known to generate toxins such dioxins and furans from the drugs they incinerate, all the medicines disposed by the hospitals under research, were incinerated, as the preferred option of disposal. The incineration process employed was found to be environmentally unsafe. Expired and unused medicines which the general public discard as municipal solid waste become landfilled. Because many landfill sites are not appropriately engineered, the unwanted drugs landfilled therein, leach into the surrounding ground water, which is the influent source of water treatment plants. Water treatment plants, including those in South Africa, are also inefficient in eliminating pharmaceutical compounds, releasing them in sub-therapeutic concentrations into potable tap water as pollutants, the full effects of which are yet to be determined.