Acid rain and transported air pollutants : implications for public policy.

Mode of access: Internet.

Essays on Environmental and Health Economics

Thesis (Ph.D.)--University of Washington, 2016-06

Postharvest characteristics and handling of litchi fruit - an overview

Litchi ( Litchi chinensis Sonn.) is a tropical to subtropical crop that originated in South-East Asia. Litchi fruit are prized on the world market for their flavour, semi-translucent white aril and attractive red skin. Litchi is now grown commercially in many countries and production in Australia, China, Israel, South Africa and Thailand has expanded markedly in recent years. Increased production has made significant contributions to economic development in these countries, especially those in South-East Asia. Non-climacteric litchi fruit are harvested at their visual and organoleptic optimum. They are highly perishable and, consequently, have a short life that limits marketability and potential expansion of demand. Pericarp browning and pathological decay are common and important defects of harvested litchi fruit. Postharvest technologies have been developed to reduce these defects. These technologies involve cooling and heating the fruit, use of various packages and packaging materials and the application of fungicides and other chemicals. Through the use of fungicides and refrigeration, litchi fruit have a storage life of about 30 days. However, when they are removed from storage, their shelf life at ambient temperature is very short due to pericarp browning and fruit rotting. Low temperature acclimation or use of chitsoan as a coating can extend the shelf life. Sulfur dioxide fumigation effectively reduces pericarp browning, but approval from Europe, Australia and Japan for this chemical is likely to be withdrawn due to concerns over sulfur residues in fumigated fruit. Thus, sulfur-free postharvest treatments that maintain fruit skin colour are increasingly important. Alternatives to SO2 fumigation for control of pericarp browning and fruit rotting are pre-storage pathogen management, anoxia treatment, and dipping in 2% hydrogen chloride solution for 6-8 min following storage at 0 degrees C. Insect disinfestation has become increasingly important for the expansion of export markets because of quarantine issues associated with some fruit fly species. Thus, effective disinfestation protocols need to be developed. Heat treatment has shown promise as a quarantine technology, but it injures pericarp tissue and results in skin browning. However, heat treatment can be combined with an acid dip treatment that inhibits browning. Therefore, the primary aim of postharvest litchi research remains the achievement of highly coloured fruit which is free of pests and disease. Future research should focus on disease control before harvest, combined acid and heat treatments after harvest and careful temperature management during storage and transport.

Pulling Back the Veil: The Characterization and Habitability of Enshrouded Worlds

Thesis (Ph.D.)--University of Washington, 2016-08

Methods to evidence mechanical injuries on "Packham's Triumph" pears.

2016

Chemical and aromatic characteristics of Brazilian tropical wines.

Traditional winegrowing areas are located in temperate climate zones and allow to produce grapes only once per year. Tropical wines have been elaborated in India, Thailand, Venezuela and Brazil and present another kind of viticulture, as compared with countries located in temperate climate zones. Northeast of Brazil started wine production twenty six years ago. This region vines can produce two or three crops per year, depending of the cycle of different cultivars. Harvests can be scaled throughout the year, mainly between May and December, corresponding to the dry season. Red, white, rosé and sparkling wines are being elaborated in the region. The objective of this work was to determine the physico-chemical and aromatic characteristics of some tropical wines elaborated in Northeast of Brazil, with grapes harvested in November 2008. Wines were elaborated using traditional method with control of the alcoholic and malolactic fermentation temperatures, at 25 and 18ºC for red wines, respectively, and at 18ºC for alcoholic fermentation of the white wines. After stabilization and bottling and wines were analyzed to determine physico-chemical characteristics, like alcohol degree, pH, total and volatile acidities, dry extract, sulfur dioxide, total anthocyanin and total phenol index. Aromatic profile was determined by gas chromatography, while 19 esters and 6 superior alcohols were identified. Wines presented different chemical and aromatic characteristics according to different grape cultivars.

Low-Temperature Fluorination Of Sulfur-Compounds With Elemental Fluorine

Low temperature fluorination technique is adopted for fluorination of the following sulphur compounds in freon-11 medium (1) Sulphur dioxide (2) Thionyl chloride (3) Sulphuryl chloride (4) Tetrasulphur tetra nitride and (5) Sulphur bromide. All the compounds undergo oxidative fluorination to give rise to sulphur-fluorine compounds except sulphuryl chloride which resists fluorination. Sulphuryl chloride thus behaves as a good solvent medium for fluorination of other reactive compounds like elemental sulphur. Details of the experimental procedures adopted and the identification of the products will be presented

Atomic Layer Deposition and Photocatalytic Properties of Titanium Dioxide Thin Films

Photocatalytic TiO2 thin films can be highly useful in many environments and applications. They can be used as self-cleaning coatings on top of glass, tiles and steel to reduce the amount of fouling on these surfaces. Photocatalytic TiO2 surfaces have antimicrobial properties making them potentially useful in hospitals, bathrooms and many other places where microbes may cause problems. TiO2 photocatalysts can also be used to clean contaminated water and air. Photocatalytic oxidation and reduction reactions proceed on TiO2 surfaces under irradiation of UV light meaning that sunlight and even normal indoor lighting can be utilized. In order to improve the photocatalytic properties of TiO2 materials even further, various modification methods have been explored. Doping with elements such as nitrogen, sulfur and fluorine, and preparation of different kinds of composites are typical approaches that have been employed. Photocatalytic TiO2 nanotubes and other nanostructures are gaining interest as well. Atomic Layer Deposition (ALD) is a chemical gas phase thin film deposition method with strong roots in Finland. This unique modification of the common Chemical Vapor Deposition (CVD) method is based on alternate supply of precursor vapors to the substrate which forces the film growth reactions to proceed only on the surface in a highly controlled manner. ALD gives easy and accurate film thickness control, excellent large area uniformity and unparalleled conformality on complex shaped substrates. These characteristics have recently led to several breakthroughs in microelectronics, nanotechnology and many other areas. In this work, the utilization of ALD to prepare photocatalytic TiO2 thin films was studied in detail. Undoped as well as nitrogen, sulfur and fluorine doped TiO2 thin films were prepared and thoroughly characterized. ALD prepared undoped TiO2 films were shown to exhibit good photocatalytic activities. Of the studied dopants, sulfur and fluorine were identified as much better choices than nitrogen. Nanostructured TiO2 photocatalysts were prepared through template directed deposition on various complex shaped substrates by exploiting the good qualities of ALD. A clear enhancement in the photocatalytic activity was achieved with these nanostructures. Several new ALD processes were also developed in this work. TiO2 processes based on two new titanium precursors, Ti(OMe)4 and TiF4, were shown to exhibit saturative ALD-type of growth when water was used as the other precursor. In addition, TiS2 thin films were prepared for the first time by ALD using TiCl4 and H2S as precursors. Ti1-xNbxOy and Ti1-xTaxOy transparent conducting oxide films were prepared successfully by ALD and post-deposition annealing. Highly unusual, explosive crystallization behaviour occurred in these mixed oxides which resulted in anatase crystals with lateral dimensions over 1000 times the film thickness.

Tracking the Fate of Microbially Sequestered Carbon Dioxide in Soil Organic Matter

The microbial contribution to soil organic matter (SOM) has recently been shown to be much larger than previously thought and thus its role in carbon sequestration may also be underestimated. In this study we employ C-13 ((CO2)-C-13) to assess the potential CO2 sequestration capacity of soil chemoautotrophic bacteria and combine nuclear magnetic resonance (NMR) with stable isotope probing (SIP), techniques that independently make use of the isotopic enrichment of soil microbial biomass. In this way molecular information generated from NMR is linked with identification of microbes responsible for carbon capture. A mathematical model is developed to determine real-time CO2 flux so that net sequestration can be calculated. Twenty-eight groups of bacteria showing close homologies with existing species were identified. Surprisingly, Ralstonia eutropha was the dominant group. Through NMR we observed the formation of lipids, carbohydrates, and proteins produced directly from CO2 utilized by microbial biomass. The component of SOM directly associated with CO2 capture was calculated at 2.86 mg C (89.21 mg kg(-1)) after 48 h. This approach can,differentiate between SOM derived through microbial uptake of CO2 and other SOM constituents and represents a first step in tracking the fate and dynamics of microbial biomass in soil.

Isotopic composition of oxygen, carbon, and sulfur in interstitial water and cores at DSDP Leg 59 Holes

Comprehensive isotopic studies based on data from the Deep Sea Drilling Project have elucidated numerous details of the low- and high-temperature mechanisms of interaction between water and rocks of ocean crustal seismic Layers 1 and 2. These isotopic studies have also identified climatic changes during the Meso-Cenozoic history of oceans. Data on the abundance and isotopic composition of sulfur in the sedimentary layer as well as in rocks of the volcanic basement are more fragmentary than are oxygen and carbon data. In this chapter we specifically concentrate upon isotopic data related to specific features of the mechanisms of low-temperature interaction of water with sedimentary and volcanogenic rocks. The Leg 59 data provide a good opportunity for such lithologic and isotopic studies, because almost 600 meters of basalt flows and sills interbedded with tuffs and volcaniclastic breccias were cored during the drilling of Hole 448A. Moreover, rocks supposedly exposed to hydrothermal alteration play an important role at the deepest horizons of that mass. Sulfur isotopic studies of the character of possible biogenic processes of sulfate reduction in sediments are another focus, as well as the nature and origin of sulfide mineralization in Layer-2 rocks of remnant island arcs. Finally, oxygen and carbon istopic analyses of biogenic carbonates in the cores also enabled us to investigate the effects of changing climatic conditions during the Cenozoic. These results are compared with previous data from adjacent regions of the Pacific Ocean. Thus this chapter describes results of isotopic analyses of: oxygen and sulfur of interstitial water; oxygen and carbon of sedimentary carbonates and of calcite intercalations and inclusions in tuffs and volcaniclastic breccias interbedded with basalt flows; and sulfur of sulfides in these rocks.

Chemical composition and sulfur-isotope ratios in DSDP Legs 69-and 70

As part of the geochemical-petrological study of basalts recovered from DSDP Hole 504B (Leg 70) on the southern flank of the Costa Rica Rift, we investigated specially the relationships between the distribution and isotopic composition of sulfur of scattered and vein sulfides on the one hand, and the observed pattern and processes of secondary alterations on the other. The following groups of observations are essential: (1) variations in the contents and isotopic composition of sulfur of different forms of sulfides are clearly interrelated and are observed solely in porous horizons established on the basis of detailed geophysical experiments; (2) the enrichment of sulfides in the light sulfur isotope decreases from the upper to the lower horizons, and within horizons in the direction of the less-altered rock; (3) the increase of d34S values of scattered sulfides in individual permeable zones parallels a decrease in the degree of iron oxidation in the contents of crystallization water, and in the concentrations of Mg, K, and Li in the rock.