Dissolved organic matter (DOM) is a complex mixture of organic compounds and represents the largest reservoirs of carbon (C) on earth. Particulate organic matter (POM) is another important carbon component in C cycling and controls a variety of biogeochemical processes. Estuaries, as important interfaces between land and ocean, play important roles in retaining and transforming such organic matter (OM) and serve as both sources and sinks of DOM and POM. There is a diverse array of both autochthonous and allochthonous OM sources in wetland/estuarine ecosystems. A comprehensive study on the sources, transformation and fate of OM in such ecosystems is essential in advancing our understanding of C cycling and better constraining the global C budget. In this work, DOM characteristics were investigated in different estuaries. Dissolved organic matter source strengths and dynamics were assessed in a seagrass-dominated subtropical estuarine lagoon. DOM dynamics controlled by hydrology and seagrass primary productivity were confirmed, and the primary source of DOM was quantified using the combination of excitation emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC) and stable C isotope analysis. Seagrass can contribute up to 72% of the DOM in the study area. The spatial and temporal variation of DOM dynamics was also studied in a freshwated dominated estuary fringed with extensive salt marshes. The data showed that DOM was primarily derived from freshwater marshes and controlled by hydrology while salt marsh plants play a significant role in structuring the distribution patterns of DOM quality and quantity. The OM dynamics was also investigated in a mangrove-dominate estuary and a comparative study was conducted between the DOM and POM pools. The results revealed both similarity and dissimilarity in DOM and POM composition. The dynamics of both OM pools are largely uncoupled as a result of source differences. Fringe mangrove swamps are suggested to export similar amounts of DOM and POM and should be considered as an important source in coastal C budgets. Lastly, chemical characterizations were conducted on the featured fluorescence component in OM in an attempt to better understand the composition and origins of the specific PARAFAC component. The traditionally defined ‘protein-like’ fluorescence was found to contain both proteinaceous and phenolic compounds, suggesting that the application of this parameter as a proxy for amino acid content and bioavailability may be limited.

The advancements in the field of analytical chemistry, and especially mass spectrometry, have been redefining the field of contaminant detection. While more traditional analysis was sufficient to screen for a small number of well-known compounds, new techniques such as high-resolution mass spectrometry, have enabled a fairly comprehensive screening for previously unknown contaminants. This is enormously beneficial with respect to the analysis of water, air, or soil quality in a society that continuously introduces novel anthropogenic compounds into the environment. This dissertation, thus, focused on the analysis of the uncharacterized portion of compounds in two types of complex environmental matrices (i.e., crude oil and wastewater). First, targeted and non-targeted analyses were used in order to characterize a crude oil weathering series. Traditional techniques were used for the analysis of well-known oil components and led to the confirmation of biodegradation and photo-degradation trends. An ultrahigh-resolution mass spectrometric analysis was carried out in conjunction with several visualization plots in order to search for unknown compounds. While the study successfully detected a drastic increase in oxygenated components (likely ketones, quinones, and carboxylic acids), it also revealed severe limitations in the state of the art non-targeted crude oil analysis. Some of these limitations were explored in an in-depth atmospheric pressure ionization study of model petroleum compounds, and the dependence of ionization efficiency on numerous factors (e.g., size, heteroatom content, and methylation level) was shown. Since disregarding these intrinsic limitations leads to severely biased conclusions, these results provide crucial information for future crude oil characterization studies. Lastly, suspected and non-targeted analyses were used to evaluate contamination levels in wastewater-impacted interrelated water samples. A significant number of persistent compounds were tentatively identified, which represents an area of environmental concern that needs to be addressed further. Overall, this dissertation successfully applied non-targeted (in addition to targeted) analysis in order to screen for non-characterized compounds in crude oil and wastewater affected water samples. By doing so, the great potential of the growing field of non-targeted screening in order to expand the range of contaminants to include previously unknown and emerging compounds was highlighted.

No description available.

Today, great effort is made for the protection of cultural heritage. Natural or anthropogenic factors decrease the conservation condition of the cultural artefacts, while their protection and survival mainly depends on political, financial, and technological issues. This project concerns the influence of the environmental pollution on cultural heritage and focuses on the potential effect of chronic petroleum hydrocarbon ground leakage on the subterranean parts of stone monuments. Bibliographic research revealed that there are many references to the effect of air pollution on building stone. However, research has not been expanded to the field of underground pollution in relation to the condition of the stone. Thus, the sources of petroleum pollution are presented, the paths of migration to the monument, the physical phenomena concerning the entrance of such pollution into the pores of the stone, as well as its potential movement in the porous net. The main effort was to assess the protection of a monument subjected to chronic petroleum pollution, by reducing the pollutant content of the stone. The existing methodologies on the reduction of hydrocarbon content in soil and groundwater were assessed, and criteria were set for a remediation method applicable to the treatment of the foundations of stone monuments. The method identified as most appropriate was bioventing, which is the use of air to stimulate indigenous microorganisms that have the ability to transform petroleum hydrocarbons into harmless by-products. Three types of limestone (grey-, marly-, and sandy-) were shown to be significantly weakened by a non-immiscible mixture of water and petroleum hydrocarbons when present in the pores of the stone. The bioventing treatment was shown to reduce the hydrocarbon content of the stone by 75% after a 60 day treatment. The rate of biodegradation achieved was 30 times higher than when no treatment was administered. Recommendations on future management and conservation policies of stone monuments are given.

The purpose of this study is to characterize the water chemistry of Lake Gregory in Crestline, California. The collection of water samples occurred a short time after the end of the summer recreational season in the late fall. Several chemical parameters were measured in an effort to determine the overall water quality during this time.

Orientador: Altair Benedito Moreira / Coorientador: César Ricardo Teixeira Tarley / Banca: Diogo Paschoaline / Banca: Ana Cristi Basile Dias / Resumo: / Abstract: / Mestre

RNA interference has enormous potential as a potent, specific, and environmentally friendly alternative to small molecule pesticides for crop protection. The use of exogenous double-stranded RNA offers flexibility in targeting and use in crops in which transgenic manipulation is not an option. The combination of RNAi with nanotechnology offers further advantages that are not available with dsRNA alone. In this work, I have evaluated several different combinations of nanomaterials and polymers for use in RNAi-based pest control systems. First, I have characterized the use of chitosan/dsRNA polyplex nanoparticles for gene knockdown using the model nematode Caenorhabditis elegans. Though chitosan/dsRNA polyplexes are equally as effective as naked dsRNA for gene knockdown on a concentration basis, these materials are assimilated into cells in a manner independent of dsRNA specific transport proteins. The mechanism of uptake is likely clathrin-mediated endocytosis. In addition, I identify a significant and yet unreported side-effect associated with chitosan exposure, the dysregulation of a major myosin isoform. Next, I have determined the efficacy of chitosan/dsRNA polyplex nanoparticles under different environmental conditions. The presence of inorganic ions (phosphate and nitrate) at realistic environmental concentrations does not alter the efficacy of the nanoparticles for gene knockdown, nor do they inhibit knockdown by naked dsRNA. These conditions did not cause any significant changes to the hydrodynamic diameter or zeta potential of the particles themselves between treatments. By contrast, a pH higher than six and the presence of natural organic matter significantly reduce the efficacy of the nanomaterials at gene knockdown but leave knockdown by naked dsRNA unaffected. Though some changes in polyplex size are observed in the pH treatments, these changes are comparatively small, and particles remain well within the size that can be ingested by C. elegans. At pH 8, the charge of the particles is effectively neutral. Similarly, concentrations of natural organic matter >2.5 mg/L cause a charge reversal of the particles, from strongly cationic to strongly anionic. Large aggregates are also visible in each of these treatments. Lastly, I characterize the efficacy of a suite of different polymer and solid core nanomaterials for dsRNA delivery, similar to the above. Poly-L-lysine, poly-L-arginine, Ge-doped imogolite, and poly-L-arginine-citrate coated Au nanoparticles all fail to cause any appreciable knockdown in the same C. elegans reporter system. Uptake of the polymers was exceedingly poor, and though the Au particles appear to have been ingested, there is no evidence of significant gene knockdown. Furthermore, poly-L-arginine caused significant injury to the mouthparts of C. elegans exposed to these materials. Layered double-hydroxide nanoparticles were successful at gene knockdown, and appear to function slightly better than naked dsRNA alone, and were translocated in C. elegans in a similar fashion to naked dsRNA. Taken together, these findings aid in the development of safe and effective RNAi biological control agents.

Exposomics is an emerging area of study that looks at how the environment around a person or persons affects their overall health. Biomarkers have emerged as useful tools to better understand how the exposome affects a person. In this work, we investigate two potential endogenous biomarkers, homocysteine and glutathione that have been previously implicated in a number of diseases that have been linked to environmental causes. We also investigated an environmental exposure, the fungicide Ziram, which epidemiologically has been linked to diseases. In our investigation, we utilized capillary electrophoresis and capillary electrophoresis-mass spectrometry to develop a method for homocysteine and identify a derivative to keep it from auto-oxidizing. We utilized mass spectrometry to identify the best ionization technique to detect Ziram and confirmation of where it binds on thiol-containing molecules. We also developed a method to extract glutathione-Ziram from serum and utilized liquid chromatography-mass spectrometry to begin a validation of glutathione-Ziram. Although future work is needed, we believe that this work was the beginning steps to understand biomarkers and their role in the exposome.

Superacidic mesoporous materials containing covalently embedded PTA were synthesized by sol-gel method. Tetraethyl orthosilicate (TEOS) and phosphotungstic acid (PTA) were used as precursors in the synthesis, ionic and nonionic surfactants were used as pore-forming agents, the reaction proceeded in acidic media. TEM images revealed mesoporous structure with embedded PTA clusters. FT-IR spectra of obtained materials contained characteristic bands of PTA at 957 cm-1. Synthesized catalysts had high BET surface area and high concentration of acidic sites. Alkylation of 1,3,5-trimethylbenzene by 1-decene demonstrated high catalytic activity. The catalyst obtained with Pluronic P123 as a template was the most effective and resulted in highest conversion of 1-decene into alkylated products. Covalent embedding of PTA clusters in addition to thermal and chemical stability of synthesized catalysts enabled their recyclability. Catalysts remained active during subsequent cycles of alkylation.

This research focused on the use of nanoscale zero-valent iron (NZVI) to remediate trinitrotoluene (TNT). Zero-valent iron has demonstrated effective degradation of TNT, however, these particles themselves have significant problems in treating sorbed phase TNT in the aerobic environment. This research was comprised of four areas: degradation studies of neat nano-iron with aqueous TNT, degradation studies of nanoiron emulsion with aqueous TNT, characterization of TNT in Vieques, Puerto Rico sediment, and Solid Phase Microextraction (SPME) technique interface with HPLC. Both neat and emulsion NZVI studies showed TNT degradation. More degradation was seen in studies using fresher iron. The results from our characterization study in Vieques, PR showed no presence of TNT within our detection limits of 0.0625ppm. Also, SPME is a new extraction solvent saving technique being explored because of its reproducible extractions in water. This work also gives a brief history of SPME and possible uses with TNT.