Digital Commons Network^™

Development Of Micro-Scale And Automated Membrane Extraction Systems For Water Analysis, Xiaoyan Wang

Dissertations

Monitoring of trace level contaminants in water involves the extraction and enrichment of analytes. Over the years several techniques have been developed for this purpose. Currently there is an urgent need for the development of micro-scale extraction techniques that can lead to simple, fast trace analysis. Automated instruments that can be used for continuous, on-line analysis are also important. Membrane extraction can address both these needs, because it can be carried out in a continuous fashion and can also be miniaturized. This research addresses these two aspects of membrane extraction for the next generation of sample preparation.

Micro-Scale Membrane Extraction: …

Effect Of Heavy Metals On Salt March Biota, Kallaya Suntornvongsagul

Dissertations

Environmental restoration of disturbed, degraded and potentially contaminated wetland sites aims for the persistent and sustainable re-establishment of biological communities and important wetland functions. An ecologically informed restoration strategy presupposes some understanding of these system processes, but also of potential impacts on contaminants in the environment for risk assessment, long-term management, and potential cost-effective mitigative measures. In this study, potential effects of moderate heavy metal contamination in sediments of the urban salt marsh Harrier Meadow, NJ, were evaluated on growth performance of the common salt marsh plant S. patens and associated arbuscular mycorrhizal fungi (AMF) colonizing its roots. Growth performance …

Evaluating Rhizodegradation Of Petroleum Hydrocarbons And Polycyclic Aromatic Hydrocarbons In Wetland Sediments Containing Spartina Patens, Robert J. Lippencott

Dissertations

Biodegradation of petroleum hydrocarbons (PHC) and 16 polycyclic aromatic hydrocarbon (PAH) compounds was evaluated in sediments from a stormwater basin that was a former salt marsh at an active oil refinery. Spartina patens were grown in basin sediments during a field study and a greenhouse study over three consecutive growing seasons. Ninety percent (90%) survival was observed in field study plots containing sediments with <12% PHC. In the greenhouse study, planted and bulk sediments were monitored for PHC, PAH, microbial density, nutrients, pH, redox and root biomass at 2.5 and 7.5 cm in sediments with <12% PHC. The sediments contained on average 6.5% to 9.5% PHC and 56 to 124 parts per million (ppm) total PAH. The plants exhibited a 95% survival rate and added from 1% to 2% root biomass to the sediment. Microbial densities in planted sediments were significantly higher than in bulk sediments (p<0.05). Oxidizing conditions were prevalent in all treatments at both depths; however, reducing conditions developed in the planted sediments at 7.5 cm. PHC was 35% to 37% lower in the planted sediments vs. bulk sediment at the end of the study. Planted sediment PAH concentrations were generally lower than in bulk sediments. Low MW PAHs (2 and 3-Rings) were either absent or at relatively low concentrations in all treatments. Phenanthrene concentrations in bulk sediments did not change, but were reduced by 95% in planted sediments (p<0.01), with half-life estimates of 141 to 165 days at 2.5 cm. Temporal changes in high MW PAHs ( 4-Rings) were not observed over the greenhouse study period. Differences in PAH concentrations between planted and bulk sediments exhibited a decreasing trend with PAH molecular weight. Evaluation of differences in planted and bulk sediment PAH concentrations suggests that lower MW PAHs degrade better under oxidizing conditions, and higher MW PAHs under reducing conditions in the planted sediments. Comparison of planted and bulk sediment PAH concentrations links depth and redox conditions to decreases in PAH as a function of PAH MW. Therefore, it was concluded that spatio-temporal variations and cycling of redox conditions should be considered to properly evaluate biodegradation of PAH.

The Testing Of Semiconductor-Based Adsorption Modified Photosensitive Sensors For Their Response To A Volatile Organic Compound, Oxygen, Humidity, And Heating, Roberta Rosty

Dissertations

Two thin-film sensors, composed of different thicknesses (approximately 0.5 microns and 4.5 microns) of a cadmium sulfide layer coated with Rhodamine B fluorescent dye on a glass substrate, were tested for change in photoconductivity due to exposure to different concentrations of gaseous organic molecules in the parts-per-million (ppm) range.

It was theorized that the gaseous organic molecules would adsorb to the dyed semiconductor surface and that some energy would be transferred to the adsorbed analyte rather than to the cadmium sulfide semiconductor layer through the dye, thereby decreasing the photoconductivity of the surface in an amount proportional to the analyte …