Browsing by Subject "oil and gas"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Impacts of Oil and Gas Development on Wintering Grassland Birds at Padre Island National Seashore, Texas(2010-10-12) Lawson, Ardath L.Padre Island National Seashore provides important habitat for wintering grassland birds, which are declining throughout their breeding range, yet oil and gas development is widespread in the park. My objective was to evaluate the effects of resource extraction on the park's grassland birds and make management recommendations based on my findings. In January-March 2007 and 2008, I surveyed 5 active, 4 abandoned, and 4 road sites to investigate the relationship between distance from disturbance (well pads, access roads) and bird abundance. I also compared abundance among the 3 site types. At each site I recorded bird numbers and species in 10-m distance bands along all transects (4 transects/well, 2 transects/road), each extending 300 m from the road or pad. At road sites bird abundance was positively correlated with increased distance from road edge, but I found no linear relationship at active or abandoned well sites. However, mean bird abundance in the first (0-30-m) distance interval of active well transects was less than half that at the second interval, and was the lowest value for all active intervals except the ninth. First-interval abundance at active wells was lower than abundance at any abandoned well interval. Road transects likewise showed low abundance in the initial interval, although unlike at active wells abundance increased steadily with distance from the center of disturbance. This trend of lower overall numbers at the first interval of active well transects was driven largely by 1 species, the meadowlark. A combination of high noise levels near active well pads (up to 80 dB) and lack of tall vegetation (on average 30% lower than the 60-90-m interval) from which to sing may have contributed to low numbers of meadowlarks, which were the only birds to sing regularly during my study period. While most birds appear to be minimally affected by resource extraction at Padre Island, to ensure minimal impacts on sensitive species I recommend: 1) reducing noise at active sites, 2) limiting disturbance to vegetation near pads and roads, 3) maintaining existing perch sites, 4) restoring all vegetation to its pre-extraction condition, 5) limiting road construction.Item Reactive Transport Modeling of Natural Attenuation in Stormwater Bioretention Cells and Under Land Application of Wastewater(2014-04-29) Zhang, JingqiuNatural attenuation is a cost effective method to treat wastewater applied into soil. The natural attenuation process includes diffusion, dispersion, microbial activity, oxidation, mineral precipitation, sorption, and ion exchange to mitigate hydrocarbon, nutrient, metals, and solids. Vegetation also plays an important role in reducing water volume, and removing nutrients and solutes from the contaminated soil. We used a reactive transport model MIN3P-THM to simulate the natural attenuation on stormwater runoff, and oil and gas produced wastewater. In bioretention systems, the model results indicated that the bioretention systems were able to remove most of heavy metals, nitrate, and organic carbon through natural attenuation in the soil. Due to macropores and fast flow paths created by roots in vegetated cells, the water can carry ions flowing out of the system very quickly leading to a higher outflow rate and less removal efficiency than non-vegetated cells. The model also tested a range of possible design configurations to determine the optimal saturated zone thickness and outlet location for nitrate removal. In addition, different rainfall levels did influence the natural attenuation performance of bioretention cells under long time application. Due to less water and chemical input, climate patterns may lead to better removal of heavy metals. For land application of Oil and Gas Exploration and Production wastewater, five scenarios were developed to study the impact of chloride, salts, and organic matters on natural attenuation. Water and salinity stress were considered in the model to deal with high salinity wastewater in the root zone. For High-FDS and High-Cl treatments, long time application of high salinity wastewater did accumulate salts in the root zone and affect groundwater quality. Under the High-TOC treatment, TOC begins to build up in the root zone in concentrations up to 750 mg/L. More attention should be paid on long-term land application of high salinity wastewater; the application process may pollute groundwater and nearby rivers causing human health hazard. Plants would reduce water uptake to survive themselves when water and solute stress occurred under high salinity conditions.