The Brahmaputra River has constructed an upland fluvial fan delta with an estimated volume of >5 million km^3; of riverine sediments. Much of this stratigraphy was generated during the Quaternary, a period of time characterized globally by cyclic glacioeustatic fluctuations and regionally by ongoing deformation of the Bengal basin associated with Himalayan convergence. This research examines the extent to which these external climatic and tectonic conditions have influenced the paleogeography of the river and the evolution of the basin. Stratigraphic analysis of sediments constructed by the Brahmaputra reveals that the course of the river has evolved in direct response to uplift of the Shillong Plateau, a regional crust block associated with a forward jump of the Himalayan arc. Specifically, the river has been episodically deflected by uplifting terrain and subsequently attracted to topographic subsidence below the overriding thrust, resulting in the anfractuous course that the river follows today. Overprinted upon this tectonic steering of the river, episodic paleohydrological events in the form of ice-dam floods were instrumental in scouring a wide valley paved by the deposition of cobble to boulder-sized gravel during the late glacial to interglacial transition. Presently, the river braidbelt is constrained within this flood-generated paleovalley, reflecting the long-term influence of paleohydrological events that occurred more than 10,000 years ago on the modern course of the river. Importantly, these findings suggest that allogenic influences played a major role in the morphostratigraphic evolution of one of the worldâs largest fluvial systems.

<p> Landmines are one of the most prolific, human-made environmental hazards impacting the world. Although there are numerous technologies used to detect buried landmines, none enable a perfect find rate, in part, due to the heterogeneous nature of the environment in which they are buried. Variations in environmental conditions such as soil moisture and climate (e.g., temperature, diurnal fluctuations) impact detection performance. Improved understanding of the environmental conditions associated with minefield emplacement is needed to enable improvement in the algorithms used by detection technologies (e.g., infrared, ground penetrating radar), thus increasing their performance and probability of detection rates. However, there is a lack of understanding of the effect of the mine placement on the heat and mass transfer dynamics in the vicinity of the mine. More specifically, very little is known about how soil disturbance, a process that changes the soil thermal and hydraulic properties of the soil surrounding the mine, due to the placement and burial of the mine effects the soil moisture and temperature conditions in the vicinity of the mine. This is important because understanding these impacts enables increased ability to compare progressively complex models to measured aspects of interest specific to landmine emplacement conditions. The purpose of this research is to better understand the effect of soil disturbance (i.e., loosening the soil) and mixing (i.e., combining different soil types) on heat and mass transfer behavior in the vicinity of buried landmines. The aim is that this knowledge can help future research efforts to improve algorithms associated with various detection technologies. This research integrates a field experiment and numerous laboratory experiments with analytical modeling. In the first task, the thermal conductivity of mixed sands are evaluated at the small scale, providing critical knowledge of the unique behavior. Results indicate that for the test sands studied, knowledge of soil density enables identification of both saturated and dry thermal conductivity which enhances modeling of the thermal conductivity-saturation relationships. Experimental data were used to test thermal conductivity-saturation models. The analytical models varied in their ability to capture the thermal behavior, demonstrating the need for a physically based thermal conductivity-saturation model. The second task compares several approaches used to determine evaporation with several laboratory evaporation and evapotranspiration experiments in an effort to determine an appropriate method that can be applied to studies of landmine detection, specifically, disturbed soil conditions. Results demonstrate that the methods vary in their ability to capture atmospheric versus diffusion dominated evaporative stages for the test soils and boundary conditions studied. Although no one method is applicable for all boundary and initial conditions, the sensible heat balance and heat pulse method enabled the highest level of agreement between measured and modeled evaporation from bare soil experiments. Additionally, the ability of this method to isolate evaporation under evapotranspiration conditions has the potential to isolate transpiration which is significant for many agricultural applications as well as modeling efforts. The third task investigates the impact of soil disturbance and mixing on heat and mass transfer behavior under varying climate conditions at the laboratory scale. Using the methods established in Task 2, I could quantitatively understand the evaporation rates from soils under different conditions (e.g. disturbed or loose conditions compared to undisturbed or tight conditions) using both in-situ and remotely sensed temperature and soil moisture data. Results demonstrate that the disturbance and mixing cause a significant increase in evaporation compared to undisturbed soil conditions. Under disturbed conditions without mixing, the increase evaporation occurred in part to due capillary pumping from the loose soil into the tight soil. Additionally, higher evaporation rates were observed from the upstream tight region compared to the downstream tight region. Finally, the fourth task is a field scale proof of concept demonstration. The purpose of this task is to obtain a data set that includes aspects of tasks 1-3, thus testing our understanding of soil disturbance at the field scale. Experimental results demonstrate distinct behaviors in soil moisture and temperature distributions above and around buried objects that change with climate forcings (i.e., temperature and rain events).</p>

Arsenic has been used throughout recorded history but during the industrial revolution widespread use led to global environmental impact. The two forms that should be considered in environment management are arsenate and arsenite. The calculations of environmental risk for arsenic exposure relies the toxicity of arsenite however, in well aeriated surface soils arsenate may be the predominate form. Ecological risk assessments based on arsenite studies will lead to restrictive remediation requirements that do not adequately reflect the level of risk. Arsenate resembles phosphate and as such has a greater affinity for phytoremediation. Phytoremediation is one of the most viable and cost effective cleanup techniques developed. Different mathematical approaches have been implemented to characterize phytoremediation systems to address concerns with performance. A system dynamic model is presented to describe solute transport in groundwater coupled to sorption by plant roots, translocation into plant stems, and evapotranspiration. The model was tested and assessed using published and peer-reviewed experimental data, to assess its capability to mimic phytoremediation processes. The model is consistent with previous research establishing the extraction process as a constringent factor for this cleanup technique. The model included modules that can estimate rainfall, seasonal temperature and growth. The modules allow for the independent verification of data before input into the model. The implementation of phytoremediation model can provide information about: pollutant-media-plant interaction, pollutant concentration and flow rate through the plant.

<p>Research into the age, growth, and reproductive characteristics of chondrichthyan fishes has increased substantially over the past couple of decades. This study set out to estimate age deepsea skate, <i>Bathyraja abyssicola</i> using vertebral centra and caudal thorns, estimate length at age, and determine length at maturity. Sixty-three specimens of <i>B. abyssicola</i> (n=29 males; n=34 females) were taken on National Marine Fisheries Service bottom trawl surveys between 2001 and 2012. Information derived and structures collected from these samples included sex, maturity class, total length, caudal thorns and, vertebrae. Ageing methods attempted include histology and gross sectioning (vertebral centra) and surface staining (caudal thorns). Moderate success with centra sectioned using the histological method allowed some inference to be made into life history characteristics. Deepsea skates appear to have slow average growth (26 mm yr^-1 &plusmn;5.41, 95% c.i.) and mature at a large size (males: TL₅₀ = 1175.4 mm, females: TL₅₀ = 1267.3 mm). Band pair counts were not validated as true ages. Males from which growth bands could be enumerated were smaller (<i>n</i> = 10, x&macr; = 718 mm, SD = 209 mm) on average than that for females (n = 7, x&macr;=990 mm, SD = 319 mm). This study provides the first attempt to assess <i>abyssicola</i> age, growth rate, and sexual maturity traits; information needed for informed skate management.</p>

The fungicide 2,6-dichloro-4-nitroaniline (DCNA) is applied to crops grown in areas near both freshwater and saltwater bodies and it can enter the surface waters where it is susceptible to photolysis; limited information is published on the photodegradation of DCNA. It has been shown that the salinity of seawater can influence both the overall rate of degradation of chemicals and impact the distribution and types of photoproducts generated during the photodegradation processes of a pesticide. The photodegradation of DCNA was measured in distilled water, artificial seawater, estuarine water, and phosphate buffer to determine the degree of differences in the degradation rate in various matrices. The brominated analogue 2,6-dibromo-4-nitroaniline (DBNA) was measured identically to determine the impacts of other halogens on the degradation process. Solutions of DCNA and DBNA at a concentration of 1 ppm were prepared and irradiated for 24 hours in an Atlas SUNTEST XXL+ photochamber that mimics the wavelength distribution and intensity of sunlight. Dark controls were run simultaneously. Samples were withdrawn at 0, 2, 4, 6, 12, and 24 hours and analyzed for residual DCNA or DBNA using an Agilent 1260 Infinity High Performance Liquid Chromatograph. The formation of ions such as nitrate, nitrite, bromide, and chloride were measured using a Thermo Dionex ICS-5000+ Ion Chromatograph. The half-life of DCNA in distilled water was calculated to be 7.62 ± 0.094 hours and 7.37 ± 0.279 hours in artificial seawater; statistically there was no significant difference in the degradation rate through the first half-life. Analysis of the quick formation of nitrite and chloride ions, and later formation of nitrate ions, suggests photonucleophilic substitution processes are occurring as the compound is degrading, followed by further degradation of nitrite to nitrate likely also due to photolysis processes. Small aliphatic acids, maleic and fumaric acid, were detected after 12 hours of irradiation by HPLC indicating degradation of the aromatic ring structure. Differences in formation rate and decline for intermediate photoproducts were observed in seawater and distilled water suggesting salinity affects the rate of formation of this photoproduct.

Coastal Louisiana, the seventh largest delta on earth, is one of the most vulnerable coastal areas in the United States of America (USA) because of its land loss problem. Coastal land loss is usually caused by many complicated factors. With the rapid increase in human activities, more studies on land loss have focused on the anthropogenic elements, but less on the pattern of the landscape. It is expected that the type of spatial arrangement, such as high degree of fragmentation, would affect the degree of land erosion. A quantitative evaluation of coastal landscape fragmentation and its influences on land loss would help coastal protection. The purpose of this research is to study the effects of landscape fragmentation on land loss in the Lower Mississippi River Basin (LMRB) region. The main scientific question addressed in this study is: does the degree of fragmentation influence the degree of coastal land loss? This thesis applied fractal analysis and spatial autocorrelation statistics to calculate the degree of fragmentation, using Landsat-TM land cover data in 1996 and 2010 with a pixel size of 30m * 30m. First, 100 samples of a 50-percent land-water ratio for each of the three box sizes 101*101, 51*51, and 31*31 pixels were extracted from the study area. Linear regressions were conducted to compute the relationship between fragmentation and land loss. The hypothesis is that the higher the degree of spatial fragmentation, the greater the degree of land loss. The results show that boxes with a higher degree of fragmentation had more land loss for box sizes of 51*51 and 31*31 with p-values less than 0.001. The relationship is not significant for 101*101 with p-values greater than 0.05. Thus, land fragmentation is a worthy element to be considered as a land loss factor. These results should be useful to the development of better strategies to strengthen the protection of a highly fragmented coast.

The purpose of this study was to test a model of conservation behavior in a Mexican community. Reuse and recycling patterns of one-hundred families in a middle-sized city of Northwestern Mexico were analyzed using direct observations of reused and recycled items. Predictors of the studied behaviors were assessed by an inventory administered to housewives, which included self-reports, observations and event-test activities of dispositional variables (motives, competencies, beliefs, knowledge), demographic factors (age, income, education) and situational variables (storage facilities, presence of collectors of recyclables, use of radio, TV, newspapers and books). A comparison of responses to self-reports and observations of reused/recycled items showed a significant lack of correspondence between these measures. Therefore, observation was selected as the method best indicating reuse and recycling. These observations revealed that reuse is a more generalized conservation practice, while recycling is limited to selected items. Multiple regressions of dispositional, demographic and situational variables on both conservation behaviors showed that motives to reuse was the only significant direct predictor of reusing, while motives to recycling predicted recycling in a positive way, and facilities for storage had a significant but negative effect on recycling. However, the use of a structural equations models revealed the presence of significant indirect predictors of most of these variables on reuse and recycling. Motives and competencies to reuse/recycle positively affected conservation behaviors, but conservation beliefs did not; Competencies had a positive influence on motives to reuse and recycle, and the use of TV/radio negatively affected the motivation to reuse. Knowledge of reusables/recyclables had a positive effect on competencies, while reading books and newspapers had a significant influence on knowledge about reusables. The indirect effect of education on these conservation behaviors was manifested through its significant positive influence on reading books/newspapers and a significant negative effect on the use of radio and television. The presence of people collecting recyclables did not affect housewive's recycling while the possession of storage facilities negatively affected such a recycling practice.

No description available.

No description available.

This research focused on the effects of un-weathered Macondo crude oil on the growth rates and pigment ratios of phytoplankton isolated from Grand Isle, LA. The experiments involved incubating nutrient-enriched artificial media containing a range of oil concentrations up to 19.2 ppm with small aliquots of coastal water from Grand Isle and measuring the growth rates of the phytoplankton during the subsequent 1014 days and the pigment ratios of the phytoplankton at the end of log-phase growth to determine whether the crude oil affected the growth rate of the phytoplankton and their composition in terms of pigment ratios. Pigment analysis revealed that the cultures consisted almost entirely of diatoms. Results showed that there was a significant effect on diatom growth rates from the concentration of crude oil, the month, and the interaction between oil concentrations and months. In March, April, and May, growth rates at oil concentrations from 0.1 to 0.6 ppm were about 10% higher than controls. At higher oil concentrations there was a negative correlation between oil concentrations and growth rates. The ratio of fucoxanthin to chlorophyll a was positively correlated with oil concentrations in February, March and April, the implication being that the size of the diatom photosynthetic units changed in response to the oil. There was no significant correlation between growth rates and oil concentrations in July and August, nor was there any correlation between pigment ratios and oil concentrations. The July and August phytoplankton grew roughly twice as fast as the March, and April control cultures, although the growth conditions were identical. Analysis with a mathematical model of phytoplankton growth suggested that in the presence of oil, there was a transfer of resources within the March, April, and May phytoplankton, the result being an increase in the size of their photosynthetic units and a decrease in the number of photosynthetic units in response to the presence of oil. The principal antenna pigment was fucoxanthin. The phytoplankton isolated in July and August, in contrast, appeared to be completely unaffected by the presence of oil up to a concentration of 19.2ppm.