South Louisiana Research Articles

Denitrification in a South Louisiana wetland forest receiving treated sewage effluent

Although denitrification has the potential to reduce nitrate (NO3−) pollution of surface waters, the quantification of denitrification rates is complex because it requires differentiation from other mechanisms and is highly variable in both space and time. This study first measured potential denitrification rates at a wetland forest site in south Louisiana before receipt of secondary wastewater effluent, and then, following 30 months of effluent application, landscape gradients of dissolved nitrate (NO3−) and nitrous oxide (N2O) were measured. A computer model was developed to quantify N transformations. Floodwater NO3− and N2O concentrations were higher in the forest receiving effluent than in the adjacent control forest. Denitrification rates of NO3−-amended soil cores ranged from 0.03–0.45 g N m−2 d−1 with an overall mean of 0.10 g N m−2 d−1. Effluent N is being applied at a rate of approximately 0.034 g N m−2 d−1, with approximately 95% disappearing along a 1 km transect. In the treatment forest, floodwater NO3− concentrations decreased from 1000 μM at the inflow point to 50 μM along the 1 km transect. Nitrous oxide concentrations increased from 0.25 μM to 1.2 μM within the first 100 m, but decreased to 0.1 μM over the next 900 m. The initial increase in N2O was presumably a result ofin situ denitrification. Model analyses indicated that denitrification was directly associated with nitrification and was limited by the availability of NO3− produced by nitrification. Due to different redox potential optima, coupling of nitrification and denitrification was a function of a balance of environmental conditions that was moderately favorable to both processes. N removal efficiency was largely dependent on the proportion of effluent NH4+ to NO3−. When NH4+/NO3− was ≤1, average N removal efficiency ranged from 95–100%, but ratios that were >1 reduced average efficiencies to as low as 57%. Actual effluent NH4+/NO3− loading ratios at this site are approximately 0.2 and are consistently <1.

153 Indoor allergen loads in homes in South Louisiana

153 Indoor allergen loads in homes in South Louisiana

Evaluation of Wetland Gain and Loss of Abandoned Agricultural Impoundments in South Louisiana, 1978–1988

AbstractAt least 43 agriculture fields were built in south Louisiana wetlands between 1900 and 1920 using pumps and levees. All but one project is now abandoned as a result of soil subsidence, financial difficulties, or multiple levee failures. Some are now in flood‐protected urban zones, and the remainder are mostly open water. The total area of abandoned agricultural fields in 1990 is large (&gt; 80,000 ha), and their levees continue to deteriorate naturally. Ten failed or abandoned coastal agricultural impoundments (22,680 ha) were examined to determine recent wetland restoration or regression rates from 1978 to 1988. Wetland area and levee length were determined from aerial photography for 1978,1983,1985, and 1988. Average wetland change rates for all areas ranged from −4.28 to +2.54% per year from 1978 to 1988. One site gained wetland area between 1978 and 1988 (77 ha/yr), and four sites gained wetland area between 1985 and 1988 (range 14–439 ha/yr). Wetland area in the other sites either remained stable or declined during the study period. The results from a multiple regression model indicate that restoration is inversely related to impoundment size and directly related to levee reduction. Results from a multiple regression model indicate that active levee removal will probably enhance wetland restoration rates at a very favorable cost (&lt; $1/ha) and will be sustainable with little additional management.

Subsurface geology of Louisiana hazardous waste landfills: A case study

Many hazardous waste sites in the south Louisiana Gulf Coast have been emplaced in sediments of Plio-Pleistocene to Recent age. Because of the fining upward nature of these regressive-transgressive fluvial-deltaic sequences and the purported confining capabilities of the shallow clay layers within them, this area would seem to be ideal for the location of surface waste landfills. However, detailed geologic mapping at a site in southeastern Louisiana documents how the three-dimensional distribution of sediment types and early diagenetic features, both of which were ultimately controlled by depositional history, can increase effective vertical permeability of finegrained sequences. Many bodies of sand that appear to be isolated in standard geotechnical cross sections can be shown to be part of spatially complex three-dimensional distributary networks, with fine-grained sediments representing overbank and backswamp deposits. Some clay layers are actually a composite of thinner clay beds, each subjected to subaerial exposure and the development of secondary porosity related to soil formation. There has been documented leakage of wastes down through the clays, and a recent study indicates that the effective vertical hydraulic conductivity of the clay layers exceeds 10−5 cm s−1, or from one to four orders of magnitude higher than values measured on samples from cores of the same sediment. An understanding of the depositional framework, facies architecture, and diagenetic history of geologic materials underlying waste disposal sites in Louisiana is required for rational development of monitoring and remediation plans.

Determinants of Participation and Consumption: The Case of Crawfish in South Louisiana

AbstractThis study investigates the determinants of crawfish consumption in South Louisiana using a generalized limited dependent variable model that accounts for both participation and consumption decisions. Income, Catholic, white, and household size increase the likelihood of crawfish consumption but not the conditional level of consumption. Education and employment status are among the other household characteristics that determine the conditional level of consumption.

Arcuate and growth faults in basin models, with an application to a south Louisiana roll-over structure

Using a two-dimensional fluid-flow/compaction code an investigation is given of the influence of dynamically evolving curved faults in impacting the overpressure development of a sedimentary basin. Four synthetic cases are examined: an homogeneous sandy-shale section, and a mixed layered section of sand and shale, with fault conditions investigated being open to fluid flow, and closed to fluid-flow, respectively. Fault throws can be instantaneous either in time (such as a gravity slump) or can be progressive in time (such as a growth fault). A case history from south Louisiana also is examined to illustrate typical response patterns.

Critical reflections on the fiction of Ernest J. Gaines

These essays examine the themes and techniques in the work of the African-American writer Ernest Gaines. Because his work is so deeply rooted in his native south Louisiana, many of the essays explore the relationships between Gaines's writing and the culture of the area.

Physiologic and clinicopathologic effects of crude oil on loggerhead sea turtles

The physiologic and clinicopathologic effects of weathered South Louisiana crude oil exposure were studied in the laboratory in juvenile loggerhead sea turtles. Sea turtles ingested oil incidentally, and oil was observed clinging to the nares, eyes, and upper esophagus, and was found in the feces. Oiled turtles had up to a four-fold increase in white blood cell counts, a 50% reduction in red blood cell counts, and red blood cell polychromasia. Most serum blood chemistries (e.g., BUN, protein) were within normal ranges, although glucose returned more slowly to baseline values than in the controls. Gross and histologic changes were present in the skin and mucosal surfaces of oiled turtles, including acute inflammatory cell infiltrates, dysplasia of epidermal epithelium, and a loss of cellular architectural organization of hte skin layers. The cellular changes in the epidermis are of particular concern because they may increase susceptibility to infection. Although many of the observed physiological insults resolved with a 21-day recovery period, the long-term biological effects of oil on sea turtles remain completely unknown.

An Exposure-Based Analysis of Property-Liability Insurer Stock Values around Hurricane Andrew

Introduction Investors hold a set of information that generates expectations concerning risk and earnings. In an efficient market, stock prices quickly reflect all of the relevant information involving a firm. Several studies have examined the type of information investors consider relevant for pricing decisions. Dividend and earnings announcements and stock splits have been extensively covered (Charest, 1978; Aharony and Swary, 1980; Asquith and Mullins, 1983). Other studies have addressed the impact of losses on firm value. Sprecher and Pertl (1983) and Davidson, Chandy, and Cross (1987) found a negative relationship between large losses and firm value. Reilly and Drzycimski (1973) found that stock prices adjust immediately following the announcement of major world events. Shelor, Anderson, and Cross (1990) examined the effect of the October 17, 1989, California earthquake on the stock value of firms in the real estate industry. They concluded that the earthquake conveyed important new information to the market that was reflected in significant negative stock returns among real estate firms operating around San Francisco (the area sustaining the most damage from the earthquake). Real estate-related firms operating in other areas of California were generally unaffected by the earthquake. The occurrence and timing of the earthquake could not be anticipated and, thus, instantaneously introduced new and relevant information to the marketplace. The large negative returns for the sample indicated that investors viewed the earthquake as a signal of unfavorable financial conditions for the real estate industry in the San Francisco bay area. The market response to the earthquake among other California firms was consistent with that observed for an event that has no impact on market valuation. These results provide evidence that the market may discriminate among firms in relation to their geographic risk exposure. Such behavior is expected in a rational and efficient market. In a related article, Shelor, Anderson, and Cross (1992) examined the market response of property-liability insurers around the earthquake. In contrast with the real estate-related firms, the property-liability industry demonstrated a significant positive response to the earthquake, indicating that investor expectations of higher demand for insurance (positive effect) may have more than offset the potential earthquake losses (negative effect). Aiuppa, Carney, and Krueger (1993) also explored the impact of the earthquake on property-liability stock values and found a similar positive response. These results suggest that the two industries were affected by the earthquake in different ways; that is, the California earthquake stimulated industry-specific responses. This conclusion, in part, provides the motivation for this study involving the examination of the effect of Hurricane Andrew on property-liability stock values. Research Question In August 1992, Hurricane Andrew struck South Florida and Louisiana with sustained winds of 138 miles per hour. The magnitude of this storm's devastation made it the costliest natural disaster in U.S. history. The property-liability insurance industry estimates that Andrew caused more than $20 billion in property damage.(1) This dwarfs the $7 billion in claims paid after Hurricane Hugo (the previous costliest natural disaster) struck North Carolina and South Carolina in September 1989. The effect of catastrophic property damage on the value of property-liability insurers is the subject of this study; specifically, does the market demonstrate an ability to discriminate by the degree of loss exposure of property-liability insurers around significant hurricanes (such as Andrew)? Although some insurers have heavy loss exposure in certain geographic areas of the country, other firms have little or no business in the affected areas. If the market is rational and efficient, then it would be surprising to find that unexposed or lightly-exposed firms experience a similar hurricane-induced market reaction to that of heavily-exposed firms. …

THE DEVELOPMENT OF BIOREMEDIATION FOR OIL SPILL CLEANUP IN COASTAL WETLANDS: PRODUCT IMPACTS AND BIOREMEDIATION POTENTIAL

ABSTRACT Although bioremediation for oil spill cleanup has received considerable attention in recent years, its satisfactory use in the cleanup of oil spills in the wetland environment is still questionable and generally untested. We have initiated a multidisciplinary experimental program to evaluate the use of both microbial seeding and fertilizer as means of enhancing oil biodegradation in coastal salt marshes. We are utilizing controlled greenhouse experiments as well as field trials to test the efficacy and ecological safety of these enhanced biodegradation methodologies. This paper summarizes the overall scope of the study and presents some preliminary findings concerning marsh plant response to the bioremediation agents. We shall report on the results of the first year of this three-year investigation. Sods of marsh (soil and vegetation intact), approximately 30 cm in diameter and 25 cm deep, collected from the inland zone of a Spartina alterniflora dominated salt marsh in south Louisiana were used in a greenhouse experiment to identify the effects on plant and soil responses of the following treatments, with and without oil: seeding product, fertilizer product, and control (no product). Mesocosms were sampled for petroleum hydrocarbon chemistry to identify and quantify the degree of oil biodegradation, soil microbial response to determine the effect of the bioremediation products on the microbial communities that are performing the oil biodegradation, soil chemistry to determine the effect of the bioremediation products (such as nutrients, soil reducing conditions, and soil toxins) on those factors that limit the growth of microbes and plants, and plant response to evaluate the effects of the oil and products on plant vigor and growth. This paper presents selected plant responses that demonstrated that the bioremediation products tested had no adverse impact on plant growth. Additionally, soil respiration was increased by fertilizer, but not microbial, application.

REMOVING OIL AND SAVING OILED MARSH GRASS USING A SHORELINE CLEANER

ABSTRACT A new shoreline cleaner, which was specially developed during the cleanup of the Valdez spill in Alaska, was tested to determine its effectiveness in removing oil from Louisiana Gulf Coast marsh grass thus minimizing the oil impact. Intact plugs of Spartina alterniflora containing living plants, roots, and soil microbial communities were collected from salt marshes and transferred to a greenhouse. Plant photosynthesis, respiration, and stomatal conductance were monitored following various oiling and cleaning scenarios. The treatments included: oiled, oiled and cleaned after one day, oiled and cleaned after two days, cleaner only, and control. Plant recovery depended upon the degree of oiling and the type of oil used. Fouling with bunker C oil caused almost total plant mortality unless the plants were cleaned with the shoreline cleaner. South Louisiana crude oil was less toxic but cleaning accelerated recovery as was evident by photosynthetic activity and other plant functions such as regeneration of new shoots. Collectively, these studies demonstrate the potential for saving an oiled Spartina alterniflora marsh by use of this shoreline cleaner in a real oil spill.

Foraging Behaviors of Snowy Egrets (Egretta thula) and Yellow-Crowned Night-Herons (Nyctanassa violacea) in South Louisiana

-We report two previously undescribed foraging techniques used by Snowy Egrets (Epettn thuln) and Yellow-crorvned Night-Herons (AVjctanarsa violacea) to catch crawfish (Procambaru.: spp.). Snowy Egrets were selecting crawfish that had recently molted their shells and Yellow-crowned Sight-Herons were targeting crawfish that were emerging from their burrows. These obsen.ations rvere conducted on com~nercial crarvfish ponds near Catahoula, L A , USA. Ri.ceiiled 2 June 1995, accepted 14 A u ~ c . : ~ 19%.

Improved Efficiency and Cost Savings: Horizontal Drilling, South Florence Field, Vermilion Parish, Louisiana: ABSTRACT

ABSTRACT Significant cost savings and improved recovery efficiency was demonstrated by the successful completion of a horizontal well in the south Louisiana middle Miocene trend of Vermilion Parish. This completion also represents the first gravel-packed horizontal well completion in the Gulf Coast. The Amoco No. 104 Watkins well was drilled in South Florence Field to a total depth of 6,878 MD (5,686 TVD) as a horizontal well to minimize coning. The well was completed in November, 1994 from an open hole completion over a 183 m (600) horizontal section (6,278-6,878 MD). The well tested as high as 1,079 BOPD, 769 MCFG, and 27 BW. The completed well cost of $1.2 MM represents $600 M savings over the cost of two vertical wells that would have been necessary to effectively drain the reservoir. The horizontal target interval was the upper 2.4 m (8) of a 45 m (148) sand with a 9.1 m (30) hydrocarbon column. A well was drilled before the No. 104 to serve as both a pilot hole and to test deeper objectives. The No. 104 was then drilled and encountered the top of the objective reservoir within 46 m (150) of the pilot hole. The trap is an upthrown fault closure on a down-to-the-east fault associated with the South Florence graben system, the result of deepseated salt movement. Structural control is provided by numerous wells and a 3-D seismic data set. An oil-water contact defines the downdip limit of this 0.26 km2 (63 acre) reservoir. The completed reservoir, the 5,400 Sand-lower lobe is a very fine-grained, silty deltaic sand with sidewall core porosities of 28.9-32.3% and permeabilities of 1,100-1,050 md.

A Computer Model for DNAPL Potential Migration Study

AbstractA computer model, named DNAPMIG (DNAPL Potential Migration), was developed to calculate the dense nonaqueous phase liquid (DNAPL) critical length required to initiate movement and direction of potential migration at locations within an area of interest. The model takes into consideration the potentiometric gradient, bottom structure elevation, DNAPL density, interfacial tension, contact angle, soil grain size, partitioning coefficient, effective solubility, and water saturation. The model is interfaced with SURFER graphics software to use vectors to indicate the DNAPL critical length and the potential migration direction. The potential for DNAPL existence and migration at a specific site can be estimated by relating chemical concentration in the ground water to its solubility limit and the DNAPL critical length. The possibility of vertical migration can also be determined.This model can be used to determine and compare the effectiveness of existing or alternative recovery well systems to capture a DNAPL plume or arrest its movement; to help determine optimum locations and pumping rates of recovery wells; and to help determine the optimum location of environmental borings to locate DNAPL. This paper presents two hypothetical examples and two site applications in south Louisiana.

Cajun and Creole folktales: the French oral tradition of South Louisiana

Cajun and Creole folktales: the French oral tradition of South Louisiana

Origin of Corn Earworm (Lepidoptera: Noctuidae) Migrants as Determined by Citrus Pollen Markers and Synoptic Weather Systems

Pollen on corn earworm moths, Helicoverpa zea (Boddie), can provide an indication of their host plant visitations and migratory activities. Our study was conducted to determine the origin of Citrus sp. pollen-contaminated moths captured in Atoka County, Oklahoma, during 1990 and the host plant feeding range of moths present in Hidalgo County, Texas, and Atoka County. Captured moths were analyzed for pollen with scanning electron microscopy. H. zea moths captured in January 1989 in the Lower Rio Grande Valley of Texas when citrus was not blooming were not contaminated with Citrus spp. pollen. Sixty percent of those captured on 17 March 1989 during the citrus blooming period were contaminated with Citrus sp. pollen. None of the moths sampled in that area between 21 March and 2 April 1990 were contaminated with Citrus spp. after a major freeze in December 1989. Citrus blooming during 1990 was drastically reduced or eliminated in South Texas, northeastern Mexico, Louisiana, and central Florida. However, Citrus sp. pollen accounted for 3% of all pollen detected on migratory H. zea collected in Atoka County between 27 February and 24 April 1990. Lack of Citrus spp. pollen-contaminated H. zea in Hidalgo County after the severe freeze suggests the H. zea contaminated with Citrus pollen was collected in Atoka County during April 1990 originated elsewhere. Evaluation of calculated trajectories, synoptic weather maps, and upper-air transport opportunities suggests southern Florida, the Bahamas, Cuba, Yucatan Peninsula, and northern Central America as potential source areas 1,515 km from the capture site. This would require the moths to be in flight over water for 72 h or have very limited diurnal resting periods on seaweed ( Sargassum spp.), ships, oil platforms, or the sea surface.

Longitudinal Trends in Violence in the Rural South

Since 1960, the number of violent crimes in America has increased by more than four hundred and fifty percent. Although the bulk of these crimes are being committed in urban areas, the rural areas of the country are not immune from the violence. Previous studies have noted that as a region, the South has one of the highest rates of arrests and incarcerations. Most studies on criminal violence have treated the region as a culturally monolithic entity without any recognition of differences in the patterns and distribution of violence in the rural areas of that region. The purpose of this paper is to examine variations in rural violence among twelve states in the southeastern United States using Uniform Crime Report data from 1962 to 1991. The study found that aggravated assault is the most common form of violent offending. This is followed by robbery, forcible rape, and homicide. For total violence, the rural areas of South Carolina, Florida, and Louisiana reported the highest rates. Total violence rates are lower in the rural areas of West Virginia, Arkansas, and Virginia.

An Integrated Geochemical and Geological Approach for Determining Hydrocarbon Generation-Migration Patterns: Central Gulf Coast Basin: ABSTRACT

ABSTRACT New geochemical, geological, and well-production data indicate a Mesozoic hydrocarbon source for many younger reservoirs in central Louisiana and southwest Mississippi. A Jurassic source has been determined for several Cretaceous reservoirs in oil and gas fields of northeast Louisiana. The characteristic Wilcox, Sparta, and Frio biomarker, Bisnorhopane, identified in Austin Chalk oils from southwest Mississippi, links these Mesozoic and Tertiary oils. Cross-plots of 13CAROM versus 13CSAT indicate an Upper Jurassic (Smackover) and Lower Cretaceous source for certain Upper Cretaceous and Tertiary oils. However, the pristane/nC17 ratio versus 13CSAT cross-plot indicates Wilcox and Sparta oils are heavily biodegraded Mesozoic (Lower Cretaceous) oils. There is an absence of gas accumulations in central Louisiana and southwest Mississippi in Midway, Wilcox, and Sparta reservoirs updip from coeval gas-prone source rocks. This is an indication of (1) a sealing regional fault system and/or stratigraphic migration barrier paralleling the Paleocene-Eocene shelf edge or (2) an earlier selective escape via vertical migration pathways. Vertical migration of hydrocarbons in northeast Louisiana, central Louisiana, and southwest Mississippi was accomplished primarily through fracture systems caused by wrench faulting; to the south and west, salt tectonics and related normal faulting played significant roles in the process. In onshore and offshore south Louisiana, normal faulting and salt-related tectonics created primary migration pathways. Regional hydrocarbon generation-migration patterns differ conceptually from those illustrated in previous models employing long-range migration based primarily on geochemical considerations. This new interpretation integrates geochemical, geological, and production data useful in identifying new exploration plays in north and central Louisiana and in southwest Mississippi.

In vitro red blood cell assay for oxidant toxicity of petroleum oil

AbstractPetroleum oil has caused hemolytic anemia in birds and mammals. In birds, an oxidant damage on circulating red cells has been identified as the primary toxic effect of ingested petroleum oils. An in vitro red blood cell assay was developed to discriminate among the oxidant activities of different petroleum oils. The assay used rabbit red blood cells with a rat liver enzyme system and formation of methemoglobin was measured as an indicator of oxidant damage to the red cells. The assay was applied to five different petroleum oils and to naphthalene, a petroleum hydrocarbon known to cause hemolytic anemia. Different petroleum oils differed in their capacity to induce methemoglobin formation. Methemoglobin levels varied from 2.9% with Arabian light crude oil to 6.2% with South Louisiana crude oil. Naphthalene induced formation of up to 37% methemoglobin. Naphthalene and the five petroleum oils generated methemoglobin only in the presence of liver enzymes.

Premorbid personality in patients with first onset psychoses

The Mississippi River Delta of south Louisiana USA is a highly engineered system with extensive levees, flood control, and diversion structures. This region is experiencing a high rate of coastal wetland loss. Solutions to divert or re-direct a portion of the River’s sediment to benefit wetlands and reduce coastal land-loss are considered. The question that must be answered, regarding the impact and feasibility of sediment diversions is: What is the sediment–water ratio at a diversion? To help answer this question a numerical model of hydrodynamics and sediment transport supported by extensive field data is used to analyze a proposed sediment diversion near Myrtle Grove, Louisiana. This location is at a River Kilometer 90 above the Head of Passes – exit of the Mississippi River to the Gulf of Mexico. The numerical model showed that the location of the diversion, the size and the alignment of the diversion channel are critical parameters affecting the sediment–water ratio captured by the diversion. The analysis shows that locating the intake near a lateral sandbar increases the sediment–water ratio in the diversion. Further, the analysis shows that a larger diversion channel with a favorable alignment orientation to the flow direction in the river results in higher sediment–water ratio.