Journell, Scot (Arizona-Nevada Academy of Science, 1990-04-21)
Remedial techniques for sub-surface soil and water contamination are dependent on the lateral and vertical extent of petroleum hydrocarbon contamination and the type of petroleum hydrocarbons which have been released into the sub-surface. Specific remedial technologies are required for diesel fuel and heavy oils compared to the more volatile gasoline compounds. Available remedial technologies for vadose zone contamination include excavation and treatment; soil vapor extraction and possible vapor burning; bioremediation; and chemical treatment. Remedial technologies for ground-water contamination include water recovery, contaminant volatilization, carbon adsorption, bioremediation and water reinjection. Specialized apparatuses are utilized when petroleum hydrocarbon product floating on the water table surface must be separated from the ground water. A number of hydrologic considerations must be evaluated prior to any remediation scenario. These considerations include geologic characterization of the sub-surface soil matrix, and aquifer.
Darwiche, Amal O.; Ffolliott, Peter F. (Arizona-Nevada Academy of Science, 1990-04-21)
Effects of applications of cytokinin-like and gibberellic growth regulators, nitrogen fertilizer, and irrigation on the development of containerized eldarica pine (Pinus brutia var. eldarica) seedlings was studied in a greenhouse for 13 weeks. All concentrations of growth regulators reduced nitrogen content of needles and dry weight of shoots; importantly, medium and high concentrations also adversely affected root collar diameter growth and shoot elongation. Nitrogen fertilization alone was not significant in its effect on seedling development, due probably to the nitrogen-rich nature of the potting medium. It is suggested that contentration is a critical factor when applying growth regulators, as phytotoxicity of seedlings can result at high rates.
Hebert, Kevin D. (Arizona-Nevada Academy of Science, 1990-04-21)
New regulations concerning the management of underground storage tanks (USTs) have resulted in increased awareness of environmental contamination resulting from leaking USTs. The objective of the typical underground storage tank investigation is to determine if any subsurface contamination has occurred as a result of tank or product line leakage, fuel spills or overfills. Soil contamination at underground storage tank sites is usually discovered during the removal and replacement of USTs. Techniques that can be used to detect the presence of soil contamination adjacent to existing USTs include soil vapor analysis, exploratory boring, and soil and ground water sampling. The lateral and vertical extent of contamination must be determined at any site which contains detectable quantities of contamination. Two common methods for determining the extent of contamination are over-excavation and borehole drilling and sampling. Boring design and location considerations include number of borings, borehole depth and spacing, and site sub -surface conditions. Differentiation between perched sub -surface water and aquifers is critical. Once an appropriate boring plan has been established, then a sampling and analysis plan must be adopted that meets the needs of the particular investigation. The determination of the extent of contamination at an underground storage tank site is the first step leading to site closure and remediation.
Young, Don W.; Colmer, Gerald; Goodwin, Scott (Arizona-Nevada Academy of Science, 1990-04-21)
During the summer of 1989, a water balance study was conducted at Lee Valley Reservoir, located approximately 19 miles southwest of the town of Eagar in Apache County, Arizona. The objectives of this study were to quantify evaporation and seepage losses from the lake and substantiate the use of a land-based evaporation pan to estimate lake evaporation. Lake level, inflow, controlled releases, precipitation and evaporation were measured on a twice weekly basis for six months from May 1 to October 31. Evaporation was measured in a Class A evaporation pan designed to float in the reservoir. Evaporation was also measured at a Class A land pan near the town of Eagar. A 1.0 inch difference in the estimated rate and the measured rate for a 147-day period of common record represents a 3.6% error between the land-based pan and the floating pan. Total losses from the lake over the six -month period were 224 acre-feet. Of this loss controlled releases accounted for 8.2 acre-feet, and evaporation was measured at 116 acre-feet. The remaining loss of 100 acre-feet is due to seepage, much of which can be seen as seeps rising within 800 feet downstream from the dam. Using average data from past years, an annual water balance for the lake was also calculated.
Amalfi, Frederick A.; Atkinson, Elizabeth M.; McNaughton, Julie D.; Sommerfeld, Milton R. (Arizona-Nevada Academy of Science, 1990-04-21)
A test protocol was evaluated for estimating the acute toxicity of urban stormwater runoff to aquatic life. Potential deleterious effects of storm flows on the aquatic community of small artificial impoundments were examined by application of short-term bioassays. Definitive, static renewal, acute toxicity tests were performed using the fathead minnow, Pimephales promelas, and the crustacean, Daphnia magna. The feasibility study indicated that short-term bioassays may provide an alternative to individual chemical constituent measurements and comparisons to numerical water quality criteria for protection of aquatic life. Biotoxicity tests may identify synergistic interactions to chemicals which individually meet specific water quality criteria but collectively lead to toxicity.
Hawkins, Richard H. (Arizona-Nevada Academy of Science, 1990-04-21)
A study of over 11,000 event rainfall and associated direct runoff events from 100 small watersheds was done, in a search for distinct patterns of runoff response and/or association with land type. The results show unexpected variety in the geometry and scale of the rainfall -runoff response. Groupings of similar response type and magnitude were made, and the associations with vegetative cover were tested. Five separate response groups were identified as follows: 1) Inactive, characterized by no recorded responses to any rainstorm in an extended period of record; 2) Complacent, characterized by a very small part of the rainfall (ca 0.1 to 3 percent) being converted to direct runoff, often as a linear response; 3) Standard behavior, the expected "textbook" response common to agricultural lands and humid sites, and in which the runoff slope increases with increasing rainfall, and the scale of runoff far exceeds the complacent response; 4) Violent behavior, in which an abstraction threshold of 2 -6 cm clearly precedes a sudden high response; and 5) Abrupt response in which a very high portion of the rainfall is converted to event runoff without appreciable abstraction, as typified by extensively urbanized drainages. The responses and the group identifications were parameterized by a simple broken -line linear rainfall-runoff equation, and a dichotomous key based on coefficient values is proposed. Only mild associations between response type or coefficient values and the four vegetative covers (Forest, Range, Agriculture, and Urban) were found. The variety of hydrologic behavior on forested watersheds encompassed that of the other three land types.
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