Jeffrey L. Means

Short-chain aliphatic acid anions in deep subsurface brines: A review of their origin, occurrence, properties, and importance and new data on their distribution and geochemical implications in the Palo Duro Basin, Texas

Abstract Short-chain aliphatic acid anions, which are produced during the thermal maturation of sedimentary organic matter, are common in oil-field brines and other deep formation fluids. Their abundance and distribution are controlled primarily by their rates of formation, thermal and bacterial destruction, and reservoir flushing. This first part of this manuscript reviews literature on their abundance and distribution in deep basin brines, their geochemical and biogeochemical properties, and their geochemical importance, which far outweighs the number of analytical measurements that have been published. The second part reports new data from the Palo Duro Basin in the Texas Panhandle. Deep brines from the Palo Basin contain short-chain aliphatic acid anions in concentrations ranging up to 440 mg/l. The observed order of abundance is acetate ≫ propionate > butyrate > valerate. Aliphatic acid anion contents vary randomly with subsurface temperature, depth, and geologic age, but correlate well with groundwater residence time, as inferred from δ18O measurements. Groundwaters having the longest residence times contain the highest organic acid anion contents. Organic content, I−, and Br− in these deep brines appear to have a common source, and all of the aliphatic acid anions, most of the I− and some portion of the Br− are interpreted to have been derived from lipid-rich sedimentary organic matter. This observation complicates the use of Br− as a conservative marker constituent when inferring groundwater origin and evolution using Cl−/Br− relationships. Also, simplified calculations indicate that these organic acid anions are not important in complexing metals. Their presence in relatively high concentrations in this basin with its low petroleum potential indicates that they cannot be used alone as petroleum proximity indicators.

The environmental biogeochemistry of chelating agents and recommendations for the disposal of chelated radioactive wastes

Abstract Chelating agents are used in nuclear decontamination operations because they form very selective and strong complexes with numerous radionuclides. However, if environmentally-persistent chelated wastes are disposed of without pretreatment to eliminate the chelating agents, increased radionuclide migration rates from the disposal sites may occur. The environmental chemistry of the three most common aminopolycarboxylic acid chelating agents, NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid), and DTPA (diethylenetriaminepentaacetic acid) is reviewed. This review includes information on their persistence in the environment, as well as their tendency to form complexes with actinides. Data on the sorption of chelated actinides by geologic substrates and on the uptake of chelated actinides by plants are also presented. Increased solubility and/or migration of radionuclides by chelating agents used in decontamination operations have been observed at two different radioactive waste burial grounds. EDTA was found to be promoting the migration of 6O Co and possibly other radionuclides from liquid waste disposal sites at Oak Ridge National Laboratory (1). Recently EDTA has again been identified in radioactive wastes-this time in trench waters containing from 600–16,100 pCi 238 Pu per liter from solid waste burial grounds in Maxey Flats, Kentucky (2). These observations at Oak Ridge and Maxey Flats suggest that the practice of disposing chelated radioactive wastes should be reevaluated. Three different technical options for disposing chelated low-level radioactive wastes are proposed: 1. [1] Bind the solidified chelated waste in some kind of solid matrix that has a slow leach rate and bury the waste in a “dry” disposal site. 2. [2] Substitute biodegradable chelating agents in the decontamination reagent for the chelating agents that are persistent in the environment. 3. [3] Chemically or thermally degrade the chelating agents in the waste prior to disposal. The relative advantages and disadvantages of each of these options are discussed. We feel that surprisingly little attention has been given to an obvious procedure for the disposal of chelated radioactive wastes: chemically or thermally degrading the chelating agent prior to disposal. Any of the above three options might in fact be a satisfactory approach to the disposal of chelated wastes. However, we suggest that the burial of chelating agents such as EDTA be avoided and that option [3] be given more consideration.

Comparison of five different methods for measuring biodegradability in aqueous environments

The biodegradabilities of five different organic compounds of environmental concern: aniline, benzaldehyde, ethylene glycol, nitrilotriacetic acid (NTA), andp-nitrophenol, were measured using five different procedures: the BOD, Shake Flask, CO2 Evolution, and Activated Sludge tests and a test developed by Gledhill (1975). Aniline, benzaldehyde, and ethylene glycol were metabolized rapidly in all the tests. However NTA andp-nitrophenol degraded relatively rapidly in some and slowly or not at all in others. The reason for these inconsistencies are evaluated relative to the physical, chemical, and biological conditions inherent in each test. The applicability of results from such tests to predicting the biodegradability of a chemical in the environment is also discussed.

Sorption of uranium by brine-saturated halite, mudstone and carbonate minerals

Abstract Batch and column sorption experiments were conducted to quantify the retardation of uranium in brine-saturated halite, LSA-4 carbonate, Wolfcamp carbonate, and mudstone from Palo Duro Basin, Texas, one of the three sites originally nominated by U.S. Department of Energy for construction of a civilian nuclear waste repository. The data indicated a very strong retardation of uranium by all media. Retardation factors computed from batch experiments were 4.32, 17.2, and 10.3 for halite, LSA-4 carbonate, and Wolfcamp carbonate, respectively. Due to nonlinearity of the log-transformed batch data, no retardation factor was computed for mudstone. Predictions with an advection-dispersion-sorption model did not agree with the halite experimental data, but were in partial agreement with the LSA-4 carbonate experimental breakthrough curves.

Use of hydrogen peroxide as an oxygen source for in situ biodegradation: Part II. Laboratory studies

Abstract A review of the literature on hydrogen peroxide decomposition and stabilization identified several inorganic and organic compounds that are known to decrease the rate of decomposition of peroxide in simple systems. Phosphate, a commonly used stabilizer in groundwater applications, does not stabilize peroxide in the presence of enzymatic catalysts, primarily catalase, which are the most important catalysts of peroxide decomposition. In laboratory experiments, a variety of other peroxide stabilizers identified in the literature review also did not sufficiently stabilize peroxide. It is concluded that hydrogen peroxide may not be an efficient source of oxygen for in situ bioreclamation processes, at the Eglin Air Force Base, Florida site.

The Feasibility of Recycling Spent Hazardous Sandblasting Grit into Asphalt Concrete

Summary The recycling of spent sandblasting grit, commonly referred to as spent abrasive blast material (ABM), into asphalt concrete is being investigated by the U.S. Navy as an alternative to disposing the spent ABM in a landfill. This paper discusses issues related to the technical feasibility and regulatory acceptability of this concept. These issues include the chemical characterization of spent ABM, asphalt mix design criteria, the results of bench-scale tests, regulatory compliance issues, and a discussion of the advantages and disadvantages of recycling spent ABM into asphalt concrete. The merits of recycling versus some other option should be evaluated on a case-by-case basis.

Remediation of Lead-Contaminated Soils at Small Arms Ranges

The objectives of this study were to assess the level of lead contamination at the US Navy`s small arms ranges, to determine the potential for non-point source pollution, and to select and apply a remediation technology suitable to such sites. A combination of screening and stabilization were selected as the best remedy following bench-scale and field-pilot testing. Binders tested at bench scale included cement, cement-silicate, and lime-fly ash. Optimum treatment was achieved with either cement or a combination of cement and silicate.