April L. Ulery

Corrosion of Depleted Uranium in an Arid Environment: Soil-Geomorphology, SEM/EDS, XRD, and Electron Microprobe Analyses

Corrosion of anthropogenic uranium in natural environments is not well understood, but is important for determining potential health risks and mobility in the environment. A site in the southwestern United States contains depleted uranium that has been weathering for approximately 22 years. Soil-geomorphic, SEM/EDS, XRD, and electron microprobe analyses were conducted to determine the processes controlling the uranium corrosion. Schoepite and metaschoepite are the primary products of corrosion, and occur as silica-cemented, mixed schoepite-metaschoepite/clay/silt aggregates, as schoepite/metaschoepite-only aggregates, or rarely as coatings upon soil grains. Current extraction procedures do not adequately explain the behavior of uranium in alkaline soils when amorphous silica and clay coatings are present. Soil geomorphology and chemistry at this site limit uranium mobility and decreases potential health risks. However, if land-use and/or regional climate changes occur, uranium mobility could increase.

Animal Waste-Enhanced Degradation of Hydrocarbon-Contaminated Soil

Land previously used for petroleum production is being converted to commercial, industrial, or residential uses and requires remediation to remove petroleum hydrocarbons (HC). Concurrently, large quantities of animal wastes are produced annually, creating waste-handling and disposal problems. A laboratory study was conducted to determine whether amending contaminated soil with animal manure and inorganic fertilizer affected the degradation rate and amount of HC in the soil. HC-impacted soil was prepared by mixing a diesel fuel: motor oil solution (1:1 v/v) with a noncontaminated loamy sand, with a target concentration of 5000 mg HC per kg soil. Treatments included ammonium sul-fate fertilizer, composted steer manure at 5, 10, and 20% on a dry weight basis, and a mixture of fertilizer and steer manure, with three replications for each treatment. Five-gram aliquot soil samples were extracted with hexane. The extracts were analyzed using a gas chromatograph with a flame ionization detector. Over a period of 41 days, control treatment HC concentrations were reduced by 32%. Hydrocarbon concentrations in (NH4)2SO4 fertilizer-amended soil were decreased by nearly 54% during the same time. In contrast, HC degradation was much faster and more complete in manure-amended soils. Up to 81% of the HC in the 20% manure-treated soil were removed by day 41.

Transient Phytoextraction Agents: Establishing Criteria for the Use of Chelants in Phytoextraction of Recalcitrant Metals

The phytoremediation of recalcitrant metals such as lead and uranium rely on soil amendments to enhance metal availability within the rhizosphere. Because these amendments may persist in soils, agents that not only biodegrade rapidly but also are effective in triggering metal uptake in plants are needed for metals phytoextraction to be considered as an accepted practice. In this study, several biodegradable organic acids and chelating agents were assessed to determine if these amendments can be used in an effective manner, and if their activity and use is consistent with a proposed class of soil amendments for phytoextraction, here termed transient phytoextraction agents (TPAs). A TPA is proposed as an agent that would exhibit both effectiveness in triggering plant accumulation of the targeted metal while minimizing the risk of migration through rapid degradation or inactivation of the soluble complex. Eleven candidate TPAs (acetic acid, ascorbic acid, citric acid, malic acid, oxalic acid, succinic acid, ethylenediaminedisuccinic acid, dicarboxymethylglutamic acid, nitrilotriacetic acid, BayPure® CX 100, and the siderophore desferrioxamine B) were tested in batch studies to evaluate their complexation behavior using contaminated soils, with uranium and lead as the target metals. A growth chamber study was then conducted with Brassica juncea (Indian mustard), Helianthus annuus (sunflower), and Festuca arundinacea (tall fescue) grown in a lead-contaminated soil that was treated with the candidate TPAs to assess phytoextraction effectiveness. For the soils tested, citric acid, oxalic acid, and succinic acid were found to be effective complexing agents for uranium phytoextraction, whereas Baypure® CX 100 and citric acid exhibited effectiveness for lead phytoextraction.

New Mexico Blue Grama Rangeland Response to Dairy Manure Application

Abstract New Mexico supports over 290 000 dairy cattle. These cattle produce large quantities of manure. It has been suggested excess dairy manure could be applied to rangelands as an organic fertilizer to increase soil fertility and herbaceous production. Manure was applied June 2000 to a rangeland in New Mexico dominated by blue grama (Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths) according to phosphorus (P) content: a recommended (light) rate (54 kg P·ha−1) to enhance blue grama growth and a gross overapplication (heavy) rate (493 kg P·ha−1) to determine their effects on vegetation. The actual application rate of manure on a dry weight basis was 0, 11 739, and 107 174 kg·ha−1. Four replications of control, light, and heavy rates were established. Herbaceous standing crop (kg·ha−1) was similar 1 growing season after manure application, and greater 2 and 3 growing seasons after application on the light treatment compared with the control. Initially the heavy treatment suppressed herbaceous standing crop; thereafter, standing crop responded in a linear fashion to rainfall. Three growing seasons after manure application, basal cover was similar between light and control treatments, whereas the heavy treatment continued to be characterized principally by manure/litter cover. Heavy disposal-oriented treatments are not suitable for blue grama rangelands because of persistent declines in herbaceous cover and changes in soil salinity. A light manure application rate that is based on P content can increase forb and in particular grass standing crop on arid blue grama rangelands. Successful rangeland manure applications will depend on proper management to insure objectives are met while minimizing any hazards to the environment.

Genetic variation in metallothionein and metal-regulatory transcription factor 1 in relation to urinary cadmium, copper, and zinc.

BACKGROUND Metallothionein (MT) proteins play critical roles in the physiological handling of both essential (Cu and Zn) and toxic (Cd) metals. MT expression is regulated by metal-regulatory transcription factor 1 (MTF1). Hence, genetic variation in the MT gene family and MTF1 might influence excretion of these metals. METHODS 321 women were recruited in Seattle, WA and Las Cruces, NM and provided demographic information, urine samples for measurement of metal concentrations by mass spectrometry and creatinine, and blood or saliva for extraction of DNA. Forty-one single nucleotide polymorphisms (SNPs) within the MTF1 gene region and the region of chromosome 16 encoding the MT gene family were selected for genotyping in addition to an ancestry informative marker panel. Linear regression was used to estimate the association of SNPs with urinary Cd, Cu, and Zn, adjusted for age, urinary creatinine, smoking history, study site, and ancestry. RESULTS Minor alleles of rs28366003 and rs10636 near the MT2A gene were associated with lower urinary Cd, Cu, and Zn. Minor alleles of rs8044719 and rs1599823, near MT1A and MT1B, were associated with lower urinary Cd and Zn, respectively. Minor alleles of rs4653329 in MTF1 were associated with lower urinary Cd. CONCLUSIONS These results suggest that genetic variation in the MT gene region and MTF1 influences urinary Cd, Cu, and Zn excretion.

Fly Ash and Composted Biosolids as a Source of Fe for Hybrid Poplar: A Greenhouse Study

Soils of northwest New Mexico have an elevated pH and CaCO3 content that reduces Fe solubility, causes chlorosis, and reduces crop yields. Could biosolids and fly ash, enriched with Fe, provide safe alternatives to expensive Fe EDDHA (sodium ferric ethylenediamine di-(o-hydroxyphenyl-acetate)) fertilizers applied to Populus hybrid plots? Hybrid OP-367 was cultivated on a Doak sandy loam soil amended with composted biosolids or fly ash at three agricultural rates. Fly ash and Fe EDDHA treatments received urea ammonium nitrate (UAN), biosolids, enriched with N, did not. Both amendments improved soil and plant Fe. Heavy metals were below EPA regulations, but high B levels were noted in leaves of trees treated at the highest fly ash rate. pH increased in fly ash soil while salinity increased in biosolids-treated soil. Chlorosis rankings improved in poplars amended with both byproducts, although composted biosolids offered the most potential at improving Fe/tree growth cheaply without the need for synthetic inputs.

Plant Uptake of Depleted Uranium from Manure-Amended and Citrate Treated Soil

Six plant species were tested for their ability to accumulate depleted uranium in their aboveground biomass from deployed munitions contaminated soil in New Mexico. In greenhouse experiments, Kochia (Kochia scoparia L. Schrad.) and pigweed (Amaranthus retroflexus L.) were grown with steer manure added at rates of 22.4, 44.8, and 89.6 Mg ha−1. Citric acid and glyphosate (N-(phosphonomethyl) glycine) applied at the end of the growing season increased DU concentrations from 2.5 to 17 times. Leaf and stem DU concentrations in kochia increased from 17.0 to 41.9 mg kg−1 and from 3.5 to 18.0 mg kg−1, respectively. In pigweed, leaf and stem DU concentrations increased from 1.0 to 17.3 and from 1.0 to 4.7 mg kg−1, respectively. Manure generally decreased or had no effect on DU uptake. The effect of citric acid and ammonium citrate on DU uptake by kochia, sunflower (Helianthus annuus L.), and sweet corn (Zea mays L.) was also studied. Ammonium citrate was just as effective in enhancing DU uptake as citric acid. This implies that the citrate ion is more important in DU uptake and translocation than the solubilization of DU through acidification. In both experiments, leaves had higher DU concentrations than stems.

Moderate Salinity Does Not Affect Germination of Several Cool‐ and Warm‐Season Turfgrasses

Germination of warm- and cool-season turfgrasses was assessed at salinity levels commonly found in recycled irrigation water. Cool-season grass seeds included in the study were Thermal Blue hybrid bluegrass [Poa arachnifera (Torr.) x pratensis (L.)]; Barlexas II, Southeast, and Tar Heel II tall fescue [Festuca arundinacea (Schreb.)]; Brightstar SLT and Catalina perennial ryegrass [Lolium perenne (L.)]; Salty and Fults alkaligrass [Puccinellia distans (Jacq.)]; and Dawson red fescue [Festuca rubra trichophylla (L.)]. Warm-season grass seeds used in the study were bermudagrass Numex Sahara, Princess 77, and Transcontinental [Cynodon dactylon (L.)]; Companion zoysiagrass [Zoysia japonica (Steud)]; and Seaspray seashore paspalum [Paspalum vaginatum (Swartz)]. Each grass was incubated at salinity levels from 0.6 to3.0 dS/m. Germination was considered successful upon radicle emergence and the first leaf growing past the coleoptile. Despite species and cultivar variation in germination success, germination was not inhibited in any of the tested cultivars at the salinity levels used in this study, suggesting that germination may not be the most salt-sensitive stage in turfgrass development.

Distribution of Petroleum and Aromatic Hydrocarbons at a Former Crude Oil and Natural Gas Production Facility

Site characterization and remediation activities were performed at a former crude oil and natural gas production facility prior to redevelopment of the site. Field activities included delineation, excavation and segregation of approximately 1,250,000 m3 of soil impacted by total petroleum hydrocarbons (TPH) and the aromatic volatile organic compounds (VOCs) benzene, toluene, ethylbenzene, and xylenes (hereafter, collectively referred to as BTEX). Petroleum hydrocarbon chain length information was used to determine whether remediation was required in impacted areas, because the site-specific cleanup values for TPH compounds, established by the California State Regional Water Quality Control Board (RWQCB), were based on hydrocarbon chain length. Site-specific cleanup levels were also established by the RWQCB for BTEX. Subsurface investigation activities performed at the site indicated that the mean percentage of condensate and TPH compounds in the gasoline range was significantly greater at depths ranging from 4.6 to 18 m than in shallower samples. There was no significant difference in the mean concentration of BTEX compounds and mean percentage of diesel range and heavier hydrocarbons with depth. The occurrence of BTEX, diesel range, and heavier hydrocarbons at depth may result from preferential pathways for downward migration of contaminants, including blown out wells, abandoned wellbores, and the presence of faults. Vapor phase diffusion may also be a major transport mechanism controlling movement of BTEX compounds beneath the site.

Elevated Soil Arsenic Levels at a Former Crude Oil Storage Facility-Assessment, Remediation, and Possible Sources

Surface and near-surface soil arsenic levels were measured at a former crude oil storage facility within the greater Los Angeles area of Southern California. Arsenic was present in soil within some portions of the site at concentrations defined as being hazardous by both the State of California and the United States Environmental Protection Agency. The elevated soil total arsenic concentrations ranged from about 30 to 2300 mg/kg and generally occurred in, and adjacent to, the former washing and storage tank locations and along piping runs. In contrast, background concentrations of arsenic in soil at the site ranged from less than the analytical method detection limits (0.5 mg/kg) to approximately 8.0 mg/kg. The elevated soil arsenic concentrations are believed to be the result of the use of arsenical corrosion inhibitors within production wells and possibly the use of arsenical biocides in washing and skimmer tanks. Flow lines from production wells within the oil field to the crude oil storage facility co...