Publications

3H, He, 4He, and Ne data were obtained from a shallow ground-water system being recharged by bank infiltration from the Danube River in northwestern Hungary. After correting for excess air, 4He and Ne concentrations reflect a recharge temperature of about 9° C., close to the mean annual temperature of the Danube (10.4° C). Values of H plus 3Hetrit (“initial tritium”) as a function of the...

Microorganisms indigenous to a shallow aquifer, which underlies an explosives-contaminated site, mineralized 28% of [U-ring-14C] 2,4–dinitrotoluene to 14CO2 within 28 days under aerobic conditions. Approximately 20% of added 2,4–dinitrotoluene remained undegraded at the end of the incubation while approximately 22% and 6% were transformed to 4–amino-2–nitrotoluene and 2–amino-4...

No abstract available.

No abstract available.

No abstract available.

A spring runoff pulse is identified in the Merced River record from the Sierra Nevada, that makes the transition from low streamflow conditions in winter to the high streamflow conditions in the later spring-early summer period. The timing of the pulse is delayed with greater seasonal accumulation of snow pack in the Yosemite region. Also, the runoff pulse is triggered by a regional...

In a column experiment, acidic groundwater from Pinal Creek Arizona, a Cu mining area, was eluted through a composited alluvial sample obtained from a core that had been removed from a well downgradient of the acidic groundwater. The minerals present in typical grains and flakes in the alluvium before and after the elution were determined by X-ray diffraction (XRD), scanning electron...

The chemical relationships among particulate and colloidal organic material and dissolved fulvic acid were examined in an alpine and subalpine lake and two streams in Loch Vale Watershed, Rocky Mountain National Park. The alpine lake, Sky Pond, had the lowest dissolved organic carbon (DOC) (0.37 mgC/L), the highest particulate carbon (POC) (0.13 mgC/L), and high algal biomass. The...

Buoyant densities were determined for groundwater bacteria and microflagellates (protozoa) from a sandy aquifer (Cape Cod, MA) using two methods:  (1) density-gradient centrifugation (DGC) and (2) Stoke's law approximations using sedimentation rates observed during natural-gradient injection and recovery tests. The dwarf (average cell size, 0.3 μm), unattached bacteria inhabiting a...

Rain and surface water samples from Southern Germany were investigated from 1991 to 1995 for terbuthylazine and one of its major metabolites, deethylterbuthylazine. The concentrations observed were compared to the concentrations found for atrazine and deethylatrazine in the same water samples. Concentrations ranged from 0.02 μg/L to 0.7 μg/L for terbuthylazine and from 0.02 μg/L to 0.6...

Single-well injection/recovery tracer tests are considered for use in characterizing and quantifying matrix diffusion in dual-porosity aquifers. Numerical modeling indicates that neither regional drift in homogeneous aquifers, nor heterogeneity in aquifers having no regional drift, nor hydrodynamic dispersion significantly affects these tests. However, when drift is coupled...

Natural surficial accumulations of nitrate-rich salts in the Atacama Desert, northern Chile, and in the Death Valley region of the Mojave Desert, southern California, are well known, but despite many geologic and geochemical studies, the origins of the nitrates have remained controversial. N and O isotopes in nitrate, and S isotopes in coexisting soluble sulfate, were measured to...