Geology topics

V. C. Kennedy

Publications and source records attributed to V. C. Kennedy.

17 recordsLinked to original sources

USGS2010

Variation of rain chemistry during storms at two sites in northern California

The chemical composition of rainfall at Menlo Park, on San Francisco Bay, is compared with rainfall at Petrolia, which is near the coast about 500 km north of San Francisco. Sequential samples representing 1.35 to 5.4 mm of rain were collected from November 1971 to January 1972. At rural Petrolia the Cl:Na ratio was that of seawater for Cl concentrations ranging from 0.02 to 38 mg/l. In metropolitan Menlo Park the Cl:Na ratio in rain closely approximated that in seawater above about 0.5 mg/l Cl, but at lower Cl concentrations the ratio exceeded that in seawater, a fact attributed to the presence of anthropogenic Cl. Other constituents dissolved in Menlo Park rain (along with their concentration ranges in milligrams per liter), and believed to be derived in part from anthropogenic sources, were Ca (0.01–1.07), Mg (<0.01–1.08), Pb (0.003–0.035), Zn (0.002–0.013), Mn (0.0001–0.0057), Cu (0.0008–0.0024), NO 3 ‐N (0.02–0.54), and Br (<0.01–0.12). The range of p H values was smaller in the rural than in the metropolitan areas; average H + activity corresponded to a p H of 5.1 to 5.2 in both areas. At Petrolia, p H decreased with increased dissolved salts in rainfall, but no relation between p H and dissolved salts was evident at Menlo Park.

California↗

USGS2002

Snow chemistry of the Cascade-Sierra Nevada Mountains

This investigation assesses geographic variations in atmospheric deposition in Washington, Oregon, and California using snow cores from the Cascade-Sierra Nevada Mountains, collected from late February to mid-March 1983. A statistical analysis of the analytical and sampling precision was made. The snowpack in the higher Cascades and Sierra Nevada is not strongly influenced by anthropogenic activities at present. The pH of snow samples ranges from 5.11 to 5.88. Sulfate and nitrate correlate with H+ in some segments of the sample traverse. The SO4 data show apparent influence from major source areas in Washington and California; nitrate does not. An apparent decrease in NH4 in snow in Washington and California suggests atmospheric interactions resulting in the removal of NH4. The NH4 reduction raises questions about nutrient supply to the mountain vegetation. Heavy-metal correlations included Cd, Cu, and Fe with Pb, and Mn with K and DOC, among others. No correlation was found between constituents and snow-water content.

California, Oregon, Washington↗

USGS2001

Interparticle migration of metal cations in stream sediments as a factor in toxics transport

Sorption of metal cations by stream sediments is an important process affecting the movement of released contaminants in the environment. The ability of cations to desorb from one sediment particle and subsequently sorb to another can greatly affect metal transport rates but rates for this process have not been reported. The objective of this study was to determine the rate at which sorbed metals can migrate from contaminated sediment particles to uncontaminated sediment particles as a function of the concentration of the contaminating solution and the duration of the contact with the contaminating solution. Samples of small sediment particles were exposed to solutions containing cobalt, after which they were rinsed and combined with larger uncontaminated sediment particles in the presence of stream water. Initial concentrations of the contaminating solution ranged from 1ng/l to 1000mg/l and exposures to the contaminating solution ranged from 6h to 14 days. The rate of the migration increased with increasing concentrations in the contaminating solution and with decreasing times of exposure to the contaminating solution. Under the conditions of these experiments, the time required for the migration to reach equilibrium was on the order of months or longer. In separate experiments, the kinetics of adsorption and desorption of cobalt were measured as a function of concentration of the contaminating solution. The time required to reach adsorption equilibrium increased with increasing concentration in the contaminating solution. Times to sorption equilibrium were on the order of months. Desorption was much slower than adsorption and, together with intraparticle diffusion, probably controls the rate of migration from contaminated to uncontaminated sediment. The results of this study show that interparticle migration of metal cations can proceed at significant rates that are strongly influenced by the length of time that the metal has been in contact with the sediment. Copyright ?? 2001 Elsevier Science B.V.Sorption of metal cations by stream sediments is an important process affecting the movement of released contaminants in the environment. The ability of cations to desorb from one sediment particle and subsequently sorb to another can greatly affect metal transport rates but rates for this process have not been reported. The objective of this study was to determine the rate at which sorbed metals can migrate from contaminated sediment particles to uncontaminated sediment particles as a function of the concentration of the contaminating solution and the duration of the contact with the contaminating solution. Samples of small sediment particles were exposed to solutions containing cobalt, after which they were rinsed and combined with larger uncontaminated sediment particles in the presence of stream water. Initial concentrations of the contaminating solution ranged from 1 ng/l to 1000 mg/l and exposures to the contaminating solution ranged from 6 h to 14 days. The rate of the migration increased with increasing concentrations in the contaminating solution and with decreasing times of exposure to the contaminating solution. Under the conditions of these experiments, the time required for the migration to reach equilibrium was on the order of months or longer. In separate experiments, the kinetics of adsorption and desorption of cobalt were measured as a function of concentration of the contaminating solution. The time required to reach adsorption equilibrium increased with increasing concentration in the contaminating solution. Times to sorption equilibrium were on the order of months. Desorption was much slower than adsorption and, together with intraparticle diffusion, probably controls the rate of migration from contaminated to uncontaminated sediment. The results of this study show that interparticle migration of metal cations can proceed at significant rates that are strongly influenced by the length of time that the metal has

Journal of Hazardous Materials↗

USGS1989

Retention and transport of nutrients in a third-order stream in northwestern California; hyporheic processes

Chloride and nitrate were coinjected into the surface waters of a third—order stream for 20 d to examine solute retention, and the fate of nitrate during subsurface transport. A series of wells (shallow pits) 0.5—10 m from the adjacent channel were sampled to estimate the lateral interflow of water. Two subsurface return flows beneath the wetted channel were also examined. The conservative tracer (chloride) was hydrologically transported to all wells. Stream water was >88% of flow in wells <4 m from the wetted channel. The lowest percentage of stream water was 47% at a well 10 m perpendicular to the stream. Retention of solutes was greater in the hyporheic zone than in the channel under summer low—flow conditions. Nominal travel time (the interval required for chloride concentration to reach 50% of the plateau concentration) was variable by well location, indicating different flow paths and presumably permeability differences in subsurface gravels. Nominal travel time was M 24 h for wells <5 m from the wetted channel. Coinjected nitrate was not conservative. Two wells were significantly (P < .05) higher in nitrate—N than would be predicted from chloride, while four were significantly lower. Wells 2.0—4.0 m from the wetted channel tended to have higher nitrate concentration than predicted, whereas nitrate sink locations tended to have transport distances >4.3 m. The capacity of the hyporheic zone for transient solute storage and as potential biological habitat varies with channel morphology, bed roughness, and permeability. A conceptual model that considers the groundwater—stream water interface as the fluvial boundary is proposed. Emerging paradigms of the riverine network should consider the hyporheic zone and associated nutrient cycling as an integral component of fluvial structure and function.

Ecology↗

USGS1986

Determination of the components of stormflow using water chemistry and environmental isotopes, Mattole River basin, California

The chemical and isotopic composition of rainfall and stream water was monitored during a storm in the Mattole River basin of northwestern California. About 250 mm of rain fell during 6 days (∼80% within a 42 h period) in late January, 1972, following 24 days of little or no precipitation. River discharge near Petrolia increased from 22 m 3 s −1 to a maximum of 1300 m 3 s −1 while chloride and silica concentrations decreased only from 3.2 to 2.1 and 11.5 to 8.6 mgl −1 , respectively. Meanwhile, the isotopic composition of the river changed from δD = -42%, δ 18 O = -6.8% and 40 tritium units (T.U.) to extreme values at highest flow of δD = -35%, δ 18 O = -5.9% and 25 T.U. in response to volume-weighted rainfall averaging δD = -19.5%, δ 18 O = -3.1% and 18 T.U. Despite much rainfall of a composition quite different from that of the prestorm river water, “buffering” processes in the watershed greatly restricted changes in the chemical and isotopic content of the river during storm runoff. Because of the physical and hydrologic characteristics of the watershed, major contributions of groundwater to stormflow are very unlikely. The large increase in dissolved chemical load observed at maximum river discharge required that extensive interaction with, and presumably penetration of, soils occurred within a few hours time. Such a large increase in chemical load also required subsurface stormflow throughout a high proportion of the watershed. Chemical and isotopic stabilization of stormflow is believed to be due mainly to displacement of prestorm soil water, with some effects on river chemistry due to rapid rain-soil interactions. The isotopic and chemical composition of prestorm soil moisture cannot readily be predicted a priori because of possible variability in rainfall composition, evaporation, and exchange with atmospheric moisture, nor can it be assumed that baseflow has a predictable relation to the chemical or isotopic composition of water displaced from soils during storms. Therefore, it seems inappropriate to draw conclusions as to the relative proportions of groundwater and rainfall in runoff from a particular storm based only on the average compositions of rainfall, stormflow, and prestorm river water, as has been done in most previous isotope hydrograph studies. Given the great variation in hydrology, topography, soil characteristics, rainfall intensity and quantity, etc. from place to place, the relative amount of overland flow, subsurface flow from the unsaturated zone and of groundwater in stormflow can vary greatly in time and space.

California↗

USGS1986

Data on the solute concentration within the subsurface flows of Little Lost Man Creek in response to a transport experiment, Redwood National Park, northwest California

A solute transport experiment was conducted on a 327-m reach of Little Lost Man Creek, a small stream in Humboldt County, California. Solutes were injected for 20 days. Chloride was used as a conservative tracer; lithium, potassium, and strontium were used as reactive tracers. In addition, nitrate and phosphate were added as biological reactants. Eighteen shallow wells were dug along the length of the study reach, 1-10 m laterally from the edge of the stream. The wells and sites in the stream were monitored for the injected solutes during and after the injection. Solute concentrations in the wells and stream are indicative of transport properties of stream and subsurface channel flow. This report presents the results of the analyses of the well samples and chemical data relevant to the interpretation of hydrological and chemical interaction between the stream and adjacent channel subsurface flows in the streambed. Calculations of the percentage of streamwater in the wellwater were made from conservative tracer measurements. The composition of wellwater ranged from 47% to 100% streamwater with most values above 90%. The time for water to travel from the beginning of the study reach to the wells was approximately three times as great as the travel time in the stream at the same distance down the reach. The three conclusions that can be drawn are (1) water in the stream exchanges extensively with water in the rest of the channel; (2) the interstitial water in the channel gravels achieves almost the same composition as the stream; and (3) under low flow conditions the stream gravels contain a significant portion of the stream volume. Plots of normalized chloride, lithium, and strontium concentrations at three stream sites are included. (Author 's abstract)

Open-File Report↗

USGS1984

Transport and concentration controls for chloride, strontium, potassium and lead in Uvas Creek, a small cobble-bed stream in Santa Clara County, California, U.S.A.: 1. Conceptual model

Stream sediments adsorb certain solutes from streams, thereby significantly changing the solute composition; but little is known about the details and rates of these adsorptive processes. To investigate such processes, a 24-hr. injection of a solution containing chloride, strontium, potassium, sodium and lead was made at the head of a 640-m reach of Uvas Creek in west-central Santa Clara County, California. Uvas Creek is a cobble-bed pool-and-riffle stream draining the eastern slopes of the Santa Cruz Mountains. By September 12, 1973, after a long dry season, Uvas Creek had a low (0.0215 m 3 s −1 average) flow which varied diurnally, from 0.018 to 0.025 m 3 s −1 . Because stream discharge varied while the injection rate was constant, the concentration of tracers (injected solutes), after mixing in the stream, varied inversely with discharge. Chloride, a nonreactive solute, served as a tracer of water movement. Analysis of extensive chloride concentration data at five sites below the injection point during and after the injection demonstrated that there was considerable underflow of water through the stream gravels; however, the extent of underflow varied greatly within the study reach. Pre-injection water, displaced by tracer-laden water percolating through the gravels, diluted tracers in the stream channel, giving the mistaken impression of groundwater inflow at some points. Accurate measurement of total discharge in such streams requires prolonged tracer injection unless a reach can be found where underflow is negligible. Strontium and potassium were adsorbed by the bed sediments to a moderate extent and lead was strongly adsorbed. A high proportion of these metals could be removed by adsorption from percolating underflow because of extensive and intimate contact with bed sediments. After channel clearing following injection cutoff, 51% of the added strontium and 96% of the lead remained in the study reach, whereas only 19% of the chloride remained. Packets of sized sediment, placed in the stream before the experiment and withdrawn during and after the injection, indicated that the strontium absorbed on the 0.42–0.50-mm size sediment appeared to achieve near equilibrium with dissolved strontium within less than 2 hr. whereas 3.4–4.0-mm grains had not reached that stage after 24 hr. The cation-exchange capacity (CEC) of the sediments shows a “bimodal” distribution with grain size. Largest values are in the finest sizes, lower values in the fine-to-medium sand-size range, intermediate values in the coarse- to very coarse-grained sand, and decreasing values with size above very coarse-grained sand. This considerable exchange capacity in coarse-sand to granule-size particles means that a streambed, that has not been infilled with fines to reduce permeability, can be highly reactive and accessible throughout a rather thick sediment layer and hence have a large and available reactive capacity. As stream discharge increases from low flow, the ratio of underflow to channel flow should decrease rapidly with resultant diminution in percent of solutes sorbed within a particular stream reach.

California↗

USGS1984

Transport and concentration controls for chloride, strontium, potassium and lead in Uvas Creek, a small cobble-bed stream in Santa Clara County, California, U.S.A.: 2. Mathematical modeling

Three models describing solute transport of conservative ion species and another describing transport of species which adsorb linearly and reversibly on bed sediments are developed and tested. The conservative models are based on three different conceptual models of the transient storage of solute in the bed. One model assumes the bed to be a well-mixed zone with flux of solute into the bed proportional to the difference between stream concentration and bed concentration. The second model assumes solute in the bed is transported by a vertical diffusion process described by Fick's law. The third model assumes that convection occurs in a selected portion of the bed while the mechanism of the first model functions everywhere. The model for adsorbing species assumes that the bed consists of particles of uniform size with the rate of uptake controlled by an intraparticle diffusion process. All models are tested using data collected before, during and after a 24-hr. pulse injection of chloride, strontium, potassium and lead ions into Uvas Creek near Morgan Hill, California, U.S.A. All three conservative models accurately predict chloride ion concentrations in the stream. The model employing the diffusion mechanism for bed transport predicts better than the others. The adsorption model predicts both strontium and potassium ion concentrations well during the injection of the pulse but somewhat overestimates the observed concentrations after the injection ceases. The overestimation may be due to the convection of solute deep into the bed where it is retained longer than the 3-week post-injection observation period. The model, when calibrated for strontium, predicts potassium equally well when the adsorption equilibrium constant for strontium is replaced by that for potassium.

California↗

USGS1984

Low-flow transport models for conservative and sorbed solutes — Uvas Creek, near Morgan Hill, California

Models describing low-flow transport of conservative (nonreactive) and reactive solutes, which adsorb on the streambed, are developed and tested. Temporary storage within the bed plays an important role in solute movement. Three different models of bed-storage processes are developed for conservative solutes. One model assumes the bed is a well-mixed, nondiffusing, nonreacting zone. Solute flux into the bed is then proportional to the difference between stream and bed-solute concentrations. A second model assumes that solute is transported within the bed by a vertical diffusion process. The bed-solute concentration, which matches the stream concentration at the interface, varies with depth in the bed according to Fick 's law. A third model assumes convection in the downstream direction occurs in certain parts of the bed, while the mechanism of the first model functions elsewhere. Storage of absorbing species is assumed to occur by equilibrium adsorption within streambed particles. Uptake rate is described by an intraparticle diffusion process. Model equations were solved using finite element numerical methods. Models were calibrated using data from a 24-hour injection of conservative chloride and adsorptive Sr ions at Uvas Creek near Morgan Hill, California. All models predict well except for some overestimation by the adsorption model during dieaway.

California↗

USGS1977

A synoptic survey of trace metals in bottom sediments of the Willamette River, Oregon

For nearly half a century the Willamette River in Oregon experienced severe dissolved-oxygen problems related to large loads of organically rich waste waters from industries and municipalities. Since the mid-1950 's dissolved oxygen quality has gradually improved owing to low-flow augmentation, the achievement of basinwide secondary treatment, and the use of other waste-management practices. As a result, summer dissolved-oxygen levels have increased, salmon runs have returned, and the overall effort is widely regarded as a singular water-quality success. To document the improved dissolved-oxygen regimen, the U.S. Geological Survey conducted intensive studies of the Willamette during the summer low-flow seasons of 1973 and 1974. During each summer the mean daily dissolved-oxygen levels were found to be higher than 5 milligrams per liter throughout the river. Because of the basinwide secondary treatment, carbonaceous deoxygenation rates were low. In addition, almost half of the biochemical oxygen demand entering the Willamette was from diffuse (nonpoint) sources rather than outfalls. These results indicated that point-source biochemical oxygen demand was no longer the primary cause of dissolved-oxygen depletion. Instead, the major causes of deoxygenation were nitrification in a shallow ' surface active ' reach below Salem and an anomalous oxygen demand (believed to be primarily of benthal origin) in Portland Harbor. (Woodard-USGS)

Circular↗

USGS1976

Backflushing Filters for Field Processing of Water Samples Prior to Trace-Element Analyses

A portable unit is described for filtering water samples at field sites in such a manner that the filtrate is suitable for analysis not only of major constituents but also of trace elments at the mocrogram-per-liter level. A battery-operated peristaltic pump forces the water sample through medical-grade silicone tubing into and through an all-plastic in-line filter which can be backflushed when sediment clogs the filter membrane. Initial filtration rate exceeds 500 milliliter/minute and, because of the backflushing feature, a total time for filtering high-sediment-bearing waster samples is greatly reduced. (Woodard-USGS)

Water-Resources Investigations Report↗

USGS1976

Solute transport and modeling of water quality in a small stream

An injection of chloride, sodium, and stable strontium was made at a constant rate for 3 hours into Uvas Creek, Santa Clara County, Calif., to determine the mass transport processes in a small stream. Five observation points were selected within a 610-metre reach of the stream below the injection site. Water samples were collected at the observation points during and immediately after the injection. A mathematical model of the stream was obtained by solving analytically and optimally the one-dimensional mass transport equation of the solutes in the stream. Comparison of field results with a simplified mathematical model indicates the dominance of convection in the behavior of sodium and chloride. The concentration of chloride and sodium can be closely simulated by the model. However, strontium cannot be well represented by the simplified model, which contains a first-order decay-type sink.

California↗

USGS1971