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John T. Turk

Publications and source records attributed to John T. Turk.

At least 19 recordsLinked to original sources
USGS2010

Processes controlling the chemistry of two snowmelt‐dominated streams in the Rocky Mountains

Time‐intensive discharge and chemical data for two alpine streams in the Loch Vale watershed, Colorado, were used to identify sources of runoff, flow paths, and important biogeochemical processes during the 1992 snowmelt runoff season. In spite of the paucity of soil cover the chemical composition of the streams is regulated much as in typical forested watersheds. Soils and other shallow groundwater matrices such as boulder fields appear to be more important in controlling surface‐water chemistry than their abundance would indicate. The chemical composition of the major source waters (usually thought of as end‐members whose chemical composition is relatively constant over time) changes at the same time that their mixing ratio in streams changes, confounding use of end‐member mixing models to describe stream‐water chemistry. Changes in the chemical composition of these source waters are caused by the ionic pulse of solutes from the snowpack and the small size of the shallow groundwater reservoir compared to the volume of snowmelt passing through it. The brief hydrologic residence time in the shallow groundwater indicates that concentrations of most dissolved constituents of stream water were controlled by fast geochemical processes that occurred on timescales of hours to days, rather than slower processes such as weathering of primary minerals. Differences in the timing of snowmelt‐related processes between different areas of the watershed also affect the stream‐water chemical composition. Cirque lakes affect discharge and chemical composition of one of the streams; seasonal control on stream‐water NO 3 and SiO 2 concentrations by diatom uptake in the lakes was inferred. Elution of acidic waters from the snowpack, along with dilution of base cations originating in shallow groundwater, caused episodes of decreased acid‐neutralizing capacity in the streams, but the streams did not become acidic.

Colorado↗
USGS2010

Response of lake chemistry to changes in atmospheric deposition and climate in three high-elevation wilderness areas of Colorado

Trends in precipitation chemistry and hydrologic and climatic data were examined as drivers of long-term changes in the chemical composition of high-elevation lakes in three wilderness areas in Colorado during 1985–2008. Sulfate concentrations in precipitation decreased at a rate of −0.15 to −0.55 μeq/l/year at 10 high-elevation National Atmospheric Deposition Program stations in the state during 1987–2008 reflecting regional reductions in SO 2 emissions. In lakes where sulfate is primarily derived from atmospheric inputs, sulfate concentrations also decreased although the rates generally were less, ranging from −0.12 to −0.27 μeq/l/year. The similarity in timing and sulfur isotopic data support the hypothesis that decreases in atmospheric deposition are driving the response of high-elevation lakes in some areas of the state. By contrast, in lakes where sulfate is derived primarily from watershed weathering sources, sulfate concentrations showed sharp increases during 1985–2008. Analysis of long-term climate records indicates that annual air temperatures have increased between 0.45 and 0.93°C per decade throughout most mountainous areas of Colorado, suggesting climate as a factor. Isotopic data reveal that sulfate in these lakes is largely derived from pyrite, which may indicate climate warming is preferentially affecting the rate of pyrite weathering.

Colorado↗
USGS2009

Rocky Mountain Snowpack Physical and Chemical Data for Selected Sites, 1993-2008

The Rocky Mountain Snowpack program established a network of snowpack-sampling sites in the Rocky Mountain region from New Mexico to Montana to monitor the chemical content of snow to help in the understanding of the effects of atmospheric deposition to this region. The U.S. Geological Survey, in cooperation with the National Park Service, the USDA Forest Service, Teton County in Wyoming, Rio Blanco County in Colorado, Pitkin County in Colorado, and others, collected and analyzed snowpack samples annually for 48 or more sites in the Rocky Mountain region during 1993-2008. Forty-eight of the 162 snow-sampling sites have been sampled annually since 1993. Data include acid-neutralization capacity, specific conductance, pH, hydrogen ion concentrations, dissolved concentrations of major constituents (calcium, magnesium, sodium, potassium, ammonium, chloride, sulfate, and nitrate), dissolved organic carbon concentrations, snow/ water equivalent, snow depth, stable sulfur isotope ratios, total mercury concentrations (beginning in 2001), and ionic charge balance. Quality-assurance data for field and laboratory blanks and field replicates for individual years (1993-2008) also are included.

Data Series↗
USGS2008

Response of Ned Wilson Lake watershed, Colorado, to changes in atmospheric deposition of sulfate

The Ned Wilson Lake watershed responds directly and rapidly to changes in precipitation inputs of sulfate, which has important implications for effects of acid deposition on the aquatic system. Chemistry at three precipitation collection sites and three watershed sites (a pond, a lake, and a spring) has been monitored in and near the Flattops Wilderness Area in northwestern Colorado beginning in 1981–1983. Bulk snowpack concentration of sulfate in the watershed and volume-weighted annual mean concentration of sulfate in precipitation at two nearby sites generally decreased from 1981 to 1985, were small through 1987, and increased in 1988–1989. Changes in concentration of sulfate at the watershed sites are controlled by precipitation inputs. Responsiveness of the individual sites was dependent on their position along the hydrologic flow path. The fastest response was in the pond, which has a hydrologic residence time of less than 1 year; over 90% of the variance in concentration of sulfate in the pond was explained by changes in concentration in precipitation. The lake has a hydrologic residence time of 1 to 4 years; a regression model of the concentration of sulfate in the lake, as a function of the concentration in the lake during the previous year and the concentration in precipitation, explained 87% of the variance in concentration of sulfate in the lake. The hydrologic response time of the spring is unknown; it was not responsive to changes in concentration of sulfate in precipitation. The recent increase of sulfate concentration in precipitation and in the pond and lake is evidence for a rapid rather than a delayed response, which could not be determined when only a decreasing trend in sulfate concentration was reported in 1982–1987. Watersheds of this type are sensitive to acidification (acid-neutralizing capacity less than 60 μeq L −1 ), and these results indicate conservative behavior of sulfate. This is important in predicting effects of future changes in atmospheric deposition, which could potentially be caused by anthropogenic emissions or climatic change.

Colorado↗
USGS2002

Comparison of snowpack and winter wet-deposition chemistry in the Rocky Mountains, USA: Implications for winter dry deposition

Depth-integrated snowpack chemistry was measured just prior to maximum snowpack depth during the winters of 1992-1999 at 12 sites co-located with National Atmospheric Deposition Program/National Trend Network (NADP/NTN) sites in the central and southern Rocky Mountains, USA. Winter volume-weighted mean wet-deposition concentrations were calculated for the NADP/NTN sites, and the data were compared to snowpack concentrations using the paired t-test and the Wilcoxon signed-rank test. No statistically significant differences were indicated in concentrations of SO42- or NO3- (p>0.1). Small, but statistically significant differences (p???0.03) were indicated for all other solutes analyzed. Differences were largest for Ca2+ concentrations, which on average were 2.3??eql-1 (43%) higher in the snowpack than in winter NADP/NTN samples. Eolian carbonate dust appeared to influence snowpack chemistry through both wet and dry deposition, and the effect increased from north to south. Dry deposition of eolian carbonates was estimated to have neutralized an average of 6.9??eql-1 and a maximum of 12??eql-1 of snowpack acidity at the southernmost sites. The good agreement between snowpack and winter NADP/NTN SO42- and NO3- concentrations indicates that for those solutes the two data sets can be combined to increase data density in high-elevation areas, where few NADP/NTN sites exist. This combination of data sets will allow for better estimates of atmospheric deposition of SO42- and NO3- across the Rocky Mountain region.

Atmospheric Environment↗
USGS2002

Use of natural 35 S to trace sulphate cycling in small lakes, Flattops Wilderness Area, Colorado, U.S.A.

Measurements of the cosmogenically-produced 35 S, a radioisotope of sulphur (t 1/2 = 87 days), are reported for the Ned Wilson Lake watershed in Colorado. The watershed contains two small lakes and a flowing spring presumed to be representative of local ground water. The watershed is located in the Flattops Wilderness Area and the waters in the system have low alkalinity, making them sensitive to increases in acid and sulphate deposition. Time series of 35 S measurements were made during the summers of 1995 and 1996 (July–September) at all three sites. The system is dominated by melting snow and an initial concentration of 16–20 mBq L -1 was estimated for snowmelt based on a series of snow samples collected in the Rocky Mountains. The two lakes had large initial 35 S concentrations in July, indicating that a large fraction of the lake water and sulphate was introduced by meltwater from that year's snowpack. In 1995 and 1996, 35 S concentrations decreased more rapidly than could be accounted for by decay, indicating that other processes were affecting 35 S concentrations. The most likely explanation is that exchange with sediments or the biota was removing 35 S from the lake and replacing it with older sulphate devoid of 35 S. In September of 1995 and 1996, 35 S concentrations increased, suggesting that atmospheric deposition is important in the sulphate flux of these lakes in late summer. Sulphur-35 concentrations in the spring water were highly variable but never higher than 3.6 mBq L -1 and averaged 2 mBq L -1 . Using a simple mixing model, it was estimated that 75% of the spring water was derived from precipitation of previous years.

Water, Air, and Soil Pollution: Focus↗
USGS2002

Rocky Mountain snowpack chemistry network: History, methods, and the importance of monitoring mountain ecosystems

Because regional-scale atmospheric deposition data in the Rocky Mountains are sparse, a program was designed by the U.S. Geological Survey to more thoroughly determine the quality of precipitation and to identify sources of atmospherically deposited pollution in a network of high-elevation sites. Depth-integrated samples of seasonal snowpacks at 52 sampling sites, in a network from New Mexico to Montana, were collected and analyzed each year since 1993. The results of the first 5 years (1993–97) of the program are discussed in this report. Spatial patterns in regional data have emerged from the geographically distributed chemical concentrations of ammonium, nitrate, and sulfate that clearly indicate that concentrations of these acid precursors in less developed areas of the region are lower than concentrations in the heavily developed areas. Snowpacks in northern Colorado that lie adjacent to both the highly developed Denver metropolitan area to the east and coal-fired powerplants to the west had the highest overall concentrations of nitrate and sulfate in the network. Ammonium concentrations were highest in northwestern Wyoming and southern Montana.

Rocky Mountains↗
USGS2000

Timescales for migration of atmospherically derived sulphate through an alpine/subalpine watershed, Loch Vale, Colorado

Sulphur 35, a cosmogenically produced radioisotope with a short half‐life (87 days), was measured in snowpack during 1993–1997 and at four locations within the Loch Vale watershed during 1995–1997. The four sites include the two main drainages in the watershed, Andrews Creek and Icy Brook, a small south facing catchment flowing into Andrews Creek (Andrews Spring 1), and a similar north facing catchment flowing out of a scree field into Icy Brook (Spring 19). Concentrations ranged from a high of almost 50 mBq/L for a sample from Spring 19 in June 1996 to a concentration near the detection limit for a sample from Andrews Creek in April 1997. Sulphur 35 concentrations were normalized to sulphate (as mBq/mg SO 4 −2 ) and were decay‐corrected to a Julian day of 90 (April 1) for each year. Snowpack had the highest 35 S concentration with an average concentration of 53 mBq/mg SO 4 −2 . Concentrations in the streams were much lower, even when corrected for decay relative to JD 90. The large 35 S concentrations found in Spring 19 were the result of increases in concentration due to sublimation and/or evapotranspiration and were lower than snowpack when normalized to sulphate. Using 35 S concentrations found in snowpack as of JD 90 as a beginning concentration, the fraction of sulphate in streamflow that was derived from atmospheric deposition within the prior water year was estimated. For Icy Brook and Andrews Creek the fraction of the sulphate in streamflow derived from that year's snowpack and precipitation was low prior to the beginning of the main spring melt, reached a maximum during the period of maximum flow, and decreased as the summer progressed. A calculation of the seasonal flux indicated that about 40% of the sulphate that flowed out of the watershed was derived from atmospheric sulphate deposited during the previous year. This suggests that more than half of the sulphate deposited in the watershed by atmospheric processes during the previous year was removed during the following summer. Thus sulphate retention in alpine watersheds like Loch Vale is very limited, and changes in sulphate deposition should be quickly reflected in stream chemistry.

Colorado↗
USGS1999

Environmental characteristics and water quality of hydrologic benchmark network stations in the Eastern United States, 1963-95

The information in this report was compiled to aid in the application and interpretation of historical water-quality data collected as part of the U.S. Geological Survey Hydrologic Benchmark Network program, which was established in 1963 to provide long-term measurements of streamflow and water quality in areas that are minimally affected by human activities. This report describes the environmental characteristics and water quality at 16 benchmark basins in the Eastern United States. In most of the basins, stream-water chemistry seems to be controlled by the interaction of acidic precipitation with the underlying soils and bedrock. Land use had a minimal effect on stream-water chemistry at most of the gaging stations.

Circular↗
USGS1999

Environmental characteristics and water quality of hydrologic benchmark network stations in the Midwestern United States, 1963-95

This report describes the environmental characteristics and water quality at 14 benchmark basins in the Midwestern United States. The information in this report was compiled to aid in the application and interpretation of historical water-quality data collected by the U.S. Geological Survey Hydrologic Benchmark Network program. The streams discussed in this report drain either forested areas or grasslands with a variety of land-use activities that range from recreational use, timber harvesting, and military training on publicly owned land to agriculture and residential development on privately owned land.

Circular↗
USGS1997

Strontium 87/strontium 86 as a tracer of mineral weathering reactions and calcium sources in an alpine/subalpine watershed, Loch Vale, Colorado

Sr isotopic ratios of atmospheric deposition, surface and subsurface water, and geologic materials were measured in an alpine/subalpine watershed to characterize weathering reactions and identify sources of dissolved Ca in stream water. Previous studies have noted an excess of Ca in stream water above that expected from stoichiometric weathering of the dominant bedrock minerals. Mixing calculations based on 87 Sr/ 86 Sr indicate that on an annual basis, 26 ± 7% of Ca export in streams is atmospherically derived, 23 ± 1% is from weathering of plagioclase, and the remainder is from weathering of calcite present in trace amounts in the bedrock. A potential source of error when applying Sr isotopes in catchment studies is determination of the 87 Sr/ 86 Sr of Sr released by mineral weathering, which is complicated by the wide range of mineral isotopic compositions, particularly in older rocks, and the variable rates at which the minerals weather. In this study, base-flow stream chemistry was used to represent the 87 Sr/ 86 Sr of Sr derived from mineral weathering because it effectively integrates the potentially variable isotopic composition of Sr released by weathering in the alpine environment.

Colorado↗
USGS1983

An evaluation of trends in the acidity of precipitation and the related acidification of surface water in North America

The acidity of precipitation in the Northeastern United States and Southeastern Canada has increased in the past, probably as a result of anthropogenic emissions. The increase in New England and New York occurred primarily before the mid-1950's. Since the mid1960's, there has been no significant change in the acidity of precipitation in this region; however, sulfate concentrations have decreased and nitrate concentrations may have increased. The time of initial acidification in Southeastern Canada is not known because of a lack of historical data. In the Southeastern United States, the evaluation of whether precipitation has been acidified is complicated by meager data. The available data show that precipitation is more acidic than would be expected for sites unaffected by anthropogenic emissions. In addition, comparison of recent data with the meager historical data suggests, but does not unambiguously prove, increased acidification since the 1950's. In the Western United States, available data indicate that precipitation at individual sites has been acidified by anthropogenic emissions. The acidification generally has been attributable to localized sources, and the time of initial acidification is undefined. Acidification of lakes and streams in the Northeastern United States has occurred in a time frame compatible with the hypothesis that acidification of precipitation was the cause. The acidification of surface waters appears to have occurred before the mid- to late 1960's. In Southeastern Canada, the best-documented cases of acidified lakes point to localized sources of acidic emissions as the cause. Sparse evidence of recent regional acidification of lakes and streams exists, but evidence for acidification of precipitation as the cause is largely lacking. In the Southeastern United States, most data on acidification of surface waters are ambiguous, and in the West, most of the data reflect local conditions. However, recent analysis of a national network of remote stream sampling stations indicates that, since the mid- to late 1960's, sulfate concentrations have increased in the Southeast and the West, with a concurrent decrease in alkalinity. Additional work is needed to test the hypothesis that regional acidification of surface waters is occurring in the Southeastern and Western United States.

Water Supply Paper↗
USGS1982

Water-quality characteristics of six small, semiarid watersheds in the Green River coal region of Colorado

Analysis of major and trace constituents in streams flowing through six semiarid watersheds indicates that the stream chemistry is characterized by saturation with respect to common carbonate minerals (calcium, magnesium, iron, manganese, and lead). The solubility of the carbonate minerals may be a major control on the absolute and relative concentrations of calcium, magnesium, bicarbonate, iron, manganese, and lead; however, other mechanisms probably control the concentrations of cadmium and zinc. Statistical analyses indicate that the mean concentrations of the major ions in the two climatic areas studied are significantly (P=0.05) different from one another, with larger mean concentrations in the more arid area. Trace-metal concentrations were similar from one area to another and indistinguishable from site to site (P=0.05) for lead, cadmium, and zinc. Linear regressions of major ion concentration to specific conductance are similar in both areas for sodium, bicarbonate, sulfate, and chloride. Results of the study may be useful in providing a first approximation of stream chemistry in other watersheds with the same geologic setting, determining watersheds with similar geochemical controls, and determining future changes in stream chemistry in the watersheds studied. (USGS)

Water-Resources Investigations Report↗
USGS1981

Relationship of water quality of Hudson River, New York, during peak discharges to geologic characteristics of contributing subbasins

Water samples from two Hudson River floods in 1977--one originating mainly in shale subbasins that produce high sediment loads, the other in soil-poor, crystalline rock terrane that yields little sediment--were analyzed to evaluate the relationship of iron, manganese, lead, phosphorus, and polychlorinated biphenyls (PCB's) to suspended-sediment concentration. During the flood of high sediment discharge, ratios for all substances studied except PCB 's reflected their concentration within the basin regolith. During the flood of smaller magnitude, from the low-sediment crystalline terrane, however, only the ratio for iron correlated with predicted concentrations in the basin, which suggests that the chemical constituents studied were contributed principally from other sources, possibly anthropogenic sources. High lead concentrations in the low-sediment flood were derived from an unidentified, basinwide source whose contribution was relatively insignificant during the flood from the shale area. (USGS)

Water-Resources Investigations Report↗
USGS1981

Polychlorinated biphenyl transport in the Hudson River, New York

Polychlorinated biphenyls (PCB's) have been entering the Hudson River estuary since 1951. Concentration and loading of PCB 's in the river below Waterford, N.Y., are controlled at present by resuspension of sediments containing these substances; therefore , until the amount of PCB 's in the sediments is significantly lowered, reduction of point-source PCB discharge from the present rate of 0.4 kilograms per day will produce no more than a 10% reduction in loading to the river. Potential concentrations of PCB 's in solution and suspension in the river can be predicted by a simple model for mixing and dilution. From a known range of PCB influent rates, total PCB loading to the Hudson River from above Waterford is shown to be between 2,000 and 12,000 kilograms per year. (USGS)

Water-Resources Investigations Report↗
USGS1979

Appraisal of ground water in the vicinity of the Leadville drainage tunnel, Lake County, Colorado

Ground water in the Leadville mining district occurs in granite, quartzite, limestone, sandstone, porphyry dikes, and unconsolidated material. These rocks form a single aquifer system because the formations are hydraulically connected through contact, mine workings, faulting, and fracturing. The aquifer is recharged by precipitation and water moves toward California Gulch and probably toward Evans Gulch, in the drainage basin of the Arkansas River. The Leadville drainage tunnel was constructed from 1943 to 1945 and later extended during 1950 to 1952, in order to drain the mine workings. Discharge from the tunnel lowered water levels 30 to 96 feet in mine shafts from 1944 to 1951. Installation of an impervious plug in the tunnel has been proposed in order to reduce the discharge of water containing objectionable concentrations of trace metals into the East Fork Arkansas River. The proposed plug would reduce the discharge from the tunnel, cause water levels east of the town of Leadville to rise, flood some mine workings, and increase ground-water discharge to California Gulch. However, the proposed plug is not expected to cause water levels in Leadville to rise substantially, but more current and detailed data are needed to verify this. Discharge from the Leadville drainage tunnel is probably a mixture of water in equilibrium with carbonate aquifer materials from the mineralized zone, water acidified by the localized oxidation of pyrite from the mineralized zone, and water nearly saturated with calcite from the glacial mantle. Based on limited data, water from the carbonate mineral deposits has a pH of about 7.0 and concentrations of manganese of about 1,800 micrograms per liter and zinc concentrations of about 13,000 micrograms per liter. (USGS)

Open-File Report↗
USGS1978

Mallets Creek Marsh, Lake Champlain: A plant-nutrient study

Nitrogen and phosphorus dissolved in the interstitial water of Mallets Creek Marsh sediments supply about 42 percent of the nitrogen and about 9 percent of the phosphorus used by rooted macrophytes within the marsh. These percentages may become larger during middle and late summer, when water inflow to the marsh is reduced and the supply of dissolved nitrogen and phosphorus is diminished. Fluctuations in water-surface level alternately saturate and partially dewater sediments between approximately 98.5 feet and 93.5 feet above mean sea level. Repeated water-level declines to below 98.5 feet through lake-level regulation in spring or early summer could transport interstitial nitrogen and phosphorus from the marshes to Lake Champlain. This would decrease the growth of rooted macrophytes within the marsh and promote eutrophication of the lake.

Vermont↗