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Mark W. Sandstrom

Publications and source records attributed to Mark W. Sandstrom.

52 records · Page 3Linked to original sources
USGS2005

Chemical loading into surface water along a hydrological, biogeochemical, and land use gradient: A holistic watershed approach

Identifying the sources and impacts of organic and inorganic contaminants at the watershed scale is a complex challenge because of the multitude of processes occurring in time and space. Investigation of geochemical transformations requires a systematic evaluation of hydrologic, landscape, and anthropogenic factors. The 1160 km 2 Boulder Creek Watershed in the Colorado Front Range encompasses a gradient of geology, ecotypes, climate, and urbanization. Streamflow originates primarily as snowmelt and shows substantial annual variation. Water samples were collected along a 70-km transect during spring-runoff and base-flow conditions, and analyzed for major elements, trace elements, bulk organics, organic wastewater contaminants (OWCs), and pesticides. Major-element and trace-element concentrations were low in the headwaters, increased through the urban corridor, and had a step increase downstream from the first major wastewater treatment plant (WWTP). Boron, gadolinium, and lithium were useful inorganic tracers of anthropogenic inputs. Effluent from the WWTP accounted for as much as 75% of the flow in Boulder Creek and was the largest chemical input. Under both hydrological conditions, OWCs and pesticides were detected in Boulder Creek downstream from the WWTP outfall as well as in the headwater region, and loads of anthropogenic-derived contaminants increased as basin population density increased. This report documents a suite of potential endocrine-disrupting chemicals in a reach of stream with native fish populations showing indication of endocrine disruption.

Environmental Science & Technology↗
USGS2005

Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center

The hydraulic and geochemical performance of a 366 m long permeable reactive barrier (PRB) at the Denver Federal Center, Denver, Colorado, was evaluated. The funnel and gate system, which was installed in 1996 to intercept and remediate ground water contaminated with chlorinated aliphatic hydrocarbons (CAHs), contained four 12.2 m wide gates filled with zero‐valent iron. Ground water mounding on the upgradient side of the PRB resulted in a tenfold increase in the hydraulic gradient and ground water velocity through the gates compared to areas of the aquifer unaffected by the PRB. Water balance calculations for April 1997 indicate that about 75 % of the ground water moving toward the PRB from upgradient areas moved through the gates. The rest of the water either accumulated on the upgradient side of the PRB or bypassed the PRB. Chemical data from monitoring wells screened down‐gradient, beneath, and at the ends of the PRB indicate that contaminants had not bypassed the PRB, except in a few isolated areas. Greater than 99 % of the CAH mass entering the gates was retained by the iron. Fifty‐one percent of the CAH carbon entering one gate was accounted for in dissolved C 1 and C 2 hydrocarbons, primarily ethane and ethene, which indicates that CAHs may adsorb to the iron prior to being dehalogenated. Treated water exiting the gates displaced contaminated ground water at a distance of at least 3 m downgradient from the PRB by the end of 1997. Measurements of dissolved inorganic ions in one gate indicate that calcite and siderite precipitation in the gate could reduce gate porosity by about 0.35 % per year. Results from this study indicate that funnel and gate systems containing zero‐valent iron can effectively treat ground water contaminated with CAHs. However, the hydrologic impacts of the PRB on the flow system need to be fully understood to prevent contaminants from bypassing the PRB.

Colorado↗
USGS2005

Widespread detection of N, N-diethyl-m-toluamide in U.S. streams: Comparison with concentrations of pesticides, personal care products, and other organic wastewater compounds

One of the most frequently detected organic chemicals in a nationwide study concerning the effects of wastewater on stream water quality conducted in the year 2000 was the widely used insect repellant N , N -diethyl- m -toluamide (DEET). It was detected at levels of 0.02 μg/L or greater in 73% of the stream sites sampled, with the selection of sampling sites being biased toward streams thought to be subject to wastewater contamination (i.e., downstream from intense urbanization and livestock production). Although DEET frequently was detected at all sites, the median concentration was low (0.05 μg/L). The highest concentrations of DEET were found in streams from the urban areas (maximum concentration, 1.1 μg/L). The results of the present study suggest that the movement of DEET to streams through wastewater-treatment systems is an important mechanism that might lead to the exposure of aquatic organisms to this chemical.

Environmental Toxicology and Chemistry↗
USGS2005

Glyphosate, other herbicides, and transformation products in Midwestern streams, 2002

The use of glyphosate has increased rapidly, and there is limited understanding of its environmental fate. The objective of this study was to document the occurrence of glyphosate and the transformation product aminomethylphosphonic acid (AMPA) in Midwestern streams and to compare their occurrence with that of more commonly measured herbicides such as acetochlor, atrazine, and metolachlor. Water samples were collected at sites on 51 streams in nine Midwestern states in 2002 during three runoff events: after the application of pre‐emergence herbicides, after the application of post‐emergence herbicides, and during harvest season. All samples were analyzed for glyphosate and 20 other herbicides using gas chromatography/mass spectrometry or high performance liquid chromatography/mass spectrometry. The frequency of glyphosate and AMPA detection, range of concentrations in runoff samples, and ratios of AMPA to glyphosate concentrations did not vary throughout the growing season as substantially as for other herbicides like atrazine, probably because of different seasonal use patterns. Glyphosate was detected at or above 0.1 μg/1 in 35 percent of pre‐emergence, 40 percent of post‐emergence, and 31 percent of harvest season samples, with a maximum concentration of 8.7 μg/1. AMPA was detected at or above 0.1 μg/1 in 53 percent of pre‐emergence, 83 percent of post‐emergence, and 73 percent of harvest season samples, with a maximum concentration of 3.6 μg/1. Glyphosate was not detected at a concentration at or above the U.S. Environmental Protection Agency's maximum contamination level (MCL) of 700 μg/1 in any sample. Atrazine was detected at or above 0.1 μg/1 in 94 percent of pre‐emergence, 96 percent of post‐emergence, and 57 percent of harvest season samples, with a maximum concentration of 55 μg/1. Atrazine was detected at or above its MCL (3 μg/1) in 57 percent of pre‐emergence and 33 percent of post‐emergence samples.

Illinois, Indiana, Iowa, Kansas, Michigan, Minneso↗
USGS2003

Simplified method for detecting tritium contamination in plants and soil

Cost-effective methods are needed to identify the presence and distribution of tritium near radioactive waste disposal and other contaminated sites. The objectives of this study were to (i) develop a simplified sample preparation method for determining tritium contamination in plants and (ii) determine if plant data could be used as an indicator of soil contamination. The method entailed collection and solar distillation of plant water from foliage, followed by filtration and adsorption of scintillation-interfering constituents on a graphite-based solid phase extraction (SPE) column. The method was evaluated using samples of creosote bush [ Larrea tridentata (Sessé & Moc. ex DC.) Coville], an evergreen shrub, near a radioactive disposal area in the Mojave Desert. Laboratory tests showed that a 2-g SPE column was necessary and sufficient for accurate determination of known tritium concentrations in plant water. Comparisons of tritium concentrations in plant water determined with the solar distillation–SPE method and the standard (and more laborious) toluene-extraction method showed no significant difference between methods. Tritium concentrations in plant water and in water vapor of root-zone soil also showed no significant difference between methods. Thus, the solar distillation–SPE method provides a simple and cost-effective way to identify plant and soil contamination. The method is of sufficient accuracy to facilitate collection of plume-scale data and optimize placement of more sophisticated (and costly) monitoring equipment at contaminated sites. Although work to date has focused on one desert plant, the approach may be transferable to other species and environments after site-specific experiments.

Journal of Environmental Quality↗
USGS2003

Work plan for determining the occurrence of glyphosate, its transformation product AMPA, other herbicide compounds, and antibiotics in midwestern United States streams, 2002

Changes in herbicide use in the Midwestern United States have been substantial over the last 5 years. Most significant is a tripling in the use of glyphosate (N-[phosphonomethyl]glycin). Over this same time period (1997­2001), atrazine use increased by 20 percent and acetochlor use increased by 10 percent, while cyanazine use decreased by 99 percent, alachlor use decreased by 70 percent, and metolachlor use decreased by 55 percent. Previous studies have documented that herbicide flushes occur in midwestern streams during runoff events for several weeks to several months following application, and that herbicide concentrations in midwestern streams during flushing events are related to rates of herbicide use. The objective of this study is to determine the distribution of glyphosate and its primary transformation product aminomethylphosphonic acid (AMPA) in midwestern streams during post-application and harvest-season runoff events. Water samples will be collected in 2002 during two post-herbicide-application runoff events and one harvest-season runoff event from 53 sites on streams in the Midwestern United States. All samples will be analyzed at the U.S. Geological Survey Organic Geochemistry Research Laboratory in Lawrence, Kansas, for glyphosate and 20 other herbicides. Samples will also be analyzed for a glyphosate transformation product (AMPA) and 26 other herbicide transformation products, using GC/MS or HPLC/MS. Selected samples will be analyzed for 36 antibiotics or antibiotic transformational products. Results from this study will represent the first broad-scale investigation of glyphosate and AMPA in U.S. water resources.

Midwest region↗
USGS2003

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of gasoline oxygenates, selected degradates, and BTEX in water by heated purge and trap/gas chromatography/mass spectrometry

A method for determination of the alkyl ethers u sed as gasoline oxygenates [ethyl tert -butyl ether (ETBE), methyl tert -butyl ether (MTBE), diisopropyl ether (DIPE), and tert -amyl methyl ether (TAME)], some of their main degradates [acetone, methyl acetate, tert -butyl alcohol (tBA), and tert -amyl alcohol (tAA)], and BTEX (benzene, toluene, ethylbenzene, and xylenes) at low concentrations (<5 micrograms per liter) in water samples was developed. The compounds are determined using heated extraction to improve purging of polar compounds in a standard gas chromatography/ mass spectrometry (GC/MS) method for volatile compounds. Volatile compounds in this method are extracted (purged) from the sample b y bubbling helium through a 25-mL (milliliter) sample heated at about 65°C. Volatile compounds are trapped on a sorbent and then thermally desorbed into a GC/MS system for identification and quantitation. The calibration range for this method is 0.1 to 200 μg/L (micrograms per liter). Mean gasoline oxygenate recoveries from volatile-grade blank-water samples analyzed at concentrations from 0.5 to 5.0 μg/L were 95 to 105 percent, with relative standard deviations (RSDs) from 1.9 to 3.2 percent. Mean oxygenate degradate recoveries ranged from 88 to 107 percent, with RSDs of 3.2 to 7.4 percent, at concentrations from 1 to 50 μg/ L. Mean BTEX recoveries ranged from 91 to 107 percent, with RSDs of 1.1 to 6.6 percent, at concentrations from 0.5 to 10 μg/L . The method detection limits range from 0.035 to 0.052 μg/L for the gasoline oxygenates, 0.216 to 0.62 μg/L for the oxygenate degradates, and 0.005 to 0.036 μg/L for BTEX. Calculated holding times using American Society for Testing and Materials (ASTM) procedure D 4841-88 indicate that all of the analytes are stable for a minimum of 40 days at pH 2 and pH 7, except for methyl acetate, which is only stable for 7 days at pH 2.

Water-Resources Investigations Report↗
USGS2002

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-A method supplement for the determination of Fipronil and degradates in water by gas chromatography/mass spectrometry

A method for the isolation and detemrination of fipronil and four of its degradates has been developed. This method adapts an analytical method created by the U.S. Geological Survey National Water Quality Laboratory in 1995 for the determination of a broad range of high-use pesticides typically found in filtered natural-water samples. In 2000, fipronil and four of its degradates were extracted, analyzed, and validated using this method. The recoveries for these five compounds in reagent-water samples fortified at 1 microgram per liter (ug/L) avereraged 98 percent. Initial method detection limits averaged 0.0029 ug/L. The performance of these five new compounds is consistent with the performance of the compounds in the initial method, making it possible to include them in addition to the other 41 pesticides and pesticide degradates in the original method.

Open-File Report↗
USGS2001

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory - Determination of moderate-use pesticides and selected degradates in water by C-18 solid-phase extraction and gas chromatography/mass spectrometry

A method for the isolation and analysis of 21 parent pesticides and 20 pesticide degradates in natural-water samples is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase-extraction columns that contain octadecyl-bonded porous silica to extract the analytes. The columns are dried by using nitrogen gas, and adsorbed analytes are eluted with ethyl acetate. Extracted analytes are determined by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 2 micrograms per liter (µg/L) for most analytes. Single-operator method detection limits in reagent-water samples range from 0.00 1 to 0.057 µg/L. Validation data also are presented for 14 parent pesticides and 20 degradates that were determined to have greater bias or variability, or shorter holding times than the other compounds. The estimated maximum holding time for analytes in pesticide-grade water before extraction was 4 days. The estimated maximum holding time for analytes after extraction on the dry solid-phase-extraction columns was 7 days. An optional on-site extraction procedure allows for samples to be collected and processed at remote sites where it is difficult to ship samples to the laboratory within the recommended pre-extraction holding time. The method complements existing U.S. Geological Survey Method O-1126-95 (NWQL Schedules 2001 and 2010) by using identical sample preparation and comparable instrument analytical conditions so that sample extracts can be analyzed by either method to expand the range of analytes determined from one water sample.

Water-Resources Investigations Report↗
USGS1995

Relations between pesticide use and riverine flux in the Mississippi River Basin

In an intensive subcontimental study of pesticides in surface waters of the United States, concentrations of 26 high-use pesticides were measured at nine sites in the Mississippi River basin from May 1991 through March 1992. Calculated total fluxes were combined with agricultural-use data to estimate the percentage of applied pesticide reaching the mouths of the Mississippi River and six major tributaries. For most pesticides, the riverine flux was less than 2% of the mass applied agriculturally. The insecticide diazinon was detected frequently in rivers draining the three basins with the highest population densities, apparently as a result of urban use.

Mississippi River basin↗
USGS1995

U.S. Geological Survey laboratory method for methyl tert-butyl ether and other fuel oxygenates

Methyl tert-butyl ether (MTBE) was found in shallow ground-water samples in a study of 8 urban and 20 agricultural areas throughout the United States in 1993 and 1994 (Squillace and others, 1995, p. 1). The compound is added to gasoline either seasonally or year round in many parts of the United States to increase the octane level and to reduce carbon monoxide and ozone levels in the air. The U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL), near Denver, uses state-of-the-art technology to analyze samples for MTBE as part of the USGS water-quality studies. In addition, the NWQL offers custom analyses to determine two other fuel oxygenates--ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME). The NWQL was not able to obtain a reference standard for tert-amyl ethyl ether (TAEE), another possible fuel oxygenate (Shelley and Fouhy, 1994, p. 63). The shallow ground-water samples were collected as part of the USGS National Water-Quality Assessment Program. These samples were collected from 211 urban wells or springs and 562 agricultural wells sampled by the USGS in 1993 and 1994. The wells were keyed to specific land-use areas to assess the effects of different uses on ground-water quality (Squillace and others, 1995, p. 2). Ground-water samples were preserved on site to pH less than or equal to 2 with a solution of 1:1 hydrochloric acid. All samples were analyzed at the NWQL within 2 weeks after collection. The purpose of this fact sheet is to explain briefly the analytical method implemented by the USGS for determining MTBE and other fuel oxygenates. The scope is necessarily limited to an overview of the analytical method (instrumentation, sample preparation, calibration and quantitation, identification, and preservation of samples) and method performance (reagent blanks, accuracy, and precision).

Fact Sheet↗
USGS1995

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of pesticides in water by C-18 solid-phase extraction and capillary-column gas chromatography/mass spectrometry with selected-ion monitoring

A method for the isolation of 41 pesticides and pesticide metabolites in natural-water samples using C-18 solid-phase extraction and determination by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase extraction columns containing octadecyl-bonded porous silica to extract the pesticides. The columns are dried using carbon dioxide or nitrogen gas, and adsorbed pesticides are removed from the columns by elution with 3.0 milliliters of hexane-isopropanol (3:1). Extracted pesticides are determined by capillary- column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 4 micrograms per liter (g/L) for most pesticides, with the exception of widely used corn herbicides--atrazine, alachlor, cyanazine, and metolachlor--which have upper concentration limits of 20 g/L. Single- operator method detection limits in reagent-water samples range from 0.001 to 0.018 g/L. Average short-term single-operator precision in reagent- water samples is 7 percent at the 0.1- and 1.0-g/L levels and 8 percent at the 0.01-g/L level. Mean recoveries in reagent-water samples are 73 percent at the 0.1- and 1.0-g/L levels and 83 percent at the 0.01-g/L level. The estimated holding time for pesticides after extraction on the solid-phase extraction columns was 7 days. An optional on-site extraction procedure allows for samples to be collected and processed at remote sites where it is difficult to ship samples to the laboratory within the recommended pre-extraction holding time.

Open-File Report↗
USGS1995

Filtration of water-sediment samples for the determination of organic compounds

This report describes the equipment and procedures used for on-site filtration of surface-water and ground-water samples for determination of organic compounds. Glass-fiber filters and a positive displacement pumping system are suitable for processing most samples for organic analyses. An optional system that uses disposable in-line membrane filters is suitable for a specific gas chromatography/mass spectrometry, selected-ion monitoring analytical method for determination of organonitrogen herbicides. General procedures to minimize contamination of the samples include preparing a clean workspace at the site, selecting appropriate sample-collection materials, and cleaning of the equipment with detergent, tap water, and methanol.

Water-Resources Investigations Report↗
USGS1992

Methods of analysis by the U. S. Geological Survey National Water Quality Laboratory-Determination of organonitrogen herbicides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry with selected-ion monitoring

A method for the isolation of organonitrogen herbicides from natural water samples using solid-phase extraction and analysis by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase extraction cartridges containing octadecyl-bonded porous silica to remove the herbicides. The cartridges are dried using carbon dioxide, and adsorbed herbicides are removed from the cartridges by elution with 1.8 milliliters of hexaneisopropanol (3:1). Extracts of the eluants are analyzed by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of at least three characteristic ions. The method detection limits are dependent on sample matrix and each particular herbicide. The method detection limits, based on a 100-milliliter sample size, range from 0.02 to 0.25 microgram per liter. Recoveries averaged 80 to 115 percent for the 23 herbicides and 2 metabolites in 1 reagent-water and 2 natural-water samples fortified at levels of 0.2 and 2.0 micrograms per liter.

Open-File Report↗
USGS1979

Modern biogenic gas-generated craters (sea-floor “pockmarks”) on the Bering Shelf, Alaska

As many as 1,340 small craters per square kilometre cover the sea floor of Norton Sound in the northeastern Bering Sea. The craters are circular pits, 1 to 10 m in diameter and less than 1 m deep, observed on sonographs over 20,000 km 2 of northern Norton Sound sea floor. Craters typically are associated with acoustic anomalies, near-surface peaty mud, and gas-charged sediment. The peaty mud is a thick (>1.5 m), nonmarine pre-Holocene deposit that is now covered by a 1- to 3-m-thick layer of Holocene marine mud in the area of the craters. The peaty mud (2% to 8% organic carbon) contains abundant biogenic methane [C 1 /(C 2 + C 3 ) = 256 to 7,669] with carbon isotope (δ 13 C) values of −69‰ to −75‰- Decomposition of organic debris in the peaty mud apparently charges the mud with gas. The peaty and gassy zones attenuate sound waves and cause acoustic anomalies on high-resolution seismic profiles in the area with craters. The craters are forming now, as shown by the disruption of modern ice gouges by the craters. In the absence of storms, the gas apparently is trapped in the peaty mud in a saturated state by the cover of Holocene mud. Periodically, possibly during storms, the gas escapes through the thin Holocene cover and forms craters.

Alaska↗