Geology topics

Scott J. Kenner

Publications and source records attributed to Scott J. Kenner.

3 recordsLinked to original sources

USGS2014

The atmosphere can be a source of certain water soluble volatile organic compounds in urban streams

Surface water and air volatile organic compound (VOC) data from 10 U.S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water (C w s ) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m - & p -xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long-term method detection levels (LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one-half the LTMDL in water. Six compounds (chloroform, p-isopropyltoluene, methylene chloride, perchloroethene, 1,1,1-trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m - & p -xylene, methyl tert-butyl ether (MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere.

Journal of the American Water Resources Associatio↗

USGS2012

Multivariate statistical approach to estimate mixing proportions for unknown end members

A multivariate statistical method is presented, which includes principal components analysis (PCA) and an end-member mixing model to estimate unknown end-member hydrochemical compositions and the relative mixing proportions of those end members in mixed waters. PCA, together with the Hotelling T 2 statistic and a conceptual model of groundwater flow and mixing, was used in selecting samples that best approximate end members, which then were used as initial values in optimization of the end-member mixing model. This method was tested on controlled datasets (i.e., true values of estimates were known a priori) and found effective in estimating these end members and mixing proportions. The controlled datasets included synthetically generated hydrochemical data, synthetically generated mixing proportions, and laboratory analyses of sample mixtures, which were used in an evaluation of the effectiveness of this method for potential use in actual hydrological settings. For three different scenarios tested, correlation coefficients ( R 2 ) for linear regression between the estimated and known values ranged from 0.968 to 0.993 for mixing proportions and from 0.839 to 0.998 for end-member compositions. The method also was applied to field data from a study of end-member mixing in groundwater as a field example and partial method validation.

Journal of Hydrology↗

USGS2000

Summary of precipitation data for the Black Hills area of South Dakota, water years 1931-98

Long-term precipitation records are sum-marized for the Black Hills area of South Dakota. Precipitation data are available for numerous gaging locations; however, few gages have continuous, long-term records, and periods of missing record are common. Thus, a geographic information system (GIS) utilizing an inverse-distance weighting method was developed to generate spatial precipitation distributions from point precipitation data for the Black Hills area, based on available monthly records. The spatial distributions were used to estimate periods of missing record for all 94 gages considered. The resulting monthly records of measured and estimated precipitation are tabulated for water years 1931-98. Average values for water years 1961-90, which is the period used for calculation of climatic normals, were used to develop an isohyetal map of normal annual precipitation for the Black Hills area. Temporal trends in precipitation for the Black Hills area also were examined. Sustained periods of deficit precipitation occurred during 1931-40 and 1948-61. Sustained periods of surplus precipitation occurred during 1941-47, 1962-68, and 1991-98, with the late 1990's identified as the wettest period since 1931. The driest 30-year period was 1931-60, when annual precipitation averaged 17.17 inches for the study area. The wettest 30-year period was 1969-98, when annual precipitation averaged 19.61 inches. Normal annual precipitation (1961-90) for the study area is 19.06 inches, compared with the long-term (1931-98) annual average of 18.61 inches. Annual extremes for the study area have ranged from 10.22 inches in water year 1936 to 27.39 inches in water year 1995.

Open-File Report↗