Geology topics

E.R. Bayless

Publications and source records attributed to E.R. Bayless.

5 recordsLinked to original sources

USGS2012

The role of efflorescent sulfate salts in Indiana’s mine water quality

Efflorescent sulfate salts (ESS), which form from evaporating acid mine drainage and occur in a wide variety of environments, can significantly alter water quality and are, therefore, important considerations for remediation strategies at coal refuse sites. Many ESS, including melanterite, rozenite, siderotil, copiapite, halotrichite, coquimbite, epsomite, potash alum, and gypsum, are known to occur in Indiana. Because they build up on the gob-pile surface during dry periods and release acidity and metals in storm flushes, it is essential to understand the mineralogical and geochemical parameters that control ESS formation and dissolution in mine settings. The Friar Tuck site, in southwestern Indiana, is an ideal location for demonstrating the role of ESS in the generation of acid mine drainage and is included as a case study in this report. Examination of two gob piles at the site (northwest and southeast), in the same setting but with different mineralogies and depositional and reclamation histories, provides a unique opportunity to consider the transferability of lessons learned about the ESS between different sites. Hydraulic and chemical data, including data on aqueous and solid states (coal refuse and ESS), were collected from streams (adjacent to the gob piles and further downstream), seeps, surface runoff, and saturated and unsaturated groundwater at the northwest and southeast gob piles during 1988–89 and 1990–92, respectively. Samples were analyzed in the field for bulk indicators and in a laboratory (Indiana Geological Survey, Geochemistry Section) for concentrations of major and trace elements. Values of pH and specific conductance at the southeast gob pile indicated a trend of declining water quality with duration of the dry season, followed by dilution and improved water quality during the wet season; similar observations were made at the northwest gob pile. Concentrations of key water-quality indicators for the northwest and southeast gob piles show that acidity and concentrations of sulfate and iron are notably lower in the surface runoff and groundwater in saturated and unsaturated refuse at the southeast gob pile compared to the northwest gob pile. The dissolution of ESS is likely the cause for the decrease in water quality at both gob piles, but it has a greater effect at the northwest gob pile. The results of this study indicate that some generalizations about the effect of ESS on water quality (for example, the conditions that favor the precipitation of specific ESS; the development of acidic, metal-rich drainage; and so on) can be transferred from one coal-waste site to another. However, the specific geochemistry of the gob pile, the age and history of refuse, the source rock, and the coal-processing and reclamation activities at the specific site will determine the extent to which the processes described in this and other papers can be applied to unstudied gob piles.

Indiana↗

USGS2011

Accuracy of flowmeters measuring horizontal groundwater flow in an unconsolidated aquifer simulator.

Borehole flowmeters that measure horizontal flow velocity and direction of groundwater flow are being increasingly applied to a wide variety of environmental problems. This study was carried out to evaluate the measurement accuracy of several types of flowmeters in an unconsolidated aquifer simulator. Flowmeter response to hydraulic gradient, aquifer properties, and well-screen construction was measured during 2003 and 2005 at the U.S. Geological Survey Hydrologic Instrumentation Facility in Bay St. Louis, Mississippi. The flowmeters tested included a commercially available heat-pulse flowmeter, an acoustic Doppler flowmeter, a scanning colloidal borescope flowmeter, and a fluid-conductivity logging system. Results of the study indicated that at least one flowmeter was capable of measuring borehole flow velocity and direction in most simulated conditions. The mean error in direction measurements ranged from 15.1 degrees to 23.5 degrees and the directional accuracy of all tested flowmeters improved with increasing hydraulic gradient. The range of Darcy velocities examined in this study ranged 4.3 to 155 ft/d. For many plots comparing the simulated and measured Darcy velocity, the squared correlation coefficient (r 2 ) exceeded 0.92. The accuracy of velocity measurements varied with well construction and velocity magnitude. The use of horizontal flowmeters in environmental studies appears promising but applications may require more than one type of flowmeter to span the range of conditions encountered in the field. Interpreting flowmeter data from field settings may be complicated by geologic heterogeneity, preferential flow, vertical flow, constricted screen openings, and nonoptimal screen orientation.

Ground Water Monitoring and Remediation↗

USGS2008

Influences of the unsaturated, saturated, and riparian zones on the transport of nitrate near the Merced River, California, USA

Transport and transformation of nitrate was evaluated along a 1-km groundwater transect from an almond orchard to the Merced River, California, USA, within an irrigated agricultural setting. As indicated by measurements of pore-water nitrate and modeling using the root zone water quality model, about 63% of the applied nitrogen was transported through a 6.5-m unsaturated zone. Transport times from recharge locations to the edge of a riparian zone ranged from approximately 6 months to greater than 100 years. This allowed for partial denitrification in horizons having mildly reducing conditions, and essentially no denitrification in horizons with oxidizing conditions. Transport times across a 50-100-m-wide riparian zone of less than a year to over 6 years and more strongly reducing conditions resulted in greater rates of denitrification. Isotopic measurements and concentrations of excess N2 in water were indicative of denitrification with the highest rates below the Merced River. Discharge of water and nitrate into the river was dependent on gradients driven by irrigation or river stage. The results suggest that the assimilative capacity for nitrate of the groundwater system, and particularly the riverbed, is limiting the nitrate load to the Merced River in the study area. ?? Springer-Verlag 2007.

Hydrogeology Journal↗

USGS2008

Pesticide fate and transport throughout unsaturated zones in five agricultural settings, USA

P esticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected in soil water during the 2004 growing season, and degradates were generally more abundant than parent compounds. Metolachlor and atrazine were applied at a Nebraska site the same year as sampling, and focused recharge coupled with the short time since application resulted in their movement in the unsaturated zone 9 m below the surface. At other sites where the herbicides were applied 1 to 2 yr before sampling, only degradates were found in soil water. Transformations of herbicides were evident with depth and during the 4-mo sampling time and reflected the faster degradation of metolachlor oxanilic acid and persistence of metolachor ethanesulfonic acid. The fraction of metolachlor ethanesulfonic acid relative to metolachlor and metolachlor oxanilic acid increased from 0.3 to > 0.9 at a site in Maryland where the unsaturated zone was 5 m deep and from 0.3 to 0.5 at the shallowest depth. The flux of pesticide degradates from the deepest sites to the shallow ground water was greatest (3.0–4.9 μmol m −2 yr −1 ) where upland recharge or focused flow moved the most water through the unsaturated zone. Flux estimates based on estimated recharge rates and measured concentrations were in agreement with fluxes estimated using an unsaturated-zone computer model (LEACHM).

Journal of Environmental Quality↗

USGS2005

Atrazine retention and degradation in the vadose zone at a till plain site in central Indiana

The vadose zone was examined as an environmental compartment where significant quantities of atrazine and its degradation compounds may be stored and transformed. The vadose zone was targeted because regional studies in the White River Basin indicated a large discrepancy between the mass of atrazine applied to fields and the amount of the pesticide and its degradation compounds that are measured in ground and surface water. A study site was established in a rotationally cropped field in the till plain of central Indiana. Data were gathered during the 1994 growing season to characterize the site hydrogeology and the distribution of atrazine, desethylatrazine, deisopropylatrazine, didealkylatrazine and hydroxyatrazine in runoff, pore water, and ground water. The data indicated that atrazine and its degradation compounds were transported from land surface to a depth of 1.5 m within 60 days of application, but were undetected in the saturated zone at nearby monitoring wells. A numerical model was developed, based on the field data, to provide information about processes that could retain and degrade atrazine in the vadose zone. Simulations indicated that evapotranspiration is responsible for surface directed soil-moisture flow during much of the growing season. This process causes retention and degradation of atrazine in the vadose zone. Increased residence time in the vadose zone leads to nearly complete transformation of atrazine and its degradation products to unquantified degradation compounds. As a result of mascropore flow, small quantities of atrazine and its degradation compounds may reach the saturated zone.

Indiana↗