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James A. Tindall

Publications and source records attributed to James A. Tindall.

9 recordsLinked to original sources
USGS2016

Transport of atrazine versus bromide and δO18 in sand

The objective of this research was to determine the process of atrazine transport compared to bromide and δO 18 transport in sands near Denver. Three 1.5 × 2 × 1.5-m plots were installed and allowed to equilibrate for 2 years before research initiation and were instrumented with 1.5 × 2-m zero-tension pan lysimeters installed at 1.5-m depths. Additionally, each plot was instrumented with suction lysimeters, tensiometers, time domain reflectometry (TDR) moisture probes, and thermocouples (to measure soil temperature) at 15-cm depth increments. All plots were enclosed with a raised frame (of 8-cm height) to prevent surface runoff. During the 2-year period before research began, all suction and pan lysimeters were purged monthly and were sampled for fluids immediately prior to atrazine and KBr application to obtain background concentrations. Atrazine illustrated little movement until after a significant rainfall event, which peaked concentrations at depths of about 90 to 135 cm. Both Br − and δO 18 moved rapidly through the soil, probably owing to soil porosity and anion exclusion for Br − . Concentrations of atrazine exceeding 5.0 μL −1 were observed with depth (90 to 150 cm) after several months. It appears that significant rainfall events were a key factor in the movement of atrazine in the sand, which allowed the chemicals to move to greater depths and thus avoid generally found biodegradation processes.

Water, Air, & Soil Pollution↗
USGS2016

Transport of atrazine and dicamba through silt and loam soils

The objectives of this research were to determine the role of preferential flow paths in the transport of atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) and dicamba (3-6-dichloro-2-methoxybenzoic acid) through silt and loam soils overlying the High Plains aquifer in Nebraska. In a previous study, 3 of 6 study areas demonstrated high percentages of macropores; those three areas were used in this study for analysis of chemical transport. As a subsequent part of the study, 12 intact soil cores (30-cm diameter by 40-cm height), were excavated sequentially, two from each of the following depths: 0-40cm and 40-80cm. These cores were used to study preferential flow characteristics using dye staining and to determine hydraulic properties. Two undisturbed experimental field plots, each with a 3-m2 surface area, were installed in three study areas in Nebraska. Each was instrumented with suction lysimeters and tensiometers at depths of 10cm to 80cm in 10-cm increments. Additionally, each plot was planted with corn (Zea mays). A neutron probe access tube was installed in each plot to determine soil w ater content at 15-cm intervals. All plots were enclosed w ith a raised frame (of 8-cm height) to prevent surface runoff. All suction lysimeters were purged monthly for three months and were sampled immediately prior to pre-plant herbicide application to obtain background chemical concentrations. Atrazine and dicamba moved rapidly through the soil, but only after a heavy rainfall event, probably owing to the presence of preferential flow paths and lack of microbial degradation in these soil areas. Staining of laboratory cores showed a positive correlation between the percent area stained by depth and the subsequent breakthrough of Br- in the laboratory and leaching of field-applied herbicides owing to large rainfall events. Suction lysimeter samples in the field showed increases in concentrations of herbicides at depths where laboratory data indicated greater percentages of what appeared to be preferential flow paths. Concentrations of atrazine and dicamba exceeding 0.30 and 0.05µg m1-1 were observed at depths of 10-30cm and 50-70cm after two months following heavy rainfall events. It appears from the laboratory experiment that preferential flow paths were a significant factor in transport of atrazine and dicamba.

Nebraska↗
USGS2014

Variables that affect agricultural chemicals in groundwater in Nebraska

Agricultural chemicals from nonpoint sources in groundwater are present in the major provinces of the High Plains aquifer in Nebraska. Nitrate and triazine-herbicide concentrations in groundwater were assessed to establish preliminary relations between these constituents and selected hydrogeologic, climatic, and land-use variables. Also, macropore flow paths were measured in an attempt to delineate their contribution to non-point source pollution from the study areas. Water from 82 wells in six study areas was analyzed for nitrate; water from 57 of the 82 wells was analyzed for triazine herbicides. Twenty-one independent variables were identified that could potentially affect chemical concentrations in groundwater. Data for 9 of 21 independent variables suspected of affecting concentrations of nitrate and triazine herbicides in groundwater were collected from the well sites. The nine variables and their measured ranges were hydraulic gradient, 0.0006–0.0053; hydraulic conductivity, 1.5–45.4 m (5–149 ft) per day; specific discharge, 0.004–0.091 m (0.0128–0.2998 ft) per day; depth to water, 0.91–76 m (3–250 ft); well depth, 12–168 m (40–550 ft); annual precipitation, 30–100 cm (12.0–39.3 in.); soil permeability, 1.9–23 cm (0.76–9.0 in.); irrigation-well density, 0–8 irrigation wells per 2.59 km 2 (1 square mile); and annual nitrogen fertilizer use, 0–118 kg (0–260 lb) of nitrogen per acre. Macropore flow is listed in percent, average per study area based on determinations from dye studies. In this instance, macropore flow is used to also entail preferential flow paths. Nitrate concentrations ranged from 0.1 to 45 mgL −1 . Triazine-herbicide concentrations were detected in samples from five of the six study areas in concentrations ranging from 0.1 to 2.3 μL −1 . Analysis indicated that there were significant differences in nitrate concentrations (averages-at 95 % confidence level using Kendall Test) among the six study areas; no significant differences in triazineherbicide concentrations were found. Concentrations of nitrate and triazine herbicide were determined (using contingency-table analysis), to be significantly larger in more intensively irrigated areas compared to less intensively irrigated areas. Preliminary correlations with the independent variables and nitrate concentrations indicated significant relations at the 95%confidence level with variables hydraulic conductivity, well depth, and irrigation well density. Correlations with triazine-herbicide concentrations indicated significant relations with hydraulic conductivity, specific discharge, well depth, annual precipitation, and irrigation well density, as well as nitrate concentrations. Simple multiple-regression technique indicated that well depth and density and fertilizer use explained about 51 % of the variation in nitrate concentrations. Specific discharge and well depth explained about 60 % of the variation in triazine-herbicide concentrations. Macropore flow paths and specific discharge explained 84 % of the total variation in triazineherbicide concentrations. The use of trade names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.

Nebraska↗
USGS2010

Water security-National and global issues

Potable or clean freshwater availability is crucial to life and economic, environmental, and social systems. The amount of freshwater is finite and makes up approximately 2.5 percent of all water on the Earth. Freshwater supplies are small and randomly distributed, so water resources can become points of conflict. Freshwater availability depends upon precipitation patterns, changing climate, and whether the source of consumed water comes directly from desalination, precipitation, or surface and (or) groundwater. At local to national levels, difficulties in securing potable water sources increase with growing populations and economies. Available water improves living standards and drives urbanization, which increases average water consumption per capita. Commonly, disruptions in sustainable supplies and distribution of potable water and conflicts over water resources become major security issues for Government officials. Disruptions are often influenced by land use, human population, use patterns, technological advances, environmental impacts, management processes and decisions, transnational boundaries, and so forth.

Fact Sheet↗
USGS2009

Water security - Nation state and international security implications

A terrorist attack such as poisoning and sabotage of the national water supply and water-quality infrastructure of the continental United States or any country, could disrupt the delivery of vital human services, threaten both public health and the environment, potentially cause mass casualties and pose grave public concern for homeland security. Most significantly, an attack on water resources would weaken social cohesion and trust in government. A threat to continuity of services is a potential threat to continuity of government since both are necessary for continuity of operations. Water infrastructure is difficult to protect, as it extends over vast areas across the U.S. and for which ownership is overwhelmingly nonfederal (approximately 85 percent). Since the 9111 attacks, federal dam operators and water and wastewater utilities have established counter measures. Similar measures have been taken in countries around the world. These include enhanced physical security, improved coordination between corporate ownership, Department of Homeland Security, and local law enforcement, and research into risk assessment and vulnerability analysis to ensure greater system safety. A key issue is the proportionate additional resources directed at public and private sector specific priorities. Agencies that have the scientific and technological ability to leverage resources, exploit integrated science approaches, focus on interdisciplinary practices, utilize informatics expertise and employ a wide use of evolving technologies should play a key role in water security and related issues.

Disaster Advances↗
USGS2008

Reconnaissance study of water quality in the mining-affected Aries River Basin, Romania

The Aries River basin of western Romania has been subject to mining activities as far back as Roman times. Present mining activities are associated with the extraction and processing of various metals including Au, Cu, Pb, and Zn. To understand the effects of these mining activities on the environment, this study focused on three objectives: (1) establish a baseline set of physical parameters, and water- and sediment-associated concentrations of metals in river-valley floors and floodplains; (2) establish a baseline set of physical and chemical measurements of pore water and sediment in tailings; and (3) provide training in sediment and water sampling to personnel in the National Agency for Mineral Resources and the Rosia Poieni Mine. This report summarizes basin findings of physical parameters and chemistry (sediment and water), and ancillary data collected during the low-flow synoptic sampling of May 2006.

Aries River Basin↗
USGS1995

Nitrate transport and transformation processes in unsaturated porous media

A series of experiments was conducted on two contrasting agricultural soils to observe the influence of soil texture, preferential flow, and plants on nitrate transport and denitrification under unsaturated conditions. Calcium nitrate fertilizer was applied to the surface of four large undisturbed soil cores (30 cm diameter by 40 cm height). Two of the cores were a structured clay obtained from central Missouri and two were an unstructured fine sand obtained from central Florida. The cores were irrigated daily and maintained at a matric potential of -20 kPa, representative of soil tension in the rooting zone of irrigated agricultural fields. Volumetric water content (θ), concentration of nitrate-N in the soil solution, and nitrous oxide flux at the surface, 10, 20, and 30 cm were monitored daily. Leaching loss of surface-applied N0 3 − -N was significant in both the sand and the clay. In unplanted sand cores, almost all of the applied nitrate was leached below 30 cm within 10 days. Gaseous N loss owing to denitrification was no greater than 2% of the nitrate-N applied to the unplanted sand cores and, in general, was less than 1 %. Although leaching was somewhat retarded in the clay cores, about 60% of the applied nitrate-N was leached from the unplanted clay soil in 5–6 weeks. Under unsaturated conditions, the clay had little to no tendency to denitrify despite the greater moisture content of the clay and retarded leaching of nitrate in the clay. The planted sand cores had surprisingly large gaseous N loss owing to denitrification, as much as 17% of the nitrate-N. Results from both the clay and sand experiments show that the dynamics of nitrate transport and transformation in unsaturated soils are affected by small, localized variations in the soil moisture content profile, the gaseous diffusion coefficient of the soil, the rate at which the nitrate pulse passes through the soil, the solubility of N 2 O and N 2 and the diffusion of the gasses through the soil solution, and development of a water content profile in the soil. Limited dentrification in the clay soil was due to a limited volume of soil available for infiltration after internal catchment and the development of denitrifying conditions resulting from the presence of an extensive macropore system.

Journal of Hydrology↗
USGS1994

Effects of land disposal of municipal sewage sludge on fate of nitrates in soil, streambed sediment, and water quality

This study was undertaken to determine the effects of sewage-sludge disposal at the Lowry sewage-sludge-disposal area, near Denver, Colorado, on ground- and surface-water quality, to determine the fate of nitrates from sludge leachate, and to determine the source areas of leachate and the potential for additional leaching from the disposal area. Sewage-sludge disposal began in 1969. Two methods were used to apply the sludge: burial and plowing. Also, the sludge was applied both in liquid and cake forms. Data in this report represent the chemical composition of soil and streambed sediment from seven soil- and four streambed-sampling sites in 1986, chemical and bacterial composition of ground water from 28 wells from 1981 to 1987, and surface-water runoff from seven water-sampling sites from 1984 to 1987. Ground water samples were obtained from alluvial and bedrock aquifers. Samples of soil, streambed sediment, ground water and surface water were obtained for onsite measurement and chemical analysis. Measurements included determination of nitrogen compounds and major cations and anions, fecal-coliform and -streptococcus bacteria, specific conductance, and pH. Thirteen wells in the alluvial aquifer in Region 3 of the study area contain water that was probably affected by sewage-sludge leachate. The plots of concentration of nitrate with time show seasonal trends and trends caused by precipitation. In addition to yearly fluctuation, there were noticeable increases in ground-water concentrations of nitrate that coincided with increased precipitation. After 3 years of annual ground-water-quality monitoring and 4 years of a quarterly sampling program, it has been determined that leachate from the sewage-sludge-disposal area caused increased nitrite plus nitrate (as nitrogen) concentration in the alluvial ground water at the site. Soil analyses from the disposal area indicate that organic nitrogen was the dominant form of nitrogen in the soil. As a result of investigations at the research site, it has been determined that a potentially large source of contamination exists in the soils of the study area owing to increased concentrations of nitrogen, sodium, calcium, magnesium, sulfate, bicarbonate, and chloride because of sewage disposal. Continued monitoring of surface and ground water for nitrogen and the other ions previously mentioned is required to assess long-term effects of municipal sludge disposal on water quality.

Journal of Hydrology↗