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In this chapter, the laboratory and field techniques for studying microbial transport behaviour in aquifer materials and model porous media are described and discussed.
Atrazine, a herbicide widely used for corn production in the Midwest, has been detected in groundwater of several states, and has been identified as a possible human carcinogen. With the widespread use of pesticides in crop production, and the frequent detection of these chemicals in groundwater, large-scale risk assessments would help water resource managers to identify areas that are more susceptible to contamination and implement practices to ameliorate the problem. This paper presents an integrated, visual and interactive system for predicting potential environmental risks associated with pesticide contamination at spatial scales ranging from fields to landscapes and regions. The interactive system extends the...
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The ascii grids represent regional probabilities that groundwater in a particular location will have dissolved oxygen (DO) concentrations less than selected threshold values representing anoxic groundwater conditions or will have dissolved manganese (Mn) concentrations greater than selected threshold values representing secondary drinking water-quality contaminant levels (SMCL) and health-based screening levels (HBSL) for water quality. The probability models were constrained by the alluvial boundary of the Central Valley to a depth of approximately 300 meters (m). We utilized prediction modeling methods, specifically boosted regression trees (BRT) with a Bernoulli error distribution within a statistical learning...
Spring‐fed wetlands are ecologically important habitats in arid and semi‐arid regions. Springs have been suggested as possible hydrologic refugia from droughts and climate change; however, springs that depend on recent precipitation or snowmelt for recharge may be vulnerable to warming and drought intensification. Springs that are expected to maintain their ecohydrologic function in a warmer, drier climate may be priorities for conservation and restoration. Identifying such springs is difficult because many springs lack hydrologic records of adequate temporal extent and resolution to assess their resilience to water cycle changes. This study demonstrates proof‐of‐concept for the assessment of certain spring types...
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This report is volume 2 of a two-volume ecological assessment of grassland ecosystems in the Southwestern United States. Broad-scale assessments are syntheses of current scientific knowledge, including a description of uncertainties and assumptions, to provide a characterization and comprehensive description of ecological, social, and economic components within an assessment area. Volume 1 of this assessment focused on the ecology, types, conditions, and management practices of Southwestern grasslands. Volume 2 (this volume) describes wildlife and fish species, their habitat requirements, and species-specific management concerns, in Southwestern grasslands. This assessment is regional in scale and pertains primarily...
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Most groundwater conservation and management efforts focus on protecting groundwater for drinking water and for other human uses with little understanding or focus on the ecosystems that depend on groundwater. However, groundwater plays an integral role in sustaining certain types of aquatic, terrestrial and coastal ecosystems, and their associated landscapes. Our aim was to illuminate the connection between groundwater and surface ecosystems by identifying and mapping the distribution of groundwater dependent ecosystems (GDEs) in California. This layer includes watersheds from the Watershed Boundary Database at the 12-digit hydrologic unit code (HUC12) scale. Each watershed is attributed with summary information...
Experiments were conducted to evaluate the impact of groundwater chemistry and travel distance on the transport and fate behavior of PRD-1, a bacteriophage employed as a surrogate tracer for pathogenic enteric viruses. The experiments were conducted in the unconfined aquifer at the United States Geological Survey Cape Cod Toxic-Substances Hydrology Research Site in Falmouth, Massachusetts. The transport behavior of bromide (Br−) and PRD-1 were evaluated in a sewage-effluent contaminated zone and a shallower uncontaminated zone at this site. Several multilevel sampling devices located along a 13-m transect were used to collect vertically discrete samples to examine longitudinal and vertical variability of PRD-1 retardation...
Categories: Publication; Types: Citation; Tags: Groundwater, Transport, Virus
Populations of chemotactic bacteria are able to sense and respond to chemical gradients in their surroundings and direct their migration toward increasing concentrations of chemicals that they perceive to be beneficial to their survival. It has been suggested that this phenomenon may facilitate bioremediation processes by bringing bacteria into closer proximity to the chemical contaminants that they degrade. To determine the significance of chemotaxis in these processes it is necessary to quantify the magnitude of the response and compare it to other groundwater processes that affect the fate and transport of bacteria. We present a systematic approach toward quantifying the chemotactic response of bacteria in laboratory...
The effects of a dilute (ionic strength = 5 × 10−3 M) plume of treated sewage, with elevated levels (3.9 mg/L) of dissolved organic carbon (DOC), upon the pH-dependency and magnitude of bacterial transport through an iron-laden, quartz sand aquifer (Cape Cod, MA) were evaluated using sets of replicate, static minicolumns. Compared with uncontaminated groundwater, the plume chemistry diminished bacterial attachment under mildly acidic (pH 5.0–6.5) in-situ conditions, in spite of the 5-fold increase in ionic strength and substantively enhanced attachment under more alkaline conditions. The effects of the hydrophobic neutral and total fractions of the plume DOC; modest concentrations of fulvic and humic acids (1.5...
A flexible, robust method for linking parent (regional-scale) and child (local-scale) grids of locally refined models that use different numerical methods is developed based on a new, iterative ghost-node method. Tests are presented for two-dimensional and three-dimensional pumped systems that are homogeneous or that have simple heterogeneity. The parent and child grids are simulated using the block-centered finite-difference MODFLOW and control-volume finite-element FEHM models, respectively. The models are solved iteratively through head-dependent (child model) and specified-flow (parent model) boundary conditions. Boundary conditions for models with nonmatching grids or zones of different hydraulic conductivity...
18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin...
The effects of a dilute (ionic strength = 5 × 10−3 M) plume of treated sewage, with elevated levels (3.9 mg/L) of dissolved organic carbon (DOC), upon the pH-dependency and magnitude of bacterial transport through an iron-laden, quartz sand aquifer (Cape Cod, MA) were evaluated using sets of replicate, static minicolumns. Compared with uncontaminated groundwater, the plume chemistry diminished bacterial attachment under mildly acidic (pH 5.0–6.5) in-situ conditions, in spite of the 5-fold increase in ionic strength and substantively enhanced attachment under more alkaline conditions. The effects of the hydrophobic neutral and total fractions of the plume DOC; modest concentrations of fulvic and humic acids (1.5...
Encyclopedia of Water Science provides instant access to the most effective procedures in agricultural water engineering, unveiling a wide spectrum of design concepts, methodologies, and solutions for enhanced performance of water quality, treatment, conservation, and irrigation methods, as well as improved water efficiency in agricultural programs. Online version features quarterly updates, keyword searchability, color graphics, and customized content views.
Streams and their surrounding catchments exchange water and solutes on a range of physical scales. Exchange with the stream may extend into the interstitial areas of the streambed, the hyporheic zone, the riparian area, or the catchment's groundwater flow system. Even at the smaller scales, the exchanges significantly influence solute transport, nutrient cycling, and the aquatic ecosystem. Over the recent decades, considerable attention has been given to the solute transport aspects of stream–groundwater interactions. Stream–groundwater interactions are now being recognized as practical matters to be considered in environmental issues, such as stream restoration and fish habitat. In this chapter, the emphasis is...
A rapid headspace method for the simultaneous laboratory determination of intentionally introduced hydrologic tracers, sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), Halon 1211 (CF2ClBr), and other halocarbons in water and gases is described. The high sensitivity of the procedure allows for introduction of minimal tracer mass (a few grams) into hydrologic systems with a large dynamic range of analytical detection (dilutions to 1:108). Analysis times by gas chromatography with electron capture detector are less than 1 min for SF6; about 2 min for SF6 and SF5CF3; and 4 min for SF6, SF5CF3, and Halon 1211. Many samples can be rapidly collected, preserved in stoppered septum bottles, and analyzed...
Categories: Publication; Types: Citation; Tags: SF5CF3, SF6, groundwater, halon, tracers
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In 2021 and 2022, the U.S. Geological Survey (USGS), in cooperation with the Idaho Department of Water Resources (IDWR), drilled and constructed well SEP 16 (431900112593601) approximately 6 miles south-southeast of Big Southern Butte in Butte County, Idaho. The purpose of the well installation was to collect geologic, geophysical, and hydrologic data. On July 13, 2022, the USGS Idaho National Laboratory Project Office (INLPO) collected select geophysical logs within the cased well including natural gamma, neutron, neutron porosity, and gamma-gamma dual density logs. Gyroscopic deviation data were also collected during geophysical surveying to account for the horizontal and vertical displacement of the well. On...
A two-dimensional finite element model was used to simulate the groundwater recovery process under various surface mining situations. The simulation results were used to predict the rate at which soil settlement takes place. It was found that the groundwater recovery process is very fast immediately after mine closure and cessation of dewatering programmes; a significant part of mine land settlement can be measured at such times. This paper presents a method for deriving the relationship between the re-establishment of the natural groundwater regime to its equilibrium position as existed prior to the commencement of mining operations and mine spoil settlement.
Evaluations of non-nitrogen nutrient budgets in pasture systems are limited, and there needs to be greater knowledge of these budgets. Although most nutrient budget studies from grasslands have focused solely or primarily on N, maintenance of a proper nutrient balance is important to healthy plant growth and reduction of potential water quality problems. Budgets of non-nitrogen nutrients were studied in a rotational pasture system during two treatment periods, which received different levels of nitrogen (N) fertility. Rotationally grazed grass pastures in Ohio (USA) received 56 kg N ha−1 as NH4NO3 for a 5-year period and then 168 kg N ha−1 for a 10-year period. A topsoil pH of 6.0 and available P and K levels of...
Groundwater dependent ecosystems (GDEs) rely on near-surface groundwater. These systems are receiving more attention with rising air temperature, prolonged drought, and where groundwater pumping captures natural groundwater discharge for anthropogenic use. Phreatophyte shrublands, meadows, and riparian areas are GDEs that provide critical habitat for many sensitive species, especially in arid and semi-arid environments. While GDEs are vital for ecosystem services and function, their long-term (i.e. ~ 30 years) spatial and temporal variability is poorly understood with respect to local and regional scale climate, groundwater, and rangeland management. In this work, we compute time series of NDVI derived from sensors...
The Biscayne aquifer is a highly transmissive karst limestone that serves as the sole source of drinking water to over two million residents in south Florida. The aquifer is characterized by eogenetic karst, where the most transmissive void space can be an interconnected, touching-vug, biogenically influenced porosity of biogenic origin. Public supply wells in the aquifer are in close proximity to lakes established by surface mining. The mining of the limestone has occurred to the same depths as the production wells, which has raised concerns about pathogen and chemical transport from these surface water bodies. Hydraulic and forced gradient tracer tests were conducted to augment geologic and geophysical studies...
map background search result map search result map Assessment of Grassland Ecosystem Conditions in the Southwestern United States: Wildlife and Fish, Volume 2 Mapping Groundwater Dependent Ecosystems in California Probability distribution grids of dissolved oxygen and dissolved manganese concentrations at selected thresholds in drinking water depth zones, Central Valley, California Drilling, construction, geophysical, water quality, and aquifer test data for well SEP 16, Butte County, Idaho Probability distribution grids of dissolved oxygen and dissolved manganese concentrations at selected thresholds in drinking water depth zones, Central Valley, California Mapping Groundwater Dependent Ecosystems in California Assessment of Grassland Ecosystem Conditions in the Southwestern United States: Wildlife and Fish, Volume 2