Accurate Simulation of Flow through Dipping Aquifers with MODFLOW 6 Using Enhanced Cell Connectivity.

In simulations of groundwater flow through dipping aquifers, layers of model cells are often "deformed" to follow the top and bottom elevations of the aquifers. When this approach is used in MODFLOW, adjacent cells within the same model layer are vertically offset from one another, and the standard conductance-based (two-point) formulation for flow between cells does not rigorously account for these offsets. The XT3D multi-point flow formulation in MODFLOW 6 is designed to account for geometric irregularities in the grid, including vertical offsets, and to provide accurate results for both isotropic and anisotropic groundwater flow.

Severe, Symptomatic Hypercalcemia Secondary to PTH-secreting Pancreatoblastoma.

Hypercalcemia may be induced by a variety of etiologies, most commonly primary hyperparathyroidism. Although primary hyperparathyroidism represents a relatively common endocrinological disorder, ectopic PTH secretion is a rare entity that is less well described in literature. We describe the first case to our knowledge of severe, symptomatic hypercalcemia found to be secondary to a PTH-secreting pancreatoblastoma.

Structural Uncertainty Due to Fault Timing: A Multimodel Case Study from the Perth Basin.

Faults can fundamentally change a groundwater flow regime and represent a major source of uncertainty in groundwater studies. Much research has been devoted to uncertainty around their location and their barrier-conduit behavior. However, fault timing is one aspect of fault uncertainty that appears to be somewhat overlooked.

Quantifying Carbon Cycling across the Groundwater-Stream-Atmosphere Continuum Using High-Resolution Time Series of Multiple Dissolved Gases.

The quantification of carbon cycling across the groundwater-stream-atmosphere continuum (GSAC) is crucial for understanding regional and global carbon cycling. However, this quantification remains challenging due to highly coupled carbon exchange and turnover in the GSAC. Here, we disentangled carbon cycling processes in a representative groundwater-stream-atmosphere transect by obtaining and numerically simulating high-resolution time series of dissolved He, Ar, Kr, O, CO, and CH concentrations.

Corrigendum to: The measurement of ambient air moisture stable isotope composition for the accurate estimation of evaporative losses. MethodsX 11 (2023) 102265.

[This corrects the article DOI: 10.1016/j.mex.

The measurement of ambient air moisture stable isotope composition for the accurate estimation of evaporative losses.

Accurate estimation of evaporative losses from a water body, using the Craig-Gordon model and the stable hydrogen and oxygen isotope composition of water, requires knowledge of the stable isotope composition of ambient air moisture. This is rarely measured in the field, and it is usually estimated assuming that recent rainfall remains in isotopic equilibrium with atmospheric moisture. However, the ambient air moisture stable isotope composition may vary significantly at different heights above the water body.

Revisiting MODFLOW's Capability to Model Flow Through Sedimentary Structures.

Sedimentary structures have unique geometries and anisotropic hydraulic conductivity, both of which control groundwater flow. Traditional finite-difference simulators (e.g.

Fate of trace organic compounds in the hyporheic zone: Influence of microbial metabolism.

The hyporheic zone (HZ) is considered a hydrodynamically-driven bioreactor with significant pollutant removal capacities and can therefore not only improve wholestream water quality but also preserve human and ecosystem health. Microbial metabolism is hypothesized to play a key role in pollutant transformation in hyporheic sediments of natural streams. However, previous work investigating the influence of microbial metabolism on pollutant transformation has been predominantly laboratory studies.

Determining hyporheic removal rates of trace organic compounds using non-parametric conservative transport with multiple sorption models.

Assessing the transport and reactive processes of contaminants in freshwater streams is crucial in managing water resources sustainably. Particularly the hyporheic zone, the sediment-water interface where surface water and groundwater mix, may possess significant contaminant removal capacities due to its myriad physical, chemical, and microbiological processes. However, modelling approaches aiming at assessing the hyporheic zone's reactivity are either based on simple assumptions, such as, predefining the shape of the residence times distribution (RTD) function, or are computationally not feasible due to a too detailed system characterisation.

Including Vertical Fault Structures in Layered Groundwater Flow Models.

Accurate representation of groundwater flow and solute transport requires a sound representation of the underlying geometry of aquifers. Faults can have a significant influence on the structure and connectivity of aquifers, which may allow permeable units to connect, and aquifers to seal when juxtaposed against lower permeability units. Robust representation of groundwater flow around faults remains challenging despite the significance of faults for flow and transport.

Hyporheic Exchange Controls Fate of Trace Organic Compounds in an Urban Stream.

First-order half-lives for 26 trace organic compounds (TrOCs) were determined in the hyporheic zone (HZ) and along a 3 km reach of a first-order stream in South Australia during both dry and wet seasons. Two salt tracer experiments were conducted and evaluated using a transient storage model to characterize seasonal differences in stream residence time and transient storage. Lagrangian and time-integrated surface water sampling were conducted to calculate half-lives in the surface water.

Effects of Intraborehole Flow on Purging and Sampling Long-Screened or Open Wells.

Hydraulic head differences across the screened or open interval of a well significantly influence the sampled water mixture. Sample bias can occur due to an insufficient pumping rate and/or due to native groundwater displacement by intraborehole flow (IBF). Proper understanding of the sampled water mixture is crucial for accurate interpretation of environmental tracers and groundwater chemistry data, and hence groundwater characterization.

The evolution of an integrated ultrasound curriculum (iUSC) for medical students: 9-year experience.

Interest in ultrasound education in medical schools has increased dramatically in recent years as reflected in a marked increase in publications on the topic and growing attendance at international meetings on ultrasound education. In 2006, the University of South Carolina School of Medicine introduced an integrated ultrasound curriculum (iUSC) across all years of medical school. That curriculum has evolved significantly over the 9 years.

A 52-Year-Old Man With a Tuft Fracture and Hand Cellulitis.

A 52-year-old man presented to the emergency department (ED) 1 week after getting his right index finger shut in a car door. The patient complained of right index finger pain. His entire hand was edematous and reddened.

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China.

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33-521mg/L) in NO3(-) concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ(18)O, δ(2)H) analysis, (3)H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems.

Limitations of the use of environmental tracers to infer groundwater age.

Apparent ages obtained from the measured concentrations of environmental tracers have the potential to inform recharge rates, flow rates, and assist in the calibration of groundwater models. A number of studies have investigated sources of error in the relationships between the apparent ages, and the age assumed by models to relate this quantity to an aquifer property (e.g.

Bias of apparent tracer ages in heterogeneous environments.

The interpretation of apparent ages often assumes that a water sample is composed of a single age. In heterogeneous aquifers, apparent ages estimated with environmental tracer methods do not reflect mean water ages because of the mixing of waters from many flow paths with different ages. This is due to nonlinear variations in atmospheric concentrations of the tracer with time resulting in biases of mixed concentrations used to determine apparent ages.

An analysis of river bank slope and unsaturated flow effects on bank storage.

Recognizing the underlying mechanisms of bank storage and return flow is important for understanding streamflow hydrographs. Analytical models have been widely used to estimate the impacts of bank storage, but are often based on assumptions of conditions that are rarely found in the field, such as vertical river banks and saturated flow. Numerical simulations of bank storage and return flow in river-aquifer cross sections with vertical and sloping banks were undertaken using a fully-coupled, surface-subsurface flow model.

The primary care osteoporosis risk of fracture screening (POROS) study: design and baseline characteristics.

Objective: POROS evaluates a 3-step fracture risk screening program in women 50-64 not previously diagnosed with osteoporosis. This report details the research design and baseline characteristics.

Methods: Recruiting from 6 primary care sites, baseline characteristics, including fracture risk factors, were assessed via self-administered questionnaires (SAQs).