New Capabilities in MT3D-USGS for Simulating Unsaturated-Zone Heat Transport.

Changes in climate and land use will alter groundwater heat transport dynamics in the future. These changes will in turn affect watershed processes (e.g., nutrient cycling) as well as watershed characteristics (e.g., distribution and persistence of cold-water habitat). Thus, groundwater flow and heat transport models at watershed scales that can characterize and quantify thermal impacts of surface temperature change on groundwater system temperatures may support forecasting changes to groundwater-linked ecosystems in riparian zones, streams, and lakes. Including unsaturated zone processes has previously been shown to be important for properly determining the timing and magnitude of groundwater recharge (Hunt et al. 2008). Similarly, heat transport dynamics in the saturated-zone, as well as connected surface-water systems, can be appreciably influenced by unsaturated-zone processes; in this way the unsaturated zone forms an inextricable link between the land surface where change occurs and the groundwater system that transmits that change. This paper presents new capabilities for the existing MT3D-USGS transport simulator by adding functionality for simulating heat transport through the unsaturated zone. New simulation capabilities are verified through comparison of simulation results with those of the variably saturated heat transport simulator VS2DH under steady and transient conditions for both water and heat flow. The new capabilities are assessed using a number of conceptualizations and include evaluations of convective and conductive heat flow. These additional capabilities increase the utility for applied watershed-scale simulations, which in turn may facilitate more realistic characterizations of temperature change on thermally sensitive ecosystems, such as stream habitat.

'As for dignity and respect . me bollix': A human rights-based exploration of service user narratives in Irish methadone maintenance treatment.

INTRODUCTION: This paper explores the narratives of service users of contemporary methadone maintenance treatment services (MMT) in the Republic of Ireland to obtain their perspectives in the context of them negotiating their right to health METHODS: Participants were recruited and interviewed by a former service user of MMT services. In-depth qualitative interviews were conducted with 40 current and recent users of MMT services RESULTS: Participants overwhelmingly reported a reduced sense of personal agency because of their experiences in MMT treatment. Participants observed that their perceptions of treatment were forged by a sense of reduced autonomy, coercive and disrespectful approaches from healthcare workers. Within a system which the participants considered to be failing, the services that they accessed were predicated on a process of reward and punishment, where best practice was often ignored by practitioners, all of which resulted in adverse consequences for service users DISCUSSION: The findings indicate that there is a significant 'chasm' between human rights, policy and best practice and how these are operationalised within the structures and practices of Irish MMT services. The treatment of service users, based on human rights principles such as equality, respect, autonomy, empowerment and personal choice remains aspirational and is unlikely to be fulfilled without addressing more systemic challenges such as funding, training of staff, service culture, governance and independent oversight of MMT services.

VS2DRTI: Simulating Heat and Reactive Solute Transport in Variably Saturated Porous Media.

Variably saturated groundwater flow, heat transport, and solute transport are important processes in environmental phenomena, such as the natural evolution of water chemistry of aquifers and streams, the storage of radioactive waste in a geologic repository, the contamination of water resources from acid-rock drainage, and the geologic sequestration of carbon dioxide. Up to now, our ability to simulate these processes simultaneously with fully coupled reactive transport models has been limited to complex and often difficult-to-use models. To address the need for a simple and easy-to-use model, the VS2DRTI software package has been developed for simulating water flow, heat transport, and reactive solute transport through variably saturated porous media. The underlying numerical model, VS2DRT, was created by coupling the flow and transport capabilities of the VS2DT and VS2DH models with the equilibrium and kinetic reaction capabilities of PhreeqcRM. Flow capabilities include two-dimensional, constant-density, variably saturated flow; transport capabilities include both heat and multicomponent solute transport; and the reaction capabilities are a complete implementation of geochemical reactions of PHREEQC. The graphical user interface includes a preprocessor for building simulations and a postprocessor for visual display of simulation results. To demonstrate the simulation of multiple processes, the model is applied to a hypothetical example of injection of heated waste water to an aquifer with temperature-dependent cation exchange. VS2DRTI is freely available public domain software.

1DTempPro V2: New Features for Inferring Groundwater/Surface-Water Exchange.

A new version of the computer program 1DTempPro extends the original code to include new capabilities for (1) automated parameter estimation, (2) layer heterogeneity, and (3) time-varying specific discharge. The code serves as an interface to the U.S. Geological Survey model VS2DH and supports analysis of vertical one-dimensional temperature profiles under saturated flow conditions to assess groundwater/surface-water exchange and estimate hydraulic conductivity for cases where hydraulic head is known.

1DTempPro: analyzing temperature profiles for groundwater/surface-water exchange.

A new computer program, 1DTempPro, is presented for the analysis of vertical one-dimensional (1D) temperature profiles under saturated flow conditions. 1DTempPro is a graphical user interface to the U.S. Geological Survey code Variably Saturated 2-Dimensional Heat Transport (VS2DH), which numerically solves the flow and heat-transport equations. Pre- and postprocessor features allow the user to calibrate VS2DH models to estimate vertical groundwater/surface-water exchange and also hydraulic conductivity for cases where hydraulic head is known.

Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS.

The MT3DMS groundwater solute transport model was modified to simulate solute transport in the unsaturated zone by incorporating the unsaturated-zone flow (UZF1) package developed for MODFLOW. The modified MT3DMS code uses a volume-averaged approach in which Lagrangian-based UZF1 fluid fluxes and storage changes are mapped onto a fixed grid. Referred to as UZF-MT3DMS, the linked model was tested against published benchmarks solved analytically as well as against other published codes, most frequently the U.S. Geological Survey's Variably-Saturated Two-Dimensional Flow and Transport Model. Results from a suite of test cases demonstrate that the modified code accurately simulates solute advection, dispersion, and reaction in the unsaturated zone. Two- and three-dimensional simulations also were investigated to ensure unsaturated-saturated zone interaction was simulated correctly. Because the UZF1 solution is analytical, large-scale flow and transport investigations can be performed free from the computational and data burdens required by numerical solutions to Richards' equation. Results demonstrate that significant simulation runtime savings can be achieved with UZF-MT3DMS, an important development when hundreds or thousands of model runs are required during parameter estimation and uncertainty analysis. Three-dimensional variably saturated flow and transport simulations revealed UZF-MT3DMS to have runtimes that are less than one tenth of the time required by models that rely on Richards' equation. Given its accuracy and efficiency, and the wide-spread use of both MODFLOW and MT3DMS, the added capability of unsaturated-zone transport in this familiar modeling framework stands to benefit a broad user-ship.

Effectiveness of two opioid antagonists in treating opioid-induced constipation.

AIM: This literature review reports the effectiveness of two peripheral opioid antagonists to relieve constipation caused by prolonged use of opioids, primarily in patients with advanced cancer. BACKGROUND: Opioid-induced constipation can cause great discomfort to patients who use opioids for prolonged periods and on occasion decline pain-relief in an effort to help aid laxation. The use of peripheral opioid antagonists can help reverse the slowing of the gut caused by the opioids, but the correct one must be used in order not to reverse the important analgesic effects the opioids provide. DATA SOURCES: Information was obtained by searching the databases British Nursing Index, CINAHL and Medline. REVIEW METHODS: Selection criteria were as follows: original research in the form of randomized controlled trials; articles had to be written in English; articles had to focus on the effectiveness of naloxone and methylnaltrexone in the treatment of opioid-induced constipation; the search was limited to the period 1990-2008. RESULTS: Nineteen articles were included in the study. The results from the studies indicate that due to fewer withdrawal effects and less reversal of analgesia experienced, methylnaltrexone is more effective at relieving opioid-induced constipation. CONCLUSION: The recent development of methylnaltrexone into a commercially-viable drug indicates its effectiveness. It may help patients suffering from the intense discomfort that constipation can cause.

Water movement within the unsaturated zone in four agricultural areas of the United States.

Millions of tons of agricultural fertilizer and pesticides are applied annually in the USA. Due to the potential for these chemicals to migrate to groundwater, a study was conducted in 2004 using field data to calculate water budgets, rates of groundwater recharge and times of water travel through the unsaturated zone and to identify factors that influence these phenomena. Precipitation was the only water input at sites in Indiana and Maryland; irrigation accounted for about 80% of total water input at sites in California and Washington. Recharge at the Indiana site (47.5 cm) and at the Maryland site (31.5 cm) were equivalent to 51 and 32%, respectively, of annual precipitation and occurred between growing seasons. Recharge at the California site (42.3 cm) and Washington site (11.9 cm) occurred in response to irrigation events and was about 29 and 13% of total water input, respectively. Average residence time of water in the unsaturated zone, calculated using a piston-flow approach, ranged from less than 1 yr at the Indiana site to more than 8 yr at the Washington site. Results of bromide tracer tests indicate that at three of the four sites, a fraction of the water applied at land surface may have traveled to the water table in less than 1 yr. The timing and intensity of precipitation and irrigation were the dominant factors controlling recharge, suggesting that the time of the year at which chemicals are applied may be important for chemical transport through the unsaturated zone.

Variations in pesticide leaching related to land use, pesticide properties, and unsaturated zone thickness.

Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a maximum of 18.7 m. Average annual recharge to ground water decreased from 15.9 to 11.1 cm as the unsaturated zone increased in thickness from 1 to 10 m. These point estimates of recharge are at the lower end of previously published values, which used methods that integrate over larger areas capturing focused recharge in the numerous detention ponds in the watershed. The total amount of applied and leached masses for five parent pesticide compounds and seven metabolites were estimated for the 32-km2 Morgan Creek watershed by associating each hectare to the closest one-dimensional model analog of model depth and crop rotation scenario as determined from land-use surveys. LEACHM parameters were set such that branched, serial, first-order decay of pesticides and metabolites was realistically simulated. Leaching is predicted to be greatest for shallow soils and for persistent compounds with low sorptivity. Based on simulation results, percent parent compounds leached within the watershed can be described by a regression model of the form e(-depth) (a ln t1/2-b ln K OC) where t1/2 is the degradation half-life in aerobic soils, K OC is the organic carbon normalized sorption coefficient, and a and b are fitted coefficients (R2 = 0.86, p value = 7 x 10(-9)).

Flow and storage in groundwater systems.

The dynamic nature of groundwater is not readily apparent, except where discharge is focused at springs or where recharge enters sinkholes. Yet groundwater flow and storage are continually changing in response to human and climatic stresses. Wise development of groundwater resources requires a more complete understanding of these changes in flow and storage and of their effects on the terrestrial environment and on numerous surface-water features and their biota.