Evaluation of physical parameterizations for atmospheric river induced precipitation and application to long-term reconstruction based on three reanalysis datasets in Western Oregon.

Dynamically downscaled precipitation is often used for evaluating sub-daily precipitation behavior on a watershed-scale and for the input to hydrological modeling because of its increasing accuracy and spatiotemporal resolution. Despite these advantages, physical parameterizations in regional models and systematic biases due to the dataset used for boundary conditions greatly influence the quality of downscaled precipitation data. The present paper aims to evaluate the performance and the sensitivities of physical parameterizations of the Weather Research and Forecasting (WRF) model to simulate extreme precipitation associated with atmospheric rivers (ARs) over the Willamette watershed in Oregon. Also investigated was whether the optimized WRF configuration for extreme events can be used for long-term reconstruction using different boundary condition datasets. Three reanalysis datasets, the Twentieth Century Reanalysis version 2c (20CRv2c), the European Center for Medium-Range Weather Forecasts (ECMWF) twentieth century reanalysis (ERA20C), and the Climate Forecast System Reanalysis (CFSR), which have different spatial resolutions and dataset periods, were used to simulate precipitation at 4 km resolution. Sensitivity analyses showed that AR precipitation is most sensitive to the microphysics parameterization. Among 13 microphysics schemes investigated, the Goddard and the Stony-Brook University schemes performed the best regardless of the choice of reanalysis. Reconstructed historical precipitation with the optimized configuration showed better accuracies during the wet season than the dry season. With respect to simulations with CFSR, it was found that the optimized configuration for AR precipitation can be used for long-term reconstruction with small biases. However, systematic biases in the reanalysis datasets may still lead to uncertainties in downscaling precipitation in a different season with a single configuration.

Exposure assessment framework for antimicrobial copper use in urbanized areas.

Copper is used as an antimicrobial agent in building materials such as algae-resistant roofing shingles and treated wood products for decks, fences, and utility poles used in urbanized areas. Releases from these materials may pose risks to aquatic and terrestrial organisms. Copper exposures in surface water, sediment, and soil were estimated for a hypothetical urban setting using the TREX watershed model. Drainage and soil characteristics were based on an existing watershed. Urban landscape characteristics were developed from data regarding housing densities and copper use in building materials. This setting provides a spatially distributed, upper-bound assessment scenario. Release rates from algae-resistant shingles and treated wood were defined based on surface area and rainfall. Simulations for the urban landscapes were performed for a 10-year period. Simulation results were used to evaluate exceedences of benchmark concentrations for water, sediment, and soil. For algae-resistant shingles, exposures did not exceed benchmarks in any media. For treated wood, exposures did not exceed sediment and soil benchmarks, and surface water benchmarks were exceeded on 2 days in 10 years. Based on this analysis, copper use as an antimicrobial agent in algae resistant shingles and treated wood is not expected to pose significant adverse environmental risks on an individual use basis.

Parenteral administration of recombinant human neuregulin-1 to patients with stable chronic heart failure produces favourable acute and chronic haemodynamic responses.

AIMS: Neuregulin-1 (NRG-1) plays a critical role in the adaptation of the heart to injury, inhibiting apoptosis and inducing cardiomyocyte proliferation. We have shown previously that rhNRG-1 improves cardiac function and survival in animal models of cardiomyopathy. Here we report the first human study aimed at exploring the acute and chronic haemodynamic responses to recombinant human NRG-1 (beta(2a) isoform; rhNRG-1) in patients with stable chronic heart failure (CHF). METHODS AND RESULTS: Fifteen patients (age, 60 ± 2; NYHA II:III, 9:6; left ventricular ejection fraction (LVEF) <40%) on optimal medical therapy for CHF, received a rhNRG-1 infusion daily for 11 days. Acute and chronic haemodynamic, structural and biochemical effects were determined by serial right heart catheterization, cardiac magnetic resonance (CMR), echocardiography and measurement of neurohumoral indices. Acutely, cardiac output increased by 30% during a 6 h rhNRG-1 infusion (P < 0.01). Pulmonary artery wedge pressure and systemic vascular resistance decreased 30 and 20%, respectively, at 2 h (P < 0.01). A 47% reduction in serum noradrenaline, a 55% reduction in serum aldosterone and a 3.6-fold increase in N-terminal prohormone brain natriuretic peptide levels were concurrently observed (P < 0.001). These acute haemodynamic effects were sustained, as demonstrated by the 12% increase in LVEF from 32.2 ± 2.0% (baseline) to 36.1 ± 2.3% (mean ± SE, P < 0.001) at 12 weeks. The therapy was well tolerated. CONCLUSION: rhNRG-1 appears to produce favourable acute and chronic haemodynamic effects in patients with stable CHF on optimal medical therapy. Randomized controlled trials of rhNRG-1 in cardiac disease are thus warranted. Clinical Trial Registration Information The trial was registered with the Australian New Zealand Clinical Trials Registry, anzctr.org.au Identifier: ACTRN12607000330448.

TREX: spatially distributed model to assess watershed contaminant transport and fate.

Contaminant releases from upland areas can have adverse water quality and stream ecology impacts. TREX (Two-dimensional, Runoff, Erosion, and Export) is a spatially distributed, physically-based model to simulate chemical transport and fate at the watershed scale. TREX combines surface hydrology and sediment transport features from the CASC2D watershed model with chemical transport features from the WASP/IPX series of water quality models. In addition to surface runoff and sediment transport, TREX simulates: (1) chemical erosion, advection, and deposition; (2) chemical partitioning and phase distribution; and (3) chemical infiltration and redistribution. Floodplain interactions for water, sediment, and chemicals are also simulated. To demonstrate the potential for using TREX to simulate chemical transport at the watershed scale, a screening-level application was developed for the California Gulch watershed mine-waste site in Colorado. Runoff, sediment transport, and metals (Cu, Cd, Zn) transport were simulated for a calibration event and a validation event. The model reproduced measured peak flows, and times to peak at the watershed outlet and three internal locations. Simulated flow volumes were within approximately 10% of measured conditions. Model results were also generally within measured ranges of total suspended solid and metal concentrations. TREX is an appropriate tool for investigating multimedia environmental problems that involve water, soils, and chemical interactions in a spatially distributed manner within a watershed.

Simulation of metals transport and toxicity at a mine-impacted watershed: California Gulch, Colorado.

The transport and toxicity of metals at the California Gulch, Colorado mine-impacted watershed were simulated with a spatially distributed watershed model. Using a database of observations for the period 1984-2004, hydrology, sediment transport, and metals transport were simulated for a June 2003 calibration event and a September 2003 validation event. Simulated flow volumes were within approximately 10% of observed conditions. Observed ranges of total suspended solids, cadmium, copper, and zinc concentrations were also successfully simulated. The model was then used to simulate the potential impacts of a 1-in-100-year rainfall event. Driven by large flows and corresponding soil and sediment erosion for the 1-in-100-year event, estimated solids and metals export from the watershed is 10,000 metric tons for solids, 215 kg for Cu, 520 kg for Cu, and 15,300 kg for Zn. As expressed by the cumulative criterion unit (CCU) index, metals concentrations far exceed toxic effects thresholds, suggesting a high probability of toxic effects downstream of the gulch. More detailed Zn source analyses suggest that much of the Zn exported from the gulch originates from slag piles adjacent to the lower gulch floodplain and an old mining site located near the head of the lower gulch.