Total Discharge Research Articles

Calibrating a hydrological model in ungauged small river basins of the northeastern Tibetan Plateau based on near-infrared images

River discharge monitoring sites are scarce in high mountain basins, especially on the Tibetan Plateau where rivers are widely distributed. The potential for estimating river discharge using remote sensing has been widely utilized for large continental rivers, while its application to smaller regional rivers has been limited. To address this issue, we investigate the reliability of calibrating a hydrological model for two small subbasins lacking discharge data in the upstream region of the Heihe River located on the Tibetan Plateau, based solely on multiple pixel ratio (MPR) data derived from near-infrared satellite images. Using six independent calibration schemes based on discharge or MPR data, the value of MPR data for hydrological modeling is explored. We first calibrate a model using observed discharge data and Nash-Sutcliffe efficiencies (NSEs) based on non-dominated sorting genetic algorithm II (Q-NSE scheme). We then use estimated discharge values derived from MPR data and identify different parameter sets that result in the highest NSEs in a Monte Carlo-based uncertainty framework (Q-NSE-1, Q-NSE-2 and Q-NSE-3 schemes). Spearman rank coefficients between MPR data and observed discharge data are then used as an alternative way to calibrate the model (MPR-SR scheme). The MPR-SR scheme is also applied with a simple water-balance filter, which removes parameter sets, which result in either underestimated or overestimated total discharge volumes (MPR-SRF scheme). The Babao River Basin and Yeniugou River Basin are used to compare the different calibration schemes and to perform parameter sensitivity analyses. The MPR-SRF calibration scheme achieved better performance in both river basins, with NSEs of 0.63 and 0.62, respectively, during the validation period. This study demonstrates the potential of the MPR-SRF calibration scheme to enhance models of small ungauged river basins lacking ground discharge observation data, and provides insights into how remote sensing data can be more effectively combined with hydrological modelling.

Large-scale spatiotemporal variations, sources, and risk assessment of banned OCPs and PAHs in suspended particulate matter from the Negro river, Argentina

Organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) threaten the environment due to their wide environmental resistance. Environmental paradigms coexist along the Negro River (NR) in Argentina, South America, which flows to the sea below the latitude of 40o S; however, this is the first environmental assessment of OCPs and PAHs in water of the NR for more than 15 years. With 21 sampling sites covering a range of 600 km of river extension, we assessed 16 OCPs and 16 PAHs in suspended particulate material (SPM) with regard to their levels, seasonality, sources, and potential biological risk assessment. Using gas chromatography–mass spectrometry and gas chromatography coupled with electron capture detection, we found an overall mean value for Σ16 OCPs of 648.56 ng. g−1, d.w. Despite a ban spanning 25 years, an increasing trend of accumulation of hexachlorocyclohexanes (HCHs) and endosulfan was shown in the lower valley. The ɑ-HCH/ɤ-HCH and β-HCH/(ɑ + ɤ)-HCH ratios indicated a prevalent usage of technical HCH over lindane and recent HCH inputs. The most abundant compound, α-endosulfan, averaged 141.64 ng. g−1, d.w. and DDX (Σ 4,4′-DDE, 4,4′-DDD, and 4,4′-DDT) averaged 99.98 ng. g−1, d.w. Winter OCP loads in the NR reflected the runoff of the heaviest pesticide application period. We estimated the total discharge of DDT into the Atlantic ocean was 96 g.day−1, added to 458 g of HCHs and 257 g of endosulfans (ɑ + β + epoxide) adsorbed by the SPM. PAHs occurred widely along the river (38.83 ± 43.52 μg. g−1) and the highest levels coincided with locations with marked anthropogenic-related activity, such as petroleum/gas exploitation facilities. Risk quotient analysis showed a low risk posed by OCPs, but a high risk of potential effects on biota posed by the PAHs, highlighting the need for mitigation measures.

The origin of hydrological responses following earthquakes in a confined aquifer: insight from water level, flow rate, and temperature observations

Abstract. Although many mechanisms of earthquake-induced hydrological response have been proposed in recent decades, the origins of these responses remain enigmatic, and a quantitative understanding of them is lacking. In this study, we quantitatively analyze the mechanism of coseismic response in water level and flow rate from an artesian well in southwestern China before and after multiple earthquakes and reveal the origin of the earthquake-induced hydrological response based on the monitoring data of water temperature. Water level and temperature always show coseismic step-like increases following earthquakes, which are independent of the earthquakes' epicentral distances and magnitudes. Tidal analysis finds changes in aquifer and aquitard permeability following these earthquakes, which corresponds to the post-seismic total discharge of 85–273 m3 in 20 d after earthquakes. Furthermore, we couple the flow rate and temperature data to model the mixing processes that occurred following each earthquake. The results indicate that coseismic temperature changes are the result of the mixing of different volumes of water from shallow and deep aquifers, with the mixing ratio varying according to each earthquake.

A Multi-Objective Decision Model for Water Pollution Load Allocation under Uncertainty

In order to control the discharge of regional total pollutants in the region and improve the ability of water environment management and decision making, a multi-objective decision-making optimization model of water pollution load allocation was constructed, which took into account economy and fairness. The model takes the maximum environmental benefit and the minimum weighted comprehensive Gini coefficient as the objective function and takes into account the uncertainty and multi-objectives of the model, which is conducive to promoting economic development and ensuring the fairness of regional water pollutant discharge. A method based on Monte Carlo simulation coupled with a genetic algorithm was designed to obtain the optimal solution set through multiple simulation optimization. This model is applied to Anhui Province to solve the allocation optimization problem of total pollutant reduction in the 13th Five-Year Energy Conservation and Emission Reduction Plan. After the optimization of water pollution load distribution, the comprehensive Gini coefficients of COD and NH3-N are reduced by different ranges. The comprehensive Gini coefficient after COD optimization decreased by 2.4–4.6%, and the comprehensive Gini coefficient after NH3-N optimization decreased by 25.1–32.5%, which verified the feasibility and rationality of the model in the optimal allocation of the total discharge of regional water pollutants. The model takes into account uncertain subjective and objective factors that have an important impact on water pollutant discharge targets and decision variables, thus optimizing the total emissions of the entire regional control unit in both space and time.

Plasma energy efficiency and equivalent electrical circuit of the multi-tips pulsed corona discharge in dry air at atmospheric pressure

An electrical model equivalent multi-tips corona discharge was presented. The electrical parameters were estimated by the identification method based on the recursive least squares (RLS) algorithm.The estimated electrical parameters allow to determine the total discharge power and the power delivered by all the tips to ignite and maintain the plasma discharge and thus the energy efficiency during the discharge. This study allows to follow and control the discharge at each instant of its evolution. Thus, the operating conditions of the discharge can be optimized to increase the energy efficiency of the discharge.

Four-dimensional electrical resistivity imaging for monitoring pumping-induced saltwater intrusion in a coastal aquifer

Conventional views of saltwater intrusion (SWI), where a basal saline wedge extends inland below fresh groundwater, can be complicated by the influence of saltwater cells in the upper part of aquifers in areas affected by tidal cycles. Distinguishing the contribution of each saltwater source may prove fundamental for well design and resource management. Application of time-lapse electrical resistivity imaging (ERI) during a 32-h pumping test in a pristine unconfined coastal sand aquifer, affected by strong tidal ranges (>2 m), aimed to evaluate the potential of the method to characterize the source of induced SWI in four dimensions (three dimensions and time). Water level monitoring during the test revealed that at the end of pumping, the upper 2 m of the aquifer had dewatered in the vicinity of the well field, reversing hydraulic gradients between the aquifer and the sea. This induced SI, with mixing models of well head water quality suggesting that saline water contributions to total discharge rose from 4 % to 8 %. ERI results reflected dewatering through an increase in resistivity in the upper 2-6 m of the aquifer, while a decline in resistivity, relative to background conditions, occurred immediately below this, reflecting the migration of saline water through the upper layers of the aquifer to the pumping well. By contrast no change in resistivity occurred at depth, indicating no significant change in contribution from the basal saline water to discharge. Test findings suggest that future water resource development at the site should focus on close monitoring of shallow pumping, or pumping from deeper parts of the aquifer, while more generally demonstrating the value of time-lapse geophysical methods in informing coastal water resource management.

Experimental assessment of velocity and bed shear stress in the main channel of a meandering compound channel with one-sided blocks in floodplain

Meandering rivers have an important role in transporting runoff from rainfall, especially during floods. With many cities and villages along rivers and the construction of water-management structures in floodplains, the flow pattern of the meandering rivers changes in time of floods. Here the flow behaviors in meandering compound channels with smooth floodplains and one-sided building floodplains are investigated using laboratory experiments. The experiments have been performed at three relative depths of 0.29, 0.39 and 0.49 and the corresponding discharges. The results show that the block density in a floodplain has a significant effect on flow behavior in the main channel. So that, with the increase of the relative depth, the ratios of main channel discharge compared to the total discharge (Qmc/Q) decreases in the bends with minimal extension of blocks floodplain, the crossover areas and the bends with maximal extension of blocks floodplain. For a given Dr, the significant increase in the Manning's n values as the density of the blocks increases (approximately 30%). With increasing the blocks density from zero to 23.7%, the maximum Darcy–Weisbach friction factor in sections CS1 and CS7 increases by 110% and 2%, respectively, which shows that increasing the density of blocks does not have a great effect on f in the section CS7. Under one-sided blocked floodplain conditions, the maximum longitudinal velocity in the main channel in the section with maximal extension of the blocks in the floodplain (CS7) is greater than the section with minimal extension of blocks in the floodplain (CS1). At the relative depth of 0.49, the maximum value of depth-averaged velocity in sections CS1-4 decreased by an average of 52% compared to the smooth floodplain. The maximum shear stress on the bed at the apex section for all channels occurs near the convex side and the bed shear stress at all sections decreases with decreasing relative depth and in the section with minimal extension of blocks floodplain (CS1) and cross-over sections. The maximum shear stress of the bed decreases with increasing the block density and these changes are more near the convex side than the concave side.

On the different regimes of positive DC corona discharges as a function of electrical and geometrical parameters

This experimental study aims to better understand the electrical and optical properties of a positive DC corona discharge and to highlight the influence of applied voltage and electrode gap on the discharge regime. When the high voltage is increased, three successive regimes have been observed, including one that has never been reported in the literature to the best of our knowledge. This is certainly due to the fact that the tungsten needle used in these experiments is a commercial needle, with a tip of perfect surface finish. In fact, after the ignition voltage, the mean current slowly increases, and it perfectly follows the theoretical Townsend's law; this is the glow regime. When the voltage reaches a first threshold, a few small current pulses appear. However, this is not the breakdown streamer regime because photographs and intensified camera visualizations highlight that the propagation of streamers toward the grounded plate is limited to half of the gap. In this regime, the time-averaged current becomes higher than that of Townsend's law. Each current pulse is composed of only one bump, and the pulse frequency is higher (approximately 20 kHz) than that of the breakdown streamers. When the voltage reaches a second threshold, the magnitude of current pulses suddenly increases, but their frequency decreases (a few kHz); this is the transition toward the breakdown streamer regime. In this regime, each current pulse is composed of two bumps: the first one corresponds to the arrival of a primary streamer at the plate and the second one corresponds to a secondary streamer. Finally, we investigated the effects of the electrode gap. The magnitude and frequency of the current pulses increase when the gap decreases. Consequently, the offset between Townsend's curve and the experimental I–V characteristics increases when the gap decreases, because the pulse component of the total discharge current increases.

Interaction Between Surface and Underground Waters of the Itapemirim and Itabapoana River Basins in the Southern part of the State of Espírito Santo, Southeastern Brazil

Itapemirim River basin and part of the Itabapoana River basin are located in the southern area of the State of Espírito Santo, covering 26 municipalities. Knowledge of these basins’ hydrogeological characteristics provides information on the groundwater potential and the behavior of the river base flow during dry seasons. The objective of this study is to assess the relationship between surface and underground waters from the analysis of hydrograph units and information from tubular well logs. The Itabapoana River basin had the highest flow rates with mean specific capacity of 1415.1 m3 /h/m, while Itapemirim River basin wells yielded 0.6941 m3 /h/m. The percentage of underground discharge in relation to the total discharge exceeded 60% during all seasons in both basins.

Enhancing Heavy Crude Oil Flow in Pipelines through Heating-Induced Viscosity Reduction in the Petroleum Industry

The process of transporting crude oil across pipelines is one of the most critical aspects of the midstream petroleum industry. In the present experimental work, the effect of temperature, pressure drop, and pipe diameter on the flow rate of heavy crude oil have been assessed. Moreover, the total discharge and energy losses have been evaluated in order to demonstrate the improvements potentially achievable by using solar heating method replacing pipe, and adjusting the value of the initial pressure difference. Crude oil of API = 20 has been used for the experiments, with the studied pipelines sections connecting the separator unit to the storage tank operating at a temperature of 25°C–100°C, pressure drop of 3, 4, 5, and 6 kg/cm², and with pipe diameter of 4, 6, and 8 in. The results show that on increasing the temperature and/or the pressure drop, the flow rate through the pipeline becomes higher, thus raising the total pumping energy (as the pipe diameter increase), while energy losses increase from the last separator to the storage tank in the field. A pipe diameter increase can also produce a growth of the total pumping energy (i.e., energy losses increase). The results of the present analysis suggest that employing an optimal temperature (50°C) is needed to ensure good performance.

Retrospective analysis of burn patients presenting to the emergency department

Aim: Patients who applied to our emergency department due to burning trauma; it was aimed to analyze demographic characteristics such as age, gender, burn causes, burn rates, and degrees. Materials and Methods: Retrospectively analyzed data of patients who applied for burns within 3 years and were scanned from patient files and computer records. The age, gender, time and date of admission to the emergency department, causes of burns, anatomical burn localizations, total burned body surface areas, hospitalization, and discharge status of the cases were analyzed. Results: 56.1% of the patients included in the study were male and their mean age was 21.28 years. It was found that 49.7% of our patients were between the ages of 0-17. Boiling liquids are in the first place with a rate of 43.4% as the cause of burns. The average burned body surface area was 29%, and 3rd-degree burns were the most common. The most frequently affected body areas were the upper and lower extremities. The peak application season was seen in winter with a rate of 33.9%. Conclusion: It is known that burn cases always maintain their importance. Since it is a life-threatening health problem and it is frequently seen in the young-child age group, it is necessary to increase the precautions.

FLOODWALL: A Real-Time Flash Flood Monitoring and Forecasting System Using IoT

In recent years, flooding has become a major problem, encountered in many places all over the world, causing damage to property ranging from human life to economic losses. Floods cannot be prevented and eliminated, but the catastrophic damage caused by them can be mitigated. Floods can be predicted in advance with the help of emerging technologies, such as the Internet of Things (IoT). Using such technologies, the people can be warned in advance and evacuated from affected areas to safe places, along with their valuable possessions. In this context, a real-time application is required that can provide an early flood warning based on the seamless data received from IoT devices about various parameters. In this work, we have developed an IoT-based prototype to collect hydrological data of rivers, such as water flow, water level, and water discharge. The proposed system is also able to collect meteorological data, such as temperature, humidity, wind speed, and wind direction. Furthermore, the collected data have been analyzed and classified by using the long short-term memory (LSTM) model with water discharge, water level, rainfall, and temperature as input parameters. The LSTM model then classified the flood events either into “no alert,” “yellow alert,” “orange alert,” or “red alert.” As rivers have dynamic geographical features, measuring the total discharge of water becomes a complex task. To address this vulnerability, a novel approach for determination of water discharge using water flow, sectional area width, and sectional average depth is proposed. In addition, the difficulties in measuring the total amount of rainfall due to the erratic behavior of the weather conditions of the unique geographical location have been addressed. The system is found to accurately predict the flood event state with F1-score of 97% for “no alert,” 97% for “yellow alert,” 96% for “orange alert,” and 98% for “red alert.”

Depth of discharge characteristics and control strategy to optimize electric vehicle battery life

To comply with the global low-carbon green growth policy, the automobile industry is rapidly shifting from internal combustion engine to electric vehicles, which use high-Ni cathode active materials with high energy density, because mileage per charge is prioritized by the user. However, the high-Ni active material presents poor cycle characteristics because impurities generated by cation mixing increase the resistance and are also structurally unstable. Accordingly, the energy efficiency and safety of the battery were improved in this study by controlling the depth of discharge (DOD) in accordance with the state of health (SOH) of the battery. The charge/discharge characteristics and deterioration factors of 18,650 cylindrical batteries were investigated based on the set DOD conditions. The optimal DOD was set by analyzing the total discharge energy up to the end of life of the battery, Coulombic efficiency, internal resistance, Li plating, and the state of the positive electrode active material. Considering the optimal DOD setting conditions corresponding to the battery condition, DOD70 at 100–90 % SOH and DOD60 at 90–80 % SOH were found to be the most effective in terms of cycle characteristics and safety. The optimal DOD control method increased the total discharge energy by approximately 45 % relative to DOD60.

Variable load modes and operation characteristics of closed Brayton cycle pumped thermal electricity storage system with liquid-phase storage

As a new type of large-scale energy storage system, pumped thermal electricity storage (PTES) requires frequent load variation to smooth out grid fluctuations. However, there is a lack of research on the variable load of PTES systems. Therefore, five variable load methods are innovatively proposed in this paper, and the dynamic characteristics of the closed Brayton cycle PTES system with liquid-phase storage are simulated for variable load, separately. The results show that: for the same total air discharge time, during charge process, the rotor speed fluctuation rates of the five modes are “air charge + low-pressure and high-pressure sequential air discharge (CLHS)” (+0.80%), “air charge + low-pressure air discharge (CL)” (+1.07%), “air charge + high-pressure air discharge (CH)” (+1.40%), “air charge + high-pressure and low-pressure sequential air discharge (CHLS)” (+1.51%), “air charge + high-pressure and low-pressure simultaneous air discharge (CHL)” (+2.51%), from small to large. During discharge process, the rotor speed fluctuation rates are “CL” (-3.31%), “CHLS” (-3.96%), “CLHS” (-4.39%), “CH” (-5.61%), “CHL” (-9.83%), from small to large. During both charge and discharge processes, the load regulation ranges are “CHL”, “CLHS”/“CHLS”, “CH”, “CL”, from large to small. It can be seen that the modes with smaller rotor speed fluctuation rates also have smaller load regulation ranges, while the modes with larger load regulation ranges have larger rotor speed fluctuation rates. Therefore, in operation, different variable load modes should be selected according to the actual needs of rotor stability and load regulation range. The results of this study can provide a reference for the actual operation of pumped thermal electricity storage system.

Optimizing the geothermal potential of tunnel water by separating colder sectional discharges - Case study Brenner Base Tunnel

The use of geothermal energy from tunnels offers an environmentally friendly option for heating and cooling of buildings in the vicinity of the tunnel structure. In the research project “Thermocluster”, the geothermal potential of the Brenner Base Tunnel (BBT) was analysed and the utilization of the low-temperature heat to the city of Innsbruck was evaluated. A possible optimization on the geothermal performance was explored by separating colder sectional discharges from the total tunnel water drainage system. Further, the use of decentralized and centralized heat pumps, as well as heat distribution with different district heating networks (local low temperature heating and cooling networks, low-temperature network, classic district heating network), was investigated using process simulation. The results indicate that an optimization of the temperature of a subset of the total tunnel water discharge is possible. Furthermore, it could be shown that wide fluctuations in the efficiency of the heat pump can be expected. In addition, a rough cost estimation regarding the installation and distribution costs of the tunnel heat with different heat network variants is provided. This shows that the variant using decentralized heat pumps in the buildings and distribution via an anergy network is the most favourable in terms of installation.

Impact of Race/Ethnicity on Hospital Resource Utilization After Elective Anterior Cervical Decompression and Fusion for Degenerative Myelopathy.

With the advent of bundled care payments for spine surgery, there is increasing scrutiny on the costs and resource utilization associated with surgical care. The purpose of this study was to compare (1) the total cost of the hospital episode of care and (2) discharge destination between White, Black, and Hispanic patients receiving elective anterior cervical decompression and fusion for degenerative cervical myelopathy (DCM) in Medicare patients. The 2019 Medicare Provider Analysis and Review Limited Data Set and the 2019 Impact File were used for this project. Multivariate models were created for total cost and discharge destination, controlling for confounders found on univariate analysis. We then performed a subanalysis for differences in specific cost-center charges. There were 11,506 White (85.4%), 1,707 Black (12.7%), and 261 Hispanic (1.9%) patients identified. There were 6,447 males (47.8%) and 7,027 females (52.2%). Most patients were between 65 to 74 years of age (n = 7,101, 52.7%). The mean cost of the hospital episode was $20,919 ± 11,848. Most patients were discharged home (n = 11,584, 86.0%). Race/ethnicity was independently associated with an increased cost of care (Black: $783, Hispanic: $1,566, P = 0.001) and an increased likelihood of nonhome discharge (Black: adjusted odds ratio: 1.990, P < 0.001, Hispanic: adjusted odds ratio: 1.822, P < 0.001) compared with White patients. Compared with White patients, Black patients were charged more for accommodations ($1808), less for supplies (-$1780), and less for operating room (-$1072), whereas Hispanic patients were charged more ($3556, $7923, and $5162, respectively, P < 0.05). Black and Hispanic race/ethnicity were found to be independently associated with an increased cost of care and risk for nonhome discharge after elective anterior cervical decompression and fusion for DCM compared with White patients. The largest drivers of this disparity appear to be accommodation, medical/surgical supply, and operating room-related charges. Further analysis of these racial disparities should be performed to improve value and equity of spine care for DCM.

Estimation of stream water components and residence time in a permafrost catchment in the central Tibetan Plateau using long-term water stable isotopic data

Abstract. Global warming has significantly impacted the hydrological processes and ecological environment in permafrost regions. Mean residence time (MRT) is a fundamental catchment descriptor that provides hydrological information regarding storage, flow pathways, and water source within a particular catchment. However, water stable isotopes and MRT have rarely been investigated due to limited data collection in the high-altitude permafrost regions. This study uses the long-term stable isotopic observations to identify runoff components and applied the sine-wave exponential model to estimate water MRT in a high-altitude permafrost catchment (5300 m a.s.l.) in the central Tibetan Plateau (TP). We found that the isotope composition in precipitation, stream, and supra-permafrost water exhibited obvious seasonal variability. The freeze–thaw process of the permafrost active layer and direct input of precipitation significantly modified the stable isotope compositions in supra-permafrost and stream water. The hydrograph separation revealed that precipitation and supra-permafrost water accounted for 35 ± 2 % and 65 ± 2 % of the total discharge of stream water, respectively. MRT for stream and supra-permafrost water was estimated at 100 and 255 d, respectively. Such shorter MRTs of supra-permafrost and stream water (compared to the non-permafrost catchments) might reflect the unique characteristics of the hydrological process in permafrost catchments. Moreover, the MRT of supra-permafrost water was more sensitive to environmental change than that of stream water. Climate and vegetation factors affected the MRT of stream and supra-permafrost water mainly by changing the thickness of the permafrost active layer. Our results suggest that climate warming might retard the rate of water cycle in permafrost regions. Overall, our study expands our understanding of hydrological processes in high-altitude permafrost catchments under global warming.

CHANGING CLIMATE IN THE POTOHAR REGION- PUNJAB AND ITS EFFECT ON STREAMFLOW: A CASE STUDY OF KANSHI RIVER

&#x0D; &#x0D; &#x0D; The current study is to identify and examine the impacts of climate change on the water runoff in the Kanshi catchment of the Potohar Plateau region for 50 years from 1961-2010. Simple linear regression and Pearson correlation were used to assess the correlation coefficient, trend magnitude, and variability of temperature, rainfall, and stream. The results revealed that mean and maximum annual temperature steady and significant increase at the rate of 0.06 °C and 0.053/year during the last two decades. The rainfall pattern was also declined at the rate of -6.821, -0.018, -1.458 and -4.409 mm/year in winter, summer, autumn and spring steadily. Similarly, in August and September, the total water discharge had a significant and negative trend with p values 0.08 and 0.03 during 1991-2010. This substantial and significant change resulted from climate change or increased intercession of anthropogenic activities on the earth's surface.&#x0D; &#x0D; &#x0D;

1656. Impact of Pharmacist Intervention on Antibiotic Prescribing at Hospital Discharge for Community-Acquired Pneumonia, Urinary Tract Infection, and Skin and Soft Tissue Infections

Abstract Background The high incidence of suboptimal antibiotic use at transitions of care represents a novel area for antimicrobial stewardship for community-acquired pneumonia (CAP), urinary tract infection (UTI), and skin and soft tissue infections (SSTIs). The objective of this study was to investigate the role of a pharmacist intervention at discharge to improve antibiotic use. Methods This was a single-center, retrospective, crossover analysis of patients admitted to general medicine units from 11/1/21 to 3/31/22 with a diagnosis of CAP, UTI, or SSTI. The study was divided into two phases separated by a one-month washout. Each two-month phase included two pre-specified units, an intervention and control. During phase 2, the intervention and control units were switched. Patients on antibiotics identified for discharge were reviewed and interventions were communicated by the pharmacist to the provider. Interventions were made based on predefined guidance for oral step-down therapy and total duration. The primary outcome, discharge antibiotic days of therapy (DOT), was compared between the intervention and control cohorts. Secondary outcomes included total DOT, hospital length of stay (LOS), 30-day readmission, and appropriateness of drug selection, dose, and duration. Results Records of 161 patients were included in this study, 85 in the intervention cohort (47 in phase 1, 38 in phase 2) and 76 in the control (41 in phase 1, 35 in phase 2). Overall discharge DOT was 3 (IQR 0–4.5) in the intervention cohort and 3 (IQR 0-5) in the control cohort (P = 0.8), and overall total DOT was 7 (IQR 5-9) and 7 (IQR 5-10) respectively (P = 0.27). Patients in the intervention group were more likely to have appropriate total duration (61.2% vs 44.7%, P = 0.001) and discharge duration of antibiotics (67.1% vs 53.9%, P = 0.013) for all three indications based on predefined guidance. Hospital LOS was 4 (IQR 3-5) vs 5 days (IQR 3-6.3) in the intervention and control cohorts (P = 0.001) respectively, and a lower 30-day readmission (14.1% vs. 23.7%, resp.). Conclusion Despite similar antibiotic DOTs, pharmacist intervention at discharge appeared to improve overall antibiotic total duration and discharge duration for CAP, UTI, and SSTI. Opportunities to improve discharge stewardship processes should be further explored. Disclosures Joseph L. Kuti, PharmD, Abbvie: Honoraria|bioMeriuex: Advisor/Consultant|bioMeriuex: Grant/Research Support|Contrafect: Grant/Research Support|Entasis: Grant/Research Support|Merck and Co: Grant/Research Support|Roche Diagnostics: Grant/Research Support|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|Shionogi: Honoraria|Summit: Grant/Research Support David P. Nicolau, PharmD, Shionogi: Grant/Research Support.

Improved Darcian streambed measurements to quantify flux and mass discharge of volatile organic compounds from a contaminated aquifer to an urban stream

Quantifying VOC transport from contaminated groundwater to streams is challenging and important for understanding off-site migration of VOCs, cross-media contamination (groundwater to surface water and eventually air), and potential impacts on downstream ecosystems and human populations. A streambed point sampling approach was used to quantify fluxes of water and 14 VOCs from groundwater to an urban stream in North Carolina, USA, during summer (June 2015) and winter (January 2016). The approach is unique in coupling measurements of vertical hydraulic conductivity, vertical hydraulic head gradient, and groundwater VOC concentration at each individual sampling point, reducing or eliminating some potential concerns with other Darcian methods for quantifying VOC inputs to streams.Most results were consistent with discharge of two main VOC plumes on opposite sides of the stream. Plume 1 from the west side was dominated by cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC) at mean concentrations of 19 and 11 μg L−1, respectively. Plume 2 from the east side was dominated by benzene (mean concentration 56 μg L−1). Plume 2 was not previously known, and the improved sampling approach allowed VOC discharge from both plumes to be quantified simultaneously.For 13 of the 14 detected VOCs, the mean VOC flux from groundwater to the stream (fVOC) was higher in January 2016 than in June 2015, mainly because groundwater flux was higher in January. The only exception was cDCE, the most abundant VOC in Plume 1, which had mean fVOC values of 9.8 and 9.5 mg m−2 d−1 in June 2015 and January 2016, respectively. Benzene was the most abundant VOC in Plume 2 and had mean fVOC values of 11 and 37 mg m−2 d−1 in June 2015 and January 2016, respectively. High groundwater flux drove almost all the occurrences of high VOC flux. For a given VOC, the flow-weighted mean concentration (with each VOC concentration weighted by the upward groundwater flux at the VOC sampling point) was generally larger than the unweighted mean concentration. Thus, flow-weighting of concentrations gave a more accurate indication of the average VOC concentration in net groundwater discharge to the stream.An estimate of total VOC mass discharge from groundwater to the study reach of the stream, 3.6 kg of VOC per year, was based on the fVOC results and streambed area in the reach. The bulk of this discharge was due to benzene, cDCE, and VC, with individual mass discharges of 2.1, 0.83, and 0.40 kg yr−1, respectively. Estimates of maximum potential VOC degradation in the streambed suggest that the 3.6 kg yr−1 estimate of mass discharge was not sensitive to potential degradation of VOCs in the streambed sediments above the groundwater sampling depth.