Mass Discharge Research Articles

Integrated hydrogeophysical modelling and data assimilation for geoelectrical leak detection

Time-lapse electrical resistivity tomography (ERT) measurements provide indirectobservations of hydrological processes in the Earth's shallow subsurface at high spatial and temporal resolution. ERT has been used in the past decades to detect leaks and monitor the evolution of associated contaminant plumes. Specifically, inverted resistivity images allow visualization of the dynamic changes in the structure of the plume. However, existing methods do not allow the direct estimation of leak parameters (e.g. leak rate, location, etc.) and their uncertainties. We propose an ensemble-based data assimilation framework that evaluates proposed hydrological models against observed time-lapse ERT measurements without directly inverting for the resistivities. Each proposed hydrological model is run through the parallel coupled hydro-geophysical simulation code PFLOTRAN-E4D to obtain simulated ERT measurements. The ensemble of model proposals is then updated using an iterative ensemble smoother. We demonstrate the proposed framework on synthetic and field ERT data from controlled tracer injection experiments. Our results show that the approach allows joint identification of contaminant source location, initial release time, and solute loading from the cross-borehole time-lapse ERT data, alongside with an assessment of uncertainties in these estimates. We demonstrate a reduction in site-wide uncertainty by comparing the prior and posterior plume mass discharges at a selected image plane. This framework is particularly attractive to sites that have previously undergone extensive geological investigation (e.g., nuclear sites). It is well suited to complement ERT imaging and we discuss practical issues in its application to field problems.

Understanding the interrelationships among mass balance, meteorology, discharge and surface velocity on Chhota Shigri Glacier over 2002–2019 using in situ measurements

AbstractThe Himalayan glaciers contribute significantly to regional water resources. However, limited field observations restrict our understanding of glacier dynamics and behaviour. Here, we investigated the long-term in situ mass balance, meteorology, ice velocity and discharge of the Chhota Shigri Glacier. The mean annual glacier-wide mass balance was negative, −0.46 ± 0.40 m w.e. a−1 for the period 2002–2019 corresponding to a cumulative wastage of −7.87 m w.e. Winter mass balance was 1.15 m w.e. a−1 and summer mass balance was −1.35 m w.e. a−1 over 2009–2019. Surface ice velocity has decreased on average by 25–42% in the lower and middle ablation zone (below 4700 m a.s.l.) since 2003; however, no substantial change was observed at higher altitudes. The decrease in velocity suggests that the glacier is adjusting its flow in response to negative mass balance. The summer discharge begins to rise from May and peaks in July, with a contribution of 43%, followed by 38% and 19% in August and September, respectively. The discharge pattern closely follows the air temperature. The long-term observation on the ‘Chhota Shigri – a benchmark glacier’, shows a mass wastage which corresponds to the slowdown of the glacier in the past two decades.

Field Demonstration of the Horizontal Treatment Well (HRX Well®) for Passive In Situ Remediation

AbstractThe horizontal reactive media treatment well (HRX Well®) uses directionally drilled horizontal wells filled with a treatment media to induce flow‐focusing behavior created by the well‐to‐aquifer permeability contrast to passively capture proportionally large volumes of groundwater. Groundwater is treated in situ as it flows through the HRX Well and downgradient portions of the aquifer are cleaned via elution as these zones are flushed with clean water discharging from the HRX Well. The HRX Well concept is particularly well suited for sites where long‐term mass discharge control is a primary performance objective. This concept is appropriate for recalcitrant and difficult‐to‐treat constituents, including chlorinated solvents, per‐ and polyfluoroalkyl substances (PFAS), 1,4‐dioxane, and metals. A full‐scale HRX Well was installed and operated to treat trichloroethene (TCE) with zero valent iron (ZVI). The model‐predicted enhanced flow through the HRX Well (compared to the flow in and equivalent cross‐sectional area orthogonal to flow in the natural formation before HRX Well installation) and treatment zone width was consistent with flows and widths estimated independently by point velocity probe (PVP) testing, HRX Well tracer testing, and observed treatment in downgradient monitoring wells. The actual average capture zone width was estimated to be between 45 and 69 feet. Total TCE mass discharge reduction was maintained through the duration of the performance monitoring period and exceeded 99.99% (%). Decreases in TCE concentrations were observed at all four downgradient monitoring wells within the treatment zone (ranging from 50 to 74% at day 436), and the first arrival of treated water was consistent with model predictions. The field demonstration confirmed the HRX Well technology is best suited for long‐term mass discharge control, can be installed under active infrastructure, requires limited ongoing operation and maintenance, and has low life cycle energy and water requirements.

Fate and migration of polybrominated diphenyl ethers in a workshop for waste printed circuit board de-soldering.

Polybrominated diphenyl ethers (PBDEs) are released from the recycling process of PBDE-containing waste printed circuit board (WPCB), but studies on the mechanism of PBDE emission and migration are limited. In this study, PBDE concentrations in particulate matter (PM), dust, and fumes collected in a pilot-scale workshop for the WPCB de-soldering process were measured, and PBDE emission after gas treatment was estimated. The results showed that the mean concentrations of ∑8PBDEs in TSP and PM2.5 in the workshop were 20.3 ng/m3 (24.7 μg/g) and 16.1 ng/m3 (115 μg/g), respectively. In practice, the fumes containing gaseous and particulate PBDEs were treated by the combination of alkaline solution absorption and activated carbon adsorption. Compared to PBDE concentration in workshop floor dust (2680 ng/g), PBDE concentrations in solution scum (68,000 ng/g) and hood inside dust (20,200 ng/g) were condensed. The concentrations of ∑6PBDEs at the stack outlet (416 pg/m3) after gas treatment were lower than those in the stack pipe (1310 pg/m3) and hood inside (7440 pg/m3). The PBDEs in fumes were removed through physical adsorption of alkaline solution and activated carbon, and solution scum constituted the main mass discharges of PBDEs. The emission factor of PBDEs at the stack outlet was 47.3 ng ∑6PBDEs/kg WPCB. As a result, the WPCB de-soldering process is an important source of PBDE pollution, and gas treatment of solution absorption and activated carbon adsorption can reduce PBDE emission to some extent.

Numerical characterization of transient two-phase flow of nozzle under the impact of diesel fuel temperature and injector backpressure

The inner fluid flow within the micro-sac injector is investigated numerically via AVL-Fire CFD code particularly in a microscale dimension of nozzle hole is carried out in the present work. The structural parameters of the injector are left unchanged, while the physical properties of the fluid such as pressure gradient and fluid temperature are taken into account to survey their influence on vapor volume fraction evolution, vapor mass flow rate, cavitation inception, and discharge coefficient. The reliability of modeling results is confirmed by comparing obtained data with experimental one and numerical results of Payri et al. and a close match served as an indication for the accuracy of the methodology. The multiphase modality is activated for the two-fluid model application in the nozzle segment, while the interfacial source term accounts for the momentum exchange of phases in the cavitation drag model. According to results, increasing the fuel temperature is a factor for increasing turbulent kinetic energy; meanwhile, vapor volume fraction at different times shows a different trend. Concerning the discharge coefficient, it seems that increasing the fluid temperature reduces this parameter. In contrast, increasing the pressure gradient leads to a considerable increase in the discharge coefficient.

Implementation of a triage system in the Alerta Rosa breast cancer navigation program.

e19064 Background: Alerta Rosa is a navigation program in Nuevo Leon, Mexico that aims to reduce delays in breast cancer (BC) diagnosis and treatment initiation irrespective of healthcare coverage. Via a call center, a navigator registers each patient’s initial concern and schedules a medical evaluation. This study aimed to assess the implementation of a triage system to guide appointment prioritization for undiagnosed BC patients with abnormal breast findings or imaging studies. Methods: Women that contacted Alerta Rosa were stratified according to their clinical characteristics into three priority groups. Asymptomatic women seeking check-up information were classified as low-priority (“Green”), those with nonspecific symptoms (e.g. mastalgia) or indeterminate image studies (BIRADS 0) as intermediate-priority (“Yellow”), and patients with suspicious symptoms (i.e. palpable mass, nipple retraction or bloody discharge), abnormal image studies (BIRADS 3-5) or an established BC diagnosis as high-priority (“Red”) for an appointment. The triage system’s ability to detect undiagnosed BC was evaluated against the number of patients per category in whom BC was later confirmed. Differences in time from initial contact to first medical evaluation were explored with an independent t-test. Results: From December 2017 to 2019, 561 women with a median age of 44 years (range: 8-89) contacted Alerta Rosa. 369 (66%) reported breast symptoms, 92 (16%) sought check-up information, 68 (12%) had an indeterminate/abnormal image study and 32 (6%) had received a BC diagnosis and wanted a second opinion. Accordingly, 16% of patients were classified as “Green”, 25% “Yellow” and 59% “Red”. The median time from stratification to medical evaluation was 4 days for the “Red” group and 7 days for those in other categories ( p= 0.003). A total of 558 appointments were scheduled, of which 441 (79%) were attended. Excluding those who had received a prior BC diagnosis, 20/299 patients from the “Red” group had BC confirmed (6.7%) compared to 1/138 patient from the “Yellow” (0.7%) and none from the “Green” categories. Therefore, the “Red” category achieved a sensitivity of 95.2% (CI95%: 76.2-99.9%) and specificity of 53.8% (CI95%: 49.3-58.3%) for BC. Conclusions: The triage system adequately identified women with different probabilities of having BC. Thus, the implementation of a stratification system could help identify high risk patients in limited-resource settings where screening programs are ineffective and efforts to prioritize access to medical attention is crucial to achieve early-stage diagnoses.

Source- vs topographic-forcing in pyroclastic currents: the case of the Orvieto-Bagnoregio Ignimbrite, Vulsini, central Italy

The main pyroclastic flow unit of the Orvieto-Bagnoregio Ignimbrite (Vulsini, central Italy) provides a striking example of increasing thickness with distance from the vent, accompanied by opposite size-distance trends for lithic and juvenile clasts. Lithic clasts show normal lateral grading, while dense (1120-1400 kg/m 3 ) scoria clasts show inverse lateral grading. The latter trends are attributed to the opposite density contrast with respect to the flow medium of gas and fine particles and put a constraint to the minimum density of the transporting flow. Thus, the study example approaches the high-concentration, non-turbulent end-member of pyroclastic currents. By applying the topological aspect ratio approach, we infer a forced behavior of the parent flow in proximal to intermediate settings, due to sustained feeding with high mass discharge rate at source. In distal settings, the source-forced regime was enhanced by topographic forcing due to channeling along radial topographic lows, thus resulting in increasing bulk density and runout of the current. By analogy with the mobility of dry debris flows, the sliding component of transport prevailed in proximal to intermediate settings, accounting for the prevailing tendency of the pyroclastic current to transport than to deposit, thus forming a relatively thin deposit with normal lateral grading of lithics. The spreading component dominated downcurrent, resulting in increasing pyroclast accumulation (up to tens of meters of thickness) and delayed deposition of coarsest scoria clasts as far as the final runout.

Quantitative comparison of experimental and Mohr-Coulomb finite element method simulation flow characteristics from quasi two-dimensional flat-bottomed bins

Four different flow characteristics obtained from Eulerian finite element method (FEM) simulations using a Mohr-Coulomb material model are quantitatively compared to experiments performed on laboratory-scale concentric and eccentric quasi two-dimensional flat-bottomed bins. Particle image velocimetry (PIV) experiments are performed on Ottawa 20–30 sand discharging through the bins. The experimental steady state velocity profiles, mass discharge rate (MDR), duration of steady MDR (TSS), and free surface profiles are compared to the FEM predictions. The significance of material dilation and associated softening (DS) on FEM flow characteristics is examined through comparisons to simulations without dilation or softening (NDNS). FEM DS simulations using a Mohr-Coulomb material model that includes material dilation and softening are shown to be capable of predicting the four flow characteristics in both discharging bins with reasonable accuracy.

OPTIMIZATION OF THE VARIABLE REFRIGERANT FLOW SYSTEMS BY USE OF GENETIC ALGORITHM AND ENERGY, EXERGY, AND ECONOMIC ANALYSIS FOR THREE COOLANT FLUIDS

The current study aimed at investigation of the Variable Refrigerant Flow (VRF). Energy, exergy, and economic model for R11, R22, and R134a refrigerants. The genetic algorithm was used for optimization of the cycle. The objective functions in the current study were the second law efficiency and cooling cost. The cooling cost was a new economic function that was defined in this paper for the first time. Results showed that the highest Coefficient of Performance (COP) and second law’s efficiency as well as the lowest cooling cost and exergy loss belonged to the refrigerant R134a, and second and third to it were R11 and R22. The optimum values of condenser pressure and evaporators 1, 2, and 3 for the refrigerant R134a were 799.7, 706.2, 925.2, and 23122 (kPa), and the mass discharge of the evaporators 1 and 2, was 0.1 and 0.072 (kg/s).

Discharge characteristics of binary particles in a rectangular hopper with inclined bottom

The stable discharge of particles through the hopper plays a key role in many industrial applications. In order to investigate the discharge characteristics of binary particles in a rectangular hopper with an inclined bottom, the discrete element method (DEM) was used to simulate the discharge process. The accuracy of DEM was validated by comparing calculated and experimental values. The influences of geometric parameters (hopper width, orifice width, and hopper angle) and particle parameters (friction coefficient between particles, friction coefficient between particles and wall, fine particle mass fraction, and particle size ratio) on the discharge were studied. Some interesting results have been found that the effect of hopper width on discharge is minimal. The mass discharge rate is linearly related to the 3/2 power of orifice width, and it can be predicted by the modified Beverloo correlation which developed for a rectangular hopper with flat bottom. The mass discharge rate increases exponentially with the decrease in hopper angle, which is different from that of monosized particles. The mass discharge rate is more sensitive to low friction coefficient, and the friction coefficient between particles plays a leading role. Fine particles can promote the discharge process, and this effect is enhanced as particle size ratio increases.

Wasting the North Sea? – A field-based assessment of anthropogenic macrolitter loads and emission rates of three German tributaries

Research into the scope of litter pollution in freshwater systems has shown similar levels to the marine and coastal environment. Global model estimates of riverine emission rates of anthropogenic litter are largely based on microplastic studies as long-term and holistic observations of riverine macroplastics are still scarce. This study therefore aims to contribute a detailed assessment of macrolitter in the transitional waters of three major North Sea tributaries: Ems, Weser, and Elbe. Litter surveys were carried out in four river compartments: along the embankment, on the river surface, in the water column, and on the river bed. The data revealed spatio-temporal variability and distinct pollution levels for each compartment. Beaches had the highest debris diversity and were significantly more littered than vegetated sites and harbors. Stony embankments were least polluted. Benthic litter levels appeared substantial despite rapid burial of objects being likely due to high suspended sediment loads. Two extrapolation approaches were tested to scale daily and annual litter emission quantities of surface- and subsurface-floating litter. Using the mean (median) litter item mass from water column samples, total annual mass discharges were calculated: ∼0.9 (0.2) t y−1 to ∼2.8 (0.5) t y−1 emitted via the Ems, ∼1.3 (0.2) t y−1 to ∼12.0 (1.9) t y−1 through the Weser, and ∼14.7 (2.4) t y−1 to ∼801 (128) t y−1 carried into the North Sea by the Elbe. These rates deviate considerably from previous model estimates of plastic loads discharged by these three rivers. Future studies should therefore ground-truth model estimates with more river-specific and long-term field observations. Overall, the estimated plastic debris discharge quantities account for <1% of the total mass of mismanaged plastic waste per catchment.

The Challenge of Die Filling in Rotary Presses-A Systematic Study of Material Properties and Process Parameters.

For the efficient and safe production of pharmaceutical tablets, a deep process understanding is of high importance. An essential process step during tableting is the die filling, as it is responsible for a consistent tablet weight and drug content. Furthermore, it affects the results of subsequent process steps, compaction and ejection, and thus critical quality attributes. This study focuses on understanding the influences of process parameters and material properties on die filling on a rotary tablet press. By the systematic variation in process parameters as the turret and paddle speeds as well as the fill and dosing depths, five formulations with differing properties are processed. Analysis of the normalized tablet weight, called filling yield, revealed different limitation mechanisms of the filling process, i.e., incomplete filled dies for certain parameter settings. Kinetic limitations occur due to a short residence time under the feed frame (filling time) caused by high turret speeds, which additionally induce high tablet weight variation coefficients. Characteristic maximum turret speeds at certain paddle speeds can be found to still achieve complete filling. At low turret speeds, densification of the powder inside the dies takes place, induced by two mechanisms: either high paddle speeds or high overfill ratios, or a combination of both. The challenge to fill the dies completely as well as avoid densification is dependent on material properties as the flowability. The mass discharge rate from an orifice was found to be in a linear correlation to the filling results of different formulations below complete filling.

Evidence of Spatio‐Temporal Variations in Contaminants Discharging to a Peri‐Urban Stream

AbstractXenobiotic organic compounds can be discharged from contaminated groundwater inflow and may seep into streams from multiple pathways with very different dynamics, some not fully understood. In this study, we investigated the spatio‐temporal variation of chlorinated ethenes discharging from a former industrial site (with two main contaminant sources, A and B) into a stream system in a heterogeneous clay till setting in eastern Denmark. The investigated reach and near‐stream surroundings are representative of peri‐urban settings, with a mix of high channel alteration and more natural stream environment. We therefore propose an approach for risk assessing impacts arising from such complex contamination patterns, accounting for potential spatio‐temporal fluctuations and presence of multiple pathways. Our study revealed substantial variations in pathway contributions and overall contaminant mass discharge to the stream. Variable contaminant contributions arising from both groundwater seepage and urban drains were identified in the channelized part of the north stream, primarily from source A. Furthermore, variations in the hyporheic and shallow groundwater flows were found to enhance contaminant transport from source B. These processes result in an increase of the overall mass of contaminant discharged, correlating with the channels' flow. Thus, an in‐stream control plane approach was found to be an effective method for integrating multiple and variable discharge contributions quantitatively, although information on specific contaminant sources is lost. This study highlights the complexity and variability of contaminant fluxes occurring at the interface between groundwater and peri‐urban streams, and calls for the consideration of these variations when designing monitoring programs and remedial actions for contaminated sites with the potential to impact streams.

Disaggregating Landscape‐Scale Nitrogen Attenuation Along Hydrological Flow Paths

AbstractEvaluating how nitrogen (N) sources are attenuated throughout the landscape is critical to further our understanding of catchment‐scale N budgets. We developed a catchment‐scale N budget for a mixed land use karst springshed using in situ measurements (nitrate leaching fluxes and attenuation) and long‐term records (surface N inputs and spring exports) to estimate 20‐year average landscape‐scale N loading, attenuation, and export. We introduce a conceptual model framework to compute N export that can be applied consistently for point or nonpoint sources. The model is based on the product of only four components for each N source: population density or proportion of land cover, P; specific load, L; anthropogenic attenuation, A; and natural attenuation, N. The product of these components is computed for each N source and then integrated at the basin scale. The concise PLAN model framework predicted attenuation of 90% ± 3% of N inputs, in close agreement with the estimate based on measured spring mass discharge (87% ± 3%). Further, when this attenuation is disaggregated along the hydrological flow path, we estimate that 64% of inputs are lost in the surface soil, 20% in the vadose zone, and 6% in the aquifer. Livestock and human wastes were estimated to be the dominant contributors to spring N export, which was independently supported by isotopic data. The PLAN model is a simple, transferable framework that supports systematically computing N export based on proportioning of load and attenuation. Identifying the main sources of N ultimately contributing to discharged N loads is a critical step toward source‐related water‐quality management.

Encapsulated Papillary Carcinoma of the Breast: A Series of 7 Cases

Background: Encapsulated papillary carcinoma (EPC) is a rare tumor and accounts for 1-2% of all breast cancers [1]. There are pure EPC, or associated with ductal carcinoma in situ (DCIS) and/or invasive carcinoma of no special type (NST). It occurs most frequently in women at post-menopausal period. Clinically, patient presents with palpable mass or bloody nipple discharge. It may also manifest as asymptomatic lesion identified at screening mammography. The management of this type of tumor is not standardized [2]. Surgical treatment may be conservative or radical with adjuvant therapy consisting of radiotherapy (RT), hormonotherapy (HT) and sometimes chemotherapy (CT). We recently treated a young 35-year-old patient with EPC with high grade triple negative invasive component. We focused on different EPC we managed these past years.

Surfactant flooding makes a comeback: Results of a full-scale, field implementation to recover mobilized NAPL

Non-aqueous phase liquid (NAPL) remediation techniques using surfactants, such as enhanced pump and treat (also known as Surfactant–Enhanced Aquifer Remediation, “SEAR”) and micellar flooding provide a faster and more efficient way to recover NAPL from the subsurface. Micellar flooding is a recovery technique that relies on the ability of surfactants to mobilize the NAPL phase by reducing the interfacial tension between the aqueous phase and the NAPL. The application of micellar flooding for NAPL recovery has been limited to laboratory studies and some pilot–scale field applications primarily due to concerns that the technology might lead to uncontrolled movement of NAPL. This paper presents results from a full-scale field application of the micellar flood process designed to mobilize and recover an LNAPL (Jet fuel) from a surficial sandy aquifer located at a tank facility in western Jutland, Denmark. Phase behavior and flow experiments were conducted with field samples to identify suitable surfactant formulations. A field–scale simulation model was developed that indicated that a line–drive pattern with hydraulic control wells would be optimal for NAPL recovery. In addition to monitoring during the field implementation, monitoring was conducted immediately after and for a period of >1 year. The field implementation resulted in >90% recovery (approximately 36,000 Kg of LNAPL) based on the mass balance using laser–induced fluorescence (LIF) and chemical soil analysis (total petroleum hydrocarbon or TPH and BTEX) data. Post–surfactant flood site monitoring consisted of sampling water from multi–levels and from recovery wells. Groundwater samples were analyzed for total petroleum hydrocarbon (TPH) and benzene, toluene, ethylbenzene and xylene (BTEX). The pre–treatment and post–treatment mass discharges were also monitored, which led to a relationship between mass discharge with the mass reduction in the source zone. Also, the mass discharge Γ–model commonly used for DNAPL modeling was successfully implemented for LNAPL remediation. Studies of field applications of surfactant remediation processes are not readily available; it is especially rare to present a study of micellar flooding implementation for full-scale remediation processes.

Quantitative relationship between plume emission and multiple deflations after the 2014 phreatic eruption at Ontake volcano, Japan

The phreatic eruption of Mount Ontake in 2014 caused local-scale subsidence and a mass discharge of water–vapor plumes from vents. A previous study of InSAR data analysis modeled the local subsidence as a deflation of a shallow hydrothermal reservoir (~ 500 m beneath the vents), and speculated that it was associated with plume emission continuing just after the eruption. In addition, combination of the InSAR and GNSS data implies that another, deeper deflation source (~ 3–6 km beneath the vents) contributes to the baseline contraction of the GNSS data. In this study, we estimated daily mass flux of the emitting plumes using photographed images, and compared the temporal behavior of the discharged mass with that of deflation of the two sources in order to clarify their association. The temporal profiles of the shallow deflation volume and the discharge mass both show evidence of decay, but with different characteristics; the deflation volume progress was approximated by a single exponential decay with a long relaxation time (379–641 days), whereas the discharge mass displayed a sum of a linear trend and an exponential decay with shorter relaxation time (47 days). This discrepancy, along with GNSS data, suggests the contribution of a deep deflation source with a short relaxation time (20–40 days). Estimation of mass balance between the emitting plume and fluids discharged from both shallow and deep sources revealed that more than 70% of the discharged mass came from the deep source. Based on the estimated mass balance, phase state of the shallow reservoir was estimated as a single-phase, liquid-rich reservoir. The fast decay of the deep deflation may reflect rapid depressurization due to violent fluid discharge at the onset of the eruption. In contrast, the slow decay of the shallow deflation suggests that it had a minor role in the eruption. However, such a wet reservoir has the potential to induce volcanic hazard such as snow-melting lahar for future eruptions, requiring monitoring the volcano, which will probably shift to pre-eruptive re-pressurized phase, until the future eruption.

Modelling and physico-chemical constraints to the 4.5 ka Agnano-Monte Spina Plinian eruption (Campi Flegrei, Italy)

The 4.5 ka trachytic Plinian eruption of Agnano-Monte Spina is the largest magnitude event of the past 5 ka at Campi Flegrei caldera. The complete eruptive sequence consists of six members, three of which, named A, B and D, are characterized by the association of fallout and pyroclastic density current (PDC) deposits well preserved at proximal locations.In this study, we analyze the textural characteristics of the pumice clasts of the three major fallout deposits (A1, B1, D1) and of their associated PDC deposits (A2, B2, D2), and link them to the physical properties of magma in order to investigate conduit fluid dynamics. A combination of data (field work, grain-size and density measurements, vesicle number densities and size distributions, crystal content, water content) is used to set up the source term conditions for numerical simulations.Each fall/PDC transition is accompanied by distinctive changes in textural properties of the juveniles, recognized by a lowering in vesicle number densities of about one order of magnitude (from 108 to 107cm−3), indicating a significant decrease in the magma ascent rate. Melt inclusions show a marked decrease in volatile content recurrent at each fall/PDC transition and indicate that the three main pulses of the eruption were fed by distinct and progressively deeper magma batches. Numerical simulations, taking into account magma properties derived from the textural analyses, and variations in initial water content, show decreases in the exit velocities and Mass Discharge Rate (MDR) consistent with such fall/PDC transitions. Different initial water contents together with changes in conduit diameters allow us to simulate the different column heights reconstructed for the three Plinian phases. The reconstructed scenario for the Agnano-Monte Spina eruption involves a stop-start behavior and a top-down trigger for the most voluminous and intense eruptive episode D.

Herlyn-Werner-Wunderlich Syndrome with Central Precocious Puberty: A Case Report

Herlyn-Werner-Wunderlich (HWW) syndrome is a rare congenital anomaly of the genitourinary tract comprising uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis. Patients with HWW syndrome usually present symptoms such as dysmenorrhea, abdominal pain, pelvic mass, and purulent vaginal discharge. If not treated at an appropriate time, complications such as infertility, endometriosis, pyosalpinx, and subsequent pelvic adhesions may occur. Here, we report a case of HWW syndrome in a 7-year-old-girl who was also diagnosed as having central precocious puberty. She was brought to the pediatric department with chief complaints of lump in her breast and vaginal discharge. When she was around 2 months old, she was confirmed to have a single kidney on ultrasonography. We checked her past medical history and diagnosed her as having HWW syndrome based on the results of imaging studies, including abdominal ultrasonography and pelvic magnetic resonance imaging. She underwent treatment with gonadotropin-releasing hormone analogue for 2 years. During 24 months of follow-up, she showed no serious problems or complications. If renal anomalies are identified immediately after birth or in infancy, further screening tests should be conducted prior to menstruation for determining congenital abnormalities of the reproductive tract and vice versa. Key words: HWW syndrome, Central precocious puberty, Renal agenesis, Hemivagina, Uterus didelphys

2117 Anal Squamous Cell Carcinoma Presenting as a Rectal Mass

INTRODUCTION: Anal squamous cell carcinoma (SCC)typically presents as an anal mass. It rarely presentsin the rectumalone. Limited literature exists to discuss regarding optimal management for this unique presentation. We present a patient withanal SCC manifesting as a rectal mass and reviewher management. CASE DESCRIPTION/METHODS: A 73 year-old woman with esophageal reflux presented to our office with chronicrectal bleedingand constipation.She denied anal pain. Colonoscopy revealed a 1.2 cm massin the anterior rectum, 2 cm from the anal verge (Figure 1). Biopsies revealed focally invasive nonkeratinizing SCC (Figure 2). On rectal endoscopic ultrasound (EUS), the mass was confined to the anus andextended from the anorectal canal into the rectum (Figure 3). Submucosal invasion was noted, but not through the rectal muscularis propria. PET CT showed no perirectal invasion, lymphadenopathy, metastatic disease orother sources of primary SCC. Final staging was T2N0. She underwentchemoradiationwith5-fluorouricil and mitomycin. Surgery was deferred to preserve anal function.Her tumor showed a complete response after 6 weeks and she is currently being followed with routine surveillance. DISCUSSION: Anal SCC makes up2.6% of digestive system cancers in the United States, but its incidence is rising in men and women, possibly due to changes in sexual behavior and increasing rates of HPV exposure. Gastroenterologists should recognizeatypical presentations ofanal SCC, especially in high-risk populations: men who have sex with men, HIV positive patients, and women with high risk HPV. Rectal bleeding and altered bowel habits arethe most commonlyreported symptoms. Other symptoms include anal mass, pain, itching, and mucous discharge, but up to 20% of patients with anal cancer are asymptomatic. The absence of anal pain and external lesions as well as the rectal mass on in our patient suggested an alternative diagnosis. Given that management of rectal cancer has traditionally centered around resection, this emphasizes the utility of EUS to make the correct diagnosis and direct management. The management of this unique presentation of anal SCC has not been fully established, but our patient received standard chemoradiation with good results. Anal SCC has a range of presentations and can present as a rectal mass. Given that anal SCC rates are increasing, our case highlights the importance of disease screening, recognition, and prevention.