Narrow Inlet Research Articles

Temporal and Spatial Variations in Water Quality on New York South Shore Estuary Tributaries: Carmans, Patchogue, and Swan Rivers

The chemical and biological impacts of anthropogenic physical modifications (i.e., channelization, dredging, bulkhead, and jetty construction) to tributaries were assessed on New York’s Long Island South Shore Estuary. Water-quality data collected on Carmans, Patchogue, and Swan Rivers from 1997 to 2005 indicate no significant differences in nutrient levels, temperature, or pH among the rivers, but significant differences in light transmittance, dissolved oxygen (DO), salinity, and sediments were observed. Patchogue River (PR) and Swan River (SR) were significantly more saline than Carmans River (CR), PR and SR had less light transmittance than CR, and both exhibited severe warm season hypoxia. CR was rarely hypoxic and only at the lower layer of the deepest station in warm seasons. Deep stations on PR had hypoxic readings year round, but the shallower SR was well-oxygenated at all stations after the fall turnover. There were wide diel and seasonal variations in chlorophyll a on each river, and measurements were significantly higher at poorly flushed stations. In warm seasons, this often resulted in hyperventilation with supersaturated DO in the upper water column on sunny days, and suboxic conditions at nights and/or in deeper layers. PR sediments were anoxic, SR sediments ranged from normal to anoxic, and CR sediments were normal at all stations. Polyaromatic hydrocarbon concentrations in PR sediments were over three orders of magnitude higher than SR and CR sediments. Benthic invertebrate assessment of species richness, biotic index, and Ephemeroptera, Plecoptera and Trichoptera richness indicated that PR was severely impacted, SR ranged from slightly to severely impacted, and CR ranged from non-impacted to slightly impacted. Diversity and abundance of plankton were comparable on SR and CR, and were significantly higher than on PR. The data indicate that nutrients do not play a major role in hypoxia in these estuarine tributaries but that physical forces dominate. The narrow inlets, channelization, and abrupt changes in depth near the inlets of PR and SR foster hypoxic conditions by inducing salinity stratification that limits vertical mixing and by restricting horizontal water mass exchange with the bay. The study suggests that other tributaries with such physical modifications should be examined to assess the temporal and spatial extent of hypoxia.

Eco-Hydraulics Techniques for Controlling Eutrophication of Small Scenery Lakes—A Case Study of Ludao Lake in Shanghai

The Ludao Lake with an area of 0.86 km 2 and 50% water surface ratio, was taken as an example to study the eco-hydraulics techniques for preventing lake eutrophication. Besides external water inflow and outflow, the term related to internal local flow circulation was added in the continuity equation of two-dimensional horizontal hydrodynamic model, and further the hydrodynamic model was calibrated by the scenario of no water exchange. The velocity of 0.2 m/s was suggested to be the critical velocity of controlling algal bloom. To achieve the critical velocity in the whole lake, three factors were analyzed, which are wind, artificial external inflow augmentation and internal local flow disturbance by pump circulation. It is found that the role of wind can be disregarded. For the eco-hydraulics technique of external lake water inflow augmentation, the water flowing route should be firstly optimized, further, the lake inflow has a critical value under specified water level due to the narrow inlets, so the whole lake is difficult to reach the critical velocity to prevent algal bloom, and a combination of external inflow augmentation and internal local flowing disturbance should be considered. Simulation results show that the combination of external water inflow augmentation and internal local flow disturbance requires less eco-flow to achieve the global critical velocity than the sole internal local flow disturbance, for the Ludao Lake, the former requires total eco-flow of 25 m 3/s, which reduces by 50% than the latter requiring total eco-flow of 52 m 3/s.

On the Dynamics of Mangueira Bay—Patos Lagoon (Brazil)

Mangueira Bay is a semi-enclosed system that is very important to the communities living around the city of Rio Grande. It is influenced by multiple and conflicting human impacts. This embayment is connected to Patos Lagoon Estuary through a narrow inlet and its dynamics seem to be related to the dynamics of the estuarine area. This study aims to investigate the mechanisms that control the dynamics of Mangueira Bay under the predominant forcing conditions and evaluate the influence of baroclinic estuarine circulation on the dynamics of the area.The TELEMAC-2D model was used to carry out two- and three-dimensional simulations of Patos Lagoon Estuary. The modeling results indicate that the dynamics of Mangueira Bay are directly related to the dynamics of the main access channel, which are controlled by a combination of remote and local wind effects. A time lag occurs between the excursion of salt in Mangueira Bay and the excursion of salt in the main channel, with salinity penetrating in the embayment when winds from the SW become weaker. Marked horizontal stratification is present throughout the embayment, with salinity gradients changing direction as a function of ebb and flood currents. The area where the embayment connects to the main channel presents higher salinity variability and vertical stratification, while the inner limits are less affected by the dynamics of the channel.

LINKING WATER QUALITY TO LIVING RESOURCES IN A MID‐ATLANTIC LAGOON SYSTEM, USA

The mid‐Atlantic coastal bays are shallow coastal lagoons, separated from the Atlantic Ocean by barrier sand islands with oceanic exchanges restricted to narrow inlets. The relatively poor flushing of these lagoon systems makes them susceptible to eutrophication resulting from anthropogenic nutrient loadings. An intensive water quality and seagrass monitoring program was initiated to track ecological changes in the Maryland and Virginia coastal bays. The purpose of this study was to analyze existing monitoring data to determine status and trends in eutrophication and to determine any associations between water quality and living resources. Analysis of monitoring program data revealed several trends: (1) decadal decreases in nutrient and chlorophyll concentrations, followed by recently increasing trends; (2) decadal increases in seagrass coverage, followed by a recent period of no change; (3) blooms of macroalgae and brown tide microalgae; and (4) exceedance of water quality thresholds: chlorophyll a (15 μg/L), total nitrogen (0.65 mg/L or 46 μmol/L), total phosphorus (0.037 mg/L or 1.2 μmol/L), and dissolved oxygen (5 mg/L) in many areas within the Maryland coastal bays. The water quality thresholds were based on habitat requirements for living resources (seagrass and fish) and used to calculate a water quality index, which was used to compare the bay segments. Strong gradients in water quality were correlated to changes in seagrass coverage between segments. These factors indicate that these coastal bays are in a state of transition, with a suite of metrics indicating degrading conditions. Continued monitoring and intensified management will be required to avert exacerbation of the observed eutrophication trends. Coastal lagoons worldwide are experiencing similar degrading trends due to increasing human pressures, and assessing status and trends relative to biologically relevant thresholds can assist in determining monitoring and management priorities and goals.

Impact of Jetty Construction on the Current and Ecological Systems in an Estuary with a Narrow Inlet

Impact of Jetty Construction on the Current and Ecological Systems in an Estuary with a Narrow Inlet

Long-period Waves and Associated Flows near River Mouth and Narrow Inlet

In order to estimate sediment transport near a river mouth and a narrow inlet, it may be important to investigate the behavior of the long-period waves with periods of several minutes generated by wave groups in the sea. In this study, characteristics of the long-period waves and associated flows near Tenryu river mouth and the inlet of Hamana Lake are discussed based on the field data. Long-period waves are developed almost linearly to both significant wave heights and periods outside the inlet, but they are reduced about half in the inlet. The long-period fluctuation in the flow seems to consist of two components; one is associated with the long-period waves and the other is generated by tidal currents.

Lesson Learnt: Unpredicted Difficult Airway Should Have Been A Predicted One!

We are reporting a case of a 70 year old lady who presented with worsening of dysphagia after having an esophagoscopy a week before as a part of investigations for sub-acute onset of difficulty in swallowing of three to six months duration. She did not have any other past medical history, was not on any regular medications and had no family history of cancer. On examining she had normal heart rate and blood pressure. She was found to have diffuse surgical emphysema extending from the nipples upwards to the neck area. She did not have any difficulty to speak, stridor or shortness of breath. She was diagnosed by computed tomography (CT) to have an iatrogenic perforation of the thoracic segment of esophagus secondary to flexible esophagoscopy. The CT also showed a small collection of fluid around the perforation, but no tumor or any other pathology. Mrs. K was scheduled to have mediastinal drainage and feeding jejunostomy as an emergency procedure, while being further investigated for her initial symptoms of dysphagia. She was assessed for anesthesia. There was history of general anesthesia with grade 1 laryngoscopy 18 months ago for laparoscopic cholecystectomy. On examining the airway, she had a Mallampati class 1 on opening the mouth, thyromental distance was 7 cms, there was good neck movement and no problem with her teeth. All the routine blood tests were normal except a slightly raised white cell count and the ECG was normal. She did not have any apparent risk of difficult airway, and hence a straight forward rapid sequence induction was planned (RSI). On RSI, the laryngoscopy was grade 3 b (unable to lift the epiglottis) even with a McCoy laryngoscope and it was also noted that the epiglottis was red and swollen. But, she was easy to ventilate with the mask. We decided to use the fibreoptic bronchoscope (FOB) which was difficult to negotiate beyond epiglottis due to swollen and firm epiglottis. Our next plan was to insert the Laryngeal mask airway (LMA), and intubate trachea with FOB. LMA was inserted and ventilation through it was easy as well. On introducing the FOB we were happy to note that the epiglottis was lifted, but the view showed severe inflammatory changes of the supraglottic structures including the laryngeal inlet (Fig.1). The trachea was successfully intubated with the 5.5mm endotracheal tube over the FOB after 2 failed tracheal intubation attempts with 6.5mm and 6.0mm endotracheal tubes over the FOB, and the planned procedures were completed. Mrs. K was transferred to intensive care and reviewed by the ENT surgeons who concluded that the mediastinitis secondary to esophageal perforation and tracking of the inflammation was the reason for the swelling and the narrow laryngeal inlet.

The effect of inlet conditions on concentrated suspension flows in abrupt expansions

This work explores the influence of inlet conditions on the particle concentration distribution and flow field of a concentrated suspension undergoing steady flow in an abrupt, axisymmetric 1:4 expansion. Specifically, we consider the impact of inlet conditions in the upstream narrow tube on the resulting downstream profiles. Particle concentration and velocity profiles were measured by using nuclear magnetic resonance imaging. Experiments were conducted with two contrasting inlet tube lengths of 10d1 and 128d1, where d1 is the diameter of the narrow inlet tube. In the short inlet case, none of the particle concentration fields were fully developed upon entering the expansion, whereas several of the suspensions had fully developed profiles in the long inlet case. Results indicate that concentration differences between the core and annular regions were greater for the cases with a long inlet tube than in cases with a short inlet tube, likely owing to the higher degree of particle migration occurring in the long inlet tube before entry into the expansion. Also, the lengths of recirculating regions were greater for suspensions in the long inlet than in the short inlet geometry, while both systems followed the same trend of increasing recirculation length with bulk particle volume fraction and correlation with the ratio of tube center to wall concentration values.

Congenital nasal pyriform aperture stenosis

Congenital nasal pyriform aperture stenosis is an anatomical anomaly which can present as a neonatal airway emergency. The findings of a narrow nasal inlet along with characteristic computerized tomographic findings confirm the diagnosis. This anomaly can occur with other craniofacial syndromes and endocrine disorders which have to be ruled out. The treatment depends on the severity of symptoms with surgery reserved for failure of aggressive medical therapy or severe degrees of nasal narrowing requiring intubation. A sublabial drill-out procedure to widen the pyriform aperture with short duration stenting resolves the problem in a vast majority of patients.

Characteristics of bottom surface sediments in relation to wind and wave action in Lake Kitaura, central Japan

In order to reveal sedimentary processes in shallow lakes, we collected samples from 118 points in Lake Kitaura-a shallow coastal lagoon in the eastern margin of the Kanto region, central Japan, and analyzed grain size distribution, TOC, TN and C/N ratio. We propose a new depositional model for shallow lakes controlled by wave action owing to wind. The distribution of sandy sediments is restricted to areas near the perimeter of the lake, and correlates with areas of low contents of TOC and TN. Alternatively, clay-rich sediments are most widely distributed, and show high concentrations of TOC and TN. The TOC /TN ratio is low, about 7 to 8 throughout the basin, suggesting that major organic matter originated from planktons in the lake. High TOC/TN ratios (over 8) recognized in the northern end of the lake evidently suggests the influence of tributary rivers. The bottom sediments of Lake Kitaura are characterized by a predominance of clayey sediments which cover most of the sublacustrine plain and a narrow zone of sandy sediments along the southern coastal area shallower than 2.5 m. The former sediments are transported as suspended matter reworked from the shallow and shore areas by wave action. The latter are lag deposits sifted by surface drift generated by prevailing wind. Low topography around the lake and small drainage area of each river appears to be the cause of the very small amount or lack of coarse-grained sediments around the river mouths in the narrow inlets. The sandy sediments in the southern margin of the lake are interpreted as relict sediments deposited during the last high sea-level period.

浜名湖における潮汐特性の経年変化に関する研究

Influence of artificial topographic change of an inlet on the tidal response of Hamana Lake is investigated. The lake has a narrow inlet to the ocean that has been stabilized by constructing a pair of jetties before 1980. Although detailed observation of tide had not been carried out since 1980, some reports say that amplitude of tide has become higher recently. In this study, tidal responses were measured at 13 points in HAMANA Lake from October to November in 2003. The present situation of tidal wave propagation was investigated and discussed comparing with the old data.

ベンチマーク筐体内で強制空冷されるPBGAパッケージの熱性能(J01-5 筐体放熱設計,J01 エレクトロニクス実装における熱制御および信頼性評価)

This paper presents the experimental results regarding the thermal performance of a PBGA package model mounted on a printed circuit board in a thin compact casing. The casing exit was linked with an exhaust duct that has an orifice plate for flow rate measurement and an exhaust fan. The effect of the relative position of the PBGA package and a cooling air inlet on the thermal performance was examined. It is confirmed that air flow through a narrow inlet diffuse slightly and that increasing the streamwise distance between the package and the inlet has a limited effect.

Sedimentary photosynthetic pigments of algae and phototrophic bacteria in Lake Hamana, Japan: temporal changes of anoxia in its five basins

We analyzed photosynthetic pigments of algae and bacteria (phototrophic sulfur bacteria: Chromatium and brown Chlorobium) in sediment cores and water samples obtained from five basins of Lake Hamana, a brackish, eutrophic, holomictic lake in Japan, and discussed our findings in relation to the distribution of the phototrophs. The four outer basins are connected to the central basin by narrow inlets. The prevalence of anoxia in Lake Hamana was demonstrated by the widespread presence of bacterial pigments in each core. The construction of training walls in 1954–1956 to direct tidal currents into the lake via Imagire-guchi Channel, the sole inlet for seawater, increased the lake water circulation, suppressed the development of anoxia, and caused Chromatium to disappear. Strong correlations (r2 ≫ 0.7) between total algal carotenoid (TAC) and total bacterial carotenoid (TBC) contents in each core were found in four basins. We ascribe this to the induction of anoxia by water stratification and algal proliferation, which precede the growth of phototrophic sulfur bacteria in the deeper layers of the water column. The slopes of the TBC–TAC correlations in the sediment cores, indicating the extent and stability of anoxia at each site, differed among basins (0.23–0.67) and were inversely related to the exchange rate of water by seawater intrusion in each basin.

Water Balance and Flushing Time in the Restricted Indian River Lagoon (IRL), Florida USA

The water balance calculation in the IRL shows that fresh groundwater discharge is the primary factor, with surface runoff from gaged and ungaged areas as the second freshwater contributor. Precipitation and evaporation are almost in balance fer the entire IRL. Due to high freshwater discharge from ground-water, the annual net flow is outward from the IRL to the continental shelf of the Atlantic Ocean resulting in a relatively short flushing time, denoted as <TEX>$T_{0.5}$</TEX> (50% flushing time) and <TEX>$T_{0.99}$</TEX> (99% flushing time). <TEX>$T_{0.5}$</TEX>, and. <TEX>$T_{0.99}$</TEX> without a tidal effect in the Northern IRL are 17 and 114 days, respectively, during the dry season. During the wet season, they are 10 and 65 days, respectively. Tidal flushing effects are considered in central IRL due to the proximity to Sebastian Inlet. In the Northern Central zone during dry season, <TEX>$T_{0.5}$</TEX>, and. <TEX>$T_{0.99}$</TEX> are 6 and 43 days, respectively and during the wet season 5 and 33 days. In the Southern Central zone they are 2 and 16 days for the dry season,2 and 15 days for the wet season. High groundwater seepage into the IRL is considered to be a positive effect in maintaining relatively good water quality condition even with few narrow inlets.

Interglacial high‐tide coasts in the Bristol Channel and Severn Estuary, southwest Britain: a comparison for the Ipswichian and Holocene

AbstractThe Ipswichian high‐tide coast in the Bristol Channel and Severn Estuary at the time of the highest sea‐levels (5–10 m OD) was wave‐dominated almost everywhere. It is defined by raised beaches and inshore sand shoals, and only in comparatively long but narrow inlets (Somerset Levels) are estuarine conditions evident. The modern Holocene seaway is wave‐dominated at high tide only up to and including the inner Bristol Channel. A muddy upper shore typifies the large, tide‐dominated Severn Estuary to the east and northeast. The larger depth and width of the Ipswichian seaway may explain its greater wave‐dominance, but it is also possible that differences in the sediment regime also contribute to the contrast observed. With water levels continuing to rise, the Holocene seaway could reach Ipswichian depths within a few thousand years and evolve toward greater wave‐dominance. A secondary effect may be the transgression and substantial removal of the Holocene estuarine sequence associated with the Severn Estuary Levels. Copyright © 2002 John Wiley &amp; Sons, Ltd.

The human ductus venosus between 13 and 17 weeks of gestation: histological and morphometric studies

Doppler studies of the ductus venosus are increasingly being integrated in the assessment of fetal well-being. Establishing the precise morphology and structure of the ductus venosus would provide a better understanding of Doppler findings during fetal adaptation. There is conflicting evidence from previous studies about the structure of the ductus venosus, especially with regard to the presence of a sphincter at the ductus venosus inlet. The aim of this study was to examine the morphology and histological structure of the ductus venosus wall and surrounding tissues at 13-17 weeks' gestation. This was a prospective study on 28 fetuses obtained from medical termination of pregnancies between 13 and 17 weeks' gestation. Scanning electron microscopy and histological and immunohistochemical studies were carried out on ductus venosus sections obtained from different spatial planes. The inlet of the ductus venosus contained a shelf which was rich in elastin, but devoid of any evidence of a smooth muscle sphincter. The isthmus of the ductus venosus above the inlet was narrowed, giving the lumen of the vessel an hourglass appearance. The endothelial surface of the ductus venosus, above the level of the inlet, showed longitudinal corrugations along its entire length. Longitudinally arranged elastin fibers were also seen along the length of the ductus venosus. A single layer of longitudinally arranged smooth muscle cells was present along the entire length of the ductus venosus, with occasional individual nerve cells visible in this layer. The presence of an elastin-rich shelf and a narrow ductus venosus inlet orifice may act to accelerate flow from the portal sinus into a high-velocity system in the ductus venosus. The abundant elastin fibers in the adventitia of the ductus venosus may help antegrade wave propagation by elastic recoil. This study clearly demonstrates the lack of an anatomical smooth muscle sphincter at the ductus venosus inlet. However, the combination of endothelial corrugations and innervated smooth muscle support the hypothesis that the ductus venosus is an actively regulated vessel with the capacity to rapidly change diameter along its entire length in response to certain stimuli.

The development of high venous velocity at the fetal umbilical ring during gestational weeks 11-19.

To determine the occurrence of high venous velocities at the umbilical ring in the normal early second trimester, based on the assumption that a narrow umbilical ring may cause obstruction and increased venous blood velocity at the abdominal wall. Cross-sectional study. Hospital antenatal clinic. One hundred and one low risk singleton pregnancies specifically recruited for the study. Ultrasound was used at 11-19 weeks to determine the diameter and velocity in the umbilical vein at the fetal end of the cord and at the inlet through the abdominal wall. Outcome measures 10th, 50th and 90th centiles were estimated for the time-averaged maximum velocity in the cord and at the abdominal inlet. The increase of velocity as the blood entered the abdominal wall was calculated in percent of the velocity in the cord. During weeks 11-12 there was hardly any difference between blood velocity in the umbilical vein at the umbilical ring and that in the cord. From week 13 onwards it was increasingly common to find blood acceleration at the umbilical ring of 50-500%. Velocity increment >50% was found in 0/12 fetuses (0%) at 11-12 weeks, 5/20 (25%) at 13-14 weeks, and in 21/28 (75%) at 17-19 weeks. Blood velocity is higher in the umbilical vein at the abdominal wall than the cord, particularly after 13 weeks of gestation. If acceleration of blood velocity at the umbilical ring is a sign of a narrow inlet, it seems that a progressive tightening occurs during the second trimester.

The development of high venous velocity at the fetal umbilical ring during gestational weeks 11–19

Objective To determine the occurrence of high venous velocities at the umbilical ring in the normal early second trimester, based on the assumption that a narrow umbilical ring may cause obstruction and increased venous blood velocity at the abdominal wall. Design Cross-sectional study. Setting Hospital antenatal clinic. Population One hundred and one low risk singleton pregnancies specifically recruited for the study. Methods Ultrasound was used at 11–19 weeks to determine the diameter and velocity in the umbilical vein at the fetal end of the cord and at the inlet through the abdominal wall. Outcome measures 10th, 50th and 90th centiles were estimated for the time-averaged maximum velocity in the cord and at the abdominal inlet. The increase of velocity as the blood entered the abdominal wall was calculated in percent of the velocity in the cord. Results During weeks 11-12 there was hardly any difference between blood velocity in the umbilical vein at the umbilical ring and that in the cord. From week 13 onwards it was increasingly common to find blood acceleration at the umbilical ring of 50–500%. Velocity increment >50% was found in 0/12 fetuses (0%) at 11–12 weeks, 5/20 (25%) at 13–14 weeks, and in 21/28 (75%) at 17–19 weeks. Conclusions Blood velocity is higher in the umbilical vein at the abdominal wall than the cord, particularly after 13 weeks of gestation. If acceleration of blood velocity at the umbilical ring is a sign of a narrow inlet, it seems that a progressive tightening occurs during the second trimester.

Particle transport through a narrow tidal inlet due to tidal forcing and implications for larval transport

For estuarine‐dependent species, especially those that spawn offshore and whose larvae must reach estuarine nursery areas, advective transport through tidal inlets may be a major factor influencing recruitment variability. We examined the role of tidal forcing on particle transport through a narrow, microtidal inlet along the Texas coast by using a three‐dimensional hydrodynamic and particle transport model. Although tidal forcing is relatively small in the study area, tidal currents through the inlet effectively transport passive particles a distance of about 15 km landward of the inlet. The majority of the particles that enter the inlet are transported to regions that are not suitable for larval settlement. There is limited tidal dispersion of the particles into the bays due to shoreline geometry and bathymetry. Most of the particles that enter the inlet are expelled offshore in the ebb tidal jet resulting in estuarine‐shelf exchange of particles. When acting alone, tidal forcing is not effective at retaining particles in a suitable estuarine habitat, suggesting that other physical or biological mechanisms are required to maintain larvae in an estuarine habitat or that there is substantial along‐shelf transport of larvae.

Characterization and Distribution of Trace Organic Contaminants in Sediment from Masan Bay, Korea. 1. Instrumental Analysis

Masan Bay, located on the southeast coast of Korea, is a long and narrow inlet of a semi-closed bay that receives industrial and municipal wastewaters from the cities of Masan and Changwon. In this study, sediments collected from 28 locations on Masan Bay were analyzed for total organic carbon (TOC), nonylphenol (NP), octylphenol (OP), bisphenol A (BPA), organochlorine pesticides (HCB, HCHs, CHLs, and DDTs), individual polychlorinated biphenyl (PCB) congeners, and 16 polycyclic aromatic hydrocabons (PAHs) to characterize their spatial distribution and contamination status. Concentrations of NP in sediment ranged from 113 to 3890 ng/g on a dry weight basis (dry wt), whereas concentrations of OP and BPA were, on average, 20−110-fold less than those of NP. PAHs were predominated by 4−6-ring compounds with concentrations in the range of 54.1−1100 ng/g dry wt. Concentrations of PCBs in sediment, which were predominated by tetra- and pentachlorobiphenyl congeners, ranged from 10.3 to 148 ng/g, dry wt. Among dif...