Channel sedimentation within the urbanized river Tame,U.K.

This study examines the distribution and composition of fine sediment within the gravel-bed substrate of the channelized River Tame, within and below the Birmingham conurbation, United Kingdom. A freeze coring technique was employed to collect undistributed volumetric samples, to a depth of 30-40 cm, providing information not only on the gross deposit but also on the vertical structure of the river bed in terms of textural and geochemical properties. The urbanized substrate differs from that of the natural river, both in terms of the volume of matrix sediment present, which is less than ?expected’?, and in the size characteristics of the coarse framework and finer matrix components. Moreover heavy metal concentrations within the urbanized matrix sediment are up to 3000 times greater than background levels and maximum concentrations are shown to occur at a depth of more than 15 cm within the substrate.     

Orbital mass in a child causing somnolence, nausea and bradycardia

Aorto-esophageal fistula due to ruptured thoracic aortic aneurysm is very rare but is associated with extremely high mortality. An 81-year-old woman was admitted due to repeated hematemesis. Endoscopic examination revealed ulceration with blood clot on the mid-esophagus and compression of an extra-esophageal mass. The thoracic CT scan revealed an aorto-esophageal fistula due to a ruptured descending thoracic aortic aneurysm. Surgery was performed on April 3, 1996. We report an aorto-esophageal fistula managed successfully in one stage by resection and replacement of the aortic aneurysm with a prosthetic graft and total esophageal resection. The esophagus was reconstructed using orthotopic gastric interposition with omentopexy around the prosthetic aortic graft. The postoperative course was uneventful and there have been no signs of mediastinal sepsis, graft infection or pyothorax 12 months postoperatively. We suggest that the resection of both the aneurysm and the esophagus as well as the immediate reconstruction of the esophagus by orthotopic gastric interposition to obliterate the retrosternal space are important technique in the management of intrathoracic infections.     

Effects of daily precipitation and evapotranspiration patterns on flow and VOC transport to groundwater along a watershed flow path

MTBE and other volatile organic compounds (VOCs) are widely observed in shallow groundwater in the United States, especially in urban areas. Previous studies suggest that the atmosphere and/or nonpoint surficial sources could be responsible for some of those VOCs, especially in areas where there is net recharge to groundwater. However, in semiarid locations where annual potential evapotranspiration can exceed annual precipitation, VOC detections in groundwater can be frequent. VOC transport to groundwater under net discharge conditions has not previously been examined. A numerical model is used here to demonstrate that daily precipitation and evapotranspiration (ET) patterns can have a significant effect on recharge to groundwater, watertable elevations, and VOC transport. Ten-year precipitation/ET scenarios from six sites in the United States are examined using both actual daily observed values and "average" pulsed precipitation. MTBE and tetrachloroethylene transport, including gas-phase diffusion, are considered. The effects of the precipitation/ET scenarios on net recharge and groundwater flow are significant and complicated, especially under low-precipitation conditions when pulsed precipitation can significantly underestimate transport to groundwater. In addition to precipitation and evapotranspiration effects, location of VOC entry into the subsurface within the watershed is important for transport in groundwater. This is caused by groundwater hydraulics at the watershed scale as well as variations in ET within the watershed. The model results indicate that it is important to consider both daily precipitation/ET patterns and location within the watershed in order to interpret VOC occurrence in groundwater, especially in low-precipitation settings.