Eogenetic Karst Hydrology: Insights From the 2004 Hurricanes, Peninsular Florida

Eogenetic karst lies geographically and temporally close to the depositional environment of limestone in warm marine water at low latitude, in areas marked by midafternoon thunderstorms during a summer rainy season. Spring hydrographs from such an environment in north-central Florida are characterized by smooth, months-long, seasonal maxima. The passage of Hurricanes Frances and Jeanne in September 2004 over three field locations shows how the eogenetic karst of the Upper Floridan Aquifer responds to unequivocal recharge events. Hydrographs at wells in the High Springs area, Rainbow Springs, and at Morris, Briar, and Bat Caves all responded promptly with a similar drawn-out rise to a maximum that extended long into the winter dry season. The timing indicates that the typical hydrograph of eogenetic karst is not the short-term fluctuations of springs in epigenic, telogenetic karst, or the smoothed response to all the summer thunderstorms, but rather the protracted response of the system to rainfall that exceeds a threshold. The similarity of cave and noncave hydrographs indicates distributed autogenic recharge and a free communication between secondary porosity and permeable matrix—both of which differ from the hydrology of epigenic, telogenetic karst. At Briar Cave, drip rates lagged behind the water table rise, suggesting that recharge was delivered by fractures, which control the cave’s morphology. At High Springs, hydrographs at the Santa Fe River and a submerged conduit apparently connected to it show sharp maxima after the storms, unlike the other cave hydrographs. Our interpretation is that the caves, in general, are discontinuous

Sclerotherapy in extrahepatic portal venous obstruction.

One hundred and twenty two patients who presented with variceal bleeding as a result of extrahepatic portal vein obstruction (EHPO) were entered into the sclerotherapy programme with a mean follow up of 23.69 months (range four to 60 months). Eighteen (14.7%) patients were lost to follow up, three (2.4%) patients underwent surgery, and six (4.9%) patients died. Variceal obliteration was achieved in the remaining 95 patients requiring 5.4 (2.4) sessions of sclerotherapy (range 2-18). Seventeen episodes of upper gastrointestinal bleed occurred in 15 patients during sclerotherapy. Recurrence of oesophageal varices was seen in 15 patients. Ten patients developed bulbous gastric varices after obliteration. Major complications including perforation and strictures were seen more commonly in children. Sclerotherapy was associated with a significant reduction in the bleeding rate (bleeds/month/patient) as compared with the presclerotherapy period (p less than 0.001). Endoscopic sclerotherapy is an effective and safe modality in the prevention of variceal bleeds in patients with extrahepatic portal vein obstruction