Resolving the thickness of peat deposits with contact-less electromagnetic methods: A case study in the Venice coastland

Peat soils are typical deposits characterizing wetlands and reclaimed farmlands. They are important carbon reservoirs and when degraded (e.g., erosive processes, fires, draining and plowing) massive carbon dioxide volumes are released. This leads to increase greenhouse effect and induce serious land subsidence. Thus, mapping the volume of peat deposits is crucial in order to estimate the carbon mass and the potential release of carbon dioxide and consequent loss in soil elevation. Despite the importance of such estimations, forecasting and quantifying the peat thickness is still a challenge. Direct sediment coring provides local information that is difficult to extend to large territories. Indirect geophysical methods are unable to resolve lithological contrasts in the presence of saltwater contamination in coastal areas. In this work, we show the results obtained using two contact-less electromagnetic methods for the characterization of peat deposits in a peatland site of the Venice coastland, Italy. Specifically, a multi-frequency portable instrument (FDEM) and an airborne time-domain electromagnetic one (AEM), known for their very high and relatively low vertical resolution respectively, were used to collect data over a former wetland then reclaimed for agricultural purposes. Additional electrical resistivity tomography (ERT) data are used together with sediment core data to assess the effectiveness and accuracy of the contact-less methods. Results show that both FDEM and AEM are very effective in detecting the presence of the peat layer, despite its low thickness (<2 m) and the high electro-conductive subsoil because of saltwater contamination. However, the AEM method overestimated the peat thickness while the FDEM could accurately resolve the peat thickness even where the layer was thinner than 1 m. When compared to the electrical features extracted from the ERT, discrepancies are on average lower than 30%; when compared to the borehole data, discrepancies are on average slightly higher than 6%.

[Ultrasonic videolaparoscopic cholecystectomy: evolution of a revolutionary technique]

AIM

The present retrospective study, which lasted about six months from the beginning of March to the end of August 2008, involved 60 patients suffering from symptomatic calculosis of the gall bladder.

METHODS

The patients were operated on with laparoscopy: 30 with traditional instruments, 30 using ultrasound multifunctional scissors.

RESULTS

The numerous advantages for the patient and surgeon are immediately evident; in addition, from the economic viewpoint the procedure is advantageous compared to the traditional method because single-use material is employed exclusively. We found less tissue trauma and a lower incidence of short-term complications, such as reoperation for faulty closure of the cystic duct and the cystic artery. It was never necessary to use permanent haemostatic clips. The use of a single instrument for gripping, sectioning and closing haematic and biliary vessels permitted faster, safer and more accurate surgery in the absence of any production of smoke.

CONCLUSIONS

In lithiasic pathology of the gall bladder, videolaparoscopy for cholecystectomy is presently considered the operation of first choice. The technique enables the surgeon to respect to the utmost the patient's physical and mental integrity. As the third millennium dawns, technological innovation is able to bring a significant improvement to this procedure. The ultrasound dissector Ultracision is symbolic of development and constant progress.

A rare case of pancreatic lipoma

During CT scanning, a pancreatic lipoma was diagnosed in a 70 year-old woman presenting with abdominal pain, elevated amylase and abnormal liver function tests. The patient underwent surgical excision of the lipoma located in the head of the pancreas. The postoperative course was uneventful. This is the third case of pancreatic lipoma described in the literature. It is a very rare neoplasm that should be included in the category of "non-ductal" tumors of the pancreas. The role of different diagnostic tools for the differential diagnosis of ductal pancreatic adenocarcinoma is discussed.