Erosion Levels in Santander Bay Estuary (Spain)

Full Text: Soil erosion was evaluated in several points from the Santander bay proximity in the north of Spain. The used method is based on the measurement of the radioactive isotope Cs-137 present in the soil. The rates and spatial extent of Cs-137 loss can be established and thus soil movement budgets are easily estimated. Core samples were collected in 18 points and sectioned at 5 cm depth intervals. Samples of soil were air dried and passed through a 2 mm sieve. Radionuclide activities were measured using a high resolution, low background, Ge HP gamma ray detector. This soil movements are estimated by comparing the activity of Cs-137 of a soil point with the activity of Cs-137 in sites assumed to be un eroded. The obtained results show high and regular soil erosion levels for the most part of studied estuary. The last can be explained by the intensive building construction taken place in the area in the last few years. On the other hand, the Ra-226, Th-232 and K-40 concentration levels in soil allow the correlation with its concentration levels in bay sediments, to establish a transport scheme of the eroded material