Using Beryllium-7 as a natural radionuclide for assessing short term soil erosion in arid agricultural land, Egypt.

Abstract

The use of Be-7 as a natural tracer for estimating soil erosion has been demonstrated as a promising tool. Erosion assessment was carried out using Be-7 technique at an arid area of Egypt, located 35 km from Cairo upon a rain event of 54mm. The technique estimates soil erosion and deposition due to rainfall event by comparing Be-7 activity concentration at a reference site and eroded or depositional sites. Soil samples were collected from three fields with different land uses, uncultivated, prickly pear field (Opuntia) and olives field (Olea europaea). The Be-7 in the reference site was observed in the upper 14 mm of soil surface, the reference Be-7 inventory value was 124 +/- 30 Bq.m(-2). Be-7 inventories of the uncultivated field was lower than the reference inventory and ranged from 59.9 to 122.5 +/- 30 Bq.m(-2) . The Be-7 inventories in prickly pear field ranged from 89.5 to 296.6 +/- 30 Bq.m(-2) showing erosion at upslope and deposition downslope in each field, a similar behavior was observed at olives field where Be-7 inventories ranged from 73.9 to 263.6 +/- 30 Bq.m(-2). Net soil erosion rats of 37, 4.1 and 17.9 (t. ha(-1)) were estimated for uncultivated soil, Prickly pear and olives, respectively. Combining these results with visual observations at the three fields reveals that the main driving force of the soil erosion and deposition processes by rain water was the hillslope topography. From the assumptions of applied technique, we can conclude that it gives robust evaluation of soil erosion due to rainfall.