108 Oral Presentations Investigations of the medium scaled spatial distribution of

Radiocaesium ground deposition is caused by fallout from atmospheric nuclear weapon tests and from nuclear power plant acci-dents like in Chernobyl in 1986 (De Cort 1998). Especially in forest ecosystems this nuclide is easily introduced into the food chain. Although radiocaesium concentration in many forest-dwelling species tend to decrease 18 years after the Chernobyl nuclear accident, radioactive contamination of wild boar keeps unchanged in many contaminated forested areas of Germany. In Rhineland-Palatinate, radiocaesium contamination of wild boar meat (venison) is found mainly in the Palatinate Forest (Landesuntersuchungsamt Rheinland-Pfalz 2002). Considering the location of sampling in this area, we found that occurrence of contaminated wild boar was restricted to the western parts (Anonymus 2003, Hohmann & Huckschlag 2004a, Fig. 1). It is assumed that this east-west gradient of wild boar contamination in the area is based on an east-west-gradient of the radiocae-sium fallout, following the Chernobyl accident. In order to test this hypothesis surface radiocaesium activity was measured in-situ gammaspectrometrically in the year 2004. A measurement vehicle of the Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht (Mainz) with a portable hyper-pure germanium (HPGe) coaxial detector (p-type; measured efficiency: 10 %; Detector Systems GmbH, Mainz) and a multi-channel analyser was used. First the relaxation length of the radiocaesium was found out in a pilot study (Anonymus 2004a). Measurements were taken along three east-west transects in the north, centre, and south of the Palatinate Forest. Each transec