War-induced soil disturbances in north-eastern Ukraine (Kharkiv region): Physical disturbances, soil contamination and land use change.

The war in Ukraine is having a dramatic impact on the physical, chemical and biological soil properties. A comprehensive study of the war-affected soils during the ongoing war is a challenging task owing to the many constrains that arise during fieldworks. Remote sensing data is the best solution for overall analysis of physical soil disturbances. With the advancement in the very-high spatial resolution satellite imagery, it has become feasible to identify precise indicators of the war-induced physical soil disturbances. Here, we present a comprehensive methodology for assessing the war-affected soils tested in the Kharkiv region (north-eastern Ukraine). The methodology combines analysis of remote sensing data, soil mapping and subsequent soil modelling, field research and laboratory measurements. High-resolution satellite images, which acquired via WorldView and GeoEye, have enabled the identification of 420,615 craters and 3411 ha of soils, which impacted by the movement of heavy military vehicles. Soil bombturbation covers 4212 ha and is represented by entire or partial soil mixing, as well as the soil burial under the ejected material. The research showed that craters become the sites of secondary geomorphic processes that lead to crater filling and degradation of the surrounded areas. Furthermore, all sampled craters showed enrichment in heavy metals, especially cadmium, copper, lead and zinc. However, their concentration is predominantly only 1.1-1.5 times more than background value and almost does not exceed threshold limit values in Ukraine. Conversely, the sites of military helicopter crash and 'fresh' missile falling site are displayed critical contamination with heavy metals. The paper also discusses the feasibility of combining data from soil physical disturbances with land use change in order to assess the risk of landmines and the presence of unexploded ordnance, environmental effect of which is remain unclear in Ukraine.