Phytoremediation of pesticide- and mineral oil-contaminated soils with perennial grasses in Ukraine

The most frequent contaminants of soil in Europe are heavy metals and mineral oil [1]. There are more than 5000 pesticide-contaminated in Ukraine that require cleanup [2]. In Ukraine before Russian invasion, according to the State Service of Ukraine for Geodesy, Cartography and Cadastre (StateGeoCadastre) there were around 125.44 thousand hectares of lands, contaminated by industrial and other waste as of January 1, 2019 [3]. Areas contaminated with explosives and mineral oil as a result of military activities after Russian invasion are under assessment, but can amount at least 5 million hectares of agricultural lands [4].Phytoremediation with perennial grasses can be a solution to large areas of contaminated lands in Ukraine, as it can be used to extract heavy metals and speed up degradation of organic contaminants [5].During 2021-2023, field trials performing phytoremediation approach were conducted at two contaminated sites in Ukraine within CERESiS (ContaminatEd land Remediation through Energy crops for Soil improvement to liquid biofuels Strategies) H2020 Project (GA 101006717). First site with fuel and mineral oil contamination and the second - with pesticides contamination, located in the north-western region of Ukraine. Pesticide contamination of the site occurred through minor leaks as a result of a long-term use of pesticides warehouse. Contamination with the fuel oil occurred through small leaks as a result of over 40 years of use and storage of fuel and lubricants by refuelling agricultural machinery. Both contaminated sites represent historical contamination as neither pesticides, nor fuel have been used or stored on the farm for more than 10 years. Baseline soil characterization showed that sites had significant chromium contamination, as well as high quantities of antimony, cadmium, hexachlorocyclohexane and petroleum products.For phytoremediation, trial sites were planted with Miscanthus x giganteous and Phalaris arundinacea. Both plants showed good performance, but Phalaris presented strong dependency on water availability. The second year harvest showed Miscanthus yield around 20 t of dry matter per hectare, and Phalaris more than 5 t of dry matter per hectare at both contaminated sites. Soil characterization after 2 years of growing showed promising phytoremediation potential of both crops with Miscanthus showing better results with decontamination from HCH, Chromium, Cadmium, Antimony and Stanum, and Phalaris performing more efficiently regarding decontamination from petroleum products and phenols.[1] Pérez & Eugenio (2018).[2] Moklyachuk et al. (2010).[3] Information of State Service of Ukraine for Geodesy, Cartography and Cadastre №6-28-0.21-4979.2-19 from 07.06.2019.[4] https://www.pravda.com.ua/eng/news/2023/03/3/7391820/[5] https://www.bbc.com/future/article/20230221-the-toxic-legacy-of-the-ukraine-war