[Behavior of benzo(a)pyrene in the soil and passage from soil to crops]

The behaviour of Benzo[a]pyren (BaP) in the soil and its passage from the soil into the crops has been investigated by means of model tests. In situ fluorescence spectroscopy enables a detection of 0.01 micrograms/BaP/kg with recoveries ranged from 75 to 99.6% and an average variation coefficient of 15%. A decomposition of BaP in test soils within 18 months from 30 mg/kg to 1.5 mg/kg could be attributed to decomposition by soil bacteria. After addition of bactericidal substances to the soil there was no decomposition for several years. In soils with concentrations below 1000 micrograms BaP/kg no passage of BaP into the crops can be detected. Contrary to the opinion of several authors that BaP does not pass from the soil into the crops, model tests conducted for a few years show that a relevant passage into crops such as carrots and radish, as well as into lettuce, spinach and parsley, is possible. The passage into potatoes, tomatoes, peas, and beans is less significant. The degree of contamination of crops is in a certain relation to the degree of the contamination of the soils, but this has only been found with a BaP content of more than 1000 micrograms/kg. Sandy soils which significantly exceed the BaP content of about 1000 micrograms/kg, as they may occur in industrial areas, above all near emittents, are not suitable for the cultivation of some vegetables, such as lettuce and carrots, for human nutrition.