XENOBIOTIC ORGANIC-SUBSTANCES CONTENT IN CROPS IRRIGATED WITH WATER FROM THE LABE RIVER

Vegetation pot trials were carried out with savoy cabbage and carrot, irrigated with water of the Labe river from the sampling profile Valy and, alternatively, with well water contaminated artificially by addit ion of Delor 106, DDT, benzo-a-pyrene, fluoranthene, 1,2-dichloroethan e, p-dichlorobenzene, o-dichlorobenzene and naphthalene. Concentration s of the xenobiotic organic substances (XOS = XOL) in irrigation water were adjusted to 0.5, 1, 10, 100, 1000 and 10 000 mug.litre-1 (concen trations of all XOL were the same). The plants grown in the pots were tested for their mutagenic action. It becomes obvious from Tab. I that the Labe water from the profile at Valy contained mostly dichlorobenz enes and 1,2-dichloroethane (up to several tens of mug.litre-1) while its content of benzo-a-pyrene and DDT was at minimum (below the detect ion limit in all cases). High PCBs concentrations were also found in s ome samples of the Labe water. Namely, in three of the total of nine s amples were the PCBs concentrations (0.087, 0.061 and 0.056 mug.litre- 1) higher than the maximum admissible concentration (0.050 mug.litre-1 ) which is required for irrigation water of the first class of purity by the irrigation water quality standard CSN 75 7143. In most cases, t he contents of XOL in the plants which were irrigated with the Labe wa ter from the profile at Valy does not differ substantially from the XO L contents in the plants irrigated with the reference water (Tab. III) . The increased content of DDT in carrot (by 91 mug.kg-1, compared wit h the variant irrigated with the reference water) cannot be attributed to the irrigation water, as the input of DDT into soil contributed by the Labe water was the same as that introduced with the reference wat er (Tab. II). In the heads of the savoy cabbage, the maximum amounts o f 1,2-dichloroethane were found, while the roots of carrot accumulated the most of DDT. DDT is also the XOL whose concentrations are most di fferent when the heads of savoy cabbage are compared with the roots of carrot irrigated with the same Labe water. Similarly, in the variants irrigated with water artificially contaminated by XOL, the contents o f DDT were much higher in carrot than in savoy cabbage (Tab. IV). The trials in which the artificially contaminated water was used showed th at the contents of XOL in plants do not increase proportionally to die increasing input of these substances with irrigation water. The conce ntrations of naphthalene were surprisingly at their highest levels, bo th in savoy cabbage and in carrot, in variants with the lowest level o f irrigation water contamination. The concentrations of other XOL in s avoy cabbage and carrot did not increase significantly, compared to th e variants irrigated with reference water, until the inputs of XOL wer e much higher than those supplied with the Labe water, typically by se veral orders of magnitude (except for 1,2-dichloroethane); this is evi dent when comparing Tabs II and IV. Neither the Labe water from the pr ofile at Valy, nor the water contaminated artificially with XOL, when used for irrigation, exhibited any influence upon the mutagenic action of savoy cabbage and carrot. A similar result had been obtained previ ously from the testing of the mutagenic action of a number of other cr ops (early potatoes, kohlrabies, early cabbage, cauliflower, carrot, s ugar beet and apples) grown in the field and irrigated with Labe water (Zavadil 1992, 1993). A probable conclusion can be drawn based on the results that the plants irrigated with the Labe water do not produce stable metabolites with mutagenic action from XOL present in irrigatio n water.