Search

Treated water from wastewater treatment plants that is increasingly used for irrigation may contain pharmaceuticals and, thus, contaminate soils. Therefore, this study focused on the impact of soil conditions on the root uptake of selected pharmaceuticals and their transformation in a chosen soil–plant system. Green pea plants were planted in 3 soils. Plants were initially irrigated with tap water. Next, they were irrigated for 20 days with a solution of either atenolol (ATE), sulfamethoxazole (SUL), carbamazepine (CAR), or all of these three compounds. The concentrations of pharmaceuticals and their metabolites [atenolol acid (AAC), N1-acetyl sulfamethoxazole (N1AS), N4-acetyl sulfamethoxazole (N4AS), carbamazepine 10,11-epoxide (EPC), 10,11-dihydrocarbamazepine (DHC), trans-10,11-dihydro-10,11-dihydroxy carbamazepine (RTC), and oxcarbazepine (OXC)] in soils and plant tissues were evaluated after harvest. The study confirmed high (CAR), moderate (ATE, AAC, SUL), and minor (N4AC) root uptake of the studied compounds by the green pea plants, nonrestricted transfer of the CAR species into the different plant tissues, and a very high efficiency in metabolizing CAR in the stems and leaves. The results showed neither a synergic nor competitive influence of the application of all compounds in the solution on their uptake by plants. The statistical analysis proved the negative relationships between the CAR sorption coefficients and the concentrations of CAR, EPC, and OXC in the roots (R = –0.916, –0.932, and –0.925, respectively) and stems (R = –0.837, –0.844, and –0.847, respectively).

BACKGROUND Lettuce ( Lactuca sativa L.) is a crop that is very sensitive to herbicide contamination owing to its short growing season. The use of long-residual herbicides and non-woven fabric coverings could therefore influence pendimethalin concentrations in soil and lettuce. RESULTS The pendimethalin half-life in soil ranged between 18 and 85 days and was mainly affected by season (i.e. weather), and especially by soil moisture. Pendimethalin degradation in soil was slowest under dry conditions. A longer pendimethalin half-life was observed under the non-woven fabric treatment, but the effect of varying application rate was not significant. Pendimethalin residue concentrations in lettuce heads were significantly influenced by pendimethalin application rate and by non-woven fabric cover, especially at the lettuce's early growth stages. The highest pendimethalin concentration at final harvest was determined in lettuce grown on uncovered plots treated with pendimethalin at an application rate of 1200 g ha−1 (7-38 µg kg−1). Depending on growing season duration and weather conditions, pendimethalin concentrations in lettuce grown under non-woven fabric ranged from 0 to 21 µg kg−1. CONCLUSION Use of transparent non-woven fabric cover with lettuce can help to reduce application rates of soil herbicides and diminish the risk of herbicide contamination in the harvested vegetables. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Pendimethalin [N-(1-ethylpropyl)-3,4-dimethy1-2, 6-dinitrobenzenamine] is a herbicide used worldwide to control most annual grasses and common weeds in cereals, fruit, and vegetables. Its degradation in Haplic Chernozem under controlled greenhouse conditions was studied in this paper. The effect of recommended and doubled pendimethalin doses, as well as the effect of the biopreparate EM-EKO ProBio Plus on pendimethalin degradation in soil and on soil microorganisms was investigated. Pendimethalin half-life ranged from 24.4 to 34.4 days and the double dose did not increase the pendimethalin half-life. Thirty-eight days after pendimethalin application there was no statistical difference between the pendimethalin concentration in soil when applied at the recommended and doubled dose. No effect of pendimethalin on the amount or the activity of soil microorganisms was observed. The effect of EM-EKO ProBio Plus was apparent only on the first sampling of double-dose pendimethalin, however, this bio-preparate had no significant effect on the half-life of pendimethalin, as observed at the end of the experiment. [ABSTRACT FROM AUTHOR]