Ondřej Jakšík

An analysis of the dissipation of pharmaceuticals under thirteen different soil conditions.

The presence of human and veterinary pharmaceuticals in the environment is recognized as a potential threat. Pharmaceuticals have the potential to contaminate soils and consequently surface and groundwater. Knowledge of contaminant behavior (e.g., sorption onto soil particles and degradation) is essential when assessing contaminant migration in the soil and groundwater environment. We evaluated the dissipation half-lives of 7 pharmaceuticals in 13 soils. The data were evaluated relative to the soil properties and the Freundlich sorption coefficients reported in our previous study. Of the tested pharmaceuticals, carbamazepine had the greatest persistence (which was mostly stable), followed by clarithromycin, trimethoprim, metoprolol, clindamycin, sulfamethoxazole and atenolol. Pharmaceutical persistence in soils was mostly dependent on the soil-type conditions. In general, lower average dissipation half-lives and variability (i.e., trimethoprim, sulfamethoxazole, clindamycin, metoprolol and atenolol) were found in soils of better quality (well-developed structure, high nutrition content etc.), and thus, probably better microbial conditions (i.e., Chernozems), than in lower quality soil (Cambisols). The impact of the compound sorption affinity onto soil particles on their dissipation rate was mostly negligible. Although there was a positive correlation between compound dissipation half-life and Freundlich sorption coefficient for clindamycin (R=0.604, p<0.05) and sulfamethoxazole (R=0.822, p<0.01), the half-life of sulfamethoxazole also decreased under better soil-type conditions. Based on the calculated dissipation and sorption data, carbamazepine would be expected to have the greatest potential to migrate in the soil water environment, followed by sulfamethoxazole, trimethoprim and metoprolol. The transport of clindamycin, clarithromycin and atenolol through the vadose zone seems less probable.

Simultaneous sorption of four ionizable pharmaceuticals in different horizons of three soil types

Soils may be contaminated by human or veterinary pharmaceuticals. Their behaviour in soil environment is largely controlled by sorption of different compounds in a soil solution onto soil constituents. Here we studied the sorption affinities of 4 pharmaceuticals (atenolol, trimethoprim, carbamazepine and sulfamethoxazole) applied in solute mixtures to soils taken from different horizons of 3 soil types (Greyic Phaeozem on loess, Haplic Luvisol on loess and Haplic Cambisol on gneiss). In the case of the carbamazepine (neutral form) and sulfamethoxazole (partly negatively charged and neutral), sorption affinity of compounds decreased with soil depth, i.e. decreased with soil organic matter content. On the other hand, in the case of atenolol (positively charged) and trimethoprim (partly positively charged and neutral) compound sorption affinity was not depth dependent. Compound sorption affinities in the four-solute systems were compared with those experimentally assessed in topsoils, and were estimated using the pedotransfer rules proposed in our previous study for single-solute systems. While sorption affinities of trimethoprim and carbamazepine in topsoils decreased slightly, sorption affinity of sulfamethoxazole increased. Decreases in sorption of the two compounds could be attributed to their competition between each other and competition with atenolol. Differences between carbamazepine and atenolol behaviour in the one- and four-solute systems could also be explained by the slightly different soil properties in this and our previous study. A great increase of sulfamethoxazole sorption in the Greyic Phaeozem and Haplic Luvisol was observed, which was attributed to elimination of repulsion between negatively charged molecules and particle surfaces due to cation sorption (atenolol and trimethoprim) on soil particles. Thus, our results proved not only an antagonistic but also a synergic affect of differently charged organic molecules on their sorption to soil constituents.

Using magnetic susceptibility mapping for assessing soil degradation due to water erosion.

Jaksik O., Kodesova R., Kapicka A., Klement A., Fer M., Nikodem A. (2016): Using magnetic susceptibility mapping for assessing soil degradation due to water erosion. Soil & Water Res., 11: 105–113. This study focused on developing a method for estimating topsoil organic carbon content from measured massspecific magnetic susceptibility in Chernozems heavily affected by water erosion. The study was performed on a 100 ha area, whereby 202 soil samples were taken. A set of soil samples was divided into 3 subsets: A (32 samples), B (67 samples), and C (103 samples). The mass-specific magnetic susceptibility using low ( χ lf ) and high ( χ hf ) frequency, and organic carbon content were measured at all soil samples. The contents of iron and manganese, extracted with a dithionite-citrate solution (Fe d , Mn d ) and ammonium oxalate (Fe o , Mn o ), were quantified in A and B samples. Models for predicting organic carbon content from magnetic susceptibilities were designed as follows: (1) subset A was used as the training set for calibration, and subsets B and C were used as the test sets for model validation, either separately (subset B only), or together (merged subsets B and C); (2) merged subsets A and B were used as the training set and subset C was used as the test set. Results showed very close correlations between organic carbon content and all measured soil properties. Obtained models relating organic carbon content to mass-specific magnetic susceptibility successfully predicted soil organic carbon contents.

The impact of the permanent grass cover or conventional tillage on hydraulic properties of Haplic Cambisol developed on paragneiss substrate

Abstract This study is focused on the comparison of soil structure and soil hydraulic properties of a Haplic Cambisol on paragneiss under two different land managements. Soil samples were taken from all diagnostic horizons (A, Bw and C) of the soil profile under the permanent grass cover (grassland) and under the conventional tillage (arable land). Basic soil properties were measured. Aggregate stability was assessed using the WSA index. Soil composition was evaluated using micromorphological images. Tension disk infiltrometers with two diameters of 2.22 and 10.25 cm (and applied pressure head of −2 cm) and Guelph permeameter were used to measure unsaturated and saturated hydraulic conductivities, respectively. Soil hydraulic properties were measured in the laboratory using the multistep outflow experiment, which was performed on the undisturbed 100 cm3 soil samples. Results showed that the unsaturated and saturated hydraulic conductivities measured in all horizons were lower at the arable land than conductivities at the grassland. The shapes of the soil water retention curves for A and Bw horizons were also different, indicating that soil below the grass contained larger fraction of the large capillary pores, which also corresponded to measured hydraulic conductivities and soil structure characteristics. Differences between both locations were caused by a negative impact of tillage (inflicting soil degradation) and positive influence of grass (increasing organic matter content and improving soil aggregation).