Fate of the veterinary antibiotic¹⁴C-difloxacin in soil including simultaneous amendment of pig manure with the focus on non-extractable residues

Structural and functional response of the soil bacterial community to application of manure from difloxacin-treated pigs

“…Recently, in the field experiment reported here and in other trials, it was shown that DIF was hardly (bio) accessible and rapidly formed nonextractable residues, which might limit its effect on the microbial community (Rosendahl et al ., ). In another experiment, 14 C‐labeled DIF was applied with manure or water to soil, and the mineralization of 14 C‐DIF was shown to be low (below 0.2%), while nonextractable residues of 14 C‐DIF increased to 70–74% after 56 and 120 days (Junge et al ., ). Nevertheless, in a microcosm experiment, effects of DIF on the microbial biomass, respiration, potential denitrification, and ratio of bacteria/fungi were observed up to eight days after application by manure (Kotzerke et al ., ).…”

Metabolic fate of the14C-labeled herbicide clodinafop-propargyl in a sediment–water system

“…[17,21,22] For that purpose, the fulvic acid solution obtained after precipitation of the humic acids (about 130 mL; see before) was laid on an XAD-7 column (length: 20 cm, diameter: 2 cm; Merck, Darmstadt, Germany). The column was washed with 12 mL of water, and fulvic acids were eluted successively with 20 mL of 0.1M NaOH and 60 mL of water.…”

“…Microbial activity (dimethylsulfoxide reduction) was determined according to a published procedure. [17][18][19][20] Five 1 g air dried aliquots of each sediment assay (parallels and control) were utilized for the test.…”

“…After collection and removal of larger particles, the sediment was sieved (mesh width: 2 mm), mixed, and stored prior to use at 4 C. The water sample was filtrated through a 0.45 mm cellulose membrane. The main physicochemical properties of the sediment were determined according to methods described previously; [16,17] sand: 16.78%, silt: 72.23%, clay: 10.83%, total C org : 3.62% (w/w), total C inorg : 1.72% (w/ w), total C: 5.34% (w/w), loss by combustion of the dried (100 C, 4 h) sediment: 9.35%.…”

“…In case of veterinary pharmaceuticals difloxacin and sulfadiazin, both, the respective free parent and 14 C firmly associated with fulvic acids were observed. [17,31] When 14 C-labeled simazine was incubated with biowaste (compost), HPSEC demonstrated that the dissolved organic matter isolated from the aqueous leachate contained both free simazine and radioactivity supposedly covalently bound to humic materials. [32] It is worth mentioning that in the last two decades, the supramolecular structure of humic substances including HPSEC procedures of isolated fractions has been discussed controversially (polymers vs. associations of small molecules).…”