Effects Of Antibiotics On Soil Biochemical Characterisation

The objective is to understand the effects of antibiotics on soil biochemical processes and nitrifiers. Three soils were amended with streptomycin, chloramphenicol and penicillin at two concentrations,1 mg·g-1 and 10 mg·g-1 respectively, then the soils were incubated at 25℃before biochemical analyses. Several indicators, e.g, soil respiration, nitrification, ammonia oxidizing archaea and bacteria, were used to evaluate the effects of antibiotics on soil ecological characterization. The results are as follows:1. Streptomycin, chloramphenicol and penicillin can inhibit the color reaction of ammonium with sodium chlorate and phenol. Similarly, the antibiotics above can also inhibit the color reaction of ammonium with salicylic acid. Therefore, conventional artificial colorimentry is not suitable for ammonium measuring in extract containing.2. The three antibiotics can be degraded in soils, and the order of degradation rate was as follows:penicillin>streptomycin>chloramphenicol. Degradation potential of antibiotics in different soils were significantly different, and the vegetable soil had higher degradation potential than tea orchard soil and paddy soil.3. The ammonium concentration increased with antibiotics amendment. The results suggested that the antibiotics were not a limiting factor for soil mineralization. The degradation of antibiotics resulted in the increase of ammonium concentration and the order of the degradation rate is penicillin>streptomycin>chloramphenicol.4. The nitrate concentration decreased although the degradation of antibiotics increased soil ammonium concentration, which suggested that nitrification was significantly inhibited by antibiotics. The dynamics of nitrate concentration reflected the combined positive and negative effects. The combined effects include the stimulation of ammonium which was from antibiotics degradation and the inhibition of antibiotics on nitrification.5. The effect of antibiotic on ammonia oxidizers (AOA and AOB) was determined by soil type. The resistance to antibiotics of ammonium oxidizer community in the vegetable soil was higher than in the tea orchard soil and paddy soil.