| Antibiotics enter the soil through the application of livestock and poultry organic fertilizer,irrigation water,etc.,and will enter the food chain after being absorbed by plants,which may cause passive exposure of human body.Studying the mechanism of plants’absorption and translocation of antibiotics can provide reference for evaluating human health risks.Many antibiotics belong to dissociable organic substances,and they will show different dissociative forms at different p H values,which leads to the complex mechanism of plant absorption and translocation,and the related research is still lacking at present.In this study,celery and wheat were selected as model organisms to study the absorption and translocation of sulfadiazine,sulfamethoxazole,trimethoprim,chloramphenicol,florfenicol,clarithromycin,roxithromycin,enrofloxacin and ofloxacin.The main research contents and results are as follows:（1）Through the study of absorption mechanism,it was found that there were obvious differences in the absorption of different antibiotics in celery and wheat,but the root absorption decreased with the increase of the proportion of neutral form and anion form,and increased with the increase of cation form.The absorption difference between fluoroquinolones and chloramphenicol antibiotics is the most significant,among which the root bioconcentration factors(log BCFroot)of fluoroquinolones is about 2,and the translocation factor（TF）is about 0.0004.The log BCFrootand TF of chloramphenicol are about 0.6 and 0.3,which indicates that there may be different absorption mechanisms between the two antibiotics in celery.Taking chloramphenicol and enrofloxacin as the representatives,the apoplast/symplast experiment showed that the apoplast was major when absorbing chloramphenicol,accounting for 70.1%.When the roots absorb enrofloxacin,symplast was dominated accounting for 82.5%.Through the concentration-dependent experiment,it was found that celery’s absorption of chloramphenicol and enrofloxacin was a carrier-mediated absorption process,but different carriers were involved,which confirmed that there were different mechanisms between celery’s absorption of chloramphenicol and enrofloxacin.The absorption of target antibiotics in wheat is different from that in celery,and different carriers are involved in the absorption of different types of antibiotics.（2）Through the study of transport mechanism,it was found that fluoroquinolones,chloramphenicols,sulfonamides and macrolides were absorbed by the roots of the exposed side of antibiotics and reached the above-ground tissues,but could not be transported down to the roots of the exposed side of nutrient solution.Chloramphenicol,enrofloxacin and ofloxacin may not have a transport mechanism from leaves to stems（or roots）. |
