Occurrence and distribution of antibiotics in sediments from black-odor ditches in urban areas from China.

Antibiotic levels in black-odor water could reflect the usage amount of antibiotics in population. On the other hand, these antibiotics are the source of antibiotics in the environmental water. Currently, researches on antibiotics in black-odor sediments are still lacking. In this study, 174 black and odor sediment samples from 74 cities in 28 provinces in China were collected for analysis. Among 44 targeted antibiotics, 13 antibiotics were detected in more than 30% of sediment samples. Fluoroquinolones and tetracyclines were the predominant antibiotics in these field samples, with average concentrations of up to 2074 and 1902 ng/g dry weight (dw), respectively, followed by macrolides (87.9 ng/g dw), lincosamides (8.06 ng/g dw) and sulfonamides (8.38 ng/g dw). High antibiotic contamination levels were almost always detected in black-odor sludges from economically less developed small cities; however, the difference in antibiotic concentrations between well-developed and small cities in China was not statistically significant. In addition, among the seven regions within China, no significant difference in concentrations was observed for the most antibiotics. Variances in antibiotic composition patterns in the 28 provinces of China may be due to differences in bacterial resistance, prescription habits, efficacy, and sediment carbon concentrations among various regions. There were significant positive correlations among some antibiotics in the same or different classes.