Residual and migration characteristics of norfloxacin in two mangrove ecosystems

Abstract

Direct discharge of aquaculture wastewater in coastal areas could increase concentrations of antibiotics in coastal mangrove forests. This study focused on the Gaoqiao Mangrove Nature Reserve in Zhanjiang City, Guangdong Province. Norfloxacin (NOR) residues in rhizosphere sediments, plant roots, branches, and leaves of two dominant mangrove communities, Rhizophora stylosa and Avicennia marina, the correlation between physical properties of rhizosphere deposition and residual NOR in sediments, and NOR accumulation in the root system were analyzed. Significant differences were noted in NOR residues in rhizosphere sediments of R. stylosa and A. marina, with higher NOR concentrations than those in other wetland sediments locally and abroad. NOR accumulation in R. stylosa was higher in the branches than in the roots and was also significantly higher than that in A. marina. Thus, both species could accumulate NOR from the environment with R. stylosa showing a stronger potential to purify the environment. Cation exchange capacity and total organic carbon could affect NOR distribution in the rhizosphere sediment, and total organic carbon content could reduce NOR uptake by mangrove roots. This study contributes to research on the migration and adsorption characteristics of antibiotics in mangrove wetlands.