Journal
JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART B-PESTICIDES FOOD CONTAMINANTS AND AGRICULTURAL WASTES
Volume 50, Issue 12, Pages 908-918Publisher
TAYLOR & FRANCIS INC
DOI: 10.1080/03601234.2015.1067101
Keywords
Doxycycline; antibiotic; microbial degradation; photodegradation; hydrolysis; degradation kinetics; speciation; persistence; environmental pollution; zero-order kinetics
Funding
- Research Board of the University of Zimbabwe
- African Network of Chemical Analysis of Pesticides (ANCAP)
- International Program in Chemical Sciences (IPICS)
Ask authors/readers for more resources
The aim of the present work was to establish the kinetics for the degradation of doxycycline in the aquatic environment with a view to arriving at a kinetic model that can be used to predict the persistence of antibiotic with confidence. The degradation of doxycycline in both water and sediment phases of aquatic microcosm experiments, as well as in distilled water control experiments, was studied over a period of 90days. An initial 21% loss due to adsorption by the sediment was observed in the microcosm experiment soon after charging. Biphasic zero-order linear rates of degradation, attributed to microbial degradation of the free and sediment or colloidal particle-adsorbed antibiotic, were observed for both water phase (2.3 x 10(-2) and 4.5 x 10(-3) gg(-1) day(-1)) and sediment phase (7.9 x 10(-3) and 1.5 x 10(-3) gg(-1) day(-1)) of the microcosm experiment. The covered distilled water control experiment exhibited a monophasic zero-order linear rate (1.9 x 10(-3) gg(-1) day(-1)) attributed to hydrolysis, while the distilled water experiment exposed to natural light exhibited biphasic liner rates attributed to a combination of hydrolysis and photolysis (2.9 x 10(-3) gg(-1) day(-1)) and to microbial degradation (9.8 x 10(-3) gg(-1) day(-1)). A kinetic model that takes into account hydrolysis, photolysis, microbial degradation as well as sorption/desorption by colloidal and sediment particles is presented to account for the observed zero-order kinetics. The implications of the observed kinetics on the persistence of doxycycline in the aquatic environment are discussed.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available