Migration of antibiotics residual quantities in aquatic ecosystems

The uncontrolled antimicrobial agents use leads to the spread of antibiotic-resistant pathogenic strains. The ingress of antibacterial drugs into surface water through sewage from livestock premises, people's houses, hospitals and during medical and agronomic activities exacerbates this problem. Antimicrobials in surface waters have several ways of developing the process: lethal interaction of antibiotics with hydrobionts, elimination of sensitive taxa and alteration of trophic chains; neutralization of antimicrobials (self-destruction of the molecule, hydrolysis, sorption, abiotic and biotic transformation); non-lethal interaction of antibiotics and hydrobionts with the acquisition of antibiotic resistance signs). There are following indicators proposed to predict the antimicrobial agents impact on the aquatic ecosystem: accumulation factor; the amount of substance per unit mass of plant or animal in one cubic meter of water (mg or mcg per 1m(3)); the maximum amount of a substance that can be contained in an ecosystem without disturbing its basic trophic properties. The basic principles of a dynamic chamber model construction for studying the effect of antibiotics on the ecosystem are based on the following basic statements: 1) the trophic chain is divided into the chambers in which substance is instantaneously mixed in all parts of the chamber in the same way in any direction; 2) the transfer of the substance from one chamber to another occurs according to the laws of first order kinetics, which is described by the system of differential equations. In this case, transition coefficients of a substance between the chambers are constant. It is advisable to use a dynamic chamber model to analyze the migration pathways of substances in a freshwater non-flowing reservoir. For instance, its simplified version consists of the 3 chambers, namely: water - sediments (silt) - biota. It is advisable to use a stationary chamber model for analysing the pathways of antibiotics which enter into the sea with the river flows.