Influence of habitats and physicochemical factors on trophic transfer processes of antibiotics in a freshwater ecosystem: Application of stable isotopes and human health risks

Habitats of species and physicochemical factors are of great importance in determining the trophic transfer of contam-inants in freshwater ecosystems. There is little information on how multiple physicochemical factors and habitats in-fluence the trophic transfer of antibiotics in freshwater food webs. This study investigated the concentrations of 7 sulfonamides (SAs), 4 fluoroquinolones (FQs), 4 tetracyclines (TCs) and 2 macrolides (MLs) in the Lake Dianshan food web. Stable isotope analysis (SIA), and mathematical models were used to assign trophic levels and distinguish between the benthic food web (BFW) and pelagic food web (PFW). Values of stable nitrogen isotope (delta 15N%o) and sta-ble carbon isotope (delta 13C%o) ranged from 10.2 +/- 0.11 to 19.72 +/- 0.05 and-33.67 +/- 0.18 to-20.79 +/- 0.50, respec-tively. Total concentrations of antibiotics ranged from 36.63 +/- 12.73 ng/g dry weight (dw) to 105.85 +/- 12.95 ng/g dw for all species. The relative abundance of antibiotics was in the following order: 1FQs (36.49 %) > 1SAs (26.70 %), >1MLs (12.63 %) for all biotas. Trophic magnification factor (TMFs) values for individual antibiotics ranged from 0.10 to 1.20 and 0.31 to 1.82 for PFW and BFW, respectively. Three classes of antibiotics 1FQs (p < 0.05), 1TCs (p < 0.05), and n-ary sumation MLs (p < 0.05) showed significant trophic dilution in PFW, opposite to non-significant trophic dilution in BFW. The influence of various physicochemical factors was not strong over trophic transfer (e.g., octanol-water partition coefficient-LogKow (r = -0.05 in PFW, r = -0.14 in BFW) and distribution coefficient-LogD (r = 0.06 in PWF, r = -0.28 in BFW)) except for aqueous solubility (LogS). Results indicated a significantly higher trophic dilution of antibiotics in the PFW than in the BFW. Among the studied six physicochemical factors, only LogS significantly influences (p < 0.05) the trophic transfer of antibiotics in the freshwater food web. Health risk assessments indicated that currently, there were no serious risks present for urban and rural populations.

Automated summary

This study investigates the influence of physicochemical factors and habitats on the trophic transfer of antibiotics in freshwater food webs. The results show significant differences in the transfer of antibiotics in the pelagic and benthic food webs, with higher transfer in the pelagic food web. The study highlights the importance of aqueous solubility as a key factor influencing the trophic transfer of antibiotics.