Antibiotics in rivers also have an urban origin, associated with urban or hospital
wastewater treatment plants (WWTPs). Hospital effluents may contain numerous
compounds, with individual concentrations ranging from a few 100 ng L
À1 up to
47 μg L
À1 (norfloxacin), and specific antibiotics such as vancomycin that are used
exclusively in hospital facilities [70]. These concentrations are very high compared
to those observed in the domestic effluents of residential areas. The mean hospital
effluent concentration was 90-fold higher than that of the domestic effluent. However, since the volumes of hospital effluents are about six times lower than those of
domestic effluents, the mass flow of antibiotics from domestic wastewater was
approximately 1.5 times higher at the inlets of WWTPs [71].
WWTPs therefore play an important role in the life cycle of pharmaceutical
products. Since these molecules are not completely eliminated by WWTPs, urban
effluent outfalls are considered as point sources of antibiotics into the environment
[63]. In WWTPs located in a small catchment in the Seine River basin, the antibiotics more frequently detected in influents were sulfamethoxazole, norfloxacin,
ofloxacin and trimethoprim [71]. These compounds have different behaviours in
WWTPs: fluoroquinolones (norfloxacin and ofloxacin) are mainly eliminated by
adsorption onto sludge. Sulfamethoxazole and trimethoprim are, respectively,
poorly or not adsorbed on particles, and their elimination through sorption is less
efficient [72]. Thus, WWTPs only partly remove antibiotics, and the discharge of
treated water into rivers can lead to increased concentrations downstream of the
discharge, depending on river flow. Dinh et al. [70] observed the occurrence of
fluoroquinolones and sulfonamides (sulfamethoxazole) in water downstream of
WWTP discharge outlet. Fluoroquinolones are gradually adsorbed into the sediments, and only sulfonamides are detected far away from the discharge point.
Therefore, fluoroquinolones accounted for up to 90% of antibiotics in the
sediment [71].
5.3 Antibiotic Contamination in the Seine River
The main antibiotics quantified in the Seine River are sulfonamides, fluoroquinolones, macrolides and diaminopyrimidines [68]. These compounds are used
in human as well as veterinary medicine. For example, sulfamethoxazole is the main
sulfonamide, with concentrations ranging from 6 to 544 ng L
À1 throughout the year.
Their concentrations of sulfonamide increase from upstream to downstream with a
maximum observed downstream of the main WWTP discharge outfalls of the Paris
conurbation (Poissy) (Fig. 5). Besides sulfamethoxazole, fluoroquinolones are the
main family of antibiotics measured in the Seine. Norfloxacin shows the same
pattern as sulfamethoxazole, and ofloxacin is only detected at the farthest downstream site.
Trimethoprim (diaminopyrimidines) is often quantified in the Seine with a background level around 10 ng L
À1 and is mainly present downstream of WWTP
discharges because of its low elimination by WWTPs [72]. The decrease of these
Contaminants of Emerging Concern in the Seine River Basin: Overview of. . .
371
wastewater treatment plants (WWTPs). Hospital effluents may contain numerous
compounds, with individual concentrations ranging from a few 100 ng L
À1 up to
47 μg L
À1 (norfloxacin), and specific antibiotics such as vancomycin that are used
exclusively in hospital facilities [70]. These concentrations are very high compared
to those observed in the domestic effluents of residential areas. The mean hospital
effluent concentration was 90-fold higher than that of the domestic effluent. However, since the volumes of hospital effluents are about six times lower than those of
domestic effluents, the mass flow of antibiotics from domestic wastewater was
approximately 1.5 times higher at the inlets of WWTPs [71].
WWTPs therefore play an important role in the life cycle of pharmaceutical
products. Since these molecules are not completely eliminated by WWTPs, urban
effluent outfalls are considered as point sources of antibiotics into the environment
[63]. In WWTPs located in a small catchment in the Seine River basin, the antibiotics more frequently detected in influents were sulfamethoxazole, norfloxacin,
ofloxacin and trimethoprim [71]. These compounds have different behaviours in
WWTPs: fluoroquinolones (norfloxacin and ofloxacin) are mainly eliminated by
adsorption onto sludge. Sulfamethoxazole and trimethoprim are, respectively,
poorly or not adsorbed on particles, and their elimination through sorption is less
efficient [72]. Thus, WWTPs only partly remove antibiotics, and the discharge of
treated water into rivers can lead to increased concentrations downstream of the
discharge, depending on river flow. Dinh et al. [70] observed the occurrence of
fluoroquinolones and sulfonamides (sulfamethoxazole) in water downstream of
WWTP discharge outlet. Fluoroquinolones are gradually adsorbed into the sediments, and only sulfonamides are detected far away from the discharge point.
Therefore, fluoroquinolones accounted for up to 90% of antibiotics in the
sediment [71].
5.3 Antibiotic Contamination in the Seine River
The main antibiotics quantified in the Seine River are sulfonamides, fluoroquinolones, macrolides and diaminopyrimidines [68]. These compounds are used
in human as well as veterinary medicine. For example, sulfamethoxazole is the main
sulfonamide, with concentrations ranging from 6 to 544 ng L
À1 throughout the year.
Their concentrations of sulfonamide increase from upstream to downstream with a
maximum observed downstream of the main WWTP discharge outfalls of the Paris
conurbation (Poissy) (Fig. 5). Besides sulfamethoxazole, fluoroquinolones are the
main family of antibiotics measured in the Seine. Norfloxacin shows the same
pattern as sulfamethoxazole, and ofloxacin is only detected at the farthest downstream site.
Trimethoprim (diaminopyrimidines) is often quantified in the Seine with a background level around 10 ng L
À1 and is mainly present downstream of WWTP
discharges because of its low elimination by WWTPs [72]. The decrease of these
Contaminants of Emerging Concern in the Seine River Basin: Overview of. . .
371