3 Natural Attenuation of Pharmaceuticals in the Aquatic …
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and functional groups. None of the physicochemical and molecular properties considered correlated with the mean values of v f . The v f values of some pharmaceuticals
were similar among the various study sites. However, for other pharmaceuticals, significant variability was obtained amongst sites. This may be attributed to varying
log K ow values. When hydrophobic compounds sorb onto suspended particles and
sediments, they are less susceptible to other biotic and abiotic processes, such as biotransformation, photolysis, and volatilization processes. Additionally, attenuation of
carbamazepine, citalopram, irbesartan, valsartan, and venlafaxine was strongly correlated with attenuation of soluble reactive phosphorus (SRP) and concentration of
total suspended solids (TSS). The half-lives of various pharmaceuticals ranged from
1.6 to 34 h, and dimetridazole, diazepam, and irbesartan had the highest half-lives,
as shown in Table 3.2.
3.4 Conclusions
The self-cleaning ability of a river can substantially attenuate pharmaceuticals discharged from various point and non-point sources. Biotransformation, sorption onto
sediment and solid particles, and phototransformation are the important attenuation
processes that decide the fate and transport of these compounds in the water-sediment
system. Several other factors, such as hydrogeological conditions, concentration and
composition of organic matter, and physical parameters, are also responsible. Various physical parameters that affect natural attenuation include river flow rate, reach
distance, depth, temperature, mixing, turbulence, and rate of exfiltration, and infiltration. The sorption behavior of any pharmaceutical is affected by sediment organic
fraction, type of sediment, surface sorption to mineral constituents, percentage distribution of clay, sand and silt, ion exchange capacity, pH of the system, and ability
to form complex metal ions.
Similarly, the extent of biotransformation is dependent upon ambient temperature, hydrogeology of the river, and physicochemical properties of the pharmaceuticals. The rate of biotransformation varies significantly in the aerobic, anaerobic,
and anoxic zones of rivers. The intensity of light, quantum yield, the concentration
of DOM, rate of formation of reactive oxygen species, and physicochemical properties of individual pharmaceuticals affect the phototransformation of pharmaceuticals
in the water-sediment systems. Pharmaceuticals belonging to the same therapeutic
class do not necessarily undergo the same degree of sorption, biotransformation, or
phototransformation.
References
Acuña V, von Schiller D, García-Galán MJ, Rodríguez-Mozaz S, Corominas L, Petrovic M, Poch
M, Barceló D, Sabater S (2015) Occurrence and in-stream attenuation of wastewater-derived
87
and functional groups. None of the physicochemical and molecular properties considered correlated with the mean values of v f . The v f values of some pharmaceuticals
were similar among the various study sites. However, for other pharmaceuticals, significant variability was obtained amongst sites. This may be attributed to varying
log K ow values. When hydrophobic compounds sorb onto suspended particles and
sediments, they are less susceptible to other biotic and abiotic processes, such as biotransformation, photolysis, and volatilization processes. Additionally, attenuation of
carbamazepine, citalopram, irbesartan, valsartan, and venlafaxine was strongly correlated with attenuation of soluble reactive phosphorus (SRP) and concentration of
total suspended solids (TSS). The half-lives of various pharmaceuticals ranged from
1.6 to 34 h, and dimetridazole, diazepam, and irbesartan had the highest half-lives,
as shown in Table 3.2.
3.4 Conclusions
The self-cleaning ability of a river can substantially attenuate pharmaceuticals discharged from various point and non-point sources. Biotransformation, sorption onto
sediment and solid particles, and phototransformation are the important attenuation
processes that decide the fate and transport of these compounds in the water-sediment
system. Several other factors, such as hydrogeological conditions, concentration and
composition of organic matter, and physical parameters, are also responsible. Various physical parameters that affect natural attenuation include river flow rate, reach
distance, depth, temperature, mixing, turbulence, and rate of exfiltration, and infiltration. The sorption behavior of any pharmaceutical is affected by sediment organic
fraction, type of sediment, surface sorption to mineral constituents, percentage distribution of clay, sand and silt, ion exchange capacity, pH of the system, and ability
to form complex metal ions.
Similarly, the extent of biotransformation is dependent upon ambient temperature, hydrogeology of the river, and physicochemical properties of the pharmaceuticals. The rate of biotransformation varies significantly in the aerobic, anaerobic,
and anoxic zones of rivers. The intensity of light, quantum yield, the concentration
of DOM, rate of formation of reactive oxygen species, and physicochemical properties of individual pharmaceuticals affect the phototransformation of pharmaceuticals
in the water-sediment systems. Pharmaceuticals belonging to the same therapeutic
class do not necessarily undergo the same degree of sorption, biotransformation, or
phototransformation.
References
Acuña V, von Schiller D, García-Galán MJ, Rodríguez-Mozaz S, Corominas L, Petrovic M, Poch
M, Barceló D, Sabater S (2015) Occurrence and in-stream attenuation of wastewater-derived