contamination. PhACs residues from these polluted sites [31–34] can contaminate
water resources (runoff, surface water; leaching, groundwater), which can be used
for crop irrigation, and indirectly contribute to both soil pollution and crop
contamination.
2 Processes Involved in the Fate of PhACs in Arable Soils
As described above PhACs reach the environment via different entry routes. They
reach soil via organic amendment (sewage sludge and farmyard manure) and crop
irrigation (wastewater) and water resources via discharge of treated wastewater from
wastewater plants in rivers and runoff and leaching from amended arable field. Once
they enter the environment, the principal processes governing their fate are found at
different degrees in both terrestrial and aquatic compartments. PhACs present in
solid and liquid phases interact with both abiotic and biotic compartments of the
environment.
In soils, PhACs are subject to several abiotic (sorption, photolysis, chemical
transformation) and biotic (bioaccumulation and biotransformation) processes,
which determine their ultimate distribution into the different environmental compartments [30, 35]. The rate and degree of each of those processes are determined by
PhACs physicochemical characteristics as well as pedoclimatic conditions including
temperature, humidity, and soil physiochemical characteristics [36–38].
Among the different mechanisms involved in the environmental fate of PhACs,
sorption to soil components is by far one of the most important. It implies their close
interactions with organic matter and mineral constituents of soils, involving ion
exchange, surface adsorption to mineral constituents, hydrogen bonding, and formation of complexes with ions such as Ca
2+ , Mg
2+ , Fe
+3 , or Al
3+ [30]. Examples of
PhACs with a strong tendency to bind to soil particles are found among those that are
poorly soluble such as the analgesic paracetamol, [39], the biocides triclosan and
triclocarban, and some antibiotics such as tetracyclines, macrolides, sulfamethazine
[40, 41], and quinolones, which form stable complexes through cation bridging to
clay minerals. As a result, PhACs remain adsorbed in soils for a long period of time
although lowly bioavailable to in soil living organisms [41–51].
On the contrary, the analgesics and anti-inflammatory compounds diclofenac,
ibuprofen, and naproxen, the β-blocker propranolol, and some antibiotics such as
sulfamethoxazole are less adsorbed to soils [38, 52–54] from where they can runoff
to surface waters or leach to groundwater after a heavy rainfall event [25, 54–
58]. This was also observed for carbamazepine, meprobamate, trimethoprim, and
primidone applied to soil via crop irrigation with spiked wastewater, thereby
confirming their low sorption to soil components and their relatively high mobility
in soil [56, 59–64]. In addition, PhACs present in the soluble fraction are not only
ready to leach to groundwater but also available for plant uptake [24, 65–70], macroand mesofauna bioaccumulation [71–73], and/or microbiota uptake and further
transformation [74].
Impact of PhACs on Soil Microorganisms
269
water resources (runoff, surface water; leaching, groundwater), which can be used
for crop irrigation, and indirectly contribute to both soil pollution and crop
contamination.
2 Processes Involved in the Fate of PhACs in Arable Soils
As described above PhACs reach the environment via different entry routes. They
reach soil via organic amendment (sewage sludge and farmyard manure) and crop
irrigation (wastewater) and water resources via discharge of treated wastewater from
wastewater plants in rivers and runoff and leaching from amended arable field. Once
they enter the environment, the principal processes governing their fate are found at
different degrees in both terrestrial and aquatic compartments. PhACs present in
solid and liquid phases interact with both abiotic and biotic compartments of the
environment.
In soils, PhACs are subject to several abiotic (sorption, photolysis, chemical
transformation) and biotic (bioaccumulation and biotransformation) processes,
which determine their ultimate distribution into the different environmental compartments [30, 35]. The rate and degree of each of those processes are determined by
PhACs physicochemical characteristics as well as pedoclimatic conditions including
temperature, humidity, and soil physiochemical characteristics [36–38].
Among the different mechanisms involved in the environmental fate of PhACs,
sorption to soil components is by far one of the most important. It implies their close
interactions with organic matter and mineral constituents of soils, involving ion
exchange, surface adsorption to mineral constituents, hydrogen bonding, and formation of complexes with ions such as Ca
2+ , Mg
2+ , Fe
+3 , or Al
3+ [30]. Examples of
PhACs with a strong tendency to bind to soil particles are found among those that are
poorly soluble such as the analgesic paracetamol, [39], the biocides triclosan and
triclocarban, and some antibiotics such as tetracyclines, macrolides, sulfamethazine
[40, 41], and quinolones, which form stable complexes through cation bridging to
clay minerals. As a result, PhACs remain adsorbed in soils for a long period of time
although lowly bioavailable to in soil living organisms [41–51].
On the contrary, the analgesics and anti-inflammatory compounds diclofenac,
ibuprofen, and naproxen, the β-blocker propranolol, and some antibiotics such as
sulfamethoxazole are less adsorbed to soils [38, 52–54] from where they can runoff
to surface waters or leach to groundwater after a heavy rainfall event [25, 54–
58]. This was also observed for carbamazepine, meprobamate, trimethoprim, and
primidone applied to soil via crop irrigation with spiked wastewater, thereby
confirming their low sorption to soil components and their relatively high mobility
in soil [56, 59–64]. In addition, PhACs present in the soluble fraction are not only
ready to leach to groundwater but also available for plant uptake [24, 65–70], macroand mesofauna bioaccumulation [71–73], and/or microbiota uptake and further
transformation [74].
Impact of PhACs on Soil Microorganisms
269