of PhACs, commonly found in wastewater effluents and derived organic fertilizers,
on the soil microbial community.
Keywords Ecosystem services, Microbial activities, Microbial ecotoxicology,
Microbial function, Pharmaceuticals
1 Ways of Entrance of PhACs in Arable Soils
Every year, million tons of pharmaceutical active compounds (PhACs) are consumed worldwide for prophylaxis and curative treatments in human and veterinary
medicines [1, 2]. Following their ingestion, formulated PhACs enter the body where
they are partially assimilated by the organism and, thereafter, largely excreted
through feces and urine [3, 4]. On the one hand, excreted residues of PhACs used
in human medicine are collected in domestic and hospital sewage disposal systems
to reach wastewater treatment plants [5, 6]. Direct dumping of unused or expired
medication [7, 8] and illegal drugs [9] can also contribute to wastewater contamination. Since PhACs are relatively stable, conventional wastewater treatment plans
have proven to be moderately effective at removing them [10]. As a result, complex
mixtures of PhACs and their main metabolites are frequently found in treated
wastewater effluents discharged directly in the river and/or in sewage sludge applied
to arable soil as organic fertilizers [11, 12]. On the other hand, excreted veterinary
PhACs accumulate in livestock manure [13–16] in concentrations that can be
severalfold greater than in sewage sludge [17].
In arid or semiarid regions, such as the Mediterranean rim, where rainfalls are
uneven and water resources limited, the use of treated wastewater in crop irrigation
and groundwater recharge constitutes a promising alternative to release green water
pressure on water cycle. Irrigation of crop with wastewater provides not only water
but also nutrients to plant [18–20]. This agricultural practice may thereby reduce the
application of agrochemical fertilizers, improve plant growth, and limit the wastewater discharged in rivers, thereby decreasing the PhACs pressure on surface water
resources especially during the low-water period. Similarly, organic amendment of
arable soils with livestock manure and/or sewage sludge/biosolid is also known to be
beneficial for mineral fertilization of soil (especially nitrogen) and plant nutrition: it
contributes to the maximization of crop yields [21, 22]. However, both practices lead
to the release of numerous micro-pollutants including PhACs into arable soils with
unknown consequences on both their abiotic and biotic components [23–
28]. Although introduced PhACs concentrations are quite low, their repeated input
in soil may lead to their accumulation, cause toxic effects to in soil living organisms,
and transfer to surrounding aquatic compartments [29, 30].
In addition to diffuse contamination sources in arable soils, improper disposal of
drugs or pharmaceutical waste products and accidental spills from pharmaceutical
manufacturing plants and hospitals constitute important point sources of
268
S. Gallego and F. Martin-Laurent
on the soil microbial community.
Keywords Ecosystem services, Microbial activities, Microbial ecotoxicology,
Microbial function, Pharmaceuticals
1 Ways of Entrance of PhACs in Arable Soils
Every year, million tons of pharmaceutical active compounds (PhACs) are consumed worldwide for prophylaxis and curative treatments in human and veterinary
medicines [1, 2]. Following their ingestion, formulated PhACs enter the body where
they are partially assimilated by the organism and, thereafter, largely excreted
through feces and urine [3, 4]. On the one hand, excreted residues of PhACs used
in human medicine are collected in domestic and hospital sewage disposal systems
to reach wastewater treatment plants [5, 6]. Direct dumping of unused or expired
medication [7, 8] and illegal drugs [9] can also contribute to wastewater contamination. Since PhACs are relatively stable, conventional wastewater treatment plans
have proven to be moderately effective at removing them [10]. As a result, complex
mixtures of PhACs and their main metabolites are frequently found in treated
wastewater effluents discharged directly in the river and/or in sewage sludge applied
to arable soil as organic fertilizers [11, 12]. On the other hand, excreted veterinary
PhACs accumulate in livestock manure [13–16] in concentrations that can be
severalfold greater than in sewage sludge [17].
In arid or semiarid regions, such as the Mediterranean rim, where rainfalls are
uneven and water resources limited, the use of treated wastewater in crop irrigation
and groundwater recharge constitutes a promising alternative to release green water
pressure on water cycle. Irrigation of crop with wastewater provides not only water
but also nutrients to plant [18–20]. This agricultural practice may thereby reduce the
application of agrochemical fertilizers, improve plant growth, and limit the wastewater discharged in rivers, thereby decreasing the PhACs pressure on surface water
resources especially during the low-water period. Similarly, organic amendment of
arable soils with livestock manure and/or sewage sludge/biosolid is also known to be
beneficial for mineral fertilization of soil (especially nitrogen) and plant nutrition: it
contributes to the maximization of crop yields [21, 22]. However, both practices lead
to the release of numerous micro-pollutants including PhACs into arable soils with
unknown consequences on both their abiotic and biotic components [23–
28]. Although introduced PhACs concentrations are quite low, their repeated input
in soil may lead to their accumulation, cause toxic effects to in soil living organisms,
and transfer to surrounding aquatic compartments [29, 30].
In addition to diffuse contamination sources in arable soils, improper disposal of
drugs or pharmaceutical waste products and accidental spills from pharmaceutical
manufacturing plants and hospitals constitute important point sources of
268
S. Gallego and F. Martin-Laurent