(Coriandrum sativum). They found that, consistently, uptake potential followed
ofloxacin > atenolol > diclofenac and that there was a minor influence on uptake
resulting from soil moisture depletion, whereby higher concentrations of the compounds were highest in plants grown under the higher soil moisture condition of 14%
(À4.26 kPa).
Similarly, the effect of soil moisture, as evaluated by drought stress in lettuce
plants, on the uptake of antibiotics and antibiotic-resistant Salmonella by lettuce was
investigated by Zhang et al. [80]. Using an experimental design where lettuce was
grown to maturity using clean freshwater then allowed to reach one of the three
wilting conditions (no wilting, mild wilting and severe wilting) prior to irrigation
with freshwater fortified with Salmonella and sulfamethoxazole, lincomycin and
oxytetracycline. Upon irrigation after wilting, all lettuce plants were able to recover,
confirming no permanent wilting damage. However, drought conditions did affect
concentrations with increasing concentration of lincomycin and oxytetracycline
corresponding to increased drought and the inverse results for sulfamethoxazole.
4.1.4 Impact of Irrigation System
Whilst the majority of pharmaceutical irrigation studies utilise or simulate drip
irrigation systems, only a few studies have looked at the impact that different
irrigation systems have on the accumulation of pharmaceuticals in plants irrigated
with reclaimed water. Bhalsod et al. [81] investigated how root and shoot concentrations of 11 pharmaceutical compounds differed between exposure via an overhead
irrigation and a drip irrigation system. Their study showed that overhead irrigation
significantly increased pharmaceutical concentrations in lettuce shoots even after
washing for tylosin, monensin and trimethoprim and highlights foliar sorption as a
potentially important mechanism for pharmaceutical incorporation. Concentrations
on a fresh weight basis ranging from 0.05 Æ 0.04 μg/kg for sulfadiazine to
345 Æ 139 μg/kg for carbamazepine, like other studies which have included carbamazepine, showed high levels of uptake and translocation into plant shoots.
Within subsurface drip irrigation systems, the potential to inject air has emerged
as a technique to increase crop yields and overcome root zone wetting issues.
D’Alessio et al. [82] investigated the potential impact of subsurface air injection
on pharmaceutical uptake by lettuce when drip irrigation of water fortified with
caffeine, carbamazepine and gemfibrozil. The added aeration increased lettuce plant
mass and root length and altered soil microbial communities. It also affected the
uptake of pharmaceuticals with increased uptake of carbamazepine and decreased
gemfibrozil observed with air injection.
Uptake and Effects of Pharmaceuticals in the Soil-Plant-Earthworm System
195
ofloxacin > atenolol > diclofenac and that there was a minor influence on uptake
resulting from soil moisture depletion, whereby higher concentrations of the compounds were highest in plants grown under the higher soil moisture condition of 14%
(À4.26 kPa).
Similarly, the effect of soil moisture, as evaluated by drought stress in lettuce
plants, on the uptake of antibiotics and antibiotic-resistant Salmonella by lettuce was
investigated by Zhang et al. [80]. Using an experimental design where lettuce was
grown to maturity using clean freshwater then allowed to reach one of the three
wilting conditions (no wilting, mild wilting and severe wilting) prior to irrigation
with freshwater fortified with Salmonella and sulfamethoxazole, lincomycin and
oxytetracycline. Upon irrigation after wilting, all lettuce plants were able to recover,
confirming no permanent wilting damage. However, drought conditions did affect
concentrations with increasing concentration of lincomycin and oxytetracycline
corresponding to increased drought and the inverse results for sulfamethoxazole.
4.1.4 Impact of Irrigation System
Whilst the majority of pharmaceutical irrigation studies utilise or simulate drip
irrigation systems, only a few studies have looked at the impact that different
irrigation systems have on the accumulation of pharmaceuticals in plants irrigated
with reclaimed water. Bhalsod et al. [81] investigated how root and shoot concentrations of 11 pharmaceutical compounds differed between exposure via an overhead
irrigation and a drip irrigation system. Their study showed that overhead irrigation
significantly increased pharmaceutical concentrations in lettuce shoots even after
washing for tylosin, monensin and trimethoprim and highlights foliar sorption as a
potentially important mechanism for pharmaceutical incorporation. Concentrations
on a fresh weight basis ranging from 0.05 Æ 0.04 μg/kg for sulfadiazine to
345 Æ 139 μg/kg for carbamazepine, like other studies which have included carbamazepine, showed high levels of uptake and translocation into plant shoots.
Within subsurface drip irrigation systems, the potential to inject air has emerged
as a technique to increase crop yields and overcome root zone wetting issues.
D’Alessio et al. [82] investigated the potential impact of subsurface air injection
on pharmaceutical uptake by lettuce when drip irrigation of water fortified with
caffeine, carbamazepine and gemfibrozil. The added aeration increased lettuce plant
mass and root length and altered soil microbial communities. It also affected the
uptake of pharmaceuticals with increased uptake of carbamazepine and decreased
gemfibrozil observed with air injection.
Uptake and Effects of Pharmaceuticals in the Soil-Plant-Earthworm System
195