Abstract
The implementation of the new Water Reuse regulation in the European Union brings to the forefront the need to evaluate the risks of using wastewater for crop irrigation. Here, a two-tier ecotoxicological risk assessment was performed to evaluate the fate of wastewater-borne micropollutants in soil and their ecotoxicological impact on plants and soil microorganisms. To this end, two successive cultivation campaigns of lettuces were irrigated with wastewater (at agronomical dose (not spiked) and spiked with a mixture of 14 pharmaceuticals at 10 and 100 µg/L each) in a controlled greenhouse experiment. Over the two cultivation campaigns, an accumulation of PPCPs was observed in soil microcosms irrigated with wastewater spiked with 100 μg/L of PPCPs with the highest concentrations detected for clarithromycin, hydrochlorothiazide, citalopram, climbazole and carbamazepine. The abundance of bacterial and fungal communities remained stable over the two cultivation campaigns and was not affected by any of the irrigation regimes applied. Similarly, no changes were observed in the abundance of ammonium oxidizing archaea (AOA) and bacteria (AOB), nor in clade A of commamox no matter the cultivation campaign or the irrigation regime considered. Only a slight increase was detected in clade B of commamox bacteria after the second cultivation campaign. Sulfamethoxazole-resistant and -degrading bacteria were not impacted either. The irrigation regimes had only a limited effect on the bacterial evenness. However, in response to wastewater irrigation the structure of soil bacterial community significantly changed the relative abundance of Acidobacteria, Chloroflexi, Verrucomicrobia, Beta-, Gamma- and Deltaprotebacteria. Twenty-eight operational taxonomic units (OTUs) were identified as responsible for the changes observed within the bacterial communities of soils irrigated with wastewater or with water. Interestingly, the relative abundance of these OTUs was similar in soils irrigated with either spiked or non-spiked irrigation solutions. This indicates that under both agronomical and worst-case scenario the mixture of fourteen PPCPs had no effect on soil bacterial community.
Highlights
Water is a finite resource crucial for livestock and agricultural crop production
At the end of the second campaign, Simpson reciprocal significantly decreased in soils irrigated with wastewater spiked with 100 μg/L of PPCPs (p = 0.04). β-diversity analyses based on weighted and unweighted Unifrac distance matrices were plotted using Principal Coor dinate Analysis (PCoA) and showed a relatively good reproducibility between replicates from same irrigation regime, which grouped together
The soil bacterial community composition from soil irrigated with water clustered together with that of soil irrigated with spiked water (p > 0.139) and both were clearly separated from those found in soils irrigated with wastewater spiked or not with PPCPs
Summary
Water is a finite resource crucial for livestock and agricultural crop production. Agricultural practices alone account for up to 70% of water withdrawals. The effects of global change and water scarcity constitutes a major concern for the agricultural sector, especially in arid and semiarid regions and countries with poor water management practices. Within this context, the use of wastewater can overcome the shortage of freshwater resources for crop irrigation (Garcia and Pargament, 2015; Petrie et al, 2015). Water Reuse regulation that among others, defined the minimum quality requirements of wastewater for crop irrigation (European Comission, 2020). The environmental risks caused by water reuse in agriculture are on the top priority, environmental fate of wastewater-borne biotic and chemical contaminants and their possible ecotoxicological effects on soil living organisms and supported ecolog ical functions are still missing
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
