Identification of transformation products of carbamazepine in lettuce crops irrigated with Ultraviolet-C treated water

Remediation of pesticides in commercial farm soils by solarization and ozonation techniques

Soil contamination by pesticides is a growing environmental problem. Even though nowadays numerous soil remediation technologies are available, most of them have not been tested at field scale. This study attempts to demonstrate the efficiency of solarization-ozonation techniques for the removal of twelve pesticides at full scale. Initial solarization and ozonation trials were conducted in plots located in a greenhouse using freshly and aged contaminated soils under controlled pilot conditions. The combination of solarization and ozonation treatment was efficient for all the studied pesticides both in freshly and in aged contaminated soils, being the lower degradation values found for the second type. This low removal suggests that the increase of pesticides' adsorption on soil resulting from ageing decreases their availability. Once the essays were carried out at pilot scale, the solarization-ozonation applicability was evaluated in a commercial farm soil. This trial was carried out in a greenhouse whose soil had previously been contaminated with some of the pesticides studied. A significant degradation (53.8%) was observed after 40 days of treatment. Pesticides' main metabolites were identified during the different remediation experiments. In addition, the cost of the combined solarization and ozonation technology was evaluated. Finally, our results suggest that this combination of techniques could be considered a promising technology to degrade pesticides in soil.

Detecting the sources of chemicals in the Black Sea using non-target screening and deep learning convolutional neural networks

The Black Sea is an important ecosystem, which is affected by various anthropogenic pressures, such as shipping activities and wastewater inputs from large coastal cities. Significant loads of chemical pollutants are being continuously brought in by major European rivers. This study investigated the spatial distribution of chemicals in the Ukrainian shelf (the northwestern part of the Black Sea) and their main sources. Chemical occurrence data used in the study was generated within the Joint Black Sea Surveys (JBSS), which took place in 2016 and 2017 as a part of the EU/UNDP EMBLAS II project (www.emblasproject.org). During the JBSS, seawater samples were analyzed by a non-target screening workflow using liquid chromatography high-resolution mass spectrometry (LC-HRMS). Open-source algorithms were applied to generate a combined dataset of 30,489 detected chemical signals and their intensities. Out of these, 35 compounds were tentatively identified by the application of a non-target screening identification workflow based on automated matching of their mass spectra against those in available mass spectral libraries. The dataset was used to generate images, representing spatial distribution of each of the signals. These images were then used as an input to a deep learning convolutional neural network classification model. The study resulted in the development of an open-source end-to-end workflow for the estimation of the pollution load by chemicals contributed by the two major inflowing rivers (Danube and Dnieper) and other, so far unidentified, sources. A dedicated dashboard was built to facilitate data visualization per detected signal/compound. The presented model proved to be especially useful at the prioritization of signals of unknown compounds, which is of key importance for the follow up structure elucidation efforts of bulky non-target screening data. The deep learning approach for peak prioritization of unknown chemicals in the environment has been used for the first time.

Fate and impact of wastewater-borne micropollutants in lettuce and the root-associated bacteria

The reuse of water for agricultural practices becomes progressively more important due to increasing demands for a transition to a circular economy. Treated wastewater can be an alternative option of blue water used for the irrigation of crops but its risks need to be evaluated. This study assesses the uptake and metabolization of pharmaceuticals and personal care products (PPCPs) derived from treated wastewater into lettuce as well as the impact on root-associated bacteria under a realistic and worst-case scenario. Lettuce was grown in a controlled greenhouse and irrigated with water or treated wastewater spiked with and without a mixture of fourteen different PPCPs at 10 μg/L or 100 μg/L. After harvesting the plants, the same soil was reused for a consecutive cultivation campaign to test for the accumulation of PPCPs. Twelve out of fourteen spiked PPCPs were detected in lettuce roots, and thirteen in leaves. In roots, highest concentrations were measured for sucralose, sulfamethoxazole and citalopram, while sucralose, acesulfame and carbamazepine were the highest in leaves. Higher PPCP concentrations were found in lettuce roots irrigated with spiked treated wastewater than in those irrigated with spiked water. The absolute bacterial abundance remained stable over both cultivation campaigns and was not affected by any of the treatments (type of irrigation water (water vs. wastewater) nor concentration of PPCPs). However, the irrigation of lettuce with treated wastewater had a significant effect on the microbial α-diversity indices at the end of the second cultivation campaign, and modified the structure and community composition of root-associated bacteria at the end of both campaigns. Five and fourteen bacterial families were shown to be responsible for the observed changes at the end of the first and second cultivation campaign, respectively. Relative abundance of Haliangium and the clade Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium was significantly affected in response to PCPPs exposure. Caulobacter, Cellvibrio, Hydrogenophaga and Rhizobacter were significantly affected in microcosms irrigated with wastewater.

Assessment of reclaimed agro-wastewater polluted with insecticide residues for irrigation of growing lettuce (Lactuca sativa L) using solar photocatalytic technology

Scientific literature is full of works studying the removal of different pollutants from water through different Advanced Oxidation Processes (AOPs). Many of them only suggest it is reused for agricultural purposes or for small crops in pots. This study is based on the reuse of reclaimed agricultural wastewater contaminated with four insecticides (chlorantraniliprole, imidacloprid, pirimicarb and thiamethoxam) for growing lettuce in field conditions. First, solar photocatalysis with TiO2/Na2S2O8 was used on a pilot plant in a sunny area (Murcia, SE of Spain) as an environmentally friendly technology to remove insecticide residues and their main reaction intermediates from contaminated water. The necessary fluence (H, kJ m-2) to accomplish 90% removal (H90) ranged from 0.12 to 1212 kJ m-2 for pirimicarb and chlorantraniliprole, respectively. Only six (derived from imidacloprid, pirimicarb and thiametoxam) of 18 transformation intermediate products studied were detected in reclaimed water during the photoperiod (2000 kJ m-2 of accumulated UVA radiation) although all of them were totally photodegraded after a fluence of 1250 kJ m-2. Secondly, reclaimed agro-wastewater was used to irrigate two lettuce crops grown under greenhouse conditions and under agricultural field conditions. In no cases, insecticide residues nor their TIPs were noticed above their respective LOQs (limits of quantification) in soil and lettuce samples (between 0.03 and 0.04 μg kg-1 for pirimicarb and 2.49 and 2.23 μg kg-1 for thiamethoxam, respectively) when they were irrigated with reclaimed water, while residues of the four insecticides and some of their intermediates were found in soil and lettuce by the end of cultivation when they were irrigated with non-reclaimed contaminated water. According to the results, this technology can be applied in a sustainable way, mainly in areas with water scarcity and high solar radiation, contributing to water utilisation in drought areas and the use of renewable energy.

Investigation of Photocatalysis by Mesoporous Titanium Dioxide Supported on Glass Fibers as an Integrated Technology for Water Remediation

The photocatalytic efficiency of an innovative UV-light catalyst consisting of a mesoporous TiO2 coating on glass fibers was investigated for the degradation of pharmaceuticals (PhACs) in wastewater effluents. Photocatalytic activity of the synthesized material was tested, for the first time, on a secondary wastewater effluent spiked with nine PhACs and the results were compared with the photolysis used as a benchmark treatment. Replicate experiments were performed in a flow reactor equipped with a UV radiation source emitting at 254 nm. Interestingly, the novel photocatalyst led to the increase of the degradation of carbamazepine and trimethoprim (about 2.2 times faster than the photolysis). Several transformation products (TPs) resulting from both the spiked PhACs and the compounds naturally occurring in the secondary wastewater effluent were identified through UPLC-QTOF/MS/MS. Some of them, produced mainly from carbamazepine and trimethoprim, were still present at the end of the photolytic treatment, while they were completely or partially removed by the photocatalytic treatment.

Photocatalytic degradation of four insecticides and their main generated transformation products in soil and pepper crop irrigated with reclaimed agro-wastewater under natural sunlight

This work is the first-ever study of the concurrence of four insecticides (chlorantraniliprole, imidacloprid, pirimicarb and thiamethoxam) and their main transformation products (TPs) in soil and pepper crop irrigated with reclaimed and non-reclaimed water under agricultural field conditions. Field experiments were conducted using different irrigation supplies: control water (CW), wastewater polluted with phytosanitary commercial products containing the studied insecticides (WW) and reclaimed wastewater after a photocatalytic processing with TiO₂/Na₂S₂O₈ at pilot plant under sunlight (RWW). Photocatalytic treatments removed most of the insecticides and their TPs generated during the photoperiod. Neither target insecticides nor their TPs were detected in pepper samples when CW and RWW were used as irrigation source, whereas the four insecticides and two TPs were detected when WW was used. In the experiment carried out with WW, all insecticides and eight TPs were detected in soil samples. The impact of using reclaimed water on the quality of pepper crop was also assessed, showing barely any significant difference.

Assessment of the presence of transformation products of pharmaceuticals in agricultural environments irrigated with reclaimed water by wide-scope LC-QTOF-MS suspect screening

The transformation that pharmaceuticals can undergo during the water reclamation cycle, or by biotic/abiotic reactions when reclaimed water (RW) is used for irrigation, can lead to the presence of transformation products (TPs) in agricultural environments. However, data on TPs in real crops are scarce. Herein, a suspect screening approach was applied for the comprehensive investigation of 262 potential TPs, associated with 20 prioritised pharmaceuticals found in real tomato crops exposed to long-term RW irrigation. The occurrence and fate of the TPs was evaluated by the retrospective analysis of RW, soil, leave and tomato samples from 4 intensive production greenhouses. Sample analysis was accomplished by liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). Up to 18 TPs were tentatively identified, of which 2 were not previously reported. 7 TPs were finally confirmed with analytical standards. 5 TPs were determined in RW, 15 TPs in soil and 2 TPs in leaves. Remarkably, the investigated TPs were not found in tomato fruits. These results shed light on the variety of TPs that can be found in the water reuse cycle and contribute to the assessment of the global risks of wastewater reuse and the safety of the vegetable and fruit production system.

Appraisal of water matrix on the removal of fungicide residues by heterogeneous photocatalytic treatment using UV-LED lamp as light source

In this study, the photocatalytic degradation of four fungicides, myclobutanil, penconazole and difenoconazole (triazole compounds) and boscalid (carboxamide), has been examined in different aqueous matrices (tap water, irrigation water and two WWPT effluents). Experiments were conducted at laboratory scale with different reagents-zinc oxide (ZnO), titanium dioxide (TiO₂), sodium persulphate (Na₂S₂O₈) and the combined systems ZnO/Na₂S₂O₈ and TiO₂/Na₂S₂O₈-in water exposed to UV-LED irradiation. Previously, the effect of catalyst and oxidant loading on the disappearance kinetics of the different fungicides was assessed to know maximum degradation efficiency. The influence of water matrices and pesticide loading in removal effectiveness has been evaluated. It was observed a greater efficiency in processes conducted using the tandems ZnO/Na₂S₂O₈ and TiO₂/Na₂S₂O₈ in irrigation and tap waters. Results showed that UV-LED are a suitable alternative for tackling the removal of organic pollutants in water.

Impact of long-term irrigation with municipal reclaimed wastewater on the uptake and degradation of organic contaminants in lettuce and leek

A two years drip irrigation of lettuce and leek crops with treated municipal wastewater without and with spiking with fourteen wastewater relevant contaminants at 10 μg/L concentration level was conducted under greenhouse cultivation conditions to investigate their potential accumulation in soil and leaves and to assess human health related risks. Lettuce and leek crops were selected as a worse-case scenario since leafy green vegetable has a high potential for organic contaminants uptake. The results revealed limited accumulation of contaminants in soil and plant leaves, their concentration levels being in the range of 1-30 ng/g and 1-660 ng/g range in soil and leaves, respectively. This was likely related to abiotic and biotic transformation or simply binding processes in soil, which limited contaminants plant uptake. This assumption was underpinned by studies of the enantiomeric fractionation of chiral compounds (e.g. climbazole and metoprolol) in soil as pieces of evidence of biodegradation and by the identification of transformation products or metabolites in leaves by means of liquid chromatography - high resolution - mass spectrometry using a suspect screening workflow. The high bioconcentration factors were not limited to compounds with intermediate Dow (100 to 1000) such as carbamazepine but also observed for hydrophilic compounds such as clarithromycin, hydrochlorothiazide and the food additives acesulfame and sucralose. This result assumed that accumulation was not only driven by passive processes (e.g. lipoidal diffusion through lipid bilayer cell membranes or Casparian strip) but might be supported by carrier-mediated transporters. As a whole, this study confirmed earlier reports on the a de minimis human health risk related to the consumption of raw leafy green vegetable irrigated with domestic TWW containing organic contaminants residues.

Untargeted Metabolomics Studies on Drug-Incubated Phragmites australis Profiles

Plants produce a huge number of functionally and chemically different natural products that play an important role in linking the plant with the adjacent environment. Plants can also absorb and transform external organic compounds (xenobiotics). Currently there are only a few studies concerning the effects of xenobiotics and their transformation products on plant metabolites using a mass spectrometric untargeted screening strategy. This study was designed to investigate the changes of the Phragmites australis metabolome following/after diclofenac or carbamazepine incubation, using a serial coupling of reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) combined with accurate high-resolution time-of-flight mass spectrometer (TOF-MS). An untargeted screening strategy of metabolic fingerprints was developed to purposefully compare samples from differently treated P. australis plants, revealing that P. australis responded to each drug differently. When solvents with significantly different polarities were used, the metabolic profiles of P. australis were found to change significantly. For instance, the production of polyphenols (such as quercetin) in the plant increased after diclofenac incubation. Moreover, the pathway of unsaturated organic acids became more prominent, eventually as a reaction to protect the cells against reactive oxygen species (ROS). Hence, P. australis exhibited an adaptive mechanism to cope with each drug. Consequently, the untargeted screening approach is essential for understanding the complex response of plants to xenobiotics.

Enrichment of endophytic Actinobacteria in roots and rhizomes of Miscanthus × giganteus plants exposed to diclofenac and sulfamethoxazole

This study investigates how wastewater containing 2 mg l^-1 of sulfamethoxazole (SMX) and 2 mg l^-1 of diclofenac (DCF) affects the composition of bacterial communities present in the roots and rhizomes of Miscanthus × giganteus plants grown in laboratory-scale constructed wetlands. Bacterial communities in plant roots and rhizomes were identified in treated and control samples by 16S rRNA amplicon sequencing. Moreover, bacterial endophytes were isolated in R2A and 1/10 869 media and screened for their ability to metabolize SMX and DCF in liquid medium by HPLC. Our results show significant changes in the abundance of main genera, namely Sphingobium and Streptomyces between control and treated plants. Around 70% of the strains isolated from exposed plants belonged to the phylum Actinobacteria and were classified as Streptomyces, Microbacterium, and Glycomyces. In non-exposed plants, Proteobacteria represented 43.5% to 63.6% of the total. We identified 17 strains able to remove SMX and DCF in vitro. From those, 76% were isolated from exposed plants. Classified mainly as Streptomyces, they showed the highest SMX (33%) and DCF (41%) removal efficiency. These isolates, alone or in combination, might be used as bio-inoculants in constructed wetlands to enhance the phytoremediation of SMX and DCF during wastewater treatment.

Presence and Natural Treatment of Organic Micropollutants and their Risks after 100 Years of Incidental Water Reuse in Agricultural Irrigation

The aim of the research was to show the presence of micropollutants contained in the wastewater of Mexico City within the distribution canals of the Mezquital Valley (MV), as well as their retention in agricultural soil and aquifers. This system constitutes the world's oldest and largest example of the use of untreated wastewater for agricultural irrigation. The artificial recharge associated with the MV aquifers, with groundwater extracted for human consumption showing its importance as a water resource for Mexico City. The results of sampling show the presence of 18 compounds, with 10 of these considered as endocrine disruptor compounds (EDCs). The concentration of these pollutants ranged from 2 ng/L for 17 β-estradiol to 99 ng/L for DEHP, with these values decreasing throughout the course of the canals due to the wastewater dilution factor, their retention in agricultural soil, and their accumulation in the local aquifer. The main mechanisms involved in natural attenuation are adsorption, filtration, and biodegradation. Drinking water equivalent levels (DWELs) were estimated for 11 compounds with regard to acceptable daily intakes (ADIs), by assuming local exposure parameters for a rural Mexican population. These were compared with the maximum groundwater concentrations (Cgw) to screen the potential risks. The very low ratios of Cgw to DWELs indicate no appreciable human health risk from the presence of trace concentrations of these compounds in the source of drinking water in the MV. Despite this, far from being exceeded after more than 100 years of irrigation with residual water, the natural soil attenuation seems to remain stable.