Pharmaceuticals, herbicides, and disinfectants in agricultural water sources

Direct and indirect photolysis of oxolinic acid in surface waters and its inhibition by antioxidant effects

Oxolinic acid is a quinolone antibiotic used in aquaculture to prevent and treat animal diseases. Because of its application and the large expansion of aquaculture in the latest decades, oxolinic acid enters environmental waters through the effluents of aquaculture facilities, posing concerns due to its potential adverse effects on aquatic ecosystems. It is thus important to study the fate of this antibiotic in water bodies. This work investigated the reactivity of the anionic form of oxolinic acid (OxA) by direct and indirect photolysis. The quantum yield of direct photolysis and the bimolecular rate constants of OxA reactions with reactive species photochemically produced in fresh- and seawater (i.e., HO•, CO3•-, triplet states of dissolved organic matter, 1O2, and Br2•-) were determined through steady-state irradiation experiments and laser flash photolysis measurements. Results showed that OxA photoreactivity is significant, in particular towards HO• and CO3•- radicals. However, the direct photolysis and reactions with CO3•- and the triplet states of dissolved organic matter were found to be significantly inhibited in the presence of phenol, here used as a representative compound for antioxidant dissolved organic matter, most likely because of a back-reduction process. Photochemical modeling predicted an antibiotic half-life time of some days in fresh- and seawater, showing that OxA degradation is mainly due to direct photolysis in both environments plus reactions with CO3•- (freshwater) and Br2•- (seawater).

Azithromycin removal using pine bark, oak ash and mussel shell

Adsorption is considered an interesting option for removing antibiotics from the environment because of its simple design, low cost, and potential efficiency. In this work we evaluated three by-products (pine bark, oak ash, and mussel shell) as bio-adsorbents for the antibiotic azithromycin (AZM). Furthermore, they were added at doses of 48 t ha-1 to four different soils, then comparing AZM removal for soils with and without bio-adsorbents. Batch-type experiments were used, adding AZM concentrations between 2.5 and 600 μmol L-1 to the different bio-adsorbents and soil + bio-adsorbent mixtures. Regarding the bio-adsorbents, oak ash showed the best adsorption scores (9600 μmol kg-1, meaning >80% retention), followed by pine bark (8280 μmol kg-1, 69%) and mussel shell (between 3000 and 6000 μmol kg-1, 25-50% retention). Adsorption data were adjusted to different models (Linear, Freundlich and Langmuir), showing that just mussel shell presented an acceptable fitting to the Freundlich equation, while pine bark and oak ash did not present a good adjustment to any of the three models. Regarding desorption, the values were always below the detection limit, indicating a rather irreversible adsorption of AZM onto these three by-products. Furthermore, the results showed that when the lowest concentrations of AZM were added to the not amended soils they adsorbed 100% of the antibiotic, whereas when the highest concentrations of AZM were spread, the adsorption decreased to 55%. However, when any of the three bio-adsorbents was added to the soils, AZM adsorption reached 100% for all the antibiotic concentrations used. Desorption was null in all cases for both soils with and without bio-adsorbents. These results, corresponding to an investigation carried out for the first time for the antibiotic AZM, can be seen as relevant in the search of low-cost alternative treatments to face environmental pollution caused by this emerging contaminant.

Unveiling the hidden risks: Pesticide residues in aquaculture systems

The present study systematically assessed the presence and ecological risks of 79 pesticides in various aquaculture systems, namely pond aquaculture (PA), greenhouse aquaculture (GA), and raceway aquaculture (RA) at different aquaculture stages, along with evaluating the pesticide removal of four tailwater treatment systems. Sixteen herbicides and two fungicides were identified, with the total concentrations ranging from 8.33 ng/L to 3248.45 ng/L. The PA system demonstrated significantly higher concentrations (p < 0.05) and a wider range of pesticide residues compared to the GA and RA systems. Prometryn, simetryn, atrazine, and thifluzamide were found to be the predominant pesticides across all three aquaculture modes, suggesting their significance as pollutants that warrant monitoring. Additionally, the findings indicated that the early aquaculture stage exhibits the highest levels of pesticide concentration, underscoring the importance of heightened monitoring and regulatory interventions during this phase. Furthermore, among the four tailwater treatment systems analyzed, the recirculating tailwater treatment system exhibited the highest efficacy in pesticide removal. A comprehensive risk assessment revealed minimal ecological risks in both the aquaculture and tailwater environments. However, the pesticide mixtures present high risks to algae and low to medium risks to aquatic invertebrates and fish, particularly during the early stages of aquaculture. Simetryn and prometryn were identified as high-risk pesticides. Based on the prioritization index, simetryn, prometryn, diuron, and ametryn are recommended for prioritization in risk assessment. This study offers valuable data for pesticide control and serves as a reference for the establishment of a standardized pesticide monitoring and management system at various stages of aquaculture.

A Review on Fluoroquinolones' Toxicity to Freshwater Organisms and a Risk Assessment

Fluoroquinolones (FQs) have achieved significant success in both human and veterinary medicine. However, regulatory authorities have recommended limiting their use, firstly because they can have disabling side effects; secondly, because of the need to limit the spread of antibiotic resistance. This review addresses another concerning consequence of the excessive use of FQs: the freshwater environments contamination and the impact on non-target organisms. Here, an overview of the highest concentrations found in Europe, Asia, and the USA is provided, the sensitivity of various taxa is presented through a comparison of the lowest EC50s from about a hundred acute toxicity tests, and primary mechanisms of FQ toxicity are described. A risk assessment is conducted based on the estimation of the Predicted No Effect Concentration (PNEC). This is calculated traditionally and, in a more contemporary manner, by constructing a normalized Species Sensitivity Distribution curve. The lowest individual HC5 (6.52 µg L-1) was obtained for levofloxacin, followed by ciprofloxacin (7.51 µg L-1), sarafloxacin and clinafloxacin (12.23 µg L-1), and ofloxacin (17.12 µg L-1). By comparing the calculated PNEC with detected concentrations, it is evident that the risk cannot be denied: the potential impact of FQs on freshwater ecosystems is a further reason to minimize their use.

Mitigating risks and maximizing sustainability of treated wastewater reuse for irrigation

Scarcity of freshwater for agriculture has led to increased utilization of treated wastewater (TWW), establishing it as a significant and reliable source of irrigation water. However, years of research indicate that if not managed adequately, TWW may deleteriously affect soil functioning and plant productivity, and pose a hazard to human and environmental health. This review leverages the experience of researchers, stakeholders, and policymakers from Israel, the United-States, and Europe to present a holistic, multidisciplinary perspective on maximizing the benefits from municipal TWW use for irrigation. We specifically draw on the extensive knowledge gained in Israel, a world leader in agricultural TWW implementation. The first two sections of the work set the foundation for understanding current challenges involved with the use of TWW, detailing known and emerging agronomic and environmental issues (such as salinity and phytotoxicity) and public health risks (such as contaminants of emerging concern and pathogens). The work then presents solutions to address these challenges, including technological and agronomic management-based solutions as well as source control policies. The concluding section presents suggestions for the path forward, emphasizing the importance of improving links between research and policy, and better outreach to the public and agricultural practitioners. We use this platform as a call for action, to form a global harmonized data system that will centralize scientific findings on agronomic, environmental and public health effects of TWW irrigation. Insights from such global collaboration will help to mitigate risks, and facilitate more sustainable use of TWW for food production in the future.

Pollutants in aquatic system: a frontier perspective of emerging threat and strategies to solve the crisis for safe drinking water

Water is an indispensable natural resource and is the most vital substance for the existence of life on earth. However, due to anthropogenic activities, it is being polluted at an alarming rate which has led to serious concern about water shortage across the world. Moreover, toxic contaminants released into water bodies from various industrial and domestic activities negatively affect aquatic and terrestrial organisms and cause serious diseases such as cancer, renal problems, gastroenteritis, diarrhea, and nausea in humans. Therefore, water treatments that can eliminate toxins are very crucial. Unfortunately, pollution treatment remains a difficulty when four broad considerations are taken into account: effectiveness, reusability, environmental friendliness, and affordability. In this situation, protecting water from contamination or creating affordable remedial techniques has become a serious issue. Although traditional wastewater treatment technologies have existed since antiquity, they are both expensive and inefficient. Nowadays, advanced sustainable technical approaches are being created to replace traditional wastewater treatment processes. The present study reviews the sources, toxicity, and possible remediation techniques of the water contaminants.

Herbicides in Water Sources: Communicating Potential Risks to the Population of Mangaung Metropolitan Municipality, South Africa

Pesticides are an important tool for maintaining and improving the global population's standard of living. However, their presence in water resources is concerning due to their potential consequences. Twelve water samples from rivers, dams/reservoirs, and treated drinking water were collected from Mangaung Metropolitan Municipality in South Africa. The collected samples were analysed using high-performance liquid chromatography linked to a QTRAP hybrid triple quadrupole ion trap mass spectrometer. The ecological and human health risks were assessed by risk quotient and human health risk assessment methods, respectively. Herbicides, such as atrazine, metolachlor, simazine and terbuthylazine, were analysed in water sources. The average concentrations of simazine in rivers (1.82 mg/L), dams/reservoirs (0.12 mg/L), and treated drinking water (0.03 mg/L) were remarkable among all four herbicides detected. Simazine, atrazine, and terbuthylazine posed high ecological risks for both acute and chronic toxicity in all water sources. Moreover, simazine is the only contaminant in the river water that poses a medium carcinogenic risk to adult. It can be concluded that the level of herbicide detected in water sources may affect aquatic life and human beings negatively. This study may aid in the development of pesticide pollution management and risk reduction strategies within the municipality.

A Current Review of Water Pollutants in American Continent: Trends and Perspectives in Detection, Health Risks, and Treatment Technologies

Currently, water pollution represents a serious environmental threat, causing an impact not only to fauna and flora but also to human health. Among these pollutants, inorganic and organic pollutants are predominantly important representing high toxicity and persistence and being difficult to treat using current methodologies. For this reason, several research groups are searching for strategies to detect and remedy contaminated water bodies and effluents. Due to the above, a current review of the state of the situation has been carried out. The results obtained show that in the American continent a high diversity of contaminants is present in the water bodies affecting several aspects, in which in some cases, there exists alternatives to realize the remediation of contaminated water. It is concluded that the actual challenge is to establish sanitation measures at the local level based on the specific needs of the geographical area of interest. Therefore, water treatment plants must be designed according to the contaminants present in the water of the region and tailored to the needs of the population of interest.

Updated knowledge, partitioning and ecological risk of pharmaceuticals and personal care products in global aquatic environments

Over the last few decades, the occurrence of pharmaceuticals and personal care products (PPCPs) in aquatic environments has generated increasing public concern. In this review, data on the presence of PPCPs in environmental compartments from the past few years (2014-2022) are summarized by carrying out a critical survey of the partitioning among water, sediment, and aquatic organisms. From the available articles on PPCP occurrence in the environment, in Web of Science and Scopus databases, 185 articles were evaluated. Diclofenac, carbamazepine, caffeine, ibuprofen, ciprofloxacin, and sulfamethoxazole were reported to occur in 85% of the studies in at least one of the mentioned matrices. Risk assessment showed a moderate to high environmental risk for these compounds worldwide. Moreover, bioconcentration factors showed that sulfamethoxazole and trimethoprim can bioaccumulate in aquatic organisms, while ciprofloxacin and triclosan present bioaccumulation potential. Regarding spatial distribution, the Asian and European continents presented most studies on the occurrence and effects of PPCPs on the environment, while Africa and Asia are the most contaminated continents. In addition, the impact of COVID-19 on environmental contamination by PPCPs is discussed.

Variations in Bacterial Communities and Antibiotic Resistance Genes Across Diverse Recycled and Surface Water Irrigation Sources in the Mid-Atlantic and Southwest United States: A CONSERVE Two-Year Field Study

Reduced availability of agricultural water has spurred increased interest in using recycled irrigation water for U.S. food crop production. However, there are significant knowledge gaps concerning the microbiological quality of these water sources. To address these gaps, we used 16S rRNA gene and metagenomic sequencing to characterize taxonomic and functional variations (e.g., antimicrobial resistance) in bacterial communities across diverse recycled and surface water irrigation sources. We collected 1 L water samples (n = 410) between 2016 and 2018 from the Mid-Atlantic (12 sites) and Southwest (10 sites) U.S. Samples were filtered, and DNA was extracted. The V3-V4 regions of the 16S rRNA gene were then PCR amplified and sequenced. Metagenomic sequencing was also performed to characterize antibiotic, metal, and biocide resistance genes. Bacterial alpha and beta diversities were significantly different (p < 0.001) across water types and seasons. Pathogenic bacteria, such as Salmonella enterica, Staphylococcus aureus, and Aeromonas hydrophilia were observed across sample types. The most common antibiotic resistance genes identified coded against macrolides/lincosamides/streptogramins, aminoglycosides, rifampin and elfamycins, and their read counts fluctuated across seasons. We also observed multi-metal and multi-biocide resistance across all water types. To our knowledge, this is the most comprehensive longitudinal study to date of U.S. recycled water and surface water used for irrigation. Our findings improve understanding of the potential differences in the risk of exposure to bacterial pathogens and antibiotic resistance genes originating from diverse irrigation water sources across seasons and U.S. regions.

Extended Spectrum β-Lactamase Activity and Cephalosporin Resistance in Escherichia coli from U.S. Mid-Atlantic Surface and Reclaimed Water

Phylogenetic distribution and extended spectrum β-lactamase (ESBL) activity of Escherichia coli recovered from surface and reclaimed water in the mid-Atlantic U.S. were evaluated. Among 488 isolates, phylogroups B1 and A were the most and least prevalent, respectively. Water type, but not season, affected phylogroup distribution. The likelihood of detecting group A isolates was higher in reclaimed than pond (P < 0.01), freshwater river (P < 0.01) or brackish river (P < 0.05) water. Homogeneity in group distribution was lowest in pond water, where group B1 comprised 50% of isolates. Only 16 (3.3%) isolates exhibited phenotypic resistance to one or more cephalosporins tested and only four had ESBL activity, representing groups B1, B2 isolates, and D. Phylogroup was a factor in antimicrobial resistance (P < 0.05), with group A (8.7%) and D (1.6%) exhibiting the highest and lowest rates. Resistance to cefoxitin was the most prevalent. Multi- versus single drug resistance was affected by phylogroup (P < 0.05) and more likely in groups D and B1 than A which carried resistance to cefoxitin only. The most detected β-lactam resistance genes were bla_CMY-2 and bla_TEM. Water type was a factor for bla_CTX-M gene detection (P < 0.05). Phenotypic resistance to cefotaxime, ceftriaxone, cefuroxime and ceftazidime, and genetic determinants for ESBL-mediated resistance were found predominantly in B2 and D isolates from rivers and reclaimed water. Overall, ESBL activity and cephalosporin resistance in reclaimed and surface water isolates were low. Integrating data on ESBL activity and β-lactam resistance among E. coli populations can inform decisions on safety of irrigation water sources and One Health. IMPORTANCE Extended spectrum β-lactamase (ESBL) producing bacteria, that are resistant to a broad range of antimicrobial agents, are spreading in the environment but data remain scarce. ESBL-producing Escherichia coli infections in the community are on the rise. This work was conducted to assess presence of ESBL-producing E. coli in water that could be used for irrigation of fresh produce. The study provides the most extensive evaluation of ESBL-producing E. coli in surface and reclaimed water in the mid-Atlantic United States. The prevalence of ESBL producers was low and phenotypic resistance to cephalosporins (types of β-lactam antibiotics) was affected by season but not water type. Data on antimicrobial resistance among E. coli populations in water can inform decisions on safety of irrigation water sources and One Health.

Three strategies of transgenic manipulation for crop improvement

Heterologous expression of exogenous genes, overexpression of endogenous genes, and suppressed expression of undesirable genes are the three strategies of transgenic manipulation for crop improvement. Up to 2020, most (227) of the singular transgenic events (265) of crops approved for commercial release worldwide have been developed by the first strategy. Thirty-eight of them have been transformed by synthetic sequences transcribing antisense or double-stranded RNAs and three by mutated copies for suppressed expression of undesirable genes (the third strategy). By the first and the third strategies, hundreds of transgenic events and thousands of varieties with significant improvement of resistance to herbicides and pesticides, as well as nutritional quality, have been developed and approved for commercial release. Their application has significantly decreased the use of synthetic pesticides and the cost of crop production and increased the yield of crops and the benefits to farmers. However, almost all the events overexpressing endogenous genes remain at the testing stage, except one for fertility restoration and another for pyramiding herbicide tolerance. The novel functions conferred by the heterologously expressing exogenous genes under the control of constitutive promoters are usually absent in the recipient crops themselves or perform in different pathways. However, the endogenous proteins encoded by the overexpressing endogenous genes are regulated in complex networks with functionally redundant and replaceable pathways and are difficult to confer the desirable phenotypes significantly. It is concluded that heterologous expression of exogenous genes and suppressed expression by RNA interference and clustered regularly interspaced short palindromic repeats-cas (CRISPR/Cas) of undesirable genes are superior to the overexpression of endogenous genes for transgenic improvement of crops.

Effects of season and water type on the distribution and antimicrobial resistance of Enterococcus faecalis and E. faecium from surface and reclaimed water

AIMS

To evaluate the safety of irrigation water sources based on phenotypic antimicrobial resistance (AMR) in Enterococcus spp., a potential environmental reservoir for AMR determinants.

METHODS AND RESULTS

Eleven sites representing fresh and brackish water rivers, ponds and reclaimed water, were sampled over two years. Samples (n=333) yielded 198 unique isolates of E. faecalis and E. faecium which were tested for antimicrobial susceptibility by microbroth dilution. Species distribution was influenced by water type and season. E. faecalis was more likely found in freshwater rivers and in summer, and E. faecium in reclaimed water and in spring. Only 11% of isolates were pansusceptible, while 48.5% and 26.3% were single (SDR) and multidrug resistant (MDR), respectively. MDR was more likely detected in E. faecium than E. faecalis. Winter isolates were more likely than summer isolates to exhibit MDR than SDR.

CONCLUSIONS

E. faecalis and E. faecium in surface and reclaimed water exhibited diverse phenotypic AMR and a low-level resistance to clinically important antimicrobials such as ampicillin, vancomycin and linezolid.

SIGNIFICANCE AND IMPACT OF THE STUDY

Single and multidrug resistance in E. faecalis and E. faecium varied by season but not water type. AMR prevalence can assist decisions on the safety of irrigation water sources for fresh produce crops.

Impact of irrigation water type and sampling frequency on Microbial Water Quality Profiles required for compliance with U.S. Food Safety Modernization Act Produce Safety Rule standards

The U.S. Food Safety Modernization Act (FSMA) Produce Safety Rule (PSR) requires that farmers generate a Microbial Water Quality Profile (MWQP) from 20 samples per agricultural water source, taken over 2-4 years and five annual samples thereafter. Farmers must use the MWQP to ascertain a geometric mean (GM) of ≤126 CFU/100 mL and statistical threshold value (STV) of ≤410 CFU/100 mL of generic Escherichia coli. Farmers are responsible for collecting samples and paying for testing, incurring a financial and time burden. To determine if testing frequency can be reduced without compromising accuracy, water samples (n = 279) were collected from twelve sites in the U.S. Mid-Atlantic region from 2016 to 2018 comprising tidal brackish river, non-tidal fresh river, pond, vegetable processing, and reclaimed water. The GM and STV were calculated for all sites and water types using all samples, and for multiple sub-samples of <20 from each site and water type. A Monte Carlo simulation was used to determine the proportion of sub-sample sizes that yielded the same determination as the entire sample size of PSR standard compliance. Four sites, two pond and two reclaimed water sites, complied with PSR GM and STV requirements when using the entire sample set. When a water source's calculated GM and STV using the entire sample set hovered close to the PSR thresholds, sub-sample sizes approached the recommended 20 samples to reach a congruent compliance determination. However, 99% agreement was obtained with a sub-sample of five when the absolute difference between the GM and STV from total samples and the PSR thresholds was ≥2.6 and 4.5 log CFU/100 mL E. coli, respectively. These findings suggest that under certain conditions the MWQP may be generated with well below 20 samples, reducing the economic burden on farmers while still maintaining a representative MWQP.

A Literature Review of Wetland Treatment Systems Used to Treat Runoff Mixtures Containing Antibiotics and Pesticides from Urban and Agricultural Landscapes

Wetland treatment systems are used extensively across the world to mitigate surface runoff. While wetland treatment for nitrogen mitigation has been comprehensively reviewed, the implications of common-use pesticides and antibiotics on nitrogen reduction remain relatively unreviewed. Therefore, this review seeks to comprehensively assess the removal of commonly used pesticides and antibiotics and their implications for nitrogen removal in wetland treatment systems receiving non-point source runoff from urban and agricultural landscapes. A total of 181 primary studies were identified spanning 37 countries. Most of the reviewed publications studied pesticides (n = 153) entering wetlands systems, while antibiotics (n = 29) had fewer publications. Even fewer publications reviewed the impact of influent mixtures on nitrogen removal processes in wetlands (n = 16). Removal efficiencies for antibiotics (35–100%), pesticides (−619–100%), and nitrate-nitrogen (−113–100%) varied widely across the studies, with pesticides and antibiotics impacting microbial communities, the presence and type of vegetation, timing, and hydrology in wetland ecosystems. However, implications for the nitrogen cycle were dependent on the specific emerging contaminant present. A significant knowledge gap remains in how wetland treatment systems are used to treat non-point source mixtures that contain nutrients, pesticides, and antibiotics, resulting in an unknown regarding nitrogen removal efficiency as runoff contaminant mixtures evolve.

Impact of high precipitation and temperature events on the distribution of emerging contaminants in surface water in the Mid-Atlantic, United States

Extreme weather events induced by climate change have potential to impact water quality and have received increasing attention from surface water source management perspectives. However, it remains unclear how such phenomenon may influence concentration of emerging contaminants (ECs) in surface water that are vital source of irrigation. In the present study, we investigated the impact of high precipitation and ambient temperature on the distribution of ECs in surface water samples (N = 250) from Mid-Atlantic region, collected between 2016 and 2018. We analyzed the water samples using a liquid chromatography tandem mass spectrometry (LC-MS/MS) based method. We then investigated how the detection frequencies and concentrations of ten emerging contaminants were influenced by high precipitation and temperature events in the previous day or 7 days prior to the sampling events using a generalized additive model (GAM). We observed that heavy rainfalls occurring within 24 h before sampling increased the concentration/likelihood of detection of the ECs in surface waters, likely due to surface runoffs, remobilization from soil/sediment and sewage overflows. The impact of high precipitation during previous seven days varied across chemicals. Likewise, the detection frequency and concentration of most analytes increased with increasing temperature, in previous day of sampling event, likely due to enhanced solubility in water. Long-term high temperature events appeared to decrease the detection of the most tested ECs probably due to enhanced degradation. However, the potential risk of unknown degradation products cannot be ignored. Our results indicate potential decline of water quality after extreme weather events which may have implications for water source management under changing climate.

Magnetic particles encoding a suspension probe for ultra-sensitive and quantitative determination of atrazine

As a highly toxic and widely used herbicide, atrazine poses a serious threat to food safety as well as overall environmental and human health. Due to complex matrix interference and the difficulty of signal enrichment, there is an urgent need for a convenient, fast, and ultrasensitive method that detects trace atrazine without concern for matrix effects. Here, we provide the first account of a sensitive and rapid suspension probe based on magnetic microspheres used to detect atrazine in herbs. The self-made magnetic beads featured -COOH groups and were used as the carrier to construct immunofluorescent probes. These probes then conjugated with the atrazine antigen through an activated ester method, ultimately binding to the antibody. Homogeneous detection was ensured using flow cytometry and the microflow optical channel along with allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb) as the fluorescent signal. The magnetic suspension probe allowed for high target enrichment and the inherent two-dimensional selective detection of flow cytometry effectively avoided any matrix interference. This method had good linearity across 1.69-23.19 ng mL^-1. The IC₅₀ and LOD values were 4.81 ng mL^-1 and 0.95 ng mL^-1, respectively; the sensitivity was increased three-fold relative to ELISA. After complete optimization, 2-N-morpholinoeth-anesulfonic acid was used as the coupling solution and maintained good mono-dispersity, stability, and reactivity for the labelled microspheres during the process. The entire experiment was simple, and effectively used reagents; moreover, both the labor required and detection time were greatly reduced. Critically, the strategy presented here greatly reduced interference from complex matrices, and saved preparation for matrix-matched solutions when different herbs were screened. Overall, this strategy was sensitive, rapid, eco-friendly, and labor-saving; collectively, these attributes make it well-suited for on-site screening of atrazine contamination and will allow for increased food safety.

Synergistic effects of unsaturated flow and soil organic matter on retention and transport of PPCPs in soils

This study examines the effects of soil organic matter (SOM) and water content on the transport of five selected pharmaceutical and personal care products (PPCPs, ibuprofen, carbamazepine, bisphenol A, tetracycline, and ciprofloxacin) in four natural soils with different SOM contents. Batch isotherm experiment results showed that SOM effect was very significant for positively charged tetracycline and ciprofloxacin (>99% adsorption, no desorption), relatively significant for non-dissociated carbamazepine and bisphenol A (17-57% adsorption, 6-71% desorption) and insignificant for negatively charged ibuprofen (4-8% adsorption, 60-87% desorption) in the soils. Transport results showed that neither tetracycline nor ciprofloxacin moved through the saturated and unsaturated soil columns, demonstrating their very limited mobility in soils as a result of significant electrostatic attraction independent of SOM and water conditions. Overall, higher SOM content and lower water content were favorable to the retention of ibuprofen, carbamazepine and bisphenol A in the soils. Breakthrough of ibuprofen, carbamazepine and bisphenol A was 100% (both saturated and unsaturated), 94% (saturated)-97% (unsaturated) and 85% (saturated)-90% (unsaturated) in SOM-removed soils; however only 78% (saturated)-57% (unsaturated), 93% (saturated)-67% (unsaturated), 11% (saturated)-0% (unsaturated) in the SOM-high soils. The effect of water content was not significant in the SOM-removed soils. The SOM could increase the kinetic (type 2) adsorption of PPCPs at the solid-water interface (SWI), and the air phase could increase the instantaneous (type 1) adsorption of PPCPs at the air-water interface (AWI). This result suggests that lowering water content could greatly enhance the adsorption of PPCPs that had high affinities to soils and vice versa. This study provides an important implication that AWI and SWI might have a nonlinear relationship in promoting the adsorption and reducing the mobility of PPCPs under unsaturated flow conditions.

Caffeine removal by Gliricidia sepium biochar: Influence of pyrolysis temperature and physicochemical properties

The present study aimed to envisage the effect of physicochemical properties on the performance of Gliricidia sepium biochar (GBC) pyrolyzed at 300, 500, and 700 °C in the removal caffeine (CFN); a pharmaceutical and personal care product, from water. The physicochemical properties of GBC were characterized by proximate and ultimate analysis, BET, SEM, FTIR, and Raman spectroscopy. The adsorption batch experiment was carried out at various pH values (pH 3-10), mixing times (up to 24 h), and initial CFN concentration (10-500 mg/L). The FTIR analysis revealed the loss of polar functional groups on the surface of GBC derived at high temperatures. The red-shifted and blue-shifted Raman peaks indicate the condensation of small molecules on GBC. The GBC derived at 700 °C demonstrated high CFN adsorption capacity (16.26 mg/g) due to its high surface area and aromaticity. The highest adsorption of CFN was occurred at acidic pH range from 3.5 to 4.5 due to the existence of non-specific attraction between CFN and GBC. The kinetics and isotherm experimental data were fitted with Elovich and fractional power kinetic regression, Freundlich, and Temkin isotherm models, which suggested the adsorption of CFN on the GBC by mixed mechanisms; physisorption and chemisorption including π-π interactions, hydrogen bonding, n-π interactions, electrostatic attraction, and electron donor-acceptor attraction. Moreover, both surface area and aromaticity index have demonstrated a high positive correlation for CFN adsorption, signifying the importance of controlling physicochemical properties based on the end-user purpose of biochar.

Longitudinal Assessment of the Dynamics of Escherichia coli, Total Coliforms, Enterococcus spp., and Aeromonas spp. in Alternative Irrigation Water Sources: a CONSERVE Study

As climate change continues to stress freshwater resources, we have a pressing need to identify alternative (nontraditional) sources of microbially safe water for irrigation of fresh produce. This study is part of the center CONSERVE, which aims to facilitate the adoption of adequate agricultural water sources. A 26-month longitudinal study was conducted at 11 sites to assess the prevalence of bacteria indicating water quality, fecal contamination, and crop contamination risk (Escherichia coli, total coliforms [TC], Enterococcus, and Aeromonas). Sites included nontidal freshwater rivers/creeks (NF), a tidal brackish river (TB), irrigation ponds (PW), and reclaimed water sites (RW). Water samples were filtered for bacterial quantification. E. coli, TC, enterococci (∼86%, 98%, and 90% positive, respectively; n = 333), and Aeromonas (∼98% positive; n = 133) were widespread in water samples tested. Highest E. coli counts were in rivers, TC counts in TB, and enterococci in rivers and ponds (P < 0.001 in all cases) compared to other water types. Aeromonas counts were consistent across sites. Seasonal dynamics were detected in NF and PW samples only. E. coli counts were higher in the vegetable crop-growing (May-October) than nongrowing (November-April) season in all water types (P < 0.05). Only one RW and both PW sites met the U.S. Food Safety Modernization Act water standards. However, implementation of recommended mitigation measures of allowing time for microbial die-off between irrigation and harvest would bring all other sites into compliance within 2 days. This study provides comprehensive microbial data on alternative irrigation water and serves as an important resource for food safety planning and policy setting.IMPORTANCE Increasing demands for fresh fruit and vegetables, a variable climate affecting agricultural water availability, and microbial food safety goals are pressing the need to identify new, safe, alternative sources of irrigation water. Our study generated microbial data collected over a 2-year period from potential sources of irrigation (rivers, ponds, and reclaimed water sites). Pond water was found to comply with Food Safety Modernization Act (FSMA) microbial standards for irrigation of fruit and vegetables. Bacterial counts in reclaimed water, a resource that is not universally allowed on fresh produce in the United States, generally met microbial standards or needed minimal mitigation. We detected the most seasonality and the highest microbial loads in river water, which emerged as the water type that would require the most mitigation to be compliant with established FSMA standards. This data set represents one of the most comprehensive, longitudinal analyses of alternative irrigation water sources in the United States.

Responsible Water Reuse Needs an Interdisciplinary Approach to Balance Risks and Benefits

Freshwater is a precious resource, and shortages can lead to water stress, impacting agriculture, industry, and other sectors. Wastewater reuse is increasingly considered as an opportunity to meet the freshwater demand. Legislative frameworks are under development to support the responsible reuse of wastewater, i.e., to balance benefits and risks. In an evaluation of the proposed European regulation for water reuse, we concluded that the proposed regulation is not practically feasible, as the water provider alone is responsible for the risk assessment and management, even beyond their span of control. The required knowledge and resources are extensive. Therefore, without clear guidance for implementation, the regulation would hinder implementation of reuse programs. As a consequence, the current practice of uncontrolled, unintentional, and indirect reuse continues, including related risks and inefficiency. Therefore, we provide an outline of the interdisciplinary approach required to design and achieve safe, responsible water reuse. Responsible water reuse requires knowledge of water demand and availability, quality and health, technology, and governance for the various types of application. Through this paper we want to provide a starting point for an interdisciplinary agenda to compile and generate knowledge (databases), approaches, guidelines, case examples, codes of practice, and legislation to help bring responsible water reuse into practice.

Antibiotic and herbicide concentrations in household greywater reuse systems and pond water used for food crop irrigation: West Bank, Palestinian Territories

Greywater is increasingly treated and reused for agricultural irrigation in off-grid communities in the Middle East and other water scarce regions of the world. However, there is a dearth of data regarding levels of antibiotics and herbicides in off-grid greywater treatment systems. To address this knowledge gap, we evaluated levels of these contaminants in two types of greywater treatment systems on four farms in the West Bank, Palestinian Territories. Samples of household greywater (influent, n = 23), treated greywater effluent intended for agricultural irrigation (n = 23) and pumped groundwater held in irrigation water ponds (n = 12) were collected from October 2017 to June 2018. Samples were analyzed using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) for the following antibiotics and herbicides: alachlor, ampicillin, atrazine, azithromycin, ciprofloxacin, erythromycin, linezolid, oxacillin, oxolinic acid, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, tetracycline, triflualin, and vancomycin. All tested antibiotics and herbicides were detected in greywater influent samples at concentrations ranging from 1.3 to 1592.9 ng/L and 3.1-22.4 ng/L, respectively. When comparing influent to effluent concentrations, removal was observed for azithromycin, alachlor, linezolid, oxacillin, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, and vancomycin. Removal was not observed for atrazine, ciprofloxacin, erythromycin, oxolinic acid, tetracycline, and trifluralin. Pond water also contained the majority of tested contaminants, but at generally lower concentrations. To our knowledge, this is the first description of an extensive array of antibiotics and herbicides detected in household greywater from off-grid treatment systems.