Fates and transport of PPCPs in soil receiving reclaimed water irrigation

Uptake and translocation of pharmaceutically active compounds by olive tree (Olea europaea L.) irrigated with treated municipal wastewater

Introduction

The use of treated municipal wastewater (TWW) represents a relevant opportunity for irrigation of agricultural crops in semi-arid regions to counter the increasing water scarcity. Pharmaceutically active compounds (PhACs) are often detected in treated wastewater, posing a risk to humans and the environment. PhACs can accumulate in soils and translocate into different plant tissues, reaching, in some cases, edible organs and entering the food chain.

Methods

This study evaluated the uptake and translocation processes of 10 PhACs by olive trees irrigated with TWW, investigating their accumulation in different plant organs. The experiment was conducted in southern Italy, in 2-year-old plants irrigated with three different types of water: freshwater (FW), TWW spiked with 10 PhACs at a concentration of 200 µg L-1 (1× TWW), and at a triple dose (3× TWW), from July to October 2021. The concentration of PhACs in soil and plant organs was assessed, collecting samples of root, stem, shoot, leaf, fruit, and kernel at 0 (T0), 50 (T1), and 107 (T2) days of irrigation. PhACs extraction from soil and plant organs was carried out using the QuEChERS method, and their concentrations were determined by high-resolution mass spectrometry coupled with liquid chromatography.

Results

Results of uptake factors (UF) showed a different behavior between compounds according to their physicochemical properties, highlighting PhACs accumulation and translocation in different plant organs (also edible part) in 1× TWW and 3× TWW compared to FW. Two PhACs, carbamazepine and fluconazole, showed interactions with the soil-plant system, translocating also in the aerial part of the plant, with a translocation factor (TF) greater than 1, which indicates high root-to-leaf translocation.

Discussion

Findings highlight that only few PhACs among the selected compounds can be uptaken by woody plants and accumulated in edible parts at low concentration. No effects of PhACs exposure on plant growth have been detected. Despite the attention to be paid to the few compounds that translocate into edible organs, these results are promising for adapting wastewater irrigation in crops. Increasing knowledge about PhACs behavior in woody plants can be important for developing optimized wastewater irrigation and soil management strategies to reduce PhACs accumulation and translocation in plants.

Emerging organic contaminants in the soil-plant-receptor continuum: transport, fate, health risks, and removal mechanisms

There is a lack of comprehensive reviews tracking emerging organic contaminants (EOCs) within the soil-plant continuum using the source-pathway-receptor-impact-mitigation (SPRIM) framework. Therefore, this review examines existing literature to gain insights into the occurrence, behaviour, fate, health hazards, and strategies for mitigating EOCs within the soil-plant system. EOCs identified in the soil-plant system encompass endocrine-disrupting chemicals, surfactants, pharmaceuticals, personal care products, plasticizers, gasoline additives, flame retardants, and per- and poly-fluoroalkyl substances (PFAS). Sources of EOCs in the soil-plant system include the land application of biosolids, wastewater, and solid wastes rich in EOCs. However, less-studied sources encompass plastics and atmospheric deposition. EOCs are transported from their sources to the soil-plant system and other receptors through human activities, wind-driven processes, and hydrological pathways. The behaviour, persistence, and fate of EOCs within the soil-plant system are discussed, including sorption, degradation, phase partitioning, (bio)transformation, biouptake, translocation, and bioaccumulation in plants. Factors governing the behaviour, persistence, and fate of EOCs in the soil-plant system include pH, redox potential, texture, temperature, and soil organic matter content. The review also discusses the environmental receptors of EOCs, including their exchange with other environmental compartments (aquatic and atmospheric), and interactions with soil organisms. The ecological health risks, human exposure via inhalation of particulate matter and consumption of contaminated food, and hazards associated with various EOCs in the soil-plant system are discussed. Various mitigation measures including removal technologies of EOCs in the soil are discussed. Finally, future research directions are presented.

Tracing COVID-19 drugs in the environment: Are we focusing on the right environmental compartment?

The Coronavirus Disease 2019 (COVID-19) pandemic led to over 770 million confirmed cases, straining public healthcare systems and necessitating extensive and prolonged use of synthetic chemical drugs around the globe for medical treatment and symptom relief. Concerns have arisen regarding the massive release of active pharmaceutical ingredients (APIs) and their metabolites into the environment, particularly through domestic sewage. While discussions surrounding this issue have primarily centered on their discharge into aquatic environments, particularly through treated effluent from municipal wastewater treatment plants (WWTPs), one often overlooked aspect is the terrestrial environment as a significant receptor of pharmaceutical-laden waste. This occurs through the disposal of sewage sludge, for instance, by applying biosolids to land or non-compliant disposal of sewage sludge, in addition to the routine disposal of expired and unused medications in municipal solid wastes. In this article, we surveyed sixteen approved pharmaceuticals for treating COVID-19 and bacterial co-infections, along with their primary metabolites. For this, we delved into their physiochemical properties, ecological toxicities, environmental persistence, and fate within municipal WWTPs. Emphasis was given on lipophilic substances with log Kow >3.0, which are more likely to be found in sewage sludge at significant factions (25.2%-75.0%) of their inputs in raw sewage and subsequently enter the terrestrial environment through land application of biosolids, e.g., 43% in the United States and as high as 96% in Ireland or non-compliant practices of sewage sludge disposal in developing communities, such as open dumping and land application without prior anaerobic digestion. The available evidence underscores the importance of adequately treating and disposing of sewage sludge before its final disposal or land application in an epidemic or pandemic scenario, as mismanaged sewage sludge could be a significant vector for releasing pharmaceutical compounds and their metabolites into the terrestrial environment.

Mobility of antipyretic drugs with different molecular structures in saturated soil porous media

In the post-COVID-19 era, extensive quantities of antipyretic drugs are being haphazardly released from households into the environment, which may pose potential risks to ecological systems and human health. Identification of the mobility behaviors of these compounds in the subsurface environment is crucial to understand the environmental fate of these common contaminants. The mobility properties of three broad-spectrum antipyretic drugs, including ibuprofen (IBF), indometacin (IMC), and acetaminophen (APAP), in porous soil media, were investigated in this study. The results showed that the mobility of the three drugs (the background electrolyte was Na+) through the soil column followed the order of APAP > IBF > IMC. The difference in the physicochemical characteristics of various antipyretic drugs (e.g., the molecular structure and hydrophobicity) could explain this trend. Unlike Na+, Ca2+ ions tended to serve as bridging agents by linking the soil grains and antipyretic molecules, leading to the relatively weak mobility behaviors of antipyretic drugs. Furthermore, for a given antipyretic drug, the antipyretic mobility was promoted when the background solution pH values were raised from 5.0 to 9.0. The phenomenon stemmed from the improved electrostatic repulsion between the dissociated species of antipyretic molecules and soil grains, as well as the weakened hydrophobic interactions between antipyretic drugs and soil organic matter. Furthermore, a two-site non-equilibrium transport model was used to estimate the mobility of antipyretic drugs. The results obtained from this work provide vital information illustrating the transport and retention of various antipyretic drugs in aquifers.

Emerging environmental health risks associated with the land application of biosolids: a scoping review

BACKGROUND

Over 40% of the six million dry metric tons of sewage sludge, often referred to as biosolids, produced annually in the United States is land applied. Biosolids serve as a sink for emerging pollutants which can be toxic and persist in the environment, yet their fate after land application and their impacts on human health have not been well studied. These gaps in our understanding are exacerbated by the absence of systematic monitoring programs and defined standards for human health protection.

METHODS

The purpose of this paper is to call critical attention to the knowledge gaps that currently exist regarding emerging pollutants in biosolids and to underscore the need for evidence-based testing standards and regulatory frameworks for human health protection when biosolids are land applied. A scoping review methodology was used to identify research conducted within the last decade, current regulatory standards, and government publications regarding emerging pollutants in land applied biosolids.

RESULTS

Current research indicates that persistent organic compounds, or emerging pollutants, found in pharmaceuticals and personal care products, microplastics, and per- and polyfluoroalkyl substances (PFAS) have the potential to contaminate ground and surface water, and the uptake of these substances from soil amended by the land application of biosolids can result in contamination of food sources. Advanced technologies to remove these contaminants from wastewater treatment plant influent, effluent, and biosolids destined for land application along with tools to detect and quantify emerging pollutants are critical for human health protection.

CONCLUSIONS

To address these current risks, there needs to be a significant investment in ongoing research and infrastructure support for advancements in wastewater treatment; expanded manufacture and use of sustainable products; increased public communication of the risks associated with overuse of pharmaceuticals and plastics; and development and implementation of regulations that are protective of health and the environment.

Ecological risks induced by consumption and emission of Pharmaceutical and personal care products in Qinghai-Tibet Plateau: Insights from the polar regions

As the third pole of the world and Asia's water tower, the Tibetan Plateau experiences daily release of pharmaceutical and personal care products (PPCPs) due to increasing human activity. This study aimed to explore the potential relationship between the concentration and composition of PPCPs and human activity, by assessing the occurrence of PPCPs in areas of typical human activity on the Qinghai-Tibet Plateau and evaluating their ecological risk. The results indicate that 28 out of 30 substances were detected in concentrations ranging from less than 1 ng/L to hundreds of ng/L, with the average concentration of most PPCPs in the Tibet Autonomous Region being higher than that in Qinghai Province. Among the detected substances, CAF, NOR, CTC, CIP, TCN, OTC, AZN, and DOX accounted for over 90% of the total concentration. The emission sources of PPCPs were identified by analyzing the correlation coefficients of soil and water samples, with excess PPCPs used by livestock breeding discharged directly into soil and then into surface water through leaching or runoff. By comparing the concentration and composition of PPCPs with those in other regions, this study found that CIP, ENR, LOM, NOR, CTC, DOX, OTC, and TCN were the most commonly used PPCPs in the Qinghai-Tibet Plateau. To assess the ecological risk of PPCPs, organisms at different trophic levels, including algae, crustaceans, fish, and insects, were selected. The prediction of the no effect concentration of each PPCP showed that NOR, CTC, TCN, CAF, and CBZ may have deleterious effects on water biota. This study can assist in identifying the emission characteristics of PPCPs from different types and intensities of human activities, as well as their occurrence and fate during the natural decay of aquatic systems.

Multimedia fate of sulfamethoxazole (SMX) in a water-scarce city by coupling fugacity model and HYDRUS-1D model

Increased concentrations of pharmaceutical and personal care products (PPCPs) have raised concerns about their impact on the ecological system and human health. To understand the environmental impact of PPCPs, we evaluated the fate of a typical PPCP of sulfamethoxazole (SMX) in a water-scarce city of Tianjin during 2013-2020 using a coupled model based on the dynamic fugacity model and HYDRUS-1D model. The results showed that the coupled model successfully simulated the reported SMX concentrations in the main fate media of water and soils, which accounted for 46.4 % and 53.0 % with equilibrium concentrations of 135-165 ng/L and 0.4-0.5 ng/g, respectively. The cross-media transfer flux results showed that advection was the prime input path for SMX in water, while degradation was the dominant output path. Wastewater irrigation and degradation were the main transfer processes of SMX in the soil. Moreover, human activities (i.e., emission loads) and climate (i.e., temperature and precipitation) change can significantly affect the concentrations and transfer rate of SMX in the media. These findings provide basic data and methods for the risk assessment of SMX in water-scarce regions.

Advancements in the dominion of fate and transport of pharmaceuticals and personal care products in the environment-a bibliometric study

The study on the fate and transport of Pharmaceuticals and Personal Care Products, PPCPs (FTP) in the environment, has received particular attention for over two decades. The PPCPs threaten ecology and human health even at low concentrations due to their synergistic effects and long-range transport. The research aims to provide an inclusive map of the scientific background of FTP research over the last 25 years, from 1996 to 2020, to identify the main characteristics, evolution, salient research themes, trends, and research hotspots in the field of interest. Bibliometric networks were synthesized and analyzed for 577 journal articles extracted from the Scopus database. Consequently, seven major themes of FTP research were identified as follows: (i) PPCPs category; (ii) hazardous effects; (iii) occurrence of PPCPs; (iv) PPCPs in organisms; (v) remediation; (vi) FTP-governing processes; and (vii) assessment in the environment. The themes gave an in-depth picture of the sources of PPCPs and their transport and fate processes in the environment, which originated from sewage treatment plants and transported further to sediment/soils/groundwater/oceans that act as the PPCPs' major sink. The article provided a rigorous analysis of the research landscape in the FTP study conducted during the specified years. The prominent research themes, content analysis, and research hotspots identified in the study may serve as the basis of real-time guidance to lead future research areas and a prior review for policymakers and practitioners.

Modeling the fate of ionizable pharmaceutical and personal care products (iPPCPs) in soil-plant systems: pH and speciation

A model was developed to simulate the pH-dependent speciation and fate of ionizable pharmaceutical and personal care products (iPPCPs) in soils and their plant uptake during thedt application of reclaimed wastewater to agricultural soils. The simulation showed that pH plays an important role in regulating the plant uptake of iPPCPs, i.e., ibuprofen (IBU; with a carboxylic group), triclosan (TCS; phenolic group), and fluoxetine (FXT; amine group) as model compounds. It took 89-487 days for various iPPCPs to reach the steady-state concentrations in soil and plant tissues. The simulated steady-state concentrations of iPPCPs in plant tissues at pH 9 is 2.2-2.3, 2.5-2.6, and 1.07-1.08 times that at pH 5 for IBU, TCS, and FXT, respectively. Assuming sorption only for neutral compounds led to miscalculation of iPPCPs concentrations in plant tissues by up to one and half orders magnitude. Efflux of compounds in soil, lettuce leaf, and soybean pods was primarily contributed by their degradation in soil and dilution due to plant tissue growth. Overall, the results demonstrated the importance of considering pH and speciation of iPPCPs when simulating their fate in the soil-plant system and plant uptake.

Characteristics of dissolved organic matter in two alternative water sources: A comparative study between reclaimed water and stormwater

Reclaimed water and stormwater are two important alternative water sources to mitigate water resource shortage. They can be reused by discharging into drinking water sources. Due to different sources, characteristics of dissolved organic matter (DOM, a precursor of disinfection by-products, DBPs) present in reclaimed water and stormwater would be different. This study selected reclaimed water to compare with stormwater (including both stormwater runoff and rainwater) by investigating their DOM characteristics, including concentrations, aromaticity, molecular weight, hydrophobicity/hydrophilicity, composition and DBPs formation potential. The results showed that reclaimed water had higher dissolved organic carbon (DOC) concentrations (6.02-10.8 mg/L) than stormwater (3.62-5.48 mg/L) while SUVA₂₅₄ values of stormwater runoff (1.92-2.53 L/(mg-C·m)) were higher than reclaimed water (1.11-1.24 L/(mg-C·m)). Additionally, reclaimed water is more hydrophobic while stormwater runoff and rainwater are more hydrophilic. Although all water types included the highest fraction of DOM with molecular weight <1 kDa (43.0 %-77.5 %), reclaimed water primarily contained soluble microbial products (SMPs)-like and humic acid-like substances while stormwater runoff primarily contained humic acid-like DOM. In terms of DBPs, reclaimed water showed relatively higher formation potential than stormwater runoff while rainwater had the lowest DBPs formation potential. These results can contribute to effective water resource management. Particularly, when reclaimed water or/and stormwater are discharged into drinking water sources, these outcomes can help on efficient drinking water treatment.

Contaminants of emerging concerns in recycled water: Fate and risks in agroecosystems

Recycled water (RW) has been increasingly recognized as a valuable source of water for alleviating the global water crisis. When RW is used for agricultural irrigation, many contaminants of emerging concern (CECs) are introduced into the agroecosystem. The ubiquity of CECs in field soil, combined with the toxic, carcinogenic, or endocrine-disrupting nature of some CECs, raises significant concerns over their potential risks to the environment and human health. Understanding such risks and delineating the fate processes of CECs in the water-soil-plant continuum contributes to the safe reuse of RW in agriculture. This review summarizes recent findings and provides an overview of CECs in the water-soil-plant continuum, including their occurrence in RW and irrigated soil, fate processes in agricultural soil, offsite transport including runoff and leaching, and plant uptake, metabolism, and accumulation. The potential ecological and human health risks of CECs are also discussed. Studies to date have shown limited accumulation of CECs in irrigated soils and plants, which may be attributed to multiple attenuation processes in the rhizosphere and plant, suggesting minimal health risks from RW-fed food crops. However, our collective understanding of CECs is rather limited and knowledge of their offsite movement and plant accumulation is particularly scarce for field conditions. Given a large number of CECs and their occurrence at trace levels, it is urgent to develop strategies to prioritize CECs so that future research efforts are focused on CECs with elevated risks for offsite contamination or plant accumulation. Irrigating specific crops such as feed crops and fruit trees may be a viable option to further minimize potential plant accumulation under field conditions. To promote the beneficial reuse of RW in agriculture, it is essential to understand the human health and ecological risks imposed by CEC mixtures and metabolites.

Adsorption and desorption of antiviral drugs (ritonavir and lopinavir) on sewage sludges as a potential environmental risk

The aim of this work was to evaluate the adsorption capacity and mechanism of two antiviral drugs AVDs (lopinavir (LOP) and ritonavir (RIT)) on three various sewage sludges (SSLs). The results showed that SSLs differed in the structure and chemical composition and LOP and RIT had a high affinity to the studied SSLs (K_d in ranges 2076-3449 L/kg). The adsorption capacities differed between SSLs and ranged 7.55-8.71 mg/g (RIT) and 8.10-8.64 mg/g (LOP). The Freundlich model provided a best fitting of adsorption isotherms of all AVDs-SSLs. The adsorption kinetics were best described by pseudo-second order kinetic model. The adsorption of LOP and RIT on SSLs was exothermic, spontaneous, and thermodynamically feasible. The sorption of LOP and RIT to SSLs was complex due to the diverse chemical composition of SSLs and the differences in the chemical structure of AVDs. Analysis of binary solution of both AVDs showed the competition effect between AVDs and a decrease in adsorption efficiency (3-17%) compared to single solutions. The amount of desorbed AVDs from all SSLs was low (less than 15%). The findings of the present work are significant in the prediction of fate and persistence of AVDs on SSLs in the context of their further transmission and possible environmental contamination.

Heat-activated peracetic acid for degradation of diclofenac: kinetics, influencing factors and mechanism

ABSTRACTHeat-activated peracetic acid (PAA) was used to degrade diclofenac (DCF) in this study. Electron paramagnetic resonance and radical scavenging experiments proved that organic radicals (i.e. CH₃C(=O)O• and CH₃C(=O)OO•) were the primary active species for DCF removal in the heat/PAA process. The degradation efficiency of DCF increased with the increase of temperature or initial PAA concentration in the heat/PAA process, and the optimal reaction pH for DCF removal was neutral. The presence of NO₃^- or SO₄^2- insignificantly affected DCF degradation, while Cl^- was favourable for DCF removal in this process. In contrast, an obvious inhibition on the removal of DCF was observed with the addition of natural organic matter, which might be responsible for the lower DCF removal in real waters. Finally, dechlorination, formylation, dehydrogenation and hydroxylation were proposed to be four degradation pathways of DCF in the heat/PAA system based on the five detected transformation products.

Fate of PAHs in treated wastewater reused as irrigation water: Environmental risks in water-soil-ryegrass multimedia system

The main aim of this study was to determine the fate, bio-metabolism and environmental risk of low-ring and high-ring polycyclic aromatic hydrocarbons (PAHs) in a water-soil-ryegrass multi-media system, under long-term irrigation condition with micro-polluted treated wastewater. Field experiments were carried out to simulate garden irrigation using treated wastewater containing typical representative low-ring naphthalene (Nap) and high-ring benzo[a]pyrene (BaP). The results showed that BaP's vertical attenuation rate and adsorption accumulation rate were 1.7 and 1.2 times higher than Nap's, respectively. The adsorption, biodegradation, and the rhizosphere effect were responsible for 40.7%, 28.4%, 21.6%, and 30.5%, 36.6%, 17.7%, respectively, of the attenuation of BaP and Nap. The major metabolic pathways of Nap and BaP are hydroxylation, ring opening cleavage, and decarboxylation, with the metabolic chain of BaP being longer than that of Nap due to more ring cleaving reactions. Pseudomonas, Mycobacterium, and Sphingomonas were the functional microorganisms with PAHs degradation capacity that were positively correlated with PAHs degradation, particularly in the rhizosphere. After ten years of irrigation with treated wastewater, the prediction of environmental risk revealed that there were few potential risks. Thus, the results of this feasibility study demonstrated that using treated wastewater for garden irrigation was a relatively safe and effective strategy.

Phosphate-induced activation of peracetic acid for diclofenac degradation: Kinetics, influence factors and mechanism

Activating peroxides to produce active substances is the key to advanced oxidation processes (AOPs), but this usually requires energy or is accompanied by additional contaminants. In this study, diclofenac (DCF) was effectively removed by peracetic acid (PAA) in phosphate buffer (PBS). According to the results of radical scavenging experiments and electron paramagnetic resonance (EPR), hydroxyl radical (•OH) and organic radicals (i.e., CH₃C(=O)OO• and CH₃C(=O)O•) generated from PBS-activated PAA might be the dominant reactive species responsible for DCF degradation. At neutral pH, PBS/PAA system exhibited the best degradation efficiency on DCF. Presence of NO₃^-, SO₄^2- and Cl^- had little effect on the removal of DCF, while HCO₃^- and natural organic matter (NOM) significantly inhibited DCF degradation in PBS/PAA system, resulting in the lower degradation efficiency of DCF in natural waters than that in ultrapure water. Finally, four possible degradation pathways, including hydroxylation, formylation, dehydrogenation and dechlorination, were proposed based on the detected reaction products. This study suggests that PBS used to control solution pH should be applied cautiously in PAA-based AOPs.

River water treatment using electrocoagulation for removal of acetaminophen and natural organic matter

Electrocoagulation (EC) was assessed for removal of acetaminophen and natural organic matter (measured as UV₂₅₄) from river water. Process was assessed for time, electrode materials, inter electrode distance, and voltage. Best conditions for removal of acetaminophen and UV₂₅₄ absorbance were 60 min reaction time, aluminum-aluminum electrodes, 2 cm inter electrode distance, and 9 V. Acetaminophen tested at 1, 2, 5, 10, and 20 mg L^-1 showed that treatment efficiency decreased as the concentration increased. The main mechanism for removal of acetaminophen was H bonding with Al(OH)₃ flocs; this was confirmed by XRD and FT-IR spectrum. Pseudo-second order kinetics model exhibited a good fit on experimental data for acetaminophen removal at different concentrations. Univariate ANOVA indicated statistically significant difference between treatments for acetaminophen removal (F_2.76 = 136, P = <0.001). A significant linear correlation was found between UV₂₅₄ absorbance and acetaminophen removal at different concentrations. Preliminary analysis suggest that EC will cost US$ 0.22/m³ for river water treatment. The lab-scale EC process was compared with a full-scale water treatment plant for removal of natural organic matter. Water treatment plant after multiple levels of purification was not able to fully remove UV₂₅₄ absorbance whereas EC treatment showed good efficiency.

The effect of PFOs on the uptake and translocation of emerging contaminants by crops cultivated under soil and soilless conditions

The Mediterranean is a region of substantial agriculture production that faces concurrent environmental stresses and freshwater pollution given the occurrence of emerging contaminants (ECs). Among these pollutants, the surface-active substances have been suggested to enhance the bioavailability of other ECs. This research evaluates a comparative uptake and translocation assessment of irrigation exposure to atenolol (ATN, 60 µg/L), carbamazepine (CBZ, 60 µg/L) and triclosan (TCS, 30 µg/L) alone vs. these combined with perfluorooctanesulfonic acid (PFOS, 10 µg/L) under semifield (i.e., soil experimental set) vs. hydroponics (i.e., soilless experimental set) growing conditions with lettuce, radish and tomato plants. Both experimental sets revealed efficient root uptake and translocation for the three ECs regardless of their co-existence with PFOS. The overall results of the uptake and translocation of the ECs in the lettuce and tomato plants suggested a simultaneous treatment-plant organ interaction, which was not affected by PFOS being present in both experimental sets. PFOS in irrigation water did not increase cellular perviousness to the other three ECs. These observations support the hypothesis of factors other than PFOS being responsible for the differential bioaccumulation and translocation potentials seen in both experimental sets. However, the radish plants co-irrigated with PFOS brought about increased movement of ECs from roots to aerial parts, more specifically ATN and CBZ in the soil experimental set, and ATN and TCS in the soilless set. These results support the notion that factors inherent to the physiological characteristics of this root vegetable contributed to ECs' increased tendency to move from roots to aerial parts. Despite the three ECs efficiently accumulating, the risk to humans from eating the edible parts of these plants grown under soil or soilless conditions was low.

Modeling the fate and human health impacts of pharmaceuticals and personal care products in reclaimed wastewater irrigation for agriculture

Wastewater reclamation and reuse for agriculture have attracted a great deal of interest, due to water stress caused by rapid increase in human population and agricultural water demand as well as climate change. However, the application of treated wastewater for irrigation can lead to the accumulation of pharmaceuticals and personal care products (PPCPs) in the agricultural crops, grazing animals, and consequently to human dietary exposure. In this study, a model was developed to simulate the fate of five PPCPs; triclosan (TCS), carbamazepine (CBZ), naproxen (NPX), gemfibrozil (GFB), and fluoxetine (FXT) during wastewater reuse for agriculture, and potential human dietary exposure and health risk. In a reclaimed wastewater-irrigated grazing farm growing alfalfa, it took 100-535 days for PPCPs to achieve the steady-state concentrations of 1.43 × 10^-6, 4.73 × 10^-5, 1.17 × 10^-6, 1.53 × 10^-5, and 7.38 × 10^-6 mg/kg for TCS, CBZ, NPX, GFB, and FXT in soils, respectively. The accumulated concentration of PPCPs in the plant (alfalfa) and grazing animals (beef) ranged 2.86 × 10^-7- 4.02 × 10^-3 and 4.39 × 10^-15- 6.27 × 10^-7 mg/kg, respectively. Human dietary exposure to these compounds through beef consumption was calculated to be 1.67 × 10^-18- 1.74 × 10^-10 mg/kg bodyweight/d, much lower than the acceptable daily intake (ADI). Similar results were obtained for a 'typical' reclaimed wastewater irrigated farm based on the typical setup using our model. Screening analysis showed that PPCPs with relatively high LogD value and lower ratios of degradation rate (in soils) to plant uptake have a greater potential to be transferred to humans and cause potential health risks. We established a modeling method for evaluating the fate and human health effects of PPCPs in reclaimed wastewater reuse for the agricultural system and developed an index for screening PPCPs with high potential to accumulate in agricultural products. The model and findings are valuable for managing water reuse for irrigation and mitigating the harmful effects of PPCPs.

Phenols in soils and agricultural products irrigated with reclaimed water

The presence of phenols, such as nonylphenol (NP), bisphenol (BPA), and octylphenol (OP), in the environment have been receiving increased attention due to their potential risks to human health and environment. The use of reclaimed water for irrigation may be one of the sources of these phenols in the agricultural system. A field experiment was conducted to assess the effects of reclaimed water irrigation on phenol contamination of agricultural topsoil and products in the North China Plain between 2015 and 2016. Three irrigation treatments were applied to all crops: reclaimed water irrigation, groundwater irrigation and alternative irrigation with reclaimed water and groundwater (1:1, v/v). The results showed that the concentrations of NP, BPA, and OP in the topsoil were 0.02-0.54, 0.004-0.06, and ND-9.9 × 10^-3 mg/kg, respectively; the corresponding values in agricultural products were 0.007-0.70, 0.004-0.24, and ND-1.08 mg/kg, respectively. The concentration of NP in the topsoil and agricultural products and that of BPA in the agricultural products were all less than the recommended limits. The yields of wheat, maize, vegetables were 4.35-7.08, 1.03-6.46, and 10.9-67.0 t/ha, respectively. The bioaccumulation factors (BCFs) of OP, NP, and BPA for cereals were 0.7-4.77, 0.16-4.59, and 1.3-23.9, respectively; the corresponding values in vegetables were 0.0-4.53 (except cucumber and eggplant), 0.38-12.6, and 0.57-24.3, respectively. No significant differences in phenol concentrations, BCFs, or yields of wheat and vegetables were observed among the three irrigation treatments. In conclusion, compared with groundwater irrigation, reclaimed water irrigation in this experiment did not significantly affect phenol concentrations in the topsoil and agricultural products as well as BCFs and yields of wheat and vegetables. However, because the quality of reclaimed water may vary across collected areas, additional experiments are warranted to analyze the effects of reclaimed water irrigation on the risk of phenol contamination.

Risk assessment and investigation of landfill leachate as a source of emerging organic contaminants to the surrounding environment: a case study of the largest landfill in Jinan City, China

Emerging organic contaminants (EOCs) have been widely studied in landfill leachates but not in the surrounding environment of landfills. In this study, two sampling campaigns were conducted to determine 45 EOCs in landfill leachates and environmental samples near a landfill in East China. Our study focused on the seasonal occurrence and spatial distribution of the target EOCs, as well as their ecological risks. The results showed 13 out of 45 EOCs were detectable and achieved individual concentrations that ranged from 2.0 to 5080 ng/L in the landfill leachates. Most of the detected EOCs exhibited higher concentrations in the leachates collected in summer than in winter. Effective removal of the EOCs by a two-stage disc tube reverse osmosis (DTRO) system led to a significant reduction in their concentration levels (< LOQ ~ 49 ng/L) in treated leachates. Eight EOCs (< LOQ ~ 62.7 ng/L) were detected in the groundwater adjacent to the landfill and had a similar composition pattern to raw leachates. The contamination levels of the target EOCs in groundwater decreased with the distance of sampling sites from the landfill. In soil samples, the occurrence of target EOCs was not consistent with raw or treated landfill leachates. Spatially, no apparent difference in the EOC concentrations was observed in the soil nearby the landfill. Crop plants sorbed the EOCs contained in soil (< LOQ ~ 30.4 ng/L), but they were not able to bioconcentrate the contaminants in either roots or edible parts. Risk assessment suggested that the individual EOC likely posed medium to high risks to aquatic organisms in groundwater while negligible impacts to human health through consumption of vegetables. To the best of our knowledge, this is the first report on the contribution of landfill leachates to EOC contamination in both aquatic and soil environments in East China. Our findings emphasized the importance of investigating EOCs in landfill leachates and accumulative environmental risks of EOCs in the neighboring environment of landfills in China.

Decomposition of naproxen by plasma in liquid process with TiO2 photocatslysts and hydrogen peroxide

Naproxen (NPX), one of the representative non-steroidal anti-inflammatory drug (NSAID) ingredients, was decomposed by plasma in liquid process (PiLP). Strongly oxidized species generated in the plasma field of the PiLP, such as OH radicals, were confirmed by optical emission spectroscopy Increasing the operation parameters (pulse width, frequency and applied voltage) of the power supply promoted plasma field generation and OH radical generation, and affected the NPX decomposition rate. Although the NPX decomposition reaction rate was improved by up to 18-30% by adding TiO₂ photocatalyst powder and H₂O₂ to PiLP, but the optimal addition amount should be determined considering the plasma generation and scavenger effects. A decomposition pathway was proposed, in which NPX was mineralized into CO₂ and H₂O through five intermediates mainly by decarboxylation, demethylation, hydroxylation, and dehydration reactions via hydroxyl radicals.

Prevalence and hazardous impact of pharmaceutical and personal care products and antibiotics in environment: A review on emerging contaminants

Antibiotic resistance is a global health emergency linked to unrestrained use of pharmaceutical and personal care products (PPCPs) as prophylactic agent and therapeutic purposes across various industries. Occurrence of pharmaceuticals are identified in ground water, surface water, soils, and wastewater treatment plants (WWTPs) in ng/L to μg/L concentration range. The prevalence of organic compounds including antimicrobial agents, hormones, antibiotics, preservatives, disinfectants, synthetic musks etc. in environment have posed serious health concerns. The aim of this review is to elucidate the major sources accountable for emergence of antibiotic resistance. For this purpose, variety of introductory sources and fate of PPCPs in aquatic environment including human and veterinary wastes, aquaculture and agriculture related wastes, and other anthropogenic activities have been discussed. Furthermore, genetic and enzymatic factors responsible for transfer and appearance of antibiotic resistance genes are presented. Ecotoxicity of PPCPs has been studied in environment in order to present risk imposed to human and ecological health. As per published literature reports, the removal of antibiotics and related traces being difficult, couples the possibility of emergence of antibiotic resistance and hence sustainability in global water resources. Therefore, research on environmental behavior and control strategies should be conducted along with assessing their chronic toxicity to identify potential human and ecological risks.

Oxidation of diclofenac by birnessite: Identification of products and proposed transformation pathway

Diclofenac (DCF), a widely used non-steroidal anti-inflammatory, reacted readily with birnessite under mild conditions, and the pseudo first order kinetic constants achieved 8.84 × 10^-2 hr^-1. Five products of DCF including an iminoquinone product (2,5-iminoquinone-diclofenac) and four dimer products were observed and identified by tandem mass spectrometry during the reaction. Meanwhile, 2,5-iminoquinone-diclofenac was identified to be the major product, accounting for 83.09% of the transformed DCF. According to the results of spectroscopic Mn(III) trapping experiments and X-ray Photoelectron Spectroscopy, Mn(IV) contained in birnessite solid was consumed and mainly converted into Mn(III) during reaction process, which proved that the removal of DCF by birnessite was through oxidation. Based on the identified products of DCF and the changes of Mn valence state in birnessite solid, a tentative transformation pathway of DCF was proposed.

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.

Trace organic contaminants in field-scale cultivated alfalfa, soil, and pore water after 10 years of irrigation with reclaimed wastewater

Several studies have assessed the presence of trace organic contaminants (TrOCs) in reclaimed wastewater and their uptake into crops but there are limited data from field-scale studies. In this research, we studied the fate of 12 TrOCs in wastewater samples, 11 in plants and in soil pore water, and 10 in soil at an agricultural research farm, which was irrigated with reclaimed wastewater for more than 10 years. First, we examined the presence of the compounds in the primary, secondary, and treated effluent of a regional water reclamation facility which provides the irrigation water. The agricultural field produced alfalfa, and we measured the contaminants in the alfalfa, soil, and pore water. Reclaimed wastewater contained 11 of 12 TrOCs, with concentrations ranging from 26 ± 9 ng/L (DEET) to 1539 ± 1899 ng/L (trimethoprim). Atrazine was not detected. Pore water collected during non-irrigating periods contained all analyzed TrOCs, from 3 ± 0.1 ng/L (diphenhydramine) to 343 ± 360 ng/L (primidone). TrOCs measured in pore water samples indicated that they may leach to shallow groundwater even when fields are not being irrigated. Soils from 0 to 60 cm contained nine TrOCs from below the reporting limit (fluoxetine) to 329 ng/g (carbamazepine). Atrazine was not detected. TrOC concentrations decreased with increasing soil depth, except carbamazepine, which was more recalcitrant. Nine TrOCs were present in the shoots and leaves of alfalfa grown in the reclaimed wastewater irrigated plots, at concentrations ranging from <1 ng/g (diphenhydramine and fluoxetine) to 49 ng/g dry weight (carbamazepine). Atrazine and caffeine were not detected. We estimated that a maximum of 14% of DEET from the reclaimed wastewater was accumulated in alfalfa. Overall, despite some accumulation of TrOCs in the soil, alfalfa uptake was limited, which results in low exposure to foraging animals.

Emerging pollutants (EPs) in Latin América: A critical review of under-studied EPs, case of study -Nonylphenol

Emerging contaminants (EPs) represent a significant risk to human, ecological and environmental health. Although progress has been made in establishing monitoring in environmental matrices, health effects, legislation and control, there are still problems associated with regional bias and the types of EPs commonly assessed, which may underestimate the risk to health. In Latin America there are limited reports on environmental monitoring of EPs and it is generally focused on wastewater. This review identifies the current research deficiencies for emerging contaminants in the Latin American region, and we address the case of nonylphenol as an under-studied EP in the region. Nonylphenol is a degradation product of nonylphenol ethoxylate, which is a surfactant widely used in the manufacture of detergents in Latin America, environmental concentrations have been reported, predominantly in water, and the possible effects on species in this region have been also described. The importance of the review of this compound in the region lies in the fact that the Rotterdam Convention has catalogued nonylphenol as a severely restricted compound, so it is necessary to establish measures for its restriction and change to a sustainable technology. Finally, the example of NP presented in this review highlights the lack of regulation in Latin America regarding to EPs, resulting in the contamination of wastewater, effluents, rivers and drinking water. It is imperative to determine the potential effects, occurrence and concentration levels to improve the regulation of these pollutants in a timely manner.

Uptake of atenolol, carbamazepine and triclosan by crops irrigated with reclaimed water in a Mediterranean scenario

Water scarcity is a natural condition in the Mediterranean rim countries. In this region, reuse of reclaimed water (RW) from wastewater treatment plants (WWTPs) is becoming a potential source for highly water-demanding activities such as agriculture. However, the removal capacity of contaminants in regular WWTPs has been found to be limited. Considering a Mediterranean scenario, this research investigated the plant uptake and translocation of three representative pharmaceuticals and personal care products (PPCPs) typically present in RW samples from a WWTP located in an urban area in Spain, and assessed the potential risk to humans from plant consumption. The RW samples were collected and analyzed for three representative PPCPs (atenolol -ATN-, carbamazepine -CBZ- and triclosan -TCS-). The target contaminants were also spiked at two levels in the RW samples to consider two worst-case scenarios. Three plant models (lettuce, maize and radish) were grown outdoors and irrigated with four treatments: tap water; RW samples, and the two spiked RW samples. Generally speaking, results revealed an efficient root uptake for the three PPCPs regardless of plant species and fortification level, and suggested an interaction effect of treatment and plant organ. Different bioaccumulation and translocation potentials of the three PPCPs were seen into the aerial organs of the plants. Overall, these observations support the idea that factors including the physico-chemical properties of the PPCPs and physiological plant variables, could be responsible for the differential accumulation and translocation potentials observed. These variables could be critical for crops irrigated with RW in regions with extended dry seasons, high solar incidence and low annual rainfall such as those in the Mediterranean rim where plants are subjected to high transpiration rates. However, the results obtained from this experimental approach suggested a negligible risk to humans from consumption of edible plants irrigated with RW samples with presence of PPCPs, despite the fact that the three representative PPCPs under study accumulated efficiently in the plants.

Risk assessment of contaminants of emerging concern in the context of wastewater reuse for irrigation: An integrated modelling approach

Direct reuse of reclaimed wastewater (RWW) in agriculture has recently received increasing attention as a possible solution to water scarcity. The presence of contaminants of emerging concern (CECs) in RWW can be critical, as these chemicals can be uptaken in irrigated crops and eventually ingested during food consumption. In the present study, an integrated model was developed to predict the fate of CECs in water reuse systems where RWW is used for edible crops irrigation. The model was applied to a case study where RWW (originating from a municipal wastewater treatment plant) is discharged into a water channel, with subsequent irrigation of silage maize, rice, wheat and ryegrass. Environmental and human health risks were assessed for 13 CECs, selected based on their chemical and hazard characteristics. Predicted CEC concentrations in the channel showed good agreement with available measurements, indicating potential ecotoxicity of some CECs (estrogens and biocides) due to their limited attenuation. Plant uptake predictions were in good agreement with existing literature data, indicating higher uptake in leaves and roots than fruits. Notably, high uncertainties were shown for weakly acidic CECs, possibly due to degradation in soil and pH variations inside plants. The human health risk due to the ingestion of wheat and rice was assessed using the threshold of toxicological concern and the hazard quotient. Both approaches predicted negligible risk for most CECs, while sulfamethoxazole and 17α-ethinylestradiol exhibited the highest risk for consumers. Alternative scenarios were evaluated to identify possible risk minimization strategies (e.g., adoption of a more efficient irrigation system).

Solvothermal synthesis and characterization of novel [Ni(ii)(Tpy)(Pydc)]·2H2O metal–organic framework as an adsorbent for the uptake of caffeine drug from aqueous solution

[Ni(ii)(Tpy)(Pydc)]·2H₂O metal–organic framework is capable of adsorbing 98.4 mg g⁻¹ of caffeine at 30 °C, pH 4 for 1 hour.

Degradation kinetics and mechanism of diclofenac by UV/peracetic acid

In this work, the degradation kinetics and mechanism of diclofenac (DCF) by UV/peracetic acid (PAA) was investigated.

Prioritizing environmental risks of pharmaceuticals and personal care products in reclaimed water on urban green space in Beijing

Pharmaceuticals and personal care products (PPCPs) in reclaimed water can enter into soil, groundwater, and air during the irrigation of urban green spaces, leading to potential risks due to their negative effects of feminization, on root elongation, and as carcinogens. In this study, a validated HYDRUS-1D model by field experiments and an exposure model were used to simulate the distributions of 67 PPCPs detected in the effluent from municipal wastewater treatment plants of Beijing under two scenarios (1, uniform irrigation concentrations; 2, detected irrigation concentrations) in soil, groundwater, and air. To determine the priority ranks of the 67 PPCPs, the effect values of the PPCPs in soil, groundwater, and air were calculated on the basis of distributions and toxicity data, and then weighted and scored. Under scenario 1, roxithromycin, medroxyprogesterone acetate, and megestrol acetate, characterized by high adsorption and low volatilization and degradation, had the highest accumulations in soil, and ofloxacin, characterized by the lowest degradation and adsorption, had the highest leaching to groundwater. The highest volatilization was observed for galaxolide abbalide, tonalid, and dioctyl phthalate. Under scenario 2, based on their overall scores and priority ranks, the 67 PPCPs were divided into three groups: I, high priority; II, moderate priority; III, low priority. Of the 67 PPCPs, 17 were classified in group I, with the highest priority rankings for ofloxacin, 17α-ethynylestradiol, dibutyl phthalate, dioctyl phthalate, and sulfamethoxazole. In group III (total 33 PPCPs), 28 of the PPCPs were not of urgent concern under reclaimed water irrigation in Beijing.

The hitchhiker's guide to core samples: Key issues and lessons learned

Core samples may be used as valuable geochronometers for storing historical pollution footprints of organic pollutants. A number of studies have used core samples to evaluate temporal depositions, loading inventories, and effectiveness of environmental mitigation measures. However, in order to get a reliable estimation, certain prerequisites must be satisfied to rule out various confounding factors such as biomixing and melting. This review aims to understand when core samples can or cannot be used as natural archives for organic pollutants. First, we systematically review existing studies of organic pollutants in soil, sediment and ice cores and possible factors that may influence post-depositional fate of chemicals. Then, building on field evidence, model simulation and laboratory leaching tests findings, we discuss issues of post-depositional downward movement in detail. To assist future core sample studies, we summarize lessons learned on study design in the context of sampling design, data analysis, and data reporting. In particular, the combination of a careful study design and appropriate numerical model(s) will help to elevate core samples as a more reliable tool for retrospective understanding of chemical pollution. This review is an initial step toward a better and more accurate use of core samples, and further interdisciplinary cooperation is needed to develop standardized protocols, guidelines and tools.

Realistic low-doses of two emerging contaminants change size distribution of an annual flowering plant population

HHCB [1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran] and 4-tert-octylphenol [4-(1,1,3,3-tetramethylbutyl)phenol] are widely used emerging contaminants that have the potential to cause adverse effects in the environment. The purpose of this study was to observe if and how environmentally realistic concentrations of these contaminants alter growth in plant populations. It was hypothesized that within an exposed Gypsophila elegans Bieb (annual baby's breath) population especially fast-growing seedlings are impaired even when the population mean is unaffected, and small doses can cause hormesis and, thus, an increase in shoot or root length. In a dose-response experiment, an experimental population of G. elegans was established (total 15.600 seeds, 50 seeds per replicate, 24 replicates per concentration, 5.2 seedlings/cm²) and exposed to 12 doses of HHCB or 4-tert-octylphenol. After five days, shoot and root length values were measured and population averages, as well as slow- and fast-growing subpopulations, were compared with unexposed controls. Growth responses were predominantly monophasic. HHCB seemed to selectively inhibit both root and shoot elongation among slow- and fast-growing individuals, while 4-tert-octylphenol selectively inhibited both root and shoot elongation of mainly fast-growing seedlings. The ED₅₀ values (dose causing 50% inhibition) revealed that the slow-growing seedlings were more sensitive and fast-growing seedlings less sensitive than the average of all individuals. Although there was toxicant specific variation between the effects, selective toxicity was consistently found among both slow- and fast-growing plants starting already at concentrations of 0.0067 µM, that are usually considered to be harmless. This study indicates that these contaminants can change size distribution of a plant population at low concentrations in the nM/µM range.

Aerobic and Anaerobic Biological Degradation of Pharmaceutically Active Compounds in Rice Paddy Soils

One of the concerns against the use of sewage sludge for agricultural purposes is emerging contaminants contained in sewage sludge. Most of the studies on biological degradation of pharmaceutically active compounds in agricultural land were carried out with water-unsaturated soils under relatively aerobic conditions. In this study, the degradation of pharmaceuticals mainly including non-steroidal anti-inflammatory drugs (NSAIDs) was investigated in Asian rice paddy soils that are flooded in anaerobic condition. The experimental results showed that the concentrations of the target pharmaceuticals excluding the exception of naproxen were poorly decreased in anaerobic condition. On the other hand, the microbial communities of the soils contained the aerobic degraders of clofibric acid and diclofenac, which are generally persistent in biological wastewater treatment. The higher degradation rates in aerobic condition suggest the possibility of enhanced degradation of pharmaceuticals by supplying oxygen with plowing anaerobic rice fields or with drying the field in off-season for farming.

Stereoselective effects of ibuprofen in adult zebrafish (Danio rerio) using UPLC-TOF/MS-based metabolomics

Ibuprofen (IBU), as a commonly used non-steroidal anti-inflammatory drug (NSAID) and pharmaceutical and personal care product (PPCP), is frequently prescribed by doctors to relieve pain. It is widely released into environmental water and soil in the form of chiral enantiomers by the urination and defecation of humans or animals and by sewage discharge from wastewater treatment plants. This study focused on the alteration of metabolism in the adult zebrafish (Danio rerio) brain after exposure to R-(-)-/S-(+)-/rac-IBU at 5 μg L^-1 for 28 days. A total of 45 potential biomarkers and related pathways, including amino acids and their derivatives, purine and its derivatives, nucleotides and other metabolites, were observed with untargeted metabolomics. To validate the metabolic disorders induced by IBU, 22 amino acids and 3 antioxidant enzymes were selected to be quantitated and determined using targeted metabolomics and enzyme assay. Stereoselective changes were observed in the 45 identified biomarkers from the untargeted metabolomics analysis. The 22 amino acids quantitated in targeted metabolomics and 3 antioxidant enzymes determined in enzyme assay also showed stereoselective changes after R-(-)-/S-(+)-/rac-IBU exposure. Results showed that even at a low concentration of R-(-)-/S-(+)-/rac-IBU, disorders in metabolism and antioxidant defense systems were still induced with stereoselectivity. Our study may enable a better understanding of the risks of chiral PPCPs in aquatic organisms in the environment.

Phytotoxic activity of diclofenac: Evaluation using a model green alga Chlamydomonas reinhardtii with atrazine as a reference substance

Human activities have caused increasing inputs of pharmaceuticals to the environment and diclofenac (DF) is one of the most commonly detected in freshwater systems. The aim of this study was to determine the impact of DF on a freshwater green alga as a non-target organism. For DF toxicity evaluation, its effects on a model organism Chlamydomonas reinhardtii were compared with effects caused by the herbicide atrazine (AT). EC₅₀ values were about 135 mg/L for DF and 78 mg/L for AT, respectively. Both toxicants enhanced H₂O₂ production by the cells (144% and 178% of control for AT and DF, respectively) and stimulated catalase activity (≈200% of control). Activity of ascorbate peroxidase was elevated in AT-cells but not in DF-treated cells. DF did not influence dark respiration of the cells, whereas AT inhibited this process by about 50% compared to the control. Both toxicants caused photosynthesis inhibition. Analysis of parameters of chlorophyll a fluorescence in vivo showed diminishment of a performance index (PI) in both DF- and AT-treated cells (≈50% of control), but the reasons for the changes detected were different. AT diminished the efficiency of electron transport between PS II and PS I without significant inhibition of PS II or PS I reaction centers (RCs). In contrast to AT, DF seemed to influence directly PS II RCs. The fraction of active PS II RCs was lowered in DF-treated cells, but energy flux per active RC increased. Our study indicates that DF phytotoxicity results mainly from photosynthesis inhibition due to "silencing" of a fraction of PS II RCs.

Impacts of irrigation water sources and geochemical conditions on vertical distribution of pharmaceutical and personal care products (PPCPs) in the vadose zone soils

Groundwater pollution by emerging contaminants, such as pharmaceutical and personal care products (PPCPs), has caused increasing concerns around the world. The vadose zone is an active zone where lithosphere, hydrosphere and biosphere interact. It is an important medium for PPCPs removal and entry into groundwater from irrigation using wastewater or polluted surface water. In the present study, the occurrence and distribution of eleven PPCPs in areas with a vadose zone (up to 16 m) was investigated from wastewater irrigated farmland, groundwater irrigated farmland and a seasonal river course in Beijing (China). Nine out of eleven PPCPs were detectable, and carbamazepine and caffeine had the highest detection frequencies, above 50%. The PPCPs were detectable deep in 16 m below ground level (bgl), and their concentrations ranged from <LOD (limit of detection) to 12.5 μg/kg. Compared to the vadose zone soils irrigated with groundwater, wastewater-irrigated vadose zone soils had significantly higher PPCPs detection frequencies and contamination levels, suggesting the important roles of irrigation water sources on PPCPs accumulation and transport in the vadose zone. Additionally, PPCPs vertical distribution presented a bell-shape pattern in the vadose zone soils with wastewater irrigation, peaking at 3-6 m bgl. Redundancy analysis (RDA) indicated a significant correlation between PPCPs concentrations in the vadose zone soils and geochemical variables, including available potassium and silt content. This study provides important evidence on the influential factors of PPCPs accumulation and migration in the vadose zone soils resulted from wastewater irrigation. The incomplete removal of PPCPs poses certain risks in subsurface environment, potentially challenging groundwater quality and drinking water safety.

Effects of 18 pharmaceuticals on the physiological diversity of edaphic microorganisms

Pharmaceutical residues can enter the terrestrial environment through the application of recycled water and contaminated biosolids to agricultural soils, were edaphic microfauna can would be threatened. This study thus assessed the effect of 18 widely consumed pharmaceuticals, belonging to four groups: antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), blood lipid-lowering agents (BLLA) and β-blockers, on the physiology of soil microbial communities from a ecological crop field. Biolog EcoPlates, containing 31 of the most common carbon sources found in forest and crop soils, were used to calculate both the averaged well colour development (AWCD), as an indicator of the entire capacity of degrading carbon sources, and the diversity of carbon source utilization, as an indicator of the physiological diversity. The results show that pharmaceuticals impact microbial communities by changing the ability of microbes to metabolize different carbon sources, thus affecting the metabolic diversity of the soil community. The toxicity of the pharmaceuticals was inversely related to the log K_ow; indeed, NSAIDs were the least toxic and antibiotics were the most toxic, while BLLA and β-blockers presented intermediate toxicity. The antibiotic sulfamethoxazole imposed the greatest impact on microbial communities at concentrations from 100 mg/L, followed by the other two antibiotics (trimethoprim and tetracycline) and the β-blocker nadolol. Other chemical parameters (i.e. melting point, molecular weight, pK_a or solubility) had little influence on toxicity. Microbial communities exposed to pharmaceuticals having similar physicochemical characteristics presented similar physiological diversity patterns of carbon substrate utilization. These results suggest that the repeated amendment of agricultural soils with biosolids or sludges containing pharmaceutical residuals may result in soil concentrations of concern regarding key ecological functions (i.e. the carbon cycle).

Fate of pharmaceuticals in soil after application of STPs products: Influence of physicochemical properties and modelling approach

Depurated effluents can be employed as reclaimed water for irrigation in regions with low precipitations, while nutrients-rich biosolids are usually applied as fertilizer for agricultural purposes. However, both practices may result in the accumulation of micropollutants in the soil compartment, the contamination of groundwater, and/or their biotransfer to different living organisms until they finally may reach human receptors. The fate and transport of seven pharmaceutical and personal care products (PPCPs) with different physicochemical properties was analysed for these scenarios employing two different models: the buckets model and the HYDRUS-1D software package. The results indicated that these compounds have a low potential to contaminate groundwater in the type of soil under study (silty loam), although triclosan tended to accumulate in the top layers of the soil. Similar conclusions were reached through both models, although they predicted different solute plant uptake and accumulation patterns of the evaluated compounds. Therefore, the buckets model can be considered as an adequate option to perform a screening level assessment of these compounds. However, HYDRUS-1D could provide more information on the fate of pharmaceuticals in soil, thus contributing to reduce the uncertainty already associated to PPCPs. Additionally, the significant difference of the Hazard Index (HI) obtained from a human health risk assessment performed using the estimated soil concentrations from both models also contributed to recommend the use of a model that considers all the relevant mechanisms of mass transfer to reduce overestimation of risk.

Estrogenic compounds in Tunisian urban sewage treatment plant: occurrence, removal and ecotoxicological impact of sewage discharge and sludge disposal

The occurrence, fate and ecotoxicological assessment of selected estrogenic compounds were investigated at Tunisian urban sewage treatment plant. The influents, effluents, as well as primary, secondary and dehydrated sludge, were sampled and analyzed for the target estrogens to evaluate their fate. All target compounds were detected in both sewage and sludge with mean concentrations from 0.062 to 0.993 μg L^-1 and from 11.8 to 792.9 μg kg^-1dry weight, respectively. A wide range of removal efficiencies during the treatment processes were observed, from 6.3 % for estrone to 76.8 % for estriol. Ecotoxicological risk assessment revealed that the highest ecotoxicological risk in sewage effluent and dehydrated sludge was due to 17β-estradiol with a risk quotient (RQ) of 4.6 and 181.9, respectively, and 17α-ethinylestradiol with RQ of 9.8 and 14.85, respectively. Ecotoxicological risk after sewage discharge and sludge disposal was limited to the presence of 17β-estradiol in dehydrated-sludge amended soil with RQ of 1.38. Further control of estrogenic hormones in sewage effluent and sludge is essential before their discharge and application in order to prevent their introduction into the natural environment.

Effect of soil properties, heavy metals and emerging contaminants in the soil nematodes diversity

Among soil organisms, nematodes are seen as the most promising candidates for bioindications of soil health. We hypothesized that the soil nematode community structure would differ in three land use areas (agricultural, forest and industrial soils), be modulated by soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.), and strongly affected by high levels of heavy metals (Cd, Pb, Zn, Cr, Ni, Cu, and Hg) and emerging contaminants (pharmaceuticals and personal care products, PPCPs). Although these pollutants did not significantly affect the total number of free-living nematodes, diversity and structure community indices vastly altered. Our data showed that whereas nematodes with r-strategy were tolerant, genera with k-strategy were negatively affected by the selected pollutants. These effects diminished in soils with high levels of heavy metals given their adaptation to the historical pollution in this area, but not to emerging pollutants like PPCPs.

Sorption of diclofenac and naproxen onto MWCNT in model wastewater treated by H2O2 and/or UV

The application of oxidation processes such as UV and/or H2O2 will change the physicochemical properties of carbon nanotubes (CNT). It may affect the sorption affinity of CNT to different contaminants and then affect their fate in the environment. In the present study the adsorption of two very common used pharmaceuticals (diclofenac and naproxen) onto CNT treated by UV, H2O2 or UV/H2O2 was investigated. Four different adsorption models (Freundlich, Langmuir, Temkin, Dubinin-Radushkevich) were tested. The best fitting of experimental data was observed for Freundlich or Langmuir model. The significant relationships between Q calculated from Langmuir model with O% and dispersity were observed. Kinetics of diclofenac and naproxen followed mainly pseudo-second order indicating for chemisorption limiting step of adsorption. The data showed that the mechanism of sorption was physical or chemical depending on the type of CNT modification.

Risk assessment of persistent pharmaceuticals in biosolids: Dealing with uncertainty

A screening-level risk assessment of biosolids-borne PPCPs in agricultural scenarios was developed in this work. While several of these compounds are efficiently removed in sewage treatment plants (STPs), others are recalcitrant to degradation and can be found in sludge at significant levels. As the rate of biosolids reuse for fertilising and/or amendment purposes is increasing, it is necessary to evaluate the fate in soil and possible biotransfer of this type of pollutants in the long-term. The study includes six compounds that were selected considering data availability, presence in sludge and persistence. Due to the scarce data still present in literature, a probabilistic assessment to address uncertainty was developed. A 95th percentile of the hazard index (HI) exceeding 1 was obtained, with main contributions of triclosan and carbamazepine. Although these estimates were obtained under a worst-case approach, and that they can vary depending on scenario characteristics, they change the least-concern classification associated to the presence of PPCPs in biosolids. A sensitivity analysis indicates the high influence of application rate and sludge concentration level on the results. Thus, the importance of developing new strategies of removal in advanced STPs and the establishment of a specific biosolids reuse regulation including this type of compounds acquires an added significance.

Spatial distribution and migration of nonylphenol in groundwater following long-term wastewater irrigation

Seen as a solution to water shortages, wastewater reuse for crop irrigation does however poses a risk owing to the potential release of organic contaminants into soil and water. The frequency of detection (FOD), concentration, and migration of nonylphenol (NP) isomers in reclaimed water (FODRW), surface water (FODSW), and groundwater (FODGW) were investigated in a long-term wastewater irrigation area in Beijing. The FODRW, FODSW and FODGW of any or all of 12 NP isomers were 66.7% to 100%, 76.9% to 100% and 13.3% to 60%, respectively. The mean (±standard deviation) NP concentrations of the reclaimed water, surface water, and groundwater (NPRW, NPSW, NPGW, repectively) were 469.4±73.4 ng L(-1), 694.6±248.7 ng(-1) and 244.4±230.8 ng(-1), respectively. The existence of external pollution sources during water transmission and distribution resulted in NPSW exceeding NPRW. NP distribution in groundwater was related to the duration and quantity of wastewater irrigation, the sources of aquifer recharge, and was seen to decrease with increasing aquifer depth. Higher riverside infiltration rate nearby leads to higher FODGW values. The migration rate of NP isomers was classified as high, moderate or low.

Bisphenol A, nonylphenols, benzophenones, and benzotriazoles in soils, groundwater, surface water, sediments, and food: a review

Contaminants of emerging concern (CECs) are not commonly monitored in the environment, but they can enter the environment from a variety of sources. The most worrying consequence of their wide use and environmental diffusion is the increase in the possible exposure pathways for humans. Moreover, knowledge of their behavior in the environment, toxicity, and biological effects is limited or not available for most CECs. The aim of this work is to edit the state of the art on few selected CECs having the potential to enter the soil and aquatic systems and cause adverse effects in humans, wildlife, and the environment: bisphenol A (BPA), nonylphenol (NP), benzophenones (BPs), and benzotriazole (BT). Some reviews are already available on BPA and NP, reporting about their behavior in surface water and sediments, but scarce and scattered information is available about their presence in soil and groundwater. Only a few studies are available about BPs and BT in the environment, in particular in soil and groundwater. This work summarizes the information available in the literature about the incidence and behavior of these compounds in the different environmental matrices and food. In particular, the review focuses on the physical-chemical properties, the environmental fate, the major degradation byproducts, and the environmental evidence of the selected CECs.

Photocatalytic treatment of pharmaceutical wastewater using new multiwall-carbon nanotubes/TiO2/SiO2 nanocomposites

For the photocatalytic removal of bisphenol A (BPA) and carbamazepine (CBZ) from water solution a new multiwall-carbon nanotubes and TiO2/SiO2 nanocomposites (MWCNT-TiO2-SiO2) were applied. Nanocomposites with the addition of 0.15-17.8 wt% MWCNT show high potential for the removal of both pollutants. The starting concentration of each contaminant was halved during 20 min of UVA irradiation. The decomposition process of CBZ over investigated nanocomposites proceeded differently than it was observed for the classical photocatalyst P25. The kinetics of the removal followed as a pseudo-first order regime with the k1 in range 0.0827-0.1751 min(-1) for BPA and 0.0131-0.0743 min(-1) for CBZ. Toxicity to Vibrio fischeri and Daphnia magna was significantly reduced indicating formation of non-toxic products of photooxidation of tested contaminants.