Accumulation of oxytetracycline and norfloxacin from saline soil by soybeans

Fate of emerging antibiotics in soil-plant systems: A case on fluoroquinolones

Fluoroquinolones (FQs), a class of broad-spectrum antibiotics widely used to treat human and animal diseases globally, have limited adsorption and are often excreted unchanged or as metabolites. These compounds enter the soil environment through feces, urban wastewater, or discharge of biological solids. The fluorine atoms in FQs impart high electronegativity, chemical stability, and resistance to microbial degradation, allowing them to potentially enter food chains. The persistence of FQs in soils raises questions about their impacts on plant growth, an aspect not yet conclusively determined. We reviewed whether, like other organic compounds, FQs are actively absorbed by plants, resulting in bioaccumulation and posing threats to human health. The influx of FQs has led to antibiotic resistance in soil microbes by exerting selective pressure and contributing to multidrug-resistant bacteria. Therefore, the environmental risks of FQs warrant further attention. This work provides a comprehensive review of the fate and behavior of FQs at the plant-environment interface, their migration and transport from the environment into plants, and associated toxicity. Current limitations in research are discussed and prospects for future investigations outlined. Thus, understanding antibiotic behavior in plants and translocation within tissues is not only crucial for ecosystem health (plant health), but also assessing potential human health risks. In addition, it can offer insights into the fate of emerging soil pollutants in plant-soil systems.

Occurrence, Source Apportionment, and Risk Assessment of Antibiotics in Mangrove Sediments from the Lianzhou Bay, China

In recent years, the widespread application of antibiotics has raised global concerns, posing a severe threat to ecological health. In this study, the occurrence, source, and ecological risks of 39 antibiotics belonging to 5 classes in mangrove sediments from Lianzhou Bay, China, were assessed. The total concentrations of the antibiotics (∑39 antibiotics) ranged from 65.45 to 202.24 ng/g dry weight (dw), with an average of 142.73 ± 36.76 ng/g dw. The concentrations of these five classes of antibiotics were as follows: Sulfonamides (SAs) > Tetracyclines (TCs) > Fluoroquinolones (QUs) > Penicillin (PCs) > Macrolides (MLs). The spatial distribution of antibiotics varied as high tidal zone > middle tidal zone > low tidal zone. The total organic carbon (TOC), pH, nitrate (NO3--N), and nitrite (NO2--N) of the sediment significantly influenced the distribution of antibiotics (p < 0.05). A source analysis identified untreated sewage from aquaculture as the primary source of antibiotics in the local mangrove. A risk assessment revealed that ciprofloxacin, norfloxacin, ofloxacin of QUs, and tetracycline of TCs exhibited medium risks to algae in certain sampling sites, while other antibiotics exhibited low or no risks to all organisms. Nevertheless, the total risk of all the detected antibiotics to algae was medium in 95% of the sites. The overall ecological risk level of antibiotics in the middle tidal zone was slightly lower than in the high tidal zone and the lowest in the low tidal zone. In summary, the experimental results provided insights into the fate and transport behaviors of antibiotics in mangrove sediments from Lianzhou Bay.

A novel enrofloxacin-degrading fungus, Humicola sp. KC0924g, isolated from the rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L

A novel enrofloxacin-degrading fungus was isolated from a rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L.. The isolate, designated KC0924g, was identified as a member of the genus Humicola based on morphological characteristics and tandem conserved sequence analysis. The optimal temperature and pH for enrofloxacin degradation by strain KC0924g were 28 °C and 9.0, respectively. Under such condition, 98.2% of enrofloxacin with an initial concentration of 1 mg L-1 was degraded after 72 h of incubation, with nine possible degradation products identified. Four different metabolic pathways were proposed, which were initiated by cleavage of the piperazine moiety, hydroxylation of the aromatic ring, oxidative decarboxylation, or defluorination. In addition to enrofloxacin, strain KC0924g also degraded other fluoroquinolone antibiotics (ciprofloxacin, norfloxacin, and ofloxacin), malachite green (an illegal additive in aquaculture), and leucomalachite green. Pretreatment of cells of strain KC0924g with Cu2+ accelerated ENR degradation. Furthermore, it was speculated that a flavin-dependent monooxygenase was involved in ENR degradation, based on the increased transcriptional levels of these two genes after Cu2+ induction. This work enriches strain resources for enrofloxacin remediation and, more importantly, would facilitate studies on the molecular mechanism of ENR degradation with degradation-related transcriptome available.

Tetracyclines uptake from irrigation water by vegetables: Accumulation and antimicrobial resistance risks

Wastewater irrigation may introduce antibiotic residues in the soil-plant systems. This study aimed to investigate the uptake of tetracyclines by spinach and collard greens and assess associated ecological and human health risks. Synthetic wastewater spiked with 1 ppm and 10 ppm of oxytetracycline, doxycycline, and tetracycline was used to grow vegetables in a greenhouse pot experiment. The uptake and accumulation of the tetracyclines were low and residual concentrations in the soil were negligible. All the tetracyclines were detected at concentrations ranging from 1.68 to 51.41 μg/g (spinach) and 1.94-30.95 μg/g (collard greens). The accumulation rate was in a dose-response scenario with a bioconcentration factor of 6.34 mL/kg (spinach) and 2.64 mL/kg (collard greens). Oxytetracycline had the highest accumulation in leaves, followed by doxycycline and tetracycline, and the residual concentrations followed the same order. The highest residual concentration was in soils receiving 10 ppm oxytetracycline. Residual concentrations in the soil were lower than accumulated levels and exerted negligible ecological risks. Tetracyclines accumulation in spinach significantly differed between the vegetables demonstrating a subspecies difference in uptake and accumulation. Ecological risk quotient (RQ) and human health risk quotient (HQ) were below thresholds that would exert toxicity and resistance selection impacts. Although RQs and HQs are low (<0.1), this study shows that the vegetables accumulate tetracyclines from irrigation water, posing plausible human health risks to allergic individuals. Similarly, the ecological risks cannot be ignored because the synergistic and antagonistic effects of sublethal concentrations can perturb ecosystem processes.

Critical review of phytoremediation for the removal of antibiotics and antibiotic resistance genes in wastewater

Antibiotics in wastewater are a growing environmental concern. Increased prescription and consumption rates have resulted in higher antibiotic wastewater concentration. Conventional wastewater treatment methods are often ineffective at antibiotic removal. Given the environmental risk of antibiotics and associated antibiotic resistant genes (ARGs), finding methods of improving antibiotic removal from wastewater is of great importance. Phytoremediation of antibiotics in wastewater, facilitated through constructed wetlands, has been explored in a growing number of studies. To assess the removal efficiency and treatment mechanisms of plants and microorganisms within constructed wetlands for specific antibiotics of major antibiotic classes, the present review paper considered and evaluated data from the most recent published research on the topics of bench scale hydroponic, lab and pilot scale constructed wetland, and full scale constructed wetland antibiotic remediation. Additionally, microbial and enzymatic antibiotic degradation, antibiotic-ARG correlation, and plant effect on ARGs were considered. It is concluded from the present review that plants readily uptake sulfonamide, macrolide, tetracycline, and fluoroquinolone antibiotics and that constructed wetlands are an effective applied phytoremediation strategy for the removal of antibiotics from wastewater through the mechanisms of microbial biodegradation, root sorption, plant uptake, translocation, and metabolization. More research is needed to better understand the effect of plants on microbial community and ARGs. This paper serves as a synthesis of information that will help guide future research and applied use of constructed wetlands in the field antibiotic phytoremediation and wastewater treatment.

Occurrence, bioaccumulation and ecological risks of antibiotics in the water-plant-sediment systems in different functional areas of the largest shallow lake in North China: Impacts of river input and historical agricultural activities

Antibiotics are widely used and ubiquitous in the environment, which in turn poses potential threat to human health. However, the effects of agricultural activities and river input on the fate and ecological risks of antibiotics in shallow lake are still poorly understood. Surface water, overlying water and pore water, sediments and aquatic plant samples in the historical planting subarea (PA), historical aquaculture subarea (AU), inflow subarea (IW), discharge subarea (DC), and conservation subarea (CK) of Baiyangdian Lake were collected and analyzed. Our results revealed that the total antibiotic concentrations ranged from 85.33 ng/L to 1631.47 ng/L in waters and from 66.90 ng/g to 177.03 ng/g in sediments. Generally, the total antibiotic concentrations introduced by planting activity in surface water, overlying water and sediments were higher and the levels of total antibiotics in pore water were more affected by river input. In addition, three quinolones (QNs) and two tetracyclines (TCs) were dominant antibiotics in almost five subareas. The pseudo-partitioning coefficient k_d(pw) and bioaccumulation factor (BAF) of antibiotics varied according to the effects of river input and historical agricultural activities. The ecological risk (RQ) of antibiotics from agricultural activities was higher than that from river input. The norfloxacin (NOR) in pore water showed high RQ, which contributed to a large proportion (>50 %) of the combined ecological risks (∑RQs) except for surface water. Therefore, NOR should be used as the primary ecological risk control index for antibiotic contamination management in the BYD. ∑RQs showed high risk in water in the five subareas. This study can act as a reference for governments to formulate effective management strategies for protecting the ecological health of lakes.

Fluoroquinolone antibiotics: Occurrence, mode of action, resistance, environmental detection, and remediation - A comprehensive review

Antibiotics play an essential role in the medical healthcare world, but their widespread usage and high prevalence have posed negative environmental consequences. During the past few decades, various antibiotic drugs have been detected in aquatic and terrestrial ecosystems. Among them, the Fluoroquinolones (FQ) group is ubiquitous in the environment and has emerged as a major environmental pollutant. FQs are very significant, broad-spectrum antibiotics used in treating various pathogenic diseases of humans and animals. The most known and used FQs are ciprofloxacin, norfloxacin, ofloxacin, levofloxacin, enrofloxacin, danofloxacin, and moxifloxacin. After human and animal administration, about 70% of these drugs are excreted out in unaltered form into the environment. Besides, wastewater discharge from pharmaceutical industries, hospitals, and agriculture runoff is the major contributor to the accumulation of FQs into the ecosystem. Their long-term presence in the environment creates selection pressure on microorganisms and contributes to the emergence of multi-drug-resistant bacteria. In addition to the resistance, these antibiotics also impose ecotoxicological effects on various animals and plant species. The presence of the fluorine atom in Fluoroquinolones makes them highly electronegative, strong, recalcitrant, and less compatible with microbial degradation. Many biological and chemical processes have been invented and successfully implemented during the past few decades for the elimination of these pollutants from the environment. This review provides a detailed overview of the classification, occurrence, distribution, and ecotoxicological effects of Fluoroquinolones. Their modes of action, resistance mechanism, detection and analysis methods, and remediation strategies have also been discussed in detail.

Fate and ecological risks of antibiotics in water-sediment systems with cultivated and wild Phragmites australis in a typical Chinese shallow lake

River carrying antibiotics from upstream posed serious threats to receiving lake, and plants might had effects on antibiotics. Therefore, samples of waters, sediments and tissues of cultivated and wild Phragmites australis were collected to analyse antibiotics fate and ecological risks (RQs) in Zaozhadian Lake. Our results revealed that the total antibiotics showed an increasing tendency in surface/pore water and P. australis tissues and a decreasing tendency in overlying water and sediments from the lake entrance to the centre. The bioaccumulation factors (BAFs) of two sulfonamides (SAs) and three quinolones (QNs) increased in sediments and decreased in those of erythromycin in pore water from Site 1 to Site 11. Three QNs and two tetracyclines (TCs) were dominant antibiotics in pore water/sediment and surface/overlying water respectively. Higher levels of two SAs in surface/pore water and two macrolides (MAs) in overlying/pore water and sediments were observed in the wild P. australis region, while higher values of two TCs in overlying/pore water and three QNs in sediment were observed in the cultivated P. australis region. Higher BAFs of SAs and QNs in sediments were observed in the cultivated and wild P. australis region respectively. The RQs of oxytetracycline and two MAs posed moderate risks in surface/overlying water from more than 50% of sampling sites. Norfloxacin exhibited moderate RQ and low ∑RQ levels in sediments, and showed high risk in pore water. Our findings imply that much more attention should be given to the antibiotics from river inputs and management normatives to control antibiotic pollution.

Synthetic organic antibiotics residues as emerging contaminants waste-to-resources processing for a circular economy in China: Challenges and perspective

Synthetic antibiotics have been known for years to combat bacterial antibiotics. But their overuse and resistance have become a concern recently. The antibiotics reach the environment, including soil from the manufacturing process and undigested excretion by cattle and humans. It leads to overburden and contamination of the environment. These organic antibiotics remain in the environment for a very long period. During this period, antibiotics come in contact with various flora and fauna. The ill manufacturing practices and inadequate wastewater treatment cause a severe problem to the water bodies. After pretreatment from pharmaceutical industries, the effluents are released to the water bodies such as rivers. Even after pretreatment, effluents contain a significant number of antibiotic residues, which affect the living organisms living in the water bodies. Ultimately, river contaminated water reaches the ocean, spreading the contamination to a vast environment. This review paper discusses the impact of synthetic organic contamination on the environment and its hazardous effect on health. In addition, it analyzes and suggests the biotechnological strategies to tackle organic antibiotic residue proliferation. Moreover, the degradation of organic antibiotic residues by biocatalyst and biochar is analyzed. The circular economy approach for waste-to-resource technology for organic antibiotic residue in China is analyzed for a sustainable solution. Overall, the significant challenges related to synthetic antibiotic residues and future aspects are analyzed in this review paper.

Antibiotic tolerance and degradation capacity of the organic pollutant-degrading bacterium Rhodococcus biphenylivorans TG9T

Antibiotics are ubiquitous in soil due to natural ecological competition, as well as emerging contaminants due to anthropogenic inputs. Under environmental factors like antibiotic stress, some bacteria, including those that degrade environmental pollutants, can enter a dormant state as a survival strategy, thereby limiting their metabolic activity and function. Dormancy has a critical influence on the degradative activity of bacteria, dramatically decreasing the rate at which they transform organic pollutants. To better understand this phenomenon in environmental pollutant-degrading bacteria, we investigated dormancy transitions induced with norfloxacin in Rhodococcus biphenylivorans TG9^T using next-generation proteomics, proteogenomics, and additional experiments. Our results suggest that exposure to norfloxacin inhibited DNA replication, which led to damage to the cell. Dormant cells then likely triggered DNA repair, particularly homologous recombination, for continued survival. The results also indicated that substrate transport (ATP-binding cassette transporter), ATP production, and the tricarboxylic acid (TCA) cycle were repressed during dormancy, and degradation of organic pollutants was down-regulated. Given the widespread phenomenon of dormancy among bacteria involved in pollutant removal systems, this study improves our understanding of possible implications of antibiotic survival strategies on biotransformation of mixtures containing antibiotics as well as other organics.

Phytotoxicity and Accumulation of Antibiotics in Water Lettuce (Pistia stratiotes) and Parrot Feather (Myriophyllum aquaticum) Plants under Hydroponic Culture Conditions

The aim of this research was to investigate the accumulation of antibiotics in two kinds of plants. The hydroponic culture solution included a mixture of antibiotics, including three commonly used antibiotics in South Korea: norfloxacin (NOR), sulfamethazine (SMZ), and tetracyclines (TC). None of these antibiotics were detected in the shoots of water lettuce plants, only in the roots. However, in parrot feather plants, antibiotics were detected in both the shoots and the roots, with higher amounts detected in the shoots than in the roots. SMZ and TC were most likely to be detected in the roots and shoots of water lettuce and parrot feather plants, and about one-third of the NOR administered was later detected in the plants. The BCF (bioconcentration factor) of antibiotics ranged from 0.24 to 0.78, while that of NOR was much lower, ranging from 0.24 to 0.38. The SMZ (0.59–0.64) and TET (0.72–0.78) exhibited higher uptake accumulation in the water lettuce tissues compared with the parrot feather plants.

Effect of iron plaque on antibiotic uptake and metabolism in water spinach (Ipomoea aquatic Forsk.) grown in hydroponic culture

Ferrous ion was added to the culture solution, followed by the introduction of tetracyclines (TCs), to explore the effect of iron plaque (IP) on the uptake and translocation of TCs by water spinach (Ipomoea aquatic Forsk.). The adsorption amount of TCs on the root surface positively correlated with the amount of IP, except for doxycycline and minocycline. The bioconcentration factor of TCs in roots increased and fitted well with the amount of IP. The concentration of TCs in acrial tissues was three to four orders of magnitude lower than that in roots, and the translocation factor of TCs also fitted well with the amount of IP in a negative linear relationship. Furthermore, IP significantly influenced the metabolism of TCs in water spinach. The accumulation of TC metabolites increased with the increment of IP in roots rather than in acrial tissues, which showed the significance of IP in the metabolism and accumulation of TCs in aquatic plants. Therefore, the metabolism of TCs should not be ignored if IP is induced on the root surface, and the distribution of metabolites should be taken into consideration for the risk assessment and antibiotic pollution control for aquatic plants.

Spatiotemporal distribution, source apportionment and combined pollution of antibiotics in natural waters adjacent to mariculture areas in the Laizhou Bay, Bohai Sea

The spatiotemporal distribution, source apportionment and combined pollution of 14 antibiotics in natural waters adjacent to mariculture farms of Laizhou Bay in the Bohai Sea were studied. The contribution proportion and quantity of each potential pollution source to antibiotics in natural water bodies were quantitatively described. The correlations between heavy metals and antibiotics and their underlying mechanisms in natural and aquaculture water environment were analyzed. Fourteen antibiotics were detected in natural water and sediment in the coastal area of Laizhou Bay. The maximum concentrations of sulfamethazine and trimethoprim in water reached tens or even hundreds of μg/L in winter. Trimethoprim was the main antibiotic in natural water bodies in winter and summer, and enrofloxacin was the principal antibiotic in sediments. Enrofloxacin, ciprofloxacin and oxytetracycline were detected in all underground water samples; thus, control of these antibiotics needs to be made a priority to mitigate groundwater contamination. PCA-MLR revealed that the potential sources of antibiotics in natural waters of Laizhou Bay include the mariculture wastewater (18.3%), the domestic sewage (63.3%) and the livestock wastewater (18.4%). Therefore, the antibiotic burden of Laizhou Bay was principally from the domestic sewage. In natural water, the concentration of Cu was positively correlated with antibiotics, which might be related to the common sources, the competitive adsorption in sediments and the easy complexation characteristic of Cu and antibiotics. Positive correlations among antibiotics and heavy metals were observed in mariculture sediments, while negative relationships were observed in natural sediments.

Irrigation with secondary municipal-treated wastewater: Potential effects, accumulation of typical antibiotics and grain quality responses in rice (Oryza sativa L.)

Using secondary treated wastewater to irrigate paddies presents an exposure pathway for antibiotics to enter the terrestrial food chain. To date, there has been no information on the biochemical reactions and antibiotic uptake in rice plants irrigated with secondary treated wastewater. The present study investigated antibiotic uptake and concentration-response trends in rice tissues and evaluated the effects of typical antibiotics (tetracycline, roxithromycin, ofloxacin, and sulfamethoxazole) on rice growth, grain yield and quality, and rice physiobiochemical characters via irrigation using treated wastewater augmented with varying concentrations (0-500 µg/L) in paddies. The results showed that the antibiotic accumulation in rice plants irrigated with treated wastewater was limited, and the studied antibiotics were not detected in rice grains (edible parts). The ability of rice to withstand certain antibiotics and grow in a healthy manner is attributed to the capacity to maintain reasonably normal photosynthesis activity and to elevate antioxidative defenses. The highest antibiotic concentration (500 µg/L) did not reduce the processing quality of the rice grain, but it enhanced the cooking and eating quality. From the obtained results, it can be concluded that secondary treated wastewater for paddy irrigation is an alternative water resource securing protection from the environment and rice grain quality.

The degradation of oxytetracycline with ferrous oxalate under different light irradiation

Degradation of OTC under different light with Fe²⁺/C2O42- was investigated, and the reaction mechanism was also discussed. Although Fe(II/III)-C2O42- complex could weaken the inhibitory effect of Fe(II/III)-OTC complex on the detection of OTC by HPLC, the acidification could make inhibition become minimal. Response surface methodology was used to optimize the Fe²⁺/C2O42- dosage at low concentrations of Fe²⁺ and H₂C₂O₄. When the OTC concentration was 0.04 mM, the optimal dosage was OTC:Fe²⁺:H₂C₂O₄= 1:1.25:2 to attain a removal rate of 80% after 60 min under simulated solar light, and HO^• for degradation of OTC with Fe²⁺/C2O42+ could be 53%, furthermore, removal rate of OTC just increased 3 percentage points at 60 min when the simulated solar light changed into UV-254 nm, however, OTC could also be degraded for 48.89% removal rate after 3 h illumination of simulated visible light. The influence of Cl^-, CO32-, HCO3-, NO3-, NO2-, or H2PO4- on the degradation of OTC with Fe²⁺/C2O42- under simulated solar light was studied. NO2- could inhibit degradation for NO2- could react with free radicals, but the reason of inhibition of degradation by HCO3-, or CO32- was its influence on pH, whereas Cl^-, NO3- and H2PO4- had no influence on degradation. In addition, when the concentration of CO32- was higher than 4 mM, CO32- could promote the degradation for the direct photolysis of OTC at alkaline (pH > 10). Four products were detected by LC-MS, and the OTC degradation pathway was discussed.

Reclaimed wastewater as a viable water source for agricultural irrigation: A review of food crop growth inhibition and promotion in the context of environmental change

The geographical and temporal distribution of precipitation has and is continuing to change with changing climate. Shifting precipitation will likely require adaptations to irrigation strategies, and because 35% of rainfed and 60% of irrigated agriculture is within 20 km of a wastewater treatment plant, we expect that the use of treated wastewater (e.g., reclaimed wastewater) for irrigation will increase. Treated wastewater contains various organic and inorganic substances that may have beneficial (e.g., nitrate) or deleterious (e.g., salt) effects on plants, which may cause a change in global food productivity should a large change to treated wastewater irrigation occur. We reviewed literature focused on food crop growth inhibition or promotion resulting from exposure to xenobiotics, engineered nanoparticles, nitrogen, and phosphorus, metals, and salts. Xenobiotics and engineered nanoparticles, in nearly all instances, were detrimental to crop growth, but only at concentrations much greater than would be currently expected in treated wastewater. However, future changes in wastewater flow and use of these compounds and particles may result in phytotoxicity, particularly for xenobiotics, as some are present in wastewater at concentrations within approximately an order of magnitude of concentrations which caused growth inhibition. The availability of nutrients present in treated wastewater provided the greatest overall benefit, but may be surpassed by the detrimental impact of salt in scenarios where either high concentrations of salt are directly deleterious to plant development (rare) or in scenarios where soils are poorly managed, resulting in soil salt accumulation.

Evaluation of the fate of nutrients, antibiotics, and antibiotic resistance genes in sludge treatment wetlands

The aim of this research was to analyze the elimination of nutrients, antibiotics as well as antibiotic resistance genes (ARGs) in different sludge treatment wetlands (STWs) with or without reeds and aeration tubes. Five antibiotics, including oxytetracycline, tetracycline, azithromycin, sulfamethoxazole, and sulfadiazine; five ARGs, including two tetracycline ARGs (tetC and tetA), one macrolide ARGs (ermB), and two sulfonamide ARGs (sul1 and sul2); and one integrase gene (intI1) were determined in the surface and bottom layers of three STWs, respectively. The removal efficiencies of antibiotics in the bottom layer were lower than that in the surface layer, while the elimination efficiencies of ARGs showed opposite trend. Strong correlations were observed among the contents of antibiotics as well as related ARGs, and the abundance of ARGs had a strong correlation with intI1. The results demonstrated that the contents of these pollutants decreased during the resting period in all the STWs, while the wetland had reeds and aeration tubes performed the best.

Migration of antibiotic ciprofloxacin during phytoremediation of contaminated water and identification of transformation products

Phytoremediation is an effective and environmentally friendly approach to treat antibiotic contaminated water, however, the mechanisms of migration and transformation of antibiotics in plant tissues are still far from clear. In this study, the floating macrophyte Eichhornia crassipes was exposed to a series of antibiotic ciprofloxacin (CIP) concentrations. The results showed that the CIP was taken up and accumulated in the roots, which were the major accumulative tissue. CIP content increased with lipid content. During cultivation, the root bioconcentration factor (RCF) gradually increased. The average CIP content detected in aerial parts was 12.80 μg g^-1, an order of magnitude lower than in the roots. At low CIP concentrations, the highest leaf bioconcentration factor (LCF) and transfer factor (TF) indicated highly efficient translocation from roots to aerial parts. The soluble protein growth rate of leaves, which is associated with metabolic activity, increased following CIP exposure. Overall, eight major transformation products in E. crassipes tissues were identified, and three possible transformation pathways were proposed involving the processes of desethylation, dehydroxylation, oxidation, hydroxylation and cleavage of the piperazine and quinoline rings. These findings could prove beneficial for improving the management or amelioration methods used for treating water contaminated with antibiotics.

Bacteria-assisted removal of fluoroquinolones from wheat rhizospheres in an agricultural soil

Extensive fluoroquinolone antibiotics use results in their widespread occurrence in various environments including soil, which threatens the soil ecology and public health. The fate of fluoroquinolones in agricultural soil and the efficacy of enhanced degradation in the presence of an agricultural crops and antibiotic degrading bacteria could be better understood. The current study examined ciprofloxacin (CIP), enrofloxacin (ENR), and levofloxacin (LEV) biodegradation in a Maury Silt Loam soil in greenhouse conditions by bacterial-assisted removal of individual and mixed antibiotics in wheat rhizospheres. Fluoroquinolones were added at rates of 5, 50, and 100 mg kg^-1. Three bacterial isolates were applied at 10⁶ CFU g^-1 soil individually and in consortium. Antibiotics appeared in wheat tissue, with more accumulation in roots than shoots. Low recoveries (<50%) of CIP, ENR, and LEV were observed at all levels and treatments in a bacteria and wheat-free control compared to the initial concentrations applied Contaminated soil with wheat had greater antibiotic recovery than the wheat-free control. Antibiotic recovery with bacterial inoculum was less than that of the indigenous bacteria. The least antibiotic recovery occurred with wheat and bacterial inoculum together. At concentrations of 5 and 50 mg kg^-1, but not at 100 mg kg^-1, CIP, ENR, and LEV were below detection limits in soil after 30 days through the combination of wheat and bacteria compared to the control. This synergistic removal of the fluoroquinolone antibiotics is proposed to be due to enhanced antibiotic bioavailability, which suggests it as an environment-friendly approach to biodegradation.

Influence of the root plaque formation with different species on oxytetracycline accumulation in rice (Oryza sativa L.) and its elimination in culture solution

Hydroponic experiments were conducted to investigate the role of different root plaque formation on oxytetracycline (OTC) uptake/translocation by rice seedlings (Oryza sativa L.) and solution-OTC elimination at two initial OTC concentrations (10 and 30 mg L^-1). The results indicated OTC accumulation in rice was always in the order root surface > shoot > inside root whether plaques were formed or not. It demonstrated that Fe-Mn-Mt (montmorillonite) treatment was easier to promote significantly (p < 0.05) OTC accumulation in the underground part (root surface and inside root) and decrease significantly (p < 0.05) OTC translocation from the root to the shoot in rice compared to no plaque treatments (CK), especially for OTC 30 mg L^-1 level with the lowest shoot-OTC accumulation in Fe-Mn-Mt treatment. Plaque treatments increased half-life of solution-OTC elimination in the order Fe-Mn-Mt > Fe-Mn > Fe > CK, which was caused mainly by OTC degradation from Fe²⁺-binding influence in solution, not by the enhancement of OTC accumulation on the root surface and inside root. And solution-OTC elimination increased with decreasing initial OTC concentrations, the drop of Fe²⁺ and the increment of Fe³⁺ and pH during the experiment. These findings are useful for reducing OTC accumulation and translocation in rice aboveground parts and eliminating OTC contamination in agricultural environment simultaneously through complicated plaque formation under higher OTC concentration exposure (30 mg L^-1) in the future design.

Reducing water use by alternate-furrow irrigation with livestock wastewater reduces antibiotic resistance gene abundance in the rhizosphere but not in the non-rhizosphere

Livestock wastewater is rich in nutrients but may contain antibiotics and antibiotic resistance genes (ARGs). Their discharge to watercourses or soil may result in proliferation of ARGs. Irrigation with wastewater appears to be the most feasible option of disposing of it. One efficient irrigation technology used in arid regions is alternate-furrow irrigation (AFI) by alternately drying part of the plant roots for a prolonged period to physiologically reduce transpiration without compromising yield. However, the extent to which AFI with wastewater influences the concentration of antibiotics and spread of ARGs in soil is poorly understood. The purpose of this paper is to investigate how AFI using swine wastewater alters antibiotic kinetics and ARGs abundance under different irrigation rates, using pepper as the model plant. We examined three AFI treatments using 50%, 65% and 80% of the amount of water employed in sufficient conventional furrow irrigation. Each treatment had a groundwater irrigation control. The results showed that antibiotic concentrations and relative ARGs abundance in the top 20 cm of soil did not increase with the irrigation amount, although they were higher than those in the groundwater-irrigated soils. The relative ARGs abundance in the soil was modulated by irrigation amount and reducing the irrigation amount in AFI reduced ARGs dispersion only in rhizosphere. When the soil moisture was close to field capacity, ARGs were more abundant in rhizosphere than in non-rhizosphere, possibly because the rhizosphere is rich in microbes and increasing antibiotic concentrations due to an increase in irrigation rate favors antibiotic-resistant microbiome in competing for substrates. These, however, were not mirrored in the relative ARGs abundance in the roots. These results have important implications as it revealed that reducing the input of antibiotics and ARGs into soil with AFI does not necessarily reduce ARGs proliferation.

Role of Bentonite on the Mobility of Antibiotic Resistance Genes, and Microbial Community in Oxytetracycline and Cadmium Contaminated Soil

The effects of bentonite (BT), a commonly used heavy metal deactivator, on the ARGs and microbial communities in soils and lettuce systems contaminated by heavy metals and antibiotics are unclear. A study was conducted to investigate the effect of BT on the mobility of antibiotic resistance genes in oxytetracycline and cadmium contaminated soil. Results showed that the addition of BT reduced the accumulation of OTC and ARGs in the soil and lettuce roots, but increased the abundance of ARGs in lettuce leaves, and increase the risk of human pathogenic bacteria (HPB) transferring to lettuce leaves. Redundancy analysis showed that environmental factors (OTC, H₂O, SOM, and pH) were the dominant factors that influence the distribution of ARGs and intI1. Network analysis showed that Proteobacteria and Bacteroidetes were the major host bacteria which caused changes in ARGs and intI1. There were significant positive correlations between ermX and ermQ, and a large number of HPB. The co-occurrence of intl1 with some ARGs (tetC, tetG, ermQ, sul1, and sul2), may threaten human health due to the dispersion of ARGs via horizontal gene transfer.

Uptake of pharmaceuticals by plants grown under hydroponic conditions and natural occurring plant species: A review

Sizeable amount of research has been conducted on the possible uptake of pharmaceuticals by plants from contaminated soil and water used for irrigation of crops. In most cases, pharmaceuticals are taken by roots and translocated into various tissues by transpiration and diffusion. Due to the plant uptake, the occurrence of pharmaceuticals in food sources such as vegetables is a public concern. Few review papers focusing on the uptake of pharmaceuticals, in particular antibiotics, and their translocation in plant tissues have been published. In the current review paper, the work conducted on the uptake of pharmaceuticals belonging to different therapeutic groups such as antibiotics, non-steroidal anti-inflammatory drugs, β-blockers and antiepileptics is reviewed. Such work includes the occurrence of pharmaceuticals in plants, translocation once taken by plants, toxicity studies as well as implications and future studies. Furthermore, the advantages and drawbacks associated with the detection and uptake of these pharmaceuticals by plants are discussed. In addition, the physico-chemical properties that could influence the plant uptake of pharmaceuticals are deliberated.

Intraspecific variability of ciprofloxacin accumulation, tolerance, and metabolism in Chinese flowering cabbage (Brassica parachinensis)

To investigate the mechanism of genotype differences in ciprofloxacin (CIP) accumulation, this study was designed to compare the tolerance and metabolic responses to CIP exposure between low (Cutai) and high (Sijiu) CIP-accumulation cultivars of Brassica parachinensis. Decreases in biomass and chlorophyll content were significantly greater (p < 0.05) and toxicities were more severe within cell ultrastructures of Cutai compared to Sijiu. A sequential growth test also revealed that Sijiu was more tolerant to CIP stress compared to Cutai. Meanwhile, significantly higher (p < 0.05) root parameters and higher areas of the stele and xylem may be responsible for the increased uptake and transport of CIP in Sijiu. Ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) analysis revealed that CIP was metabolized to three major metabolites by the hydroxylation and breakdown of the piperazinyl substituent in the CIP molecule. The enhanced metabolic transformation of CIP in Sijiu indicated a more efficient capacity to detoxify, which in turn favored an increased accumulation of CIP in this cultivar. Thus, the present study demonstrated that the stronger tolerance and metabolism of Sijiu to CIP were responsible for its high CIP accumulation, suggesting an evolutionary mechanism for adaptation to environmental stress.

Bioprocessing for elimination antibiotics and hormones from swine wastewater

Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes' removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater.

Fluoroquinolones (FQs) in the environment: A review on their abundance, sorption and toxicity in soil

The use of fluoroquinolones (FQs) antibiotics as therapeutic agents and growth promoters is increasing worldwide; however their extensive uses are also resulting in antibiotic resistance among world communities. FQs have also become one of the major contaminants in the waste water bodies, which are not even completely removed during the treatment processes. Furthermore, their abundance in agricultural resources, such as the irrigation water, the bio-solids and the livestock manure can also affect the soil micro-environment. These antibiotics in soil tend to interact in several different ways to affect soil flora and fauna. The current review endeavors to highlight the some critical aspects of FQs prevalence in the environment. The review presents a detailed discussion on the pathways and abundance of FQs in soil. The discussion further spans the issue of sorption and FQs transformation into the soil better understand of their behavior and their toxicity to soil flora and fauna.

The effect of iron plaque on uptake and translocation of norfloxacin in rice seedlings grown in paddy soil

Although the role of iron plaque on rice root surface has been investigated in recent years, its effect on antibiotic uptake remains uncertain. In the study, pot experiment was conducted to investigate the effect of iron plaque on uptake and translocation of norfloxacin (adding 10 and 50 mg·kg^-1 treatments) in rice seedlings grown in paddy soil. Iron plaque was induced by adding different amounts of Fe(II) in soil. The results showed that the presence of norfloxacin can decrease the amount of iron plaque induced. After rice with iron plaque induced, norfloxacin was mainly accumulated in iron plaque on root surface, followed by inside root, but its translocation from root to other rice tissues is not observed. Iron plaque played the role of a barrier for norfloxacin uptake into rice roots under high norfloxacin concentration of 50 mg·kg^-1, however not that under low concentration of 10 mg·kg^-1. And the barrier function was the most strongest with adding Fe(II) of 30 mg·kg^-1 as combined action of iron plaque and rhizosphere effect. Fluorescence microscope analysis showed that norfloxacin mainly distributed in the outside of root cell, which showed its translocation as apoplastic pathway in rice. Comparing with non-rhizosphere, more norfloxacin was accumulated in rhizosphere soil. Maybe, strong root oxidization (high Eh values) induced more iron oxide formation in rhizosphere and on root surface, which led to norfloxacin's mobility towards to rhizosphere through its strong adsorption of iron oxides and then promoted its uptake by rice on root surface.

Long-term wastewater irrigation of vegetables in real agricultural systems: Concentration of pharmaceuticals in soil, uptake and bioaccumulation in tomato fruits and human health risk assessment

Wastewater (WW) reuse for vegetable crops irrigation is regularly applied worldwide. Such a practice has been found to allow the uptake of pharmaceutical active compounds (PhACs) by plants and their subsequent entrance to the food web, representing an important alternative pathway for the exposure of humans to PhACs, with potential health implications. Herein we report the impacts of the long-term (three consecutive years) WW irrigation of a tomato crop with two differently treated effluents under real agricultural conditions, on (1) the soil concentration of selected PhACs (i.e. diclofenac, DCF; sulfamethoxazole, SMX; trimethoprim, TMP), (2) the bioaccumulation of these PhACs in tomato fruits, and (3) the human risks associated with the consumption of WW-irrigated fruits. Results revealed that the concentration of the studied PhACs in both the soil and tomato fruits varied depending on the qualitative characteristics of the treated effluent applied and the duration of WW irrigation. The PhAC with the highest soil concentration throughout the studied period was SMX (0.98 μg kg^-1), followed by TMP (0.62 μg kg^-1) and DCF (0.35 μg kg^-1). DCF was not found in tomato fruits harvested from WW-irrigated plants during the first year of the study. However, DCF displayed the highest fruit concentration (11.63 μg kg^-1) throughout the study (as a result of prolonged WW irrigation), followed by SMX (5.26 μg kg^-1) and TMP (3.40 μg kg^-1). The calculated fruit bioconcentration factors (BCF_F) were extremely high for DCF in the 2nd (108) and 3rd year (132) of the experimental period, with the respective values for SMX (0.5-5.4) and TMP (0.2-6.4) being significantly lower. The estimated threshold of toxicity concern (TTC) and hazard quotients (HQ) values revealed that the consumption of fruits harvested from tomato plants irrigated for long period with the WW applied for irrigation under field conditions in this study represent a de minimis risk to human health. However, more studies need to be performed in order to obtain more solid information on the safety of WW reuse for irrigation.

Impact of Veterinary Pharmaceuticals on the Agricultural Environment: A Re-inspection

The use of veterinary pharmaceuticals (VPs) is a result of growing animal production. Manure, a great crop fertilizer, contains a significant amount of VPs. The investigation of VPs in manure is prevalent, because of the potential risk for environmental organisms, as well as human health. A re-evaluation of the impact of veterinary pharmaceuticals on the agricultural environment is needed, even though several publications appear every year. The aim of this review was to collate the data from fields investigated for the presence of VPs as an inevitable component of manure. Data on VP concentrations in manure, soils, groundwater and plants were collected from the literature. All of this was connected with biotic and abiotic degradation, leaching and plant uptake. The data showed that the sorption of VPs into soil particles is a process which decreases the negative impact of VPs on the microbial community, the pollution of groundwater, and plant uptake. What was evident was that most of the data came from experiments conducted under conditions different from those in the environment, resulting in an overestimation of data (especially in the case of leaching). The general conclusion is that the application of manure on crop fields leads to a negligible risk for plants, bacteria, and finally humans, but in future every group of compounds needs to be investigated separately, because of the high divergence of properties.

Oxytetracycline Toxicity and Its Effect on Phytoremediation by Sedum plumbizincicola and Medicago sativa in Metal-Contaminated Soil

Excessive use of antibiotics potentially threatens human health, agricultural production, and soil phytoremediation. This arouses concern over the potential adverse effects of a commonly used antibiotic, oxytetracycline (OTC), on plants used for soil remediation and possible stimulation of antibiotic resistance genes in soils. A greenhouse experiment was conducted to investigate different rates (0, 1, 5, and 25 mg kg^-1) and frequencies (one single high and daily low application) of OTC addition to soil on phytoremediation of a heavy metal contaminated soil by Sedum plumbizincicola and/or Medicago sativa (alfalfa). After 90 days both Cd and Zn were substantially removed by phytoextraction into S. plumbizincicola shoots especially at the high OTC (25 mg kg^-1) treatment which also led to inhibition of antioxidative enzyme activities in both plant species. Soil microbial activity decreased significantly with the addition of OTC, and this was ameliorated by planting alfalfa and S. plumbizincicola together. OTC at <5 mg kg^-1 increased the biomass of both plant species, but the frequency of OTC addition had no effect on the rate of metal removal. Alfalfa exhibited greater detoxification ability and effectiveness in soil microbial activity promotion than S. plumbizincicola with intercropping. Phytoremediation by alfalfa and S. plumbizincicola in association can both promote the removal of heavy metals and also alleviate the toxic effects of pollutants on plants and soil microbes even at relatively high soil OTC concentrations.

Phytoremediation of aspirin and tetracycline by Brassica juncea

With the increasing release of pharmaceutical drugs in the environment, research is in progress for investigating alternative methods for their remediation. Various studies have shown the phytoremediation potential of Brassica juncea for metals. The current study was aimed at evaluating the phytoremediation potential of B. juncea for two different pharmaceutical drugs i.e. aspirin and tetracycline in in-vitro conditions. The seeds of B. juncea were germinated and grown for a period of 28 and 24 days for aspirin and tetracycline, respectively. The study analyzed the remediation rate of B. juncea for the selected drugs in three different sets of varying concentration along with any phytotoxic effects exerted by the drugs on the seeds. Preliminary results showed that the average remediation rate of aspirin and tetracycline at the end of experiment was approximately 90% and 71%, respectively. As initial drug concentrations were increased in the media, the remediation rate also improved. However, at higher concentrations, the plants showed phytotoxicity as depicted by the decrease in shoot length of the germinated seeds. These preliminary results indicated that B. juncea could tolerate and remediate pharmaceutical drugs such as analgesics and antibiotics.

Variations in the fate and biological effects of sulfamethoxazole, norfloxacin and doxycycline in different vegetable-soil systems following manure application

The fate of sulfamethoxazole (SMZ), norfloxacin (NOR) and doxycycline (DOX) and their biological effects in radish and pakchoi culture systems were investigated. DOX dissipated more rapidly than SMZ and NOR, while radish and pakchoi cultivation increased the removal of residual DOX in soils. Dissipation of NOR was accelerated in radish soils but was slowed down slightly in pakchoi soils. Vegetable cultivation exerted an insignificant effect on SMZ removal. Investigation of antibiotic bioaccumulation showed that the uptake of DOX by radish and pakchoi was undetectable, but the radish accumulated more SMZ and NOR than pakchoi. Among the three antibiotics, only SMZ use exhibited an apparent suspension of plant seed germination, up-ground plant growth and soil microbial diversity. Pakchoi responded more sensitively to SMZ than did the radish. Principal component analysis (PCA) based on MicroRESP™ indicated that the sampling time and antibiotic treatments could influence the soil microbial community. Only in the pakchoi soils did antibiotic application exert a more robust effect on the microbial community than the sampling time; SMZ treatments and DOX treatments could be clearly discriminated from the control treatments. These results are crucial for an assessment of the potential risks of antibiotics to culture system practices and suggest that good agricultural practices help to limit or even reduce antibiotic pollution.

Root Uptake of Pharmaceuticals and Personal Care Product Ingredients

Crops irrigated with reclaimed wastewater or grown in biosolids-amended soils may take up pharmaceuticals and personal care product ingredients (PPCPs) through their roots. The uptake pathways followed by PPCPs and the propensity for these compounds to bioaccumulate in food crops are still not well understood. In this critical review, we discuss processes expected to influence root uptake of PPCPs, evaluate current literature on uptake of PPCPs, assess models for predicting plant uptake of these compounds, and provide recommendations for future research, highlighting processes warranting study that hold promise for improving mechanistic understanding of plant uptake of PPCPs. We find that many processes that are expected to influence PPCP uptake and accumulation have received little study, particularly rhizosphere interactions, in planta transformations, and physicochemical properties beyond lipophilicity (as measured by Kow). Data gaps and discrepancies in methodology and reporting have so far hindered development of models that accurately predict plant uptake of PPCPs. Topics warranting investigation in future research include the influence of rhizosphere processes on uptake, determining mechanisms of uptake and accumulation, in planta transformations, the effects of PPCPs on plants, and the development of predictive models.

Removal of pharmaceutically active compounds (PhACs) and toxicological response of Cyperus alternifolius exposed to PhACs in microcosm constructed wetlands

This study investigated the effects of selected four pharmaceutically active compounds (PhACs) (carbamazepine, sulfamethoxazole, ofloxacin, and roxithromycin) on the photosynthesis and antioxidant enzymes of Cyperus alternifolius in constructed wetlands (CWs). Moreover, the removal and kinetics of PhACs in CWs were evaluated to explore the related removal mechanisms. Results showed that C. alternifolius can uptake and withstand certain PhACs. The PhAC tolerance of C. alternifolius might be attributed to their capacity to maintain relatively normal photosynthetic activity and elevated antioxidative defense. CWs offered comparable or even higher removal efficiencies for the selected PhACs compared with conventional WWTPs. The removal of the target PhACs was enhanced in the planted CWs versus the unplanted CWs mostly because of plant uptake and rhizosphere effects. In particular, carbamazepine, which is considered the most recalcitrant of the PhACs, was significantly reduced (p<0.05). The removal of target PhACs fitted into two distinct periods. The initial fast step (within the first 2 h) was essentially attributed to the adsorption onto the CW medium surface. The subsequent slow process (2-12 h) closely followed first-order kinetics probably because of the interaction between microorganisms and plants. The obtained results indicate that C. alternifolius can phytoremediate PhAC-contaminated waters in CWs.

Transfer of oxytetracycline from swine manure to three different aquatic plants: implications for human exposure

Little is known regarding the potential for pharmaceuticals including antibiotics to be accumulated in edible aquatic plants and enter the human food chain. This work investigates the transfer of a widely used veterinary antibiotic, oxytetracycline (OTC), from swine manure to aquatic plants by firstly characterizing desorption from swine manure to water and fitting data to both nonlinear and linear isotherms. Bioconcentration of OTC from water was then quantified with aquatic plants of contrasting morphology and growth habit viz. watermeal (Wolffia globosa Hartog and Plas), cabomba (Cabomba caroliniana A. Gray) and water spinach (Ipomoea aquatica Forsk.). Watermeal and water spinach are widely consumed in Southeast Asia. The OTC desorption and bioconcentration data were used to provide the first quantitative estimates of human exposure to OTC from a manure-water-aquatic plant route. Results show that under certain conditions (plants growing for 15d in undiluted swine manure effluent (2% w/v solids) and an initial OTC swine manure concentration of 43mgkg(-1) (dry weight)), this pathway could provide a significant fraction (>48%) of the acceptable daily intake (ADI) for OTC. While effluent dilution, lower OTC manure concentrations and not all plant material consumed being contaminated would be expected to diminish the proportion of the ADI accumulated, uptake from aquatic plants should not be ignored when determining human exposure to antibiotics such as OTC.

Evaluation of biological endpoints in crop plants after exposure to non-steroidal anti-inflammatory drugs (NSAIDs): implications for phytotoxicological assessment of novel contaminants

Human pharmaceuticals have been detected in the terrestrial environment at µg to mg kg(-1) concentrations. Repeated application of sewage sludge (biosolids) and increasing reclaimed wastewater use for irrigation could lead to accumulation of these novel contaminants in soil systems. Despite this, potential phytotoxicological effects on higher plants have rarely been evaluated. These studies aimed to test effects upon germination, development, growth and physiology of two crop plants, namely radish (Raphanus sativus Spakler 3) and lettuce (Lactuca sativa All Year Around), after exposure to different, but structurally related non-steroidal anti-inflammatory drugs (NSAIDs) at environmentally relevant concentrations. A range of biological endpoints comprising biomass, length, water content, specific root and shoot length, root to shoot ratio, daily progress of stages of cell elongation and organ emergence (primary root, hypocotyl elongation, cotyledon emergence, cotyledon opening, and no change), as well as photosynthetic measurements were evaluated. Compounds from the fenamic acid class were found to affect R. sativus root endpoints (root length and water content), while ibuprofen affected early root development of L. sativa. In general, phytotoxicological effects on root endpoints demonstrated that impacts upon higher plants are not only compound specific, but also differ between plant species. It was found that the usage of a wide range of biological endpoints (all simple, cost-effective and ecologically relevant) were beneficial in detecting differences in plant responses to NSAID exposure. Due to paucity and discrepancy within the few previously available phytotoxicological studies with pharmaceuticals, it is now essential to allocate time and resources to consider development of suitable chronic toxicity tests, and some suggestions regarding this are presented.

Potential of Pteris vittata to Remove Tetracycline Antibiotics from Aquatic Media

The role of combined arsenic and antibiotics pollution in the environment has recently gained more attention. In this study, a new approach to eliminate tetracycline antibiotics (TCs) from water, via the fern species Pteris vittata (L.), an arsenic hyperaccumulator, was investigated. The encouraging results showed that more than half of the TCs could be removed from the water solution (with the starting concentration of TCs about 1.0 mg kg(-1) respectively) after one day of treatment. No TCs (less than 0.01 mg kg(-1)) were detected in the solution after five days of treatment. The results showed that Pteris vittata has high ability to eliminate TCs, which makes it suitable for practical application. Further research found that TCs concentrations were very low in both the roots and the pinnae of Pteris vittata, which indicates that accumulation in the fronds is not the main removal mechanism and that degradation in the fronds might be the main cause. Present results provide a feasible method for simultaneous removal of arsenic and TCs from livestock-polluted wastewater. However, more research work should be done before any real-world application is made.

Temporal changes in horsebean bioavailability and accumulation after removing extractable oxytetracycline fractions in soils

Extractable fractions of oxytetracycline in soil affect its bioavailability and accumulation in plants.

A review of plant-pharmaceutical interactions: from uptake and effects in crop plants to phytoremediation in constructed wetlands

Pharmaceuticals are commonly found both in the aquatic and the agricultural environments as a consequence of the human activities and associated discharge of wastewater effluents to the environment. The utilization of treated effluent for crop irrigation, along with land application of manure and biosolids, accelerates the introduction of these compounds into arable lands and crops. Despite the low concentrations of pharmaceuticals usually found, the continuous introduction into the environment from different pathways makes them 'pseudo-persistent'. Several reviews have been published regarding the potential impact of veterinary and human pharmaceuticals on arable land. However, plant uptake as well as phytotoxicity data are scarcely studied. Simultaneously, phytoremediation as a tool for pharmaceutical removal from soils, sediments and water is starting to be researched, with promising results. This review gives an in-depth overview of the phytotoxicity of pharmaceuticals, their uptake and their removal by plants. The aim of the current work was to map the present knowledge concerning pharmaceutical interactions with plants in terms of uptake and the use of plant-based systems for phytoremediation purposes.

Sorption and solubility of ofloxacin and norfloxacin in water-methanol cosolvent

Prediction of the properties and behavior of antibiotics is important for their risk assessment and pollution control. Theoretical calculation was incorporated in our experimental study to investigate the sorption of ofloxacin (OFL) and norfloxacin (NOR) on carbon nanotubes and their solubilities in water, methanol, and their mixture. Sorption for OFL and NOR decreased as methanol volume fractions (fc) increased. But the log-linear cosolvency model could not be applied as a general model to describe the cosolvent effect on OFL and NOR sorption. We computed the bond lengths of possible hydrogen bonds between solute and solvent and the corresponding interaction energies using Density Functional Theory. The decreased OFL solubility with increased fc could be attributed to the generally stronger hydrogen bond between OFL and H2O than that between OFL and CH3OH. Solubility of NOR varied nonmonotonically with increasing fc, which may be understood from the stronger hydrogen bond of NOR-CH3OH than NOR-H2O at two important sites (-O18 and -O21). The interaction energies were also calculated for the solute surrounded by solvent molecules at all the possible hydrogen bond sites, but it did not match the solubility variations with fc for both chemicals. The difference between the simulated and real systems was discussed. Similar sorption but different solubility of NOR and OFL from water-methanol cosolvent suggested that sorbate-solvent interaction seems not control their sorption.

Uptake of zwitterionic antibiotics by rice (Oryza sativa L.) in contaminated soil

Antibiotics, including members of the tetracycline and fluoroquinolone families, are emerging organic environmental contaminants. Uptake from soil by plants is a means for antibiotics to enter terrestrial food chains. Chemical exchange between plant and the soil/water matrix occurs simultaneously with degradation in the soil/water matrix. In this study, the comparative temporal behaviour of rice (Oryza sativa L.) towards the zwitterionic antibiotics oxytetracycline, chlortetracycline and norfloxacin at initial soil/water concentrations of 10, 20 and 30 μg g(-1) (dry weight) is investigated. This is accomplished within the framework of an activity-based mass-conserving dynamic model. Plant antibiotic concentrations are observed to increase to a maximum then decline. Maximum concentrations in rice are compound-dependent linear functions of initial soil/water concentrations, but the relationships are not related to the compound octan-1-ol/water distribution ratio (DOW). The times required to attain maximal concentrations are independent of initial soil/water levels for a given antibiotic, but again vary between antibiotics and are not related to DOW values. Translocation from root to other tissues is not observed. The magnitudes of Root Concentration Factors (RCFs), the ratio of root and soil/water concentrations, are consistent with significant sorption to soil and consequent relatively low concentrations in interstitial water.

Evaluation of food chain transfer of the antibiotic oxytetracycline and human risk assessment

There has been recent concern regarding the possibility of antibiotics entering the aquatic food chain and impacting human consumers. This work reports experimental results of the bioconcentration of the antibiotic oxytetracycline (OTC) by the Asian watermeal plant (Wolffia globosa Hartog & Plas) and bioaccumulation of OTC in watermeal and water by the seven-striped carp (Probarbus jullieni). They show, for the first time, the extent to which OTC is able to transfer from water to plant to fish and enter the food chain. The mean bioconcentration factor (dry weight basis) with watermeal was 1.28 × 10(3) L kg(-1). Separate experiments were undertaken to characterize accumulation of OTC by carp from water and watermeal. These showed the latter pathway to be dominant under the conditions employed. The bioconcentration and biomagnification factors for these processes were 1.75 L kg(-1) and 2 × 10(-4) kg g(-1) respectively. Using an aqueous concentration range of 0.34-3.0 μg L(-1), hazard quotients for human consumption of contaminated fish of 1.3 × 10(-2) to 1.15 × 10(-1) were derived.

Elimination of veterinary antibiotics and antibiotic resistance genes from swine wastewater in the vertical flow constructed wetlands

This paper investigated the efficiency of two vertical flow constructed wetlands characterized by volcanic (CW1) and zeolite (CW2) respectively, at removing three common antibiotics (ciprofloxacin HCl, oxytetracycline HCl, and sulfamethazine) and tetracycline resistance (tet) genes (tetM, tetO, and tetW) from swine wastewater. The result indicated that the two systems could significantly reduce the wastewater antibiotics content, and elimination rates were in the following sequence: oxytetracycline HCl>ciprofloxacin HCl>sulfamethazine. The zeolite-medium system was superior to that of the volcanic-medium system vis-à-vis removal, perhaps because of the differing pH values and average pore sizes of the respective media. A higher concentration of antibiotics accumulated in the soil than in the media and vegetation, indicating that soil plays the main role in antibiotics removal from wastewater in vertical flow constructed wetlands. The characteristics of the wetland medium may also affect the antibiotic resistance gene removal capability of the system; the total absolute abundances of three tet genes and of 16S rRNA were reduced by 50% in CW1, and by almost one order of magnitude in CW2. However, the relative abundances of target tet genes tended to increase following CW1 treatment.

Phytoremediation potential of vetiver grass [Chrysopogon zizanioides (L.)] for tetracycline

The presence of veterinary and human antibiotics in soil and surface water is an emerging environmental concern. The current study was aimed at evaluating the potential of using vetiver grass as a phytoremediation agent in removing Tetracycline (TC) from aqueous media. The study determined uptake, translocation, and transformation of TC in vetiver grass as function of initial antibiotic concentrations and exposure time. Vetiver plants were grown for 60 days in a greenhouse in TC contaminated hydroponic system. Preliminary results show that complete removal of tetracycline occurred within 40 days in all TC treatments. Initial concentrations of TC had significant effect (p < 0.0001) on the kinetics of removaL Tetracycline was detected in the root as well as shoot tissues, confirming uptake and root-to-shoot translocation. Liquid-chromatography-tandem-mass-spectrometry analysis of plant tissue samples suggest presence of metabolites of TC in both root and shoot tissues of vetiver grass. The current data is encouraging and is expected to aid in developing a cost-effective, in-situ phytoremediation technique to remove TC group of antibiotics from wastewater.

A preliminary study on the phytoremediation of antibiotic contaminated sediment

In Vietnam's coastal wetlands, fluoroquinolones, a widely used class of antibiotics in shrimp farming, are frequently detected in sediments of former shrimp farms. This phenomenon could lead to negative impacts on the aquatic ecosystem, since the antibiotic residues could induce changes in the microorganism communities of the water body. The potential of native wetland plants (Acrostichum aureum L. and Rhizophora apiculata Blume Fl. Javae) for phytoremediation of fluoroquinolones (ciprofloxacin and norfloxacin) was investigated. The half-life for each antibiotic was estimated at approximately 10 days in the planted sediment. With respect to the accumulation of ciprofloxacin and norfloxacin in plants, these antibiotics were found mainly in roots. Antibiotic translocation from root to stem and leaves occurred at a low rate. The results showed that A. aureum and R. apiculata can be valuable for the phytoremediation of antibiotic-contaminated sediments. Additionally, the initialfindings of the presence of resistant bacteria indicated that bacteria could play a role in facilitating the phytodegradation.

Adsorption of ofloxacin and norfloxacin on carbon nanotubes: hydrophobicity- and structure-controlled process

Adsorption of antibiotics on solid particles is a key process controlling their fate in the subsurface. This study compared the adsorption of ofloxacin and norfloxacin (NOR) on carbon nanotubes (CNTs) to evaluate the role of structural and hydrophobic properties in regulating their adsorption. A significant relationship was observed between single-point adsorption coefficients (K(d)) and specific surface area (highly hydrophobic), but not between K(d)s and oxygen content. This result suggested that site-specific adsorption was not important but hydrophobic effect may have an important contribution to OFL and NOR adsorption on CNTs. However, normalizing the adsorption coefficients by OFL and NOR solubilities enlarged their adsorption difference indicating that hydrophobicity was not the only factor controlling the difference between OFL and NOR adsorption on CNTs. Their chemical structures show that both chemicals could interact with CNTs through an electron-donor-acceptor mechanism. This mechanism was correlated with the different adsorption of OFL and NOR on functionalized CNTs (namely hydroxylized, carboxylized, and graphitized CNTs). This study revealed that OFL and NOR adsorption was controlled by their both structural- and hydrophobic-properties.

Green pharmacy and pharmEcovigilance: prescribing and the planet

Active pharmaceutical ingredients (APIs) are ubiquitous environmental contaminants, resulting primarily from excretion and bathing and from disposal of leftover drugs by consumers and healthcare facilities. Although prudent disposal of leftover drugs has attracted the most attention for reducing API levels in the aquatic environment, a more effective approach would prevent the generation of leftover drugs in the first place. Many aspects of the practice of medicine and pharmacy can be targeted for reducing environmental contamination by APIs. These same modifications--focused on treating humans and the environment as a single, integral patient--could also have collateral outcomes with improved therapeutic outcomes, and with a reduced incidence of unintended poisonings, drug interactions and drug diversion, and lower consumer costs.

Investigation of the mechanism of uptake and accumulation of zwitterionic tetracyclines by rice (Oryza sativa L.)

The uptake and accumulation of organic contaminants by plants can be detrimental to the plant itself as well as consumers. Tetracycline antibiotics are present at trace levels in soil and water. Under typical environmental conditions, they exist as zwitterions. Comparatively little is known of their uptake and accumulation by plants, or the mechanism by which this occurs. To examine this, rice (Oryza sativa L.) was employed, together with a static diffusion cell equipped with a cellulose membrane as a model for the uptake process. For rice, kinetic results suggested that the zwitterions were behaving similarly to neutral organic compounds, with a passive uptake process. The diffusion cell provided qualitatively similar results. When exposed to aqueous concentrations of zwitterionic tetracyclines of 50 mg L(-1) over 15 days, no translocation to shoots or detrimental effects on plants was observed. Despite relatively low root lipid contents, concentrations in root tissue of greater than 1000 mg kg(-1) (d.w.) were determined with maximum Root Concentration Factors of the order of 2000 L kg(-1) (d.w.). Overall, for the tetracyclines investigated, kinetic and accumulation behavior in plants together with permeation in the diffusion cell were all governed by compound hydrophobicity.

Accumulation and effects of sulfadimethoxine in Salix fragilis L. plants: a preliminary study to phytoremediation purposes

The application of manure to fertilize arable lands is one of the major means through which veterinary sulfonamides (SAs) enter the environment. Little is known about the capacity of woody plants to phytoremediate this class of antibiotics. To this purpose we performed preliminary studies to evaluate Salix fragilis L. response to sulfadimethoxine (SDM) by investigating both its ability to absorb and tolerate doses of SDM found in fresh faeces of treated calves. Forty cuttings were exposed to either 0, 0.5, 1, or 2 mM of SDM for one month. Decreases in photosynthetic electron transport rate and net CO2 assimilation after 25 days for the higher SDM concentrations were noticed. Moreover, alterations in root morphology of treated plants were observed and further investigated through electron microscopy. However, collected data revealed high root accumulation potential. These preliminary results are promising as they demonstrate that Salix fragilis L. can both absorb and tolerate high concentrations of SAs.