Residues In Aquatic Environment Research Articles

Chiral pesticides levels in peri-urban area near Yangtze River and their correlations with water quality and microbial communities.

Pesticides are considered to be the second-largest non-point source pollution in water. Our research assayed the river network of typical agricultural areas in the middle and lower Yangtze River as the study area. Pesticides residues in aquatic environment were determined by QuEChERS, combined with high-performance liquid chromatography tandem mass spectrometry, or gas chromatograph-mass spectrometer. At chiral pesticides' levels, we detected pesticides contents in water, classified and counted the types of pesticides, and analyzed their environmental risk assessment. Furthermore, potential correlations between chiral pesticides concentrations and water quality indicators were assayed. Additionally, we explored their relations with microbial communities at species levels. Enantiomers of Diclofop-methyl, Ethiprole, Difenoconazole and Epoxiconazole were enantioselectively distributed. More interestingly, due to various chiral environment of the sampling site, the enantiomers of Tebuconazole Acetochlor, Glufosinate ammonium and Bifenthrin had completely different distributions at different sites. Based on that, the chiral pesticides Diclofop-methyl, Bifenthrin, Ethiprole, Tebuconazole and Difenoconazole are enantioselective to the risk of aquatic environment. Generally, enantiomeric selectivity had high positive correlations with total nitrogen and phosphorus. Then we found that chiral fate behavior of Tebuconazole and Paichongding in water might be affected by prokaryotes. In addition, the chiral behavior of Diclofop-methyl, Propiconazole, Difenoconazole, and Tebuconazole isomers in water might be negatively affected by eukaryotes. That research helped us to comprehensively understand the impact of non-point source pollution of chiral pesticides in aquatic environment and provided basic data support for developing biological and water quality indicators for monitoring pollution in aquatic environment.

Photoelectrocatalytic degradation of sulphonamide antibiotics in aquatic media using a novel Co-doped ZnO nanocomposite: evaluation of performance, kinetic studies

ABSTRACT It is well known that antibiotics’ residues in aquatic environments are a great threat to human health and ecology. Thus, it is vital to develop efficient strategies to overcome the mentioned threat and degrade the pointed out residues as much as possible. Herein, a novel Co-doped ZnO nanocomposite was fabricated and deposited on fluorine-doped tin oxide glass sheets (FTO) and eventually applied for the photoelectrocatalytic degradation of four sulphonamides (SAs), namely sulphacetamide (SCT), sulphathiazole (STZ), sulfamethoxazole (SMX) and sulphadiazine (SDZ) under visible light irradiation. In this regard, the effect of initial pH (3–11), applied current (0.5–1.5 mA/cm2), initial concentration of SAs (5–20 mg/L) were thoroughly investigated. The results indicated that under the optimal conditions (pH = 9, [SAs] = 5 mg/L and applied current = 1.5 mA/cm2), the degradation efficiencies obtained under a 90-min of reaction time were as follows: SCT (97.1%), SMX (95.8%), SDZ (93.2%) and STZ (91.8%). In addition, the degradation of the SAs by the applied photoelectrocatalytic process (PECP) followed the first-order kinetic model. Meanwhile, the applied PECP exhibited an excellent performance with regard to real samples. Finally, PECP is reckoned to be associated with ‘green’ technologies as electricity is involved and the used catalyst will not end up in the environment as secondary toxic materials.

Enhanced photoelectrochemical aptasensing triggered by nitrogen deficiency and cyano group simultaneously engineered 2D carbon nitride for sensitively monitoring atrazine

Determination of atrazine (ATZ) residues in aquatic environment has important theoretical and practical significance for protecting the ecological environment and ensuring human health. A photoelectrochemical (PEC) aptasensing based on nitrogen deficiency and cyano group simultaneously engineered two-dimensional (2D) carbon nitride (named as DCN) has been proposed for sensitively detecting ATZ. The introduction of nitrogen deficiency can narrow band gap of DCN, leading to positive position of intermediate electronic state, and improving the absorption of visible light. The intermediate electronic state can function as an electron trap to promote the separation and migration of photogenerated carriers. Cyano groups can trap photoinduced electrons and suppress charge recombination. Gas produced by thermal decomposition has a tailoring effect, endowing DCN with 2D ultra-thin structure, which shortens transmission path of carriers. The synergistic effect of the above enhances PEC performance of DCN. The PEC aptasensing exhibited a wide linear range of 1.0 × 10−4 to 1.0 × 103 pM and a low detection limit of 3.33 × 10−5 pM with excellent selectivity, stability, and satisfactory accuracy during detecting real samples. The proposed design of carbon nitride-based materials may provide a better understanding of the relationship between kind of photoactive materials and PEC performance.

Effect of g-C3N4 on biodiversity and structure of bacterial community in sediment of Xiangjiang River under tetracycline pressure.

Photocatalysts have been widely prepared and used in wastewater treatment. Although the influence of photocatalyst application on survival and activity of organisms has been examined, its impact on composition and diversity of microbial community is not fully understood. In this study, the impact of photocatalyst g-C3N4 (Graphitic carbon nitride) on microbial communities in riverbed sediments polluted by antibiotic tetracycline (TC) was investigated. The sediment samples collected from the Xiangjiang River of China were exposed to different concentrations of TC, g-C3N4 and TC/g-C3N4 and the bacterial community were analyzed by Illumina sequencing. The results showed that the dominant bacterial phyla were Acidobacteriota, Proteobacteria, Actinobacteriota, and Chloroflexi in the study site. When compared to the control treatments, the application of TC, g-C3N4 and TC/g-C3N4 exhibited distinguishable effects on bacterial community structure in sediments. The presence of TC had greater influence on bacterial composition, while g-C3N4 and TC/g-C3N4 had less influence on bacteria. The diversity and richness of microorganisms in sediment increased under g-C3N4 application and reached the highest values when g-C3N4 was 75 mg/kg. The photocatalyst g-C3N4 restored bacterial community diversity affected by TC, reduced the TC residues in aquatic environment, and eliminated the side effects of TC application in sediments. Our study indicated that g-C3N4 was an environmentally friendly photocatalyst with lightly negative effects on microbial community in riverbed sediments, and could be used for effective remediation of TC-contaminated environments.

Simultaneous degradation of amoxicillin and norfloxacin by TiO2@nZVI composites coupling with persulfate: Synergistic effect, products and mechanism

• Persulfate (PS) significantly enhanced AMX removal by TiO 2 @nZVI/UV process. • The decomposition rate of PS in TiO 2 @nZVI/PS/UV process was the highest. • Both HO• and SO 4 •− were the dominant radicals in TiO 2 @nZVI/PS/UV process. • AMX was effectively degraded through hydroxylation and deamination reactions. • A mechanism for the simultaneous removals of AMX and NOF was proposed. In recent years, a serious threat of antibiotic residues in aquatic environments to human health and ecological security has become increasingly widespread attention. In this study, this is the first report on an alternative strategy on enhanced degradation of amoxicillin (AMX) and norfloxacin (NOF) by TiO 2 @nZVI/persulfate (PS) process under UV irradiation. Results revealed that a signficantly synergistic effect on AMX degradation had been achieved in TiO 2 @nZVI/PS/UV process due to the photocatalysis and Fenton-like reactions. NO 3 – , HCO 3 – , PO 4 3- and humic acid exhibited inhibitory effects on AMX degradation, whereas Cl - was negligible on that. The degradation of AMX decreased as the addition of Cr(VI) concentrations increased, whereas the correspond values were enhanced when a low Cu(II) concentration was introduced. TiO 2 @nZVI/PS/UV process was the most efficient for activating PS decomposition. HO•, SO 4 •− and 1 O 2 were all generated in TiO 2 @nZVI/PS/UV process, but HO• and SO 4 •− were the dominant radical species for AMX degradation. The AMX intermediates products identified by LC-MS system confirmed AMX was effectively degraded through hydroxylation and deamination reactions. A better performance on the simultaneous removals of AMX and NOF by TiO 2 @nZVI/PS/UV process could be achieved at lower concentration conditions, and the simultaneous reaction mechanism was thereby proposed base on expriment results.

Lanthanide metal-organic framework as a paper strip sensor for visual detection of sulfonamide with smartphone-based point-of-care platform

Antibiotic residues in aquatic environments have attracted wide attention. Considering the impacts on the ecosystem and human health, it is urgent to develop a rapid method for detecting antibiotic residues in the environment. In this work, a nanoscale lanthanide metal-organic framework Eu(TATB) with a stable red luminescence in aqueous solution is synthesized by the microemulsion method. Sulfamethazine (SMZ) is frequently most used in veterinary medicine as one of sulfonamides. Eu(TATB) can be used for sensitively and rapidly specific recognition of SMZ with low detection limit (0.67 μM) and eminent recyclability. In addition, a paper-based visual system for point-of-care (POC) monitoring SMZ is devised by both using filter paper embedded with Eu(TATB) and our developed portable smartphone-involved imaging cassette. The naked eyes can observe that the red luminescence of the paper sensor gradually fades away at the presence of SMZ. This provides a reliable and effective method for on-site detection of sulfonamide antibiotics in the field of environmental monitoring.

Effects of florfenicol on growth, photosynthesis and antioxidant system of the non-target organism Isochrysis galbana

Florfenicol (FFC) is one of the most universally used antibiotics in aquaculture, which is substitute for chloramphenicol extensively, while the massive residues in aquatic environment were assumed to threaten the non-target organisms. Present research investigated the effects of florfenicol on growth, chlorophyll content, photosynthesis, and antioxidant ability of Isochrysis galbana. The results showed that FFC at 0.001–1 mg/L stimulated the growth of I. galbana and increased the content of chlorophyll. In addition, photosynthesis of I. galbana was inhibited and the photosynthetic parameters were uplifted with the increased exposure duration and FFC concentration. Furthermore, superoxide dismutase (SOD), catalase (CAT) activity significantly dropped at 0.01–20 mg/L FFC, while the contents of malondialdehyde (MDA), glutathione (GSH) and reactive oxygen species (ROS) increased after 72 h exposure, indicating that FFC at high concentrations caused a serious oxidative stress on algae. The simultaneous increase of ROS disrupted the equilibration between oxidants and antioxidant systems. Under the high concentration of FFC, the excessive of ROS was generated in algae which affected the membrane permeability and further decreased the cell biomass. Present study showed that acute exposure (72 h) at the environmental relevant concentration (0.01 mg/L) cannot induce the physiological dysfunction of the microalgae I. galbana, but the feeding concentration (20 mg/L) can. Additionally, this study hinted the possible negative impacts on ecosystems with the chronic exposure even at low FFC concentration or with the uncontrolled use of FFC.

Effective Elimination of Contaminant Antibiotics Using High-Surface-Area Magnetic-Functionalized Graphene Nanocomposites Developed from Plastic Waste.

The presence of pharmaceutical residues in aquatic environments represents a risk for the equilibrium of the ecosystem and may seriously affect human safety itself in the long term. To address this issue, we have synthesized functional materials based on highly-reduced graphene oxide (HRGO), sulfonated graphene (SG), and magnetic sulfonated graphene (MSG). The method of synthesis adopted is simple and inexpensive and makes use of plastic bottle waste as the raw material. We have tested the fabricated materials for their adsorption efficiency against two model antibiotics in aqueous solutions, namely Garamycin and Ampicillin. Our tests involved the optimization of different experimental parameters of the adsorption process, such as starting antibiotic concentration, amount of adsorbent, and time. Finally, we characterized the effect of the antibiotic adsorption process on common living organisms, namely Escherichia coli DH5α (E. coli DH5α) bacteria. The results obtained demonstrate the efficiency of the method in addressing the issue of the emergence of antibiotic-resistant bacteria, which will help in preventing changes in the ecosystem.

Synthesis of Molecularly Imprinted Polymers for the Selective Extraction of Polymyxins from Environmental Water Samples.

The emergence of colistin resistance gen has aroused public concern. It is significant to assess the concentrations of polymyxins residues in aquatic environment since resistant bacteria carrying colistin resistance gen are frequently isolated from wastewater; surface water and ground water. However; no literature on the determination of polymyxins in water is available; probably due to the absence of an efficient extraction method. Accordingly; molecularly imprinted polymers were synthesized by precipitation polymerization with colistin as the template. The polymers were successfully used as sorbents for the determination of polymyxins from water based on molecularly imprinted solid-phase extraction and high-performance liquid chromatography–ultraviolet detection. The molecularly imprinted cartridge showed excellent affinity and cross-reactivity to analytes in aqueous media. Recoveries obtained from water samples were between 65.9% and 90.1%, with relative standard deviations lower than 10.2%. Limits of detection were between 1.0 and 2.0 μg L−1 concentration levels. Compared with C18 cartridge; the molecularly imprinted cartridge could remove more interference from co-extracted matrices. This method is practical for the routine monitoring of polymyxin residues in environmental water; which will benefit studies on drug-resistance and occurrence of polymyxins in the environment.

Simultaneous enhancements of light-harvesting and charge transfer in UiO-67/CdS/rGO composites toward ofloxacin photo-degradation

Antibiotics residues in aquatic environments has aroused great public concern since they cannot be effectively removed by conventional biological degradation. Sunlight-driven photo-degradation has been recognized as one of most efficient approach for the antibiotics removal. Herein, we proposed a novel strategy of simultaneous light-harvesting and electron-relay-penetration for the photocatalytic degradation of target antibiotics of ofloxacin (OFL). By incorporating visible-light responded semiconductor CdS nanoparticles into MOF and encapsulating by excellent conductor rGO thin sheets, a series of mesoporous composites of UiO-67/CdS/rGO-x were developed. As a result, the obtained UiO-67/CdS/rGO-1 showed the highest OFL degradation efficiency of 93.4% within 30 min for a 10 ppm OFL solution under the simulated sunlight, in which the turnover frequency (TOF) of 5.44 × 10−3 g(OFL) min−1 g(Cat.)−1 showed an order of magnitude increase over the relevant works. The mechanism study revealed the superoxide radicals O2− and photo-generated hole h+ were the excitons for the photocatalytic oxidation. The equalized Fermi level of UiO-67/CdS heterojunctions was formed to facilitate the electrons relaying, spilling-over, and penetrating through wrapped thin-layered rGO; meanwhile, the selective adsorption of OFL synergistically enhanced the photocatalysis, and hence provided a promising strategy for environmental remediation.

Monitoring and optimization of diclofenac removal by adsorption technique using in-line potentiometric analyzer

Diclofenac (DICLO) is one of the most prescribed non-steroidal anti-inflammatory drugs worldwide. The presence of DICLO residues in aquatic environment either from industrial or hospital wastewater has harmful effects on many organisms. In this contribution, the adsorption of DICLO on granulated active carbon and mesoporous silica nanoparticles was optimized in order to remove those residues from water. The tracking of DICLO was done using in-line potentiometric ion-selective electrodes (ISE) through the whole experiments. The constructed electrode allows tracking of DICLO residues in real time. A central composite design was applied, inspecting the pH, initial concentration, adsorbent loading concentration and adsorbent type effects on the adsorption process, the results showed that the pH effect was most significant; pH 5 gave best results. The adsorption kinetics of these adsorbents have been investigated and the results indicated that the adsorption process followed the pseudo-second-order kinetic model. The adsorption isotherm data were analyzed by both Langmuir and Freundlich models and later provides better fit of the experimental data. The removal efficiency was about ~89% upon applying the optimum set of experimental conditions in time < 60 min. In-line monitoring is considered a green protocol, that should be carried out also at the pharmaceutical industry scale due to the high selectivity, lack of harmful waste generation and minimal solvent use.

Uptake and translocation of organophosphate flame retardants (OPFRs) by hydroponically grown wheat (Triticum aestivum L.)

The increasing load of organophosphate flame retardants (OPFRs) has generated wide concerns about their potential residues in aquatic environments. The uptake and translocation of fourteen OPFRs by wheat (Triticum aestivum L.) were studied under hydroponic conditions. The results revealed that OPFRs were removed from hydroponic solution by wheat, and the removal processes followed first-order kinetics. After 10 days, the removal efficiencies were in a range of 57.9 ± 3.8%−63.8 ± 5.6%. The potential for translocation of these OPFRs from the roots to foliage was also assessed. OPFRs with relatively higher hydrophobicity were more likely taken up by roots, and OPFRs with lower hydrophobicity were more prone to be translocated. Root concentration factors (RCFs), transpiration stream concentration factors (TSCFs), and foliage/root concentration factors (FRCFs) were calculated. Furthermore, significant correlations were found between RCF, FRCF or TSCF values of OPFRs and log Kow (p < 0.05), and translocation of OPFRs depended on their physicochemical properties. The findings of this study develop better understanding of accumulation and translocation of OPFRs in plants, which is valuable for environmental and human health assessments of such kind of contaminants.

Functionalized magnetic nanomaterials for rapid and effective adsorptive removal of fluoroquinolones: Comprehensive experimental cum computational investigations.

Alarming growth of pharmaceutical residues in aquatic environment has elevated concerns about their potential impact on human health. Taking cognizance of this, the present study is focussed on the coating of cobalt ferrite nanoparticles with different functionalities and to use them as adsorbents for pharmaceutical waste. The thickness of the coating was analysed using Small angle X-ray scattering technique. Thorough study of the isotherms and kinetics were performed suggesting monolayer adsorption and pseudo kinetic order model, respectively. To get an insight of the interactions liable for adsorption of fluoroquinolones over the functionalized magnetic nanoparticles computational studies were undertaken. The results demonstrated substantial evidence proposing remarkable potential of these nanostructures as adsorbents for different pollutants with an additional advantage of stability and facile recoverability with a view to treat wastewater.

Antibacterial potential of phytochemicals alone or in combination with antimicrobials against fish pathogenic bacteria.

This study investigated the antibacterial activity of five phytochemicals (carvacrol, citral, eugenol, linalool and thymol) alone or in combination with florfenicol or oxytetracycline against bacteria isolated from silver catfish (Rhamdia quelen). We also analysed the potential of these compounds to inhibit biofilm formation and haemolysis caused by the bacteria. Bacteria were tested with antimicrobials to calculate the multiple antibiotic resistances. The checkerboard assay was used to evaluate a putative synergy between five phytochemicals and antimicrobials against the strains isolated. The biofilm formation inhibition assay was performed with phytochemicals and antimicrobials, and the haemolysis inhibition assay was performed with the phytochemicals. Carvacrol, eugenol and thymol were the most effective phytochemicals. Three combinations (linalool with florfenicol or oxytetracycline against Aeromonas hydrophila and citral with oxytetracycline against Citrobacter freundii) demonstrated synergy in the checkerboard assay. All phytochemicals inhibited biofilm formation and haemolysis activity. The tested phytochemicals showed satisfactory activity against fish pathogenic bacteria. The phytochemicals did not present antagonistic interactions with the antimicrobials, allowing their combined use, which may contribute to a decrease in the use of conventional drugs and their residues in aquatic environment.

Occurrence and Distribution of Veterinary Residues in Aquatic Environments near Livestock and Poultry Farms in Zhejiang Province, China

Occurrence and Distribution of Veterinary Residues in Aquatic Environments near Livestock and Poultry Farms in Zhejiang Province, China

Pharmaceutical residues in aquatic environment and water remediation by TiO2 heterogeneous photocatalysis: a review

The occurrence of pharmaceutical compounds in the natural water sources has been reported as early as in the year 1980. Until now, the presence of pharmaceutical compounds in the aquatic environment has been frequently reported in the literature. Moreover, increasing evidence suggests that these contaminants have posed a threat to both humans and ecosystems. In this regard, the present review paper seeks to offer an overview of this environmental issue of pharmaceutical pollution where the subject matters to be reviewed include the effects, sources and mitigation strategies of pharmaceuticals in the aquatic environment. Besides, a review of the fundamentals and mechanisms of heterogeneous photocatalysis technology is also presented in this paper. Heterogeneous photocatalysis is a rapidly expanding technology which has been extensively investigated and applied in wastewater treatment for the remediation of persistent pollutants such as pharmaceutical compounds during the last decade. Furthermore, the ideal photocatalyst titanium dioxide (TiO2), which can collaborate and perform well in the photocatalysis treatment process, is also discussed. The advantages and limitations associated with the application of this treatment method are summarized and discussed in details. Finally, this review paper focuses on the future trend of the photocatalysis technology and identifies the barriers and lacking parts which need to be resolved in the near future.

Highly efficient removal of chlorotetracycline from aqueous solution using graphene oxide/TiO2 composite: Properties and mechanism

The extensive usage of chlorotetracycline (CTC) has caused the persistence of antibiotic residues in aquatic environments, resulting in serious threat to human health and ecosystems. In this study, graphene oxide/titanium dioxide (GO/TiO2) nanocomposite was successfully synthesized via in situ hydrolysis of tetra-n-butyl titanate (Ti(BuO)4) to TiO2 particles on GO sheets and used as adsorbent for efficient adsorptive removal of CTC from aqueous solution. The prepared GO/TiO2 was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), Raman spectroscopy and X-ray photoelectron (XPS). Adsorption kinetics, isotherms and thermodynamics were systematically investigated to evaluate the adsorption properties of GO/TiO2. Adsorption mechanism was further analyzed by FT-IR, UV–vis and XPS. The results indicated that adsorption kinetics closely followed the pseudo-second order model; the maximum adsorption capacity determined by Langmuir model was 261.10mgg−1 at 298K and the thermodynamic studies revealed that the adsorption of CTC onto the GO/TiO2 was a spontaneous and endothermic process. Moreover, the interactions between CTC and GO/TiO2 were presumed to be ligand exchange between CTC and TiO2, while the π-π electron donor-acceptor interaction, hydrogen bond and cation-π bonding were constructed between CTC and GO. Finally, the prepared GO/TiO2 was successfully applied for the efficient removal of CTC from Wu River water.

A survey of 17α-ethinylestradiol and mestranol residues in Hawkesbury River, Australia, using a highly specific enzyme-linked immunosorbent assay (ELISA) demonstrates the levels of potential biological significance

This study reports on the potential status of 17α-ethinylestradiol (EE2) and mestranol (MeEE2) residues in aquatic environments in New South Wales (NSW), Australia, based on the analysis by a specific ELISA we developed. Polyclonal antibodies were raised against the EE2 hapten with a linker attached at the C3-position to direct the antibody binding towards the ring D of EE2/MeEE2. Using this approach, an ELISA highly specific to EE2 and MeEE2 was successfully developed, showing less than 3.1% cross-reactivity (% CR) with other major steroidal sex hormones and their derivatives. The assay performed with the limit of detection (LOD) of 0.04 ± 0.01µg/L for both EE2 and MeEE2, and the limit of quantitation (LOQ) of 0.05 ± 0.01ng/L when it was coupled with the SM2-Biobeads solid phase extraction. Prior to conducting the survey study, it was validated against the gas chromatography-mass spectrophotometry (GC-MS) method, which showed high correlation with R2 of 0.934. Fresh surface water samples collected at different sites along Hawkesbury River in New South Wales (NSW) were analyzed for the EE2/ MeEE2 residues using the developed ELISA. The EE2/MeEE2 levels were found to range between 4.1 and 8.3ng/L in Emigrant Creek, NSW, where the primary activity was macadamia plantation, and higher levels between 15 and 29ng/L in South Creek, NSW, Greater Western Sydney at sites upstream and downstream of the municipal sewage treatment plants.

Phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia in a horizontal subsurface flow constructed wetland

Widespread occurrence of trace pharmaceutical residues in aquatic environments is of great concerns due to the potential chronic toxicity of certain pharmaceuticals including ibuprofen on aquatic organisms even at environmental levels. In this study, the phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia were investigated in a horizontal subsurface flow constructed wetland system. The experimental wetland system consisted of a planted bed with Typha angustifolia and an unplanted bed (control) to treat ibuprofen-loaded wastewater (∼107.2 μg L−1). Over a period of 342 days, ibuprofen was accumulated in leaf sheath and lamina tissues at a mean concentration of 160.7 ng g−1, indicating the occurrence of the phytoextraction of ibuprofen. Root-uptake ibuprofen was partially transformed to ibuprofen carboxylic acid, 2-hydroxy ibuprofen and 1-hydroxy ibuprofen which were found to be 1374.9, 235.6 and 301.5 ng g−1 in the sheath, respectively, while they were 1051.1, 693.6 and 178.7 ng g−1 in the lamina. The findings from pyrosequencing analysis of the rhizosphere bacteria suggest that the Dechloromonas sp., the Clostridium sp. (e.g. Clostridium saccharobutylicum), the order Sphingobacteriales, and the Cytophaga sp. in the order Cytophagales were most probably responsible for the rhizodegradation of ibuprofen.

Phytoremediation of imazalil and tebuconazole by four emergent wetland plant species in hydroponic medium

Pollution from pesticide residues in aquatic environments is of increasing concern. Imazalil and tebuconazole, two commonly used systemic pesticides, are water contaminants that can be removed by constructed wetlands. However, the phytoremediation capability of emergent wetland plants for imazalil and tebuconazole, especially the removal mechanisms involved, is poorly understood. This study compared the removal of both pesticides by four commonly used wetland plants, Typha latifolia, Phragmites australis, Iris pseudacorus and Juncus effusus, and aimed to understand the removal mechanisms involved. The plants were individually exposed to an initial concentration of 10 mg/L in hydroponic solution. At the end of the 24-day study period, the tebuconazole removal efficiencies were relatively lower (25%–41%) than those for imazalil (46%–96%) for all plant species studied. The removal of imazalil and tebuconazole fit a first-order kinetics model, with the exception of tebuconazole removal in solutions with I. pseudacorus. Changes in the enantiomeric fraction for imazalil and tebuconazole were detected in plant tissue but not in the hydroponic solutions; thus, the translocation and degradation processes were enantioselective in the plants. At the end of the study period, the accumulation of imazalil and tebuconazole in plant tissue was relatively low and constituted 2.8–14.4% of the total spiked pesticide in each vessel. Therefore, the studied plants were able to not only take up the pesticides but also metabolise them.