Sunlight Induces the Production of Atmospheric Volatile Organic Compounds (VOCs) from Thermokarst Ponds.

Ground subsidence caused by permafrost thawing causes the formation of thermokarst ponds, where organic compounds from eroding permafrost accumulate. We photolyzed water samples from two such ponds in Northern Quebec and discovered the emission of volatile organic compounds (VOCs) using mass spectrometry. One pond near peat-covered permafrost mounds was organic-rich, while the other near sandy mounds was organic-poor. Compounds up to C10 were detected, comprising the atoms of O, N, and S. The main compounds were methanol, acetaldehyde, and acetone. Hourly VOC fluxes under actinic fluxes similar to local solar fluxes might reach up to 1.7 nmol C m-2 s-1. Unexpectedly, the fluxes of VOCs from the organic-poor pond were greater than those from the organic-rich pond. We suggest that different segregations of organics at the air/water interface may partly explain this observation. This study indicates that sunlit thermokarst ponds are a significant source of atmospheric VOCs, which may affect the environment and climate via ozone and aerosol formation. Further work is required for understanding the relationship between the pond's organic composition and VOC emission fluxes.

Model of shrimp pond-mediated spatiotemporal dynamic distribution of antibiotic resistance genes in the mangrove habitat of a subtropical gulf.

Aquacultures are the main reason for the environmental selection of antibiotic resistance genes (ARGs), resulting in the enrichment of ARGs. As a filter, a marine mangrove ecosystem can reduce antimicrobial resistance (AMR) or eliminate ARGs; however, its elimination mechanism remains unclear. This study investigated the spatiotemporal dynamic distribution of ARGs in two different types of mangrove habitats (shrimp ponds and virgin forests), within a subtropical gulf located in the Beibu Gulf, China, during dry and wet seasons by using metagenomics and real time quantitative polymerase chain reaction (RT-qPCR) analysis. As the key environmental factors, sulfide, salinity, and mobile genetic elements significantly were found to contribute to ARGs distribution, respectively. Wet and dry seasons influenced the dispersal of ARGs but did not affect the microbial community structure. Three potential biomarkers, TEM-116, smeD, and smeE, played key roles in seasonal differences. The key different genes in the biological relevance of absolute abundance were demonstrated by RT-qPCR. Co-occurrence network analysis indicated that high-abundance ARGs were distributed in a modular manner. For the first time, a risk index weighted by risk rank (RIR) was proposed and used to quantify the human risk of ARGs in the mangrove metagenome. The shrimp ponds during the wet season showed the highest RIR detected. In addition to offering a perspective on reducing AMR in mangrove wetlands, this study constructed the first spatiotemporal dynamic model of ARGs in the Beibu Gulf, China and contributed to revealing the global spread of ARGs. Meanwhile, this study proposes a new pipeline for assessing the risk of ARGs, while also exploring the concept of "One Health."

A highly sensitive surface-enhanced Raman scattering sensor with MIL-100(Fe)/Au composites for detection of malachite green in fish pond water.

Concerns about food safety have been arisen due to the improper use of chemicals in aquaculture. Malachite green (MG) has attracted attention because of its illegal usage and its potential negative impacts on the environment and public health. Surface-enhanced Raman scattering (SERS) platforms coupled with different SERS substrates have been employed for rapid analysis of MG residues in food. However, the most commonly used SERS substrates were non-reusable and showed limited detection sensitivity. In this study, a novel SERS substrate with a good recyclability and a high sensitivity was prepared by electrostatically assembling together a metal-organic framework material called materials of institute lavoisie-100(Fe) (MIL-100(Fe)) and Au NPs. The lowest detectable concentration of MG was 10-13 M based on the optimal substrate. The SERS sensor was applied for the detection of the trace MG in fish pond water, which was accomplished with the correlation coefficients R2 = 0.991-0.996 in a concentration range of 10-6-10-13 M. Moreover, MIL-100(Fe)/Au was recycled at least five times, realizing a "detection to degradation", showing great potential for food contamination monitoring due to its distinguished performance.

Occurrence, distribution, and ecological risks of antibiotics in Honghu Lake and surrounding aquaculture ponds, China.

Antibiotics are largely applied in aquaculture to increase production and control diseases, while how the antibiotics used in pond farming influence the distribution of antibiotics in receiving water seasonally is still not well understood. In this study, the variations of 15 frequently used antibiotics in Honghu Lake and surrounding ponds were investigated seasonally to figure out the impact of pond farming on antibiotics distributions in Honghu Lake. Results showed that the antibiotic concentrations in fish ponds ranged from 11.76 to 389.8 ng/L, while in crab and crayfish ponds were lower than 30.49 ng/L. The predominant antibiotic in fish ponds was florfenicol, followed by sulfonamides and quinolones, with generally low concentrations. Sulfonamides and florfenicol were the main antibiotics in Honghu Lake, affected by the surrounding aquaculture water partially. The antibiotics residue in aquaculture ponds showed obvious seasonal characteristics, with the lowest in spring. From summer, the concentrations of antibiotics in aquaculture ponds gradually increased and reached a peak in autumn, and the seasonal variation of antibiotics in the receiving lake was also related to the antibiotics in the aquaculture ponds. Risk assessment analysis showed that antibiotics such as enrofloxacin and florfenicol in fish ponds posed a medium and low risk to algae, and Honghu Lake acted as a natural reservoir of antibiotics and poses increased risks to algae. In general, our study demonstrated that aquaculture represented by pond farming brought significant risks of antibiotic pollution to natural water bodies. Therefore, reasonable control of the fish antibiotics usage in autumn and winter, as well as the rational use of antibiotics in aquaculture and the use of antibiotics before pond cleaning, is required to reduce the migration of antibiotics from aquaculture surface water to the receiving lake.

Ecological and health risk assessment and quantitative source apportionment of dissolved metals in ponds used for drinking and irrigation purposes.

In this study, dissolved metal levels of 10 different ponds used as irrigation and drinking water sources in the north of Saros Bay (Türkiye) were evaluated using multivariate statistical methods, contamination and ecological risk indices, and absolute principal component score-multiple linear regression (APCS-MLR). The mean levels of metals in the ponds ranged from 0.045 µg/L (Cd) to 127 µg/L (Mn). Pond 7 used for drinking water source had the lowest total metal level. Only Mn levels in two ponds (P1 and P2) slightly exceeded the critical value set by EU Drinking Water Directive. However, the levels of all metals in all ponds were lower than the critical values set for irrigation water and aquatic life. According to the heavy metal pollution index (HPI), five ponds showed low metal pollution in terms of drinking water quality, four ponds showed moderate metal pollution, and one pond (P1) showed moderate to heavy pollution. According to the Nemerow pollution index (NPI) values (0.26-1.82), ponds P1 and P2 showed slight metal pollution, while other ponds showed insignificant metal pollution. Contamination degree (CD) values of ponds varied between 0.95 and 3.33, indicating that all ponds showed low pollution. In terms of irrigation water quality, all ponds showed low or insignificant metal pollution according to the HPI, NPI, and CD values. According to the ecological risk index (ERI) values, metals in all ponds posed low ecological risks for both drinking and irrigation purposes. Factor analysis identified two potential sources: mixed sources and natural sources. The APCS-MLR model results revealed that mixed sources and natural sources contributed 78.99% and 21.01% to dissolved metals in the ponds, respectively. Health risk assessment results indicated that both individual and combined metals in the ponds would not cause non-carcinogenic risks to both adults and children. Similarly, it was found that Cr and As would not cause carcinogenic risks to the residents of the region.

Enrofloxacin-induced transfer of multiple-antibiotic resistance genes and emergence of novel resistant bacteria in red swamp crayfish guts and pond sediments.

Antibiotic resistance genes (ARGs) can be transferred from environmental microbes to human pathogens, thus leading to bacterial infection treatment failures. The aquaculture polluted by over-used antibiotics is considered as a notorious reservoir of ARGs. However, the origin, diachronic changes, and mobility of ARGs under antibiotic exposure in aquaculture systems remain elusive. Our findings showed that enrofloxacin application also increased the relative abundance of various ARGs in addition to quinolone-resistance genes and induced ARG dissemination in crayfish gut and sediment bacteria. Further investigation indicated that the transposase-mediated recombination was the major driver of horizontal gene transfer (HGT) of ARGs under antibiotic stress. Notably, enrofloxacin application also induced the generation of some metagenome-assembled genomes (MAGs) carrying multiple ARGs, which were identified as novel species. Additionally, Enterobacteriaceae constituted a mobile ARG pool in aquaculture. Therefore, aquaculture provides potential wide environmental pathways for generation and spread of antibiotic resistance. Our findings of ARG temporal variations and dissemination pattern in aquaculture with artificial use of antibiotics are critical to the management of antibiotic resistance, which is of great ecosystem and health implications.

Characterization of Dissolved Organic Matter in Solar Ponds by Elemental Analysis, Infrared Spectroscopy, Nuclear Magnetic Resonance and Pyrolysis-GC-MS.

The abundance and chemical composition of dissolved organic matter (DOM) in the brine of solar ponds affect the efficiency of mineral extraction and evaporation rates of the brine, and cause undesired odor and color of the products. Here, we report an investigation into the composition and changes of DOM in solar ponds from Salt Lake brine with multiple complementary analysis techniques. The results showed that the DOM derived from Salt Lake brine was primarily composed of carbohydrates, aliphatic and aromatic compounds. The concentrations of dissolved organic carbon in solar ponds increased with exposure time by up to 15-fold (from 23.4 to 330.8 mg/L) upon evaporation/irradiation of Salt Lake brine. Further qualitative analyses suggest that the relative abundance of aliphatic compounds (including functionalized ones) increased from 49.5% to 59.2% in the solar pond process, while the opposite was observed for carboxylic acid moieties, aromatics and carbohydrates, which decreased from 15.7%, 7.1% and 26.1% to 13.4%, 5.3% and 23.0%, respectively. The pyrolysis-gas chromatography-mass spectrometry results reveal that the presence of some sulfur-containing organics implied some anaerobic biotic decay, but microbiological processes were probably subordinate to photo-induced DOM transformations. In the Salt Lake brine, exposure-driven decay decreased the abundance of polysaccharides and increased that of mono- and polyaromatic pyrolysis products. Our results here provide new insights for better understanding the changes of DOM chemical composition in the solar ponds of Salt Lake brine.

Treatment of waste stabilization pond effluent using natural zeolite for irrigation potential.

Direct utilization of treated effluent from natural treatment systems for irrigation can be challenging on sensitive plants due to high levels of salinity. Post-treatment of such an effluent prior to its applicability in irrigation can be of significant importance. In this study, the wastewater from a natural treatment plant was treated using a lab-scale filtration system with zeolite as a filter material. Three different column depths (0.5 m, 0.75 m, and 1 m) were used to investigate the effect of column depth on the treatment efficiency of the media. The suitability of the raw wastewater and the treated effluent from each column for irrigation purposes was investigated. The water quality parameters investigated were; electrical conductivity (EC), total dissolved solids (TDS), sodium (Na+), calcium (Ca2+), and magnesium (Mg2+). From the analysis results, it was observed that the column depth had a significant influence on the removal efficiency of the pollutants. The highest removal efficiency (94.58%) was achieved from the combination of electrical conductivity and 1 m column depth, while the lowest removal efficiency (10.05%) was observed from the combination of calcium and 0.5 m column depth. The raw wastewater fell mostly into a "very high" hazard, which is class four (C4) based on electrical conductivity and class four (S4) based sodium adsorption ratio; making it unsuitable for irrigation purposes. However, when the wastewater was subjected to 1 m column depth, the quality of the treated effluent improved significantly which in turn also improved the suitability of the effluent for irrigation purposes, with percent compliance ranging from 20.19% to 97.54%.

Evaluation of occurrence, fate and removal of priority phthalate esters (PAEs) in wastewater and sewage sludge by advanced biological treatment, waste stabilization pond and constructed wetland.

Phthalate Esters (PAEs), detected in high concentrations generally in treated wastewater discharged from wastewater treatment plants (WWTPs), are important pollutants that restrict the reuse of wastewater. Investigating the fate of these endocrine-disrupting chemicals in WWTPs is crucial in order to protect both receiving environments and ecosystems. For this purpose, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP) and benzyl butyl phthalate (BBP) in the group of PAEs were monitored in simultaneously both in wastewater and sludge lines of selected two nature-based WWTPs and one advanced biological WWTP. Although it was frequently stated that phthalates were significantly removed in WWTPs in many studies found in literature, negative removal efficiencies of selected phthalates in investigated WWTPs during the sampling period were observed generally in this study. One of the reasons for this concentration increase could be releasing of phthalates from microplastics in wastewater during the treatment process or the desorption of PAEs from treatment sludge. DNOP was the compound with the highest concentration increase at almost each treatment unit of the three WWTPs. On the other hand, total PAEs load was 1997 g d-1 in advanced biological WWTP and adsorption onto sludge of PAEs were determined as 90%. The side-stream total load returned from the decanter supernatant was 0.02% of the total PAEs load coming to advanced biological WWTP from the sewer system. As a result of detailed statistical analysis, the correlation between raw wastewater and primary clarifier (PC) effluent was determined as an increasing linear relation for DEHP and DNOP. On the other hand, moderate and strong correlations were observed both between septic tank and constructed wetland (CW) processes with raw wastewater. In the waste stabilization pond (WSP), while a significant correlation was not found between the sludge line data, homogeneous variance, strong and moderate correlations were obtained in the wastewater line data. However, while mean differences for all investigated PAEs were not significant (p > 0.05) in the wastewater line, mean differences of DEHP (p < 0.05) were significant in the sludge line according to ANOVA analysis.

Reliability of environmental DNA surveys to detect pond occupancy by newts at a national scale.

The distribution assessment and monitoring of species is key to reliable environmental impact assessments and conservation interventions. Considerable effort is directed towards survey and monitoring of great crested newts (Triturus cristatus) in England. Surveys are increasingly undertaken using indirect methodologies, such as environmental DNA (eDNA). We used a large data set to estimate national pond occupancy rate, as well as false negative and false positive error rates, for commercial eDNA protocols. Additionally, we explored a range of habitat, landscape and climatic variables as predictors of pond occupancy. In England, 20% of ponds were estimated to be occupied by great crested newts. Pond sample collection error rates were estimated as 5.2% false negative and 1.5% false positive. Laboratory error indicated a negligible false negative rate when 12 qPCR replicates were used. Laboratory false positive error was estimated at 2% per qPCR replicate and is therefore exaggerated by high levels of laboratory replication. Including simple habitat suitability variables into the model revealed the importance of fish, plants and shading as predictors of newt presence. However, variables traditionally considered as important for newt presence may need more precise and consistent measurement if they are to be employed as reliable predictors in modelling exercises.

Assessment of the effectiveness of a field-scale combined ecological treatment system at removing water pollutants, after optimization using a system dynamic model: a case study of rural inland ponds in China.

Field-scale combined ecological treatment systems (FCETS) are designed to remove nutrients from aquaculture wastewater in ponds according to the characteristics of the nutrients present. We designed and established a numerical model based on the system dynamic (SD) method, to optimize the parameters of FCETS. Results showed that the mean removal rates of TSS, TN, NO3--N, NH4+-N, TP, DP, and CODMn ranged from 83.3 to 125.8%, 41.1 to 49.1%, 44.8 to 56.2%, 49.3 to 55.6%, 80.0 to 88.2%, 52.6 to 65.0%, and 52.0 to 61.5%, respectively. The SD model provided satisfactory estimates of water quality at the outlet throughout both the validation and calibration periods. In addition, we conducted a sensitivity analysis to determine the key parameters of the SD model. This also involved optimization of the N and P removal capacity of FCETS, and their corresponding discharge (Q), and concentration (C) at the inlet. This made it possible to use R and MATLAB to simulate seasonal differences in the removal of N and P. Our results indicate that a FCETS can be used to efficiently remove nutrients from rural wastewater in ponds. In addition, we demonstrated that the SD-based numerical model is a useful management support tool to ensure that decisions are made which result in the stable operation of a FCETS. This illustrates that contamination-free aquaculture from rural inland ponds is a feasible goal.

Ecological response to antibiotics re-entering the aquaculture environment with possible long-term antibiotics selection based on enzyme activity in sediment.

Antibiotics are frequently applied in aquaculture to control infectious diseases and promote aquaculture production. The long-term application of antibiotics can lead to antibiotic resistance within an ecosystem. Herein, we assessed the ecological responses to two antibiotics (oxytetracycline (OTC) and sulfadiazine (SD)) at three concentrations (0 mg/kg (control), 10 mg/kg, and 1000 mg/kg) re-entering the aquaculture sediments of shrimp ponds with an approximately long-term drug application history (5, 15, and more than 30 years) for 2 and 4 months. For the newly reclaimed aquaculture ponds (approximately 5 years), the re-entered OTC significantly promoted urease activity (UA) and peroxidase activity (POA), while inhibited dehydrogenase activity (DHA) and fluorescein diacetate esterase activity (FDA). Meanwhile, the re-entered SD showed promotional effects on POA and DHA, and inhibitory effects on UA and FDA. For ponds with 15 years of aquaculture history, re-entered OTC promoted POA, inhibited FDA, and changed the influencing effects of UA and DHA with exposure time. The re-entered SD showed promotional effects on UA, POA and DHA, and inhibitory effects on FDA. For long-term aquaculture ponds (more than 30 years of aquaculture history), re-entered OTC promoted POA, DHA, and FDA, while it inhibited UA. Meanwhile, SD promoted all four enzyme activities. Pearson correlation analysis indicated that the variances of enzyme responses to the re-entry of antibiotics in the three sediment environments were related with the type, concentration, and exposure time of antibiotics, as well as the sediment properties and aquaculture history. The enzyme activities in the sediment environment from newly reclaimed aquaculture ponds were more sensitive to the re-entered antibiotics, while the enzyme activities displayed a clear tolerance in the sediment environment with more than 30 years of aquaculture history. However, in the sediment environment with 15 years of aquaculture history, the response of the enzyme activities to re-entered antibiotics demonstrated time processes of antibiotic adaptation during antibiotic resistance selection. This study has illustrated the effects of re-entered antibiotics on enzyme activities in the aquaculture environment with long-term antibiotic resistance/tolerance profiles, and further establishes the possible effects on ecosystem functioning in continuous antibiotic selection pressure.

Effect of enzymatic pre-treatment on thermophilic composting of shrimp pond sludge to improve ammonia recovery.

In recent years, attempts have been made to develop a thermophilic composting process for organic sludge to produce ammonia gas for high value-added algal production. However, the hydrolysis of non-dissolved organic nitrogen in sludge is a bottleneck for ammonia conversion. The aim of this study was to identify enzymes that enhance sludge hydrolysis in a thermophilic composting system for ammonia recovery from shrimp pond sludge. This was achieved by screening useful enzymes to degrade non-dissolved nitrogen and subsequently investigating their effectiveness in lab-scale composting systems. Among the four hydrolytic enzyme classes assessed (lysozyme, protease, phospholipase, and collagenase), proteases from Streptomyces griseus were the most effective at hydrolysing non-dissolved nitrogen in the sludge. After composting sludge pre-treated with proteases, the final amount of non-dissolved nitrogen was 46.2% of the total N in the control sample and 22.3% of the total N in the protease sample, thus increasing the ammonia (gaseous and in-compost) conversion efficiency from 41.5% to 56.4% of the total N. The decrease in non-dissolved nitrogen was greater in the protease sample than in the control sample during the pre-treatment period, and no difference was observed during the subsequent composting period. These results suggest that Streptomyces proteases hydrolyse the organic nitrogen fraction, which cannot be degraded by the bacterial community in the compost. Functional potential analysis of the bacterial community using PICRUSt2 suggested that 4 (EC:3.4.21.80, EC:3.4.21.81, EC:3.4.21.82, and EC:3.4.24.77) out of 13 endopeptidase genes in S. griseus were largely absent in the compost bacterial community and that they play a key role in the hydrolysis of non-dissolved nitrogen. This is the first study to identify the enzymes that enhance the hydrolysis of shrimp pond sludge and to show that the thermophilic bacterial community involved in composting has a low ability to secrete these enzymes.

Automated Solid-Phase Microextraction and Negative Chemical Ionization GC-MS for the Measurement of Synthetic Pyrethroids.

Synthetic pyrethroids are frequently detected as trace contaminants in sediment and natural waters. Because of the importance of measuring both total and freely available concentrations for ecotoxicity evaluations, solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry using negative chemical ionization (NCI-GC-MS) was investigated as an analytical technique. Automated SPME-NCI-GC-MS quantification of freely dissolved (and thus potentially bioavailable) pyrethroids in aqueous samples containing dissolved organic matter (DOM) was successfully applied. The introduction of stable isotope-labeled pyrethroid calibration standards into the water sample allows for the simultaneous determination of total concentrations. Because pyrethroids adsorb rapidly to container walls (especially in calibration standard solutions without DOM) it was necessary to develop a technique to minimize the resulting time-dependent losses from calibration standard solutions in autosampler vials as they await analysis. A staggered preparation of these analytical calibration standards immediately prior to analysis was shown to ameliorate this problem. The developed method provides accurate and reproducible results for aqueous samples containing a range of dissolved organic matter concentrations (e.g., sediment pore water or sediment/water mixtures) and yields practical benefits in comparison to conventional analysis methods, such as reduced sample volume requirements, reduced solvent consumption, and fewer sample manipulations, and makes simultaneous measurements of freely dissolved/bioavailable pyrethroids and total pyrethroids possible.

Highly sensitive colorimetric determination of nitrite based on the selective etching of concave gold nanocubes.

Concave gold nanocubes are viable optical nanoprobes for the determination of nitrite ions. Herein, a novel approach was developed, based on the measurement of localized surface plasmon resonance absorption. The addition of nitrite ions selectively induced the etching of concave gold nanocubes, abrading the sharp vertices to spherical corners, which resulted in blue-shifted absorption accompanied by a color change from sapphire blue to light violet. The mechanism of selective etching of concave gold nanocube tips was elucidated by using X-ray photoelectron spectroscopy and atom probe tomography. The optimized detection of NO2- via the concave gold nanocube-based probe occurred at pH 3.0 and in 20 mM NaCl concentration at 40 °C. The absorption ratios (A550 nm/A640 nm) were proportional to the NO2- concentrations in the range 0.0-30 µM, with a detection limit of 38 nM (limit of quantitation of 0.12 µM and precision of 2.7%) in tap water. The highly selective and sensitive colorimetric assay has been successfully applied to monitor the nitrite ion concentrations in spiked tap water, pond water, commercial ham, and sausage samples.

Flexible and reusable carbon dot decorated natural microcline membrane: a futuristic probe for multiple heavy metal induced carcinogen detection.

A flexible nano-engineered natural mineral (carbon dot doped natural microcline) based membrane (MCPV) has been developed, which can efficiently detect the presence of hexavalent chromium (Cr6+) and trivalent iron (Fe3+) ions in water by altering its fluorescence emission. Detailed characterization of the membrane was carried out using XRD, FT-IR spectroscopy, FESEM, TEM, and UV-Vis spectroscopy. Mechanical and temperature stabilities were also investigated. This new-generation sensor membrane is designed in such a way that it does not dissolve in water, keeping the water quality unaffected. The fluorescence studies were conducted at 414 nm and "turn-off" response was observed specifically for Fe3+ at 489 nm. A prominent red shift (530 nm) of the fluorescence maxima takes place when it comes to Cr6+. Figures of merit, such as LOD (8.7 µM for Cr6+ and 18.4 µM for Fe3+) and LOQ (29.1 µM for Cr6+ and 61.6 µM for Fe3+), were evaluated from the linear range (0-60 µM for Cr6+ and 0-30 µM for Fe3+) of the calibration curve (Stern-Volmer plots) showing high sensitivity of this sensing probe toward Cr6+ and Fe3+. Recovery and RSD calculations were done in various real-life water samples on intraday-interday basis to determine the accuracy of the sensor. This work validates the fact that the synthesized sensor membrane is capable of detecting these heavy metals in glutathione environment as well, which could be beneficial for early-stage carcinogen detection in living cells.

Greenhouse gases emissions from duckweed pond system treating polyester resin wastewater containing 1,4-dioxane and heavy metals.

Phytoremediation of polyester resin wastewater containing 1,4-dioxane and heavy metals using Lemna gibba (L.gibba) was enhanced by incorporation of perforated polyethylene carrier materials (PCM) onto the duckweed pond (DWP) system. The DWP module was operated at a hydraulic retention times (HRTs) of 2, 4 and 6 days and as well as 1,4-dioxane loading rate of 16, 25 and 48 g/m3.d. The maximum removal efficiency of 54 ± 2.5% was achieved for 1,4-dioxane at an HRT of 6 days and loading rate of 16 g1,4-dioxane/m3.d. Similarly, the DWP system provided removal efficiencies of 28.3 ± 2.1, 93.2 ± 7.6, 95.7 ± 8.9 and 93.6 ± 4.9% for Cd2+, Cu2+, Zn2+ and Ni2+ at influent concentration of 0.037 ± 0.01, 1.2 ± 0.9, 27.2 ± 4.7 and 4.6 ± 1.2 mg/L respectively. The structural analysis by Fourier-transform infrared spectroscopy (FTIR) clearly displayed a reduction of 1,4- dioxane in the treated effluent. A strong peak was detected for L. gibba plants at frequency of 3417.71 cm-1 due to N-H stretching, which confirm the proposed mechanism of partially conversion of 1,4-dioxane into amino acids. Glycine, serine, aspartic, threonine and alanine content were increased in L. gibba by values of 35 ± 2.2, 40 ± 3.2, 48 ± 3.7, 31 ± 2.8, and 56 ± 4.1%, respectively. The contribution of DWP unit as a greenhouse gases (GHG) emissions were relatively low (1.65 gCO2/Kg BODremoved.d., and 18.3 gCO2/Kg biomass.d) due to photosynthesis process, low excess sludge production and consumption of CO2 for nitrification process (1.4 gCO2/kgN removed.d). Based on these results, it is recommended to apply such a technology for treatment of polyester resin wastewater containing 1,4-dioxane and heavy metals at a HRT not exceeding 6 days.

Spread of resistance genes from duck manure to fish intestine in simulated fish-duck pond and the promotion of cefotaxime and As.

Integrated culture is a widespread culture mode in South China, in which resistance genes (RGs) also spread in the circulation system with nutrients. Accordingly, the aim of the present study was to investigate the spread of RGs in a fish-duck pond and the RGs and bacterial community of fish intestines. Five fish tanks, including a control tank and four experimental tanks (duck manure, duck manure + cefotaxime, duck manure + As, and duck manure + cefotaxime + As), were tested for 100 days. The results showed that duck manure increased both the diversity and relative abundance of RGs in fish intestines, and the addition of stress factors (cefotaxime, As) increased the relative abundance of RGs by one to two orders of magnitude. The stress-inducing effect of cefotaxime was greater than that of As. Tetracycline resistance genes were more sensitive to stress factors and were the predominant RGs in fish intestines. RGs in duck manure preferentially spread from the water to biofilm and then to fish intestines, whereas co-stress of cefotaxime and As obviously promoted the spread of RGs to fish intestines. In comparison to the control tank, duck manure and stress factors significantly changed the bacterial community of fish intestines. Correlation analysis also revealed that arsB, MOX, tetA and sul1 were significantly correlated with intI1 (P < 0.01), which hinted a potentially dissemination risk of RGs in fish intestines. These findings provide a theoretical basis for further investigating the dissemination of RGs in integrated culture systems and for evaluating the ecological risk of antibiotic and As use in aquaculture.

Fabric phase sorptive extraction followed by HPLC-PDA detection for the monitoring of pirimicarb and fenitrothion pesticide residues.

A sensitive and readily deployable analytical method has been reported for the simultaneous analysis of pirimicarb (PRM) and fenitrothion (FEN) pesticide residues in environmental water samples using fabric phase sorptive extraction (FPSE) followed by high-performance liquid chromatography combined with photodiode array (HPLC-PDA) detector. Both pesticides were successfully determined with a Luna omega C18 column under isocratic elution mode by means of acetonitrile and phosphate buffer (pH 3.0) as the mobile phase. The quantitative data for PRM and FEN were obtained at their maximum wavelengths of 310 nm and 268 nm, respectively. The calibration plots were linear in the range 10.00-750.00 ng mL-1 and 10.00-900.00 ng mL-1 with correlation coefficient of 0.9984 and 0.9992 for PRM and FEN, respectively. Major FPSE experimental variables were investigated in detail, such as contact time with the FPSE membrane, pH and electrolyte concentration, and the volume and type of desorption solvent. Under the optimized conditions, the developed method showed satisfactory reproducibility with relative standard deviations less than 2.5% and low limits of detection of 2.98 and 3.02 ng mL-1 for PRM and FEN, respectively. The combined procedure allows for enhancement factors ranging from 88 to 113, with pre-concentration values of 125 for both analytes. The chromatographic resolutions were approx. 12 for FEN (retention factor of 3.52) and PRM (retention factor of 6.09), respectively, with a selectivity factor of 1.73. Finally, the validated method was successfully applied to real environmental water samples for the determination of these pesticides. Graphical abstract.

Mesoporous Pd@Pt nanoparticle-linked immunosorbent assay for detection of atrazine.

Atrazine is a widely used herbicide in the United States; however, the Environmental Protection Agency (EPA) has issued warnings about atrazine because of its reported potential harmful effects on animals and humans. Therefore, developing efficient ways to detect this herbicide's residue are critically important. The competitive ELISA is a useful method for detecting chemicals for which antibodies exist due to its high sensitivity, specificity, and efficiency. However, the assay typically requires a separate application of a secondary antibody linked to an enzyme that catalyzes conversion of a non-colored organic to a detectable colored product. In this study, we used the recently developed peroxidase-like mesoporous core-shell palladium@platinum (Pd@Pt) nanoparticle which can easily be bound directly to primary antibody, thereby eliminating the need for a secondary antibody conjugate. We report a first instance in which this technique is applied for use in a competitive assay for small molecules, in this case the herbicide atrazine. Due to their high-surface area and mesoporous structure, Pd@Pt nanoparticles enable fast mass transfer for reaction with excellent catalytic activity. This leads to high sensitivity in our immunoassay with a limit of detection of 0.5 ng mL-1 defined by selecting an IC10 concentration, i.e., the analyte concentration at which 10% of the available Pd@Pt nanoparticle-labeled antibody is inhibited from binding to a plate coated with a bovine serum albumin-atrazine conjugate. We applied our method to well-water and pond water samples spiked with atrazine. Our tests at 5, 10, and 20 ng mL-1 yielded recoveries of 99 - 115%, offering strong supporting evidence that atrazine and other low molecular weight herbicides and pesticides can be detected using this immunoassay approach. Detection with this method is expected to lead to its use in a wide spectrum of applications in agriculture, medical, and biotechnology arenas.