Oxygen vacancy-rich Fe2(MoO4)3 combined with MWCNTs for electrochemical sensors of fentanyl and its analogs.

Hundreds of thousands of people dying from the abuse of fentanyl and its analogs. Hence, the development of an efficient and highly accurate detection method is extremely relevant and challenging. Therefore, we proposed the introduction of oxygen defects into Fe2(MoO4)3 nanoparticles for improving the catalyst performance and combining it with multi-walled carbon nanotubes (MWCNTs) for electrochemical detection of fentanyl and its analogs. Oxygen vacancy-rich Fe2(MoO4)3 (called r-Fe2(MoO4)3) nanoparticles were successfully synthesized and characterized in detail by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectra, BET, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) and investigated by comparison with oxygen vacancy-poor Fe2(MoO4)3 (called p-Fe2(MoO4)3). The obtained oxygen vacancy-rich Fe2(MoO4)3 was ultrasonically composited with MWCNTs for modification of glassy carbon electrodes (GCEs) used for the electrochemical detection of fentanyl and its analogs. The modified MWCNT-GCE showed ultrasensitivity to fentanyl, sufentanil, alfentanil, and acetylfentanyl with limits of detection (LOD) of 0.006 µmol·L-1, 0.008 µmol·L-1, 0.018 µmol·L-1, and 0.024 µmol·L-1, respectively, and could distinguish among the four drugs based on their peak voltages. Besides, the obtained r-Fe2(MoO4)3/MWCNT composite also exhibited high repeatability, selectivity, and stability. It showed satisfactory detection performance on real samples, with recoveries of 70.53 ~ 94.85% and 50.98 ~ 82.54% in serum and urine for the four drugs in a concentration range 0.2 ~ 1 µM, respectively. The experimental results confirm that the introduction of oxygen vacancies effectively improves the sensitivity of fentanyl electrochemical detection, and this work provides some inspiration for the development of catalytic materials for electrochemical sensors with higher sensitivity.

PVA/WO3-x/Ag2WO4 Hydrogel for Enhanced Photocatalytic Disinfection and Accelerated Wound Healing.

Bacterial wound infections are one of the growing health and safety threats to the public. In this study, WO3-x/Ag2WO4 photocatalysts were synthesized, and heterogeneous structures were constructed for non-antibiotic bactericidal use. Due to the heterostructure constructed with Ag2WO4, the photogenerated carrier separation efficiency and reactive oxygen generation capacity of WO3-x were improved, which in turn improved the inactivation rate of bacteria. Also, this photocatalyst was loaded into PVA hydrogel for photodynamic treatment of bacterial wound infections. This hydrogel dressing was demonstrated to have good biosafety by in vitro cytotoxicity tests and to have a wound healing-promoting effect by in vivo wound healing experiments. This light-driven antimicrobial hydrogel has the potential ability to treat bacterial wound infections.

Benzoyl isothiocyanate modified surface of silica gel as the extraction material for adsorbing steroid hormones in water.

Steroid hormones have been listed as priority pollutants in the environment, and their detection and pollution control deserve our extensive attention. In this study, a modified silica gel adsorbent material was synthesized by benzoyl isothiocyanate reaction with hydroxyl groups on the silica gel surface. The modified silica gel was used as a solid phase extraction filler for the extraction of steroid hormones from water, which was further analyzed by the HPLC-MS/MS method. The FT-IR, TGA, XPS, and SEM analysis indicated that benzoyl isothiocyanate was successfully grafted on the surface of silica gel to form a bond with an isothioamide group and benzene ring as the tail chain. The modified silica gel synthesized at 40 °C showed excellent adsorption and recovery rates for three steroid hormones in water. Methanol at pH 9.0 was selected as the optimal eluent. The adsorption capacity of the modified silica gel for epiandrosterone, progesterone, and megestrol acetate was 6822 ng mg-1, 13 899 ng mg-1, and 14 301 ng mg-1, respectively. Under optimal conditions, the limit of detection (LOD) and limit of quantification (LOQ) for 3 steroid hormones by modified silica gel extraction with HPLC-MS/MS detection were 0.02-0.88 µg L-1 and 0.06-2.22 µg L-1, respectively. The recovery rate of epiandrosterone, progesterone, and megestrol was between 53.7% and 82.9%, respectively. The modified silica gel has been successfully used to analyze steroid hormones in wastewater and surface water.

Polyimidazolyl acetate ionic liquid grafted on cellulose filter paper as thin-film extraction phase for extraction of non-steroidal anti-inflammatory drugs from water.

Recently, pharmaceuticals and personal care products in the water environment exhibited potential risks to both human and aquatic organisms. In order to improve the sensitivity and accuracy of pharmaceutical detection, the polyimidazolyl acetate ionic liquid was synthesized by Radziszewski reaction and coated on cellulose filter papers as a thin-film extraction phase for extraction of non-steroidal anti-inflammatory drugs from water. The attenuated total reflection-infrared spectrometry, thermogravimetric analysis, and scanning electron microscope analyses demonstrated that the polyimidazolyl acetate ionic liquid was successfully prepared and attached to the surface of the cellulose filter paper through chemical bonding. The adsorption capacity of the homemade thin-film extraction material for the four non-steroidal anti-inflammatory drugs was greater than 8898 ng/cm2 under the optimum conditions, and the desorption rate was over 90%. Then, a paper-based thin-film extraction phase-high-performance liquid chromatography-tandem mass spectrometry method was established for the extraction of non-steroidal anti-inflammatory drugs in water. This method provided limits of detection and limits of quantification were in the range of 0.02-0.15 and 0.17-0.50 µg/L, respectively. Hence, the obtained thin-film extraction phase showed excellent recovery and reproducibility for the target non-steroidal anti-inflammatory drugs with carboxyl groups from water.

One-Step Preparation of Chitosan-Based Magnetic Adsorbent and Its Application to the Adsorption of Inorganic Arsenic in Water.

Chitosan is a kind of biodegradable natural polysaccharide, and it is a very promising adsorber material for removing metal ions from aqueous solutions. In this study, chitosan-based magnetic adsorbent CMC@Fe3O4 was synthesized by a one-step method using carboxymethyl chitosan (CMC) and ferric salts under relatively mild conditions. The Fe3O4 microspheres were formed and the core-shell structure of CMC@Fe3O4 was synthesized in the meantime, which was well characterized via SEM/TEM, XRD, VSM, FT-IR, thermo gravimetric analysis (TGA), XPS, size distribution, and zeta potential. The effects of initial arsenic concentration, pH, temperature, contact time, and ionic strength on adsorption quantity of inorganic arsenic was studied through batch adsorption experiments. The magnetic adsorbent CMC@Fe3O4 displayed satisfactory adsorption performance for arsenic in water samples, up to 20.1 mg/g. The optimal conditions of the adsorption process were pH 3.0, 30-50 °C, and a reaction time of 15 min. The adsorption process can be well described by pseudo-second-order kinetic model, suggesting that chemisorption was main rate-controlling step. The Langmuir adsorption model provided much higher correlation coefficient than that of Freundlich adsorption model, indicating that the adsorption behavior is monolayer adsorption on the surface of the magnetic adsorbents. The above results have demonstrated that chitosan-based magnetic adsorbent CMC@Fe3O4 is suitable for the removal of inorganic arsenic in water.

Extraction of quinolones from milk samples using bentonite/magnetite nanoparticles before determination by high-performance liquid chromatography with fluorimetric detection.

In this work, bentonite magnetic nanoparticles synthesized by a typical coprecipitation method were used as the adsorbent for the magnetic solid-phase extraction of six quinolones (ciprofloxacin, difloxacin, enrofloxacin, norfloxacin, sarafloxacin, and lomefloxacin) from milk samples followed by high-performance liquid chromatography with fluorimetric detection. Under the optimized conditions, the linear quantitation range for the six quinolones was 0.3-200 ng/mL, and the correlation coefficients of the calibration curves ranged from 0.9994 to 0.9999. The detection limit of the method was 0.1 ng/mL. Recoveries of quinolones from pure and low-fat spiked milk samples varied from 80.4 to 92.7% and from 81.3 to 93.5%, respectively. These results demonstrated that the proposed method for the determination of six quinolones in milk samples was rapid, reliable, and efficient.

Analysis of 21 progestagens in various matrices by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with diverse sample pretreatment.

In this study, a highly sensitive and robust method using an ultra-high-performance liquid chromatography-tandem mass spectrometry combined with solid-phase extraction and ultrasonic extraction for pretreatment and silica gel purification steps has been developed for determination of 21 natural and synthetic progestagens in river surface water and sediments, and influents, effluents, and sludge from municipal wastewater treatment plants, and flush water and feces from swine farms. For the various matrices considered, the optimized method showed satisfactory performance with recoveries of 70-129 % (except AD, 5α-DHP, DPT, HPC), the limits of quantification below 2.30 ng/L for liquid samples and 2.59 ng/g for solid samples (except AD), and good linearity and reproducibility. This developed method was successfully applied in the analysis of progestagens in environmental samples from Liuxi Reservoir, Xintang municipal wastewater treatment plant, and Shunfeng swine farm in South China. Six analytes were detected at trace levels in surface water, effluent, and sediment samples. Seven analytes (0.7 (HPA)-35.1 ng/L (DGT)) were found in the influent samples and three analytes (5.6 (DGT)-11.8 ng/g (5α-DHP)) in the dewatered sludge samples. Moreover, 13 analytes were detected in swine farm, with high concentrations ranging from 23.8 ng/L (ET) to 5,024 ng/L (P) in flush water, and from 20.0 ng/g (MPA) to 1952 ng/g (P) in feces.

Bioaccumulation and risk assessment of per- and polyfluoroalkyl substances in wild freshwater fish from rivers in the Pearl River Delta region, South China.

Per- and polyfluoroalkyl substances (PFASs) are used in various industries, which results in their ubiquitous occurrence in the environment. This study determined the concentrations of eighteen PFASs in muscle and liver of nine wild freshwater fish species collected from rivers in the Pearl River Delta (PRD) region, South China, and assessed their bioaccumulation and potential health risks to local people. The results showed that eight and twelve PFASs were detected in the fish muscle and liver samples, respectively. Perfluorooctane sulfonate (PFOS) was found to be the predominant PFAS both in muscle and liver with its highest concentrations of 79ng/g wet weight (ww) in muscle and 1500ng/g ww in liver, followed by Perfluoroundecanoic acid (PFUnDA) and Perfluorotridecanoic acid (PFTrDA) with trace concentrations. The mean PFOS concentrations in fish muscle and liver tissues of the nine collected species ranged from 0.40ng/g in mud carp to 25ng/g in snakehead, and from 5.6ng/g in mud carp to 1100ng/g in snakehead, respectively. Significant positive correlations were found among PFASs both in water and fish, indicating a similar pollution source for these PFASs. In tilapia samples, PFOS concentrations showed an increasing trend with increasing length and weight, but no significant difference between genders. Bioaccumulation factors (logBAF) in fish for the PFASs were in the range from 2.1 to 5.0. The calculated hazard ratios (HR) of PFOS for all fishes were in the range of 0.05-2.8, with four out of nine species (tilapia, chub, leather catfish and snakehead) having their HR values more than 1.0. The results suggest that frequent consumption of these four fish species may pose health risks to local population.

Field dissipation of four personal care products in biosolids-amended soils in North China.

The present study investigated the dissipation behaviors of 4 typical personal care products (PCPs)-triclocarban (TCC), triclosan (TCS), tonalide (AHTN), and galaxolide (HHCB)- in soils amended with biosolids under field conditions in North China. The results showed that the 4 target compounds were detected in all biosolids-amended soils at levels of a few nanograms per gram to thousands of nanograms per gram (dry wt). The residual concentrations of the 4 PCPs were found in the following order: TCC > TCS > AHTN > HHCB. Significant dissipation of the 4 PCPs was observed in the biosolids-amended soils, with half-lives ranging from 26 d to 133 d. Furthermore, repeated biosolids applications and a higher biosolids application rate could lead to higher accumulation of the 4 PCPs in the agricultural soils. Based on the detected concentrations in the field trial and limited ecotoxicity data, high risks to soil organisms are expected for TCC, whereas low to medium risks are expected in most cases for AHTN, HHCB, and TCS.

Triclosan as a surrogate for household biocides: an investigation into biocides in aquatic environments of a highly urbanized region.

Biocides are widely formulated in household and personal care products. We investigated the distribution and ecological risks of 16 household biocides in aquatic environments of a highly urbanized region in South China, evaluated triclosan as a chemical indicator for this group of household chemicals, and proposed a novel approach to predict the environmental occurrence and fate of these household biocides by using triclosan usage data and a level-III fugacity model. Eleven biocides were quantitatively detected at concentrations up to 264 ± 15.3 ng/L for climbazole in surface water, and up to 5649 ± 748 ng/g for triclocarban in sediment of four rivers in the region. The distribution of biocides in the aquatic environments was significantly correlated with environmental variables such as total nitrogen, total phosphorus and population. Domestic sewage in the region was the dominant pollution source for most biocides such as azole fungicides (fluconazole, climbazole, clotrimazole, ketoconazole, miconazole, and carbendazim) and disinfectants (triclosan and triclocarban). Preliminary risk assessment showed high ecological risks posed by two biocides carbendazim and triclosan in river waters. Mostly important, triclosan was found to be a reliable chemical indicator to surrogate household biocides both in water and sediment based on the correlation analysis. In addition, the fugacity modeling could provide simulated concentrations comparable to the monitoring results. Therefore, with the usage data of the chemical indicator triclosan and correlation formula with other biocides, this model can be applied for predicting the occurrence and fate of various household biocides in a catchment.

Occurrence and dissipation of benzotriazoles and benzotriazole ultraviolet stabilizers in biosolid-amended soils.

Benzotriazoles (BTs) and benzotriazole ultraviolet (UV) stabilizers (BUVSs) are commonly used industrial and household chemicals, but little is known about their dissipation behavior in the soil environment associated with biosolid application. The authors investigated the occurrence and dissipation of 4 BTs (BT, 5-methyl-1H-benzotriazole [5-TT], 5-chloro-1H-benzotriazole [CBT], and 5,6-dimethyl-1H-benzotriazole [XT]) and 5 BUVSs (UV-326, UV-327, UV-328, UV-329, and UV-P) in biosolid-amended soil of 3 trial sites (Zhejiang, Hunan, and Shandong) in China following 2 treatments (treatment 1: a single application of biosolid; treatment 2: repeated application of biosolid). The results showed that except for CBT and XT, the other 7 compounds could be detected in most of the biosolid and biosolid-amended soils at levels of a few to tens of nanograms per gram and that the concentrations of the 7 compounds for treatment 2 were obviously higher than those for treatment 1. In the 1-yr monitoring of the Shandong site, 2 BTs (BT and 5-TT) and 5 BUVSs (UV-326, UV-327, UV-328, UV-329, and UV-P) were significantly dissipated in the biosolid-amended soils. The field half-lives of BT and 5-TT ranged from 217 d to 345 d, while those for the BUVSs ranged between 75 d and 218 d. The field half-lives of target compounds in soil were found to be comparable to the modeling results. The results suggest the persistence of BTs and BUVSs in soil environments with quite slow dissipation rates.

Biotransformation of the flame retardant tetrabromobisphenol-A (TBBPA) by freshwater microalgae.

Tetrabromobisphenol-A (TBBPA) is the most widely used brominated flame retardant. However, little is known about its biotransformation by algae in aquatic environments. The authors investigated transformations of TBBPA by 6 freshwater green microalgae and identified its transformation products. Transformation experiments were conducted under axenic conditions in a laboratory for 10 d. The results showed that TBBPA could be transformed by the selected microalgae, with nearly complete removal by Scenedesmus quadricauda and Coelastrum sphaericum following 10-d incubation. Five transformation products were positively identified by mass spectrometry: TBBPA sulfate, TBBPA glucoside, sulfated TBBPA glucoside, TBBPA monomethyl ether, and tribromobisphenol-A. The mechanisms involved in the biotransformation of TBBPA include sulfation, glucosylation, O-methylation, and debromination, which could be an important step for its further degradation. This suggests that microalgae can play an important role in the fate of TBBPA in aquatic environments. The present study is the first report on algal transformation of TBBPA, and the proposed transformation products could have significant environmental implications.

Photodegradation of the azole fungicide fluconazole in aqueous solution under UV-254: kinetics, mechanistic investigations and toxicity evaluation.

The azole fungicide fluconazole has been reported to be persistent in conventional wastewater treatment plants. This study investigated the photodegradation of fluconazole under UV-254 in aqueous solutions. The results revealed that the photodegradation of fluconazole was pH-dependent (2.0-12.0) following the pseudo-first-order kinetics with quantum yield values ranging from 0.023 to 0.090 mol einstein(-1), and it underwent a direct and self-sensitized mechanism involving (1)O2. The main photodegradation by-products were identified and semi-quantitated. The proposed photodegradation pathway included hydroxylative defluorination reaction. The 72 h-NOEC and 72 h-LOEC values for fluconazole using a freshwater unicellular green alga Pseudokirchneriella subcapitata were 10 µM and 15 µM. Overall, the photodegradation of fluconazole produced a significant decrease in algal toxicity. It also proved that the photodegradation by-products will not present extra toxicity to this alga than fluconazole itself.

Field dissipation and plant uptake of benzotriazole ultraviolet stabilizers in biosolid-amended soils.

Benzotriazole ultraviolet stabilizers (BUVSs) have been commonly used in industrial and household product formulations, and have been detected in biosolids from wastewater treatment plants. However, little is known about their occurrence and dissipation behavior in the soil environment associated with biosolid application. This study investigated the occurrence and dissipation of five typical BUVSs (UV-326, UV-327, UV-328, UV-329 and UV-P) in biosolid-amended soils, and the uptake of these biocides by plants. The field trial includes two treatment groups: old groups with biosolid application at rates of 5, 10, 20 and 40 t ha(-1) every year within 5 years, and new groups with only one biosolid application. The results showed that the five BUVSs could be detected in most biosolid-amended soils at a few to tens of ng g(-1) levels, but not detected in the control soils. These chemicals were not found in the crop plants collected from the trial plots. Moreover, high biosolid application rates and repeated biosolid applications resulted in high accumulation of these BUVSs in soil. During one year monitoring, the five BUVSs were significantly dissipated in the biosolid-amended soils with their half-lives ranging from 79 to 223 days, which were comparable with the modeling results. The results from this study demonstrated the persistence of BUVSs in soil environments with quite slow dissipation rates.

Biotransformation of progesterone and norgestrel by two freshwater microalgae (Scenedesmus obliquus and Chlorella pyrenoidosa): transformation kinetics and products identification.

Natural and synthetic steroid hormones such as progesterone and norgestrel in the aquatic environment may cause adverse effects on aquatic organisms. This study investigated the biotransformation of progesterone and norgestrel in aqueous solutions by two freshwater microalgae Scenedesmus obliquus and Chlorella pyrenoidosa and elucidated their transformation mechanisms. More than 95% of progesterone was transformed by the two microalgae within 5d. For norgestrel, almost complete transformation by S. obliquus was observed after 5 d, but nearly 40% was remained when incubated with C. pyrenoidosa. The results also showed that these two compounds were not accumulated in the algal cells. Biotransformation was found to be the main mechanism for their loss in the aqueous solutions, and it followed the first-order kinetic model. For progesterone, three main transformation products, i.e. 3ß-hydroxy-5α-pregnan-20-one, 3,20-allopregnanedione and 1,4-pregnadiene-3,20-dione, and six minor androgens were identified. For norgestrel, only two transformation products, 4,5-dihydronorgestrel and 6,7-dehydronorgestrel, were identified for the first time. Hydroxylation, reduction and oxidation are proposed to be the main transformation pathways. Among the two microalgae species, S. obliquus was found more efficient in the transformation of the two target compounds than C. pyrenoidosa. The results clearly demonstrated the capability of the two microalgae to transform the two progestogens. The biotransformation and products could have significant environmental implications in the fate and effects of the two steroids.

Field dissipation and risk assessment of typical personal care products TCC, TCS, AHTN and HHCB in biosolid-amended soils.

The antimicrobial agents triclocarban (TCC) and triclosan (TCS) and synthetic musks AHTN (Tonalide) and HHCB (Galaxolide) are widely used in many personal care products. These compounds may release into the soil environment through biosolid application to agricultural land and potentially affect soil organisms. This paper aimed to investigate accumulation, dissipation and potential risks of TCC, TCS, AHTN and HHCB in biosolid-amended soils of the three field trial sites (Zhejiang, Hunan and Shandong) with three treatments (CK: control without biosolid application, T1: single biosolid application, T2: repeated biosolid application every year). The one-year monitoring results showed that biosolids application could lead to accumulation of these four chemicals in the biosolid-amended soils, with the residual concentrations in the following order: TCC>TCS>AHTN>HHCB. Dissipation of TCC, TCS, AHTN and HHCB in the biosolid-amended soils followed the first-order kinetics model. Half-lives for TCC, TCS, AHTN and HHCB under the field conditions of Shandong site were 191, 258, 336 and 900 days for T1, and 51, 106, 159 and 83 days for T2, respectively. Repeated applications of biosolid led to accumulation of these personal care products and result in higher ecological risks. Based on the residual levels in the trial sites and limited toxicity data, high risks to soil organisms are expected for TCC and TCS, while low-medium risks for AHTN and HHCB.

Typical azole biocides in biosolid-amended soils and plants following biosolid applications.

Biosolid application on agricultural land may contaminate soils with various household chemicals and personal care products. This study investigated the occurrence and dissipation of typical azole biocides climbazole, clotrimazole, and miconazole in biosolid-amended soils as well as the uptake of these biocides by plants. The field trial includes two treatment groups: old groups with biosolid application at rates of 5, 10, 20, and 40 t/ha every year within 5 years, and new groups with only one biosolid application. The results showed that climbazole, clotrimazole, and miconazole were detected in biosolid-amended soils, but not detected in control soils. These biocides were not found in the crop plants collected from the trial plots. The dissipation half-lives for climbazole, clotrimazole, and miconazole under the field conditions were 175-179, 244, and 130-248 days, respectively. High biosolid application rates and repeated biosolid applications could lead to higher persistence of the biocides in the agricultural soils. An exposure model could effectively predict the residual concentrations of climbazole and miconazole in the biosolid-amended soils of the old treatments with different biosolid application rates. Thus, the field trial demonstrated high persistence of these three biocides in the soil environments.

Occurrence and dissipation of three azole biocides climbazole, clotrimazole and miconazole in biosolid-amended soils.

This study investigated the occurrence and dissipation of three azole biocides climbazole, clotrimazole and miconazole in biosolid-amended soils of the three sites (Zhejiang, Hunan and Shandong) in China following three treatments (CK: control without biosolid application; T1: one biosolid application; T2: biosolid application every year). The results showed that climbazole, clotrimazole and miconazole were present in the biosolid and biosolid-amended soils, but absent in the control soils. In the soils treated with biosolids, the concentrations of climbazole, clotrimazole and miconazole were mostly lower in the Zhejiang soils than in the Shandong or Hunan soils, suggesting that these three biocides are more readily dissipated under the flooding condition. During the one year monitoring, the concentrations of climbazole, clotrimazole and miconazole in the biosolid-applied soils showed only slight variations. The dissipation half-lives for miconazole calculated under the field conditions of Shandong site were 440 days for T1 and the half-lives for clotrimazole were 365 days for T2. The results suggested the persistence of these three biocides in the soil environments.

Occurrence and fate of eleven classes of antibiotics in two typical wastewater treatment plants in South China.

Wastewater treatment plants (WWTPs) are regarded as one of the most important sources of antibiotics in the environment. Two sampling campaigns over a period of one year in two wastewater treatment plants (plant A: activated sludge with chlorination, and plant B: oxidation ditch with UV) of Guangdong Province, China were carried out to assess the occurrence and fate of 11 classes of 50 antibiotics. The wastewater samples were extracted by Oasis HLB cartridges (6mL, 500 mg), while the solid samples (sludge and suspended solid matter) were extracted by ultrasonic-assisted extraction with solvents (acetonitrile and citric acid buffer), followed by an enrichment and clean-up step with solid-phase extraction using SAX-HLB cartridges in tandem. The results showed the presence of 20 and 17 target compounds in the influents and effluents, respectively, at the concentrations ranging from low ng/L to a few µg/L. Sulfamethoxazole, norfloxacin, ofloxacin, anhydro erythromycin and trimethoprim were most frequently detected in the WWTPs wastewaters. Twenty-one antibiotics were found in the sewage sludge from the two WWTPs at the concentrations up to 5800ng/g, with tetracycline, oxytetracycline, norfloxacin and ofloxacin being the predominant antibiotics. The total mass loads of antibiotics per capita in the two plants ranged from 494 to 901 µg/d/inhabitant (672±182 µg/d/inhabitant) in the influents, from 130 to 238 µg/d/inhabitant (175±45 µg/d/inhabitant) in the effluents and from 107 to 307 µg/d/inhabitant (191±87.9 µg/d/inhabitant) in the dewatered sludge, respectively. The aqueous removals for sulfonamides, macrolides, trimethoprim, lincomycin and chloramphenicol in the WWTPs were mainly attributed to the degradation processes, while those for tetracyclines and fluoroquinolones were mainly due to the adsorption onto sludge.

Use patterns, excretion masses and contamination profiles of antibiotics in a typical swine farm, south China.

The objective of this study was to screen the occurrence of 50 antibiotics in a typical swine farm in southern China, which includes animal feeds, waste collection and treatment systems (lagoons and anaerobic digesters), and receiving environments (vegetable fields, streams, and private wells). Nine antibiotics were found in the feeds for different stages of the development of pigs in the swine farm, at concentrations ranging from 2.37 ± 0.16 ng g(-1) (sulfamethazine) to 61 500 ± 11 900 ng g(-1) (bacitracin). 11, 17 and 15 target compounds were detected in feces, flush water, and suspended particles in the swine farm, respectively. Based on the survey of feeds and animal waste from the farm, chlortetracycline, tetracycline, bacitracin and florfenicol in the feces, flush water and suspended particles mainly originated from the feeds, while most sulfonamides, including doxycycline, oxytetracycline, fluoroquinolones, macrolides and trimethoprim, were mainly from injection and other oral routes. The daily excretion masses of antibiotics per pig calculated based on animal waste had the following order: sows (48.3 mg per day per pig), piglets (18.9 mg per day per pig), growing pigs (7.01 mg per day per pig) and finishing pigs (1.47 mg per day per pig), indicating that the usage of antibiotics (type and dosage) and excretion masses are related to the growth stage of pigs. Chlortetracycline and bacitracin are the main contributors to the total excretion mass of antibiotics from pigs at different stages of development in the farm. The waste treatment system (lagoons and anaerobic digesters) was found to be ineffective in the elimination of antibiotics. The detection of some antibiotics in the surrounding environments of the farm (the well water, stream water and vegetable field soil) was a reflection of pollution from the swine farm.