Oxylipin profiling by LC-ESI-MS/MS in canine serum and plasma to investigate ovulation-specific changes.

New biomarkers that are directly associated with canine ovulation would be of value to ensure mating on optimal days of heat. In this study, canine plasma and serum were analyzed with liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to quantify a broad range of oxylipins for the purpose of developing a method for biomarker discovery studies in canine reproduction. A majority of the 67 oxylipins probed for were detected at comparable levels in both sample types, but more oxylipins at higher concentrations were detected in serum than in plasma. Nine of the oxylipins were detected in a pilot study of serum at levels that significantly differed (p ≤ 0.1) between time-points before (n = 10), during (n = 10) and after (n = 10) ovulation, and might serve as putative biomarkers for canine ovulation. One oxylipin (20-HETE) was significantly altered after adjusting for multiple comparisons. In conclusion, the results showed that the LC-ESI-MS/MS method was suitable for quantification of canine oxylipins, revealing important similarities and differences between plasma and serum profiles as well as preliminary ovulation-specific changes in a subset of the investigated oxylipins.

Effects of conventionally treated and ozonated wastewater on the damselfly larva oxylipidome in response to on-site exposure.

Pharmaceutical residues discharged through insufficiently treated or untreated wastewater enter aquatic environments, where they may adversely impact organisms such as aquatic invertebrates. Ozonation, an advanced wastewater treatment technique, has been successfully implemented to enhance the removal of a broad range of pharmaceuticals, however diverse byproducts and transformation products that are formed during the ozonation process make it difficult to predict how ozonated wastewater may affect aquatic biota. The aim of this study was to investigate effects on fatty acid metabolites, oxylipins, in a common invertebrate species, damselfly larvae, after on-site exposure to conventional wastewater treatment plant (WWTP) effluent and additionally ozonated effluent at a full-scale WWTP. Subsequent ozonation of the conventionally treated wastewater was assessed in terms of i) removal of pharmaceuticals and ii) potential sub-lethal effects on the oxylipidome. Northern damselfly (Coenagrion hastulatum) larvae were exposed for six days in the treatment plant facility to either conventional WWTP effluent or ozonated effluent and the effects on pharmaceutical levels and oxylipin levels were compared with those from tap water control exposure. Ozonation removed pharmaceuticals at an average removal efficiency of 67% (ozone dose of 0.49 g O3/g DOC). Of 38 pharmaceuticals detected in the effluent, 16 were removed to levels below the limit of quantification by ozonation. Levels of two oxylipins, 12(13)-EpODE and 15(16)-EpODE, were reduced in larvae exposed to the conventionally treated wastewater in comparison to the tap water control. 15(16)-EpODE was reduced in the larvae exposed to ozonated effluent in comparison to the tap water control. One oxylipin, 8-HETE, was significantly lower in larvae exposed to conventional WWTP effluent compared to ozonated effluent. In conclusion, the study provides proof-of-principle that damselfly larvae can be used on-site to test the impact of differentially treated wastewater.

Feasibility and reliability of measures of bioactive lipids in human plasma and nasal mucosa.

Analysis of bioactive lipids is increasingly useful in clinical studies, and there is a need for non-invasive and easy-to-use sampling methods that meet the demands of reliability. Samples that can be taken by a non-professional and that can be taken repeatedly so as to provide more detailed information about the inflammatory process are often desired. In this study, the feasibility of non-invasive sampling of nasal mucosa and saliva for the analysis of bioactive lipid mediators (e.g. oxylipins and endocannabinoids) was evaluated in a pilot study (n = 10). In a second study, the reliability (relative and absolute) of sampling of these lipid mediators derived from nasal mucosa and from plasma was assessed by calculation of the intraclass correlation coefficient and Bland-Altman's limit of agreement. Samples were taken at the same time of day on two occasions from a cohort of individuals with and without building-related intolerance (n = 37). Nasal mucosa proved to be a suitable matrix for the analysis of bioactive lipids and was therefore included in the study on reliability together with the plasma samples. Relative reliability varied among the identified oxylipins and endocannabinoids. Arachidonic acid derivatives showed generally better reliability. Absolute reliability measures also varied indicating that only a subset of the oxylipins and endocannabinoids were suitable as biomarkers in either nasal mucosa or plasma and should therefore be used with caution for that purpose.

On-Site Pilot Testing of Hospital Wastewater Ozonation to Reduce Pharmaceutical Residues and Antibiotic-Resistant Bacteria.

Hospital sewage constitutes an important point source for antibiotics and antibiotic-resistant bacteria due to the high antibiotic use. Antibiotic resistance can develop and cause problems in sewage systems within hospitals and municipal wastewater treatment plants, thus, interventions to treat hospital sewage on-site are important. Ozonation has proven effective in treating relatively clean wastewater, but the effect on untreated wastewater is unclear. Therefore, we piloted implementation of ozonation to treat wastewater in a tertiary hospital in Uppsala, Sweden. We measured active pharmaceutical ingredients (APIs) using liquid chromatography-mass spectrometry and antibiotic-resistant Enterobacteriaceae using selective culturing pre- and post-ozonation. Comparing low (1 m3/h) and high (2 m3/h) flow, we obtained a 'dose-dependent' effect of API reduction (significant reduction of 12/29 APIs using low and 2/29 APIs using high flow, and a mean reduction of antibiotics of 41% using low vs. 6% using high flow, 25% vs. 6% for all APIs). There was no significant difference in the amount of antibiotic-resistant Enterobacteiaceae pre- and post-ozonation. Our results demonstrate that ozonation of untreated wastewater can reduce API content. However, due to the moderate API decrease and numerous practical challenges in the on-site setting, this specific ozonation system is not suitable to implement at full scale in our hospital.

Fate of active pharmaceutical ingredients in a northern high-rate algal pond fed with municipal wastewater.

Active pharmaceutical ingredients (APIs) are vital to human health and welfare, but following therapeutic use, they may pose a potential ecological risk if discharged into the environment. Today's conventional municipal wastewater treatment plants are not designed to remove APIs specifically, and various techniques, preferably cost-effective and environmentally friendly, are being developed and evaluated. Microalgae-based treatment of wastewater is a sustainable and low-cost approach to remove nutrients and emerging contaminants. In this study, a North Sweden high-rate algal pond (HRAP) using municipal untreated wastewater as medium, was investigated in terms of API distribution and fate. Three six-day batches were prepared during 18 days and a total of 36 APIs were quantified within the HRAP of which 14 were removed from the aqueous phase above 50% and seven removed above 90% of their initial concentrations. Twelve APIs of a hydrophobic nature were mostly associated with the algal biomass that was harvested at the end of each batch. HRAPs treatment successfully removed 69% of studied APIs (25 of 36 studied) in six day time. The distribution of various APIs between the aqueous phase and biomass suggested that several removal mechanisms may occur, such as hydrophobicity driven removal, passive biosorption and active bioaccumulation.

Oxylipins at intermediate larval stages of damselfly Coenagrion hastulatum as biochemical biomarkers for anthropogenic pollution.

Aquatic pollution resulting from anthropogenic activities requires adequate environmental monitoring strategies in sentinel organisms. Thus, biochemical biomarkers have been used as early-warning tools of biological effects in aquatic organisms. However, before using these markers for environmental monitoring, knowledge about their developmental variation is vital. In this study, we assessed baseline levels and developmental variations of a group of potential biomarkers, oxylipins, during the lifespan of the Northern damselfly (Coenagrion hastulatum) using liquid chromatography-tandem mass spectrometry. Effects of wastewater exposure on baseline levels were studied in a subset of damselflies to investigate the responsiveness due to anthropogenic pollution. Thirty-eight oxylipins deriving from four polyunsaturated fatty acids via two enzymatic pathways were detected in damselflies at three larval stages and in the adult form. Overall, oxylipin baseline levels showed developmental variation, which was lowest in the intermediate larval stages. Effects of exposure to wastewater effluent on oxylipin baseline levels were dependent on the life stage and were greatest in the early and intermediate larval stages. The study provides first insights into oxylipin profiles of damselflies at different stages of development and their developmental variation. Based on our results, we propose further strategies for incorporating oxylipins in damselfly larvae as biochemical markers for anthropogenic pollution.

Neuroactive drugs and other pharmaceuticals found in blood plasma of wild European fish.

To gain a better understanding of which pharmaceuticals could pose a risk to fish, 94 pharmaceuticals representing 23 classes were analyzed in blood plasma from wild bream, chub, and roach captured at 18 sites in Germany, the Czech Republic and the UK, respectively. Based on read across from humans, we evaluated the risks of pharmacological effects occurring in the fish for each measured pharmaceutical. Twenty-three compounds were found in fish plasma, with the highest levels measured in chub from the Czech Republic. None of the German bream had detectable levels of pharmaceuticals, whereas roach from the Thames had mostly low concentrations. For two pharmaceuticals, four individual Czech fish had plasma concentrations higher than the concentrations reached in the blood of human patients taking the corresponding medication. For nine additional compounds, determined concentrations exceeded 10% of the corresponding human therapeutic plasma concentration in 12 fish. The majority of the pharmaceuticals where a clear risk for pharmacological effects was identified targets the central nervous system. These include e.g. flupentixol, haloperidol, and risperidone, all of which have the potential to affect fish behavior. In addition to identifying pharmaceuticals of environmental concern, the results emphasize the value of environmental monitoring of internal drug levels in aquatic wildlife, as well as the need for more research to establish concentration-response relationships.

Polyunsaturated Fatty Acids and Their Metabolites in Hyperemesis Gravidarum.

Polyunsaturated fatty acids (PUFAs) have been studied in relation to pregnancy. However, there is limited knowledge on PUFAs and their metabolites in relation to hyperemesis gravidarum (HG), a pregnancy complication associated with nutritional deficiencies and excessive vomiting. In order to survey the field, a systematic review of the literature was performed, which also included nausea and vomiting of pregnancy (NVP) due to its close relationship with HG. In the very few published studies found, the main subjects of the research concerned free fatty acids (four records), lipid profiles (three records), and bioactive lipids (one article about prostaglandin E2 and one about endocannabinoids). The authors of these studies concluded that, although no cause-and-effect relationship can be established, HG is linked to increased sympathetic responsiveness, thermogenic activity and metabolic rate. In addition, NVP is linked to a metabolic perturbance (which lasts throughout pregnancy). The low number of retrieved records underlines the need for more research in the area of PUFAs and HG, especially with regard to the underlying mechanism for the detected effects, potentially involving growth differentiation factor 15 (GDF15) since evidence for GDF15 regulation of lipid metabolism and the role for GDF15 and its receptor in nausea and vomiting is emerging.

Quantification of total concentration of thiol functional groups in environmental samples by titration with monobromo(trimethylammonio)bimane and determination with tandem mass spectrometry.

Thiol compounds (R-SH) have many important biological functions and are principal controls of the speciation of several toxic metals in the environment. However, determining the concentration of thiols associated with environmental matrices is challenging due to the compounds' low abundance and interferences from non-thiol compounds for many available methods. Here a novel method has been developed and validated to quantify the total concentration of thiol functional groups in aqueous samples using derivatization with monobromo(trimethylammonio)bimane (qBBr) and quantification with tandem mass spectrometry. The thiol concentration was determined by titration of the sample with qBBr, which reacts selectively with thiols, and quantification of the residual qBBr. We systematically evaluated potential interferences from various organic compounds, inorganic ions (including sea water matrices), sulfide and mercury (Hg) species, and demonstrate that the method is highly sensitive, selective and robust. The limit of detection (LOD) for total thiols is in the nanomolar concentration range (~6 nM). The method performance was also demonstrated by determination of the total thiol concentration in different natural samples including boreal stream water (1.16 µM), wetland porewater (0.96 µM) and the Suwanee River natural organic matter (NOM) reference material SR101 N (7.9 µmol g-1). The developed method represents a combination of low LOD and high selectivity and robustness that is unsurpassed for total thiol concentration measurements.

Extraction of active pharmaceutical ingredients from simulated spent activated carbonaceous adsorbents.

Activated carbon (AC) and activated biochar (ABC) are widely used as sorbents for micropollutant removal during water and wastewater treatment. Spent adsorbents can be treated in several ways, e.g., by incineration, disposal in landfills, or reactivation. Regeneration is an attractive and potentially more economically viable alternative to modern post-treatment practices. Current strategies for assessing the performance of regeneration techniques often involve only repeated adsorption and regeneration cycles, and rarely involve direct measurements of micropollutants remaining on the adsorbent after regeneration. However, the use of regenerated adsorbents containing such residual micropollutants could present an environmental risk. In this study, the extraction of eight active pharmaceutical ingredients (APIs) commonly found in treated effluents was evaluated using 10 solvents and sorption onto three different carbon materials. An optimized extraction method was developed involving ultrasonication in 1:1 methanol:dichloromethane with 5% formic acid. This method achieved recoveries of 60 to 99% per API for an API concentration of 2 µg/g char and 27 to 129% per API for an API concentration of 1 mg/g char. Experiments using a mixture of 82 common APIs revealed that the optimized protocol achieved extraction recoveries above 70% for 29 of these APIs. These results show that the new extraction method could be a useful tool for assessing the regenerative properties of different carbon sorbents.

Novel metabolomic method to assess the effect-based removal efficiency of advanced wastewater treatment techniques.

Unprecedented levels of chemicals of anthropogenic origin are currently released into surface waters globally. Wastewater treatment plant effluent has been identified as a major source, containing a broad mixture of pharmaceuticals and consumer chemicals. Therefore, there is a need for implementation of advanced wastewater treatment techniques, such as ozonation and adsorption methods, to reduce the contamination. However, there are conflicting findings on the toxicity of treated effluent and only limited possibilities for assessing the effect-based removal efficiency (EBRE) of different treatment techniques. Here, we describe a metabolomics approach to detect perturbations in fatty acid catabolic pathways as a proxy for biological effects. Metabolites in three fatty acid pathways were analyzed in a common damselfly larva (Coenagrion hastulatum) by liquid chromatography coupled to mass spectrometry. The larvae were exposed for one week to either conventionally treated effluent (activated sludge treatment), effluent additionally treated with ozone or effluent additionally treated with biochar filtration and results were compared with those from tap water control exposure. Five lipoxygenase-derived oxylipins (9,10,13-TriHOME, 9,12,13-TriHOME, 9-HODE, 9-HOTrE, and 13-HOTrE) decreased in response to conventionally treated effluent exposure. By using an additional treatment step, oxylipin levels were restored with exception of 9,10,13-TriHOME (ozonated effluent), and 9-HOTrE and 13-HOTrE (effluent filtered with biochar). In conclusion, exposure to wastewater effluent affected fatty acid metabolite levels in damselfly larvae, and a subset of the analyzed metabolites may serve as indicators for biological effects in biota in response to effluent exposure. To that effect, our findings suggest a new metabolomics protocol for assessing EBRE.

Influenza A/H4N2 mallard infection experiments further indicate zanamivir as less prone to induce environmental resistance development than oseltamivir.

Neuraminidase inhibitors (NAIs) are the gold standard treatment for influenza A virus (IAV). Oseltamivir is mostly used, followed by zanamivir (ZA). NAIs are not readily degraded in conventional wastewater treatment plants and can be detected in aquatic environments. Waterfowl are natural IAV hosts and replicating IAVs could thus be exposed to NAIs in the environment and develop resistance. Avian IAVs form the genetic basis for new human IAVs, and a resistant IAV with pandemic potential poses a serious public health threat, as NAIs constitute a pandemic preparedness cornerstone. Resistance development in waterfowl IAVs exposed to NAIs in the water environment has previously been investigated in an in vivo mallard model and resistance development was demonstrated in several avian IAVs after the exposure of infected ducks to oseltamivir, and in an H1N1 IAV after exposure to ZA. The N1 and N2 types of IAVs have different characteristics and resistance mutations, and so the present study investigated the exposure of an N2-type IAV (H4N2) in infected mallards to 1, 10 and 100 µg l-1 of ZA in the water environment. Two neuraminidase substitutions emerged, H274N (ZA IC50 increased 5.5-fold) and E119G (ZA IC50 increased 110-fold) at 10 and 100 µg l-1 of ZA, respectively. Reversion towards wild-type was observed for both substitutions in experiments with removed drug pressure, indicating reduced fitness of both resistant viruses. These results corroborate previous findings that the development of resistance to ZA in the environment seems less likely to occur than the development of resistance to oseltamivir, adding information that is useful in planning for prudent drug use and pandemic preparedness.

Stability and uptake of methylphenidate and ritalinic acid in nine-spine stickleback (Pungitius pungitius) and water louse (Asellus aquaticus).

The presence of human pharmaceuticals in the environment has garnered significant research attention because these compounds may exert therapeutic effects on exposed wildlife. Yet, for many compounds, there is still little research documenting their stability in the water column and uptake in organism tissues. Here, we measured the uptake and stability of methylphenidate (Ritalin®, a frequently prescribed central nervous system stimulant) and its primary metabolite, ritalinic acid, in (1) water only or (2) with nine-spine stickleback and water louse. Methylphenidate degraded to ritalinic acid in both studies faster at a higher temperature (20 °C versus 10 °C), with concentrations of ritalinic acid surpassing methylphenidate after 48-100 h, depending on temperature. The concentration of methylphenidate in stickleback was highest at the first sampling point (60 min), while the concentration in water louse tissues reached comparatively higher levels and peaked after ~ 6 days. Neither stickleback nor water louse took up ritalinic acid in tissues despite being present in the water column. Our findings provide valuable data for use in future risk assessment of methylphenidate and will aid in the design of studies aimed at measuring any ecotoxicological effects on, for example, the behaviour or physiology of aquatic organisms.

Northern green algae have the capacity to remove active pharmaceutical ingredients.

Eight recently isolated microalgal species from Northern Sweden and the culture collection strain Scenedesmus obliquus RISE (UTEX 417) were tested for their ability to remove 19 pharmaceuticals from growth medium upon cultivation in short light path, flat panel photobioreactors. While the growth of one algal species, Chlorella sorokiniana B1-1, was completely inhibited by the addition of pharmaceuticals, and the one of Scenedesmus sp. B2-2 was strongly inhibited, the other algal strains grew well and produced biomass. In general, lipophilic compounds were removed highly efficient from the culture medium by the microalgae (>70% in average within 2 days). The most lipophilic compounds Biperiden, Trihexyphenidyl, Clomipramine and Amitriptyline significantly accumulated in the biomass of most algal species, with a positive correlation between accumulation and their total biomass content. More persistent in the growth medium were hydrophilic compounds like Caffeine, Fluconazole, Trimetoprim, Codeine, Carbamazepin, Oxazepam and Tramadol, which were detected in amounts of above 60% in average after algal treatment. While Coelastrella sp. 3-4 and Coelastrum astroideum RW10 were most efficient to accumulate certain compounds in their biomass, two algae species, Chlorella vulgaris 13-1 and Chlorella saccharophila RNY, were not only highly efficient in removing all 19 pharmaceuticals from the growth medium within 12 days, at the same time only small amounts of these compounds accumulated in their biomass allowing its further use. Chlorella vulgaris 13-1 was able to remove most compounds within 6 days of growth, while Chlorella saccharophila RNY needed 8-10 days."Wild" Nordic microalgae therefore are able to remove active pharmaceutical ingredients, equally or more efficient than the investigated culture collection strain, thereby demonstrating their possible use in sustainable wastewater reclamation in Nordic conditions.

Pharmaceutical residues are widespread in Baltic Sea coastal and offshore waters - Screening for pharmaceuticals and modelling of environmental concentrations of carbamazepine.

The consumption of pharmaceuticals worldwide coupled with modest removal efficiencies of sewage treatment plants have resulted in the presence of pharmaceuticals in aquatic systems globally. In this study, we investigated the environmental concentrations of a selection of 93 pharmaceuticals in 43 locations in the Baltic Sea and Skagerrak. The Baltic Sea is vulnerable to anthropogenic activities due to a long turnover time and a sensitive ecosystem in the brackish water. Thirty-nine of 93 pharmaceuticals were detected in at least one sample, with concentrations ranging between 0.01 and 80 ng/L. One of the pharmaceuticals investigated, the anti-epileptic drug carbamazepine, was widespread in coastal and offshore seawaters (present in 37 of 43 samples). In order to predict concentrations of pharmaceuticals in the sub-basins of the Baltic Sea, a mass balance-based grey box model was set up and the persistent, widely used carbamazepine was selected as the model substance. The model was based on hydrological and meteorological sub-basin characteristics, removal data from smaller watersheds and wastewater treatment plants, and statistics relating to population, consumption and excretion rate of carbamazepine in humans. The grey box model predicted average environmental concentrations of carbamazepine in sub-basins with no significant difference from the measured concentrations, amounting to 0.57-3.2 ng/L depending on sub-basin location. In the Baltic Sea, the removal rate of carbamazepine in seawater was estimated to be 6.2 10-9 s-1 based on a calculated half-life time of 3.5 years at 10 °C, which demonstrates the long response time of the environment to measures phasing out persistent or slowly degradable substances such as carbamazepine. Sampling, analysis and grey box modelling were all valuable in describing the presence and removal of carbamazepine in the Baltic Sea.

Screening of biocides, metals and antibiotics in Swedish sewage sludge and wastewater.

Incoming sewage water, treated effluent and digested sludge were collected from 11 Swedish sewage treatment plants (STPs) on 3 different days. Analytical protocols were established for a large number of compounds (47) with antimicrobial properties and the collected samples were then screened for the presence of these selected substances. Liquid chromatography tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to analyse the samples. Thirty organic compounds and 10 metals were detected above their respective detection limit. Quaternary ammonium compounds were the most abundant substances in the particulate phases with levels up to 370 µg/g and benzotriazoles were the most common in the aqueous phases with levels up to 24 µg/L. Several compounds with no, or very limited, previously reported data were detected in this study, including chlorhexidine, hexadecylpyridinium chloride and 10-benzalkonium chloride. Some of these were both frequently detected (>60% detection frequency) and found in high levels (up to 19 µg/g d.w. sludge). This study gives a comprehensive overview of the presence in Swedish STPs of a number of antimicrobial substances, providing crucial information in designing relevant studies on potential microbial co- and cross resistance development between antibiotics, biocides, and metals in the sewage system.

Removal of pharmaceuticals and unspecified contaminants in sewage treatment effluents by activated carbon filtration and ozonation: Evaluation using biomarker responses and chemical analysis.

Traces of active pharmaceutical ingredients (APIs) and other chemicals are demonstrated in effluents from sewage treatment plants (STPs) and they may affect quality of surface water and eventually drinking water. Treatment of effluents with granular activated carbon (GAC) or ozone to improve removal of APIs and other contaminants was evaluated at two Swedish STPs, Käppala and Uppsala (88 and 103 APIs analyzed). Biomarker responses in rainbow trout exposed to regular and additionally treated effluents were determined. GAC and ozone treatment removed 87-95% of the total concentrations of APIs detected. In Käppala, GAC removed 20 and ozonation (7 g O3/m3) 21 of 24 APIs detected in regular effluent. In Uppsala, GAC removed 25 and ozonation (5.4 g O3/m3) 15 of 25 APIs detected in effluent. GAC and ozonation also reduced biomarker responses caused by unidentified pollutants in STP effluent water. Elevated ethoxyresorufin-O-deethylase (EROD) activity in gills was observed in fish exposed to effluent in both STPs. Gene expression analysis carried out in Käppala showed increased concentrations of cytochrome P450 (CYP1As and CYP1C3) transcripts in gills and of CYP1As in liver of fish exposed to effluent. In fish exposed to GAC- or ozone-treated effluent water, gill EROD activity and expression of CYP1As and CYP1C3 in gills and liver were generally equal to or below levels in fish held in tap water. The joint application of chemical analysis and sensitive biomarkers proved useful for evaluating contaminant removal in STPs with new technologies.

Online solid phase extraction liquid chromatography using bonded zwitterionic stationary phases and tandem mass spectrometry for rapid environmental trace analysis of highly polar hydrophilic compounds - Application for the antiviral drug Zanamivir.

Zanamivir (Za) is a highly polar and hydrophilic antiviral drug used for the treatment of influenza A viruses. Za has been detected in rivers of Japan and it's environmental occurrence has the risk of inducing antiviral resistant avian influenza viruses. In this study, a rapid automated online solid phase extraction liquid chromatography method using bonded zwitterionic stationary phases and tandem mass spectrometry (SPE/LC-MS/MS) for trace analysis of Za was developed. Furthermore, an internal standard (IS) calibration method capable of quantifying Za in Milli-Q, surface water, sewage effluent and sewage influent was evaluated. Optimum pre-extraction sample composition was found to be 95/5 v/v acetonitrile/water sample and 1% formic acid. The developed method showed acceptable linearities (r(2)≥0.994), filtration recovery (≥91%), and intra-day precisions (RSD≤16%), and acceptable and environmentally relevant LOQs (≤20ngL(-1)). Storage tests showed no significant losses of Za during 20 days and +4/-20°C (≤12%) with the exception of influent samples, which should be kept at -20°C to avoid significant Za losses. The applicability of the method was demonstrated in a study on phototransformation of Za in unfiltered and filtered surface water during 28 days of artificial UV irradiation exposure. No significant (≤12%) phototransformation was found in surface water after 28 days suggesting a relatively high photostability of Za and that Za should be of environmental concern.

Abundance and dynamics of antibiotic resistance genes and integrons in lake sediment microcosms.

Antibiotic resistance in bacteria causing disease is an ever growing threat to the world. Recently, environmental bacteria have become established as important both as sources of antibiotic resistance genes and in disseminating resistance genes. Low levels of antibiotics and other pharmaceuticals are regularly released into water environments via wastewater, and the concern is that such environmental contamination may serve to create hotspots for antibiotic resistance gene selection and dissemination. In this study, microcosms were created from water and sediments gathered from a lake in Sweden only lightly affected by human activities. The microcosms were exposed to a mixture of antibiotics of varying environmentally relevant concentrations (i.e., concentrations commonly encountered in wastewaters) in order to investigate the effect of low levels of antibiotics on antibiotic resistance gene abundances and dynamics in a previously uncontaminated environment. Antibiotic concentrations were measured using liquid chromatography-tandem mass spectrometry. Abundances of seven antibiotic resistance genes and the class 1 integron integrase gene, intI1, were quantified using real-time PCR. Resistance genes sulI and ermB were quantified in the microcosm sediments with mean abundances 5 and 15 gene copies/10(6) 16S rRNA gene copies, respectively. Class 1 integrons were determined in the sediments with a mean concentration of 3.8 × 10(4) copies/106 16S rRNA gene copies. The antibiotic treatment had no observable effect on antibiotic resistance gene or integron abundances.