Pesticide screening of surface water and soil along the Mekong River in Cambodia.

Widespread use of pesticides globally has led to serious concerns about environmental contamination, particularly with regard to aquatic and soil ecosystems. This work involved investigating concentrations of 64 pesticides in surface-water and soil samples collected in four provinces along the Mekong River in Cambodia during the dry and rainy seasons (276 samples in total), and conducting semi-structured interviews with local farmers about pesticide use. Furthermore, an ecological risk assessment of the detected pesticides was performed. In total, 56 pesticides were detected in surface water and 43 in soil, with individual pesticides reaching maximum concentrations of 1300 ng/L in the surface-water samples (tebufenozide) and 1100 ng/g dry weight in the soil samples (bromophos-ethyl). The semi-structured interviews made it quite evident that the instructions that farmers are provided regarding the use of pesticides are rudimentary, and that overuse is common. The perceived effect of pesticides was seen as an end-point, and there was a limited process of optimally matching pesticides to pests and crops. Several pesticides were used regularly on the same crop, and the period between application and harvest varied. Risk analysis showed that bromophos-ethyl, dichlorvos, and iprobenfos presented a very high risk to aquatic organisms in both the dry and rainy seasons, with risk quotient values of 850 for both seasons, and of 67 in the dry season and 78 in the rainy season for bromophos-ethyl, and 49 in the dry season and 16 in the rainy season for dichlorvos. Overall, this work highlights the occurrence of pesticide residues in surface water and soil along the Mekong River in Cambodia, and emphasizes the urgent need for monitoring and improving pesticide practices and regulations in the region.

What is in the fish? Collaborative trial in suspect and non-target screening of organic micropollutants using LC- and GC-HRMS.

A collaborative trial involving 16 participants from nine European countries was conducted within the NORMAN network in efforts to harmonise suspect and non-target screening of environmental contaminants in whole fish samples of bream (Abramis brama). Participants were provided with freeze-dried, homogenised fish samples from a contaminated and a reference site, extracts (spiked and non-spiked) and reference sample preparation protocols for liquid chromatography (LC) and gas chromatography (GC) coupled to high resolution mass spectrometry (HRMS). Participants extracted fish samples using their in-house sample preparation method and/or the protocol provided. Participants correctly identified 9-69 % of spiked compounds using LC-HRMS and 20-60 % of spiked compounds using GC-HRMS. From the contaminated site, suspect screening with participants' own suspect lists led to putative identification of on average ∼145 and ∼20 unique features per participant using LC-HRMS and GC-HRMS, respectively, while non-target screening identified on average ∼42 and ∼56 unique features per participant using LC-HRMS and GC-HRMS, respectively. Within the same sub-group of sample preparation method, only a few features were identified by at least two participants in suspect screening (16 features using LC-HRMS, 0 features using GC-HRMS) and non-target screening (0 features using LC-HRMS, 2 features using GC-HRMS). The compounds identified had log octanol/water partition coefficient (KOW) values from -9.9 to 16 and mass-to-charge ratios (m/z) of 68 to 761 (LC-HRMS and GC-HRMS). A significant linear trend was found between log KOW and m/z for the GC-HRMS data. Overall, these findings indicate that differences in screening results are mainly due to the data analysis workflows used by different participants. Further work is needed to harmonise the results obtained when applying suspect and non-target screening approaches to environmental biota samples.

Temporal trends of lipophilic organic contaminants in blue mussel (1994-2017) and eelpout (1994-2017) from the southern Baltic Sea.

A time-trend study was carried out for two important Baltic Sea species, blue mussel (1994-2017, 11 samples) and eelpout (1994-2017, 11 samples), to track the changes in levels of regulated persistent organic pollutants (POPs) and show potential increases in the levels of the contaminants of emerging concern (CECs). It was carried out utilizing gas chromatography-high-resolution mass spectrometry (GC-HRMS) based non-target screening (NTS). Data were acquired in two modes - electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) - to widen the contaminant coverage, and treated using a fast semi-automated NTS data processing workflow. The study revealed that >250 tentatively identified compounds show statistically significant temporal trends in Baltic blue mussel and eelpout. A large number of regulated substances, including but not limited to PCBs, DDTs and other organochlorine pesticides (OCPs), chlorobenzenes, and many polybrominated diphenyl ethers (PBDEs), showed significant declining trends, as was expected. Their rates of decline were in good agreement with previously reported data. In contrast, increasing trends were observed for many CECs, some polycyclic aromatic compounds (PAHs), and hydrocarbons. The CEC group included, among others, four compounds, namely, one personal care product ingredient, 2-ethylhexyl stearate, one brominated compound 1,2,3,5-tetrabromobenzene and two intermediates 4-isopropoxyaniline and bilobol dimethyl ether, that were reported in marine biota for the first time to the best of our knowledge. Several compounds, including four CECs and two unknown brominated compounds, showed levels considerably higher than the common legacy pollutants (CB-153 and BDE-99), which might be taken into consideration for future monitoring and risk assessment. In addition, this work revealed the presence of a plethora of organoiodinated compounds that exhibited statistically significant temporal trends in the samples under study, which could be of future interest.

The NORMAN Suspect List Exchange (NORMAN-SLE): facilitating European and worldwide collaboration on suspect screening in high resolution mass spectrometry.

Background: The NORMAN Association (https://www.norman-network.com/) initiated the NORMAN Suspect List Exchange (NORMAN-SLE; https://www.norman-network.com/nds/SLE/) in 2015, following the NORMAN collaborative trial on non-target screening of environmental water samples by mass spectrometry. Since then, this exchange of information on chemicals that are expected to occur in the environment, along with the accompanying expert knowledge and references, has become a valuable knowledge base for "suspect screening" lists. The NORMAN-SLE now serves as a FAIR (Findable, Accessible, Interoperable, Reusable) chemical information resource worldwide. Results: The NORMAN-SLE contains 99 separate suspect list collections (as of May 2022) from over 70 contributors around the world, totalling over 100,000 unique substances. The substance classes include per- and polyfluoroalkyl substances (PFAS), pharmaceuticals, pesticides, natural toxins, high production volume substances covered under the European REACH regulation (EC: 1272/2008), priority contaminants of emerging concern (CECs) and regulatory lists from NORMAN partners. Several lists focus on transformation products (TPs) and complex features detected in the environment with various levels of provenance and structural information. Each list is available for separate download. The merged, curated collection is also available as the NORMAN Substance Database (NORMAN SusDat). Both the NORMAN-SLE and NORMAN SusDat are integrated within the NORMAN Database System (NDS). The individual NORMAN-SLE lists receive digital object identifiers (DOIs) and traceable versioning via a Zenodo community (https://zenodo.org/communities/norman-sle), with a total of > 40,000 unique views, > 50,000 unique downloads and 40 citations (May 2022). NORMAN-SLE content is progressively integrated into large open chemical databases such as PubChem (https://pubchem.ncbi.nlm.nih.gov/) and the US EPA's CompTox Chemicals Dashboard (https://comptox.epa.gov/dashboard/), enabling further access to these lists, along with the additional functionality and calculated properties these resources offer. PubChem has also integrated significant annotation content from the NORMAN-SLE, including a classification browser (https://pubchem.ncbi.nlm.nih.gov/classification/#hid=101). Conclusions: The NORMAN-SLE offers a specialized service for hosting suspect screening lists of relevance for the environmental community in an open, FAIR manner that allows integration with other major chemical resources. These efforts foster the exchange of information between scientists and regulators, supporting the paradigm shift to the "one substance, one assessment" approach. New submissions are welcome via the contacts provided on the NORMAN-SLE website (https://www.norman-network.com/nds/SLE/). Supplementary Information: The online version contains supplementary material available at 10.1186/s12302-022-00680-6.

Comprehensive non-target screening of biomagnifying organic contaminants in the Baltic Sea food web.

High-resolution mass spectrometry (HRMS) based non-target screening (NTS) is a powerful approach for the simultaneous determination of multiple environmental contaminant classes in complex biota samples. In this study, trophic biomagnification factor (TMF) directed NTS was performed to find and (tentatively) identify known, emerging, and new chemical contaminants that are persistent and biomagnify in Baltic Sea biota. The investigated food web included seven species: one filter feeder (blue mussel, Mytilus edulis), two fish (eelpout, Zoarces viviparous; herring, Clupea harengus), two marine mammals (harbor porpoise, Phocoena phocoena; grey seal, Halichoerus grypus) and two birds (guillemot, Uria aalge; white-tailed sea eagle, Haliaeetus albicilla). The NTS procedure included extraction with organic solvent mixtures, two-step high-resolution gel permeation chromatography clean-up, Florisil® fractionation, gas chromatography (GC) HRMS analysis in electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) modes, and NTS data processing. The latter was performed differently for the EI and ECNI data: the EI data were treated using a flexible and highly automated TMF-directed NTS workflow, whereas the ECNI data were treated with a simpler and less automated workflow that specifically screened for brominated compounds. The two workflows collectively revealed biomagnification (statistically significant TMF values) of >250 tentatively identified compounds, including legacy persistent organic pollutants (POPs), such as PCBs and PCB-related compounds, DDT and its metabolites, and organochlorine pesticides (OCPs), contaminants of emerging concern (CECs), and halogenated natural products (HNPs). Among the tentatively identified CECs, nine have not previously been reported in environmental biota samples. These included four polymer additives (used as antioxidants, rubber additives or plasticizers) and two cosmetic product additives (ethyl myristate and isopropyl palmitate). The CECs should be prioritized for future structure verification and quantification using reference standards.

Biomagnification and Temporal Trends of New and Emerging Dechloranes and Related Transformation Products in Baltic Sea Biota.

To enhance knowledge of the environmental distribution and temporal trends of dechloranes and their transformation products (TPs) we performed suspect screening of Baltic Sea biota (eelpout, herring, harbor porpoise, guillemot and white-tailed sea eagle). Evaluation of new and "digitally frozen" gas chromatography/high-resolution mass spectrometry data revealed 31 compounds: five dechloranes (Dechlorane [Mirex], Dechlorane 602, Dechlorane 603, and syn-/anti-Dechlorane Plus [DP]), three isomers, and 23 TPs. Six new Dechlorane 603 TPs and two new DP TPs were detected, including one hydroxy-TP. Some TPs occurred at much higher concentrations than the parent compounds (e.g., Dechlorane 603 TPs were >10-fold more abundant than their parent). Concentrations of contaminants in the most contaminated species (white-tailed sea eagle) changed little over the period 1965-2017. Slow declines were detected for most compounds (median, 2% per year), although concentrations of DP and DP-TPs increased by 1% per year. Ten contaminants biomagnify, and the trophic magnification factors for TPs of Mirex, Dechlorane 602 and Dechlorane 603 (8.2 to 17.8) were similar to the parent compounds (6.6 to 12.4) and higher than that of DP (2.4, nonsignificant). The results are discussed in relation to the current review of DP for potential listing under the Stockholm Convention on POPs.

A time-trend guided non-target screening study of organic contaminants in Baltic Sea harbor porpoise (1988-2019), guillemot (1986-2019), and white-tailed sea eagle (1965-2017) using gas chromatography-high-resolution mass spectrometry.

The rate of decline in regulated persistent organic pollutant (POP) concentrations in Baltic Sea biota has leveled off in recent years, with new contaminants frequently being discovered. There is, therefore, a need for comprehensive approaches to study occurrence and temporal trends of a wide range of environmental contaminants, including legacy POPs, contaminants of emerging concern (CECs), and new contaminants. In the current work, non-target screening (NTS) workflows were developed and used for, to the best of our knowledge, the first time-trend directed NTS of biota using gas chromatography-high-resolution mass spectrometry (GC-HRMS). To maximize contaminant coverage, both electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) were used. The EI data were treated using highly automated workflows to find, prioritize, and tentatively identify contaminants with statistically significant temporal trends. The ECNI data were manually processed and reviewed prior to time-trend analysis. Altogether, more than 300 tentatively identified contaminants were found to have significant temporal trends in samples of Baltic guillemot, harbor porpoise, or white-tailed sea eagle. Significant decreases were found for many regulated chemicals, as could be expected, such as PCBs, polychlorinated terphenyls, chlorobenzenes, toxaphenes, DDT, other organochlorine pesticides, and tri- and tetra- bromodiphenyl ethers (BDEs). The rate of decline of legacy POPs agreed well with data reported from targeted analyses. Significant increases were observed for small polycyclic aromatic hydrocarbons, heptaBDEs, CECs, and terpenes and related compounds. The CECs included, among others, one plasticizer tributyl acetylcitrate (ATBC), two antioxidants 2,6-bis(1,1-dimethylethyl)phenol and 2,6-bis(tert-butyl)-4-(4-morpholinyl-methyl)phenol, and two compounds used in polymer production, trimethyl isocyanurate and 2-mercaptobenzothiazole, which had not previously been reported in biota. Their increased concentrations in biota indicate increased use and release. The increase in ATBC may be linked to increased use of it as a substitute for di-2-ethylhexyl phthalate (DEHP), which has been phased out over the last decade.

Non-targeted screening workflows for gas chromatography-high-resolution mass spectrometry analysis and identification of biomagnifying contaminants in biota samples.

The health of key species in the Baltic region has been impaired by exposure to anthropogenic hazardous substances (AHSs), which accumulate in organisms and are transferred through food chains. There is, thus, a need for comprehensive characterization of the occurrence and accumulation of AHSs in the ecosystem. In this study, we use a non-target screening (NTS) approach for this purpose. A major challenge in NTS of biological samples is the removal of matrix components such as lipids that may interfere with the detection and identification of compounds of interest. Here, we combine gel permeation chromatography with Florisil® column fractionation to achieve sufficient lipid removal for gas chromatography-high-resolution mass spectrometry analysis using electron ionization (EI) and electron capture negative ion chemical ionization (ECNI). In addition, we present new data processing workflows designed to systematically find and identify frequently occurring and biomagnifying AHSs, including known, emerging, and new contaminants. Using these workflows, we discovered a wide range of contaminants in tissue samples from blue mussels, fish, and marine mammals, and calculated their biomagnification factors (BMFs). Compounds with BMFs above 1 for herring and at least one marine mammal included legacy chlorinated pollutants (polychlorinated biphenyls, DDTs, chloro-benzenes/cyclohexanes, chlordanes, toxaphenes, dieldrin), polybrominated diphenyl ethers (PBDEs), and brominated biphenyls. However, there were also several halogenated natural products (halogenated methoxylated brominated diphenyl ethers, 1'-methyl-1,2'-bipyrroles, 1,1'-dimethyl-2,2'-bipyrroles, and the halogenated monoterpene mixed halogenated compound 1) as well as the novel flame retardant Dechlorane 602 and several polycyclic aromatic hydrocarbons, terpenoids, and steroids. The legacy pollutants exhibited the expected biomagnification behavior, demonstrating the utility of the unguided data processing workflow. Graphical abstract.

Bacterial communities as indicators of environmental pollution by POPs in marine sediments.

Decades of intensive discharge from industrial activities into coastal systems has resulted in the accumulation of a variety of persistent organic pollutants (POPs) in marine waters and sediments, having detrimental impacts on aquatic ecosystems and the resident biota. POPs are among the most hazardous chemicals originating from industrial activities due to their biotoxicity and resistance to environmental degradation. Bacterial communities are known to break down many of these aromatic compounds, and different members of naturally occurring bacterial consortia have been described to work in syntrophic association to thrive in heavily contaminated waters and sediments, making them potential candidates as bioindicators of environmental pollution. In this study environmental, sampling was combined with chemical analysis of pollutants and high-resolution sequencing of bacterial communities using Next Generation Sequencing molecular biology tools. The aim of the present study was to describe the bacterial communities from marine sediments containing high loads of POPs and to identify relevant members of the resident microbial communities that may act as bioindicators of contamination. Marine sediments were collected from a coastal bay area of the Baltic Sea historically influenced by intense industrial activity, including metal smelting, oil processing, and pulp and paper production. Different types of POPs were detected at high concentrations. Fiberbank sediments, resulting from historic paper industry activity, were found to harbour a clearly distinct bacterial community including a number of bacterial taxa capable of cellulolytic and dechlorination activities. Our findings indicate that specific members of the bacterial communities thrive under increasing levels of POPs in marine sediments, and that the abundances of certain taxa correlate with specific POPs (or groups), which could potentially be employed in monitoring, status assessment and environmental management purposes.

Will Climate Change Influence Production and Environmental Pathways of Halogenated Natural Products?

Thousands of halogenated natural products (HNPs) pervade the terrestrial and marine environment. HNPs are generated by biotic and abiotic processes and range in complexity from low molecular mass natural halocarbons (nHCs, mostly halomethanes and haloethanes) to compounds of higher molecular mass which often contain oxygen and/or nitrogen atoms in addition to halogens (hHNPs). nHCs have a key role in regulating tropospheric and stratospheric ozone, while some hHNPs bioaccumulate and have toxic properties similar those of anthropogenic-persistent organic pollutants (POPs). Both chemical classes have common sources: biosynthesis by marine bacteria, phytoplankton, macroalgae, and some invertebrate animals, and both may be similarly impacted by alteration of production and transport pathways in a changing climate. The nHCs scientific community is advanced in investigating sources, atmospheric and oceanic transport, and forecasting climate change impacts through modeling. By contrast, these activities are nascent or nonexistent for hHNPs. The goals of this paper are to (1) review production, sources, distribution, and transport pathways of nHCs and hHNPs through water and air, pointing out areas of commonality, (2) by analogy to nHCs, argue that climate change may alter these factors for hHNPs, and (3) suggest steps to improve linkage between nHCs and hHNPs science to better understand and predict climate change impacts.

Differences in chemical composition of indoor air in rooms associated/not associated with building related symptoms.

Building related health effects or symptoms (BRS), known also as sick-building syndrome (SBS), are a phenomenon that is not well understood. In this study, air samples from 51 rooms associated with BRS and 34 control rooms were collected on multi-sorbent tubes and analyzed by a non-target approach using comprehensive two-dimensional gas chromatography and high-resolution mass spectrometry techniques. The large amount of data gathered was analyzed using multivariate statistics (principle component analysis (PCA) and partial least squares (PLS)). This new analysis approach revealed that in rooms where people experienced BRS, petrochemicals and chemicals emitted from plastics were abundant, whereas in rooms where people did not experience BRS, flavor and fragrance compounds were abundant. Among the petrochemicals benzene and 2-butoxyethanol were found in higher levels in rooms where people experienced BRS. The levels of limonene were sometimes in the range of reported odor thresholds, and similarly 3-carene and beta-myrcene were found in higher concentrations in indoor air of rooms where people did not experience BRS. It cannot be ruled out that these compounds may have influenced the perceived air quality. However, the overall variability in air concentrations was large and it was not possible to accurately predict if the air in a particular room could cause BRS or not.

Analysis of volatile organic compounds in indoor environments using thermal desorption with comprehensive two-dimensional gas chromatography and high-resolution time-of-flight mass spectrometry.

Building-related health effects are frequently observed. Several factors have been listed as possible causes including temperature, humidity, light conditions, presence of particulate matter, and microorganisms or volatile organic compounds. To be able to link exposure to specific volatile organic compounds to building-related health effects, powerful and comprehensive analytical methods are required. For this purpose, we developed an active air sampling method that utilizes dual-bed tubes loaded with TENAX-TA and Carboxen-1000 adsorbents to sample two parallel air samples of 4 L each. For the comprehensive volatile organic compounds analysis, an automated thermal desorption comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry method was developed and used. It allowed targeted analysis of approximately 90 known volatile organic compounds with relative standard deviations below 25% for the vast majority of target volatile organic compounds. It also allowed semiquantification (no matching standards) of numerous nontarget air contaminants using the same data set. The nontarget analysis workflow included peak finding, background elimination, feature alignment, detection frequency filtering, and tentative identification. Application of the workflow to air samples from 68 indoor environments at a large hospital complex resulted in a comprehensive volatile organic compound characterization, including 178 single compounds and 13 hydrocarbon groups.

Corrigendum: Effects of Organic Pollutants on Bacterial Communities Under Future Climate Change Scenarios.

[This corrects the article DOI: 10.3389/fmicb.2018.02926.].

Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater.

A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) and phosphorus by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite® and sand over a period of 12 weeks. In total 29 out of the 31 MPs showed removal efficiency >90% by GAC with an average removal of 97 ±â€¯6%. Xylit and lignite were less efficient with an average removal of 80 ±â€¯28% and 68 ±â€¯29%, respectively. The removal efficiency was found to be impacted by the characterization of the sorbents and physicochemical properties of the compounds, as well as the interaction between the sorbents and compounds. For instance, Xylit and lignite performed well for relatively hydrophobic (log octanol/water partition coefficient (Kow) ≥3) MPs, while the removal efficiency of moderately hydrophilic, highly hydrophilic and negatively charged MPs were lower. The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. GAC and sand had limited ability to remove phosphorus (12 ±â€¯27% and 14 ±â€¯2%, respectively), while the calcium-silicate material Polonite® precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.

Bromoanisoles and methoxylated bromodiphenyl ethers in macroalgae from Nordic coastal regions.

Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products (HNPs), some of which have toxic properties similar to those of well-known anthropogenic contaminants. Sixteen species of red, green and brown macroalgae were collected in 2017-2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analyzed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Target compounds were quantified by gas chromatography-low resolution mass spectrometry (GC-LRMS), with qualitative confirmation in selected species by GC-high resolution mass spectrometry (GC-HRMS). Quantified compounds were 2,4-diBA, 2,4,6-triBA, 2'-MeO-BDE68, 6-MeO-BDE47, and two tribromo-MeO-BDEs and one tetrabromo-MeO-BDE with unknown bromine substituent positions. Semiquantitative results for pentabromo-MeO-BDEs were also obtained for a few species by GC-HRMS. Three extraction methods were compared; soaking in methanol, soaking in methanol-dichloromethane, and blending with mixed solvents. Extraction yields of BAs did not differ significantly (p > 0.05) with the three methods and the two soaking methods gave equivalent yields of MeO-BDEs. Extraction efficiencies of MeO-BDEs were significantly lower using the blend method (p < 0.05). For reasons of simplicity and efficiency, the soaking methods are preferred. Concentrations varied by orders of magnitude among species: ∑2BAs 57 to 57 700 and ∑5MeO-BDEs < 10 to 476 pg g-1 wet weight (ww). Macroalgae standing out with ∑2BAs >1000 pg g-1 ww were Ascophyllum nodosum, Ceramium tenuicorne, Ceramium virgatum, Fucus radicans, Fucus serratus, Fucus vesiculosus, Saccharina latissima, Laminaria digitata, and Acrosiphonia/Spongomorpha sp. Species A. nodosum, C. tenuicorne, Chara virgata, F. radicans and F. vesiculosus (Sweden Atlantic only) had ∑5MeO-BDEs >100 pg g-1 ww. Profiles of individual compounds showed distinct differences among species and locations.

The strength in numbers: comprehensive characterization of house dust using complementary mass spectrometric techniques.

Untargeted analysis of a composite house dust sample has been performed as part of a collaborative effort to evaluate the progress in the field of suspect and nontarget screening and build an extensive database of organic indoor environment contaminants. Twenty-one participants reported results that were curated by the organizers of the collaborative trial. In total, nearly 2350 compounds were identified (18%) or tentatively identified (25% at confidence level 2 and 58% at confidence level 3), making the collaborative trial a success. However, a relatively small share (37%) of all compounds were reported by more than one participant, which shows that there is plenty of room for improvement in the field of suspect and nontarget screening. An even a smaller share (5%) of the total number of compounds were detected using both liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). Thus, the two MS techniques are highly complementary. Most of the compounds were detected using LC with electrospray ionization (ESI) MS and comprehensive 2D GC (GC×GC) with atmospheric pressure chemical ionization (APCI) and electron ionization (EI), respectively. Collectively, the three techniques accounted for more than 75% of the reported compounds. Glycols, pharmaceuticals, pesticides, and various biogenic compounds dominated among the compounds reported by LC-MS participants, while hydrocarbons, hydrocarbon derivatives, and chlorinated paraffins and chlorinated biphenyls were primarily reported by GC-MS participants. Plastics additives, flavor and fragrances, and personal care products were reported by both LC-MS and GC-MS participants. It was concluded that the use of multiple analytical techniques was required for a comprehensive characterization of house dust contaminants. Further, several recommendations are given for improved suspect and nontarget screening of house dust and other indoor environment samples, including the use of open-source data processing tools. One of the tools allowed provisional identification of almost 500 compounds that had not been reported by participants.

Comprehensive assessment of organic contaminant removal from on-site sewage treatment facility effluent by char-fortified filter beds.

To remove organic contaminants from wastewater using cost-efficient and currently existing methods, our study investigated char-fortified filter beds for on-site sewage treatment facilities (OSSFs) in a long-term field setting. OSSFs are commonly used in rural and semi-urban areas worldwide to treat wastewater when municipal wastewater treatment is not economically feasible. First, we screened for organic contaminants with gas chromatography and liquid chromatography mass spectrometry-based targeted and untargeted analysis and then we developed quantitative structure-property relationship models to search for key molecular features responsible for the removal of organic contaminants. We identified 74 compounds (24 confirmed by reference standards) including plasticizers, UV stabilizers, fragrances, pesticides, surfactant and polymer impurities, pharmaceuticals and their metabolites, and many biogenic compounds. Sand filters that are used as a secondary step after the septic tank in OSSFs could remove hydrophobic contaminants. The addition of biochar significantly increased the removal of these and a few hydrophilic compounds (Wilcoxon signed-rank test, α = 0.05). Besides hydrophobicity-driven sorption, biodegradation was suggested to be the most important removal pathway in this long-term field application. However, further improvements are necessary to remove very hydrophilic contaminants as they were not removed with sand and biochar-fortified sand.

Effects of Organic Pollutants on Bacterial Communities Under Future Climate Change Scenarios.

Coastal ecosystems are highly dynamic and can be strongly influenced by climate change, anthropogenic activities (e.g., pollution), and a combination of the two pressures. As a result of climate change, the northern hemisphere is predicted to undergo an increased precipitation regime, leading in turn to higher terrestrial runoff and increased river inflow. This increased runoff will transfer terrestrial dissolved organic matter (tDOM) and anthropogenic contaminants to coastal waters. Such changes can directly influence the resident biology, particularly at the base of the food web, and can influence the partitioning of contaminants and thus their potential impact on the food web. Bacteria have been shown to respond to high tDOM concentration and organic pollutants loads, and could represent the entry of some pollutants into coastal food webs. We carried out a mesocosm experiment to determine the effects of: (1) increased tDOM concentration, (2) organic pollutant exposure, and (3) the combined effect of these two factors, on pelagic bacterial communities. This study showed significant responses in bacterial community composition under the three environmental perturbations tested. The addition of tDOM increased bacterial activity and diversity, while the addition of organic pollutants led to an overall reduction of these parameters, particularly under concurrent elevated tDOM concentration. Furthermore, we identified 33 bacterial taxa contributing to the significant differences observed in community composition, as well as 35 bacterial taxa which responded differently to extended exposure to organic pollutants. These findings point to the potential impact of organic pollutants under future climate change conditions on the basal coastal ecosystem, as well as to the potential utility of natural bacterial communities as efficient indicators of environmental disturbance.

Retention-time prediction in comprehensive two-dimensional gas chromatography to aid identification of unknown contaminants.

Comprehensive two-dimensional (2D) gas chromatography (GC×GC) coupled to mass spectrometry (MS, GC×GC-MS), which enhances selectivity compared to GC-MS analysis, can be used for non-directed analysis (non-target screening) of environmental samples. Additional tools that aid in identifying unknown compounds are needed to handle the large amount of data generated. These tools include retention indices for characterizing relative retention of compounds and prediction of such. In this study, two quantitative structure-retention relationship (QSRR) approaches for prediction of retention times (1tR and 2tR) and indices (linear retention indices (LRIs) and a new polyethylene glycol-based retention index (PEG-2I)) in GC × GC were explored, and their predictive power compared. In the first method, molecular descriptors combined with partial least squares (PLS) analysis were used to predict times and indices. In the second method, the commercial software package ChromGenius (ACD/Labs), based on a "federation of local models," was employed. Overall, the PLS approach exhibited better accuracy than the ChromGenius approach. Although average errors for the LRI prediction via ChromGenius were slightly lower, PLS was superior in all other cases. The average deviations between the predicted and the experimental value were 5% and 3% for the 1tR and LRI, and 5% and 12% for the 2tR and PEG-2I, respectively. These results are comparable to or better than those reported in previous studies. Finally, the developed model was successfully applied to an independent dataset and led to the discovery of 12 wrongly assigned compounds. The results of the present work represent the first-ever prediction of the PEG-2I. Graphical abstract ᅟ.

Nontarget Screening and Time-Trend Analysis of Sewage Sludge Contaminants via Two-Dimensional Gas Chromatography-High Resolution Mass Spectrometry.

Nondestructive sample cleanup and comprehensive two-dimensional gas chromatography (GC×GC) high-resolution mass spectrometry (HRMS) analysis generated a massive amount of data that could be used for nontarget screening purposes. We present a data reduction and prioritization strategy that involves time-trend analysis of nontarget data. Sewage sludge collected between 2005 and 2015 in Stockholm (Sweden) was retrieved from an environmental specimen bank, extracted, and analyzed by GC×GC-HRMS. After data alignment features with high blank levels, artifacts and low detection frequency were removed. Features that appeared in four to six out of ten years were reprocessed to fill in gaps. The total number of compounds was reduced by more than 97% from almost 60 000 to almost 1500. The remaining compounds were analyzed for monotonic (log-linear) and nonmonotonic (smoother) time trends. In total, 192 compounds with log-linear trends and 120 compounds with nonmonotonic trends were obtained, respectively. Most compounds described by a log-linear trend exhibited decreasing trends and were traffic-related. Compounds with increasing trends included UV-filters, alkyl-phenols, and flavor and fragrances, which often could be linked to trade statistics. We have shown that nontarget screening and stepwise reduction of data provides a simple way of revealing significant changes in emissions of chemicals in society.