Synthetic surfactants in Swiss sewage sludges: Analytical challenges, concentrations and per capita loads.

Surfactants are high-production-volume chemicals that are among the most abundant organic pollutants in municipal wastewater. In this study, sewage sludge samples of 36 Swiss wastewater treatment plants (WWTPs), serving 32% of the country's population, were analyzed for major surfactant classes by liquid chromatography mass spectrometry (LC-MS). The analyses required a variety of complementary approaches due to different analytical challenges, including matrix effects (which can affect adduct ion formation) and the lack of reference standards. The most abundant contaminants were linear alkylbenzene sulfonates (LAS; weighted mean [WM] concentration of 3700 µg g-1 dry weight), followed by secondary alkane sulfonates (SAS; 190 µg g-1). Alcohol polyethoxylates (AEO; 8.3 µg g-1), nonylphenol polyethoxylates (NPEO; 16 µg g-1), nonylphenol (NP; 3.1 µg g-1), nonylphenol ethoxy carboxylates (NPEC; 0.35 µg g-1) and tert-octylphenol (tert-OP, 1.8 µg g-1) were present at much lower concentrations. This concentration pattern agrees with the production volumes of the surfactants and their fates in WWTPs. Branched AEO homologues dominated over linear homologues, probably due to higher persistence. Sludge concentrations of LAS, SAS, and NP were positively correlated with the residence time in the anaerobic digester. Derivation of the per capita loads successfully revealed potential industrial/commercial emission sources. Comparison of recent versus historic data showed a decrease in NPEO and NP levels by one or two orders of magnitude since their ban in the 1980s. By contrast, LAS still exhibit similar concentrations compared to 30 years ago.

Transformation of short-chain chlorinated paraffins and olefins with the bacterial dehalogenase LinB from Sphingobium Indicum - Kinetic models for the homologue-specific conversion of reactive and persistent material.

Structure, reactivity and physico-chemical properties of polyhalogenated compounds determine their up-take, transport, bio-accumulation, transformation and toxicity and their environmental fate. In technical mixtures of chlorinated paraffins (CPs), these properties are distributed due to the presence of thousands of homologues. We hypothesized that roles of CP dehalogenation reactions, catalyzed by the haloalkane dehalogenase LinB, depend on structural properties of the substrates, e.g. chlorination degree and carbon-chain length. We exposed mixtures of chlorinated undecanes, dodecanes and tridecanes in-vitro to LinB from Sphingobium Indicum bacteria. These single-chain CP-materials also contain small amounts of chlorinated olefins (COs), which can be distinct by mathematical deconvolution of respective mass-spectra. With this procedure, we obtained homologue-specific transformation kinetics of substrates differing in saturation degree, chlorination degree and carbon chain-length. For all homologues, two-stage first-order kinetic models were established, which described the faster conversion of reactive material and the slower transformation of more persistent material. Half-lifes of 0.5-3.2 h and 56-162 h were determined for more reactive and more persistent CP-material. Proportions of persistent material increased steadily from 18 to 67% for lower (Cl6) to higher (Cl11) chlorinated paraffins and olefins. Conversion efficiencies decreased with increasing chlorination degree from 97 to 70%. Carbon-chain length had only minor effects on transformation rates. Hence, the conversion was faster and more efficient for lower-chlorinated material, and slower for higher-chlorinated and longer-chained CPs and COs. Current legislation has banned short-chain chlorinated paraffins (SCCPs) and forced a transition to longer-chain CPs. This may be counterproductive with regard to enzymatic transformation with LinB.

Long-term effects of a catastrophic insecticide spill on stream invertebrates.

Accidental spills or illegal discharges of pesticides in aquatic ecosystems can lead to exposure levels that strongly exceed authorized pesticide concentrations, causing major impacts on aquatic ecosystems. Such short-term events often remain undetected in regular monitoring programs with infrequent sampling. In early spring 2015, we identified a catastrophic pesticide spill with the insecticide cypermethrin in the Holtemme River, Germany. Based on existing pre-event macroinvertebrate community data, we monitored the effects and recovery of the macroinvertebrate community for more than two years after the spill. Strong short-term effects were apparent for all taxa with the exception of Chironomidae and Tubificidae. Effects could also be observed on the community level as total abundance, taxa number and biomass strongly decreased. Total abundance and taxa number showed a fast recovery. Regarding long-term effects, the total biomass remained substantially below the pre-contamination level (76%) until the end of the study. Also the abundances of three taxa (Gammarus, Leuctra, Limnius Ad.) did not return to levels prior to the spill even after 26 months. This lack of the taxon-specific recovery was likely due to their long generation time and a low migration ability due to a restricted connectivity between the contaminated site and uncontaminated stream sections. These factors proved to be stronger predictors for the recovery than the pesticide tolerance. We revealed that the biological indicators SPEARpesticides and share of Ephemeroptera, Plecoptera and Trichoptera (EPT) are not suitable for the identification of such extreme events, when nearly all taxa are eradicated. Both indicators are functioning only when repeated stressors initiate long-term competitive replacement of sensitive by insensitive taxa. We conclude that pesticide spills can have significant long-term effects on stream macroinvertebrate communities. Regular ecological monitoring is imperative to identify such ecosystem impairments, combined with analytical chemistry methods to identify the potential sources of spills.

Transformation of short-chain chlorinated paraffins by the bacterial haloalkane dehalogenase LinB - Formation of mono- and di-hydroxylated metabolites.

Short-chain chlorinated paraffins (SCCPs) are listed as persistent organic pollutants (POPs) under the Stockholm Convention. Such substances are toxic, bioaccumulating, transported over long distances and degrade slowly in the environment. Certain bacterial strains of the Sphingomonadacea family are able to degrade POPs, such as hexachlorocyclohexanes (HCHs) and hexabromocyclododecanes (HBCDs). The haloalkane dehalogenase LinB, expressed in certain Sphingomonadacea, is able to catalyze the transformation of haloalkanes to hydroxylated compounds. Therefore, LinB is a promising candidate for conversion of SCCPs. Hence, a mixture of chlorinated tridecanes was exposed in vitro to LinB, which was obtained through heterologous expression in Escherichia coli. Liquid chromatography mass spectrometry (LC-MS) was used to analyze chlorinated tridecanes and their transformation products. A chloride-enhanced soft ionization method, which favors the formation of chloride adducts [M+Cl]- without fragmentation, was applied. Mathematical deconvolution was used to distinguish interfering mass spectra of paraffinic, mono-olefinic and di-olefinic compounds. Several mono- and di-hydroxylated products including paraffinic, mono-olefinic and di-olefinic compounds were found after LinB exposure. Mono- (rt = 5.9-6.9 min) and di-hydroxylated (rt = 3.2-4.5 min) compounds were separated from starting material (rt = 7.7-8.5 min) by reversed phase LC. Chlorination degrees of chlorinated tridecanes increased during LinB-exposure from nCl = 8.80 to 9.07, indicating a preferential transformation of lower chlorinated (Cl<9) tridecanes. Thus, LinB indeed catalyzed a dehalohydroxylation of chlorinated tridecanes, tridecenes and tridecadienes. The observed hydroxylated compounds are relevant CP transformation products whose environmental and toxicological effects should be further investigated.

Characterization of synthetic single-chain CP standard materials - Removal of interfering side products.

The photolytic chlorination of n-alkanes in presence of sulfuryl chloride (SO2Cl2) was explored to produce new standard materials. Five mixtures of chlorinated tetradecanes were synthesized with chlorination degrees (mCl,EA) varying from 43.7% to 59.4% (m/m) based on elemental analysis. Chlorine-enhanced negative chemical ionization mass spectrometry (CE-NCI-MS) forcing the formation of chloride-adduct ions [M+Cl]- was applied to characterize these materials which all contained tetra-to deca-chlorinated paraffins. Deconvolution of respective mass spectra revealed the presence of chlorinated olefins (COs). CO levels were highest in materials, which were exposed longest. All synthesized materials also contained two classes of polar impurities, tentatively assigned as sulfite- and sulfate-diesters with molecular formulas of C14H28-xO3SClx (x = 1-4) and C14H28-xO4SClx (x = 3-6), respectively. MS data were in accordance with the proposed structures but further work is needed to deduce their constitutions. These compounds are thermolabile and were not detected with GC-MS methods. We could remove these sulfur-containing impurities from the CPs with normal-phase liquid chromatography. In conclusion, single-chain CP materials were synthesized via chlorination of n-alkanes with sulfuryl chloride, but these materials contained reactive side products which should be removed to gain non-reactive and stable CP materials suitable as standards and for fate and toxicity studies.

Biotransformation of short-chain chlorinated paraffins (SCCPs) with LinA2: A HCH and HBCD converting bacterial dehydrohalogenase.

Short-chain chlorinated paraffins (SCCPs) are polyhalogenated hydrocarbons as are hexachlorocyclohexanes (HCHs) and hexabromocyclododecanes (HBCDs). They all have been classified as persistent organic pollutants (POPs) under the UN Stockholm Convention. Per se such compounds are transformed slowly in the environment, transported over long distances and accumulate in biota. Several Sphingomonadacea strains isolated from HCH dump sites have evolved to express enzymes that can transform HCHs and HBCDs. We hypothesized that LinA2, a dehydrohalogenase expressed in such bacteria, may also transform CPs to chlorinated olefins (COs). Three mixtures of penta- to deca-chlorinated undecanes (C11), dodecanes (C12) and tridecanes (C13) were exposed to LinA2. High-resolution full-scan mass spectra (R∼8'000) of CPs and COs were obtained applying a soft ionization method, enhancing chloride-adduct [M+Cl]- formation. A mathematical deconvolution procedure was used to separate interfering spectra to verify that LinA2 indeed catalyzed the conversion of CPs to COs. About 20-40% of the material was transformed in 24 h, about 50-70% was converted in 200 h. A bimodal first-order kinetic model could describe transformations of reactive and persistent CPs. Under the given conditions reactive CPs (τ1/2 = 1.4-6.9 h) were converted 30 to 190-times faster than the persistent ones (τ1/2 = 150-260 h). Proportions of persistent isomers (pp) varied from 60 to 80%. Lower chlorinated homologues contained higher proportions of persistent isomers. In conclusion, SCCP mixtures contain both, material that is readily converted by LinA2, and persistent material that is not or only slowly transformed.

Environmental Risks of Medium-Chain Chlorinated Paraffins (MCCPs): A Review.

Chlorinated paraffins are industrial chemicals that can be subdivided into short-chain (SCCP), medium-chain (MCCP), and long-chain (LCCP) chlorinated paraffins. The global production volumes of MCCPs are nowadays suspected to be much higher than those of S- and LCCPs, and the few available studies on the environmental occurrence of chlorinated paraffins report often higher MCCP concentrations than S- or LCCP concentrations in the environment. The present review focuses, therefore, on MCCPs specifically and provides a literature overview and a data analysis of the production volumes, PBT properties (persistence, bioaccumulation potential, and toxicity), and the worldwide measured concentrations of MCCP in environmental samples, biota, and humans. Furthermore, we include our own measurements of technical CP formulations from China, the major global producing country, to estimate the global production amounts of MCCPs. The key findings from this review are that (1) MCCPs are toxic to the aquatic environment, and the available data suggest that they are also persistent; (2) available time trends for MCCPs in soil, biota, and most of the sediment cores show increasing time trends over the last years to decades; and (3) MCCP concentrations in sediment close to local sources exceed toxicity thresholds (i.e., the PNEC). Our study shows that overall, MCCPs are of growing concern, and regulatory actions should be considered seriously.

Screening of Pesticide and Biocide Patterns As Risk Drivers in Sediments of Major European River Mouths: Ubiquitous or River Basin-Specific Contamination?

Pesticides and biocides (PaB) are ubiquitously present in aquatic ecosystems due to their widespread application and have been detected in rivers at concentrations that may cause distress to aquatic life. Many of these compounds accumulate in sediments acting as long-term source for aquatic ecosystems. However, data on sediment contamination with current-use PaB in Europe are scarce. Thus, in this study, we elucidated PaB patterns and associated risks in sediments of seven major European rivers focusing on their last stretch as an integrative sink of particles transported by these rivers. Sediments were extracted with pressurized liquid extraction (PLE) using a broad-spectrum method recovering many compound classes with a wide range of physicochemical properties. Altogether 126 compounds were analyzed and 81 of them were detected with LC-HRMS and GC-NCI-MS/MS at least in one of the sediments. The highest number of compounds was detected (59) in River Elbe sediments close to Cuxhaven with outstanding concentrations ranging from 0.8 to 1691 mg/g organic carbon. Multivariate analysis identified a cluster with 3 ubiquitous compounds (cyhalothrin, carbendazim, fenpropimorph) and three clusters of chemicals with higher variability within and between rivers. Risk assessment indicates an acute toxic risk to benthic crustaceans at all investigated sites with the pyrethroids tefluthrin and cyfluthrin together with the fungicide carbendazim as the main drivers. Risks to algae were driven at most sites almost exclusively by photosynthesis inhibitors with estuary-specific herbicide mixtures, while in the rivers Po and Gironde cell division inhibitors played an important role at some sites. Mixtures of specific concern have been defined and suggested for integration in future monitoring programs.

Transformation of chlorinated paraffins to olefins during metal work and thermal exposure - Deconvolution of mass spectra and kinetics.

Chlorinated paraffins (CPs) are high production volume chemicals widely used as additives in metal working fluids. Thereby, CPs are exposed to hot metal surfaces which may induce degradation processes. We hypothesized that the elimination of hydrochloric acid would transform CPs into chlorinated olefins (COs). Mass spectrometry is widely used to detect CPs, mostly in the selected ion monitoring mode (SIM) evaluating 2-3 ions at mass resolutions R < 20'000. This approach is not suited to detected COs, because their mass spectra strongly overlap with CPs. We applied a mathematical deconvolution method based on full-scan MS data to separate interfered CP/CO spectra. Metal drilling indeed induced HCl-losses. CO proportions in exposed mixtures of chlorotridecanes increased. Thermal exposure of chlorotridecanes at 160, 180, 200 and 220 °C also induced dehydrohalogenation reactions and CO proportions also increased. Deconvolution of respective mass spectra is needed to study the CP transformation kinetics without bias from CO interferences. Apparent first-order rate constants (kapp) increased up to 0.17, 0.29 and 0.46 h-1 for penta-, hexa- and heptachloro-tridecanes exposed at 220 °C. Respective half-life times (τ1/2) decreased from 4.0 to 2.4 and 1.5 h. Thus, higher chlorinated paraffins degrade faster than lower chlorinated ones. In conclusion, exposure of CPs during metal drilling and thermal treatment induced HCl losses and CO formation. It is expected that CPs and COs are co-released from such processes. Full-scan mass spectra and subsequent deconvolution of interfered signals is a promising approach to tackle the CP/CO problem, in case of insufficient mass resolution.

Deconvolution of Mass Spectral Interferences of Chlorinated Alkanes and Their Thermal Degradation Products: Chlorinated Alkenes.

Chlorinated paraffins (CPs) are high production volume chemicals and ubiquitous environmental contaminants. CPs are produced and used as complex mixtures of polychlorinated n-alkanes containing thousands of isomers, leading to demanding analytical challenges. Due to their high degree of chlorination, CPs have highly complex isotopic mass patterns that often overlap, even when applying high resolution mass spectrometry. This is further complicated in the presence of degradation products such as chlorinated alkenes (CP-enes). CP-enes are formed by dehydrochlorination of CPs and are expected thermal degradation products in some applications of CPs, for example, as metal working fluids. A mathematical method is presented that allows deconvolution of the strongly interfered measured isotope clusters into linear combinations of isotope clusters of CPs and CP-enes. The analytical method applied was direct liquid injection into an atmospheric pressure chemical ionization source, followed by quadrupole time-of-flight mass spectrometry (APCI-qTOF-MS), operated in full scan negative ion mode. The mathematical deconvolution method was successfully applied to a thermally aged polychlorinated tridecane formulation (Cl5-Cl9). Deconvolution of mass patterns allowed quantifying fractions of interfering CPs and CP-enes. After exposure to 220 °C for 2, 4, 8, and 24 h, fractions of CP-enes within the respective interfering clusters increased from 0-3% at 0 h up to 37-44% after 24 h. It was shown that thermolysis of CPs follows first-order kinetics. The presented deconvolution method allows CP degradation studies with mass resolution lower than 20000 and is therefore a good alternative when higher resolution is not available.