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Abstract The previously not studied photochemical degradation of sulfamethoxazole (SMX) to the isomer of SMX (ISO) was measured via a polychromatic (Xe) and a monochromatic (Hg) light source and accompanied by quantum chemical DFT calculations. In addition to the $$\mathrm{p}K_\mathrm{a} = \;7.0 \pm 0.1$$ p K a = 7.0 ± 0.1 of ISO, tautomer-dependent properties such as the $$K_\mathrm{OW}$$ K OW were measured and theoretically confirmed by DFT. The kinetics in solutions below and above the $$\mathrm{p}K_\mathrm{a} = 5.6$$ p K a = 5.6 of SMX were studied for the available and quantifiable products SMX, ISO, 3-amino-5-methylisoxazole (AMI), 2-amino-5-methyloxazole (AMO), and sulfanilic acid (SUA). The quantum yields of the neutral ($$\Phi _\mathrm{N}$$ Φ N ) and anionic $$\Phi _\mathrm{A}$$ Φ A ) forms of SMX ($$\Phi _\mathrm{A} = 0.03 \pm 0.001$$ Φ A = 0.03 ± 0.001 , $$\Phi _\mathrm{N} = 0.15 \pm 0.01$$ Φ N = 0.15 ± 0.01 ) and ISO ($$\Phi _\mathrm{A} = 0.05 \pm 0.01$$ Φ A = 0.05 ± 0.01 and $$\Phi _\mathrm{N} = 0.06 \pm 0.02$$ Φ N = 0.06 ± 0.02 ) were found to be wavelength-independent. In a competitive reaction to the formation of ISO from SMX, the degradation product TP271 is formed. Various proposed structures for TP271 described in the literature have been studied quantum mechanically and can be excluded for thermodynamic reasons. In real samples in a northern German surface water in summer 2021 mean concentrations of SMX were found in the range of 120 ng/L. In agreement with the pH-dependent yields, concentrations of ISO were low in the range of 8 ng/L. Graphical abstract

The vapor pressure is a specific and temperature-dependent parameter that describes the volatility of a substance and thus its driving force for evaporation or sublimation into the gas phase. Depending on the magnitude of the vapor pressure, there are different methods for experimental determination. However, these are usually associated with a corresponding amount of effort and become less accurate as the vapor pressure decreases. For purposes of vapor pressure prediction, algorithms were developed that are usually based on quantitative structure–activity relationships (QSAR). The quantum mechanical (QM) approach followed here applies an alternative, much less empirical strategy, where the change in Gibbs free energy for the transition from the condensed to the gas phase is obtained from conformer ensembles computed for each phase separately. The results of this automatic, so-called CRENSO workflow are compared with experimentally determined vapor pressures for a large set of environmentally relevant compounds. In addition, comparisons are made with the single structure-based COSMO-RS QM approach, linear-free-energy relationships (LFER) as well as results from the SPARC program. We show that our CRENSO workflow is superior to conventional prediction models and provides reliable vapor pressures for liquids and sub-cooled liquids over a wide pressure range.

Octanol/water (KOW), octanol/air (KOA), and hexadecane/air (KHdA) partition coefficients are calculated for 67 organic compounds of environmental concern using computational chemistry. The extended CRENSO workflow applied here includes the calculation of extensive conformer ensembles with semiempirical methods and refinement through density functional theory, taking into account solvation models, especially COSMO-RS, and thermostatistical contributions. This approach is particularly advantageous for describing large and nonrigid molecules. With regard to KOW and KHdA, one can refer to many experimental data from direct and indirect measurement methods, and very good matches with results from our quantum chemical workflow are evident. In the case of the KOA values, however, good matches are only obtained for the experimentally determined values. Larger systematic deviations between data computed here and available, nonexperimental quantitative structure-activity relationship literature data occur in particular for phthalic acid esters and organophosphate esters. From a critical analysis of the coefficients calculated in this work and comparison with available literature data, we conclude that the presented quantum chemical composite approach is the most powerful so far for calculating reliable partition coefficients because all physical contributions to the conformational free energy are considered and the structure ensembles for the two phases are generated independently and consistently.

Methylxanthines are commonly recommended as anthropogenic markers, yet possible diffuse sources are largely unaccounted for. In this study, eight methylxanthines and xanthine were determined jointly in an entire river system for the first time. Overall, 49 samples were taken from the River Wietze (Lower Saxony, Germany) and its tributaries in four sampling campaigns. In addition, consecutive rainwater samples as well as influent and effluent samples from the largest adjacent municipal wastewater treatment plant (WWTP) were taken. All samples were enriched using SPE and analysed via LC-MS/MS. For xanthine, the standard addition method was applied. All investigated compounds were found in concentrations ranging from some dozen to some hundred ng L−1. For isocaffeine, 7-methylxanthine, and xanthine, measured concentrations in the River Wietze are the first available concentrations in surface water. Mass loads displayed a high seasonal variability and up to 144 g day−1 of methylxanthines were discharged into the receiving river. Municipal WWTPs were found to be an important and constant point source of all compounds. However, the high dependence of mass loads on discharges in the river as well as the detection of most methylxanthines at the blank site and in rainwater samples suggest additional diffuse introduction pathways. Solely the occurrence of isocaffeine in the River Wietze was found to be exclusively attributable to municipal wastewater discharge. Therefore, while caffeine and its degradation products are unsuitable for tracking the presence of treated or untreated wastewater in fluvial systems, isocaffeine can be recommended as a marker for the discharge of treated wastewater.

The chemical background of olfactory perception has been subject of intensive research, but no available model can fully explain the sense of smell. There are also inconsistent results on the role of the isotopology of molecules. In experiments with human subjects it was found that the isotope effect is weak with acetone and D6‐acetone. In contrast, clear differences were observed in the perception of octanoic acid and D15‐octanoic acid. Furthermore, a trained sniffer dog was initially able to distinguish between these isotopologues of octanoic acid. In chromatographic measurements, the respective deuterated molecule showed weaker interaction with a non‐polar liquid phase. Quantum chemical calculations give evidence that deuterated octanoic acid binds more strongly to a model receptor than non‐deuterated. In contrast, the binding of the non‐deuterated molecule is stronger with acetone. The isotope effect is calculated in the framework of statistical mechanics. It results from a complicated interplay between various thermostatistical contributions to the non‐covalent free binding energies and it turns out to be very molecule‐specific. The vibrational terms including non‐classical zero‐point energies play about the same role as rotational/translational contributions and are larger than bond length effects for the differential isotope perception of odor for which general rules cannot be derived., The scent of deuterium: For a mechanistic understanding of the olfactory perception of molecules, it is an interesting aspect whether or not isotopological substances are perceived differently. To investigate this question, humans and a trained sniffer dog were exposed to deuterated and non‐deuterated substances. The experimental results, supplemented by quantum mechanical calculations, provide insights into the interaction of molecules with receptors.

For the first time the occurrence of 25 organic micropollutants (OMPs) including; 11 personal care products (PCPs), six phthalate ester plasticizers (PEPs) and eight organophosphorus flame retardants (OPFRs) was investigated in 72 water samples obtained from five bays in the Uganda sector of Lake Victoria. In addition, an assessment of the potential ecotoxic risk of the target OMPs to aquatic organisms was conducted. Water samples were analyzed for the target OMPs using gas chromatography coupled with mass spectrometry (GC/MS). All the target PCPs were found in all the water samples with the exception of musk ketone and 2,6-di-tert-butylphenol. Triclosan (89–1400 ng L−1), benzophenone (36–1300 ng L−1), and 4-methylbenzylidine camphor (21–1500 ng L−1) were the most predominant PCPs. All the six plasticizers were found in all the water samples with dibutyl phthalate (350-16 000 ng L−1), and bis-(2-ethylhexyl) phthalate (210–23 000 ng L−1) detected at the highest concentrations. Five OPFRs out of the eight targeted were found in all the water samples. Tricresyl phosphate (25–8100 ng L−1), tris-(2-chloroethyl) phosphate (24–6500 ng L−1) and triphenyl phosphate (54–4300 ng L−1) were the most dominant OPFRs. The highest concentrations of OMPs were recorded in Murchison and Thurston Bays, presumably due to industrial wastewater effluents from the highly industrialized localities of the two Bays. Ecotoxicological risk assessment showed that PCPs (triclosan, musk ketone, and 4-MBC), plasticizers (dibutyl phthalate, bis-(2-ethylhexyl) adipate and bis-(2-ethylhexyl) phthalate) and OPFRs (tricresyl phosphate, triphenyl phosphate and tris-(2-chloroethyl) phosphate) pose a high ecotoxic risk to lives of aquatic organisms (risk quotients, RQ > 1).

The occurrence of 24 pharmaceuticals (including; 15 antibiotics, three analgesic/anti-inflammatory drugs, three anti-epileptic/ antidepressant drugs, two beta blockers, and one lipid regulator) was investigated in 75 water samples collected from four bays in the Ugandan part of Lake Victoria. In addition, the potential environmental risk of the target pharmaceutical compounds to aquatic organisms in the aquatic ecosystem of Lake Victoria was assessed. Water samples were extracted using solid phase extraction and analyzed for pharmaceuticals using high- performance liquid chromatography coupled with triple quadrupole mass spectrometry (LC/MS/MS). Eighteen of the 24 pharmaceuticals occurred at quantifiable concentrations. Sulfamethoxazole (1-5600 ng L-1), trimethoprim (1-89 ng L-1), tetracycline (3-70 ng L-1), sulfacetamide (1-13 ng L-1), and ibuprofen (6-780 ng L-1) occurred at quantifiable concentrations in all water samples. Sulfamethazine (2-50 ng L-1), erythromycin (10-66 ng L-1), diclofenac (2-160 ng L-1), and carbamazepine (5-72 ng L-1) were only quantifiable in water samples from Murchison Bay. The highest concentrations of pharmaceuticals were found in Murchison Bay, the main recipient of sewage effluents, industrial and municipal waste from Kampala city via the Nakivubo channel. Ecotoxicological risk assessment showed that sulfamethoxazole, oxytetracycline, erythromycin, and diclofenac pose a high toxic risk to aquatic organisms in the lake, while ciprofloxacin, norfloxacin, and ibuprofen pose a medium risk. This study is the first of its kind to report the levels and ecotoxic risks of pharmaceutical compounds in Lake Victoria waters, of Uganda, and East Africa as a whole. Funding agencies: International Programme in Chemical Sciences (IPICS) under the International Science Programme (ISP), Uppsala University, Sweden [UGA 01]; German Academic Exchange Service (Deutscher Akademischer Austauschdienst, DAAD)Deutscher Akademischer Austausch Dien

Worldwide, the aquatic environment is contaminated by micro-pollutants, such as ingredients of personal care products, pesticides and pharmaceuticals. This contamination is one of the major environmental issues of global concern. Adsorption is one of approach, which has been most extensively discussed within recent years for the reduction of the input of micro-pollutants into the environment. In the present study, the natural clay classified as Na-montmorillonite, was characterized and tested for its potential to remove four model compounds representing different polarity and ionizability: i) diatrizoic acid (DAT), ii) iopamidol (IOP), iii) metformin (MTF), and iv) carbamazepine (CBZ). The adsorption efficiency of clay was evaluated by initial compound concentration, effect of pH, contact time and temperature. The results indicated that clay was able to remove the pharmaceuticals from aqueous medium with an efficiency of 70% for CBZ and MTF. In contrast, clay showed a lower removal of 30% for DAT and no removal for IOP. The results indicate that clay could rapidly and efficiently reduce the concentration of CBZ and MTF, which could provide a solution to remove some substances, without undesirable by-product generation. However, this study clearly demonstrated that removal rates strongly depend on the compound. Albeit chemical structure may play a role for the different degree of removal, this study could not completely explain the sorption mechanism between sorbent-sorbate interactions.

Permeable reactive barriers (PRBs) are alternatives to common active groundwater remediation technologies including those based on pump and treat [1-5]. PRB is a passive in situ groundwater remediation technique that avoids several inherent technical drawbacks of active systems a priori. A PRB is defined as an in situ method for remediating contaminated groundwater which combines a passive chemical or biological treatment zone with subsurface fluid flow management [6]. PRBs that were first installed in the United States in the early 1990s used zero-valent iron (e.g., elementary iron). Due to the inability of iron (Fe) to efficiently remediate polycyclic aromatic hydrocarbons (PAHs), for the past 15 years, activated carbon has been used in PRBs as an additional adsorbent for PAHs and other related organic compounds [7,8].

Dark and photolysis reactions in solution were investigated for 9-acridinecarboxaldehyde (ACL). ACL reacts in the dark at T = 20 °C and pH = 7.0 in an air saturated solution to the main product 9-acridinecarboxylic acid (ACA) and to the minor product 9-acridinemethanol (ACM) with a lifetime of τ = 4.3 days. The dissociation constant of the base ACLH+ was determined to be pKa ± σ = 4.38 ± 0.04. The photolysis of ACL was investigated using a polychromatic Xe-light source. The quantum yield in aqueous solution at T = 20 °C in a concentration range of c0(ACL) = 0.18-16.6 μM for pH > pKa and for nitrogen, air and oxygen aerated solutions was found to be Φ ± σ = (0.015 ± 0.003) mol/mol, independent from concentration. The quantum yield of ACLH+, i.e. for pH ≪ pKa, is by a factor of 2 higher (Φ = 0.029 mol/mol). Quantum yields in methanol and isopropanol are slightly lower compared to water and in acetone lower by about a factor of 20. In acetonitrile ACL was found to be practically photostable. Minimum lifetimes in sunlight for a measurement on September 5, 2017 were in the range of τ = 5-10 minutes. The diurnal photolysis of ACL in sunlight was satisfactory explained using the mean quantum yield, the absorption spectrum and photon fluxes with suitable corrections for cloudiness and the dimensions of the setup. For low concentrations ACR is formed with a yield of practically 100% in the photolysis reaction. However, with increasing concentration of ACL yields of ACR decrease and yields of ACA increase. 9(10H)-Acridinone and ACM were always detected as minor products with yields below 2%. 9-Methylacridine was never detected in any reaction of ACL. Strong indications are presented of a photolysis reaction of ACL in a river located in Lower Saxony (Germany) with a corresponding equimolar formation of ACR. ACL is therefore a direct precursor of ACR in natural surface water.

The dependence of the quantum yield of metamitron on oxygen concentration in the range cO2 = (0.005–12.6)· 10−4 M in aqueous solution was investigated with a polychromatic Xe-light source in the wavelength region 270–376 nm. The quantum yield of Φ = 0.022 ± 0.002 mol mol−1 at T = (293 ± 3) K and cO2 =2.8·10−4 M is independent from metamitron concentration in the range of cM = 8 ·10−8 − 1.8 · 10−4 M. A weak temperature dependence of the photolysis of metamitron at constant oxygen concentration was found with an activation energy of EA = (3 ± 1) kJ mol−1. The yield (ν = 0.91) of the main product desamino-metamitron does not depend on start concentration of metamitron, oxygen concentration or temperature (in the range of T = 281.5–327 K). Oxygen is necessary in the photolysis of metamitron. Quantum yields for the photoreaction of metamitron increase from practically zero at low oxygen concentrations (Φ = 0.002 mol mol−1 at cO2 −6 M) to a maximum of Φmax = 0.042 mol mol−1 at cO2 =5.1·10−5 M and declines with increasing oxygen concentration to a value of Φ = 0.006 mol mol−1 in oxygen saturated solutions. Two reaction sequences with a reaction from the triplet state T1 and from a recently proposed transient triplet state T1′ were used to explain the oxygen-dependent rate constants of metamitron. Both sequences explain the oxygen dependence equally well and it was not possible to distinguish between both mechanisms. Aqueous solutions of metamitron are recommended as a promising actinometric system, especially suitable for measurements in sunlight.

For the first time the occurrence of 26 nitrogen heterocyclic polyaromatic hydrocarbons (N-HETs) and the antiepileptic drug carbamazepine (CBZ) as a marker for anthropogenic influence was determined in an entire river system and its influents. Besides the investigation of diurnal and annual variations in concentrations, dilution and load calculations, the aims were to facilitate transferability to other rivers by identifying sources of the different substances. To create a sufficient database over 180 aqueous samples from the River Fuhse (Lower Saxony, Germany), its catchment area, effluents of municipal and industrial wastewater treatment plants (WWTPs) and rainwater were analyzed. Typical substances found in background water samples and rain samples were quinoline and isoquinoline, whereas 1-/3-methylisoquinoline were traced back to an industrial WWTP. Due to similar concentration levels in the effluents of municipal WWTPs, their impact on the river correlated with their nominal loads. In municipal WWTP effluents CBZ (cmedian=1693ngL(-1)), 2-methylquinoline (cmedian=64ngL(-1)), and acridine (cmedian=62ngL(-1)) prevailed. Although the occurrence of N-HETs at contaminated sites is a widely discussed scientific topic, this study showed that the investigated site was a source with only small volumetric contribution to N-HET concentrations in the adjacent river. In total the River Fuhse discharges 20kga(-1) N-HETs and 21kga(-1) CBZ into the receiving river.

Im Einzugsgebiet der Fuhse (Niedersachsen) wurden Klaranlagenablaufe und Oberflachengewasser auf die vasodilatierenden Substanzen Sildenafil, Tadalafil und Vardenafil untersucht. Diese Substanzen gehoren zur Stoffgruppe der Heterocyclen und sind in Potenzmitteln enthalten.

In situ measurements of air and water phases at a wastewater treatment plant (WWTP) were used to investigate the partitioning behavior of perfluorocarboxylic acids (PFCAs), perfluorosulfonic acids (PFSAs) and perfluorooctyl sulfonamide (HFOSA) and their conjugate bases (PFC -s, PFS -s, and FOSA -, respectively). Particle-dissolved (R d) and air-water (Q AW) concentration ratios were determined at different tanks of a WWTP. Sum of concentrations of C 4-12, 14 PFC(A)s, C 4,6,8,10 PFS(A)s and (H)FOSA were as high as 50pgm -3 (atmospheric gas phase), 2300ngL -1 (aqueous dissolved phase) and 2500ngL -1 (aqueous particle phase). Particle-dissolved concentration ratios of total species, log R d, ranged from -2.9 to 1.3 for PFS(A)s, from -1.9 to 1.1 for PFC(A)s and was 0.71 for (H)FOSA. These field-based values agree well with equilibrium partitioning data reported in the literature, suggesting that any in situ generation from precursors, if they are present in this system, occurs at a slower rate than the rate of approach to equilibrium. Acid Q AW were also estimated. Good agreement between the Q AW and the air-water equilibrium partition coefficient for C 8PFCA suggests that the air above the WWTP tanks is at or near equilibrium with the water. Uncertainties in these Q AW values are attributed mainly to variability in pK a values reported in the literature. The WWTP provides a unique environment for investigating environmental fate processes of the PFCAs and PFSAs under 'real' conditions in order to better understand and predict their fate in the environment.

Differences in herbivory among woody species can greatly affect the functioning of forest ecosystems, particularly in species-rich (sub)tropical regions. However, the relative importance of the different plant traits which determine herbivore damage remains unclear. Defence traits can have strong effects on herbivory, but rarely studied geographical range characteristics could complement these effects through evolutionary associations with herbivores. Herein, we use a large number of morphological, chemical, phylogenetic and biogeographical characteristics to analyse interspecific differences in herbivory on tree saplings in subtropical China. Unexpectedly, we found no significant effects of chemical defence traits. Rather, herbivory was related to the plants' leaf morphology, local abundance and climatic niche characteristics, which together explained 70% of the interspecific variation in herbivory in phylogenetic regression. Our study indicates that besides defence traits and apparency to herbivores, previously neglected measures of large-scale geographical host distribution are important factors influencing local herbivory patterns among plant species. Differences in herbivory among woody species can greatly affect the functioning of forest ecosystems, particularly in species-rich (sub)tropical regions. However, the relative importance of the different plant traits which determine herbivore damage remains unclear. Defence traits can have strong effects on herbivory, but rarely studied geographical range characteristics could complement these effects through evolutionary associations with herbivores. Herein, we use a large number of morphological, chemical, phylogenetic and biogeographical characteristics to analyse interspecific differences in herbivory on tree saplings in subtropical China. Unexpectedly, we found no significant effects of chemical defence traits. Rather, herbivory was related to the plants' leaf morphology, local abundance and climatic niche characteristics, which together explained 70% of the interspecific variation in herbivory in phylogenetic regression. Our study indicates that besides defence traits and apparency to herbivores, previously neglected measures of large-scale geographical host distribution are important factors influencing local herbivory patterns among plant species.

Polycyclic aromatic hydrocarbons (PAHs), heterocyclic PAHs (NSO-HETs), alkylated PAHs and phenols are known as the prevailing contaminants in groundwater at tar contaminated sites. Besides these local sources, the concentrations and the distribution in particular of NSO-HETs in environmental samples, such as rivers, have received notably less attention. To investigate their occurrence in river basins two sensitive analytical methods for the simultaneous extraction of 86 substances including NSO-HETs, classical EPA-PAHs, alkylated PAHs and phenols were developed: liquid-liquid extraction for the whole water phase and solid phase extraction for the dissolved water phase only. Solely GC-MS or additionally LC-MSMS for fractionated basic nitrogen heterocycles (N-HETs) were used for quantification. Limits of quantification were in the low ngL-1 range. Concentrations were determined in 29 aqueous samples from 8 relatively large rivers located in Lower Saxony (Germany) and the North Sea. NSO-HETs had comparable or even higher sum concentrations than EPA-PAHs. N-HETs, especially acridine and quinolines with concentrations of up to 20ngL-1 per substance, were predominant.

Der Versuch einer Unterteilung der Erde in einzelne Spharen in Form einer Aufteilung, d. h. Kompartimentierung in verschiedene, abgegrenzte Bereiche, ist einerseits sinnvoll aufgrund unterschiedlicher Zeitspannen und z. B. typischer Reaktionen, andererseits ist sie aufgrund der Wechselwirkungen zwischen den Kompartimenten fur eine ganzheitliche und damit nachhaltige Beschreibung der Prozesse auf der Erde hinderlich. Die heutige Sichtweise der vielfaltigen Prozesse auf der Erde nimmt darauf direkten Bezug. Dies zeigt sich im Besonderen auch in der Beschreibung klimatischer Vorgange, die im Rahmen des Klimasystems die Wechselwirkungen aller globalen Spharen umfasst. In diesem Kapitel werden speziell einige Aspekte der Atmosphare und der Lithosphare dargestellt und diskutiert.

The reactivity of both isomers (Z and E) of pyrifenox (2′,4′-dichloro-2-(3-pyridyl)acetophenone (E,Z)O-methyloxime), adsorbed on quartz-aerosol as an inert carrier, against OH radicals from the gas-phase was investigated in a smog chamber (2400 l) at T=299 K and 50% rel. humidity. OH-radicals were produced in the dark using hydrazine/ozone and peroxynitric acid/NO and by photolysis using methyl nitrite, hydrogen peroxide, ozone and nitrogen dioxide as OH-precursors. OH-radical concentrations (< 105 < [OH]/cm−3 < 8 · 106) were determined from the simultaneous consumption of up to 6 reference compounds with well-known OH-rate constants. Using methyl nitrite, nitrogen dioxide and peroxynitric acid as OH-precursors the OH-rate constant at T=299 K for pyrifenox was found to be identical for both isomers: (kOH ± σ) = (1.8 ± 0.4)·10−11cm3·s−1 leading to half-lives of pyrifenox in the atmosphere of t12 = (0.45 – 0.9) days at typical mean, tropospheric OH-radical concentrations in the range of [OH] = (5 – 10) · 105 cm−3. Side reactions of HO2 or other radicals perturbed the degradation behaviour of pyrifenox in the presence of hydrazine/ozone and hydrogen peroxide and ozone under irradiation and were separated from OH. The rate constants for the reaction with gaseous hydrogen peroxide and ozone were determined, found to be low and negligible with respect to the degradation of pyrifenox in the environment: (kO3 ± σ) = (2 ± 1) · 10−19 cm3 s−1 and (kH2O2 ± σ) = (8 ± 8) · 10−20 cm3 s−1. Besides the reaction with OH-radicals a photo- isomerization Z ⇌ E was found. Within the error of experiments no irreversible loss of pyrifenox due to photolysis was found. A ketone (after reaction of OH at the CH2-group in pyrifenox) was tentatively assigned as the only product found.

This paper presents the investigation of the photochemical reaction of chlorotoluron (3-(3-chloro-4-methyl-phenyl)-1,1-dimethylurea) in CH 3 CN, hexane, and aqueous and buffered solutions (pH = 4, 7, and 9) and of isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) in aqueous and buffered solutions using a polychromatic light source at a temperature of 22°C. For chlorotoluron, isosbestic points were found (with the exception of hexane as solvent) and ultraviolet spectroscopy was used to obtain kinetic data. The main photoproduct for the photolysis of chlorotoluron in aqueous solutions was identified as 3-(3-hydroxy-4-methyl-phenyl)-1,1 dimethylurea. Quantum yields found in aqueous and buffered solutions were comparable (about 0.07) and 2 times lower and 10 times higher in CH 3 CN and hexane, respectively. No isosbestic points were found for isoproturon, and quantum yields of about 0.004 were calculated in all solutions. Chlorotoluron and isoproturon present very low molar extinction coefficients above 290 nm, and they can be assumed to be photostable with respect to direct irradiation by sunlight.

The reaction of terbuthylazine (TBA) with OH radicals was investigated in an aerosol smog chamber (2400 L). TBA was adsorbed well below a monolayer on silicon dioxide as inert carrier. OH radicals were produced from hydrogen peroxide, ozone, and nitrogen dioxide. The OH concentrations span a region of 105 ≤ cOH/cm-3 ≤ 107 and were monitored by the consumption of butane, 2,2-dimethylbutane, pentafluorobenzene, 2,2,4,4-tetramethylbutane, and toluene as reference compounds. The OH rate constant of TBA obtained from nine smog chamber runs at T = 300 K on the aerosol is kOH(TBA) = (1.1 ± 0.2) × 10-11 cm3 s-1. Beside the OH reaction, a loss path not initiated by OH radicals was found (k = (1.9 ± 0.5) × 10-5 s-1), which can be explained only in part by loss processes observed in the dark. Using the OH rate constant determined on the aerosol as an estimate for the corresponding OH reaction in the environment, a half-life of about 1 day (with OH concentrations of 5−10 × 105 cm-3) is obtained. Using the UV spectrum...

Photochemical reactions of atrazine, propazine, simazine, terbuthylazine, ametryn and atraton were investigated in aqueous and buffered (pH=7–9) solutions (containing a few percent of acetonitrile) using a polychromatic Xe light source at T=22[ddot]C. For terbuthylazine the photochemistry is investigated in detail, including solvent-, temperature-and pH-dependence and products found. The role of polychromatic light sources used in investigations of the photochemistry of triazines is discussed. For the first time, quantum yield measurements were performed in the UV-band between 240–300 nm of the chlorotriazines and ametryn. Isosbestic points were found in the UV-spectra at different irradiation times, and UV-spectroscopy was used to obtain kinetic information. Quantum yields in aqueous solutions at T=22[ddot]C for the chlorotriazines (Φ=0.048–0.062) and for ametryn (Φ=0.043) are comparable. The temperature dependence of the photoreaction of terbuthylazine leads to an activation energy of about 13 ...

Environmental contextPolyfluoroalkyl compounds, widely used chemicals in consumer and industrial products, are global pollutants in the environment. Transport mechanisms and environmental pathways of these compounds, however, are not yet fully understood. We show that a wastewater treatment plant can be an important source for polyfluoroalkyl compounds to the atmosphere where they have the potential to be transported long distances. AbstractAn air sampling campaign was conducted at a wastewater treatment plant (WWTP) to investigate air concentrations and particle–gas partitioning of polyfluoroalkyl compounds (PFCs). Samples were collected at an aeration tank and a secondary clarifier using both active high volume samplers and passive samplers comprising sorbent-impregnated polyurethane foam (SIP) disks. Water to air transport of PFCs was believed to be enhanced at the aeration tank owing to aerosol-mediated transport caused by surface turbulence induced by aeration. Mean air concentrations of target PFCs at the aeration tank were enriched relative to the secondary clarifier by factors of ~19, ~4 and ~3 for ∑fluorotelomer alcohols (FTOHs) (11 000 v. 590 pg m–3), ∑perfluorooctane sulfonamides & perfluorooctane sulfonamidoethanols (FOSAs & FOSEs) (120 v. 30 pg m–3) and ∑perfluoroalkyl carboxylates & perfluoroalkyl sulfonates (PFCAs & PFSAs) (4000 v. 1300 pg m–3) respectively. The particle associated fraction in the atmosphere increased with increasing chain length for PFCAs (from 60 to 100%) and PFSAs were predominantly bound to particles (~98%). Lower fractions on particles were found for FTOHs (~3%), FOSAs (~30%) and FOSEs (~40%). The comparison of the active and passive air sampling showed good agreement.

Comparability of sediment analyses for semivolatile organic substances is still low. Neither screening of the sediments nor organic-carbon based normalization is sufficient to obtain comparable results. We are showing the interdependency of grain-size effects with inside-sediment organic-matter distribution for PAH, PCB and organochlorine compounds. Surface sediment samples collected by Van-Veen grab were sieved and analyzed for 16 PAH, 6 PCB and 18 organochlorine pesticides (OCP) as well as organic-matter content. Since bulk concentrations are influenced by grain-size effects themselves, we used a novel normalization method based on the sum of concentrations in the separate grain-size fractions of the sediments. By calculating relative normalized concentrations, it was possible to clearly show underlying mechanisms throughout a heterogeneous set of samples. Furthermore, we were able to show that, for comparability, screening at

Four tar-contaminated sites in Germany (Lunen, Castrop Rauxel, Stuttgart and Wulknitz) were investigated and 42 polycyclic aromatic compounds (PAC) were detected in significant concentration ranges including polycyclic aromatic hydrocarbons (PAH), substituted PAC, heterocyclic PAC containing nitrogen, sulphur and oxygen as well as their metabolites. A similar composition and pattern of PAH heterocyclic PAC and metabolites were found in corresponding groundwater samples. Identification and quantification were performed using liquid-liquid extraction and analyses with gas chromatography - electron impact - mass spectrometry. Detailed investigation (in Castrop Rauxel, Germany) showed that the distribution of non-polar compounds can only be detected close to the source of contamination, whereas the distribution of more polar compounds and degradation products is more widespread downstream of an aquifer.

Photolytic degradation reactions in aqueous solution of the fungicide triphenyltin hydroxide (TPT), a compound with typical physicochemical properties of a persistent organic pollutant (POP) were investigated. The quantum yield is found to be close to unity, TPT,254±2=1.25±0.26 at 254 nm (T=295298 K). Using nitrobenzene as reference compound the OH-rate constant of TPT was found to be kOH,TPT±2=(9.4±3)×109 M-1 s-1 at T=295 K. Although the quantum yield of TPT is among the highest values found for a pesticide, the degradation by sunlight is negligible due to a lack of overlap with the UV-spectrum of TPT... Photolytic degradation reactions in aqueous solution of the fungicide triphenyltin hydroxide (TPT), a compound with typical physicochemical properties of a persistent organic pollutant (POP) were investigated. The quantum yield is found to be close to unity, TPT,254±2=1.25±0.26 at 254 nm (T=295298 K). Using nitrobenzene as reference compound the OH-rate constant of TPT was found to be kOH,TPT±2=(9.4±3)×109 M-1 s-1 at T=295 K. Although the quantum yield of TPT is among the highest values found for a pesticide, the degradation by sunlight is negligible due to a lack of overlap with the UV-spectrum of TPT...

Kinetics and product distribution of the reaction of dimethylsulfoxide (DMSO) and methanesulfinate (MSI -) with OH radicals and H 2O 2 in the aqueous phase are reported in this work. DMSO is found to be very stable in pure water or in solutions containing H 2O 2. On the other hand, it reacts very rapidly (k=4.5×10 9M -1s -1) with OH radicals. MSI - has been identified as the main intermediate product, while methanesulfonate (MS -) and sulfate were the final products due to the very fast reaction of MSI - with OH radicals (k=1.2×10 10M -1s -1). MS - has been identified as the major end product (yield higher than 95%) of both DMSO and MSI - reactions by OH radicals in aqueous solutions. The potential implications of these reactions for the biogenic sulfur cycle in the atmosphere are presented and discussed.

This paper presents first experiments of laboratory investigations of the photodegradation by direct photolysis (λ>290 nm) of cholorotahlonil, dichlobenil, chloroxynil, bromoxynil, and ioxynil in aqueous, pH-buffered, and organic solutions and the calculation of the quantum yields. The photolysis of chlorothalonil in water is low, with a corresponding low quantum yield (Φ=0.0001). Dichlobenil is photostable under the laboratory conditions used. The photoreactivity of bromoxynil and ioxynil was found to be comparable in aqueous solutions and about three times lower with respect to chloroxynil. The quantum yields obtained in water of chloroxynil, bromoxynil, and ioxynil are Φ=0.0060, 0.0093, and 0.0024, respectively. Half-lives of the pesticides in the environment with respect to direct irradiation are estimated using UV spectra and quantum yields as input variables obtained in the laboratory.

Preliminary results of a new method to investigate the OH radical reactivity of semi-volatile organic compounds (e.g., pesticides) are presented. Terbuthylazine, simazine, sodium benzoate, and bromoxynil were adsorbed on highly disperse silicon dioxide powder as an unreactive carrier at a thickness well below one monolayer. The coated material was suspended in air as an aerosol, sampled on filters, and exposed in an 840-liter Duran chamber to OH radicals, produced by photolysis of hydrogen peroxide in the gas phase. Sunlamps on top of the chamber were used as cold light sources [T(aerosol) approximately 25 degreesC]. OH radical concentrations (10(5)cOH (cm-3)3x10(6)) were monitored in the gas phase using a set of four hydrocarbons with well-known OH reactivities as reference compounds. The triazine terbuthylazine (kOH=1.1x10(-11) cm3 s-1) was used as a reference compound in the filter samples. Simazine and isoproturon were found to react with a comparable OH rate constant with respect to terbuthylazine. Sodium benzoate reacts about a factor of 3 slower. Rapid degradation was observed for bromoxynil, explained mainly by photolysis. Besides the characterization and discussion of the experimental setup used, the rate constants obtained are discussed and compared with estimated values.

Photochemical reactions of metamitron (a 4-amino substituted as-triazin-5(4H)-one) were investigated including UV- and phosphorescence spectroscopy, determination of quantum yields, comparison with measurements in sunlight and products found. The photolysis of metamitron is found to be strongly dependent on solvent and oxygen, as known for other 4-amino-triazin-5(4H)-ones. No photoreaction was found in methanol, acetonitrile and hexane. Photolysis rate constants were obtained using a xenon light source by analysis of the UV-spectra and HPLC. Quantum yields found in water and at pH=4 and 9 are comparable (σ = 0.014-0.018) and at pH=7 about a factor of 2 higher, probably influenced by the phosphate buffer used. Photochemical mechanisms are discussed. With the strong indication of a highly probable pH-independent quantum yield found, the involvement of hydroperoxyl radicals in the first step of the photoreaction, discussed before, is assumed to be unlikely. Besides desamino metamitron a second, minor (and by GC/MS and UV-spectra tentatively assigned) ring cleavage product was found.

0045-6535/$ see front matter 2013 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.chemosphere.2013.05.008 ⇑ Corresponding author. Address: Federal Environment Agency (UBA), Worlitzer Platz 1, Dessau-Roslau, Germany. Tel.: +49 34021036620; fax: +49 34021046620. E-mail address: Lena.Vierke@uba.de (L. Vierke). 1 Present address: Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment, Lennart Hjelms vag 9, 750 07 Uppsala, Sweden. Lena Vierke a,b,⇑, Lutz Ahrens , Mahiba Shoeib , Wolf-Ulrich Palm , Eva M. Webster , David A. Ellis , Ralf Ebinghaus , Tom Harner c