Despite its widespread usage in agriculture, the environmental fate of 3,4-dimethylpyrazole (DMP), the active part of the nitrification inhibitor DMPP, is relatively little investigated, especially with regards to the risk of leaching. We therefore used a combination of batch, column and lab studies to determine the fate of DMP and its degradation product 3-methylpyrazole-4-carboxylic acid (3-MPA) on sandy soils at conditions representative for a temperate climate such as that found in Northern Europe. DMP was degraded fastest in non-sterilized topsoil and slowest in sterilized subsoil. Manure increased degradation rates, but the degradation leveled off over time, leaving at least 5% after 5-12 months in both lab and field experiments. At environmentally realistic concentrations, DMP showed a relatively high sorption to topsoil, which increased by aging. Sorption cannot, however, be expected to retard the leaching of DMP much once it has reached the subsoil where degradation was also slow. The leaching potential was confirmed by the detection of low concentrations of DMP in column leachates and in pore water just above the groundwater table in the field, nonetheless, most of the non-degraded DMP remained in the upper 10 cm. The degradation product 3-MPA was quickly formed after application of DMPP, but leached in very low amounts, probably due to degradation in the topsoil. All in all, leaching of DMP and its transformation product 3-MPA seems to be low in sandy arable soil with plug flow conditions, while additional studies in other soil types are needed to evaluate if DMP can leach in soils where for example preferential flow conditions are more prevailing.

Triazole fungicides are widely detected in agricultural soils, yet their long-term persistence remains poorly understood. We evaluated how sorption, bioaccessibility, and degradation change with aging under field conditions. Topsoil was collected over 2 years from four Danish fields with detailed spray records. Tebuconazole, propiconazole, and epoxiconazole were detected 4-19 years after the last spray application, often at nearly constant concentrations. For these aged compounds, soil-water distribution coefficients could not be determined because sorption was too strong. Instead, bioaccessible fractions were quantified using hydroxypropyl-beta-cyclodextrin. Aged triazole fungicides consistently exhibited low bioaccessibility and very slow degradation. In contrast, freshly applied metconazole and prothioconazole-desthio declined rapidly and followed double first-order in parallel kinetics. Metconazole initially showed low sorption and high bioaccessibility but became increasingly inaccessible over the following year. As a result, total concentrations stabilized at a low plateau rather than approaching zero. These results demonstrate that aging reduces bioaccessibility and explains the persistence of triazole fungicides in topsoil. A fraction of applied triazole fungicides may therefore accumulate after repeated use, with implications for long-term soil quality and pesticide risk assessment.

Reversed-phase liquid chromatography coupled to high-resolution mass spectrometry (RP-LC-HRMS) is the standard for nontarget screening (NTS) of environmental samples but lacks retention of highly polar contaminants. We compared 12 chromatographic methods across four platforms, RP-LC, anion chromatography (IC), supercritical fluid chromatography (SFC), and hydrophilic interaction chromatography (HILIC), using 127 environmentally relevant compounds (logDpH7.4 -5.6 to 6.6). Compounds were analyzed in solvent and for a polar subset, in groundwater enriched by vacuum evaporation. Data were collected across four laboratories using 5 RP-LC-, 3 HILIC-, 2 SFC-, and 2 IC-HRMS setups. Feature detection with standard tools yielded more false negatives for SFC and IC. To enable a fair and method-agnostic comparison, an extracted ion chromatogram (EIC)-based workflow was used. Of the 127 compounds, 125 were detected by at least one platform. For logDpH7.4 > 0, RP-LC covered ∼90%, followed by SFC (∼70%), while IC and HILIC each covered <30%. For very polar compounds (logDpH7.4 < 0), coverage dropped across all platforms. SFC and HILIC detected up to 60% of polar analytes; IC performed better in negative ionization mode, consistent with anion-exchange separation. Detection frequency declined with polarity, reflecting analytical limitations. Combining RP-LC with either SFC or HILIC increased coverage to 94%. In spiked groundwater, coverage was lower (73%) due to matrix effects and losses during vacuum enrichment. Peak widths were narrowest for SFC (∼2.5 s) and RP-LC (∼4 s) and broadest for HILIC (∼7 s) and IC (∼17 s). Retention times showed limited cross-platform correlation while ionization efficiency was consistent, except for SFC. As no single method provided full coverage, combining RP-LC with one complementary platform (SFC, HILIC, or IC) is required to extend chemical space in environmental NTS.

To investigate the formation and leaching potential of degradation products N,N-dimethylsulfamide (DMS) and dimethylsulfamic acid (DMSA) from cyazofamid under real-world agricultural conditions, the fungicide cyazofamid was applied in a potato crop as part of the Danish Pesticide Leaching Assessment Programme (PLAP). Leaching of DMS, DMSA, 4-chloro-5-(4-methylphenyl)-1H-imidazole-2-carbonitrile (CCIM), and 4-chloro-5-(4methylphenyl)-1H-imidazole-2-carboxylicacid (CTCA) was monitored in water from the variably saturated zone (suction cups) and groundwater for more than two years following the applications. In total, 424 samples were analyzed for the content of the four degradation products. An additional laboratory study was executed in parallel with the field monitoring study. Here, cyazofamid was applied to soil columns and leaching of the four degradation products was studied under controlled conditions. In the EFSA conclusion on cyazofamid, CCIM and CTCA are mentioned as major relevant metabolites; DMS is not mentioned in the risk assessment and DMSA is only included in acute oral toxicity studies and an in vitro bacterial mutation assay. In contrast to the EFSA conclusion on cyazofamid, our studies showed no leaching of the two major metabolites, CTCA and CCIM, but instead, major leaching of DMS and DMSA in both the field and laboratory studies was observed. That is, both DMS and DMSA leached to the groundwater in concentrations >0.1 mu g/L for more than half a year. Based on this, we suggest improvements to the current pesticide risk assessment.

Urban pollution from biocides used in building materials has raised emerging concern within recent years. The evidence that the use of biocides can pollute urban groundwaters is very limited, but in Denmark, the common degradation product from the two fungicides tolylfluanid and dichlofluanid, N,N-DMS, is particularly abundant in groundwater within urban areas, which suggests an urban source in addition to its well-known agricultural sources. In addition, another widespread groundwater pollutant, 1,2,4-triazole, may originate from the fungicides propiconazole and tebuconazole, that are also used in outdoor paint and wood protection products. To study the potential pollution of groundwater from fungicides used in outdoor paint and wood protection products, we surveyed concentrations in groundwater in two urban areas, we tested leaching from facades and soil concentrations close to facades and fences, and in lab-experiments, we determined the fate of N,N-DMS and 1,2,4-triazole under different redox conditions in soil sampled down to 7 m below surface.Shallow urban groundwater contained up to 1 mu g/L N,N-DMS with concentrations of 0.1-0.3 mu g/L below a typical Danish residential area. Despite a phase-out of tolylfluanid and dichlofluanid in paint in 2015, both compounds still wash-off wooden facades and fences and was detected in soil next to the treated wood. Much higher soil concentrations, however, were found for propiconazole and tebuconazole and their common degradation product 1,2,4-triazole, reflecting the fact that they are still in use in outdoor paint and wood protection products. 1,2,4-Triazole also leached to groundwater, but concentrations decreased sharply with depth, probably due to degradation that occurred at all tested soil depths and redox conditions. N,N-DMS, on the other hand, was not degraded in deeper soil layers or under anoxic conditions. Consequently, N,N-DMS may persist in groundwater below populated areas well into the future.

Soil microbial growth and activity are generally assumed to recover rapidly after dissipation of organic toxicants. We studied the effects of four readily degradable isothiazolinone biocides (benzisothiazolinone, BIT; methylisothiazolinone, MIT; octylisothiazolinone, OIT; 4,5-dichloro-2-octyl-isothiazolinone, DCOIT) on bacterial growth, fungal growth, basal respiration, and substrate-induced respiration in controlled soil microcosm experiments. Bacterial growth followed by fungal growth were the two most sensitive endpoints during the first two days. Significant dissipation of biocides occurred within just 8 h and 94-100% had dissipated after 40 days except for DCOIT tested at a high concentration (50 mg kg-1, 54% remaining after 40 d). Despite biocide dissipation, all isothiazolinones inhibited bacterial growth for >7 days, whereas fungal growth and substrateinduced respiration were inhibited for up to 40 days. Bacterial growth recovery after 40 days was linked to development of bacterial community tolerance for DCOIT, but not for the other less persistent isothiazolinones. Our study is the first to report on toxic effects of isothiazolinones on soil microbial growth and demonstrates that inhibitory effects of isothiazolinones on soil microbial growth and activity (especially fungal growth and substrate-induced respiration) persisted even long after biocide dissipation, indicating "legacy effects" and retarded recovery of soil microbial functions. We propose that retarded recovery of fungal, relative to bacterial, growth may be a general phenomenon during the dissipation of toxicants in contaminated soils and that it may be explained by intrinsic differences between bacterial and fungal biology in soil and by competitive interactions between these two dominant groups of soil microbial decomposers.

Seed dressing with fungicide or insecticide is a standard procedure for growing major crops, but very little is known about the leaching risk and the general fate of pesticides from coated seeds. Triazole fungicides are commonly used seed dressing fungicides and recently, there has been increasing concern that 1,2,4-triazole, a major degradation product of several triazole fungicides, may leach to groundwater in concentrations exceeding the 0.1 μg/L threshold limit of the European Union. We therefore carried out a laboratory column experiment with commercial barley seeds coated with the triazole fungicides tebuconazole and prothioconazole to study the fate of the fungicides and their degradation products, especially 1,2,4-triazole. Our experiment showed that the fungicides themselves were relatively immobile in the soil columns, but also that leaching of 1,2,4-triazole will occur no matter if tebuconazole or prothioconazole is used as seed dressing. Relatively high 1,2,4-triazole concentrations (up to 0.8 μg/L) were measured in the column leachates, but when the experiment was terminated after 63 days, a total of only 1 % of the fungicides was recovered as 1,2,4-triazole in the leachate. Our results suggest that seed dressing pesticides should be considered together with spray applications when estimating the total 1,2,4-triazole load from agriculture and that seed dressing pesticides and their degradation products should be included when evaluating leaching risks from pesticide applications in agriculture.

Aquaporin-based forward osmosis (AQP FO) membranes were applied both in laboratory- and pilot-scale for removing micropollutants from water. The effect of operating parameters (feed flow, draw flow, and transmembrane pressure) on the i) rejection of micropollutants, ii) water flux, iii) reverse salt flux, and iv) water recovery of the AQP FO membrane modules was studied. Among the 21 micropollutants spiked, only four compounds, atenolol, propranolol, metoprolol, and citalopram, permeated through the AQP FO membranes to an extent that they could be quantified in the draw solutions of both the laboratory and pilot systems. The rejection rates, based on the full mass balance calculations, were between 96.1% and 99.7%, and all the other 17 compounds showed rejection exceeding 90% on both systems. The pilot AQP FO system was further employed for six days to treat effluent from a membrane bioreactor (MBR) treating municipal wastewater. 35 micropollutants were investigated. 27 of these were identified and quantified in the MBR effluent. Minute fractions of gabapentin, benzotriazole, and metoprolol were detected passing through the AQP FO membranes into the draw side with a constant rejection of around 99.2%, 95.4%, and 99.9%. Almost all other micropollutants' minimum rejection rates exceeded 80%.

The environmental fate for some selected antifouling biocides, dichlofluanid, tolylfluanid, tralopyril, and medetomidine, is relatively poorly understood with nearly all data derived from the assessment reports. Water/sediment systems and biofilms were used to determine biodegradation of the antifouling biocides. Dichlofluanid and tolylfluanid are known to hydrolyze to form DMSA (N,N-dimethyl-N'-phenylsulfamide) and DMST (N,NDimethyl-N'-(4- methylphenyl)sulfamide), respectively. DMSA did not show biodegradation, but it was shown to transform abiotically into N,N-dimethylsulfamide (N,N-DMS). In contrast, the structurally similar DMST did show biodegradation with a half-life of 5.78 days. The resulting transformation product of the biodegradation of DMST is also N,N-DMS. N,N-DMS accounted for the majority of the mass balance after 27 days in the water/sediment systems. Moreover, the biofilm systems also degraded both DMSA and DMST to N,N-DMS. The hydrolysis product of tralopyril, called BCCPCA (3-bromo-5-(4-chlorophenyl)-4-cyano-1 H-pyrrole-3-carboxylic acid), was not metabolized in the experiments and remained persistent. For this compound, a new log Kow of 2.47 was determined since the previously reported Kow value seemed to overestimate sediment partitioning. Medetomidine was removed from the water/sediment system, though, not significantly more than the control. However, a transformation product (medetomidine-acid) was detected in the incubation but not in the control, pointing to limited biodegradation. These results show that tolylfluanid can be rapidly removed by biodegradation in the marine environment, while dichlofluanid, tralopyril, and medetomidine remained in the system for a longer period of time. The prolonged stability of these biocides could mean that there is potential for accumulation in the environment. This potential is also there for the DMSA (dichlofluanid) and DMST (tolylfluanid) derived transformation product N,N-DMS, which was recalcitrant.

Little is known about the impacts of persistent triazine herbicides and biocides on soil microorganisms. Terbutryn toxicity in soil microorganisms was studied using bacterial and fungal growth, substrate induced respiration (SIR) and basal respiration as ecotoxicological end-points. In the short-term (0-7 days), increasing concentrations of terbutryn (0-800 mg kg(-1)) progressively inhibited bacterial and fungal growth by up to 33-36% (4 h) and 49-55% (7 days), whereas SIR and basal soil respiration remained unaffected. Following long-term (40 days) exposure to terbutryn, both bacterial and fungal growth were inhibited by up to 76-78%, and SIR was inhibited by up to 53%. Hence, our results unexpectedly demonstrate time-cumulative microbial growth inhibition over extended time periods in soil and indicate that current ecotoxicological guidelines may underestimate risks posed by chemicals to soil microorganisms.

Rationale In recent environmental research, multi-methods using high-performance liquid chromatography-mass spectrometry (HPLC/MS/MS) have become more and more important for the analysis of organic micropollutants in environmental matrices. As the targeted compounds usually have different physicochemical properties, the optimization of these methods is challenging. Methods The pH in the electrospray of the mass spectrometer ion source was modified independently of the one used for the HPLC separation, using a post-column HPLC flow to make the spray acidic or alkaline. The method development was carried out manually in a systematic multistep way. Results The method used for the analysis of organic biocides (e.g., terbutryn, propiconazole, and isothiazolinones) was optimized. It was shown that the use of a neutral as well as an acidified gradient could not be optimized for all target compounds, whereas a neutral gradient with post-column acidification was optimum for all target compounds. Conclusions Acidic or alkaline post-column infusion allows pH optimization for ionization conditions, independent of the pH optimization for chromatographic separation. The introduction of an additional modifier might also allow the minimization of matrix effects or directed formation of sodium adducts, without affecting the chromatographic separation.

Medetomidine has been authorized in ship hull paints as an antifouling biocide under the biocidal product regulation in Europe since 2016. Its release into marine systems causes concerns over persistence and toxicity. However, the environmental fate of medetomidine has not been fully investigated. In this study, the photodegradation of medetomidine under natural sunlight conditions was investigated using collected coastal and sea waters. In addition, the phototransformation of medetomidine with reactive species (i.e., singlet oxygen, excited triplet state organic matter, and hydroxyl radicals) under UVA light was examined. Photoproducts were isolated by high-performance liquid chromatography (HPLC), identified by a combination of nuclear magnetic resonance (NMR) spectroscopy and time-of-flight mass spectrometry (qTOF), and reaction mechanisms were proposed. The results show that medetomidine is a neutral base (pKa of protonated form = 7.2) that leads to two different protonation states in the aquatic environment. Photodegradation of neutral medetomidine was dominated by reaction with singlet oxygen, while protonated medetomidine was relatively photostable. The contribution of reactive species to the overall photodegradation of neutral medetomidine was calculated to provide an assessment of phototransformation of medetomidine. The half-live of medetomidine was < 1.5 days in natural waters (pHcoastal = 8.3; pHsea = 8.1) under sunlit near-surface conditions, suggesting that it is not persistent in the aquatic environment. Because medetomidine has a relatively short half-life in sunlit aquatic ecosystems, a number of products, such as 2-(2,3-dimethylphenyl)propanamide, can be formed by photochemical reactions of medetomidine, with unknown consequences for marine and coastal waters.

Small polar organic pollutants have been discovered to be great threats to the groundwater‚ as they often are highly mobile and persistent in the environment. 1,2,4-Triazole and N,N-dimethylsulfamide, two well-known examples of small polar compounds, are frequent pollutants of upper groundwater. Both are degradation products of several fungicides commonly or previously used in agriculture‚ but also in wood-preserving paints. A common trait in the analysis of these small polar compounds is the lack of sufficient pre-concentration methods to lower the limit of detection and enable quantitative analysis at nano-scale concentrations. To date, they are analyzed only by direct injection in HPLC-MS/MS, with detection limits just below the European threshold value for pesticides in groundwater of 0.1 μg/L. Based on a comprehensive method development, a solid phase extraction method was developed. As known LC methods for analysis of 1,2,4-triazole are based on Thermo Fisher’s Hypercarb column, emphasis was placed on testing various carbon-based materials. The final, thoroughly validated extraction protocol is based on Supelco’s ENVI-Carb Plus cartridges. With extraction recoveries close to 100% for 1,2,4-triazole and N,N-dimethylsulfamide and quantification limits of around 0.003 μg/L, the method enables extraction and quantification of polar pollutants at nano-scale concentration from groundwater samples. In addition, the method is very promising to be used for other small polar pollutants.

Antifouling biocides are known to leach out of paints and into the aquatic environment. There is currently a data gap on the occurrence of the current antifouling biocides, as legislative changes caused a change in the antifouling market. Therefore, a comprehensive monitoring study was performed across 13 Danish marinas, both waters and sediments were analyzed, including a transect and a study with seasonal resolution. Three biocides, i.e., Medetomidine, Tralopyril, and DCOIT were not detected in any of the samples. More commonly found, in 11 of the 13 marinas, were the hydrolysis products of Dichlofluanid (DMSA) and Tolylfluanid (DMST). These biocides rapidly dropped in concentration and reached background levels around 200 m from the source. The antifouling biocide Irgarol 1051 was found in all sediment samples and half of all water samples. The concentrations of Irgarol were lower than previously monitored. The decrease can likely be attributed to legislative changes and its disapproval for use since 2016.

Diflufenican is used in both agricultural and urban areas to control weeds. However, in Europe pesticides are regulated using agricultural soil data only. Urban soils where the top layer is replaced by gravel (e.g. driveways, outdoor tiled areas) can evidently differ from agricultural soils in many biotic and physical properties. In the present study, we compared the degradation, mineralization, sorption and aging of diflufenican between an agricultural sandy soil to a gravel used in urban areas. Both diflufenican and its two main aerobic metabolites were investigated. Diflufenican and the metabolites degraded slower in gravel than in agricultural soil. One of the metabolites, 2-[3-(Trifluoromethyl)phenoxy]nicotinic acid (AE B107137 as identified by EFSA; further abbreviated as AE-B), was formed from the incubation of diflufenican in both soil and gravel, however, showing different formation patterns in the two materials: No accumulation of AE-B was determined in the soil, whereas in gravel, an accumulation of AE-B was determined over the full study period of 150 days. After 150 days, approximately 10% of the applied diflufenican was mineralised in the soil (cumulative), while it was not mineralised in the gravel. Diflufenican showed much stronger sorption to the soil than to the gravel, while the sorption of the metabolites was weaker than diflufenican in both soil and gravel. Within the experimental period, the influence of aging on the fate of diflufenican in soil and gravel is limited (<0.9 and <1.4%, respectively) when compared to the amount of compound still present in the soil. Overall, the results imply shortcomings in the risk assessment procedures requested for the registration of pesticides for urban areas.

Stormwater retention ponds receive a variety of urban and highway pollutants that may have adverse effects on water-dwelling organisms. In this exploratory study, the benthic diatom community composition at genus level of nine such ponds servicing highway, residential, industrial, and mixed industrial/residential catchments was examined. Thirteen biocides were measured in the pond water as one of the possible explanatory factors for diatom taxonomic variability. The uppermost 1 cm of sediment was sampled, and a total of 50 diatom genera were identified. Moderate to high similarities were found among the diatom communities of the ponds. Two genera, namely Navicula and Nitzschia, were the most abundant and accounted for 19–47% of the relative abundance in the ponds. Estimated relative abundances of diatom genera and measured biocide concentrations in the ponds were grouped according to land use. Highway ponds were found to be significantly different from ponds servicing residential and industrial catchments, while no significant differences were found between residential and industrial ponds. The presence of biocides alone could not explain diatom taxonomic variability, although some evidence was found that communities differed depending on the catchment type of the ponds. The results of this exploratory study are an important contribution to future works investigating stormwater diatom communities, where combined effects of biocides and other stormwater contaminants and community stressors, e.g., metals, PAHs, road salt, should be explicitly looked at.

The cyanoacrylate ethyl (2Z)-3-amino-2-cyano-3-phenylacrylate (phenamacril), has been introduced as an effective agent against several fungi species belonging to the Fusarium genus. However, in current literature, knowledge about the environmental behavior of this fungicide is limited and there are no data on the degradation in the environment. By performing tests on inherent degradability as well as degradation studies in soils this study provides the only published information regarding the environmental stability and degradation kinetics of this compound. Tests for inherent/ready biodegradation revealed the phenamacril is inherently degradable with zero order kinetics, even though the degradation is comparatively slow. Degradation of phenamacril in soil was found to occur following first order kinetics with a final plateau with a half live of 17.1 days (i.e. more rapidly than tebuconazole but less rapidly than octylisothiazolinone).

Biocides - added to facade coatings like paints and renders to reduce microbial growth on the outer surfaces of buildings - are known to leach into the environment, when the facades are getting in contact with rainwater. The leaching process is described as diffusion controlled process. Nevertheless, no comprehensive data on diffusion coefficients is available so far. The present study aimed for determining the diffusion coefficients in paint of eight biocides, applying an easy, reproducible method. The study was performed using a paint closely related to commercially available paints. It suggests a new method to determine diffusion coefficients in paint films by submerging paint films consisting of several layers with water for 1 h intervals over a period of 30 h. By determining the biocide concentrations in the water after the contacting time, the mass flow of biocides across the paint film was calculated. The resulting diffusion coefficients varied from (0.27 +/- 0.07).10(-15)m(2) s(-1) for Cybutryn to (11.97 +/- 3.14).10(-15)m(2) s(-1) for Diuron.

Biofilm reactors are a promising biotechnology to eliminate pharmaceuticals from wastewater during tertiary treatment or in water works for drinking water production. This study aimed at investigating the effects of pulsed carbon feeding for promoting the co-degradation of indigenous pharmaceuticals from pre-treated wastewater in a fixed-bed porous biofilm reactor (slow sand filter). The addition of acetate (carbon source) resulted in three different enhancement/limitation effects, which were compound dependent: 1) atenolol and iohexol experienced enhanced co-degradation followed by constant (acetate independent) degradation; 2) metoprolol, iomeprol, diclofenac, propranolol and sulfamethizole co-degradation dependent on aerobic turnover, but inhibited at higher acetate concentrations (60 -300 mg C/L); 3) sulfadiazine, sulfamethoxazole and trimethoprim were removed independently of oxygen and acetate concentration. Carbamazepine, ditriazoic acid, iopromide; tramadol and venlavaxine were not removed at any acetate dosage. Biofilm reactors can be employed for polishing treated wastewater, and the addition of a primary carbon source can enhance the performance of the bioreactor. (C) 2019 Elsevier Ltd. All rights reserved.