Occurrence Of Transformation Products Research Articles

Identification of lower brominated bisphenol A analogs as the photooxidation products of tetrabromobisphenol A bis(2,3-dibromopropyl) ether (TBBPA-BDBPE)

The transformation products and mechanism of tetrabromobisphenol A (TBBPA) derivatives are still largely unknown compared with TBBPA. In this paper, sediment, soil and water samples (15 sites, 45 samples) collected in a river flowing through brominated flame retardant manufacturing zone were analyzed to determine TBBPA derivatives, byproducts, and transformation products. TBBPA derivatives and byproducts were detected with concentrations ranging from none detection to 1.1 × 104 ng/g dw and with detection frequencies of 0–100 % in all samples. The concentrations of TBBPA derivatives such as TBBPA bis(2,3-dibromopropyl) ether (TBBPA-BDBPE) and TBBPA bis(allyl ether) in sediment and soil samples were higher than that of TBBPA. In addition, the occurrence of various unknown bromobisphenol A allyl ether analogs in the samples was further confirmed by using 11 synthesized analogs, which might be produced during the waste treatment process of the factories. The possible transformation pathways of TBBPA-BDBPE were revealed for the first time by using UV/base/persulfate (PS) as designed photooxidation waste treatment system in the laboratory. Ether bond cleavage, debromination, and β-scission contributed to the transformation of TBBPA-BDBPE and the occurrence of transformation products in the environment. The concentrations of the transformation products of TBBPA-BDBPE ranged from none detection to 3.4 × 102 ng/g dw. These data provide new insights into the fate of TBBPA derivatives in environmental compartments.

Reacqua: A low-cost solar still system for the removal of antibiotics from contaminated effluents

The use of antibiotics in intensive animal production and human medical treatment can result in a significant discharge of those drugs and its transformation products in faeces and urine that contaminate water bodies. The effluents produced by poultry and pig production plants are often discharged without any treatment in the environment. These effluents can contain high levels of active drugs and several by-products. The contamination of water sources with these contaminants is of emerging concern for human health and the environment. The search for treatment processes capable of removing antibiotics from water is an urgent need, especially in rural zones that lack of wastewater treatment plants. A solar still system was used for removal and degradation of a mixture of several veterinary antibiotics widely used in poultry and pig intensive production. Water samples (10 L) containing enrofloxacin, oxytetracycline, sulfadimethoxine, sulfaquinoxaline, sulfamethazine, and sulfamethoxazole within the concentration range of 20–500 mg L−1 were processed in the system. The experiment was carried out in filed conditions in duplicate (Summer and Winter). The occurrence of transformation products was also investigated to elucidate the degradation pathways. The system was able to remove antibiotics in a range from 99.73% to more than 99.99%.

Biotransformation of pregabalin in surface water matrices and the occurrence of transformation products in the aquatic environment - comparison to the structurally related gabapentin

The biodegradability of the anticonvulsant pregabalin (PGB) was studied in laboratory incubation experiments in contact with water/sediment systems under different redox conditions. PGB was degraded by biological processes under aerobic conditions reaching half-lives of 8 to 10 d, while inactivated and anaerobic control experiments revealed no significant decrease of PGB concentrations. Within experiments spiked with elevated PGB concentrations, 12 TPs were formed and tentative chemical structures could be proposed by accurate masses and fragmentation pathways detected via measurements with high resolution mass spectrometry (LC-QToF-MS). Four of the proposed TPs were finally confirmed either by authentic reference standards (PGB-Lactam, ISA, TP 157-A (II)) or a self-synthesized standard (NA-PGB). PGB-Lactam was identified as the quantitatively most relevant TP formed via intramolecular cyclization under aerobic conditions, reaching up to 33% of the initial PGB concentration. Incubation experiments spiked with PGB-Lactam revealed three times higher half-lives compared to the parent compound, indicating that PGB-Lactam is more stable than PGB. A comparison with results gained from water/sediment incubation experiments with the structurally related compound gabapentin (GBP) revealed, that the transformation behaviour can be mainly extrapolated to PGB. Most of the observed transformation reactions found for PGB were comparable to the ones found for GBP. The TPs PGB-Lactam and NA-PGB as well as three GBP TPs (GBP-Lactam, NA-GBP and CCHA) have been detected in German wastewater treatment plants (WWTPs) effluents and the river Rhine including some of its tributaries such as Main, Neckar, Moselle and Aare. Moreover, GBP and PGB as well as some of their TPs were detected in German bank filtrates and finished drinking waters up to 260 ng L-1. For that reason these compounds should be monitored in drinking water in the future.

Abiotic and biotic transformation of torasemide - Occurrence of degradation products in the aquatic environment

The pharmaceutical torasemide is an important loop diuretic and was 2017 one of the ten most prescribed drugs in Germany. Despite its detection in different compartments of the urban water cycle including drinking water, no studies were so far performed to elucidate its fate in the environment and the occurrence of transformation products (TPs). Therefore, we investigated the phototransformation, microbial degradation, transformation with human liver microsomes and anodic oxidation of torasemide to obtain good coverage of environmentally relevant degradation products. Overall sixteen products were identified, covering the following reaction mechanisms: aromatic and aliphatic hydroxylation, including further oxidation to carboxylic acids and quinone imines, amide cleavage, N-dealkylation, N-dearylation, and sulfonamide hydrolysis to sulfonic acids. Especially the formation of quinone imines could be of concern as they are highly reactive electrophiles. Torasemide itself was observed in all investigated wastewater treatment plant (WWTP) samples and wastewater-impacted surface waters. The maximum detected concentration was about 350 ng L−1. Only three of the sixteen transformation products were generally observed in at least one of the samples and the most frequently detected TPs were the human metabolites hydroxytorasemide (TP 364a) and carboxytorasemide (TP 378a). The complete removal of TP 364a during wastewater treatment was in agreement with the results of microbial degradation experiments. TP 364a was most likely transformed into TP 378a, which was microbially less degraded in lab experiments. Based on estimated concentrations, TP 378a could reach about 1 μg L−1 in the investigated wastewater matrices.

Biotransformation of pharmaceuticals in surface water and during waste water treatment: Identification and occurrence of transformation products

Venlafaxine, gemfibrozil, ibuprofen, irbesartan and ofloxacin are highly-consumed pharmaceuticals that show considerable removal efficiencies (between 40 and 98%) in wastewater treatment plants (WWTPs). Consequently, they are expected to generate transformation products (TPs) during wastewater treatment and in surface water (SW) receiving WWTP effluent. In this work, degradation experiments for these five pharmaceuticals have been carried out with SW and WWTP activated sludge under laboratory-controlled aerobic conditions to identify their transformation products by liquid chromatography coupled to time-of-flight mass spectrometry (LC–QTOF MS). Initially, 22 pharmaceutical TPs were tentatively identified. A retrospective analysis was performed in effluent wastewater (EWW) and SW samples. All parent compounds as well as several TPs were found in some of the selected EWW and SW samples. Additionally, valsartan and 3 TPs were also detected by searching for common fragments in these waters. It is important to highlight that some TPs, such as O-desmethyl-venlafaxine and an oxidized gemfibrozil TP, were more frequently found than their corresponding parent compounds. On the basis of these results, it would be recommendable to include these TPs (at least those found in EWW and SW samples analyzed) in monitoring programs in order to gain a more realistic understanding of the impact of pharmaceuticals on water quality.

Leaching of Biocides from Façades under Natural Weather Conditions

Biocides are included in organic building façade coatings as protection against biological attack by algae and fungi but have the potential to enter the environment via leaching into runoff from wind driven rain. The following field study correlates wind driven rain to runoff and measured the release of several commonly used organic biocides (terbutryn, Irgarol 1051, diuron, isoproturon, OIT, DCOIT) in organic façade coatings from four coating systems. During one year of exposure of a west oriented model house façade in the Zurich, Switzerland area, an average of 62.7 L/m(2), or 6.3% of annual precipitation came off the four façade panels installed as runoff. The ISO method for calculating wind driven rain loads is adapted to predict runoff and can be used in the calculation of emissions in the field. Biocide concentrations tend to be higher in the early lifetime of the coatings and then reach fairly consistent levels later, generally ranging on the order of mg/L or hundreds of μg/L. On the basis of the amount remaining in the film after exposure, the occurrence of transformation products, and the calculated amounts in the leachate, degradation plays a significant role in the overall mass balance.