A method for evaluating the pharmaceutical deconjugation potential in river water environments

Modelling micropollutant cycle in Lake Como in a winter scenario: Implications for water use and reuse, ecosystem services, and the EU zero pollution action plan

The fate and effects of 42 pharmaceuticals was studied in Lake Como (Italy), in wastewater treatment plants delivering water to the lake, in two rivers and in potable water obtained from lake water. Lake Como is one of the deepest and largest lakes in Northern Italy, serving important ecosystem services (i.e., drinking water, recreational, industrial, irrigation uses), some of which are currently at risk giving the current water scarcity and climate change scenarios. The highest concentrations measured in lake water were those of diclofenac, followed by carbamazepine, its metabolite, and clarithromycin. The data measured allowed to calibrate and run a fugacity-based lake model, which showed that the most important chemical load generally comes from the advective water from the north of the lake, rather than from the direct wastewater treatment plant (WWTP) discharges. This indicates that only an important reduction of chemical discharge (reduced use or extensive treatment) at a drainage basin level could significantly reduce concentrations in water. This has strong implications on how to implement the EU zero pollution action plan to significantly improve water ecosystem and human health protection.

Possible overestimation of bisphenol analogues in municipal wastewater analyzed with GC-MS

This work for the first time showed that sulfated BPA could be directly analyzed as BPA with GC-MS after the derivatization with N,O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA)+1% trimethylchlorosilane (TMCS), i.e. the deconjugation step was not necessary. This was because sulfated BPA indeed could be simultaneously deconjugated and derivatized to BPA derivative during derivatization, suggesting that any co-elution of BPA and sulfated BPA during sample extraction led to BPA overestimation in the GC-MS method with BSTFA +1% TMCS as the derivative reagent. Using BPA 4,4'-disulfates (BPA diS) as the pure standard, the co-elution phenomena of sulfated BPA was confirmed with two widely used elution solvents (i.e. methanol and ethyl acetate) or their mixed solutions with different ratios, which further suggested if only sulfated BPA existed in any wastewater sample, BPA was likely over-determined. To further confirm this finding, both influent and effluent samples collected from a local municipal wastewater treatment plant were analyzed, which clearly showed the overestimation of BPA in the two wastewaters due to co-existence of sulfated BPA in the wastewater samples. In addition to BPA, the results also showed the overestimation of other nine bisphenol analogues. As sulfated micropollutants including estrogens, androgens, phytoestrogens, etc., have been widely found in municipal wastewater, the overestimating phenomenon observed in this study may also be extended to determination of other micropollutants, which should be addressed in future.

Strategy for effective inhibition of arylsulfatase/β-glucuronidase to prevent deconjugation of sulfate and glucuronide conjugates in wastewater during sample collection and storage

Arylsulfatase and β-glucuronidase are two important enzymes that are responsible for deconjugation of estrogen conjugates. It is important to keep estrogen conjugates intact during sample collection and storage, while the effective inhibition conditions for arylsulfatase and β-glucuronidase remain unknown. To elucidate these conditions, inhibition experiments were performed by adding several inhibitors or by introducing extreme pH conditions. This work confirms that arylsulfatase and β-glucuronidase can tolerate some extremes, including high concentrations of mercury dichloride, ethanol, and EDTA, while low pH (<3) or high pH (>11) can effectively inhibit their activities. The high tolerance of arylsulfatase and β-glucuronidase for mercury dichloride explains why estrogen conjugates in wastewater samples were deconjugated, even in the extremely unfavorable condition with a high concentration of mercury dichloride. Although low pH (<3) can effectively inhibit arylsulfatase/β-glucuronidase, deconjugation of sulfate conjugates by acid hydrolysis readily occurs; thus, a high pH of 11 is an appropriate storage condition for the effective inhibition of arylsulfatase/β-glucuronidase. This appropriate storage condition was confirmed and validated with diluted and sterilized activated sludge samples in which arylsulfatase/β-glucuronidase inhibition was effective for 48 h at room temperature and with a high pH of 11. The developed appropriate storage condition for effective inhibition of arylsulfatase/β-glucuronidase has wide application potential not only for estrogen conjugates but also for all conjugates of other organic micropollutants.

A fugacity model assessment of ibuprofen, diclofenac, carbamazepine, and their transformation product concentrations in an aquatic environment

An updated version of FATEMOD, a multimedia fugacity model for environmental fate of organic chemicals, was set up to assess environmental behaviour of three pharmaceuticals in northern Lake Päijänne, Finland. Concentrations of ibuprofen, diclofenac, and carbamazepine were estimated at various depths at two sites: near a wastewater treatment plant and 3.5 km downstream the plant. When compared with environmental sampling data from corresponding depths and sites, the predicted concentrations, ranging from nanograms to hundreds of nanograms per litre, were found to be in good agreement. Weather data were utilised with the model to rationalise the effects of various environmental parameters on the sampling results, and, e.g. the roles of various properties of lake dynamics and photodegradation were identified. The new model also enables simultaneous assessment of transformation products. Environmentally formed transformation product concentrations were estimated to be at highest an order of magnitude lower than those of the parent compounds, and unlikely to reach a detectable level. However, a possibility that conjugates of ibuprofen are present at higher levels than the parent compound was identified. Simulation results suggest that environmental degradation half-lives of the inspected contaminants under stratified lake conditions are in the range of some weeks to months.