Abstract. The evolving nature of the COVID-19 pandemic necessitates timely estimates of the resultant perturbations to anthropogenic emissions. Here we present a novel framework based on the relationships between observed column abundance and wind speed to rapidly estimate the air-basin-scale NOx emission rate and apply it at the Po Valley in Italy using OMI and TROPOMI NO2 tropospheric column observations. The NOx chemical lifetime is retrieved together with the emission rate and found to be 15–20 h in winter and 5–6 h in summer. A statistical model is trained using the estimated emission rates before the pandemic to predict the trajectory without COVID-19. Compared with this business-as-usual trajectory, the real emission rates show three distinctive drops in March 2020 (−42 %), November 2020 (−38 %), and March 2021 (−39 %) that correspond to tightened COVID-19 control measures. The temporal variation of pandemic-induced NOx emission changes qualitatively agrees with Google and Apple mobility indicators. The overall net NOx emission reduction in 2020 due to the COVID-19 pandemic is estimated to be 22 %.

Pollutants from personal care products (PCPs), pharmaceuticals, industrial wastes, food additives, pesticides and fertilisers are classified as emerging contaminants (ECs). These ECs have been given much attention due to their deleterious effects on human life, plants and animals. Triclosan (TCS), a broad spectrum antibiotic, is under the category of emerging contaminants; it is shown to have an eco-toxicity. It is a ubiquitous contaminant due to its wide range of applications in PCPs as an antibacterial agent. Inefficacy in the conventional treatment of wastewater which is being discharged into natural streams has led to the bioaccumulation of TCS. Concentrations of TCS have been detected in several wastewater treatment plants and urinary samples of humans and streams. In surface waters, TCS was detected in Korea, USA, Europe, China, Japan and India. In order to overcome the astringent effects of TCS, there is a need for its treatment. This paper addresses studies conducted on methods of treating TCS, and among all the methods, membrane technology (MT) was found to be effective and this is mainly due to hydrophilic nature of TCS, high log K ow value (4.8), and a removal efficiency > 95% was observed when powdered activated carbon of 100 mg/l was combined with MT.

Abstract. The evolving nature of the COVID-19 pandemic necessitates timely estimates of the resultant perturbations to anthropogenic emissions. Here we present a novel framework based on the relationships between observed column abundance and wind speed to rapidly estimate air basin-scale NOx emission rate and apply it at the Po Valley in Italy using OMI and TROPOMI NO2 tropospheric column observations. The NOx chemical lifetime is retrieved together with the emission rate and found to be 15–20 h in winter and 5–6 h in summer. A statistical model is trained using the estimated emission rates before the pandemic to predict the trajectory without COVID-19. Compared with this business-as-usual trajectory, the real 2020 emission rates show two distinctive drops in March (−41 %) and November (−35 %) that correspond to tightened COVID-19 control measures. The temporal variation of pandemic-induced NOx emission changes qualitatively agree with Google and Apple mobility indicators. The overall net NOx emission reduction in 2020 due to the COVID-19 pandemic is estimated to be 21 %.

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