Air quality changes in NE Romania during the first Covid 19 pandemic wave.

This study analyzes for the first time uniformly and causally the level of pollution and air quality for the NE-Romania Region, one of the poorest region in the European Union. Knowing the level of pollution and air quality in this region, which can be taken as a benchmark due to its positional and economic-geographical attributes, responds to current scientific and practical needs. The study uses an hourly database (for five pollutants and five climate elements), from 2009 to 2020, from 19 air quality monitoring stations in northeastern Romania. Pollutant levels were statistically and graphically/cartographically modeled for the entire 2009-2020 interval on the distributive-spatial and regime, temporal component. Inter-station differences and similarities were analyzed causally. Taking advantage of the emergency measures between March 16 and May 14, 2020, we observed the impact of the event on the regional air quality in northeastern Romania. During the emergency period, the metropolitan area of Suceava (with over 100,000 inhabitants) was quarantined, which allowed us to analyze the impact of the quarantine period on the local air quality. We found that, in this region, air quality falls into class I (for NO2, SO2 and CO), II for O3 and III for PM10. During the lockdown periods NO2 and SO2 decreased for the entire region by 8.6 and 14.3%, respectively, and in Suceava by 13.9 and 40.1%, respectively. The causes of the reduction were anthropogenic in nature.

Orthotidal signal in the electrical conductivity of an inland river.

An orthotidal signal is a tidal component found in a streamwater parameter when there is no oceanic tidal input, i.e. when the streamwater monitoring point is located far inland and at high elevation. This study analyses various parameters of Cib River in Carpathian Mountains, Romania. This river receives water from a rich karst aquifer when crossing Cib Gorge. Streamwater level, temperature and electrical conductivity were measured in 270 days grouped in three time intervals of consecutive days. The measurements were done every 15 minutes in order to capture any significant periodic variation. The streamwater measurements were paired with air measurements and measurements done in a thermal spring. Solar semidiurnal oscillations were found in the streamwater electrical conductivity. In case study time series, selected based on their good signal to noise ratio, there are average semidiurnal oscillations of approximately 4 µS/cm, while the maximum amplitude rise up to 20 µS/cm. The semidiurnal peaks in water are generally in phase with the two atmospheric tide maxima, which are the cause of the studied phenomenon. The higher mineralisations of the thermal waters that rise from beneath the karst aquifer are the most probable cause of finding significant orthotides only in the electrical conductivity time series of the studied river.

Climatic water deficit and surplus between the Carpathian Mountains and the Dniester River (1961-2012).

The study addresses the climatic water deficit (WD) and surplus (WE) in the area located between the heights of the Eastern Carpathians (Romania) and the Dniester River (Moldova). The objective of this study is to discover the trend of WD/WE (past and future) and its variation in space. WD and WE were calculated as the difference between the amounts of precipitation (P) and the reference evapotranspiration (ET0). The P-ET0 trend, analyzed through Mann-Kendall and t tests, was negative for 83 and 80% of the analyzed stations and the Sen's slope had values between - 0.05 mm year-1 (t test) and - 6.73 mm year-1 (Mann-Kendall test). Seasonally, the slope values of P-ET0 trends were negative during winter, spring, and summer and positive in autumn. The P-ET0 index is positive (WE) only in the Carpathian and Eastern Subcarpathian areas, whereas for the rest of the investigated territory, we found negative values (WD). WD is more pronounced as we depart from the Carpathians towards the east, but also on a north to south direction, reaching the maximum in the southeastern part of the territory. In what concerns seasonal distribution, WE is identified everywhere only in winter, whereas, in spring, summer, and autumn, WD characterizes most of the territory, with the exception of the Carpathian and Subcarpathian areas. The increasing WD will have a growing negative influence on the agriculture of the studied area. For the year 2030, we anticipate a reduction in the climate water availability with 46 mm m-2 (reference period: 1961-2012).