Denis Mihailescu

Urban rainwater is an increasingly important alternative water resource, but its suitability for harvesting and reuse depends on a water quality that varies strongly with local emissions and season—a variability not previously characterised for Bucharest, the Romanian capital. This study addresses that gap by evaluating the physicochemical quality of directly collected rainwater at six contrasting sites (four traffic-influenced, two urban-green) in District 1, Bucharest, over 37 rainfall events sampled between January and November 2025. Samples were analysed for pH, electrical conductivity, turbidity, true colour, total hardness, chloride, inorganic nitrogen species (NO₃⁻–N, NO₂⁻–N, NH₄⁺–N) and trace metals (Zn, Cd, Pb), and interpreted using descriptive statistics, Pearson’s correlation and Principal Component Analysis (PCA). Traffic-influenced sites were consistently more contaminated than urban-green sites, with mean concentrations higher by 47% for electrical conductivity (EC), 64% for cadmium and 67% for zinc. PCA resolved two factors: traffic-related particulate pollution (Cd, Pb, Zn) and secondary atmospheric nitrogen processing. Cadmium reached the World Health Organisation (WHO) indicative guideline, and lead exceeded the European Union (EU) parametric value at traffic sites, while ammonium exceeded 0.50 mg/L in most traffic-site events. These findings show that harvested rainwater quality is strongly site-dependent and that high-traffic locations require targeted treatment before any potable reuse.

Polychlorinated biphenyls (PCBs) are synthetic organic compounds that were widely used in industrial applications throughout the 20th century. Due to their chemical stability, resistance to degradation and ability to bioaccumulate and biomagnify through food chains, PCBs pose long-term environmental and health risks. Due to these characteristics, PCBs have been globally regulated as persistent organic pollutants (POPs), despite being banned from production in most countries decades ago. This study investigates temporal trends in PCB contamination in urban soils of Bucharest over a 20-year period (2002–2022), focusing on six principal congeners (PCB 28, 52, 101, 138, 153, and 180) sampled from 13 locations, including roadsides and urban parks. Gas chromatography and spatial analysis using inverse distance weighting (IDW) revealed a marked reduction in Σ6PCB concentrations, declining from 0.0159 mg/kg in 2002 to 0.0065 mg/kg in 2022, with statistically significant differences confirmed by Kruskal–Wallis analysis (p < 0.05). This decline is primarily attributed to reduced emissions, source control measures, and natural attenuation. However, the persistence of PCBs in localized hotspots is influenced by secondary dispersion mechanisms, such as atmospheric deposition and surface runoff, which redistribute contaminants rather than eliminate them. Health risk assessments via ingestion, dermal absorption, and inhalation routes confirmed negligible carcinogenic risk for both adults and children. Although measurable progress has been achieved, the persistence of localized contamination underscores the need for targeted remediation strategies and sustained environmental monitoring to protect vulnerable urban areas from recontamination.

Land degradation (LD) and desertification (DS) are a sensitive global issue including southern and south-eastern Europe, which is severely affected by climate change. In this study, a state-of-the-art approach for assessing the intensity of LD and DS processes using remote-sensing-derived indicators within a GIS environment was proposed. The analysis was carried out using the Principal Component Analysis based on integrating the significant trends of relevant biophysical parameters in Romania. The methodology was tested and validated at the national level in Romania. In total, 7.76% of the area was identified as LD and 60.8% of the total area tended to improve, and 31.44% was stable. Most of the regions with LD overlapped with the dryland areas, while improvement areas were identified outside of the drylands. In forested areas from high altitudes, a tendency to improve the condition of vegetation was observed, and most of the surfaces being protected were natural areas that have benefited from proper management. All these results can be used to adapt management practices to avoid, reduce, or restore the LD. The proposed model was based on globally available remote sensing datasets, with a high frequency of data acquisition and collection history that allows for the statistical analyses of changes on a global scale.

This paper will assess the sensitivity of soil moisture anomaly (SMA) obtained from the Soil water index (SWI) product Metop ASCAT, to identify drought in Romania. The SWI data were converted from relative values (%) to absolute values (m³ m⁻³) using the soil porosity method. The conversion results (SM) were validated using soil moisture in situ measurements from ISMN at 5 cm depths (2015–2020). The SMA was computed based on a 10 day SWI product, between 2007 and 2020. The analysis was performed for the depths of 5 cm (near surface), 40 cm (sub surface), and 100 cm (root zone). The standardized precipitation index (SPI), land surface temperature anomaly (LST anomaly), and normalized difference vegetation index anomaly (NDVI anomaly) were computed in order to compare the extent and intensity of drought events. The best correlations between SM and in situ measurements are for the stations located in the Getic Plateau (Bacles (r = 0.797) and Slatina (r = 0.672)), in the Western Plain (Oradea (r = 0.693)), and in the Moldavian Plateau (Iasi (r = 0.608)). The RMSE were between 0.05 and 0.184. Furthermore, the correlations between the SMA and SPI, the LST anomaly, and the NDVI anomaly were significantly registered in the second half of the warm season (July–September). Due to the predominantly agricultural use of the land, the results can be useful for the management of water resources and irrigation in regions frequently affected by drought.

The aim of this study is to analyze the performance of the Drought Severity Index (DSI) in Romania and its validation based on other data sources (meteorological data, soil moisture content (SMC), agricultural production). Also, it is to assess the drought based on a multi-temporal analysis and trends of the DSI obtained from Terra MODIS satellite images. DSI is a standardized product based on evapotranspiration (ET) and the Normalized Difference Vegetation Index (NDVI), highlighting the differences over a certain period of time compared to the average. The study areas are located in Romania: three important agricultural lands (Oltenia Plain, Baragan Plain and Banat Plain), which have different environmental characteristics. MODIS products have been used over a period of 19 years (2001–2019) during the vegetation season of the agricultural crops (April–September). The results point out that those agricultural areas from the Baragan Plain and Oltenia Plain were more affected by drought than those from Banat Plain, especially in the years 2002, 2007 and 2012. Also, the drought intensity and the agricultural surfaces affected by drought decreased in the first part of the vegetation season (March–May) and increased in the last part (August–September) in all three study areas analyzed. All these results are confirmed by those of the Standardized Precipitation Evapotranspiration Index (SPEI) and Soil Moisture Anomaly (SMA) indices.

We suggest that the unprecedented and unintended decrease of emissions of air pollutants during the COVID-19 lock-down in 2020 could lead to declining seasonal ozone concentrations and positive impacts on crop yields. An initial assessment of the potential effects of COVID-19 emission reductions was made using a set of six scenarios that variously assumed annual European and global emission reductions of 30% and 50% for the energy, industry, road transport and international shipping sectors, and 80% for the aviation sector. The greatest ozone reductions during the growing season reached up to 12 ppb over crop growing regions in Asia and up to 6 ppb in North America and Europe for the 50% global reduction scenario. In Europe, ozone responses are more sensitive to emission declines in other continents, international shipping and aviation than to emissions changes within Europe. We demonstrate that for wheat the overall magnitude of ozone precursor emission changes could lead to yield improvements between 2% and 8%. The expected magnitude of ozone precursor emission reductions during the Northern Hemisphere growing season in 2020 presents an opportunity to test and improve crop models and experimentally based exposure response relationships of ozone impacts on crops, under real-world conditions. This article is part of a discussion meeting issue ‘Air quality, past present and future’.

Land cover is one of the key terrestrial variables used for monitoring and as input for modelling in support of achieving the United Nations Strategical Development Goals. Global and Continental Land Cover Products (GCLCs) aim to provide the required harmonized information background across areas; thus, they are not being limited by national or other administrative nomenclature boundaries and their production approaches. Moreover, their increased spatial resolution, and consequently their local relevance, is of high importance for users at a local scale. During the last decade, several GCLCs were developed, including the Global Historical Land-Cover Change Land-Use Conversions (GLC), the Globeland-30 (GLOB), Corine-2012 (CLC) and GMES/ Copernicus Initial Operation High Resolution Layers (GIOS). Accuracy assessment is of high importance for product credibility towards incorporation into decision chains and implementation procedures, especially at local scales. The present study builds on the collaboration of scientists participating in the Global Observations of Forest Cover—Global Observations of Land Cover Dynamics (GOFC-GOLD), South Central and Eastern European Regional Information Network (SCERIN). The main objective is to quantitatively evaluate the accuracy of commonly used GCLCs at selected representative study areas in the SCERIN geographic area, which is characterized by extreme diversity of landscapes and environmental conditions, heavily affected by anthropogenic impacts with similar major socio-economic drivers. The employed validation strategy for evaluating and comparing the different products is detailed, representative results for the selected areas from nine SCERIN countries are presented, the specific regional differences are identified and their underlying causes are discussed. In general, the four GCLCs products achieved relatively high overall accuracy rates: 74–98% for GLC (mean: 93.8%), 79–92% for GLOB (mean: 90.6%), 74–91% for CLC (mean: 89%) and 72–98% for GIOS (mean: 91.6%), for all selected areas. In most cases, the CLC product has the lower scores, while the GLC has the highest, closely followed by GIOS and GLOB. The study revealed overall high credibility and validity of the GCLCs products at local scale, a result, which shows expected benefit even for local/regional applications. Identified class dependent specificities in different landscape types can guide the local users for their reasonable usage in local studies. Valuable information is generated for advancing the goals of the international GOFC-GOLD program and aligns well with the agenda of the NASA Land-Cover/Land-Use Change Program to improve the quality and consistency of space-derived higher-level products.

Drought is one of the most significant extreme event facing the world, affecting the society and the environment. Located in SE Romania, Dobrogea Region is characterized by a temperate climate with strong continental influences, being affected by drought episodes which cause significant damages and economic costs over extensive agricultural areas. Risk reduction, continuous vegetation monitoring, and management implementation are facilitated by complementary use of vegetation indices and biophysical parameters derived from satellite products (gridded data) within-situ data (point data). The paper focuses on:i) evaluating the extent and intensity of drought in Dobrogea, Romania, based on Normalized Difference Drought Index (NDDI) and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR); ii) fires analysis, based on the Thermal Anomalies/Fire locations product (MCD14DL); iii)the correlation between the fires with the NDDI; iv) and the correlation between fires with the Land Surface Temperature (LST) product. The vegetation indices, biophysical parameters and fires are computed from Moderate Resolution Imaging Spectroradiometer (MODIS) daily and eight days’ synthesis products, during 22^th of March - 29^th of August 2000-2015. The results highlight the areas most affected by drought (moderate, severe and extreme) and fires in the Dobrogea.