The main idea for the Online First publishing (i.e. publishing an electronic version of the article in advance of the print edition) lies in considerably reducing the time it would have previously taken for research to reach the research community. Online-first papers have been peer-reviewed and accepted for publication in this journal and posted online before final publication in a volume.
Once a proof has been corrected and finalized, an article is ready for Online First publication and can be published online. This means that readers can access peer reviewed articles well before print publication. The articles have been copy edited and author corrections have been incorporated before they are posted online. Type setting and proofreading will commence with electronic publication, and the volume, issue and page numbers will then be assigned to the final version of the article.
Online-first articles should be cited with the DOI link.
2026
BLANKA BARTÓK 
Changes in solar radiation extremes and their impact on the solar power generation in Europe.
pp: 1 – 16 | DOI: https://doi.org/10.24193/RCJ2026_1| Full text | Suplimentary material
Present study focuses on distribution of low surface solar radiation (overcast situation) and high surface solar radiation (clear sky situation), since, the frequencies of these situations have high impact on the electricity generation. The results show a shift in the distributions projected for the period of 2065-2100 based on 56 high-resolution EURO-CORDEX simulations (RCP8.5). In the northern countries a shift towards lower values is detected. The changes are more accentuated in wintertime, when the low extremes are becoming lower by 16%, the high extremes decrease with 8%. These tendencies are detected in the central part of the continent as well, however, the changes are smaller, -10% in case of low values, and 5% for high values. In the southern part of the continent the shift of distribution has opposite direction. In these countries, the low surface solar radiation values are becoming higher by 4% in summertime; on the other hand, there is no significant change in high extremes (+1%). The shift of extreme values might have serious impact on solar power generation, since it could induce even 20-25 extra days with low radiation in the norther regions, while in the southern regions 15-20 extra days with high radiation are projected.
ANDREA GÁL*, ZOLTÁN IMECS, BÉLA BALÁZS, BOGLÁRKA CZELLECZ
Impact of wheel track erosion on the Briței crocus heuffelianus field.
pp: 17 – 32 | DOI: https://doi.org/10.24193/RCJ2026_2| Full text |
This study examines the impact of off-road vehicle traffic and associated “floral tourism” on the population of Crocus heuffelianus within the Briței floral field. As social media-driven tourism increases, sensitive ecosystems face new anthropogenic pressures that threaten the long-term viability of rare botanical species. The analysis is based on aerial imagery captured via UAV across three sample areas in May 2021. Photogrammetric reconstruction of the UAV imagery into high-resolution digital surface models (DSMs) enabled the quantification of floral coverage, the extent of habitat fragmentation, and the direct mechanical footprint of wheel-track erosion on the C. heuffelianus population. The findings reveal a significant C. heuffelianus prevalence, with floral cover ranging between 15,9% and 26,0% (average 20,1%). However, habitat fragmentation varied significantly, reaching a peak of 5,41 m2/100 m2 in the most disturbed plots. High fragmentation indices (4 m2/100 m2) and direct spatial coincidence between vehicle trajectories and dense floral clusters resulted in a 2,8% loss of total floral area. Total population estimates exceed 30 million specimens, yet wheel-track erosion and associated soil compaction are responsible for a total loss of over 900000 individuals.
SIPHUMZE BANI, ROMAN TANDLICH*, BRENDAN WILHELMI
Microbial risk assessment and hazards associated with greywater and wastewater recycling in South Africa: a review.
pp: 33 – 66 | DOI: https://doi.org/10.24193/RCJ2026_3| Full text |
Sustainable water security and management in South Africa have challenges that include climate change impacts, increasing water demand, and dysfunctional infrastructure. These challenges result in the necessity for additional water management and reclamation strategies. Greywater (domestic wastewater) has been recognized for its potential for treatment and reuse for non-potable purposes such as toilet-flushing, irrigation, and firefighting. This wastewater management strategy has been highlighted as important because greywater is produced in large quantities and has low to medium pollution levels. The benefits of this strategy are not only related to the decreasing of freshwater use but also to preparedness for emergency disasters such as disease outbreaks (provision of consistent sanitation and hygiene) and urban/rural fires. Various greywater treatment systems (GWTs) have been operated, evaluated, and implemented. The threat from the implementation of GWTs is the recalcitrant microbial content in treated greywater which pose health risks to the environment and when reused for mentioned non-potable purposes. This is assessed by the low microbial removal efficiencies of different GWTs. Risk assessment methods from previous studies are considered, for example, the Quantitative Microbial Risk Assessment (QMRA), and Cumulative Risk Rating (CRR). This review presents a framework for a microbial risk assessment approach in the context of greywater treatment and reuse in South Africa.
NÓRA-CSILLA VERESS
The Cluj metro project. Issues and challenges.
pp: 67 – 84 | DOI: https://doi.org/10.24193/RCJ2026_4| Full text |
Recently, excavations had started in Cluj-Napoca for the building of Romania’s second metro line after Buchrest, which is expected to resolve the problem of daily traffic and overwhelmed streets. However, the planning and the implementation of the project face issues and challanges regarding first of all environmental impacts, as the route crosses a protected arheological and cultural area, which is very densely populated and has busy traffic on one hand and instabil soil on the other hand. Thus, the project requires comprehensive feasibility studies, field studies (including preventive archaeological research) and technical expertise. In this paper, some of these issues will be discussed in detail.
*Corresponding Author