SE Romania Research Articles

Nesting ecology and confirmed breeding of the invasive pond slider Trachemys scripta in an urban environment, Romania

The pond slider (Trachemys scripta) is a major invasive species in freshwater habitats across the world. For decades, the main cause of individuals’ occurrences in the wild was the illegal release of pet animals. Recently, as an important component of their management, there has been an increasing focus on their ability to successfully reproduce in the invaded regions. In Romania, the species is reported as widespread in urban wetland environments within major cities, but information about its nesting and potential breeding remains scarce or anecdotal. We surveyed a large population of pond sliders in an artificial urban wetland site in Constanţa, SE Romania, and described their nesting ecology and reproductive output. Although eggs from several nests failed to hatch or were predated, potentially limiting their reproductive success, sliders were found to breed successfully at this site, with 18.6% viable hatchlings recorded. Our study could serve as a baseline for additional targeted surveys and to inform decision-making for successfully managing this invasive species. Although the importation, trading, and breeding of this species are prohibited by EU legislation, active and effective management is now required to address the successful reproduction and further potential spread of T. scripta.

Metals and Natural Radioactivity Investigation of Danube River Water in the Lower Sector

In this paper high-resolution continuum source atomic absorption spectrometry (HRCS AAS) was used for the determination of metal concentrations in Danube water collected in the river lower sector in SE Romania (Braila-Galati-Tulcea). The evaluation of the water natural radioactivity was only performed in Galati sector based on selected radiological parameters: gross alpha/beta activity and radionuclides (210Po, 210Pb, natU, natTh and 226Ra) activity concentrations. The results indicate a temporal and spatial variability of contaminant levels due to anthropogenic inputs and seasonal conditions. For several heavy metals, the registered concentrations exceed the legislated values, imposing a regular monitoring of water quality especially in the case of using the water resource for human consumption, irrigation or aquaculture.

Dasycladalean algae from Middle-Upper Triassic limestones of North Dobrogea (SE Romania)

The Triassic carbonate deposits are widely distributed in North Dobrogea (SE Romania) mainly within the Tulcea Nappe. Within this structural unit, the carbonate facies reveals an eastward-westward transition from shallow-water to basin facies. The shallow-water limestones were studied in three areas (Murighiol-Dealul Duna, Dunavatu de Sus and Enisala) in order to identify and describe the algal flora. In this paper we describe the assemblage of dasycladalean green algae. Thirteen species were identifi ed, out of which nine are also known from other parts of the Alpine-Carpathian or Dinaric areas (Macroporella alpina, Poncetella hexaster, Neophysoporella lotharingica, Ardeiporella cf. karrerioidea, Poikiloporella duplicata, Probolocuspis cf. hydrae, Salpingoporella sturi, S. cf. triasica and Clypeina besici). Three species are new (Pseudodiplopora ioanaletitiae n. sp., Julpiaella baltresi n. sp. and Acicularia claudiopolitana n. sp.) and one species (Ioanella dobrogiaca) was already the subject of a previous work. This is the richest assemblage of calcareous dasycladalean algae described so far from the Triassic of Dobrogea. In addition, the Clypeina besici-Poikiloporella duplicata association is also important for age constraints because it is characteristic for the Carnian stage.

New insight into the organogenus Ioanella Granier & Berthou, 2002, with description of Ioanella dobrogiaca organosp. nov. from Triassic limestones of the Dobrogea (Romania)

ABSTRACT Triassic deposits are widespread in the Măcin Unit of Northern Dobrogea (SE Romania). At the Enisala Fortress hill, near the village of Enisala, they are predominantly represented by grey bioclastic limestones of Wetterstein-type facies of the latest Ladinian to Carnian age. Samples collected from the lower part of this unit, i.e. from strata cropping out on the right side of the road from Sarichioi to Enisala, yield an association of calcareous algae, among which one is described in this paper as a new representative of the organogenus Ioanella. Ioanella dobrogiaca organospecies nov. differs from the type-species of the genus, Ioanella lusitanica, by its morphological and dimensional characteristics. Its features allow us to refine the diagnosis of the organogenus Ioanella. Additionally, comparisons with other dasycladalean organogenera demonstrate that Ioanella is a discrete genus.

Characterization of soils around a former chemical plant in Braila, SE Romania, using high performance atomic techniques (EDXRF, AAS, ICP-MS)

This paper presents the problem of soil pollution in the vicinity of a former chemical plant, given that production activity was stopped for more than thirty years ago. The old chemical plant was located in the southern part of Braila town, SE Romania, just a few kilometers from the left bank of the Danube River. Prior to 1990, there was a significant production of industrial chemical goods, such as sulfuric acid, carbon dioxide for synthetic fibers, chlorine gas and hydrochloric acid obtained by electrolysis processes with mercury electrodes and heavy metal catalysts (Cd, Ni, Zn), sodium sulfide and sulphate, etc. For the good development of the experimental program, a number of 10 soil samples were collected from the north, northwest, west, southwest and south of the former chemical plant. The multi-element analysis method used to determine the trace elements in the soil samples was energy-dispersive X-ray fluorescence spectrometry (EDXRF), using a Genius XRF portable spectrometer manufactured by Skyray Instruments Inc., equipped with a large surface Si with a Be window and a 40 kV/100 µA miniature X-ray tube excitation source with Ag target. The spectrometric system has an energy resolution up to 139 eV, and the detection limits of the order of ppm. A total of 21 chemical elements were identified in the target soil samples, such as: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Hg, Rb, Sr, Y, Zr, Nb, Mo, Sn, Sb, Pb. The compositional analyses of contaminated industrial soils were completed by using the AAS and ICP-MS high performance and selectivity techniques.

ATR-FTIR analysis of filter paper with mass addition of seaweed Ulva Rigida C. Agardh

This paper presents the results obtained from the analysis of some filter paper samples using Fourier Transform Infrared Spectroscopy (FTIR) technique. Based on the FTIR capabilities, using the infrared light to scan the samples and identify their chemical properties, organic, polymeric and inorganic materials can be characterized. The samples analysed were six filter papers with different mass additions of Ulva Rigida C. Agardh seaweed collected from the Black Sea, in Constanta area, SE Romania. The additions used consisted of 0.5%, 1%, 2%, 4% and 8% seaweed material, grounded to a certain grain size.

Hiding in plain sight: Integrative analyses uncover a cryptic Salvia species in Europe

AbstractSalvia is the most species‐rich genus of the family Lamiaceae, currently numbering almost 1000 species. The diagnostic feature of the genus is the unique staminal lever mechanism that allows for specific pollination modes. We encountered an unusual Salvia form in the field, in SE Romania, which resembles S. austriaca but features a radically different lever mechanism. This form proved to be geographically widespread on the Pontic steppe, never occurring in sympatry with S. austriaca. We used an integrative approach, employing morphometric and phylogenomic (RADseq) analyses, to study this unusual form. The taxon's floral morphology proved to be consistently and subtly different from that of S. austriaca, and similarly, Bayesian species delimitation using genome‐wide SNP data indicated species‐level differences. Our results provide compelling evidence that points toward the discovery of an unrecognized species. This species has been overlooked for centuries, misidentified as S. austriaca, a closely related taxon. The new species differs from S. austriaca in key features of floral structure, habitat preference, and distribution. The potential range of this cryptic species, its pollination biology, ecology, and phylogeography are discussed.

Competition-cooperation in the chemoautotrophic ecosystem of Movile Cave: first metagenomic approach on sediments

BackgroundMovile Cave (SE Romania) is a chemoautotrophically-based ecosystem fed by hydrogen sulfide-rich groundwater serving as a primary energy source analogous to the deep-sea hydrothermal ecosystems. Our current understanding of Movile Cave microbiology has been confined to the sulfidic water and its proximity, as most studies focused on the water-floating microbial mat and planktonic accumulations likely acting as the primary production powerhouse of this unique subterranean ecosystem. By employing comprehensive genomic-resolved metagenomics, we questioned the spatial variation, chemoautotrophic abilities, ecological interactions and trophic roles of Movile Cave’s microbiome thriving beyond the sulfidic-rich water.ResultsA customized bioinformatics pipeline led to the recovery of 106 high-quality metagenome-assembled genomes from 7 cave sediment metagenomes. Assemblies’ taxonomy spanned 19 bacterial and three archaeal phyla with Acidobacteriota, Chloroflexota, Proteobacteria, Planctomycetota, Ca. Patescibacteria, Thermoproteota, Methylomirabilota, and Ca. Zixibacteria as prevalent phyla. Functional gene analyses predicted the presence of CO2 fixation, methanotrophy, sulfur and ammonia oxidation in the explored sediments. Species Metabolic Coupling Analysis of metagenome-scale metabolic models revealed the highest competition-cooperation interactions in the sediments collected away from the water. Simulated metabolic interactions indicated autotrophs and methanotrophs as major donors of metabolites in the sediment communities. Cross-feeding dependencies were assumed only towards 'currency' molecules and inorganic compounds (O2, PO43−, H+, Fe2+, Cu2+) in the water proximity sediment, whereas hydrogen sulfide and methanol were assumedly traded exclusively among distant gallery communities.ConclusionsThese findings suggest that the primary production potential of Movile Cave expands way beyond its hydrothermal waters, enhancing our understanding of the functioning and ecological interactions within chemolithoautotrophically-based subterranean ecosystems.

The unique topography from Obanul Mare (Mangalia, SE Romania): remnant of a maze cave

The area around the town of Mangalia in Southern Dobrogea (Romania) hosts a unique karst landscape represented mostly by large collapse dolines. Around one of these collapse dolines, named Obanul Mare, there is a peculiar morphology of hillocks that resemble the tropical labyrinth-cone karst but on a much-reduced scale. This peculiar relief was hypothesized to be residual, resulting from the ceiling collapse of a two-dimensional maze cave. This type of maze caves form when the water table remains stable for long periods of time, allowing groundwater to dissolve the carbonate host rock along all available discontinuities. The Obanul Mare structure contains a 200 m long cave (Movile cave), whereas a few kilometers away we can find Limanu maze cave, whose passages sum up to more than 3,500 m. Because the existence of a former maze cave is difficult to demonstrate, in this study we took an indirect approach to this issue. We hypothesize that if there was a maze cave and its ceiling collapsed, then the inner walls would be left standing as pillars. Subsequent subaerial evolution of these pillars would create slopes that would incline towards the former cave passages. By quantifying the slope aspect from a high-resolution digital surface model, we would be able to identify the direction of the original passages, hence the main hypothetical fracture lines along which those passages formed. By comparing these orientations to those of local fractures (deduced from the nearby valley and doline axes), as well as with the orientations of the Movile Cave passages, we found that they are well correlated. This strengthens the hypothesis that the hillocky terrain is tectonically conditioned and that it might be the result of cave ceiling collapse, bringing more information on the existence of maze caves in the region.

Comprehensive mineralogical and physicochemical characterization of recent sapropels from Romanian saline lakes for potential use in pelotherapy

In this study we aimed to compare the mineralogical, thermal, physicochemical, and biological characteristics of recent organic carbon-rich sediments (‘sapropels’) from three geographically distant Romanian lakes (Tekirghiol and Amara, SE Romania, and Ursu, Central Romania) with distinct hydrogeochemical origins, presently used for pelotherapy. The investigated lakes were classified as inland brackish Na-Cl-sulfated type (Amara), coastal moderately saline and inland hypersaline Na-Cl types (Tekirghiol and Ursu, respectively). The settled organic matter is largely composed of photosynthetic pigments derived from autochthonous phytoplankton. Kerogen was identified in the sapropel of coastal Tekirghiol Lake suggesting its incipient maturation stage. The mineral composition was fairly similar in all sapropels and mainly consisted of quartz, calcite, and aragonite. Smectite, illite, mixed layer smectite/illite appeared as major clay components. Potentially toxic elements were found in low concentrations. The physical properties (i.e., specific heat, thermal conductivity and retentivity) and cation exchange capacity are comparable to other peloids used for therapy. This study is the first comprehensive multi-approached investigation of the geochemical nature of recent sapropels in Romanian saline lakes and thus contributes to expanding our knowledge on the origin and physicochemical qualities of organic matter-rich peloids with therapeutic uses.

Local-scale impact of wind energy farms on rare, endemic, and threatened plant species

BackgroundWind energy farms have become a popular solution to produce green energy worldwide. Their development within protected areas has increased dramatically in the past decade, and the effects on the rare, endemic and threatened plant species (i.e., protected plant species), essential for habitat conservation and management, are little known. Only a few studies directly quantify the impacts of wind energy farms on them. Our study analyzes the impact of wind energy farms on rare, endemic, and threatened plant species in steppic habitats and their recovery potential over a ten-year period on a wind energy farm within the Dealurile Agighiolului Natura 2000 site (Dobrogea Region, SE Romania).MethodsWe surveyed the rare, endemic, and threatened plant species within a radius of approximately 50 m around each of the 17 wind towers during the wind farm operational phase. We selected 34 plots to allow the investigation of two types of areas: (1) a disturbed area overlapping the technological platform, where the vegetation was removed before construction, and (2) an adjacent undisturbed area. To understand the effects of the wind energy farm on the rare, endemic, and threatened plant species diversity and the differences between the disturbed and undisturbed areas, we calculated under both conditions: (1) plant species richness; (2) sample-size-based rarefaction and extrapolation with Hill numbers parameterized by species richness; (3) non-metric multidimensional scaling of Jaccard dissimilarity index; (4) functional diversity; (5) beta-diversity (including replacement and nestedness of species).ResultsAs a result of the disturbances caused by the wind energy farm’s development, we identified a sharp contrast between the diversity of rare, endemic, and threatened plants inhabiting disturbed and undisturbed areas near the wind towers. Our research showed that less than 40% of the total inventoried rare, endemic, and threatened species colonized the disturbed sites. Species turnover within undisturbed plots was higher than disturbed plots, implying that the plant community’s heterogeneity was high. However, a higher richness in rare, endemic, and threatened plant species was found in the plots around the wind towers in grasslands of primary type. Sample-size-based rarefaction and extrapolation with Hill numbers by observed species richness indicated an accurate estimation of species richness in disturbed habitats, demonstrating that recovery after wind energy farm construction was incomplete after ten years of low-intensity plant restoration and conservation activities. Thus, we consider that operating activities must be reconfigured to allow the complete recovery of the communities with rare, endemic, and threatened plant species.

Zooarchaeological analysis of the faunal remains from the Palaeolithic site of La Adam Cave (Dobrogea, SE Romania) – new data from recent excavations

Săpăturile arheologice efectuate recent (2006– 2009) în situl paleolitic din Peștera La Adam (Dobrogea Centrală, sud-estul României) au furnizat numeroase resturi fosile, care au fost analizate în scopul obținerii mai multor informații asupra asociației faunistice din Pleistocenul târziu în zona peșterii, asupra contribuțiilor animalelor și omului la acumularea oaselor în interiorul peșterii, și asupra proceselor tafonomice prezente în sit. Resturile faunistice analizate au fost foarte fragmentare, fapt care nu a permis, în cazul celor mai multe, o determinare taxonomică mai precisă. Totuși, numeroase specimene prezintă urme de coroziune chimică și semne ale mușcăturilor unor carnivore, doar câteva prezentând semne de activitate antropică. Peștera pare să fi funcționat în special ca adăpost pentru carnivore, resturile ursului de peșteră dominând numeric. Alte carnivore mari, cum ar fi hienele de peșteră, au contribuit de asemenea, cel mai probabil, la acumularea oaselor, rumegătoarele de dimensiuni mari și medii reprezentând cel mai frecvent prada acestora.

A new Late Bronze Age sceptre-pestle discovered at Limanu, Constanța County (SE Romania)

Late Bronze Age stone sceptres/pestles are a category of artefacts enjoying a certain distinction, found across a vast area, from the western Black Sea to Central Asia. On this instance, we publish one such object discovered in Limanu, Constanta County (south-eastern Romania), which can be attributed to type II according to the typology established by Nikolaus Boroffka and Eugen Sava. Such sceptres/pestles are mostly made of local rock and can be assigned to the Noua-Sabatinovka-Coslogeni cultures. The low wear and tear of the pieces indicates usage. This may imply that the objects stopped being used shortly after their allocation or that they were used for ceremonial purposes for a short period.

A study on drinking water quality in SE Romania

Water is a fundamental and indispensable constituent of the human body. Small changes produce serious disorders and insufficient water intake is much less tolerated than in other deficiency. The aim of this work is the study of drinking water quality indicators in selected localities in SE Romania (Galati, Braila, Buzau, and Vrancea counties). Water samples were taken from sources of drinking water (tap water, well water, spring water, filtered tap water with biological filter), frequently used by the population (15 places). They were subjected to chemical and physico-chemical analysis in order to determine the physical, chemical parameters of quality that can have impact on the health of residents. In five water sources (Independenta (tap), Independenta (spring), Lunca/Buzau, Liesti fountain at 40 m depth and Galati (biologically filtered tap water) the pH is below 6.5, a value that does not fit into STAS acquis in force - SR ISO 10523-2009. Oxidability index values in the majority of cases are below the maximum allowed, of 5 mg O2/L water, according to SR EN ISO 8467-2001; in some cases, the values exceed the limits as following: Independenta: 8 mg O2/L; Lunca/Buzau: 10 mg O2/L; Focsani spring: 9 mg O2/L; Focsani tap: 8 mg O2/L; Galati tap: 6 mg O2/L.

ATR-FTIR qualitative mineralogical analysis of playground soils from Galati city, SE Romania

Soil has an important influence on human health, especially for children, due to more frequent dermal contact, ingestion and inhalation. Urban playgrounds are of particular concern, because of the presence of a multitude of dust particles of natural or anthropogenic origin, which could enter or interact with the toddlers’ body. In this work, the soil samples were collected from important playgrounds from Galati city, Romania, being subjected to a mineralogical investigation by Total Attenuated Reflectance Fourier Transform Infrared Spectrometry (ATRFTIR) technique using a BRUKER TENSOR 27 FTIR spectrometer coupled with a diamond ATR device. Preliminary results of ATR-FTIR analyses of the soil samples highlighted the presence of montmorillonite, kaolinite, quartz and calcite as soil mineralogical constituents. The main aim of this paper was to observe if the characteristic peak of Chrysotile, a component of asbestos, can be identified in the spectra of the investigatedtarget urban soils from playgrounds.

Physical and Hydro-Physical Characteristics of Soil in the Context of Climate Change. A Case Study in Danube River Basin, SE Romania

The intensification of climate change has led to the degradation of thousands of arable lands through desertification and extreme weather events. The Danube River basin in the Galati-Braila region, SE Romania, is a transboundary area of community and international importance, increasingly affected by drought, water, and wind erosion. Consequently, the aim of this study is to evaluate the main physical and hydro-physical parameters of soils, implied in water storage and with a defining role in erosion intensity, nutrients and toxicants cycle and availability, and crops yield. Soil samples were collected both in the disturbed and undisturbed state, from Smardan, Sendreni, and Vadeni agricultural lands and riparian areas of semiaquatic ecosystems, located in the vicinity of the steel platform of the Galati industrial area. Specific laboratory methods of investigation and formulas were used. Chernozems (CZ), Fluvisols (AS), and Gleysols (GS) of different subtypes and various physico-chemical parameters were identified. The results suggested that CZ are of coarse and medium texture, while AS and GS are medium–fine and fine textured. In correlation with this, bulk density values range from extremely low–low to low–high classes. In relation to soil physical parameters and the content of organic matter, hydro-physical indices show water supply imbalances. Through the approached theme, the study is of practical importance for sustainable management of the soil, agricultural projects, and landscaping. This study provides government authorities and non-governmental organizations an overview of the local and regional soil conditions, so that new measures can be regulated to protect it against irrational use.

Soil spatial patterns analysis at the ancient city of Ibida (Dobrogea, SE Romania), via portable X-ray fluorescence spectrometry and multivariate statistical methods

In this study we investigated the potential usefulness of multi-elemental soil analysis, obtained by a portable XRF spectrometer, to recognize ancient anthropogenic features, compared to the natural context on the territory of Roman-Byzantine Ibida city (Dobrogea, SE Romania). Soil samples were collected from 16 soil profiles and 2 archaeological excavations, from each soil horizon and cultural layer. Pearson correlation matrix of topsoil elements showed significant correlations among the various geogenic elements such as Ti, Fe, Mn, Zr, Ba and Cr. In the case of P, a strong correlation was found with Ca, a lower correlation with K, and no significant correlation with the other elements. Also, Cu and Zn behave differently, showing no significant correlation with any of the elements. Principal components analysis (PCA) and agglomerative hierarchical clustering (AHC) were carried out in order to identify groups of inter-correlated variables and assess the degree of association among soil profiles. The correlation between soil elements and the principal components suggest the presence of three groups which were defined as the geogenic, archaeo-anthropogenic and agro-anthropogenic component. Spatial distribution of topsoil elements was mapped by geostatistical methods in order to see if their spatial patterns reveal the influence of human activities. Although the results show that certain elements such as Ca, P and K present higher concentrations in the Ibida fortress area, we found that the interpretation of multi-elemental composition of the topsoil only is not sufficient for an accurate identification of the ancient characteristics which can be linked to the Roman-Byzantine period. Hence, we wanted to know if the presence of archaeological sites could be revealed by higher variation degree of soil elemental data along the profile depth. Therefore, we tested the utility of a synthetic statistical index, namely the variation coefficient, which was computed for each soil profile using all the available data. The results showed that if the index was standardized according to profile depth, then it became a useful indicator for the presence of ancient human activities.

Integrated biostratigraphic, palaeoenvironmental and wireline log characterisation of upper Miocene to lower Pliocene successions of the eastern Dacian Basin (SE Romania)

Integrated biostratigraphic, palaeoenvironmental and wireline log characterisation of upper Miocene to lower Pliocene successions of the eastern Dacian Basin (SE Romania)

Palaeovegetation and palaeoclimate evolution during the Late Miocene to Early Pliocene of SE Romania

Fossil microfloral assemblages from five sedimentary successions of the Dacian Basin (Eastern Paratethys) are used to reconstruct the palaeovegetation and palaeoclimate of SE Romania during the Late Miocene to Early Pliocene (regional stages Khersonian, Meotian, Pontian, and Dacian). The studied microfloras were deposited under brackish to freshwater conditions in a fairly distal area of the Dacian Basin and are interpreted to reflect changes in the terrestrial ecosystems at a regional scale. The results show that the vegetation dynamic of the area was driven by the interplay of palaeogeographical and climatic changes. Broadleaved deciduous trees characteristic of temperate climatic regimes and a variety of gymnosperms dominated the vegetation during the Khersonian and the Meotian. This type of vegetation underwent a gradual decline throughout the studied time span, probably associated with a long‐term cooling and drying trend. Thermophilous taxa were virtually absent in the area, with the exception of Engelhardia and Taxodioideae, which probably inhabited lowland swamp forests. The effect of an arid phase, which had its acme during the late Khersonian and extended, in an attenuated mode, during the earliest Meotian, is reflected in the palynological assemblages. This event resulted in the development of a xeric flora including Ephedra and Lygeum. The latter genus is cited for the first time in the Neogene flora of the Eastern Paratethys. Although mesic herbaceous taxa generally occur in low numbers throughout the successions, its signal becomes more relevant in the Pontian, suggesting drier conditions favourable for open ecosystems to develop. During the Dacian substage, the transition from brackish to freshwater settings in the basin favoured the development of shallow, freshwater marshes and led to the spread of a diverse hygrophytic flora. At the same time, a significant increase in Celtis pollen is interpreted to represent increased seasonality of precipitation.

Luminescence chronology of the northeastern Bulgarian loess-paleosol sequences (Viatovo and Kaolinovo)

The key reference loess sequence of Viatovo in NE Bulgaria, lying within the lower Danube basin, records climatic and environmental changes over the last 800 ka. This 20 m thick loess sequence consists of seven loess units (L1 to L7) intercalated by six paleosols (S1 to S6) below the modern soil (S0). The Matuyama-Brunhes palaeomagnetic boundary has been identified in the lowest loess unit (L7). This reference loess sequence remains so far undated by radiometric techniques. Its chronostratigraphy relies only on pedostratigraphic and magnetostratigraphic evidence. This contrasts with the adjacent reference loess sequences of SE Romania (Tuzla, Mostistea, Mircea Vodă) whose luminescence chronology is now securely established up to MIS 8.The aim of this study is to validate the chronostratigraphic framework of the Viatovo loess sequence using the luminescence dating method. For this purpose, the luminescence method is applied to the three upper loess units (L1, L2, L3) from two adjacent sites: the reference site of Viatovo and the nearby site of Kaolinovo, both located in the Ludogorie region (NE Bulgaria) and showing the same superposition of loess (L1 to L7) and interbedded paleosols. Luminescence dating (Infrared stimulated luminescence; IRSL) was carried out using the feldspar fine sand-size grain fraction (60–80 μm), applying the IRSL50 and the pIRIR290 dating techniques. For the equivalent dose (De) determination we used both the SAR post-infrared infrared (pIRIR290) protocol on single aliquots and the multiple-aliquot additive dose (MAAD IRSL50) protocol. The pIRIR290 ages and the fading corrected MAAD-IRSL50 ages are self-consistent. It demonstrates for the first time, that the three upper loess layers (L1, L2, L3) at Viatovo and Kaolinovo were deposited during the marine isotope stages (MIS) 2–4, 6 and 8, thus constraining the youngest well-developed paleosol (S1, a chernozem) to the Last Interglacial. These IRSL50 and pIRIR290 ages are in good agreement with the luminescence ages obtained for (1) the two upper loess layers (L1, L2) from the Harletz sequence in NW Bulgaria and (2) the three upper loess units (L1, L2, L3) from the adjacent SE Romanian loess sequences.The luminescence chronology of the loess sequences is presented along with the pedogenic and magnetic property data. The pedostratigraphic records of the NE Bulgarian and SE Romanian loess sequences show the same palaeoclimatic trends, with progressive aridification during interglacial periods (from S6 to S0).