Elena Ristea

The Black Sea is a semi-enclosed basin that has experienced significant environmental degradation driven by nutrient enrichment and pollution from insufficiently treated wastewater discharges. While previous reviews have focused primarily on ecological impacts and eutrophication dynamics, no bibliometric study has systematically examined the representation of wastewater treatment technologies within this literature. This review addresses that gap, providing the first bibliometric synthesis to jointly analyse environmental research trends and wastewater treatment technology development in the Black Sea basin. A total of 1002 peer-reviewed publications indexed in the Web of Science Core Collection between January 2000 and March 2026 were analysed using a Preferred Reporting Items for Systematic Reviews and Meta-Analyses-based framework to examine research trends, thematic clusters, and geographic distribution. A targeted subset of 101 publications directly addressing wastewater treatment technologies was extracted for detailed technological classification. The results reveal a clear increase in research output over the past two decades, with eutrophication, nutrient enrichment, and water-quality degradation as dominant themes. Geographic analysis shows that Türkiye (n = 383), Russia (n = 232), and Romania (n = 129) are the leading contributors, with riparian countries accounting for 83.8% of publications. However, only 101 of the 1002 publications (10.1%) directly address wastewater treatment technologies, with most studies focused on conventional WWTP infrastructure (75.2%) and biological nutrient removal (22.8%). Advanced treatment technologies and nature-based solutions each represent only 3.0% of the wastewater subset. These findings are consistent with a meaningful gap in the regional evidence base for technological approaches to reducing nutrient inputs to the Black Sea, though it should be noted that publication volume alone cannot fully characterise the state of technological development in the region, as it is also shaped by funding structures, disciplinary traditions, and indexing practices. Nevertheless, expanding research on innovative and sustainable wastewater treatment technologies could play an important role in improving wastewater management and supporting long-term ecosystem recovery.

Climate change is modifying the physical structure and biogeochemical functioning of stratified marine systems, with important consequences for trace element (TE) transport, speciation, and exposure. The Black Sea provides a structurally amplified case because restricted exchange, persistent stratification, a basin-scale redoxcline, and extensive shelf-sediment reservoirs intensify climate–contaminant interactions. This review synthesizes mechanistic evidence to develop a climate-informed interpretive framework for TE redistribution under non-stationary environmental forcing. We examine how warming, deoxygenation, hydrological variability, sediment resuspension, acidification, and episodic events alter TE partitioning across dissolved, particulate, sedimentary, and biotic compartments. The synthesis identifies six major redistribution pathways involving surface-layer retention, river plume and suspended particulate transport, shelf-sediment remobilization, redoxcline dynamics, acidification–ligand effects, and event-driven exposure pulses. Together, these processes show that TE patterns increasingly reflect state-dependent internal redistribution rather than external loading alone. To address this shift, we propose a monitoring and risk-interpretation framework that links climate-sensitive state variables to redistribution pathways, integrates multiple matrices, and supports adaptive assessment through trigger-based monitoring escalation. The Black Sea is treated as a structurally amplified reference system for examining climate-sensitive redistribution pathways in stratified basins, although their expression and relative importance remain dependent on basin-specific structural controls.

Synthetic or plastic microfibers (MFs) are an emerging form of microplastic pollution in marine ecosystems, derived from textile degradation and weathering of fishing and aquaculture gear. Despite extensive evidence of MFs in marine organisms, the effects of MFs exposure on mussels remain poorly understood. This study investigated the impact of synthetic MFs on the mussel Mytilus galloprovincialis (Lamarck, 1819) over a semi-chronic time scale of 14 days, using MFs produced by grinding a microfiber cloth. Adult mussels were exposed to three MFs treatments: 8, 40, and 100 MFs/L, reflecting current and future scenarios in the Black Sea. Biomarkers assessed included lysosomal membrane stability (LMS), catalase (CAT), glutathione-S-transferase (GST), and acetylcholinesterase (AChE) activities. Significant lysosomal membrane destabilization (p < 0.05) occurred across all treatments. CAT activity in the digestive gland significantly decreased by 31.2%, 53.3%, and 62.1% at 8, 40, and 100 MFs/L, respectively. GST activity showed inhibition at 8 and 100 MFs/L and stimulation at 40 MFs/L. AChE activity decreased at 8 MFs/L but increased at higher concentrations. These results indicate that even environmentally relevant levels of synthetic MFs can alter cellular stability and enzymatic responses in mussels, suggesting potential ecological risks for marine bivalves.

Eutrophication remains a persistent challenge in the Romanian Black Sea coastal zone, driven by excess nutrient inputs from riverine and coastal sources and further intensified by climate change. This study assesses eutrophication dynamics and explores mitigation options using an integrated framework that combines in situ observations, satellite-derived chlorophyll a data, machine learning, and system dynamics modelling. Water samples collected during two field campaigns (2023–2024) were analyzed for nutrient concentrations and linked with chlorophyll a products from the Copernicus Marine Service. Random Forest analysis identified dissolved inorganic nitrogen, phosphate, salinity, and temperature as the most influential predictors of chlorophyll a distribution. A system dynamics model was subsequently used to explore relative ecosystem responses under multiple management scenarios, including nutrient reduction, enhanced zooplankton grazing, and combined interventions. Scenario-based simulations indicate that nutrient reduction alone produces a moderate decrease in chlorophyll a (45% relative to baseline conditions), while restoration of grazing pressure yields a comparable response. The strongest reduction is achieved under the combined scenario, which integrates nutrient reduction with biological control and lowers normalized chlorophyll a levels by approximately two thirds (71%) relative to baseline. In contrast, a bloom-favourable scenario results in a several-fold increase in chlorophyll a of 160%. Spatial analysis highlights persistent eutrophication hotspots near the Danube mouths and urban discharge areas. These results demonstrate that integrated strategies combining nutrient source control with ecological restoration are substantially more effective than single-measure interventions. The proposed framework provides a scenario-based decision-support tool for ecosystem-based management and supports progress toward achieving Good Environmental Status under the Marine Strategy Framework Directive.

Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which includes oxidative stress, modulation of antioxidant responses, activation of detoxification systems, DNA damage, inflammation, apoptosis, neuroendocrine disruption, and ultimately, cellular energy imbalance. In addition to established pathways, the review highlights recent advances in mechanistic understanding and biomarker development, including cellular stress responses, epigenetic regulation, metal homeostasis mechanisms, and novel molecular indicators. These mechanisms support the development of an integrated biomarker framework that combines classical indicators (e.g., antioxidant enzymes, metallothionein) with next-generation endpoints (e.g., miRNA profiles, gene-level responses of metal transporters or stress chaperones, epigenetic alterations). The interpretation of biomarker responses requires consideration of the exposure context, environmental variables, and physiological status to ensure accurate assessment of sublethal toxicity in field settings. By bridging mechanistic understanding with biomonitoring relevance, this review provides a comprehensive foundation for advancing molecular tools in pollution monitoring and risk assessment. Special emphasis is placed on biomarkers specific to heavy metal exposure, enhancing their diagnostic value relative to general stress indicators.

The study investigates the organochlorinated pesticides (OPCs) content in eight medicinal plant species (Achillea millefolium, Artemisia absinthum , Hypericum perforatum , Tilia sp., Matricaria chamomilla , Taraxacum officinale, Calendula officinalis, Crataegus monogyna), purchased from pharmacies, as well as in infusions prepared from these plants. A total number of 24 samples were analyzed by gas chromatography—electron capture detector (GC-ECD). The transfer rate of OPCs from dried herbs to infusions, as well as the health risk of OPCs residues in infusions (estimated daily intake (EDI) and Hazard Index (HI) were calculated. All medicinal plants (MPs) contained pesticides in different concentrations. For the compounds Heptachlor, p,p' DDT, p,p' DDD, Aldrin, Dieldrin, concentrations well above the maximum residue limits (MRLs) were obtained. The transfer rate of organochlorine pesticides from dried plant to infusion ranged from 3.95% for Heptachlor (Artemisia absinthium) to 57.71% for Dieldrin (Achillea millefolium). The correlation between the OCPs content in the MPs and their infusion are statistically analyzed using the t-test for independence in high dimension, based on the correlation distance. Significant result was found for all OCP detected in the two media, with the content in the MPs significantly correlated with the content in the infusion. The EDI of the detected pesticides was lower than the Acceptable Daily Intake (ADI), and the Hazard Index values were less than 1 (HI < 1) in all infusions. Also, the cumulative hazard index (CHI), showed values less than 1 (CHI < 1) for all types of tea. These results indicate that residues of OCPs in the analysed infusions pose minimal risk to human health. However, taking into account the large transfer variations obtained, the results of the study recommend the development of control protocols for herbal infusions intended for human therapy that include the measurement of OCPs concentrations.

This study assesses the spatial distribution and contamination levels of some heavy metals (HMs), i.e., cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and lead (Pb), in seawater and surface sediments along the Romanian Black Sea coast (RBSC). Sampling was conducted at 40 stations across 12 transects during May–June 2021, and the measured levels of HM concentrations were compared with Environmental Quality Standards (EQS), i.e., maximum allowable concentration (MAC) values, for seawater and effects range-low (ERL) thresholds for sediments. HM concentrations were measured using high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). In seawater, the levels of Cd, Cu, and Pb concentrations exceeded the MAC values at three stations located in areas influenced by the Danube River or anthropogenic activities. In sediments, exceedances of ERL thresholds were found for Ni at 11 stations, for Cu at three stations, and for Pb at one station. HM contamination of sediment samples collected from these stations can be caused by both natural and anthropogenic sources, e.g., the Danube River, rock/soil weathering and erosion, agricultural runoff, port and construction activities, maritime and road transport, coastal tourism, petrochemical industry, wastewater discharges, offshore oil and gas extraction. Principal Component Analysis (PCA) provided valuable information about the relationships between relevant variables, including water depth and HM concentrations in seawater and sediments, and potential sources of contamination. The results highlight the influence of fluvial inputs and localized human activities on HM contamination. While the overall chemical status of Romanian Black Sea waters and sediments remains favorable, targeted management strategies are needed to address localized pollution hotspots and mitigate potential ecological risks. These findings provide valuable insights for environmental monitoring and sustainable coastal management.

This study investigates the long-term seasonal shifts in nutrient dynamics and eutrophication processes in the Romanian Black Sea coastal waters using multi-decadal data (1960/1976/1980–2023). The findings highlight significant seasonal and interannual changes, revealing a progressive rise in seawater temperature, declining oxygen concentrations, and notable shifts in nutrient stoichiometry, particularly an increasing nitrogen–phosphorus (N:P) ratio. These changes are closely associated with increased occurrences of harmful algal blooms (Noctiluca scintillans), emphasizing the complex relationship between warming, nutrient and dissolved oxygen cycles, and biological activity. Seasonal patterns show that prolonged warmer periods, especially during autumn, exacerbate oxygen depletion and nutrient imbalances, with implications for marine life and food webs. The study underscores the importance of targeted nitrogen reduction strategies, including optimized fertilizer use, improved wastewater treatment, and the establishment of buffer zones to minimize land-based nutrient inputs. Regional cooperation and integrated coastal management aligned with the Marine Strategy Framework Directive are essential for mitigating eutrophication. The results provide critical insights into the impacts of climate change on the Black Sea ecosystems. This research contributes to global efforts under SDG 13 (Climate Action), SDG 14 (Life Below Water), and SDG 3 (Good Health and Well-being), addressing the key challenges to marine biodiversity, water quality, and ecosystem sustainability.

The purpose of this paper is to determine the level of polycyclic aromatic hydrocarbons (PAHs) from medicinal plants and infusions prepared using them, as well as assess the transfer of these contaminants from plants to infusions. The separation of compounds was achieved using microwave extraction for dried plants and liquid–liquid extraction in the case of infusions. The extracts were cleaned using solid-phase extraction, and the compounds were analysed using gas chromatography coupled with mass spectrometry (GC-MS). Exposure to PAHs through tea infusion consumption was evaluated by calculating the estimated daily intake (EDI, ng/kg.bw/day) and Margin of Exposure (MOE). The average total content of PAHs varied from 277.22 ± 12.78 to 2466.46 ± 203.45 µg/kg in dry plants, and the compounds benzo[b]fluoranthene (BbF) and benzo[a]pyrene (BaP) were present in all samples. In the herbal tea infusions, the average total PAH content varied between 612.55 ± 46.12 ng/L and 2292.2 ± 140.24 ng/L. The observation was statistically checked using a two-sample paired test. The analysis revealed that PAHs could be split into those for which the content in the medicinal plants is significantly larger than in the infusions and those for which the difference is not significant. The average transfer rates of ∑16PAHs from plants to infusions varied from 7.25 to 32.86%. The MOE values confirmed that consumer exposure to PAHs via tea infusions is very low and safe for health.

This study provides a comprehensive evaluation of contamination levels in the Romanian Black Sea within the framework of the Marine Strategy Framework Directive (MSFD). Over the course of five oceanographic expeditions between 2020 and 2022, data were gathered from 70 stations in transitional, coastal, shelf, and offshore waters of the Black Sea. Analyses were conducted on water, sediment, and biota samples for key contaminants: heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) such as organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs). The assessment identified contamination hotspots near riverine inputs, urban runoff, harbor activities, and industrial discharges. Offshore waters also showed measurable pollutant levels, likely from diffuse sources and atmospheric deposition. The key findings reveal the widespread contamination of HMs, PAHs, and POPs across the Romanian Black Sea, with concentrations in certain areas exceeding acceptable environmental thresholds, highlighting ongoing challenges for regional pollution management. PAHs were prevalent in both nearshore and offshore regions, while OCPs and PCBs were detected across various matrices, with significant concentrations observed in water and biota samples. The study emphasizes the importance of integrated assessments within the MSFD framework, suggesting that future evaluations should complement the “one out-all out” (OOAO) approach with multi-metric tools, to enhance the robustness of pollution status reporting. Despite improvements in some areas, contamination remains a critical challenge, requiring strengthened regulations, improved waste management, and increased regional cooperation to mitigate the ongoing risks to marine ecosystems. The findings provide valuable data for the upcoming national MSFD assessment cycle (2018–2023) and highlight the need for sustained monitoring and coordinated efforts to ensure long-term marine sustainability.