Sea Coastal Area Research Articles

Origin of biomarkers (PAH, n-alkane, hopane, estrane) in different colors of plastic resin pellets and surface sediments from coastal area of the Makuran-Oman Sea

The unique attributes of the study area, situated near the Strait of Hormuz—an extensively utilized oil shipping corridor for Iran and neighboring Arabian nations—encompass oil extraction and exploitation, the establishment of an oil export hub, the advancement of petrochemical industries, as well as tourism and transportation activities. This research represents the first examination of the sources of plastic resin pellet release, addressing both local and non-local contributions. To conduct this study, samples of plastic resin pellet and coastal and intertidal surface sediments were collected from seven stations on the shores of the Oman Sea in Hormozgan province (Sirik, Garook, Ziarat, Karpan, Koohestak, Gohardo, and Kargan) with four replications to determine the origin and spatial distribution pattern of hydrocarbons and the diffusion source of plastic resin pellets (offshore or regional). Plastic resin pellets were separated based on color (white, yellow, brown, and black). Soxhlet was used to extract hydrocarbons, two stages of column chromatography were used to separate compounds, and gas chromatography–mass spectrometry (GC–MS) was used to identify and determine their concentration. The total n-alkanes concentration ranged from 2940 to 18,711 (μg/g) in coastal surface sediments, from 19,721–1678 (μg/g) in intertidal surface sediments, and from 11,481.50 to 55,601.41 (μg/g) in plastic resin pellets. A similar trend was found for the total PAH concentration which ranged from 135.57 to 3890.62 (ng/g) in coastal sediments, from 1820.28 to 6579.55 (ng/g) in intertidal sediments, and from 3714.19 to 66/1920451 (ng/g) in plastic resin pellets. According to the sediment pollution criteria, a high pollution level was assessed in most of the stations. In most of the surface sediments and plastic resin pellets, the presence of unresolved complex mixture (UCM), the carbon preference index (CPI) lower than 1, and the diagnostic ratios of PAH, hopane, and sterane compounds indicated petrogenic origin for hydrocarbons. The results of principal component analysis based on 16 diagnostic ratios of PAH, n-alkane, hopane, and sterane compounds showed that brown and black plastic resin pellets were placed in a different group than the coastal and intertidal sediments and white and yellow plastic resin pellets. Most likely, the diffusion source of brown and black plastic resin pellets is different and through open water.

Chlorophyll-a Concentrations analysis During COVID-19 Lockdown Period in Northern Egyptian coastal Area of Mediterranean Sea Using Google Earth Engine

Chlorophyll-a Concentrations analysis During COVID-19 Lockdown Period in Northern Egyptian coastal Area of Mediterranean Sea Using Google Earth Engine

Long-time prediction of multi-indicator water quality based on the improved WaveNet under time series decomposition and phase space reconstruction

Abstract Long–time prediction of water quality indicator such as chlorophyll–a (Chl–a) is crucial for water process engineering and environmental management. In order to capture the characteristics of long–time series and reduce the limitations of traditional long–time prediction strategies, this paper proposes a novel hybrid model by combining data decomposition, phase space reconstruction, feature fusion and improved WaveNet. Firstly, the original data is decomposed into several subsequences through time series decomposition. Then, the subsequences with chaotic characteristics are integrated with multiple features for phase space reconstruction. Next, the decomposed and reconstructed subsequences are fed back into the improved WaveNet model separately. Finally, the prediction results are obtained by summing the predicted values of the subsequences. In this paper, the reliability of the method is assessed using the dissolved oxygen, water temperature, pH and Chl–a data of a monitoring station in the Beihai coastal sea area, ablation experiments are conducted to demonstrate the effectiveness of each module in the proposed model, and comparisons with multiple benchmark and hybrid models show that the proposed model exhibits better performance in long–time prediction of coastal water quality in the next fourteen days.

The Problem of Power Variations in Wind Turbines Operating under Variable Wind Speeds over Time and the Need for Wind Energy Storage Systems

One of the most important and efficient sources of green electricity is catching air currents through wind turbine technology. Wind power plants are located in areas where the energy potential of the wind is high but it varies. The time variation of the wind generates fluctuations in the power produced by the wind farms that is injected into the grid. This elevates, depending on the intensity, problems of network stability and the need for balancing energy, thus raising both technical and cost issues. The present paper analyzes the behavior of a wind turbine (WT) over time in varying wind speed conditions, highlighting that without automation algorithms, a WT is far from the operation at the maximum power point (MPP). However, even when it is brought to operate at MPP, there are still significant variations in the power injected into the network. These power variations can be compensated if the wind system has energy storage facilities for the captured wind. All of these assumptions are analyzed using improved mathematical models and processed in simulations, with experimental data used as input from a wind turbine with an installed power of 2.5 [MW] in operation on the Romanian Black Sea coastal area. Consequently, the paper demonstrates that during an operation in the optimal area, from an energy perspective, the wind turbine’s maximum power point requires a storage system for the captured wind energy.

Reproductive biology of the commercial sea cucumber Holothuria (Roweothuria) poli, in the Central Aegean Sea, Greece

Holothuria poli is one of the most in-demand sea cucumber species and has attracted the interest of markets in Mediterranean regions. The present study is the first attempt to determine the reproductive cycle of H. poli in a coastal area of the Central Aegean Sea. Samples of H. poli as well as environmental and biometric data were collected monthly for 1 year. The sample population exhibited a female predominance, a size at first maturation of 156.3 mm and a distinctive reproductive pattern that reached its mature stage in the summer months. These findings contribute to the overall understanding of the reproductive physiology of the species and provide information for the sustainable management of sea cucumber stocks in the Hellenic Seas.

The poly(ADP-ribosyl)ation system in the crustacean copepod Temora stylifera (Dana, 1853–1855) from a coastal area of the Mediterranean Sea: a new biomarker of the health status

The poly(ADP-ribosyl)ation system in the crustacean copepod Temora stylifera (Dana, 1853–1855) from a coastal area of the Mediterranean Sea: a new biomarker of the health status

A Comparative Study on Wind Profiles and Surface Aerodynamic Parameters of Typhoons Over Coastland and Coastal Sea

AbstractUnderstanding the aerodynamic characteristics of landfalling typhoons is of great importance for both wind engineering and meteorology. This study comparatively investigated the near‐surface wind profiles and aerodynamic parameters over coastland and coastal sea areas using typhoon observational data collected by Doppler wind lidars and wind tower anemometers during the passage of 15 typhoons that made landfall over China during 2009–2020. Specifically, the three surface aerodynamic parameters of roughness length, friction velocity, and drag coefficient (Cd) were obtained using the logarithmic law wind profile method. Results showed that the near‐surface wind profiles became much closer to the power law wind profile with increase in wind speed. The values of roughness length and friction velocity over the coastal sea were found to exceed those over coastland areas when the 10‐m wind speed (U(10)) was larger than 18 m s−1. The critical wind speed at which Cd peaks over the coastal sea was found to be 24 m s−1. There are two peaks in the variation of Cd with U(10) under the condition of onshore wind over the sea, which has never been reported in previous observational studies. Finally, a formula for Cd was proposed to describe the variation in Cd with U(10) under the condition of onshore wind over land, which is expected to be applied in the typhoon surface layer scheme to improve numerical simulation of landfalling typhoons.

Conceptual Model for Integrated Meso-Scale Fire Risk Assessment in the Coastal Catchments in Croatia

Various factors influence wildfire probability, including land use/land cover (LULC), fuel types, and their moisture content, meteorological conditions, and terrain characteristics. The Adriatic Sea coastal area in Croatia has a long record of devastating wildfires that have caused severe ecological and economic damages as well as the loss of human lives. Assessing the conditions favorable for wildfires and the possible damages are crucial in fire risk management. Adriatic settlements and ecosystems are highly vulnerable, especially during summer, when the pressure from tourist migration is the highest. However, available fire risk models designed to fit the macro-scale level of assessment cannot provide information detailed enough to meet the decision-making conditions at the local level. This paper describes a model designed to assess wildfire risks at the meso-scale, focusing on environmental and anthropogenic descriptors derived from moderate- to high-resolution remote sensing data (Sentinel-2), Copernicus Land Monitoring Service datasets, and other open sources. Risk indices were integrated using the multi-criteria decision analysis method, the analytic hierarchy process (AHP), in a GIS environment. The model was tested in three coastal catchments, each having recently experienced severe fire events. The approach successfully identified zones at risk and the level of risk, depending on the various environmental and anthropogenic conditions.

Variability of hydrographic and biogeochemical properties in the North-western Adriatic coastal waters in relation to river discharge and climate changes

The dynamics of hydrographic and biogeochemical properties in a Northwestern coastal area of the Adriatic Sea were investigated. The time series data from continuous observation (2007–2022) allowed the investigation of annual trends and seasonal cycles along a coastal transect influenced by local river discharge. Various statistical models were used to investigate water temperature, salinity, chlorophyll a, dissolved organic, inorganic and particulate nutrients, precipitation and river discharge. It was found that the local river discharge regime played an essential role in interannual, and seasonal biogeochemical dynamics associated with global climate change in the Mediterranean region. A significant trend towards oligotrophic conditions was detected, as evidenced by the downward trend in the river mouth and on the sea of chlorophyll a (−0.2 μg L−1 in the sea), dissolved organic and inorganic nitrogen and phosphorus (i.e., −0.43 μM yr−1 of DON in the sea and −6.67 of DIN μM yr−1 in the river mouth or −0.07 μM yr−1 of DOP and −0.02 μM yr−1 of DIP in the river mouth) and silicate (−2.47 μM yr−1 in the river mouth) concentrations. Salinity showed a long-term increase in the sea (0.08 yr−1), corresponding to a significant decrease in water discharge from the local river (−0.27 m3 s−1 yr−1) and precipitation (−0.06 mm yr−1). The dissolved organic and inorganic nutrients highlighted a different seasonal accumulation under the river runoff regime. The nutrient enrichment was predominantly driven by river contribution. Data analysis showed that the coastal biogeochemical properties dynamics were mostly influenced by river discharge and precipitation regimes, which in turn are driven by climate change variability in the North-western Adriatic Sea.

Paleoclimate changes and ecosystem responses of the Bulgarian Black Sea zone during the last 26000 years

Multi-proxy analysis (spore-pollen, dinoflagellate cysts, other non-pollen palynomorphs (NPPs), radiocarbon dating and lithology) was performed on marine sediments from three new cores retrieved during the two cruise expeditions on board the Research Vessel “Akademik” in 2009 and 2011. The Varna transect comprises three cores extending from the outer shelf, continental slope and deep-water zone. The record spans the last 26000 years (all ages obtained in this study are given in calendar years BP (cal. yrs BP)). The pollen record reveals the spreading of steppe vegetation dominated by Artemisia and Chenopodiaceae, suggesting cold and dry environments during the Late Pleniglacial – Oldest Dryas (25903–15612 cal. yrs BP). Stands of Pinus and Quercus reflect warming/humidity increase during the melting pulses (19.2–14.5 cal. ka BP) and the Late Glacial interstadials Bølling and Allerød. The Younger Dryas (13257–11788 cal. yrs BP) coldest and driest environments are clearly demonstrated by the maximum relative abundance of Artemisia and Chenopodiaceae. During the Early Holocene (Preboreal and Boreal chronozones, 11788–8004 cal. yrs BP), Quercus appeared as a pioneer species and, along with other temperate deciduous arboreal taxa, formed open deciduous forests as a response to the increased temperature. The rapid expansion of these taxa indicates that they survived in Glacial refugia in the coastal mountains. During the Atlantic chronozone (8004–5483 cal. yrs BP), optimal climate conditions (high humidity and increased mean annual temperatures) stimulated the establishment of species-rich mixed temperate deciduous forests. During the Subboreal chronozone (5483–2837 cal. yrs BP), Carpinus betulus and Fagus expanded simultaneously and became more important components of mixed oak forests and probably also formed separate communities. During the Subatlantic chronozone (2837 cal. yrs BP to pre-industrial time), climate-driven changes (an increase of humidity and a cooling of the climate) appear to be the main drivers of the specific vegetation succession expressed by increased abundance of Alnus, Fraxinus excelsior and Salix along with lianas, suggesting formation of flooded riparian forests (so called ‘Longoz’) lining the river valleys along the Black Sea coast. The first indicators of farming and other human activities have been recorded since 7074 cal. yrs BP. The dinoflagellate cyst (dinocyst) assemblages have been analysed to assess the changes in the Black Sea environment over the last 26000 years in terms of fluctuation in paleoproduction and surface water conditions related to changes in climate, freshwater input and Mediterranean water intrusion. Two major dinocyst assemblages were distinguished: one dominated by stenohaline freshwater/brackish-water species and a successive one dominated by euryhaline marine species. The changes in the composition of the assemblages occurred at 7668 cal. yrs BP. The abrupt decrease of stenohaline freshwater/brackish-water species Pyxidinopsis psilata and Spiniferites cruciformis was followed upwards by a gradual increase in euryhaline marine species, such as Lingulodinium machaerophorum, Spiniferites belerius, S. bentorii and acritarch Cymatiosphaera globulosa. The first occurrence of euryhaline marine species took place synchronously with the onset of sapropel deposition. Modern marine conditions were established after 6417 cal yrs BP when an abundance of Mediterranean-related species, such as Operculodinium centrocarpum and Spiniferites mirabilis, along with other heterotrophic species, occurred. After the stable cold and dry environment during the Last Glacial Maximum, the phytoplankton record of core AKAD 11-17 shows that Pediastrum boryanum var. boryanum has a cyclical abundance associated with the deposition of four red-brown clay layers between 19.2 and 14.5 cal. ka BP. This event is associated with the major melting phase of European Ice drained by the Danube and Dnieper Rivers in response to climate warming observed after the end of the Last Glacial Maximum. During the Early Holocene, P. psilata, characterised by a preference to warmer temperatures, demonstrates its ecological optimum for growth concerning SST reaching maximum relative abundance of 94% between 11072 and 8638 cal. yrs BP. This maximum was interrupted by an abrupt significant short-term decrease in the relative abundance of P. psilata centred between 8500 and 8300 cal. yrs BP reflecting cold conditions similar to those of Younger Dryas. This finding, also confirmed by the rapid significant decrease of arboreal pollen, particularly of Quercus in the same studied core, is considered a regional expression of the well-known ‘8.2 ka cold event’ which is commonly linked to a meltwater-related perturbation of the Atlantic Meridional Overturning Circulation (AMOC) and associated collapse of oceanic northward heat transport. Our fossil pollen and dinocyst data confirm that the high amplitude temperature anomaly associated with ‘the 8.2 ka cold event’ may have also occurred in south-eastern Europe, at lower latitudes of the western Black Sea coastal area, most probably due to atmospheric transition and/or river discharge.

Diabatic heating structures varying with convective and rainfall intensities in different areas of the pan-South China Sea region

This study investigates and compares diabatic heating structures related to vertical velocity, cloud types, and rainfall intensities in the northeast rainy sea subregion named Dongsha, the west rainless sea subregion named Xisha, and the north rainy land subregion named Coastland in the pan-SCS region. The diabatic heating rate of >2 K hr−1 over Dongsha and Coastland has a higher frequency and a deeper distribution than over Xisha where it requires stronger upward motion to achieve the same heating rate, indicating more frequent and deeper convection over the north coastal sea and land areas than the west sea area of the pan-SCS region. The deep convective Q1 profiles show a stronger peak at ∼500 hPa and a weaker peak at ∼700 hPa over two sea subregions while a single peak at ∼500 hPa over Coastland. The nimbostratus Q1 profile has a weakened heating peak at 350–550 hPa over Dongsha, 500–600 hPa over Xisha, and 425–575 hPa over Coastland. The shallow cumulus Q1 profile of Dongsha shows weak heating in the mid-to-lower troposphere while that of Xisha and Coastland has hardly heating. Latent heating and vertical turbulence significantly affect the diabatic heating structure related to deep convective clouds and nimbostratus but hardly affect that related to shallow cumulus. Despite cloud types, Dongsha has the strongest diabatic heating among the three subregions due to its geographical advantages. The no-rainfall Q1 profiles over three subregions have a similar shape with a weak cooling peak at ∼700 hPa due to boundary-layer evaporation and eddies. But the small-rainfall Q1 profiles present upper heating and lower cooling over sea subregions whereas the opposite over Coastland possibly due to stronger surface sensible heating on the land. From moderate to heavy rainfall, the Q1 profiles over three subregions are similar with a heating maximum at ∼500 hPa associated with deep convection, except for heating intensity which is much stronger over Xisha than the other two subregions. This suggests that Xisha presents stronger convection to achieve the same rainfall intensity as Dongsha and Coastland, which is closely due to a positive effect of coastal terrain blocking and uplifting on precipitation for Dongsha and Coastland whereas a negative effect of the Annam Mountains for Xisha.

Inventorization and ecological risk assessment of tetrabromobisphenol A and hexabromocyclododecane in sediments from Guangdong coastal area of South China Sea

Brominated flame retardants (BFRs) exhibit excellent flame retardant properties and are widely used in various industries. Among the common BFRs, tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDs) pose substantial ecological and human health risks due to their extensive application and long-range transport. This study established 131 sample collection sites along the coast of the South China Sea (SCS) in Guangdong Province to assess the concentration, distribution, inventory, and ecological risk of TBBPA and HBCDs in surface sediments. The concentrations of TBBPA in SCS sediments ranged from < limit of detection (LOD) to 80 μg/kg dry weight (dw), and those of HBCDs from < LOD to 18 μg/kg dw. The diastereoisomers of HBCDs (α-, β-, and γ-HBCD) in the sediment samples accounted for 36 %, 13 %, and 51 %, respectively. Human activities, particularly those associated with nearby electronic waste disassembly and textile and garment industries, considerably influenced the dispersion of TBBPA and HBCDs. The inventories of TBBPA and HBCDs in Guangdong Province's SCS were estimated to be 3.2 × 105 kg and 7.2 × 104 kg, respectively. The average risk quotient values ranged from <0.01 to 0.016, indicating a low to negligible environmental risk. This study provides deeper insights into the distribution and scientific significance of HBCDs and TBBPA in SCS sediment samples, elucidates the current state of BFR contamination, and offers recommendations for future research on environmental safety and human health in the region.

Обеспечение радиопокрытия прибрежной морской зоны с применением беспроводного широкополосного оптического канала для организации интенсивного судоходства

The model of a wireless broadband optical channel designed for communication between the coastal subsystem and an air repeater that provides coverage of the coastal sea area for the organization of intensive navigation, including the use of unmanned vessels is presented. It is shown that direct coast-to-ship data transmission using Wi-Fi and 4G/LTE technologies has a number of disadvantages for bays with complex coastal terrain. The use of a wireless optical channel in the "point-to-point" format between the coastal subsystem and the air transmitter makes it possible to provide high-quality radio coverage of the sea surface and provide information-intensive channels to ship systems. The results of modeling the wireless optical channel implemented using FSO (Free Space Optic) technology are presented. To increase the efficiency of using the spectrum of the transmitted data stream and the protection ratio of the wireless channel, 16QAM and OFDM are used.

Beta diversity and regionalization of the western Atlantic marine biota

AbstractAimUnderstanding the factors determining marine community variations is important for biogeography and conservation. Beta diversity is a metric for mapping species composition variations between communities and regionalizing biota. Ecoregions are commonly used for regionalization, but their empirical testing has been limited. Our aim is to map marine species composition variations in the Western Atlantic, identify variables related to these variations, and regionalize areas based on community distribution. Additionally, we test whether currently proposed ecoregions represent unique biota units and specific environmental conditions.LocationWestern Atlantic Ocean.TaxonVertebrates, invertebrates and algae.MethodsWe constructed a large marine biodiversity database, including vertebrates, invertebrates, and algae, totalling over 4 million records. We used the generalized dissimilarity model (GDM) to identify variables most related to species composition variations and map beta‐diversity variations. We employed an unsupervised classifier for community regionalization. To test if the ecoregion regionalization boundaries are corroborated by species distribution data, we used the Sørensen index. To assess if ecoregions correspond to environmental units, we checked if areas had distinct environmental conditions using a PCA of 134 marine environmental variables.ResultsThe GDM explained a high variation in species composition, 61% in the complete database. Analysing vertebrates, invertebrates and algae separately also yielded relatively high results: 46%, 54%, and 33%, respectively. Coastal areas differed from open sea areas in composition. Environmental variables combined better explained beta diversity than isolated variables. The regionalization based on GDM was not congruent with ecoregion boundaries. Moreover, ecoregions showed no distinction in species composition or environmental conditions.Main ConclusionsThis study's regionalization is crucial for marine biodiversity conservation, focusing on understanding species composition patterns between coastal and open sea areas to develop tailored conservation strategies. Despite sampling limitations, the study advances marine biogeography knowledge by analysing over 4 million species records and 134 environmental variables. This comprehensive approach enhances understanding marine species distribution and diversity and aiding the development of effective conservation measures.

Indices and methods for evaluating gross ecosystem product in sea areas: a case study in Changdao County, China

IntroductionCoastal nations heavily rely on their sea areas to achieve sustainable socioeconomic development. Sea areas offer abundant marine ecosystem products and services that are difficult to substitute with industrial goods. Although considerable research has been performed to evaluate the contribution offrom the marine ecosystems to human well-being, systematic and measurable indices are lacking.MethodsTo address this knowledge gap, ecosystem service theory was used to establish a framework for assessing the gross ecosystem product (GEP) of a sea area, which represents the total monetary value of final ecosystem products directly and indirectly used by people within a specific administrative jurisdiction in one year. To evaluate marine GEP, three primary indices, i.e., material products, regulating products, and cultural products, were employed, and they consist of eight secondary indices. Material products in the sea area include aquatic products and oxygen products; regulating products include carbon sequestration, climate regulation, waste treatment, and coastal protection; and cultural products include leisure and recreation, and seascape-added value. The marine GEP was calculated for the administrative sea areas of Changdao County, which is located in the Yellow Sea-Bohai Sea transitional zone.Results and discussionOur analysis indicated that from 2017 to 2019, the marine GEP in Changdao ranged between 32.59 and 33.35 billion Chinese yuan (CNY). Regulating products contributed two-thirds of this total value. However, over the three-year period, the marine GEP underwent a 5.64% decrease in Changdao. Specifically, the value of material products increased by 38.85% while that of regulating and cultural products decreased by 9.16% and 15.87%, respectively. Notably, the spatial distribution of ecosystem product values in Changdao displayed two prominent trends: (1) higher values along the coastal sea areas of islands and lower values in offshore sea areas; and (2) higher values in coastal areas of southern islands and lower values in coastal areas of northern islands. Marine GEP may serve as a comprehensive indicator for assessing the sustainability of marine ecosystem. Combining the assessment of both marine and terrestrial GEP facilitates an understanding of how marine and terrestrial ecosystems interact in coastal regions. Furthermore, the combined use of marine GEP and GDP helps better evaluate and sort the level of green development of coastal nations and regions.

Foreign Experience Review on Engineering Protection of Seashores and Hillslopes

Introduction. During design, construction and operation of buildings and structures in the coastal areas there arises a serious problem of engineering protection of coasts and hillslopes from the dangerous geological processes, which include the coastal erosion, underflooding of territories, hillslope erosion, gravitational (slope) processes, such as intensification of landslides, etc. These processes often result in significant economic damage usually related to the non-recoverable loss of valuable coastal territories, deformation of buildings and structures, damage and destruction of the objects of transport and engineering infrastructure. In this regard, the study of the advanced foreign experience in engineering protection of the coastal areas and the evaluation of the possibility of it to be implemented in Russia is a relevant scientific and engineering task.Materials and methods. To prepare the review, the following data was used: field observation data with photographic evidences of the objects of engineering protection of seashores and hillslopes obtained by the authors during a business trip to the People's Republic of China (PRC) in October–November 2023; study and analysis of literature sources in the subject area, including the methods and technologies implemented in the Netherlands, Japan, the USA, Great Britain, Italy; summary and systematisation of the coastal protection methods for further development of their classification and evaluation of the possibility of implementing thereof in the Russian Federation.Research results. The main principles of design, the advanced methods and technologies of coastal protection used in China have been defined. They include: construction of the multi-level protective structures, such as the multiple-row breakwaters of special shape in combination with the stepped retaining walls, the vertical walls consisting of the driven piles, anchoring and spray-concrete covering of the slopes in combination with the metal meshes; terracing in combination with the retaining reinforced concrete (horizontal and vertical) crossbeams; the sloping wave-absorbing reinforced concrete surfaces; the meshy structures and fences combating the Aeolian processes, etc.The main methods used in the Netherlands, Japan, the USA and Italy for comprehensive protection of the large territories have been defined. Such as: the network of dams, weirs, wave breakers, coast paving, regulation of the flows by water locks and barriers, creation of the artificial protective islands; artificial replenishment with sand; creation of the green spaces along the coast; forming the dunes — natural or artificial hills of sand or pebbles located along the coast; creation of the concrete structures, stone jetties, floating constructions and even artificial reefs.The importance of management was emphasised, including the early warning systems for storms and tsunamis, weather and marine condition monitoring systems, as well as dissemination of the warning messages and evacuation plans among the population in the areas of potential threat.Discussion and conclusion. Based on the results of the review, the main conclusions were formulated. The recommendations were given on the possible ways of improving the coastal protection of the Caucasian Black Sea Coast and other coastal areas of the Russian Federation based on the advanced foreign experience.

Epidamnus/Dyrrahchium (Durres) coins and hoard in the Mediterranean territories from 4th to 3rd centuries BC: A spatial distribution analysis

The study of the territorial distribution of Epidamnus/Dyrrahchium coins is a relevant topic in the context of the study of the history of Antiquity, because by studying the history of numismatics, a number of general historical conclusions can be made. The purpose of this article is to study and analyze the territorial distribution of Epidamnus/Dyrrahchium coins in the 4th-3rd centuries BC. In the course of conducting this research, a number of methods were used, in particular: analysis, synthesis, comparison, specification and generalization. As a result of the study, the history of the coinage of Epidamnus/Dyrrahchium was considered, and the characteristic features of the first coins were determined. All the finds of Epidamnus/Dyrrahchium coins were also framed and displayed on the map. It was determined that the coins of the 4th century BC were mostly spread on the coastal area of the Adriatic Sea, which is evidence of maritime trade, and also in Sicily, which is the result of military campaigns. In the 3rd century BC coins of Epidamnus/Dyrrahchium appear in the territory of modern Romania and Bulgaria, which indicates the development of overland trade routes. Many coins were also found in the territory of coastal cities, which indicates a stronger development of sea trade. This article is the first comprehensive study of the territorial distribution of Epidamnus/Dyrrahchium coins, and is useful for historians studying the economic and military aspects of Antiquity.

Choosing the profile of an inclined – directional well in the Caspian Sea area of Turkmenistan

This paper aims to design a profile for a directional and production-appraisal well, specifically Well No. 707 in the West Cheleken field, situated in the Caspian Sea coastal water area. In the context of rapid changes in the energy sector, this study holds significance, offering economic benefits and contributing significantly to the energy security of the region and the global energy market. The main objective of this study is to optimise directional drilling for exploration wells in the Caspian Sea area of Turkmenistan, specifically focusing on improving efficiency and reducing environmental impact. To achieve this research objective, the author proposes designing a profile for a directional and production-appraisal well, utilising materials from geophysical surveys of previously drilled wells. This approach aims to avoid accidents and complications during the drilling process. Both the Close Approach software and safety regulations in the oil and gas production industry are employed to prevent collisions of wellbores. In conclusion, this research contributes innovative solutions to optimise directional drilling processes for exploration wells. It addresses potential complications in open wells and, importantly, mitigates the risk of wellbore collisions. Keywords: wellbore collision; complication; stabilization; accident; Apsheron; Akchagil; curvature; displacement.

Spatial and temporal distribution of physicochemical parameters of water in Gorgan Bay (the southeast of the Caspian Sea - Iran): Fundamentals for the monitoring of the Caspian Sea coastal areas

Gorgan Bay as a main part of the Miankaleh (a natural biosphere reserve registered by UNESCO) is one of the richest ecological area in the West Asia and very important internationally recognized refuge for the wildlife. To date, multi physicochemical parameters have not been examined on a large scale. To fill this knowledge gap, the present study aimed to explore the seasonal and spatial variability of water quality parameters of the bay. The results showed that except for depth and transparency, there are significant variations in most parameters across the four seasons. The patterns of these changes in the bay vary, as evidenced by a comparison of the distribution maps of the various factors throughout the year. Notably, alkalinity declined from east to west, reaching its highest levels at important entry points such as the Qarasu River, Bandar-Gaz, and the pier. TDS, on the other hand, increased westward, reaching its highest concentration in the shallow western regions. Maximum depth (310 cm) and transparency (250 cm) were observed in the central bay. While the pH was higher in deeper areas, the distribution of PO4 was more uniform. With lower levels in the east (salinity = 0.40 ‰) and higher levels in the west (salinity = 28.9 ‰), the salinity showed a coherent gradient. Agricultural land use in the basin of the bay and fluxes of nutrients and sediments of the rivers entering the bay has significant contribution to the bay pollution situation. These results will serve as a guide for improving our understanding of the Gorgan Bay ecosystem. They also have implications for informed conservation and management plans adapted to the specifics of this special region within the Caspian Sea.

Simulating the impact of typhoons on air‐sea CO2 fluxes on the northern coastal area of the South China Sea

The South China Sea is a typhoon-prone region, and previous studies have shown that typhoons have significant impacts on air-sea CO2 fluxes. However, the effect of typhoons on the northern coastal area of the South China Sea is not well understood owing to limited observational data. In this study, we used a coupled model to simulate the impact of four typhoons (Hato, Mangkhut, Nida, and Merbok) on the partial pressure of CO2 in seawater (pCO2sea) and the CO2 fluxes in this area. Our results show that the coupled model effectively reproduces the spatial pattern of pCO2sea in this region. The response of pCO2sea to typhoons was determined by typhoon-induced vertical mixing and coastal upwelling, along with initial oceanic conditions. Typhoon Nida caused a decrease in pCO2sea with Total Alkalinity and Sea Surface Temperature being the primary factors. However, typhoons Hato, Mangkhut, and Merbok caused an increase in pCO2sea with Dissolved Inorganic Carbon playing a more prominent role. The average CO2 fluxes during the passage were approximately 6–14 times higher than those before typhoon passage. These results enhance our understanding of the effect of typhoons on air-sea CO2 fluxes over the northern coastal area of the South China Sea.