Suspended sediment budget and stability of the River Don Delta in the period from 1944 to 2020

The Tracking Atmospheric Rivers Globally as Elongated Targets (tARget) algorithm is further developed to Version 3, adding the capability to track atmospheric river (AR) life cycles along with other refinement. The results indicate AR genesis is more frequent toward the western boundaries of midlatitude ocean basins and nearby upstream land areas (~1 month−1) compared to the eastern boundaries (~0.5 month−1) and least frequent in tropical and polar areas (reaching toward 0). AR termination is more frequent toward the northeastern sectors of North Pacific/Atlantic and adjacent downstream land areas and in the Southern Ocean near Antarctica (~1 month−1) compared to the adjacent ocean sectors (~0.5 month−1) and least frequent in tropical areas and interior Antarctica where AR genesis is similarly infrequent. ARs tend to be longer‐lived when the genesis (termination) occurs toward the western (eastern) boundaries of midlatitude ocean basins and adjacent land areas (maximum lifetime >72 hr) compared to the opposite side of the ocean basins (24–72 hr) and when terminated at high latitudes. AR travel speed is higher in the midlatitude ocean basins and strongly steered by the zonal wind around 650 hPa. AR tracks are nearly linear in most cases, with the overall travel direction closely correlated with the direction of integrated water vapor transport (r = 0.69) although being more zonal than the latter. Temporally, ARs tend to be longer/stronger around the middle of the life cycle. Seasonal variations in AR life cycle characteristics are also examined. The handling of AR separations/mergers contributes the largest sensitivity in tracking result compared to selection/resolution of input data.

This paper examines soil temperature (Ts) in two different plantation forests relative to an adjacent open land area in a tropical highland environment. To achieve the objectives, Ts in a Juniperus procera (JP) plantation, a Grevillea robusta (GR) plantation, and in the adjacent open land (OL) area were measured. One-way ANOVA and Pearson’s correlation were used for the data analysis. The result indicated that the mean daily Ts in the OL area at 10-cm depth of the soil was greater than the mean daily Ts recorded in the JP and GR plantations by 5 °C and 6 °C, respectively. The OL area Ts recorded at different soil depths (10 cm and 20 cm) was significantly different (p < 0.05). Rainfall (RF) and air temperature (Ta) of the study area have a direct relationship with the Ts in the plantation forests. The RF and Ta do not have a significant relationship with the Ts in the OL area at 10-cm soil depth. Overall, the study indicated that the Ts in the open land area was highly fluctuating monotonically, while it is relatively constant in the plantation forests.

Analysis of new geophysical data on the Black Sea – Caspian Region acquired since late 90-ties, partial reprocessing and reinterpretation of archival geophysical and geological results of oil and gas prospecting both offshore and on adjacent land areas, systematization and generalization of the entire dataset enabled the represented corrections of traditional views upon tectonics and hydrocarbon potential of the Caspian Sea, the Black Sea, the Sea of Azov, and adjacent terrain.

Detecting environmental change in estuaries: Nutrient and heavy metal distributions in sediment cores in estuaries from the Gulf of Finland, Baltic Sea

A Bouguer gravity anomaly map is presented of the North Sea and adjacent land areas in Norway and Denmark, covering an area situated between 56° and 62°N, 1°W and 10°E. The gravity data from the UK sector of the North Sea, the land and offshore areas of Denmark, and the land areas of Norway have been published before. However, the gravity data from the Norwegian sector of the North Sea are new. A large number (about 60) of individual gravity features can be defined in the mapped area. Most of those situated in the UK sector of the North Sea and on land in Norway have been discussed earlier; however, most of the anomalies found elsewhere which are qualitatively interpreted here have not been discussed before. An interpreted Bouguer anomaly map is presented which identifies all these features.The majority of the gravity anomalies encountered in the mapped area can be shown to be associated with one of the following geological features: (i) basement highs, (ii) large bodies of heavy basic or ultrabasic rock in the crystalline basement, (iii) large igneous intrusions within the sedimentary column and thick accumulations of volcanic rocks or their associated eruption centers, (iv) major basement faults.Large‐scale geological structures such as the Central, Viking and Sogn Grabens and the East Shetland, Stord, Forth Approaches and Norwegian‐Danish Basins are essentially in isostatic equilibrium and are only locally marked by relatively weak gravity minima.A residual gravity anomaly map has been produced by subtracting from the observed Bouguer anomalies the estimated gravity effect of an assumed thinned crust. This residual gravity anomaly map shows a number of features of the Bouguer anomaly field with greater clarity.

Sediment cores, representing a range of watershed characteristics and anthropogenic impacts, were collected in 11 subalpine marshes in the Lake Tahoe basin, USA and vicinity in order to trace the effect of anthropogenic impacts on sedimentation and sediment accumulation rates. Cores were 210Pb-dated using a CRS model, and these data were used to calculate sedimentation rates and sediment accumulation rates, which were compared with environmental variables. Age-depth profiles indicated that sedimentation rates changed at different times in different marshes, and we separated sediment cores into two parts to show sediment characteristic and sediment-accumulation-rate changes. Ranges of dry mass accumulation rates and sedimentation rates were 0.081–1.356 kg m−2 yr−1 and 0.94–4.64 mm yr−1 in the upper core and 0.094–0.563 kg m−2 yr−1 and 0.57–1.75 mm yr−1 in the lower core. In general, the cores showed recent increases in sediment accumulation rates. Species composition was related to water quality, ...

Abstract. The MagellanPlus workshop “BlackGate” addressed fundamental questions concerning the dynamic evolution of the Mediterranean–Black Sea (MBS) gateway and its palaeoenvironmental consequences. This gateway drives the Miocene–Quaternary circulation patterns in the Black Sea and governs its present status as the world's largest example of marine anoxia. The exchange history of the MBS gateway is poorly constrained because continuous Pliocene–Quaternary deposits are not exposed on land adjacent to the Black Sea or northern Aegean. Gateway exchange is controlled by climatic (glacio-eustatic-driven sea-level fluctuations) and tectonic processes in the catchment as well as tectonic propagation of the North Anatolian Fault Zone (NAFZ) in the gateway area itself. Changes in connectivity trigger dramatic palaeoenvironmental and biotic turnovers in both the Black Sea and Mediterranean domains. Drilling a Messinian to Holocene transect across the MBS gateway will recover high-amplitude records of continent-scale hydrological changes during glacial–interglacial cycles and allow us to reconstruct marine and freshwater fluxes, biological turnover events, deep biospheric processes, subsurface gradients in primary sedimentary properties, patterns and processes controlling anoxia, chemical perturbations and carbon cycling, growth and propagation of the NAFZ, the timing of land bridges for Africa and/or Asia–Europe mammal migration, and the presence or absence of water exchange during the Messinian salinity crisis. During thorough discussions at the workshop, three key sites were selected for potential drilling using a mission-specific platform (MSP): one on the Turkish margin of the Black Sea (Arkhangelsky Ridge, 400 m b.s.f., metres below the seafloor), one on the southern margin of the Sea of Marmara (North İmrali Basin, 750 m b.s.f.), and one in the Aegean (North Aegean Trough, 650 m b.s.f.). All sites target Quaternary oxic–anoxic marl–sapropel cycles. Plans include recovery of Pliocene lacustrine sediments and mixed marine–brackish Miocene sediments from the Black Sea and the Aegean. MSP drilling is required because the JOIDES Resolution cannot pass under the Bosporus bridges. The wider goals are in line with the aims and scope of the International Ocean Discovery Program (IODP) “2050 Science Framework: Exploring Earth by Scientific Ocean Drilling” and relate specifically to the strategic objectives “Earth's climate system”, “Tipping points in Earth's history”, and “Natural hazards impacting society”.

Lacustrine sedimentation and trace metal accumulation are naturally occurring processes that can be altered by anthropogenic activities. Indices of sediment or metal dynamics are important for the management and operational use of man-made reservoirs and their drainage basins. In this study, we compared two reservoirs in Virginia, USA, to quantify the effect of varying watershed characteristics on sediment and metal fluxes. Lake Pelham is a human-impacted reservoir surrounded by agricultural fields and anthropogenic developments, whereas Lake Moomaw is an undeveloped reservoir surrounded by moderate to extremely sloping forested landscapes. Three sediment cores were taken from each reservoir to estimate 210Pb-based sediment accumulation rates, organic matter content, and indices of trace metal enrichment and accumulation. The average 210Pb-based sediment accumulation rates were 0.348 ± 0.053 and 0.246 ± 0.043 g cm−2 year−1 for Lake Pelham and Lake Moomaw, respectively. The sediment trace metal results showed strong correlation with sediment organic content, and both reservoirs had moderate to high enrichment of Cu and little enrichment of Zn and Pb. Overall, Lake Moomaw had relatively low sediment accumulation and metal enrichment. Comparatively, Lake Pelham had significantly greater metal concentrations, which were highest in the upper reaches of the reservoir. Lake Pelham also had higher sediment accumulation rates and higher metal enrichment, reflecting the impact of human development within the greater watershed. Results from this study suggest that urbanization can increase reservoir sediment and metal fluxes, but atmospheric deposition is also important in forested watersheds that have not undergone anthropogenic land-use change.

Recent sediment accumulation in the Skagerrak, Northeastern North Sea

Anthropogenic activities, particularly land reclamation and industrialization, have severely damaged South Korea’s intertidal zones, resulting in a decline in biodiversity. In our study, we assessed the macrobenthic community in the intertidal zone of Anmyeon Island, South Korea, and used remote sensing to evaluate the impact of anthropogenic activities on the adjacent land areas. Spearman and Principal Coordinate Analysis (PCoA) indicated that the remote-sensing ecological index (RSEI) is a viable indicator for assessing the dissimilarity of macrobenthic communities in these zones. Moreover, biota–environment matching (BIO–ENV) and distance-based redundancy analysis (dbRDA) demonstrated that land cover types significantly influence the macrobenthic communities in nearby intertidal zones. Our study suggested that urbanization and agricultural activities have affected the terrestrial ecological environment and the adjacent intertidal communities. Consequently, the protection of these zones should extend beyond their borders to include the management of anthropogenic activities on adjacent lands. Our research contributes valuable insights to help inform conservation strategies and the policy-making necessary to safeguard South Korea’s intertidal zones.

This paper presents a high‐resolution dual‐Doppler analysis of lake breeze mesoscale circulation induced by an elongated reservoir with a mean width of ∼2 km and an area of 125 km2. Compared to previous meso‐γ‐scale lake breeze studies based on point measurements or aircraft observations, the present study provides both a unique quantification and a high‐resolution spatial and temporal 3‐D visualization (several hundred meters and 5 min, respectively) of the kinematic structure of the lake breeze initiation and evolution. Visible satellite images show a cloud‐free zone over the lake and adjacent land areas that was promoted by subsidence associated with the lake breeze circulation. The background synoptic‐scale wind flow was almost parallel to the major axis of the lake, and distinct lake breeze frontal zones formed along both shorelines spanning the length of the lake. Dual‐Doppler analyses showed updrafts in the frontal zones, perturbation horizontal velocities of 1.5 m s−1 on both sides of the lake, and maximum downdrafts of 2 m s−1 centered over the lake. Vertical vorticity in the boundary layer was produced by differential friction between the smooth lake and adjacent land. The circulations are robust and are maintained during the day against a minor change in background wind direction. The study shows that the circulations produced by a small lake can generate significant mesoscale circulations that influence local climatology and identifies the importance of including such small mesoscale processes in global forecast models.

This paper presents the results of geomorphological studies carried out using the singular spectral analysis (SSA) complemented with geological and geophysical data. The SSA method was used to study the topography of the shelf and adjacent land areas in two scales. The large scale study covered the whole territory of the Southern Primorye and the Peter the Great Bay, the small scale — a major part of the Peter the Great Bay and the adjacent land in the northwest-ern direction. This technique of the relief analysis gives an opportunity to select different groups of elevations (modes in the relief), isolating them among the others, and to carry out geomorpho-logical studies based on discrete changes in the relief levels. Based on the geological and geo-physical data, it was determined that the area is located on a massive granite block. By analyzing the first (“older”) modes of the decomposition of the relief of the studied area, contouring of the massive block was carried out, and the choice of the location of the experimental hydrophysical ground was explained.

Accumulation of recent muds associated with coastal circulations, southeastern Korea Sea (Korea Strait)

The Caspian and Black Seas are adjacent inland bodies of water, each with its unique palaeogeographic history. The Black Sea has been connected to the World Ocean throughout its Quaternary history. In contrast, the Caspian Sea has been completely isolated since the beginning of the Middle Pleistocene. Since then, the Caspian Sea has occasionally discharged its excess waters through the Manych Depression into the Azov-Black Sea Basin. As a result of this isolation, unique species have developed in the Caspian Sea. The transgressive-regressive cycles of the Caspian Sea are associated with global and regional climate fluctuations since its sea level depends on its water balance. Due to the penetration of Caspian species into the Manych Depression and further into the Azov-Black Sea Basin, it is possible to determine episodes of its transgressive water discharge, assess the characteristics of the existing basins, and correlate these episodes not only with events within the Mediterranean—Black Sea—Caspian corridor but also with global events. The study of the connection between the Black and Caspian Sea basins dates back to the 18th century. Thereafter, numerous publications have addressed various aspects of the palaeogeography of the region. However, the events within these two basins during Marine Isotope Stage 5 (MIS 5) and their scales and characteristics remain debated. This research focused on studying the MIS 5 Epoch, which includes the Holocene-analogous Eemian interglacial period and the transition to the Early Weichselian glacial Epoch. To reconstruct the events in the Black Sea—Manych Depression—Caspian Sea during MIS 5, we conducted lithological, malacofaunistic, and geochronological analysis on six borehole sections in the Northern Caspian, four in the Manych Depression, and three in the northeastern sector of the Black Sea to identify events that occurred in basins, assess their environmental characteristics, conditions of sedimentation and time frames. We have discovered that the Karangatian transgression (analogous to the Eemian transgression in the Mediterranean Sea) ingressed into the Manych Depression 125–110 ka BP (MIS 5e–d) during its maximum phase and formed a gulf there with a water salinity of up to 18‰, featuring Mediterranean mollusc fauna. Later, the waters of the Hyrcanian transgression of the Caspian Sea exceeded the water divide of the Azov-Black Sea and Caspian Sea basins and began to spill over into the Manych Depression. This influx of water resulted in the desalination of the sea gulf that was present there, reducing its salinity to values of less than 14‰. This event occurred around 110–105 ka BP (MIS 5c). The Karangatian waters eventually left the Manych Depression, but Hyrcanian waters continued to flow into the Black Sea until ~ 100 ka BP. This is evidenced by characteristic Hyrcanian species, such as Didacna cristata and D. subcatillus, found in the upper part of Karangatian sediments in the Manych Depression and on the northeastern shelf of the Black Sea. The Hyrcanian water discharge marked the initial flow of Caspian water into the Black Sea during the late Pleistocene, occurring unilaterally without any exchange between these two basins. Reconstructing the transition from the interglacial to the glacial period during MIS 5 can provide valuable insights into the expected changes in the Black Sea—Manych Depression—Caspian Sea system as we move from the current Holocene interglacial into a new glacial period.

The recent development of a diving bell, designed to carry a gravimeter and observer, enables the geophysicist to make correct gravity observations on a river, lake or ocean floor. The bell, for which patents have been applied, is designed to operate in depths of water as great as 250 feet. It has been used with good results at depths ranging from 8 to 70 feet.Data taken from adjacent land and sea areas have been contoured and the smoothness of the resulting contours indicates that the underwater gravity readings are entirely reliable.Structural features of the diving bell and related equipment are described and plates showing exterior and interior views of the bell are given.