Depositional and stratigraphic evolution of a Permian megalake system: Implications for seiche‐influenced models

The mid-to late Miocene Lake was a primarily closed, saline lake which during its lifetime underwent a series of rapid salinity changes associated with faunal extinctions/radiations. The first two of these, at the Badenian/Sarmatian and Sarmatian/Pannonian boundaries signify the transition from a marine basin to a brackish lake and are marked by major faunal changes. The isotopic composition of molluscs from the lake, however, does not undergo major changes. The third transition, at the end of the Pannonian and into the Pontian, is also marked by major faunal changes, thought initially to reflect further freshening of the lake. Both carbon and oxygen isotope ratios of lake molluscs decrease by 4 to 6%oo at this transition. A consideration of salinity and oxygen isotope mass balances for a closed or nearly-closed lake shows that major changes in salinity accompany relatively minor changes in water balance and isotopic composition. This result explains why the oxygen isotope ratio of lake waters did not change during the initial freshening of the lake and suggests that the major isotopic changes observed later are not directly related to changes in the lake water balance which caused the salinity changes. The isotopic variations were driven mainly by other climatic factors, most likely changes in humidity and isotopic composition of inflow.

With 20 years of operations, multiphase flowmeters (MPFMs) using a combination of venturi and multi-energy gamma-ray absorption have gained acceptance in the oil and gas industry by demonstrating reliable measurement and operational robustness. Nonetheless, some challenging operating scenarios are encountered such as significant water salinity changes in multiphase and wet-gas flows and rapid detection of small water quantities during production. Although MPFMs are not affected by small water salinity changes, inaccurate flow rates can be calculated when water salinity significantly departs from the initial properties. To maintain measurement metrology as per specifications, the water-point should be manually modified to track variations; however, this operation is time consuming and may incur nonproductive time. Interpreting the multiphase mixture's dielectric constant and electrical conductivity simultaneously measured by a new microwave water salinity sensor at a high data acquisition rate shows that water salinity can be tracked online in the presence of oil, gas, and sand, and small water quantities can be detected rapidly in multiphase and wet-gas flows. The detection of the first produced water is of paramount importance in many applications, such as for fields with high H2S production, where existing processing plants usually have limitations in treating produced water with dissolved H2S. Early detection of produced water in oil is required, enabling operators to take informed decisions about the oil production strategy as well as water treatment and corrosion protection plans. Extensive analyses in flow loops and field operations with the new microwave water salinity sensor demonstrate that the water detection limit is lowered from the typical ∼1000-ppm water volume fraction (WVF) for the MPFM to a remarkably low 50 ppm. This paper describes the working principles of a new sensor and method, that enable additional capabilities to maintain accurate water-liquid ratio (WLR) measurement in situations where significant water salinity changes occur and to provide a rapid, much lower WVF detection level. Successful cases demonstrating first-water detection in flow loop tests and in field operations are also presented.

With 20 years of operations, multiphase flowmeters (MPFMs) using a combination of venturi and multi-energy gamma-ray absorption have gained acceptance in the oil and gas industry by demonstrating reliable measurement and operational robustness. Nonetheless, some challenging operating scenarios are encountered such as significant water salinity changes in multiphase and wet-gas flows and rapid detection of small water quantities during production. Although MPFMs are not affected by small water salinity changes, inaccurate flow rates can be calculated when water salinity significantly departs from the initial properties. To maintain measurement metrology as per specifications, the water-point should be manually modified to track variations; however, this operation is time consuming and may incur nonproductive time. The salinity change measured by a newly developed sensor can be provided seamlessly to MPFMs to automatically update the water point calibration, thus ensuring good flow rate measurement performance over a wider water salinity range. Extensive validations at several flow loop facilities and field tests, including frac flowback operations, demonstrate the robustness of the method in terms of hardware reliability and the delivery of high-quality data when used with MPFMs with digital connectivity, which opens the way to unmanned production monitoring operations. Interpreting multiphase mixture's dielectric constant and electrical conductivity simultaneously measured by the new microwave water salinity sensor at a high data acquisition rate shows that water salinity can be tracked online in the presence of oil, gas, and sand, and small water quantities down to 50 ppm (part-per-million) water volume fraction (WVF), from the typical ~1000-ppm WVF for the MPFM, can be detected rapidly in multiphase and wet-gas flows. This paper describes the working principles of the new sensor that enable additional capabilities to maintain accurate water-liquid ratio (WLR) measurement in situations where significant water salinity changes occur and to provide a rapid, much lower WVF detection level. Successful cases demonstrating an accurate real-time salinity monitoring in flow loop tests and in field operations are also presented.

Salinity and flow regime independent multiphase flow measurements

Effect of changes in water salinity on ammonium, calcium, dissolved inorganic carbon and influence on water/sediment dynamics

Gill transcriptomes analysis of Takifugu obscurus, Takifugu rubripes and their hybrid offspring in freshwater and seawater

A significant number of rivers heavily influenced by anthropogenic pressures are not monitored (or monitored infrequently). For this reason, there is a need to develop modern methods allowing for the ongoing observation of water quality parameters, of which salinity is a key one. As a result of patrol monitoring information on changes in conductivity in the longitudinal profile of the Oder were obtained. The aim of this study is to correlate these results with Sentinel – 2 satellite imagery (VIS + NIR bands) to verify the hypothesis that remote sensing methods can be used to detect salinity changes in inland flowing waters. For this purpose data acquired with the multi-parameter probe during field expeditions, remote sensing methods and Geographical Information Systems tools (such as inter-bands algebra, pixel value extraction) and statistical methods were used. We concluded that the best spectra for salinity detection is Green as well as Salinity Index (SI) mostly showed statistically significant correlations. Remote sensing can be successfully used to detect changes in the salinity of flowing waters.

The European seabass is an active euryhaline teleost that migrates and forages in waters of widely differing salinities. Oxygen uptake (MO2) was measured in seabass (average mass and forklength 510 g and 34 cm, respectively) during exercise at incremental swimming speeds in a tunnel respirometer in seawater (SW) at a salinity of 30‰ and temperature of 14°C, and their maximal sustainable (critical) swimming speed (Ucrit) determined. Cardiac output (Q) was measured via an ultrasound flow probe on their ventral aorta. The fish were then exposed to acute reductions in water salinity, to either SW (control), 10‰, 5‰, or freshwater (FW, 0‰), and their exercise and cardiac performance measured again, 18 h later. Seabass were also acclimated to FW for 3 weeks, and then their exercise performance measured before and at 18 h after acute exposure to SW at 30‰. In SW, seabass exhibited an exponential increase in MO2 and Q with increasing swimming speed, to a maximum MO2 of 339±17 mg kg−1 h−1 and maximum Q of 52.0±1.9 ml min−1 kg−1 (mean±1 SEM; n=19). Both MO2 and Q exhibited signs of a plateau as the fish approached a Ucrit of 2.25±0.08 bodylengths s−1. Increases in Q during exercise were almost exclusively due to increased heart rate rather than ventricular stroke volume. There were no significant effects of the changes in salinity upon MO2 during exercise, Ucrit or cardiac performance. This was linked to an exceptional capacity to maintain plasma osmolality and tissue water content unchanged following all salinity challenges. This extraordinary adaptation would allow the seabass to maintain skeletal and cardiac muscle function while migrating through waters of widely differing salinities.

The paper analyzes the variability of hydrological characteristics of the North-Western part of the Black for different temporal scales: long-term, seasonal and synoptic. The traditional methods of geographic investigations, such as comparative-geographic, retrospective and cartographic methods, were used. When analyzing sea level data packages and thermohaline characteristics mathematical methods, including statistical, correlation and regression analysis, were used. As a result of the conducted research quantitative estimates of tendencies of long-term changes of the thermohaline characteristics and level in the North-Western part of the Black Sea were received. Over the period of 1982-2005 an increase of water temperature in the North-Western part of the Black Sea was observed: in winter water temperature in the surface layer increased by 2оC, in the bottom layer – by more than 2оC. Over the period of 1990-2005 an increase of an average annual water temperature in Odesa area constituted 1,2°C. The most considerable and statistically significant temperature increase took place during the summer hydrological season: an average summer temperature increased during this period by 2,7оC. During transitional seasons (autumn and spring) there was also a tendency of temperature increase, however, statistically significant trend was observed only during the autumn period. There is a statistically significant negative trend observed for long-term changes of salinity. For the period of 1990-2005 an average annual salinity decreased by 1.36 ‰. A tendency of salinity decrease was observed for all seasons of the year, however, statistically significant trends are observed only in winter and summer. A close relationship between long-term changes in water salinity and runoff of the Dnieper River was also established. A sea level rise is observed at all stations of the North-Western part of the Black Sea. Over the period of 1947-2012 an average annual sea level in Odesa increased by 14 cm. An analysis of climatic changes of wind-induced sea level fluctuations showed that the frequency of surges of varying intensity remained almost unchanged, however, the frequency of sweeps changed significantly. Over the period of 1980-2012, as opposed to the period of 1947-1979, the frequency of minor sweeps (no more than 30 cm) increased, and the frequency of significant (more than 30 cm) and very significant (more than 50 cm) sweeps, on the contrary, decreased by about 5%-6%. Changes of wind-induced sea level fluctuations' character harmonize with wind direction and wind speed over the North-Western part of the Black Sea.

We studied the sedimentology, benthic foraminifera, molluscs, and δ18O and δ13C of Ammonia tepida tests in two late Holocene sediment cores from Lake Qarun (Egypt). The cores, QARU2 (upper section, 8.2 m) and QARU4 (1.4 m), span approximately the past 500 years of sedimentation. Benthic foraminifera first appeared in the upper part of QARU2 at 314 cm depth, ca. AD 1550. This depth marks the beginning of colonization of the lake by foraminifera and indicates a change in lake water salinity, as foraminifera cannot tolerate fresh water. Initially, three species of benthic foraminifera colonized the lake, Ammonia tepida, Cribroelphidium excavatum and Cribrononion incertum. Relative abundance of these species fluctuated throughout cores QARU2 and QARU4 and highest overall faunal diversity occurred at the beginning of the twentieth century. High relative abundances of C. incertum and deformed tests are attributed to periods of greater lakewater salinity. Peaks in both δ18O and δ13C indicate times of higher evaporation and reduced fresh water inflow. Inferred salinity was high around AD 1700 and after AD 1990. Rapid response of climate proxy variables indicates the high sensitivity of Lake Qarun to environmental changes over the past several 100 years. Increases in lakewater Mg concentration during past evaporative events, associated with less fresh water inflow, probably provided conditions suitable for C. incertum to build its white or transparent tests. Gradual decrease of C. incertum, until its disappearance at 100 cm depth ca. AD 1890, indicates a more persistent trend in lake water chemistry. Higher concentrations of dissolved sulphates were the likely cause of this species disappearance. Recent, twentieth-century sediments were deposited under optimal salinity (37‰) for benthic fauna, but further environmental changes are indicated by the decrease or disappearance of several benthic foraminifera and mollusc species. Intermittent hypoxia in the lake’s bottom waters, caused by cultural eutrophication, may account for these most recent changes.

Palaeolimnological approaches to climate change, with special regard to the biological record

Salt marshes are in danger of degradation due to human impact and climate change. A thorough understanding of mechanisms controlling sedimentation and erosion in salt marshes is essential for their conservation and restoration. To understand short‐term dynamics of sediment availability and deposition around marsh edges, two contrasting marshes, Rattekaai and Sint Annaland, were studied in the Oosterschelde (southwest Netherlands). Suspended sediment concentration (SSC) was measured by siphon samplers along four transects perpendicular to the marsh edge in each marsh, during nine flood tides between March and December 2013. Each transect was comprised of four sampling sites (−10 m and −1 m on the mudflat and +1 m and +10 m on the marsh plateau, relative to the marsh edge). Sediment deposition was measured along the transects on the marsh, at +1 m and +10 m from the marsh edge, over seven c. 14‐day intervals during the same 10‐month period. Two types of sediment traps were used, one measuring gross sediment deposition (TTD – tube trap deposition) and one measuring net sediment deposition (FTD – filter trap deposition). Wave loggers were deployed 10 m away from the marsh edge on the mudflat at each marsh. The results showed that both SSC and sediment deposition varied greatly through space, both between the two marshes and within each marsh along the marsh edge. The SSC and gross sediment deposition were much higher at Rattekaai than at Sint Annaland. SSC was significantly correlated with wind speed during sampling. Sediment deposition rates (TTD and FTD) and retention ratio (FTD/TTD) were significantly correlated with cumulative wave energy during the measurement period. A conceptual model of local sediment dynamics is proposed to explain the sediment dynamics around the marsh edge. This study highlights the importance of incorporating local sediment dynamics when evaluating marsh vulnerability and stability. Copyright © 2018 John Wiley & Sons, Ltd.

A high‐resolution, accelerator mass spectroscopy 14C dated sediment record from the Sulu Sea clearly indicates that the Younger Dryas event affected the western equatorial Pacific. Planktonic foraminiferal δ18O and abundance data both record significant changes during Younger Dryas time. In particular, a 0.4‰ increase in the δ18O value of Globigerinoides ruber and the reappearance of the cool water planktonic foraminifera, Neogloboquadrina pachyderma, occur during the Younger Dryas at this location. These isotopic and faunal changes are a response to either surface water temperature or salinity changes, or some combination of the two. Changes in surface salinities could have been accomplished through either local or global processes. Intensification of the monsoon climate system and increased precipitation at approximately 11 ka is one mechanism that may have resulted in local changes in salinity. A meltwater pulse derived from the Tibetan Plateau is another mechanism which may have caused local changes in salinity. The presence of the Younger Dryas in the tropical western Pacific clearly indicates that this climatic event is not restricted to the North Atlantic or high latitudes, but rather is global in extent.

Activity of antioxidant enzymes and physiological responses in ark shell, Scapharca broughtonii, exposed to thermal and osmotic stress: Effects on hemolymph and biochemical parameters

Changes in the fish community of the St Lucia estuarine system (South Africa) following Cyclone Gamede, an episodic cyclonic event