Salinity Variations Research Articles

Precision agriculture predictive modeling and sensor analysis for enhanced crop monitoring

This research investigated the application of the Internet of Things (IoT) in precision agriculture and crop monitoring through a two-fold research methodology. A simulated dataset was generated, mirroring real-world IoT sensor readings of soil temperature, salinity level, soil moisture, and conductivity. Employing the Pandas and Matplotlib libraries in Python facilitated exploratory data analysis, including time series analysis through line plots to illustrate temporal variations in these critical parameters. The study then explored the evaluation of predictive models for soil moisture levels, extending the dataset to include simulated predicted values. Performance metrics such as Mean Squared Error (MSE) and R-squared (R2) were computed using the sci-kit-learn library, providing a comprehensive evaluative framework. Visual representations of actual versus predicted soil moisture levels, accompanied by the analysis of residuals, offered nuanced insights into the model’s efficacy. The results highlight dynamic variations in soil temperature, salinity, soil moisture, and conductivity, emphasizing the importance of continuous monitoring in precision agriculture. Fluctuations observed in these parameters are attributed to climatic conditions, agricultural practices, and soil properties. The study contributes valuable insights for stakeholders, emphasizing the significance of IoT technologies in providing actionable data for sustainable and adaptive farming practices. The visual representations offer practical tools for decision-making, while the performance evaluation of predictive models enhances the reliability of data-driven approaches in agriculture. The findings presented herein contribute to the ongoing discourse on precision agriculture, emphasizing the role of accurate predictions for efficient resource utilization and improved crop yield.

Flocculation under combined effects of hydrodynamic and subaqueous biomass in the bottom boundary layer (BBL) of a microtidal estuary

The flocculation dynamics within the bottom boundary layer (BBL) of tidal estuaries constitute a pivotal and intricate aspect entwined with hydrodynamics and morphodynamics. In microtidal estuaries, where saltwater intrusion occurs, the ensuing impacts on ecosystems, biological habitats, and human activities underscore necessity for comprehensive understanding. In pursuit of elucidating flocculation dynamics within estuarine BBLs, an extensive 25-hour survey was conducted throughout a complete tidal-cycle in the Huangmaohai estuary, China. This investigation encompassed the collection of data pertaining hydrodynamics, biochemical characteristics of suspended flocs within the BBL. The observed irregular semidiurnal tide was delineated into six distinct stages: I) Weak flood, II) Flood slack, III) Strong ebb, IV) Ebb slack, V) Strong flood and VI) Flood slack. The amalgamation of empirical findings and theoretical analyses has facilitated the development of conceptual model delineating the intricate processes and interactions of multiple factors within each stage (I-VI) in the BBL of a prototypical micro-tidal estuary. Notably, it reveals biological factors exhibit a significantly higher efficacy in estuarine flocculation dynamics within the BBL compared to the chemical ion attractions, attributable to variations in salinity. Further nuances emerged, indicating that semi-liquid extracellular polymeric substance (EPS) plays a substantial role in the formation of high-density flocs, particularly during periods of heightened turbulent shear conditions in flood and ebb times (I, III, V). Conversely, particulate biological debris predominantly contributes to low-density flocs characterized by a low settling velocity, particularly for large flocs >200 μm during tidal slacks (I, IV), and smaller median-sized flocs (70–200 μm) during flood or ebb times (III, V) due to turbulent induced breakage of bio-particles. This study underscores the significance of quantitative investigations into the biological components within individual flocs under estuarine hydrodynamics as a pivotal step towards comprehending flocculation mechanisms and predicting cohesive sediment transport within the BBLs of estuaries.

Assessment of pollutants in coastal waters, sediments, and biota of marine ecosystems in Algeria, North Africa

This study aims to assess the chemical and ecological quality of the marine ecosystem in Algerian central coastal zone (Bay of Algiers (AB) and Bou-Ismail Bay (BIB)) by examining several quality indicators of the marine ecosystem: water, sediment, and biota. Except for stations near the mouths of wadis and industrial and urban discharges released without prior treatment, the study of the physicochemical water quality in the different sampling stations revealed a more or less normal variation in temperature and salinity. According to nutrient salt analysis, all studied stations (in AB and BIB) have high nitrogen levels, such as ammonium and nitrate. However, low levels of phosphate were detected, indicating that this element is scarce in the Algerian coastal marine waters. Three trace metals were also analyzed in the sediments of both bays. Pb ranged from 21.15 to 52.69 μg g–1 dry weight (dw), Zn from 19.32 to 175.1 μg g–1 dw and Cd between 0.87 and 2.031 μg g–1 dw. Contamination factors ranged from 0.62 to 1.55 for Pb, 0.2 to 1.85 for Zn and 1.74 to 4.04 for Cd. Analysis of these three metals in sediment samples reveals their presence at most stations studied. The contamination index calculation shows a moderate anthropogenic intake that requires continuous monitoring to protect the study area’s ecosystem. Crucially, the analysis of fish products revealed a lack of chemical risk concerning trace metals, known for their detrimental health effects. However, this conclusion does not dismiss the potential for subtle contamination, warranting persistent environmental surveillance. Consequently, sustained efforts in environmental monitoring are imperative to ensure the preservation of the marine ecosystem amidst escalating anthropogenic pressures.

Do salinity, total nitrogen and phosphorus variation induce oxidative stress in emergent macrophytes along a tropical estuary?

Do salinity, total nitrogen and phosphorus variation induce oxidative stress in emergent macrophytes along a tropical estuary?

Low molecular weight carbohydrate patterns of mangrove macroalgae from different climatic niches under ocean acidification, warming and salinity variation

Ocean acidification has increased due to the enhanced solubility of CO2 in seawater. Mangrove macroalgae in tropical and subtropical coastal regions can benefit from the higher availability of CO2 for photosynthesis and primary production. However, they can be negatively affected by the simultaneously occurring warming and increased salinity in estuaries. Thus, we analyzed the isolated effects of ocean acidification and the interactive effects of increased temperature and salinity on the low molecular weight carbohydrate (LMWC) contents of the mangrove red macroalgae Bostrychia montagnei and Bostrychia calliptera from Brazilian tropical and subtropical populations. Specimens from both climatic niches were tolerant to pH decreased by CO2 enrichment and enhanced their LMWC contents under increased availability of CO2. Specimens from both climatic niches also accumulated their dulcitol and sorbitol contents to cope with warming and salt stress. Nevertheless, temperature of 34 °C was lethal for tropical macroalgae, while 29 °C and 31 °C were lethal for subtropical B. calliptera under salinity of 35. Tropical and subtropical B. montagnei synthesized dulcitol (5–110 mmol kg−1 dry weight) and sorbitol (5–100 mmol kg−1 dry weight) as osmoregulatory, energy and thermal protection compounds, whereas tropical and subtropical B. calliptera synthesized mainly dulcitol (10–210 mmol kg−1 dry weight). Although digeneaside has an energy function in Bostrychia spp., it is not an osmolyte or thermal protection compound. Our data demonstrated that both tropical and subtropical Bostrychia spp. benefit from ocean acidification by CO2 enrichment, increasing their LMWC contents. However, warming and increased salinity in estuaries will be detrimental to them, even they producing protective metabolites. Multifactorial approaches are recommended to investigate whether negative effects of increased temperature and salinity nullify positive effects of ocean acidification on these Bostrychia species/populations.

Sensitivity of the thermohaline circulation during the Messinian: Toward constraining the dynamics of Mediterranean deoxygenation

During the Messinian, the sensitivity of the Mediterranean Basin to ecosystem perturbation was enhanced in response to the progressive restriction of water exchange with the Atlantic Ocean. The widespread deposition of organic-rich layers (i.e. sapropel) during the Messinian testifies the perturbation of the carbon and oxygen cycles; indeed, these sediments were deposited under conditions of oxygen starvation, presumably in response to a periodic deterioration of the thermohaline circulation strength. Disentangling the causes, the effect and magnitude of the thermohaline circulation weakening during the geological past is crucial for better constraining present and near-future deoxygenation dynamics in the Mediterranean region under the current climate warming. For this purpose, we investigate a Messinian sapropel-bearing succession cropping out at Monte dei Corvi (Ancona, central Italy) with mineralogical, petrographic, micropaleontological and stable Carbon and Oxygen isotopic analyses. We show that sapropel layers were deposited in response to an increase of the sea surface buoyancy, which hampered the thermohaline circulation and thus the oxygenation of bottom water, in turn affecting the bioturbating organisms. Within the lithological cycle, the recovery of an efficient thermohaline circulation is recorded by thin packstone layers underlying the marly limestone/marlstone, which record intense bottom currents. The marly limestone/marlstone accumulated during periods of intense primary productivity and organic carbon export to the sea bottom, which promoted bottom hypoxia but not organic matter preservation. We infer that these lithological changes resulted from variations in the Adriatic Deep Water formation system, controlled by precession-driven climatic and oceanographic changes.By integrating previously published Sea Surface Temperature (SST) with new isotopic and mineralogical data, we show that variations in Sea Surface Salinity (SSS) were the leading factor controlling sapropel deposition, minimizing the role of primary productivity. The SSTs characterizing the sapropel deposits are close to the range of those projected in the Eastern Mediterranean at the end of this century under climate warming. In this scenario, future warming will be coupled with SSS increase, which will counteract the density loss provided by temperature, making the bottom deoxygenation in the Eastern Mediterranean abysses unlikely. However, additional forcing, such as winter heat waves and eutrophication, could contribute to negatively affecting the Mediterranean oxygen balance and should be considered in model-based projections.

The Salinity of Coastal Waters as a Bellwether for Global Water Cycle Changes

AbstractWhile the global water cycle has been studied previously based on land and open ocean studies, here we use coastal satellite sea surface salinity (SSS) data to show that in global aggregate, SSS variations near coasts are strongly correlated with global water cycle variability driven by El Niño Southern Oscillation (ENSO). This is a significant finding as we demonstrate that open ocean SSS variability is not as sensitive to ENSO and global water cycle variability as the coastal oceans at interannual timescales. Aggregated global coastal SSS could therefore be used as a proxy for detection of changes in the large‐scale cycling of water between the oceans and continents. Moreover, we identify major potential “hotspots” on land and in the coastal ocean that tend to drive global coastal salinity variability, and which may consequently be most sensitive to future physical and biological impacts of water cycle changes on the coastal oceans.

Salinity impacts on a unique desalination system embedded with concentrated solar energy for cleaner production

This research comprehensively analyzed a unique solar desalination unit that operates on concentrated solar energy. The analysis primarily focused on evaluating three crucial components: the condenser, flash chamber, and brine heater. Testing was initially performed using seawater sourced from the eastern region of Saudi Arabia. Subsequently, to investigate the influence of salinity on the system performance, the device was tested under variable salinity levels ranging from 15,000 ppm to 35,000 ppm. Key parameters, including condenser temperature, brine heater temperature, and distillate production, were measured throughout the experimentation. The findings unveiled an inverse correlation between salinity and distillate production, as increasing the salinity from 15,000 ppm to 35,000 ppm resulted in a decline in distillate production. The maximum distillate achieved was 2400 ml/h at a salinity level of 15,000 ppm, corresponding to a constant feed rate of 0.2 l/min. The average energy efficiency of the brine heater was determined to be 61.9%. Moreover, the average exergy efficiencies were calculated as 81.3% for the condenser, 4.4% for the brine heater, and 44.3% for the flash chamber. Mathematical models were subsequently developed to establish the relationships between salinity and various system responses. Furthermore, performance metrics such as gain output ratio, energy utilization factor, and specific energy consumption were evaluated. The proposed system has a maximum gain output ratio of 16, a maximum energy utilization factor of 2.2, and a minimum specific energy consumption of 299.3 kWh/m3.

Modeling seasonal salinity variations in a large West African lagoon (Nokoué, Benin): Major drivers and mechanisms

Nokoué lagoon is a shallow water body connected to the Gulf of Guinea through the long and narrow Cotonou channel. The salinity dynamics in the lagoon is investigated using the 3D SYMPHONIE numerical model. We first validate the model using salinity and water level data. Simulated and observed salinity and water level variations compare well demonstrating that the reference model simulation correctly reproduces the dynamics of the lagoon. By performing several simulations with varying external forcings and freshwater fluxes, the main drivers of salinity variability in the lagoon are identified. We first focus on the salinization phase of the lagoon at the end of the tropical wet season (between November and February), and we investigate the total change in salinity and the salt fluxes involved in these variations. The high frequency salt fluxes associated with the ocean tide import salt from the ocean via the Cotonou channel to the south of the lagoon. Baroclinic fluxes, associated with the influence of salt on density and associated pressure gradient, increase this local salinity input in the south, but also play a major role in the dispersion of salt throughout the lagoon. Two rivers provide a permanent freshwater inflow in the north/ northeast of the lagoon that limits the salinization of the whole lagoon. Finally, wind-generated high frequency recirculation, partially prevents the salinisation of the North-East of the lagoon. During the desalinization period (between May and September), the lagoon salinity variations are highly sensitive to the magnitude of river inflow. At a constant river flux rate, the lagoon attains an equilibrium state in salinity. As this equilibrium is reached, both the overall salinity level and the time needed to achieve it decrease notably with higher fluxes. Beyond 100 m3 s-1, only a small area near the Cotonou channel retains higher salinity, while surpassing 500 m3 s-1 results in complete desalination of the entire Nokoué lagoon.

Can salinity variability drive the colonization dynamics of periphytic protozoan fauna in marine environments?

To investigate effects of salinity variability on colonization dynamics of periphytic protozoan fauna, a 21-day study was conducted in temperature-controlled circulation systems (TCCSs). Periphytic protozoan communities were incubated using glass slides as artificial substrata in five TCCS aquaria with a large-scale salinity gradient of 9, 19, 29 (control), 39, and 49 PSU, respectively. The colonization dynamics were observed on days 3, 5, 7, 10, 14, and 21. The colonization dynamics were well fitted to the MacArthur–Wilson and logistic model equations in colonization and growth curves in all five treatments, respectively. However, the maximum species richness and abundance were reduced, and the colonization patterns were significantly shifted in four treatments with salinity changed by 20 PSU compared to the control (29 PSU). Thus, it is suggested that the large-scale salinity variability may reduce the species richness significantly and affect colonization dynamics of periphytic protozoan fauna in marine environments.

Spatiotemporal variation in soil salinity under irrigated fields at Bochessa catchment in Central Ethiopia

AbstractSoil salinity and sodicity problems are one of the major challenges to the permanence of irrigated agriculture in Ethiopia. This manuscript, therefore, concerns its spatial and temporal variation under irrigated fields and suggests possible management options. For this investigation, eight monitoring locations were selected based on the irrigation intensity that farmers practised in the area. With each location, three irrigated farmers' fields were randomly selected for sampling purposes. Likewise, six farmers' fields from the rain‐fed system were also selected for comparison purposes. Sampling was performed at the beginning and end of each cropping season for three consecutive years from 2017 to 2019. The major physical and chemical properties of the soil were analysed in accordance with standard laboratory procedures. A linear model of two‐way analysis of variance was used to analyse parameters across time and space. The results indicated that the majority of the soil properties studied showed significant differences (p < 0.05) over time. This implies that the change is in accordance with the seasonal soil property, possibly due to irrigation practices. Similarly, approximately 90% of the soil properties studied showed noticeable differences (p < 0.05) across locations. Almost all salinity indicators showed an increasing trend in irrigated fields compared to their situation in rain‐fed fields. For instance, the electrical conductivity (EC) and exchangeable sodium percentage (ESP) values across the fields ranged from 0.54 to 0.82 dS m−¹ and 8–1%, respectively, with maximum values observed in irrigated fields. This implies that irrigation practices influence soil properties in the area. In addition, the ESP values approaching the maximum permissible limit suggest that sodicity may cause more problems than salinity in the area. Therefore, agronomic practices (e.g. residue management, deep tillage, salt‐tolerant crops and periodic fallowing), irrigation and drainage management practices, and amendments may help farmers mitigate salinity and sodicity problems in the area.

Coastal residential canals harbor distinct water quality conditions and phytoplankton community composition

As urbanization increases, many regions around the globe are seeing an increase in the number of residential canal systems along their coastlines. These canals possess unique attributes that may facilitate water quality degradation, namely shallow depths, susceptibility to urban runoff, and limited flushing. Despite this, there has been little research on the water quality and phytoplankton dynamics of these systems. In this study, water quality and phytoplankton biomass/composition were quantified once per month in the fall and winter, and twice per month in the spring and summer, over a 1-year period at three sites along a mouth-interior gradient of a canal system on North Padre Island (Corpus Christi, Texas, USA). It was hypothesized that interior canal sites would exhibit symptoms of water quality degradation more regularly than a site at the mouth, and interior canal sites would also have higher chlorophyll a and distinct phytoplankton community composition compared to the mouth. Results showed that the mouth site exhibited lower inorganic nutrient concentrations and less pronounced variability in salinity and nutrients than the interior canal sites. Chlorophyll a was 2.5-3-fold higher in the canal sites than at the mouth on average, and diatoms dominated at the mouth while a more diverse assemblage dominated at the canal sites. Episodic to persistent hypoxia was observed at the canal sites, but not at the mouth. These findings show that artificial coastal residential canal systems have distinct and less desirous water quality conditions and phytoplankton communities, pointing to a need for additional research on the attributes of canals that foster these conditions to support effective ecosystem health management efforts.

Nitrogen compounds removal from brackish water by electrodialysis at fixed electric potential and dynamic current density operations

Nitrogen (N) compounds can occur in water resources from natural and anthropogenic activities. It is ideal that these contaminants be removed before water consumption. As water quality has been affected by increased salinity and pH variation, more advanced and robust technologies such as electrodialysis (ED) can be considered for simultaneous desalination and pollutant removal. In this context, the removal of N-species (NO3−, NO2−, NH4+, and CH4N2O) from brackish water by ED was investigated for different feed water quality, considering increased salinity (0 – 10g/L NaCl) and pH variation (3 – 11), under limit current density (LCD) at fixed electric potential condition. The applied electric potential (5 – 25V) under, at, and over the LCD at fixed electric potential and dynamic current density (DCD), as a percentage of LCD (0.4 - 1.2), were analyzed to improve the process. In addition, energy efficiency in the form of specific energy consumption (SEC) and current efficiency (CE) were assessed for ED at fixed electric potential and DCD. The results showed that, at extreme pH of the feed water, the removal of NO2− and NH4+ can be affected, while NO3−was the most stable compound with pH variation. An increase in feed water salinity just slightly impacted the removal of N-compounds, due to the similar characteristics of the ions in the water. The increase in electric potential at fixed electric potential or DCD increased the removal and molar flux of N-compounds. However, operating over the LCD increased the SEC of the ED process while changes in removal were not significant. DCD procedures resulted in higher CE and shorter run time of the experiments. Therefore, ED proved to be a suitable treatment technique to produce fresh water due to the selective removal of the studied ions, especially at 15V (fixed electrical potential) and 0.8 LCD (DCD) related to removal, molar flux, and run time to achieve guidelines.

Responses of Tomato Crop and Water Productivity to Deficit Irrigation Strategies and Salinity Stress in Greenhouse

Saudi Arabia faces water scarcity and inadequate sustainable sources, particularly in agriculture, necessitating efficient irrigation water management to improve productivity amidst rising demand. The study investigated the impact of irrigation levels and water salinity on tomato plants in greenhouses, covering four irrigation levels (100%, 80%, 60%, and 40% of ETc) and three water sources (FW (0.9 dS·m−1), SW (3.6 dS·m−1) and MW (2.25 dS·m−1)). Salinity impacts crop yield, physiological responses, and fruit quality. The photosynthesis, stomatal conductance, transpiration, and chlorophyll content decrease with MW and SW, negatively affecting morphological characteristics. For MW, it was recommended to apply 60% deficit irrigation with a yield of 98 kg·ha−1, and water productivity (WP) improved to 21.93 kg·m−3 compared to 13.65 kg·m−3 at full irrigation (FI). In SW, 80% irrigation was suggested, as there was no significant difference in yield compared to FI. For FW, 60% deficit irrigation produced the best water conservation (104.58 kg·ha−1 yield and 23.19 kg·m−3 WP), while FI produced the highest yield per unit area (123.48 kg·ha−1 yield and 16.51 kg·m−3 WP). Nonetheless, greater water and salinity stress was associated with increased fruit quality measures such as total acidity, vitamin C, and soluble solids. The results show that implementing deficit irrigation with salinity strategies in greenhouse tomatoes could improve crop adaptability, yield, and water productivity in the face of water scarcity and salinity variability.

Interannual Variability of Salinity in the Chukchi Sea and Its Relationships with the Dynamics of the East Siberian Current during 1993–2020

The interannual features of the salinity in the Chukchi Sea during the ice-free period of a year are investigated on the base of Soil Moisture Active Passive (SMAP) satellite measurements and GLORYS12v1 reanalysis data. Analysis of salinity measurements revealed two types of Bering Summer Waters (BSW) propagation: “western” and “eastern”. The first is characterized by the penetration of Pacific waters into the northwest part of the sea, as well as the propagation of BSW to 180°W and 72.5°N. During the “eastern” type, salty waters are pressed to the eastern part of the shelf. Their area decreases and the northern boundary of the BSW area shifts to 174–176°W. Areas with low salinity, ~29 psu, are observed in the western part of the sea. Our study reveals that the formation of these types is affected not only by the inflow of Pacific waters through the Bering Strait but also by the East Siberian Current (ESC). Both factors are related and lead to correlated changes in the salinity of the Chukchi Sea waters. ESC carries Arctic freshwaters from west to east and leads to a decrease in salinity in the western part of the sea. At the same time, southward ESC caused the blockage of the northward currents in the Bering Strait and a decrease in the influx of saline Pacific waters in the southern part of the Chukchi Sea. The intensification of ESC occurred in 1994, 2002, 2012, and 2016, when the volume transport of ESC increased by approximately 0.2 Sv, while the influx through the Bering Strait decreased. As a result, in the years with intense ESC, the spatial structure of the salinity of the Chukchi Sea changed significantly and the shelf-averaged salinity decreased by 0.3–0.5 psu.

Sea Ice‐Driven Variability in the Pacific Subantarctic Mode Water Formation Regions

AbstractSubantarctic Mode Water (SAMW) forms north of the Subantarctic Front, in regions of deep winter mixed layers, and is important to the absorption and storage of anthropogenic CO2 and heat. Two SAMW pools exist in the Pacific, a lighter Central mode (CPSAMW), and a denser Southeast mode (SEPSAMW). Both have experienced significant interannual variability in thickness and properties in recent years. We compute mixed layer temperature and salinity budgets for the two SAMW formation regions, to determine the relative contribution of processes driving variability in the properties of mixed layers that subduct to form SAMW. The dominant drivers of temperature and salinity variability are shown to be surface fluxes, horizontal advection, and entrainment of deeper water. Salt advection into each SAMW formation region is found to be strongly correlated with changes in sea ice area in the northern Ross Sea, with lags of up to 2 years. Further correlation is found between meridional salt advection in the southeast Pacific formation regions, and sea ice area in the northern Amundsen/Bellingshausen seas, suggesting that freshwater derived from sea ice melt reaches the SEPSAMW formation region within 6 months. In 2016, strong advective freshening of the SEPSAMW formation region, linked to increased winter sea ice in the Amundsen/Bellingshausen seas, led to anomalously fresh mixed layers. However, a regime change in Antarctic sea ice in 2016 resulted in a subsequent lack of the usual advective freshening in the SEPSAMW formation region, driving increased salinity of the mixed layer the following year.

Otolith biochronology for the long-term reconstruction of growth and stock dynamics of fish

Long-term biological time series are essential to evaluate previous responses of organisms to alterations in the environment. Biochronological methods based on archival fish otoliths allow setting such time series, but their predictive potential as proxies of past environmental conditions is still underexploited. In this study, we reconstructed growth variation in European sprat (Sprattus sprattus) in the Baltic Sea from 1956 to 2020 based on measurements of the archived otoliths. We used otolith annual increment widths as a proxy of fish somatic growth. We showed significant negative relationships between sprat growth and sprat spawning stock biomass (SSB) associated with strong intraspecific competition for limited food resources. We also identified a link between sprat growth and water salinity—indicator of the ecosystem's hydrological situation. For the first time, we estimated the SSB prior to the period of available historical data based on the otolith-derived information on the past growth variation. This estimation was based on the strong relationships between SSB and fish growth, complemented with temperature and salinity variables as predictors (R2 = 0.62). A model trained on at least 40 years of data from the more recent past allows us to robustly back-estimate SSB. This study provides new multidecadal data, giving insights into environmental factors affecting the growth of Baltic sprat, and demonstrates the potential of otolith-based biochronology for the provisioning of independent indices of the historical fish stock size. The proposed methodological approach broadens the portfolio of possible applications of the biochronology time series to indicate past changes in the aquatic environment.Graphical abstract

Pacific‐Driven Salinity Variability in the Timor Passage Since 1777

AbstractSalinity in the Indonesian seas integrates regional oceanographic and atmospheric processes, such as Indonesian Throughflow (ITF) and monsoon rainfall. Here we present a multicentury (1777–1983) δ18O coral record from Nightcliff Reef, located in the Timor Passage off the coast of northern Australia, which we use to infer local salinity change. We show that Australian monsoon rainfall and ITF influence salinity at the study site. These reconstructed salinity changes in the Timor Passage correlate with changes in Pacific sea surface temperature (SST) modes, including the El Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). While environmental stress creates challenging conditions for coral growth, this record particularly tracks the central Pacific signature of ENSO‐driven interannual variability, in agreement with reconstructions of rainfall across northern Australia. The strength of interannual variance in the record follows fluctuations in other local ENSO‐sensitive rainfall reconstructions, demonstrating a strong regional ENSO signature. However, this regional pattern differs from variance in composite ENSO reconstructions, suggesting that the multi‐site nature of these reconstructions may create biases. Salinity variability on decadal and longer time scales occurs throughout the record. Some of these oscillations are consistent with other ITF‐sensitive coral records. Our new salinity record adds a strongly Pacific‐sensitive record to the existing suite of regional paleoclimate reconstructions. Relationships among these records highlight the complexity of salinity in the Indonesian seas and the controls on its variability.

Effect of Predisolved Natural Gas on CO2 Solubility in Water With Various Salinities at Reservoir Conditions

Dissolution of CO2 in saline waters is considered one of three main CO2 trapping mechanisms, along with structural/stratigraphic trapping and mineralization. CO2 can dissolve in fresh/saline water under typical reservoir pressure and temperatures. Its solubility is dependent on pressure, temperature, and salinity. CO2 solubility studies typically consider saline water or fresh water as a liquid without any predissolved gases. The reality is formation water may contain appreciable dissolved gases for all pressure and temperature conditions. An example of gas-water ratio (GWR) can be ~1 scf/stb for formation water in an oil reservoir and ~5 to 6 scf/stb for a deep saline aquifer. Therefore, it is essential to quantify the effect of brine salinity on CO2 solubility in “live” saline waters. Just as “live” oil denotes reservoir oil that contains solution gas, we define “live” brine as saline water that includes dissolved gases. Conversely, “dead” brine refers to saline water devoid of any dissolved gas content. Two sets of experiments were conducted under typical reservoir conditions. The first set of experiments evaluated the CO2 solubility in live formation water. The second set of experiments evaluated how variation in the live brine salinity affected CO2 solubility. These experiments involved 1) synthesis of the brine, 2) synthesis of natural gas mixture, 3) recombination of live formation water with a natural gas mixture and transfer into a high-pressure and high-temperature pressure-volume-temperature (PVT) visual cell, 4) CO2 addition to the PVT cell, and 5) bubblepoint pressure determination within the PVT cell. The results showed that CO2 solubility in live formation water is significantly less than that in “dead” water under reservoir conditions. In addition, the brine salinity affects CO2 solubility in live formation water by further reducing CO2 solubility with increasing live brine salinity. As the brine salinity increases, very little CO2 can be dissolved in the live brine once it reaches a certain solubility. An understanding of CO2 dissolution in live saline water is essential for future CCUS evaluation and execution.

Spatiotemporal Variability of Rainfall and Surface Salinity in the Eastern Pacific Fresh Pool: A Joint In Situ and Satellite Analysis During the SPURS‐2 Field Campaign

AbstractWe perform a statistical characterization of the 2016–2017 SPURS‐2 field campaign in situ data and coincident satellite data spanning 8°–12°N, 120°–130°W to quantify the spatial and temporal scales of variability of rain and near‐surface salinity in the Eastern Pacific Fresh Pool. Observations of rain rate and near‐surface to surface salinity are obtained from ships, moorings, autonomous platforms, and satellite remote sensing: Integrated Multi‐satellitE Retrievals for GPM (IMERG); and Soil Moisture Active Passive (NASA SMAP L3 V5). The integral length and time scales of rain and near‐surface salinity vary seasonally. In the rainy season (August–October) when the Intertropical Convergence Zone (ITCZ) migrates over the SPURS‐2 study site, the integral time scales of rain were about 30–60 min and those of near‐surface salinity were closer to that of the rain, 1–2 days, indicating forcing by rain. Meanwhile, the zonal integral length scale of in situ near‐surface salinity was twice as large as the meridional scale (50 vs. 20 km), consistent with the ITCZ's zonally‐propagating and ‐organized rain features. The magnitude and seasonal variation of the sea surface salinity integral time scale were not captured by SMAP since the rainy ITCZ‐period scales were smaller than SMAP resolution (70 km, 8‐day running mean). In the dry season (February–May), the in situ rain integral time scale reduced to less than 30 min while that of the near‐surface salinity increased to 1–5 days, the ocean mesoscale. IMERG overestimated the rain integral time scale by a factor of two to ten in both seasons.