Low Salinity Research Articles

Seasonal Phytoplankton Characteristics Related with Region-Specific Coastal Environments in the Korean Peninsula

The seasonal dynamics of phytoplankton communities in Korean coastal waters (KCWs) are influenced by complex interactions between ocean currents and nearshore human activities. Despite these influences, the understanding of seasonal phytoplankton changes and their environmental relationships in KCWs remains limited. We investigate the influence of the distinct characteristics of the three seas surrounding the KCWs (the Yellow Sea, the South Sea, and the East Sea) on seasonal phytoplankton communities based on field surveys conducted at 23 stations between 2020 and 2021. The East Sea exhibited higher winter temperatures due to the Jeju and Tsushima warm currents, while summer temperatures were lower compared to the other regions, highlighting the role of currents and deeper oceanic waters. The Yellow Sea showed significant freshwater influence with low salinity levels from major rivers, contrasting with the higher salinity in the East Sea. These differences led to a disparity in the productivity of the two regions: the highest value of Chl. a was observed to be 6.05 µg L–1 in the Yellow Sea in summer. Diatoms dominated in nutrient-rich conditions, particularly in the Yellow Sea, where they comprised up to 80–100% of the phytoplankton community in summer, winter, and spring. PCA analysis revealed positive correlations between diatoms and Chl. a, while cryptophytes, which thrive in the absence of diatom proliferation, showed no such correlation, indicating their opportunistic growth in nutrient-limited conditions. This study highlights the significant impact of region-specific hydrographic factors on phytoplankton communities in KCWs, with diatoms dominating in summer and cryptophytes and dinoflagellates showing seasonal and regional variations. Understanding these dynamics is crucial for predicting phytoplankton bloom dynamics and their ecological implications in coastal ecosystems.

Behind the Loss of Salinity Resistance during Domestication: Alternative Eco-Physiological Strategies Are Revealed in Tomato Clade

Salinity stress impairs growth and physiological performance in tomato, which is one of the most economically important vegetables and is widely cultivated in arid and semi-arid areas of the world. Plant landraces, which are heterogeneous, local adaptations of domesticated species, offer a unique opportunity to valorize available germplasm, underpinning the productivity, resilience, and adaptive capacity of staple crops in vulnerable environments. Here, we investigated the response of fully mature tomato plants from a commercial variety, an ancestral wild relative, and a landrace under short-term salinity exposure, as well as their ability to recover upon cessation of stress. The heterogeneous panel evaluated in this study revealed different adaptative strategies to cope the stress. Our data highlighted the ability of the tomato clade to handle low and intermediate salinity stress for short-term exposure time, as well as its capacity to recover after the cessation of stress, although inter- and intraspecific variations in morphological and physiological responses to salinity were observed. Overall, the landrace and the wild type performed similarly to control conditions under low salinity, demonstrating an improved ability to maintain ionic balance. In contrast, the commercial genotype showed susceptibility and severe symptoms even under low salinity, with pronounced reductions in K+/Na+ ratio, PSII photochemical efficiency, and photosynthetic pigments. This research confirmed that improved salt tolerant genotypes can lead to substantial, positive impacts on horticultural production. While the salt tolerance mechanism of domesticated tomato was efficient under mild stress conditions, it failed at higher salinity levels.

Metabolic fingerprints and immune response of silverlip pearl oysters (Pinctada maxima) under low salinity event

Marine ecosystems are prone to hyposalinity events due to rainfall and freshwater inflow, which has led marine bivalves to develop mechanisms to adapt to salinity fluctuations over a long period of evolution. This study conducted a comprehensive assessment to examine the physiological impact of a low salinity event on Pinctada maxima, which included measure- ments of haemolymph electrolytes, haemocytes functions, and non-targeted metabolomics analyses. A total of 92 metabolites were detected in the gill tissue of P. maxima. Six hours after exposure, low salinity stress impacted five metabolomic pathways, with succinic acid and alanine being highly upregulated. However, the electrolyte and the measured immune response were unaffected at that sampling time. After 24 h of exposure to low salinity conditions, a significant decrease in the concentrations of key electrolytes in the haemolymph was observed, including Na+, Cl−, K+, and Ca2+. Furthermore, the immune responses of the pearl oysters were affected by hypo-salinity stress. Additionally, the total haemocyte count decreased significantly, and some important immune functions, such as the phagocytosis capacity and the intracellular oxidative activity were suppressed. After 72 h of exposure to low salinity, an increase in alanine and succinic acid levels indicated the onset of anaerobic metabolism. The prolonged hyposalinity exposure (72 h) impacted nine metabolomic pathways. The downregulation of adenosine suggested the impairment of the cyclic adenosine monophosphate (cAMP) pathway, which inhibits ambient inorganic ions entering the gill cells. This study identified potential metabolic biomarkers such as succinic acid in oysters exposed to hyposalinity stress.

Maize auxin response factor ZmARF1 confers multiple abiotic stresses resistances in transgenic Arabidopsis.

Prolonged exposure to abiotic stresses causes oxidative stress, which affects plant development and survival. In this research, the overexpression of ZmARF1 improved tolerance to low Pi, drought and salinity stresses. The transgenic plants manifested tolerance to low Pi by their superior root phenotypic traits: root length, root tips, root surface area, and root volume, compared to wide-type (WT) plants. Moreover, the transgenic plants exhibited higher root and leaf Pi content and upregulated the high affinity Pi transporters PHT1;2 and phosphorus starvation inducing (PSI) genes PHO2 and PHR1 under low Pi conditions. Transgenic Arabidopsis displayed tolerance to drought and salt stress by maintaining higher chlorophyll content and chlorophyll fluorescence, lower water loss rates, and ion leakage, which contributed to the survival of overexpression lines compared to the WT. Transcriptome profiling identified a peroxidase gene, POX, whose transcript was upregulated by these abiotic stresses. Furthermore, we confirmed that ZmARF1 bound to the auxin response element (AuxRE) in the promoter of POX and enhanced its transcription to mediate tolerance to oxidative stress imposed by low Pi, drought and salt stress in the transgenic seedlings. These results demonstrate that ZmARF1 has significant potential for improving the tolerance of crops to multiple abiotic stresses.

Novel approach evaluating powdered raw and hydrothermally treated syenite as stonemeal for tropical environments: Potential effects on groundwater quality and agricultural suitability

Soluble fertilizers, particularly potash, are often prohibitively expensive or unavailable in Africa. Consequently, alternatives such as powdered silicate rocks, both raw and hydrothermally treated, are being explored as potential solutions, especially for acidic tropical soils. This study investigates the possible impacts of these rocks (syenite) on groundwater quality, which is a critical factor for agricultural activities. The powdered raw material underwent chemical and mineralogical characterization, including X-ray fluorescence and X-ray diffraction, followed by quantitative evaluation of materials by scanning electron microscopy. Both raw and 46 hydrothermally treated materials were subjected to sequential leaching cycles (1, 24, and 192 h) using deionized water, and the resulting leachates were analyzed by inductively coupled plasma atomic emission spectroscopy. Parameters such as electrical conductivity, total dissolved solids, soluble sodium percentage, sodium adsorption ratio, magnesium hazard, Kelly's ratio, and permeability index were also evaluated. Results from the 47 leachates indicated that 64 % of the samples exhibited excellent to acceptable water quality for irrigation purposes across all parameters. Conversely, 6 % to 13 % fell into the doubtful category, and 2 % to 24 % were classified as unsuitable. Consistency index and ratios of approximately 0.07 and 0.042, respectively, were determined using multi-criteria decision analysis (analytic hierarchy process: AHP), confirming the coherence of the decision and pairwise comparison matrix. The weighted coefficients for each criterion ranged from 0.06 to 0.2. Consequently, the optimal sample (Treatment 23) was identified, showing a hydrothermal temperature of 176 °C, a time of 3.9 h, a normality of 4.62, and a liquid-solid ratio of 0.24. This treatment met all high-water quality standards, including low salinity and sodium hazard, as corroborated by the US salinity laboratory and Wilcox diagrams. Furthermore, due to their nutrient release, low concentration of toxic elements, and effective buffering capacity (pH ∼ 10.6), these powdered syenites are suitable for application in acidic soils.

Decoupling of Cu and Zn in sediment-hosted base metal deposits: Evidence from LA-ICP-MS analyses of fluid inclusions and trace elements in minerals at Baiyangping, China

Copper and lead–zinc mineralization in basinal rocks worldwide commonly shows distinct spatiotemporal zonation. The Baiyangping deposit in the Lanping Basin, southwest China, is a large sediment-hosted polymetallic deposit that shows clear and pronounced zoning of Cu versus Pb-Zn mineralization. Here, we analyzed trace elements in pyrite and sphalerite and fluid inclusions in sphalerite, celestine, quartz, and dolomite to seek insights into the origins of the ore-forming fluids and the processes that govern the separation of Cu- from Zn-rich ores. We show that while the later Zn-rich mineralization is characterized by fluid inclusions showing typical hallmarks of basinal brine composition (low homogenization temperature < 230 °C, high salinity > 20 wt% NaCl eq., dominated by Na-K-Ca-Mg chlorides), the earlier Cu-rich mineralization shows markedly distinct composition that more closely resembles deeply-circulated water that has equilibrated with crystalline basement rocks (higher homogenization temperature of 210–280 °C, variable but lower salinity of ∼ 5–15 wt% NaCl, dominated by Na-K-Li chlorides). Pyrites formed during the earlier Cu-rich stage show elevated Cu, Co, Sb and Zn, while pyrites formed during the later Pb-Zn stage are more enriched in As, Pb and Mn. We interpret that the earlier-formed Cu-rich ores were deposited by deeply sourced fluids that ascended along basement-penetrating reverse faults, whereas the later Zn-rich ores were formed by subsequent circulation of fluid from within the basin, whose flux was promoted by shallower strike-slip faults. Hence, the two ore types reflect discrete pulses of chemically distinct hydrothermal fluids. We suggest that the evolving structural controls and fluid pathways during prolonged ore formation allowed sequential pulses of fluids that had acquired different metal budgets by equilibration with different sources. We suggest that this type of two-step process may be more common in sediment-hosted base metal deposits than single-fluid cooling sequential order of precipitation.

Reversibility of seawater intrusion in a coastal aquifer: Insights from long-term field observation and numerical modeling

It is essential to understand basis processes affecting the reversibility of seawater intrusion (SWI) and the related timescale after groundwater pumping stopped for coastal groundwater management. Groundwater salinity variations presented by previous studies showed a fast SWI process and the following seawater retreat (SWR) process indicated by overall salinity decrease in the coast karst aquifer in the Dalian Peninsula, northeast China. Cross-sectional variable-density flow and transport simulations using equivalent porous medium (EPM) model, dual-domain (DDM) model and the EPM with a single discrete feature representative of conduit flow (EPM-DF) are conducted to understand the SWI reversibility related to the characteristics of the flow system, including aquifer parameters and seaside boundary conditions. Large dispersity combined with a low salinity concentration at the sea boundary are necessary in the EPM and DDM models to produce a fast SWI and low salinity concentration as observed. The enhanced dispersion in the DDM model enhances the mixing in the transition zone (TZ) and produces more obvious seasonal variation but longer SWR process compared to the EPM model. The EPM-DF model produces significant salinity seasonal variation during the SWI process and a fast decrease in the SWR process. The overall fast system response but low peak concentration during the SWI might be attributed to the highly heterogeneous characteristics of the karst aquifer system, which produces a wide front edge of TZ as observed. The dispersion-dominated EPM and DDM models produced higher degree of SWI reversibility compared to the EPM-DF model, as indicated by the weaker lag effects between groundwater levels and salinity concentration. Moreover, the SWI reversibility may arise not only from the heterogeneous characteristics of the karstic aquifer system but also from the rate for rise in the inland groundwater level during the seasonal variation cycle. An overall SWR process can be divided into two stages: the first stage with rapid decrease in salinity concentration but small changes in toe associated with TZ widening and the second stage with rapid toe retreat during aquifer flushing. The flushing of the brine leakage from the solar salt field may extend the SWR process. Considering this relatively longer water quality response time than the time span in general groundwater management plans, a reasonable objective and how maintain the hydraulic head during the SWI controlling have been of a great concern to the coastal groundwater management.

Seasonal and Inter-annual Variability in the East of the Sea of Marmara Water Masses by Temperature and Salinity Time Series

This study mainly aims to examine the relationship between oceanographic properties and climate change in the conjunction of the Istanbul Strait (IS), specifically in the east of the Sea of Marmara (SoM) via evaluating observational temperature and salinity profiles at six stations with monthly atmospheric pressure and air temperature during the period of 1997-2010. The annual cycle of temperature and salinity of the upper and lower layers in the east of SoM have strong seasonal variation: The upper layer temperature rises during summer while decreases in winter. Conversely, the lower layer temperature is higher in winter compared to spring and summer. Additionally, salinity levels in the upper layer are higher in winter and lower in summer, whereas in the lower layer, the pattern is reversed, with lower salinity in winter and higher salinity in summer. In this context, linear trend analyzes are calculated by using monthly time series of temperature and salinity and compared with the trends of atmospheric conditions and the surrounding seas. The average temperature trend in the east of the SoM is increase of 0.067°C/y in the upper layer and increase of 0.028°C/y in the lower layer during this period. The salinity trend is increase of 0.105 psu/y in the upper layer and increase of 0.012 psu/y in the lower layer. The air temperature trend is increase of 0.086°C/y, and the air pressure trend is decrease of 0.034 mbar/y. These values closely align with those observed in the surrounding seas. The air temperature and upper layer temperatures are consistent with each other in terms of both long-term series and trend values.

Unravelling CH4 and N2O dynamics in tidal wetlands using natural abundance isotopes and functional genes

Tidal wetlands are one of the major sources of CH4 and N2O in natural systems to the atmosphere; yet we still lack insights into the impact of their biogeochemical dynamics on the emissions of these greenhouse gases (GHGs). Here, we investigated the CH4 and N2O sources in four tidal wetlands ranging from freshwater to polyhaline with a focus on their production pathways. By using natural abundance isotopes and functional marker genes, we found that salinity level, sediment moisture content, quantity and quality of organic carbon (OC) and nutrients were major drivers of the wetland CH4 and N2O emissions. As the salinity levels decreased in the tidal wetlands, both the labile nature and concentration of nutrients and OC increased. These conditions favored methanogenesis as indicated in the abundance and expression of mcrA and the CH4 emissions from the freshwater wetland. Conversely, higher salinity depressed organic matter decomposition rates and microbial activities, causing much lower CH4 production in the saline wetlands. Isotope mapping revealed that denitrification contributed mainly to wetland N2O emissions (80–90%), reflected in the strong expression of denitrifier marker genes nirS, nirK, and nosZ and low nosZ:nir ratio. Nitrification played an important role in wetland N2O emissions at high NH4+ and low salinity levels. This condition was the case in the freshwater wetland – the strongest N2O emitter – where we found the highest NH4+ concentrations and the most abundant and expressed nitrifier marker genes amoA AOA and amoA AOB. Methanogen and denitrifier marker genes were more abundant and expressed at the surface layer compared to the subsurface layer, implying the presence of methane and denitrification paradoxes in the tidal wetlands. This study paves a way for the coupling of isotope and functional gene analyses to deeply explore GHG formation pathways and responsible microbial activities in dynamic wetland systems.

Low salinity water flooding: estimating relative permeability and capillary pressure using coupling of particle swarm optimization and machine learning technique

The reservoir’s properties are required for proper reservoir simulation, which also involves uncertainties. Experimental methods to estimate the relative permeability and capillary pressure data are expensive and time-consuming. This study aims to determine the relative permeability and capillary pressure functions of a sandstone core in the presence and absence of clay during low-salinity water floods. The data were provided by automatic history matching the results from previously lab-reported studies through coupling a simulator with the particle swarm optimization algorithm. Correlations were proposed using multiple-linear regression for relative permeability and capillary pressure parameters at low-salinity conditions. They were validated against experimental results of no clay and clayey formation with regression of 95% and 97%. To assign one curve of relative permeability and capillary pressure to the grid cells of the simulator, averaging techniques were implemented. The effect of salinity and clay content on the obtained curves was investigated. Changing salinity from 42000 to 4000 ppm, the reduction in water relative permeability appeared to be higher than the oil relative permeability increment. Moreover, a noticeable shift in the relative permeability curves toward the highest saturations related to the clay content was observed. The proposed hybrid method could be a suitable tool to estimate the relative permeability and capillary pressure functions of the water-based EOR methods.

Effect of salt-alkali stress on seed germination of the halophyte Halostachys caspica

The increasing global phenomenon of soil salinization has prompted heightened interest in the physiological ecology of plant salt and alkali tolerance. Halostachys caspica belonging to Amaranthaceae, an exceptionally salt-tolerant halophyte, is widely distributed in the arid and saline-alkali regions of Xinjiang, in Northwest China. Soil salinization and alkalinization frequently co-occur in nature, but very few studies focus on the interactive effects of various salt and alkali stress on plants. In this study, the impacts on the H. caspica seed germination, germination recovery and seedling growth were investigated under the salt and alkali stress. The results showed that the seed germination percentage was not significantly reduced at low salinity at pH 5.30–9.60, but decreased with elevated salt concentration and pH. Immediately after, salt was removed, ungerminated seeds under high salt concentration treatment exhibited a higher recovery germination percentage, indicating seed germination of H. caspica was inhibited under the condition of high salt-alkali stress. Stepwise regression analysis indicated that, at the same salt concentrations, alkaline salts exerted a more severe inhibition on seed germination, compared to neutral salts. The detrimental effects of salinity or high pH alone were less serious than their combination. Salt concentration, pH value, and their interactions had inhibitory effects on seed germination, with salinity being the decisive factor, while pH played a secondary role in salt-alkali mixed stress.

Elemental geochemistry of Cretaceous deposits in the Dahomey Basin (Nigeria): Implications for paleoclimatic and paleoenvironmental reconstructions

The Dahomey Basin, located in southwestern Nigeria, is an energy-rich frontier basin with sedimentary successions consisting of both (onshore) terrestrial and (offshore) marine deposits. Since the discovery of several bitumen seeps, tar sands, and oil and gas shows offshore the basin and the successful production of the Aje Field, the basin has gained immense interest from academia and industry. Nevertheless, surface and subsurface research focusing on paleoclimatic conditions, primary productivity, anoxic conditions, paleowater depth, and hydrodynamic influence in the Dahomey Basin is less documented. To reconstruct paleoenvironmental conditions, subsurface data from the Araromi-Obu (A1) and Idiobiolayo (A15) cores were used. The average chemical index of alteration (CIA) values ranging from 63.01 to 94.88 reflect varying degrees of weathering intensity in the sediment source area of the Cretaceous Araromi Formation. These values show a transition from relatively low to considerably high degrees of weathering in the source region of the Araromi Formation. The analysis of CIA values and Ga/Rb, Sr/Cu, Sr/Ba, Ca/Al, and 100*Mg/Al ratios suggests that the Araromi Formation was deposited in a brackish to marine environment.Furthermore, chemical alteration-sensitive geochemical indicators revealed prevailing warm, humid tropical climates during the late Cretaceous period, with likely minor arid intervals. In addition, the geochemical markers used (Ba/Al, U/Th, Ni/Co, authigenic uranium (Uau), P/Ti, and [(Fe2O3 + CaO + MgO)/(SiO2 + Al2O3)] indicate poor paleoproductivity for the Araromi Formation deposited in an oxygen-rich marginal to shallow marine environment. The upper Cretaceous period was characterised by fluctuating hydrodynamic circulation, with a weak hydrodynamic regime in core A1 and transitioning to strong hydrodynamic conditions in core A15. The inferred paleowater depth corresponds to the salinity measurements, with the A1 core displaying elevated salinity, indicating a greater depth compared to the A15 core, which was deposited in a shallower environment and displays lower salinity.

High-resolution water temperature and salinity evolutions and associated drivers of the North Yellow Sea during the Late-Holocene

The mud deposit areas on continental shelf have developed in a relatively steady sedimentary condition with high sedimentation rates, thus rendering them ideal regions for exploring high-resolution paleo-sedimentary environment records. Since the sedimentary environment of the continental shelf is subject to the compound influence of multiple factors, the reconstruction of water salinity and temperature and comprehensive analysis of their response to global climate change remains challenging. Therefore, the present study characterized water salinity and temperature of the North Yellow Sea (NYS) using proxies, such as ratios of halogen elements of sediments and stable isotopic compositions of benthic foraminifera, and found the halogen elements of Cl in sediments was good proxy for water salinity. The evolutions of water salinity and temperature of the NYS for the past 3000 years were reconstructed, while the evolution stages and drivers of the sedimentary environment were explored. From approximately 3000 cal yr BP, the sea bottom salinity and temperature of the NYS were found to follow the same evolution trends predominantly consisting of the three stages: relatively low seawater salinity and temperature during 3000−2000 cal yr BP; relatively high seawater salinity and temperature during 2000−460 cal yr BP; and rapid changes of seawater salinity and temperature since 460 cal yr BP. The changes in seawater salinity and temperature of the NYS were largely driven by the East Asian winter monsoon (EAWM) as well as the influence of the Kuroshio Current. As the EAWM fluctuated, changes occurred in the flux of low temperature, low salinity coastal current water into the Yellow Sea, with concomitant changes in bottom temperature and salinity. Strengthening of the Kuroshio Current promoted the development of the Yellow Sea Warm Current, while the influx of warm, salty water into the Yellow Sea influenced the respective sea region. The abrupt global climate changes such as the “Little Ice Age” and the Medieval Warm Period first affected the East Asian monsoon, followed by the respective sea region.

Freshwater discharge drives latitudinal changes of phytoplankton composition on the continental shelf off Chilean Patagonia

A high-resolution survey of distribution, abundance and composition of phytoplankton was carried out for the first time in surface waters of the continental shelf off Chilean Patagonia (41–48°S). An Imaging FlowCytobot was used along the survey track to record phytoplankton in the size range of 10–120 μm during the austral spring of 2018. Phytoplankton community structure was complemented with continuous underway measurements of temperature and salinity, and physicochemical parameters of the water column at 35 oceanographic stations. Our results evidenced two main macrozones with distinctive phytoplankton assemblages delimited latitudinally at ~45°S. The northern macrozone was characterized by higher surface temperature and salinity, Si:N ratio > 1, diatoms of the genera Thalassiosira and Chaetoceros, and dinoflagellates accounting for over 70% of the total abundance. The southern macrozone, with lower surface temperature and salinity and Si:N ratio < 1, was characterized by members of the genera Guinardia, Lauderia and Cerataulina, representing over 60% of the total phytoplankton. These changes were attributable to the strong influence of freshwater at latitudes higher than 45°S and the enhanced discharge of meltwaters from Patagonian icefields in the area of the Taitao Peninsula and the Gulf of Penas (47–-48°S). Fresh and cold waters impacted the water column stratification and the availability of dissolved silicic acid with potential effects on phytoplankton composition and diatom cell silicification and, thus, on carbon exportation. Our estimations of phytoplankton carbon were comparable to those observed in Patagonian fjords and the highly productive upwelling ecosystem of central Chile. We suggest that the continental shelf off Patagonia can contribute significantly to strengthen the biological carbon pump through the synthesis, exportation, and sequestration of phytoplankton-based organic carbon in the southeastern Pacific Ocean.

The effects of diet, salinity and temperature on HUFA accumulation in Artemia

Artemia nauplii is an important live food item for marine fish and crustaceans. However, the HUFA content of Artemia from different origins varies greatly and is generally low. Compared with other species or strains, Artemia cysts in Tibet salt lakes have very high HUFA content, which may be related to their unique living conditions. This study determined the effects of dietary HUFA (P. tricornutum and C. zofingiensis), salinity (4%, 8%, and 12%), and temperature (14 °C, 19 °C, and 24 °C) on the HUFA accumulation of Lagkor Co Artemia tibetiana after 14-day culture, in comparison with Great Salt Lake Artemia franciscana. The results showed that the HUFA profile of Artemia was closely related to the dietary HUFA level, and the low temperature and low salinity could significantly increase the ARA, EPA, and DHA content. PCA results showed that the fatty acid distribution patterns of the two Artemia species were mostly affected by dietary fatty acids, which were greater than those of temperature, salinity, and Artemia species. RNA-seq analysis and qRT-PCR verification revealed that low temperature and low salinity could promote the gene expression of fatty acid binding protein gene, long chain fatty acid elongase, and desaturase, suggesting these genes may be involved in the process of HUFA accumulation in A. franciscana. In conclusion, diet is a key factor affecting HUFA accumulation in Artemia, while low temperature and low salinity led to higher HUFA retention. The findings of this study provide a reference for revealing the mechanism of HUFA synthesis and metabolism of Artemia, and to develop the Artemia products with high HUFA content through manipulation of culture conditions.

Analysis of the signal molecular regulation mechanism of anammox biofilm/particles in low salinity environment from the point of view of sludge structure cohesion

The application of anaerobic ammonium oxidizing (anammox) in the treatment of municipal wastewater with low matrix has always been challenging. At the same time, the substitution of seawater and the extensive use of deicing salt in winter increase the salinity of municipal wastewater with low matrix, which increases the difficulty of treatment. This study focused on the performance of anammox biofilm (AM) and granular sludge (AG) in salinity environment from the point of view of signal molecular regulation and sludge structure cohesion. AM could adapt and form a stable biofilm after acclimation at 0.6 % salinity, while AG collapsed due to the decrease of particle size and the sharp decrease of the abundance of anammox bacteria. AM protected anammox-related genus such as Candidatus Kuenenia and Ignavibacterium by releasing more endogenous C8-HSL and C12-HSL to ensure stable nitrogen removal. Endogenous C8-HSL and C12-HSL stabilize the anammox process by enhancing EPS to increase water output and increasing COD consumption by some heterotrophic bacteria, respectively. The modularization of the microbial community network of AM was 0.937. the rich microbial diversity improves the salinity impact performance of AM. The microorganisms responsible for nitrogen metabolism, sulfur metabolism, and protein export in AM were significantly higher than AG when the salinity reached 0.6 %. In conclusion, this research illustrated that the AM could maintain good nitrogen removal performance in the mainstream municipal low-salt wastewater, clarified the mechanism of signal molecules regulating and promoting the anammox process, and provided theoretical support for the application of anammox in mainstream engineering.

Garlic (Allium sativum L.) Invertase Genes: Genome-Wide Identification and Expression in Response to Abiotic Stresses and Phytohormones

Invertases are involved in plant growth, development, and stress adaptation; however, invertase-encoding genes have not yet been reported in Allium species. In this study, we identified 23 invertase izogenes in garlic (Allium sativum L.): 11 encoding putative neutral/alkaline (AsN/AINV1–11) and 12 acid (6 cell-wall—AsCWINV1–6 and 6 vacuolar—AsVINV1–6) enzymes. Among them, AsN/AINV1, 3, 8–10, AsCWINV2–5, and AsVINV2–6 showed significant transcription in garlic organs (roots, bulbs, pseudostems, leaves, sprouts, and reproductive parts) in a tissue-specific manner, whereas the AsN/AINV4–6, 11, AsCWINV1, 6, and AsVINV1 genes had weak or no detectable expression. Gene promoters contained nine, nine, and sixteen hormone-, stress-, and light-responsive cis-regulatory elements, respectively, and fifteen sites related to transcription factor binding and plant development. Expression analysis revealed that 12 invertase genes strongly transcribed in the roots of A. sativum cv. Ershuizao showed differential expression in the roots and leaves of A. sativum cv. Sarmat exposed to abiotic stresses (low temperature, high salinity, and drought) and phytohormones (abscisic acid and methyl jasmonate), which was significantly correlated with glucose, fructose, and sucrose contents. Our results should further functional analysis of invertases from Allium crops and contribute to the breeding of stress-tolerant varieties.

Salinity decline promotes growth and harmful blooms of a toxic alga by diverting carbon flow.

Global climate change intensifies the water cycle and makes freshest waters become fresher and vice-versa. But how this change impacts phytoplankton in coastal, particularly harmful algal blooms (HABs), remains poorly understood. Here, we monitored a coastal bay for a decade and found a significant correlation between salinity decline and the increase of Karenia mikimotoi blooms. To examine the physiological linkage between salinity decreases and K. mikimotoi blooms, we compare chemical, physiological and multi-omic profiles of this species in laboratory cultures under high (33) and low (25) salinities. Under low salinity, photosynthetic efficiency and capacity as well as growth rate and cellular protein content were significantly higher than that under high salinity. More strikingly, the omics data show that low salinity activated the glyoxylate shunt to bypass the decarboxylation reaction in the tricarboxylic acid cycle, hence redirecting carbon from CO2 release to biosynthesis. Furthermore, the enhanced glyoxylate cycle could promote hydrogen peroxide metabolism, consistent with the detected decrease in reactive oxygen species. These findings suggest that salinity declines can reprogram metabolism to enhance cell proliferation, thus promoting bloom formation in HAB species like K. mikimotoi, which has important ecological implications for future climate-driven salinity declines in the coastal ocean with respect to HAB outbreaks.

Investigating the Effect of Water Softening on Polymer Adsorption onto Carbonates through Single-Phase and Two-Phase Experiments

Summary Polymer retention is considered a major challenge in polymer flooding applications, especially in carbonates. This is due to the prevailing conditions of low permeability (&amp;lt;100 md), high temperature (&amp;gt;85°C), and high salinity (&amp;gt;100,000 ppm) generally found in these formations, which limit the effectiveness of commonly used polymers such as hydrolyzed polyacrylamide (HPAM) and xanthan gum. To address these challenges, a polymer based on acrylamide tertiary butyl sulfonate (ATBS) has been used due to its tolerance to high-temperature and -salinity conditions. However, the high cost of manufacturing these polymers, combined with their anionic properties that promote adsorption onto positively charged carbonate rocks, necessitates the exploration of methods to reduce polymer retention. In this study, we aim to determine the sufficient concentration of hardness ions (Ca2+ and Mg2+) required to significantly reduce the adsorption of this polymer. The study is unique in its focus on mitigating polymer retention in carbonate formations using softened brine, as no prior research has investigated this aspect. Four different brines were investigated with a salinity of 8,000 ppm total dissolved salts (TDS) and varying ionic composition designed mainly by eliminating the hardness-causing ions, Ca2+ and Mg2+. A geochemical study was performed using the PHREEQC software to analyze the interaction between these injected brines and the rock. Furthermore, comprehensive rheological and static adsorption studies were performed at a temperature of 25°C using the potential ATBS-based polymer to evaluate the polymer performance and adsorption in these brines. Later, dynamic adsorption studies were conducted in both single-phase and two-phase conditions to further quantify polymer adsorption. The geochemical study showed an anhydrite saturation index (SI) of less than 0.5 for all the brines used when interacting with the rock, indicating a very low tendency for calcium sulfate precipitation. Furthermore, the rheological studies showed that polymer viscosity significantly increased with reduced hardness, where a polymer solution viscosity of 7.5 cp was obtained in zero hardness brine, nearly 1.5 times higher than the polymer viscosity of the base makeup brine of 8,000 ppm. Moreover, it was observed that, by carefully tuning the concentrations of the divalent cations, the polymer concentration consumption for the required target viscosity was reduced by 40–50%. For the single-phase static adsorption experiments, the polymer solution in softened brines resulted in lower adsorption in the range of 37–62 µg/g-rock as opposed to 102 µg/g-rock for the base makeup brine. On the other hand, the single-phase dynamic adsorption results showed an even lowered polymer adsorption of 33 µg/g-rock for the softened brine compared with 45 µg/g-rock for the base makeup brine. Additionally, the single-phase dynamic adsorption studies showed a remarkable improvement in polymer injectivity using softened brine. The polymer retention in wettability-altered cores was further reduced. The study highlights that water softening improves the performance of polymers, specifically in terms of lowering polymer adsorption. It concludes that a threshold hardness level (Ca2+ and Mg2+) of approximately 100 ppm is sufficient to achieve a significant reduction in polymer adsorption for the tested experimental conditions. In this paper, we show that the softened water increases the polymer viscosity and reduces polymer adsorption, which leads to an overall reduction in polymer consumption. Hence, the softened makeup water has the potential to enhance the application envelope of this potential polymer for polymer flood, especially in the case of carbonate reservoirs.

Genetic mechanism and main controlling factors of high-quality clastic rock reservoirs in deep and ultradeep layers: A case study of Oligocene Linhe Formation in Linhe Depression, Hetao Basin, NW China

Based on new data from cores, drilling and logging, combined with extensive rock and mineral testing analysis, a systematic analysis is conducted on the characteristics, diagenesis types, genesis and controlling factors of deep to ultra-deep abnormally high porosity clastic rock reservoirs in the Oligocene Linhe Formation in the Hetao Basin. The reservoir space of the deep to ultra-deep clastic rock reservoirs in the Linhe Formation is mainly primary pores, and the coupling of three favorable diagenetic elements, namely the rock fabric with strong compaction resistance, weak thermal compaction diagenetic dynamic field, and diagenetic environment with weak fluid compaction-weak cementation, is conducive to the preservation of primary pores. The Linhe Formation clastic rocks have a superior preexisting material composition, with an average total content of 90% for quartz, feldspar, and rigid rock fragments, and strong resistance to compaction. The geothermal gradient in Linhe Depression in the range of (2.0–2.6) °C/100 m is low, and together with the burial history of long-term shallow burial and late rapid deep burial, it forms a weak thermal compaction diagenetic dynamic field environment. The diagenetic environment of the saline lake basin is characterized by weak fluid compaction. At the same time, the paleosalinity has zoning characteristics, and weak cementation in low salinity areas is conducive to the preservation of primary pores. The hydrodynamic conditions of sedimentation, salinity differentiation of ancient water in saline lake basins, and sand body thickness jointly control the distribution of high-quality reservoirs in the Linhe Formation.