Salinity Research Articles

Modification and mechanistic study of fluid/fluid and carbonate rock/fluid interfaces using a glycolipid biosurfactant from an indigenous strain of Gordonia terrae for MEOR applications

To clarify the mechanism of the interface behavior between carbonate surface/biosurfactant solution/oil systems, the interfacial tension (IFT), surface wettability, spreading coefficient (SC), and capillary number were investigated with regard to the synergistic effects of a biosurfactant from an indigenous Gordonia terrae strain (isolated from an Iranian oil reservoir), formation water salinity, and pH using response surface methodology (RSM-CCD). According to the analysis of variance results, the process effectively depicted by the quadratic model demonstrated statistical significance in terms of the responses of IFT, wettability alteration, and SC, which were significantly affected by biosurfactant concentration. The optimal conditions were 0.260 g/L biosurfactant, 36.202 g/L salinity, and a pH of 5.9. Accordingly, the quadratic model was verified using the estimated optimal parameters, thereby confirming the accuracy of the model in which a strongly water-wet surface (contact angle change from 159° to 31°) and IFT reduction (from 23.96 to 1.26 mN/m) resulted in an SC of near-zero value (−0.18) and 25 % recovery of oil during the imbibition experiments after secondary water flooding. The desorption of the polar components of crude oil from the dolomite rock surface was also investigated through determining the un-coverage ratios of the elements using energy dispersive X-ray microanalysis and characterization. Although the solutions containing biosurfactants contributed to the alteration of the rock surface wettability, their performance strongly depended on the pH and salinity, resulting in different desorption ratios. The desorption of approximately 40 % of the adsorbed organic compounds from the carbonate surface was a critical limiting factor affecting the surface properties of the rock, and was responsible for altering the wettability to water-wet conditions. The results of this study are expected to contribute to the development of effective biosurfactant-flooding techniques for MEOR.

Analysis of the water quality of the Wiringtasi River, Barru Regency, Indonesia, in relation to fish cultivation

Objective: This research aims to determine the quality of water along the Wiringtasi River, Barru Regency, Indonesia in relation to the development of fish cultivation. Material and method: Sampling was carried out by random sampling by selecting three research locations, namely location 1 is a river location close to rice fields, location 2 is a location close to pond areas and beaches, and location 3 is a location around the mouth of the Wiringtasi River. The data collected is water quality parameter data, which includes temperature, dissolved oxygen, pH, and salinity. The data obtained is then processed and linked to fish cultivation needs. The data was then analyzed using descriptive analysis. Results: The research results show that the water temperature in the Wiringtasi river is in the average range of 29.4–30.4 oC. The average dissolved oxygen at the research location is in the range of 4.31–5.08 ppm. The average value of water pH at the research location is in the range of 6.33-7.17, while the average value of water salinity at the research location is in the range of 12.67-36.83 ppt. Conclusion: All water quality parameters measured in the Wiringtasi River, Barru Regency, Indonesia, are still in accordance with the growth and survival needs of fish.

Isolation, Identification, and Application of Endophytic Fungi from Lavandula stoechas L.: Mitigating Salinity Stress in Hydroponic Winter Cereal Fodder

Soil and irrigation water salinity is a growing global problem affecting farmland, due to poor agricultural practices and climate change, leading to reduced crop yields. Given the limited amount of arable land and the need to boost production, hydroponic systems offer a viable solution. Additionally, endophytic fungi have been shown to mitigate salinity effects through symbiosis with plants. This study evaluated three endophytic fungi isolated from Lavandula stoechas L. in the grasslands of Extremadura (i.e., Diplodia corticola L11, Leptobacillium leptobactrum L15, and Cladosporium cladosporioides L16) for their ability to improve hydroponic forage production under saline conditions. In vitro experiments were conducted assessing plant growth promotion and fungal growth under salinity, followed by research evaluating the impact of fungal inoculation on hydroponic wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) forages irrigated with NaCl solutions (0, 100, and 200 mM). The results showed improved fungal growth and production of plant growth-promoting substances, which could explain the improved plant germination, shoot and root length, fresh and dry weight, and yield of inoculated plants growing under salinity. Plants inoculated with L15 or L16 showed the best performance overall. L15 demonstrated broader bioactivity in vitro, potentially explaining its superior performance in both wheat and barley growth. Conversely, L16 was more effective in barley, while L11 was beneficial in wheat but detrimental in barley. This study provides a preliminary exploration of the capabilities of these fungi and their optimization for hydroponic forage production.

Methane in the Water Column of the Gdansk Deep (Baltic Sea): Seasonal and Vertical Variability

The study of the vertical distribution of methane dissolved in water and related parameters (water temperature and salinity, dissolved oxygen concentration) was carried out in 2021–2023 at the offshore carbon supersite Rosyanka in the Gdansk Deep of the Baltic Sea. Measurements with such frequency (a total of 16 surveys) were carried out in the region for the first time. Methane concentrations varied over a fairly wide range (0.000–1.122 μmol/L), and increased with depth, which is a typical distribution for the Baltic Sea and is associated with the vertical stratification of the water column. Single maximum values were characteristic of the layer extending from the bottom to the upper boundary of the halocline, which indicates the flow of methane from bottom sediments into the water column. In the near-surface layer (5–15 m), a weakly pronounced peak in methane concentrations was observed, which is a manifestation of the “oceanic methane paradox”. No pronounced seasonality was detected in the vertical distribution of dissolved methane; the correlation between temperature, salinity, oxygen, and methane content turned out to be low.

Irrigation Water Salinity Affects Solute Transport and Its Potential Factors Influencing Salt Distribution in Unsaturated Homogenous Red Soil

As a promising alternative water source to alleviate irrigation water scarcity in red soil regions in southern China, low-quality water could enhance regional water resource utilization and promote sustainable agriculture. However, its soluble salt and ions could affect soil solute distribution and transport, potentially hindering crop growth. Undoubtedly, it is necessary to understand the mechanism of solute transport in red soil under low-quality water irrigation with different water salinity levels. Therefore, a one-dimensional vertical water infiltration experiment and a solute breakthrough experiment were conducted to evaluate the solute transport (soluble salt, Na+, and Cl−) in unsaturated and saturated homogenous red soil at different salinity levels [1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g/L] when irrigated with simulated low-quality water using analytical-grade NaCl. Moreover, the potential factors affecting salt distribution in unsaturated red soil were determined. The findings indicate positive linear relationships between accumulations of three solutes and irrigation water salinity. Generally, the depth of maximum solute concentration increased with the increase in irrigation water salinity. Soluble salt, Na+, and Cl− exhibited early breakthrough and trailing in red soil, but higher irrigation water salinity could reduce PV and retardation. A mobile and immobile water model (MIM) showed that convection was dominant in solute transport in red soil under low-quality water irrigation. D decreased as a power function with increasing irrigation water salinity, while v and R decreased linearly. Furthermore, the red soil can adsorb Cl− resulting from its special charge characteristics under low-quality water irrigation, which may be the main source of salt adsorption. Additionally, v > soil pH > βsalt primarily influenced salt distribution in the 0–40 cm soil profile. This study can provide insights into solute transport in red soil under low-quality water irrigation, facilitating soil fertility and structure, as well as low-quality water irrigation strategy optimization.

Effect of Different Salinities on the Biochemical Properties and Meat Quality of Adult Freshwater Drum (Aplodinotus grunniens) During Temporary Rearing.

Salinity is a significant environmental component that affects the physiological state of aquatic species. This study aimed to investigate whether water salinity had an impact on the biochemical properties and meat quality of adult Aplodinotus grunniens during temporary rearing of 7 days. Salinity caused increased osmotic pressure and antioxidant enzyme activities of Aplodinotus grunniens, which were attributed to the increase in the content of alanine and glutamate. It raised the hardness and shear force with an increase in salinity, leading to an increase in water-holding capacity. Salinity enhanced the DHA ratio with a decrease in the atherosclerotic index and thrombosis index. Combined with the increase in flavor amino acids and nucleotides, salinity enhanced the umami taste of Aplodinotus grunniens. These findings suggest that temporary rearing in salinity might be a practical approach to improving the meat quality of adult Aplodinotus grunniens.

The East Asian species <i>Thermocyclops taihokuensis</i> (Harada 1931) (Crustacea, Copepoda, Cyclopoida) in the Taganrog Bay of Azov Sea

In August–September 2021–2023, the composition and abundance of pelagic Copepoda in the Don River delta and in the eastern part of the Taganrog Bay of Azov Sea were studied. The East Asian copepod, Thermocyclops taihokuensis (Harada 1931) was recorded for the first time from the eastern part of the bay at a water salinity of 3.5–5.8‰. The species must have entered the Taganrog Bay with water from the Don River. The largest population of the invader was registered in the Don River delta in August 2021 ( 7.000 ind./m3); in the bay in September 2023 it reached 4.000 ind./m3. The body size and fertility of the invader were close to those in the Tsimlyansk Reservoir and the Don River. In 2023, the reproduction of T. taihokuensis was noted in the bay with an extremely low (about 1%) proportion of mature individuals in the population. The species seems to have not yet been fully naturalized in the bay, its population still being supported by bioflow from the Don River delta. The potential consequences of the introduction of this alien copepod for the zooplankton of Taganrog Bay are discussed.

Antarctic ice-shelf meltwater outflows in satellite radar imagery: ground-truthing and basal channel observations

Abstract Ice shelves regulate the flow of the Antarctic ice sheet toward the ocean and its contribution to sea-level rise. Accurately monitoring the basal and surface melting of ice shelves is therefore essential for predicting the ice sheet's response to climatic warming. In this study, we utilize Sentinel-1A synthetic aperture radar satellite imagery combined with shipboard measurements of water temperature and salinity to investigate the presence of surficial meltwater plumes along the Antarctic coastline. Our approach reveals a strong correlation between areas of pronounced low radar backscatter extending from ice shelves and significant decreases in water temperature and salinity, suggesting meltwater-enriched ocean waters. We propose that the low radar backscatter signature of meltwater outflows is caused by stable stratification of the upper water column, driven by density contrasts from buoyant, low-salinity meltwater and surface current shear that reduce Bragg scattering waves. The resulting smooth water surfaces were observed adjacent to the surface expression of deep basal channels, documented in a helicopter survey along part of the Bellingshausen Sea ice edge. We present high-temporal resolution satellite radar as a tool for identifying meltwater release from beneath ice shelves, capable of all-weather, day-and-night imaging.

Study of the varietal behavior of 07 durum wheat varieties (Triticum durum Desf.) in the Oued Righ Valley (ITDAS Station)

Cereal production in the Oued Righ Valley is limited by several factors, including high temperatures and the salinity of irrigation water. These constraints cause significant variations in crop behavior and yield. This study aims to evaluate the performance of seven durum wheat varieties at the El Arfiane demonstration and seed production farm (ITDAS) in the Oued Righ Valley in the south East of Algeria. The evaluation focuses on morphological parameters and yield components To identify the variety or varieties that demonstrate favorable performance and yield, thus encouraging local farmers to cultivate them. The results of this study indicate significant differences in morphological parameters such as plant height, spike length, number of spikes per square meter, and number of grains per spike. However, other measured parameters, such as the number of tillers per plant, thousand-grain weight TGW, grain yield, and harvest index, The methodology employed in this study follows a completely randomized block design with three replications. The experimental design includes a set of experimental units arranged in blocks, with treatments randomly assigned within each block, hence the term "completely randomized block." Each treatment appears only once in each block. The blocks are typically placed contiguously to facilitate observations and task execution. This design is widely used in agronomy as it simplifies task execution and the comparison of treatments. Despite an acceptable thousand-grain weight this year, ranging from 37.06g for variety T4 to 27.6g for variety T1, the yields were low. The highest biological yield was 33.11 quintals per hectare for variety T5, while the lowest yield was 11.39 (T2) quintals per hectare. Several factors, including pigeon attacks and harvest losses, contributed to the reduced real yield.

Preliminary experimental study of low salinity effect on organic polar compounds desorption in Hassi Messaoud field-Algeria

Low salinity water (LSW) injection is a well-recognized enhanced oil recovery method that has proved to increase oil recovery. Despite its simple implementation and low cost, no experimental investigations have been reporting its application in Algeria’s oil fields. The present work investigates the impact of LSW injection and identifies the role of organic polar compounds on oil trapping in Hassi Messaoud oil field. The study involves adsorption/desorption experiments using acid/amine organic polar compounds dissolved in non-polar refined oil while employing rock drilling cuttings. Subsequent validation of desorption data is performed by employing crude oil in both Amott tests and micro-model displacement tests using various water salinity ranges. It was evident that at water salinities ranging from 1000 to 2000 ppm, the interfacial tension decreased to 10−2 mN/m, leading to favorable rock wetting behavior and increased oil recovery of 9.18% and 20.07% for amine and acid compounds, respectively. The wettability alteration mechanism was proposed as the main contributor since the actual interfacial tension of natural surfactant might not significantly impact oil recovery. The implementation of LSW injection in Algerian fields presents fresh prospects for future enhanced oil recovery projects.

Change in Activities of Enzymes of Energy and Carbohydrate Metabolism in Pink Salmon Oncorhynchus gorbuscha (Walb.) Smolts with Change in Environmental Salinity.

Activities of key enzymes of energy and carbohydrate metabolism (cytochrome c oxidase (COX), lactate dehydrogenase (LDH), aldolase, glucose 6-phosphate dehydrogenase (G6PDH), and 1-glycerophosphate dehydrogenase (1-GPDH)) were studied in pink salmon Oncorhynchus gorbuscha (Walb.) smolts from the White Sea in a cage experiment simulating the transition from a freshwater to a marine environment. A decrease in COX, G6PDH, and 1-GPDH activities and an increase in LDH and aldolase activities were observed in juveniles with an increase in water salinity. Based on the findings, a redistribution of energy substrates between the reactions of aerobic and anaerobic metabolism towards higher anaerobic ATP synthesis was assumed for pink salmon. This may indicate that adaptive mechanisms rearrange metabolism to provide energy for osmoregulation in pink salmon juveniles when the salinity changes in their habitat.

DEVELOPMENT OF WATER QUALITY MONITORING SYSTEM IN SHRIMP PONDS BASED ON INTERNET OF THINGS (IOT)

This type of research is research and development (R&D) which uses the waterfall development model. The aim of this research is to produce a water quality monitoring system in shrimp ponds based on the Internet of Things (IoT) and to find out the results of testing the development of the system using the ISO 25010 standard. This development involves the application of ESP32, Relay, Toa Siren, DS18b20 Temperature Sensor, pH Sensor Module 4502C, Water Salinity and Turbidity Sensor which allows users to get real-time pond water quality monitoring information via the Telegram application. The test results for the reliability aspect have met the fault tolerance sub-characteristic standards because the percentage of measurement error obtained for the temperature sensor was 0.10%, pH 0.54%, salinity 1.19%, and turbidity 1.00%, still within the permitted tolerance limits. Functionality suitability testing shows that this tool obtains a percentage of 100%, indicating that the system is suitable for use. This tool also meets the portability aspect because it can be used on various devices with different operating systems. Apart from that, the usability evaluation results from user responses are in the very good category with an average of >4.2.

Current state and open issues of priming onion seeds

Relevance. In the context of climate change, onion cultivation has become a challenge and innovative solutions are needed to support breeders and seed producers as well as farmers, starting with critical issues of seed quality. Seed priming successfully improves seed viability, which leads to rapid and uniform germination and emergence of onion seedlings.Results. Priming onion seeds can improve viability, especially under unfavorable conditions such as low/high temperatures, reduced water availability and salinity. It is a simple, low-cost and low-risk intervention that can be a useful technology for farmers and have a positive impact on their livelihoods by increasing the rate of seed germination, increasing the rate of plant development, reducing harvest time and increasing yields. Although this method is common for radish, tomato, carrot and cabbage seeds, this method is less popular for onions. This review provides an up-to-date picture of the scientific and technological advances that have contributed to increasing seed germination and vigor in onion plants to date. For large-scale commercial use, optimal priming methods and conditions tailored to different varieties or seed lots will require further extensive experimental work. It cannot be denied that seed priming technology is characterized by ease of operation, low cost and high practical value in industrial and market contexts. It can be foreseen that this technology will have wider prospects in agricultural production and green building. In addition, seed priming can effectively restore or enhance seed viability and ensure successful retention of germplasm resources and subsequent development, especially for onion seeds that rapidly lose viability.

Slightly Saline Water Improved Physiology, Growth, and Yield of Tomato Plants in Yellow Sand Substrate

Efficient utilization of saline water and yellow sand resources can enhance water and soil resource management while boosting crop yields in Xinjiang. This study conducted a two-season field experiment in Alar City, Xinjiang, from March to July 2023 and August 2023 to January 2024. The objective was to examine the effects of different irrigation water salinities (2, 3, 4, 5, and 6 g·L−1) on the physiology, growth, and yield of sand-cultured tomatoes grown in yellow sand slag. Groundwater irrigation with salinity levels of 0.8–1 g·L−1 was used as the control (CK). The results showed that the salinity of the substrate gradually increased with the salinity of irrigation water in each treatment. The salt accumulation increased by 59.5%, 82.5%, and 99.5% at the end of the experiment for T3 (4 g·L−1), T4 (5 g·L−1), and T5 (6 g·L−1), respectively, compared to CK. As the salinity of irrigation water increased, plant height, stem thickness, chlorophyll content, net photosynthesis rate, stomatal conductance, transpiration rate, and total yield of tomato showed an increasing and then decreasing trend, in which the total tomato yield of the T2 (3 g·L−1) treatment was significantly increased by 35.2% compared with that of CK between the two seasons. In contrast, as the salinity of irrigation water increased, the inter-cellular CO2 concentration of tomato leaves showed a decreasing and then increasing trend, with the T2 treatment having the lowest inter-cellular CO2 concentration. Pathway analysis revealed that appropriate salinity levels increased tomato yield by regulating inter-cellular CO2 concentration. Based on these findings, a 3 g·L−1 salinity level is recommended for irrigating sand-cultured tomatoes to maximize yellow sand resource use, address freshwater shortages, and optimize water and soil management in the Xinjiang region.

Germination of chief fire seeds cockscomb cultivar under saline stress conditions induced by sodium chloride

Cockscomb plant, Chief fire cultivar, is used as an ornamental, medicinal and non-conventional food plant (NCFP) and is cultivated from the north to the center-west of Brazil; however, these areas suffer from adverse environmental factors such as salinity stress. The objective of this study was to evaluate the seed germination performance and vigor of Celosia cristata L. var. Chief Fire seedlings exposed to salinity during the germination phase. To carry out the work, C. cristata seeds were sown in gerboxes conditioned to increasing doses of sodium chloride (NaCl), obtained by dissolving the salt in distilled water, obtaining electrical conductivities of 2.0; 4.0; 6.0 and 8.0 dS.m-1, constituting the treatments. An additional group was treated only with distilled water and was used as a control for the experiment. The experiment was conducted in a completely randomized design, with a total of five treatments and four replicates of 25 seeds. The parameters assessed were: first germination count, germination, germination speed index (GVI), mean germination time (MGT), length of aerial part and primary root. The data was submitted to analysis of variance and the means were compared using the Scott-Knott test at 5% significance. Based on the results obtained, it can be concluded that the conditions of salt stress induced by NaCl were not harmful to the germination of C. cristata, presenting itself as a species tolerant to water salinity during seed germination, since the variables analyzed showed no signs of deleterious effects as the salt concentration was increased.

Salinity challenges and adaptive strategies in salinization-affected coastal Bangladesh: Implications for agricultural sustainability and water resource management

Abstract Salinization has become a rising global concern due to its notable effects on agriculture and freshwater resources. Coastal region of Bangladesh has been struggling with elevated levels of soil and water salinity, exacerbated by storm surges and rising sea levels. We assessed nutrient and salinity contents in agricultural and homestead lands, and the level of salinity in pond and canal water in six sub-districts in coastal Bangladesh. Finally, using household (HH) survey, focus group discussion (FGD) and key informant interview (KII), we explored the adaptive practices and challenges of salinity issues in agriculture and drinking water management. Soil nitrogen, phosphorus, and potassium contents exhibited significant variations across the sub-districts, which reflect the diversity of agricultural practices and soil management strategies. However, there was no notable difference in soil salinity across the sub-districts, which underscores the commonality of soil salinity as a pressing concern. Shyamnagar (13.99 dS m−1) recorded the highest level of pond water salinity, followed by Assasuni (13.96 dS m−1), Dacope (13.91 dS m−1), Koyra (13.58 dS m−1), Morrelganj (13.33 dS m−1), and Mongla (13.19 dS m−1) sub-districts, which highlights that water salinity decreased from exposed coast to the landward areas. Respondents in HH surveys, FGDs and KIIs identified salinity as a major challenge in agriculture and drinking water. Furthermore, climate-related stresses were recognized as significant challenges impacting crop productivity. The research highlights the feasibility of rainwater harvesting, with 89%–100% of HHs harvest rainwater in HH tanks, as an effective adaptive practice for managing drinking water. The study emphasizes the positive impact of vermicompost in reducing soil salinity levels, which is demonstrated by the 43%–88% of HHs using this practice, indicating its potential as a nature-based solution to address soil salinization. The findings underscore the need for resilient agricultural systems and sustainable water management approaches to tackle these challenges.

Residual Effect of Microbial-Inoculated Biochar with Nitrogen on Rice Growth and Salinity Reduction in Paddy Soil.

Increasing soil and water salinity threatens global agriculture, particularly affecting rice. This study investigated the residual effects of microbial biochar and nitrogen fertilizer in mitigating salt stress in paddy soil and regulating the biochemical characteristics of rice plants. Two rice varieties, Shuang Liang You 138 (SLY138), a salt-tolerant, and Jing Liang You 534 (JLY534), a salt-sensitive, were grown under 0.4 ds/m EC (S0) and 6.84 ds/m EC (S1) in a glass house under controlled conditions. Three types of biochar-rice straw biochar (BC), fungal biochar (BF), and bacterial biochar (BB)-were applied alongside two nitrogen (N) fertilizer rates (60 kg ha-1 and 120 kg ha-1) in a previous study. The required salinity levels were maintained in respective pots through the application of saline irrigation water. Results showed that residual effects of microbial biochars (BF and BB) had higher salt mitigation efficiency than sole BC. The combination of BB and N fertilizer (BB + N120) significantly decreased soil pH by 23.45% and Na+ levels by 46.85%, creating a more conducive environment for rice growth by enhancing beneficial microbial abundance and decreasing pathogenic fungi in saline soil. Microbial biochars (BF and BB) positively improved soil properties (physicochemical) and biochemical and physiological properties of plants, ultimately rice growth. SLY138 significantly had a less severe response to salt stress compared to JLY534. The mitigation effects of BB + N120 kg ha-1 were particularly favorable for SLY138. In summary, the combined residual effect of BF and BB with N120 kg ha-1, especially bacterial biochar (BB), played a positive role in alleviating salt stress on rice growth, suggesting its potential utility for enhancing rice yield in paddy fields.

Biodiversity of microorganisms in the Baltic Sea: the power of novel methods in the identification of marine microbes.

Until recently, the data on the diversity of the entire microbial community from the Baltic Sea were relatively rare and very scarce. However, modern molecular methods have provided new insights into this field with interesting results. They can be summarized as follows. (i) Although low salinity causes a reduction in the biodiversity of multicellular species relative to the populations of the North-East Atlantic, no such reduction occurs in bacterial diversity. (ii) Among cyanobacteria, the picocyanobacterial group dominates when considering gene abundance, while filamentous cyanobacteria dominate in means of biomass. (iii) The diversity of diatoms and dinoflagellates is significantly larger than described a few decades ago; however, molecular studies on these groups are still scarce. (iv) Knowledge gaps in other protistan communities are evident. (v) Salinity is the main limiting parameter of pelagic fungal community composition, while the benthic fungal diversity is shaped by water depth, salinity, and sediment C and N availability. (vi) Bacteriophages are the predominant group of viruses, while among viruses infecting eukaryotic hosts, Phycodnaviridae are the most abundant; the Baltic Sea virome is contaminated with viruses originating from urban and/or industrial habitats. These features make the Baltic Sea microbiome specific and unique among other marine environments.

Biogeographic shifts in the microbial co-occurrence network features of three domains across complex environmental gradients in subtropical coastal waters

BackgroundBacteria, Archaea, and Microeukaryotes comprise taxonomic domains that interact in mediating biogeochemical cycles in coastal waters. Many studies have revealed contrasting biogeographic patterns of community structure and assembly mechanisms in microbial communities from different domains in coastal ecosystems; however, knowledge of specific biogeographic patterns on microbial co-occurrence relationships across complex coastal environmental gradients remains limited. Using a dense sampling scheme at the regional scale, SSU rRNA gene amplicon sequencing, and network analysis, we investigated intra- and inter-domain co-occurrence relationships and network topology-based biogeographic patterns from three microbial domains in coastal waters that show environmental gradients across the inshore-nearshore-offshore continuum in the East China Sea.ResultsOverall, we found the highest complexity and connectivity in the bacterial network, the highest modularity in the archaeal network, and the lowest complexity, connectivity, and modularity in the microeukaryotic network. Although microbial co-occurrence networks from the three domains showed distinct topological features, they exhibited a consistent biogeographic pattern across the inshore-nearshore-offshore continuum. Specifically, the nearshore zones with intermediate levels of terrestrial impacts reflected by multiple environmental factors (including water temperature, salinity, pH, dissolved oxygen, and nutrient-related parameters) had a higher intensity of microbial co-occurrence for all three domains. In contrast, the intensity of microbial co-occurrence was weaker in both the inshore and the offshore zones at the two ends of the environmental gradients. Archaea occupied a central position in the microbial inter-domain co-occurrence network. In particular, members of the Thaumarchaeota Marine Group I (MGI, now placed within the Family Nitrosopumilaceae of the Phylum Thermoproteota) appeared to be the hubs in the biogeographic shift between inter-domain network modules across environmental gradients.ConclusionsOur work offers new insights into microbial biogeography by integrating network features into biogeographic patterns, towards a better understanding of the potential of microbial interactions in shaping biogeographic patterns of coastal marine microbiota.

Techno-economic investigation of an entirely solar-powered hybrid HDH/RO desalination plant for moderate water demand under various operating conditions

The study presented a scalable, entirely solar-powered hybrid desalination system suitable for moderate demand and valid for various water salinities. The system merged two desalination techniques: HDH (humidification-dehumidification) and RO (reverse osmosis) units. The required power for all components was obtained from a photovoltaic system. The experiments were conducted to evaluate the separate units and hybrid system performances under different conditions, including various sprayed hot water (to the HDH) temperatures, RO feed water temperatures, air velocities, and water salinities. Based on the recorded data, the techno-economic analyses were conducted to assess the gain output ratio (GOR), recovery ratio (RR), specific energy consumption (SEC), the total amount of dissolved solids (TDS), and product cost. As a result, the RO unit's productivity increased almost linearly with feed temperature, showing a maximum hourly yield of 60 L/m2. In contrast, HDH productivity showed exponential growth with feed temperature, achieving a maximum hourly yield of 18 L/m2. The SEC of the RO unit decreased from 1.1 kWh/m³ to 0.63 kWh/m³ when using the rejected HDH's hot brine. The hybrid system's accumulated productivity reached 535 L/m2, significantly higher than the standalone HDH (58.5 L/m2) and standalone RO (368 L/m2). Additionally, the hybrid system demonstrated substantial improvements in GOR and RR, with daily values of 11.15 and 55.73%, respectively. Economically, the distillate water cost was significantly lower, at 0.63 $/m³ for the HDH/RO system compared to 3.51 $/m³ for the standalone HDH.