Low Salinity Levels Research Articles

Baseline Study on Microplastic Distribution in the Open Surface Waters of the Korean Southwest Sea

This study investigated microplastic distribution characteristics by collecting surface seawater from sea areas to the south of Jeju Island in August 2020. The average microplastic abundance was 0.46 ± 0.27 particles/L (n = 23), and PE had a high ratio, averaging 53%. The levels of fragments and fibers were observed to be 69% and 31% on average, respectively. The most common size of the microplastics was on average 0.02–0.30 mm at a level of 69%. We found a higher abundance of microplastics in the study area than in other open waters such as the Arctic Central Basin and the Atlantic Ocean, whereas the abundance was lower than that in previous studies on coastal areas. We studied an area of open sea connecting China, Japan, and the Pacific Ocean, and, in this region, the microplastic distribution varies depending on sea currents in the surrounding areas. In the summer, the western and central regions of the study sea area have low salinity levels due to discharge from China’s Yangtze River. This generally indicates that high-density plastic deposits are found in the Yangtze River estuary, and low-density plastics are found in the study area. Furthermore, this implies that low- and high-density plastics are transported in water for long periods of time due to the Taiwan Warm Current and because the eastern sea area has high salinity.

Dynamics of sewage outfall plumes based on Landsat-8-derived sea surface salinity and tidal characteristics.

In the face of growing marine pollution, assessment of the sewage outfall discharges is essential as it affects the seawater quality. The study demonstrates sea surface salinity (SSS) variations caused by sewage discharges and links it with tidal characteristics to hypothesize the dynamics of sewage outfall plumes. SSS is estimated using a multilinear regression model based on Landsat-8 (L8) OLI reflectance and in situ SSS data of 2013-2014. Using the validated model, the SSS of the 2018 image is predicted and evidenced by its relationship with colored dissolved organic matter (CDOM). The preliminary results of the hypothesis are encouraging and found that the dispersion patterns of outfall plumes exhibit distinct characteristics depending on the intra-tidal range and hour. The findings indicate a lower SSS in the outfall plume zone than in ambient seawater due to dilution caused by partially treated sewage discharges from diffusers. The plumes observed during the macro tidal range are long and narrowly spread alongshore. In contrast, during the meso and microtidal ranges, the plumes are shorter and are primarily dispersed offshore rather than alongshore. During slack times, low salinity levels are visibly concentrated around outfalls as there is no water movement to disperse the accumulated sewage discharges from diffusers. These observations suggest that slack periods and low-tidal conditions could be significant factors contributing to the accumulation of pollutants in coastal waters. The study further suggests more datasets such as wind speed, wind direction, and density variations are needed to understand the processes influencing the outfall plume dynamics and variation in SSS. The study recommends increasing the treatment capabilities of existing treatment facilities from primary to tertiary treatment levels. Furthermore, it is important to warn and educate the public about the health risks associated with exposure to partially treated sewage that is discharged from outfalls.

Spatio-temporal variation of water salinity in mangroves revealed by continuous monitoring and its relationship to floristic diversity

Salinity is among the most critical factors limiting the growth and species distribution of coastal plants. Water salinity in estuarine ecosystems varies temporally and spatially, but the variation patterns across different time scales and salinity fluctuation have rarely been quantified. The effects of salinity on floristic diversity in mangroves are not fully understood due to the temporal and spatial heterogeneity of salinity. In this study, we monitored water salinity at an interval of 10-min over one year in three mangrove catchment areas representing the outer part, middle part, and inner part respectively of Dongzhai Bay, Hainan, China. The number of mangrove community types and dominant mangrove species of the three catchment areas were also investigated. We found that the diurnal variation and dry-season intra-month variation in water salinity were driven by tidal cycles. The seasonal variation in water salinity was mainly driven by rainfall with higher salinity occurring in the dry season and lower salinity occurring in the wet season. Spatially, water salinity was highest at the outer part, intermediate at the middle part, and lowest at the inner part of the bay. The intra-month and annual fluctuations of water salinity were highest at the middle part and lowest at the outer part of the bay. The number of mangrove community types and dominant species were lowest at the outer part, intermediate at the middle part, and highest at the inner part of the bay. These results suggest that the temporal variation of water salinity in mangroves is driven by different factors at different time scales and therefore it is necessary to measure water salinity at different time scales to get a complete picture of the saline environment that mangroves experience. Spatially, lower salinity levels benefit mangrove species richness within a bay landscape, however, further research is needed to distinguish the effects of salinity fluctuation and salinity level in affecting mangrove species richness.

Impacts of different salinity levels on seedling growth and survival of black mangrove (Avicennia germinans)

Abstract. Matto AA, Jaikishun S, Ram M. 2023. Impacts of different salinity levels on seedling growth and survival of black mangrove (Avicennia germinans). Asian J For 7: 67-73. Mangroves are important for coastal protection and provide numerous ecosystem services such as breeding, feeding, and nursery grounds for commercial fishes. This research examined the survivability of black mangrove (Avicennia germinans (L.) L.) seedlings in seven salinity concentrations. Growth parameters were collected every ten days, and a post-harvest analysis was done at the end of the data collection period. The results indicated that as the salinity level increased, the growth of the seedlings was reduced. Salinity can affect the different parameters collected in the growth of young seedlings. In the control, which was given zero salinity (0 ppt), it was noted that the growth parameters were not significantly affected. The lower treatments, such as T2 (15 ppt), 3 (30 ppt), and 4 (45 ppt), indicated that the seedlings strive better in these conditions. In treatment 7, which was the highest salinity level (90 ppt), the growth parameters of the seedlings were reduced. The findings of this research indicated that black mangrove seedlings need a low salinity level to have a good growth establishment. Given the adaptability of A. germinans, these mangrove species are anticipated to be flexible to cope with a wide range of future climatic circumstances.

Effects of salt source and irrigation water salinity on growth, yield and quality parameters of black cumin

AbstractExcess salinity, osmotic stress, toxic ions and ion imbalance negatively affect plant growth. Many crops are classified as salt sensitive. However, there is no information in the literature about the effects of different salt sources (SS) and salinity levels (SLs) on black cumin (Nigella sativa L.). This study was conducted to determine the effects of SL (0.6, 1.5, 2.5 and 5.0 dS/m) prepared separately by different SSs (CaCl2, MgCl2, NaCl, Ca(NO3)2, MgSO4 and Na2SO4) on the evapotranspiration, growth, yield and quality parameters of black cumin. The results showed that the evapotranspiration, soil salinity, plant height, vegetative dry weight and oil content of black cumin were affected only by SL. Both SS and SL have a significant effect on the number of capsules and seed weight. The SS × SL interaction was meaningful on drainage water salinity and the number of seeds. The seed weights under CaCl2, MgCl2, Ca(NO3)2, MgSO4 and Na2SO4 SS were adversely affected even at very low SL. However, the low slope values for these salts reveal that the increase in SL has a limited effect on seed weight. Therefore, it can be recommended to consider both the salt type and SL of irrigation water in black cumin cultivation.

Application of BiVO4/TiO2/CNT Composite Photocatalysts for Membrane Fouling Control and Photocatalytic Membrane Regeneration during Dairy Wastewater Treatment

This study aimed to investigate the performance of composite photocatalytic membranes fabricated by incorporating multiple nanoparticles (TiO2, carbon nanotubes, BiVO4) into polyvinylidene fluoride membrane material for real dairy wastewater treatment. The composite photocatalytic membranes exhibited superior antifouling behavior, lower filtration resistance, better flux, and higher flux recovery ratio than the pristine membrane. Salinity, pH, and lactose concentration are determinant factors that affect filtration resistance and rejection performance during the ultrafiltration of dairy wastewater. Generally, higher irreversible and total resistances and slightly lower chemical oxygen demand (COD) rejections were found at higher salinity (expressed by electric conductivity values of >4 mS/cm) than lower salinity (<4 mS/cm) levels. The presence of lactose in dairy wastewater increased irreversible resistance and severely reduced COD rejection during ultrafiltration due to the ability of lactose to pass through the membranes. It was ascertained that membranes require further treatment after filtrating such wastewater. Lower resistances and slightly better COD rejections were observed at pH 7.5 and pH 9.5 compared to those observed at pH 4. Photocatalytic membranes fouled during the ultrafiltration of real dairy wastewater were regenerated by visible light irradiation. The membrane containing all constituents (i.e., TiO2, carbon nanotubes, and BiVO4) showed the best regeneration performance, exceeding that of the pristine membrane by 30%.

Effect of levels salinity water on seedling growth of Acacia senegal at the Nursery, North Kordofan state, Sudan

This study was conducted in Shikan nursery, Elobied, North Kordofan, from three sources of Acacia senegal seeds (Al-Rahad, Al-Aabasia and Um- Keradem) at January 2022. This study aims to determent the effect of saline water levels on growth of Acacia senegal seedlings. Different salt water levels were used to irrigate seedlings. The response to salt water stress at general level was good with appearance of significant differences at beginning of experiment and these differences disappeared at end of experiment. This indicates that Acacia senegal seedlings were more tolerant of salt water stress to the level of 2898 ms/cm total dissolved salts (T.D.S), can be used for irrigation, especially for Acacia senegal seedlings with a ph between (7.1-8.4). To reduce seedling death, low salinity levels can be relied upon.

Low salinity enhances azo dyes degradation in aerobic granular sludge systems: Performance and mechanism analysis

The biodegradation performance of azo dyes can be enhanced under low salinity conditions, but the internal biodegradation mechanism is still unclear. Aerobic granular sludge (AGS), a salt-tolerant biological wastewater treatment technology, was used in this study to explore the enhancement mechanism of acid orange 7 (AO7) degradation at low salinity level (1.0 %). Results indicated that the AGS structure and reactor performance were almost unaffected by different AO7 concentrations (5–10 mg/L). Compared with salt-free conditions, the AO7 removal efficiency was elevated by 9.9 %–19.0 % at 1.0 % salinity level, owing to the enrichment of AO7 decolorizing bacteria (e.g. Acinetobacter) and functional enzymes (e.g. FMN-dependent azoreductase). The up-regulated genes involving in the key metabolic functions (e.g. carbon metabolism and oxidative phosphorylation) promoted the electron and energy production, thereby facilitating the AO7 decolorization and degradation. These results aid understanding of the enhancement mechanism of AO7 biodegradation under low salinity conditions from macroscopic and microscopic perspectives.

Biological Response of Invasive Parthenium Weed to Elevated Concentration of Atmospheric Carbon Dioxide and Soil Salinity

Climate change elements including elevated atmospheric carbon dioxide (CO2) concentration and soil salinity significantly impact weed biology and management. In this study, we evaluated the performance of a highly invasive plant species, parthenium weed (Parthenium hysterophorus L.) grown at various soil salinity levels (ranging from 0 to 16 dS m−1) at two CO2 concentrations (ambient: 400 ppm and elevated: 700 ppm). The CO2 concentration and soil salinity individually affected various early growth attributes of parthenium weed. The interaction between CO2 and salinity was significant for chlorophyll index, stem dry weight and phenolics content. Parthenium weed plants grew taller (13%), achieved greater leaf area (28%) and produced more dry weight (24%) when raised under elevated as compared with the ambient CO2. Soil salinity had a dose-dependent, negative effect on various growth attributes, chlorophyll index, relative water content and phenolics content. Even the modest levels of salinity (4.2 to 4.6 dS m−1) caused 50% reduction in dry weights of leaves, roots and whole plants. Sodium ion (Na+) concentration peaked at the highest salinity level (16 dS m−1) as compared with the lower salinity levels (0 to 12 dS m−1). Overall, salinity had a negative effect on different growth variables but elevated CO2 improved growth and phenolics content regardless of the salt stress regime. Hence, parthenium weed could benefit from future atmospheric CO2 concentration and may invade some salt-affected areas.

Impacts of co-contaminants and dilution on perchlorate biodegradation using various carbon sources.

This research investigates the biodegradation of perchlorate in the presence of the co-contaminants nitrate and chlorate using soluble and slow-release carbon sources. In addition, the impact of bio-augmentation and dilution, which results in lower total dissolved salts (TDS) and contaminant levels, is examined. Laboratory microcosms were conducted using actual groundwater and soils from a contaminated aquifer. The results revealed that both soluble and slow-release carbon sources support biodegradation of contaminants in the sequence nitrate > chlorate > perchlorate. Degradation rates, including and excluding lag times, revealed that the overall impact of the presence of co-contaminants depends on degradation kinetics and the relative concentrations of the contaminants. When the lag time caused by the presence of the co-contaminants is considered, the degradation rates for chlorate and perchlorate were two to three times slower. The results also show that dilution causes lower initial contaminant concentrations, and consequently, slower degradation rates, which is not desirable. On the other hand, the dilution resulting from the injection of amendments to support remediation promotes desirably lower salinity levels. However, the salinity associated with the presence of sulfate does not inhibit biodegradation. The naturally occurring bacteria were able to support the degradation of all contaminants. Bio-augmentation was effective only in diluted microcosms. Proteobacteria and Firmicutes were the dominant phyla identified in the microcosms.

Morfofisiologia e solutos inorgânicos em melancia irrigada com água salobra em diferentes sistemas de plantio

ABSTRACT Irrigation with brackish water reduces watermelon yield in the Brazilian semiarid region, requiring the establishment of management strategies that reduce the negative impacts caused by salt stress. The objective of this study was to evaluate the morphophysiology and concentration of inorganic solutes in watermelon crops subjected to different electrical conductivities of the irrigation water, using hardened seedlings or direct sowing. The experiment was conducted in the Baixo Acarau Irrigated Perimeter, in the state of Ceara, Brazil. A randomized complete block design was used, with split plots and four replications. The plots consisted of four electrical conductivity levels of the irrigation water (0.3, 1.5, 3.0, and 4.5 dS m-1), and the subplots consisted of three planting systems: DS = direct sowing; TP1 = transplanting of seedlings produced with moderate-salinity water (1.5 dS m-1), and TP2 = transplanting of seedlings produced with low-salinity water (0.3 dS m-1). The following variables were analyzed: vegetative growth, leaf gas exchange, and inorganic solutes. The use of watermelon seedlings produced with moderate-salinity water does not result in higher salt tolerance during the vegetative growth stage. Na+, Cl-, and Ca2+ leaf concentrations increase as the salt stress level is increased, regardless of the planting method. However, plants from seedlings (TP1 and TP2) have higher Na+ and Cl- concentrations when subjected to high salinity levels. The direct sowing method resulted in better performance of growth variables, mainly under low salinity levels.

Effects of eustress induced by low concentrations of salinity on broccoli (<i>Brassica oleracea</i>) and purslane (<i>Portulaca oleracea</i>) microgreens

Most controlled environments utilize municipal water for crop irrigation. Many of these sources exceed the EPA guidelines of &lt;500 mg L⁻¹ total dissolved salts. Issues can arise when tap water with above limit salt concentrations is used for irrigation. Eustress is defined as the use of slight stress (from stressors such as salinity, temperature, or light) to induce positive effects without distress. While eustress is commonly used on mature plants, the effects on early growth stages of plants, such as microgreens, are not well documented. As microgreens are typically more stress sensitive, the concentrations of salinity to induce eustress may be lower than for mature plants. To identify how eustress affects microgreens, salinity concentrations commonly found in tap water were used in these experiments. <italic>Brassica oleracae</italic> (moderately salt tolerant) and <italic>Portulaca oleracea</italic> (highly salt tolerant) microgreens were evaluated. Both species of microgreens were cultivated using salinity irrigation treatments ranging from 0 dS m⁻¹ to 1.5 dS m⁻¹. Plants were analyzed for microgreen yield (fresh weight and dry weight), percent moisture content (%MC), percent dry matter (%DM), vitamin C (T-AsA, AsA) and proline concentrations. The results indicate that yields of both variety remained unaffected by the salinity treatments. However, %MC and proline significantly increased under 1 dS m⁻¹ and 1.5 dS m⁻¹ NaCl in broccoli. Vitamin C also decreased as salinity increased in broccoli microgreens. Purslane microgreen vitamin C and proline remained unaffected by salinity. In conclusion, while low salinity levels had no negative impacts on microgreen yields, there were varied impacts on the phytochemistry between each variety.

Incubating red NIFI strain of tilapia eggs in a closed-water recirculation system with varied salinity levels

This research aims to determine the impact of varying salinities on the hatching of red NIFI tilapia eggs in a closed-water recirculation system incubator. The eggs were hatched at salinities of zero ppt, one ppt, five ppt, and ten ppt, with three replications per treatment. The stocking density for each replication was set at 1,750 eggs per liter. After a six-day incubation period, the resulting larvae were reared under the same salinity conditions for four weeks, with a stocking density of 1,000 individuals per cubic meter. The hatching rate of eggs recorded for the zero ppt salinity treatment was 74%. There was no significant difference between the zero ppt, one ppt (73%), and five ppt (69%) salinity treatments, while the ten ppt (24%) yielded significantly different hatching rates of eggs results (p&lt;0.05). The highest survival rate of reared larvae was achieved in zero ppt salinity treatment, reaching 75%. Salinities of one ppt, five ppt, and ten ppt yielded larvae survival rates of 70%, 55%, and 49%, with statistical significance (p&lt;0.05). Egg hatching in an incubator with a closed water recirculation system at low salinity levels can be considered an initial adaptation step in brackish water tilapia seed production.

Study of different hydrographic variables at Ennore and Chennai fisheries harbour region of Chennai, India

The knowledge of hydrographic variables is very important in determining the abundant availability of fishes in a particular region. The study site selected includes an industrially polluted area, Ennore and Chennai fisheries harbour region. The hydrographic variables selected for study includes temperature, salinity, pH, dissolved oxygen, chlorophyll a, b and c, primary productivity, gross and net and the nutrients, phosphate, ammonia and nitrate. The important hydrographic variables and its effect on the region and that influence the fish abundance throughout the year are discussed. At Ennore, the salinity level was maximum during the month of July, 37.00 ppt at a lowest temperature of 27.00 °C and at a highest temperature of 31.00 °C in the month of Sept’09, the salinity level was 32.00 ppt. At Chennai fisheries harbour, the lowest temperature recorded was 26.40 ºC at Jan’09 and the highest temperature was 30.0 ºC at April’09, lowest salinity level was 26.80 ppt at Feb’09 and highest salinity level was 38.50 ppt at July’09. The variations among months and from 2 different locations viz. Ennore and Chennai Fisheries harbour were studied during the entire year. The interaction effects between the two locations were also studied. Temperature, salinity, chlorophyll a, b and c primary productivity, gross and net are non significant p0.05 at Ennore and at Chennai Fisheries harbour location. The response optimization of the different hydrographic variables viz. temperature, 28.14 °C, salinity, 30.80 ppt, pH, 6.37, dissolved oxygen, 3.12 ml/l, and total soluble solids, 0.40 mg/l for a predicted response of chlorophyll a of 3.35mg/m3 at Ennore and at Chennai Fisheries harbour region the hydrographic variables viz. temperature, 30.00 °C, salinity, 26.80 ppt, pH, 6.38 dissolved oxygen, 2.86 ml/l and total soluble solids of 0.40 mg/l for a predicted chlorophyll a response of 1.88mg/m3 were worked out.

Reduced salinity exacerbates the viral infection on the coccolithophorid Emiliania huxleyi at elevated pCO2

The blooms of coccolithophores are usually terminated by their viruses. However, little has been documented on the interplay between the host with virus under different environmental conditions. We investigated the relationship of Emiliania huxleyi (BOF92) and its virus (EhV99B1) after the coccolithophorid had acclimated to different levels of salinity (S35: 35‰; S25: 25‰) and CO2 (AC: 400 μatm; HC: 1000 μatm) for about 15 generations. Our results showed that the virus infection decreased the growth of E. huxleyi along with decreased photochemical efficiency and photosynthetic carbon fixation under all the combinations of the treatments. Lowered salinity exacerbated the impacts of the viral infection on the growth and photosynthetic performance of E. huxley. The elevated pCO2 appeared to have alleviated the impacts of the viral infection on its photosynthetic performance with enhanced levels of Fv/Fm, by about 49% under S35 and by about 16% under S25, respectively. Nevertheless, the elevated pCO2 enhanced the virus burst size by about 18% under the high and by about 46% under the low levels of salinity, respectively. It is concluded that reduced salinity under the elevated pCO2 exacerbates the impact of the virus on E. huxleyi, leading to the highest burst sizes and the lowest photosynthetic carbon fixation, and the enhanced photochemical efficiency and increased levels of Chl a under the elevated pCO2 could have facilitated the energy supply for the virus multiplication in the infected cells of E. huxleyi.

Minimizing salinity-induced Pb toxicity to microbial N cycling processes in saline Pb-polluted soils amended with biochar

Biochar may affect nitrogen (N) cycling processes and, therefore, plant-available forms of soil N by modifying the activity and composition of the soil microbial community. However, it is unclear how biochar addition can influence microbial N cycling and availability in saline polluted soils. The present study investigated the impact of sugarcane bagasse biochars (SBBs) produced at 400 and 600 °C on potential net ammonification, nitrification and N mineralization, microbial biomass N (MBN), and urease activity in a calcareous soil polluted with lead (Pb) under different levels of NaCl salinity (6 and 10 dS m-1 ) during a 120-day incubation period. NaCl salinity increased soil available Pb concentration, with a greater increase at high than low salinity level. The application of SBBs increased soil organic carbon (SOC, 96–101 % relative to controls), dissolved organic carbon (DOC, 14–110 %), total nitrogen (TN, 6–25 %), cation exchange capacity (CEC, 12–20 %), and immobilized soil Pb (10–25 %). Lead immobilization, which largely resulted from increased soil CEC, was greater with addition of 600 °C (20–25 %) than 400 °C (15–20 %) biochar in saline soils. Addition of SBBs decreased the availability of soil Pb that was enhanced by salinity. Biochar application stimulated potential net ammonification (177–218 %), nitrification (70–83 %) and N mineralization (92–110 %), MBN (114–221 %) and urease activity (66–79 %) in saline Pb-polluted soils. Redundancy analysis revealed that increased DOC, increased TN and Pb immobilization were the most significant factors contributing to the enhanced N bio-transformations, MBN, and urease activity in saline polluted soils amended with SBBs. Our highlights the potential benefits of low-temperature SBBs as an amendment to minimize the impact of metal toxicity associated with salinity on microbial N cycling processes in Pb-polluted soils. In conclusion, biochar application could be a useful practice for enhancing the N turnover rate in saline Pb-polluted soils by increasing substrate availability and decreasing Pb mobility.

Differential impacts of salinity on antibiotic resistance genes during cattle manure stockpiling are linked to mobility potentials revealed by metagenomic sequencing

Livestock manure is an important source of antibiotic resistance genes (ARGs), and its salinity level can change during stockpiling. To understand how the salinity changes affect the fate of ARGs, cattle manure was adjusted of salinity and stockpiled in laboratory microcosms at low (0.3% salt), moderate (3.0%) and high salinity levels (10.0%) for 44 days. Amongst the five ARGs (tetO, blaTEM, sul1, tetM, and ermB) and the first-class integrase (intI1) monitored by qPCR, the relative abundance of tetO and blaTEM exhibited no clear trend in response to salinity levels, while that of sul1, tetM, ermB and intI1 showed clear downward trends over time at the lower salinity levels (0.3% and 3%) but not at the high salinity level (10%). Metagenomic contig construction of cattle manure samples revealed that sul1, tetM and ermB genes were more likely to associate with mobile genetic elements (MGEs) than tetO and blaTEM, suggesting that their slower decay at higher salinity levels was either caused by horizontal gene transfer or co-selection of ARGs and osmotic stress resistant determinants. Further analysis of metagenomic contigs showed that osmotic stress resistance can also be located on MGEs or in conjunction with ARGs.

Chlorophyll fluorescence changes, as plant early state indicator under different water salinity regimes on the invasive macrophyte Elodea canadensis (Michx., 1803)

Analysis of the photosynthetic apparatus provides information on the physiological state of plants. The changes of metabolites in plant cells analysed with the pulsed chlorophyll fluorometer make it possible to determine these changes in plant cells even in the presence of insignificant cell damage. The possible effects of different salinity levels, 0.584, 1.461, 2.922 and 5.844 PSU (denoting Practical Salinity Unit) on the fluorescence properties of the pigment complexes of the aquatic invasive E. canadensis photosynthetic apparatus were investigated. Information about E. canadensis macrophyte photosynthetic systems (PSI and PSII) was obtained. After a prolonged impact, the results indicate that high salinity levels in substrates 2.922 and 5.844 PSU seriously affect plant photosynthetic apparatus inhibition. The decrease in ∆Fv/Fm΄ values at 2.922 and 5.844 PSU indicates general deterioration in macrophytes' physiological state. In the post-stress period, photosynthesis intensified. An interesting feature was noted: a low water salinity level (0.584) stimulates chlorophyll formation and increases the FvFm parameter. The research revealed the influence of salinity levels in the substrate on the photosynthesis processes in plants. The PSII system of submerged macrophytes responds rapidly to high salinity levels, probably due to the inhibition of protein synthesis. These data provide information for further bio-diagnosis of overall plant health and prediction of exposure levels, as well as the ability to make predictions of invasive plant growth and spread. The invasion of this plant macrophyte causes the most serious concern in Europe nowadays.

Castor bean cake increases osmoprotection and oil production in basil (Ocimum basilicum) under saline stress

Water salinity is a major abiotic stress that impacts plant growth and metabolism, reducing crop production. However, the adequate use of organic fertilizers rich in nitrogen (N) can attenuate the damages caused by saline stress. In this context, the castor bean cake (CBC), a co-product of the castor oil production chain, has shown great potential as organic fertilizer and stress mitigator, however, the mechanisms involved in these responses remain unclear. Thus, this study aimed to investigate the effects of different doses of CBC and electrical conductivities of irrigation water (EC) on the photochemical efficiency of photosystem II, the accumulation of organic solutes, and the oil production in basil. The experimental design was randomized blocks in a 5 × 5 factorial scheme, combining levels of EC (0.5, 1.2, 3.0, 4.7, 5.5 dS m−1) with doses of CBC (0.0, 1.4, 5.0, 8.5 and 10 t ha−1), in a matrix generated by the Box Central Compound. The contents of proline, glycine-betaine, proteins, amino acids, reducing sugars, non-reducing sugars, total sugars, photosynthetic pigments, electrolyte leakage, chlorophyll a fluorescence, and oil production were evaluated. The highest photochemical efficiency and oil content was found in basil irrigated with EC up to 3 dS m−1 and supplemented with 5 t ha−1 of CBC, which was followed by lower electrolyte leakage. In addition, CBC induced osmoregulation under saline conditions, as shown by the increase in free amino acids, proteins, proline, glycine-betaine, and sugars. However, high doses of CBC combined with high EC reduced photosynthetic pigment content, chlorophyll a fluorescence, and oil content. In conclusion, CBC induced osmoprotection, maintaining cell membrane integrity and increasing photochemical efficiency of basil. In addition, the use of 5 t ha−1 of CBC combined with low levels of water salinity can be employed to enhance oil production in basil.

Colloidal Stability of CA, SDS and PVA Coated Iron Oxide Nanoparticles (IONPs): Effect of Molar Ratio and Salinity.

Iron Oxide Nanoparticles (IONPs) have received unprecedented interest in various applications. The main challenges in IONPs are fluid stability due to agglomeration in a saline condition. This paper aims to investigate the colloidal stability of citric acid (CA), sodium dodecyl sulphate (SDS) and polyvinyl alcohol (PVA) under various molar ratios and levels of salinity. Firstly, the IONPs were synthesized using a facile co-precipitation approach. Secondly, the IONPs were coated using a simple dip-coating method by varying the molar ratio of CA, SDS and PVA. Next, the coated IONPs were characterized by using an X-ray Diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and a Field Emission Scanning Electron Microscope (FESEM) for the morphological and crystallographic study of coated IONPs. Finally, the coated IONPs were characterized for their zeta potential value and hydrodynamic size using a Zetasizer and their turbidity was measured using a turbidity meter. It was found that at a low salinity level, 0.07 M of CA-IONPs, a high zeta potential value, a smaller hydrodynamic size, and a high turbidity value of -40.9 mV, 192 nm and 159 NTU were observed, respectively. At a high salinity level, 1.0 M SDS-IONPs recorded a high zeta potential value of 23.63 mV, which corresponds to a smaller hydrodynamic size (3955 nm) and high turbidity result (639 NTU). These findings are beneficial for delivering cutting-edge knowledge, especially in enhanced oil recovery (EOR) applications.