The search for solutions to environmental pollution has been on the increase, with many questions recently as to which marine organisms can bioaccumulate trace elements in the marine ecosystem. ...Cadmium, Cr, Cu, Fe, Mn, Ni, Pb, and Zn concentrations in sediment, seawater, and seagrass compartments (root, rhizome, and leaf blade) were determined at Rabigh lagoon, Red Sea. This is to provide an insight into the potential of
Cymodocea serrulata
to bioaccumulate trace elements and as a good candidate to biomonitor these elements in a natural aquatic ecosystem. Results revealed significant variations in trace element concentrations across the three compartments of
C. serrulata
and the sites, with site S8 located in the most closed part of the lagoon recording the highest concentrations for all the trace elements. The translocation factor (
TF
rhizome/root
= 1.00) of trace elements was higher in the root compartment. This implies that the root compartment is a better bioindicator of trace elements and has more potential to be utilized for biomonitoring. A significant positive correlation (
p
< 0.01) was established between the trace element concentrations in sediment, seawater, and the three compartments of
C. serrulata
except for Mn concentration in the compartments. The seagrass
C. serrulata
can be used for biomonitoring of trace elements in marine ecosystems as our results provide information on its capacity to bioaccumulate these elements. This is one of the key characteristics of a typical bioindicator of aquatic pollutants.
Elemental ratios (δ13C, δ15N and C/N) and carbon and nitrogen concentrations in macrophytes, sediments and sponges of the hypersaline Al-Kharrar Lagoon (KL), central eastern Red Sea coast, were ...measured to distinguish their sources, pathways and see how they have been influenced by biogeochemical processes and terrestrial inputs. The mangroves and halophytes showed the most depleted δ13C values of -27.07±0.2 ‰ and -28.34±0.4 ‰, respectively, indicating their preferential 12C uptake, similar to C3-photosynthetic plants, except for the halophytes Atriplex sp. and Suaeda vermiculata which showed δ13C of -14.31±0.6 ‰, similar to C4-plants. Macroalgae were divided into A and B groups based on their δ13C values. The δ13C of macroalgae A averaged -15.41±0.4 ‰, whereas macroalgae B and seagrasses showed values of -7.41±0.8 ‰ and -7.98 ‰, suggesting uptake of HCO3- as a source for CO2 during photosynthesis. The δ13C of sponges was -10.7±0.3 ‰, suggesting that macroalgae and seagrasses are their main favoured diets. Substrates of all these taxa showed δ13C of -15.52±0.8 ‰, suggesting the KL is at present a macroalgae-dominated lagoon. The δ15N in taxa/sediments averaged 1.68 ‰, suggesting that atmospheric N2-fixation is the main source of nitrogen in/around the lagoon. The heaviest δ15N (10.58 ‰) in halophytes growing in algal mats and sabkha is possibly due to denitrification and ammonia evaporation. The macrophytes in the KL showed high C %, N %, and C/N ratios, but this is not indicated in their substrates due possibly to a rapid turnover of dense, hypersaline waters carrying most of the detached organic materials out into the Red Sea. The δ13C allowed separation of subaerial from aquatic macrophytes, a proxy that could be used when interpreting paleo-sea level or paleoclimatic changes from the coastal marine sediments.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A quantitative analysis of coccoliths is presented in 18 core-top samples ranging between 26° N and 21° N and covering two major deep brine pools in the northern part of the Red Sea. Non-brine sites ...are characterized by rich coccoliths that may reach up to 3.31 × 10
9
coccoliths/g made by 22 species, whereas brine sites of Shaban and Kebrit Deeps with additional two non-brine sites are characterized by a decline in coccoliths/g (3.25 × 10
8
coccoliths/g), Shannon diversity, CaCO
3
(%), and high TOC (%). Carbonate dissolution, inferred by qualitative observation and quantitative indices, was only observed at one brine site GeoB7828 in Kebrit Deep. This suggests that the decline in coccolith assemblages may not entirely be attributed to carbonate dissolution. The major decline, however, is probably related to the suspension of fecal pellets and marine aggregates containing delicate coccolith shields within a nepheloid layer and subsequently grazed by zooplankters in which reduced the numbers of coccolith that reached the bottom of the brine sites, or alternatively a deep-sea flow current that carried and remobilized some suspended particles outside the brine pool. Latitudinal fluctuations of eutrophic/oligotrophic coccoliths suggest profound trophic changes in the photic zone in the northern part of the Red Sea.
C. braarudii,
a valuable nutrient-indicator species is here reported for the first time, along with
G. oceanica, H. carteri
as well as biogenic opal dominating the assemblage between 26° N and 24° N, suggesting elevated nutrient conditions and supporting recent high chl-
a
records, whereas areas between 21° N and 23° N lie under oligotrophic conditions due to the presence of
U. sibogae
,
U. tenuis
,
R. clavigera
,
F. profunda
, and
S. pulchra
.
Regional anesthesia for geriatric population Al Harbi, Mohammed; Alshaghroud, Salah; Aljahdali, Mohammed ...
Saudi journal of anaesthesia,
10/2023, Letnik:
17, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Advancements in modern health care over 20 years have substantially increased the average lifespan in developed countries, and the fastest growing population is the elderly population. The proportion ...of people in Saudi Arabia aged 60 or more is predicted to be 25 percent of the total population of 40 million by the end of 2050. Moreover, the number of people aged 80 or more is expected to reach 1.6 million or 4 percent of the total population in the same period. Improvements in surgical techniques, anesthesia, and intensive care units make surgical interventions in older and sicker patients possible. It is estimated that over half of the population older than 65 years will require surgical intervention at least once during the remainder of their lives. Therefore, elderly patients are becoming an even larger part of anesthetic practice. Regional anesthesia (RA) is frequently used in elderly patients, especially during orthopedic surgery, genitourologic and gynecologic procedures, and hernia repair. Although age can no longer be considered a contraindication to anesthesia and surgery, anesthesia-related morbidity and mortality remain higher among elderly than among young adult surgical patients. Undoubtedly, peripheral nerve (PN) blocks improve analgesia and reduce opioid consumption and their associated side effects. This is beneficial in the perioperative care of elderly patients who may have less physiologic reserve to withstand the side effects of general anesthesia (GA).
Rare earth element fractionation and distribution in the coastal ecosystem have been of significant concern and are recognized worldwide as emerging micro-pollutants. However, unlike other metals ...such as trace elements, little is known about their uptake by aquatic plants such as the mangrove Avicennia marina, especially in the central Red Sea. We investigated the fractionation of rare earth elements in six mangrove ecosystems in the central Red Sea and bioavailability in mangrove A. marina. The concentrations of rare earth elements, sediment grain sizes, multi-elemental ratios, geo-accumulation index (Igeo) and bioconcentration factor (BCF) vary significantly (p < 0.05) across the six mangrove ecosystems. Higher concentrations of rare earth elements were recorded at Al Lith (LT) (101.53 mg/kg) and South Jeddah (SJ) (73.38 mg/kg) mangrove ecosystems. However, multi-elemental ratio R(M/L) reveals positive values. In contrast, multi-elemental ratio R(H/M) reveals negative values corresponding to fractionation patterns enriched with medium rare earth elements and heavy rare earth elements depletion across the six mangrove ecosystems. BCF values for rare earth elements were <1, but Lutetium (0.32) had the highest BCF among the rare earth elements, suggesting an efficient accumulation of Lutetium than any other rare earth elements. The scale of Igeo revealed strong contamination (4 ≤ Igeo ≥ 5) of sediment with Lanthanum, Cerium, Praseodynium, Samarium, Godolinium, Holmium, Erbium, Ytterbium, and moderate contamination with Thulium, Terbium, and Dysprosium (1 ≤ Igeo ≤ 3). Principal component analysis showed that clay silt sediment grain size influences rare earth element concentrations in the central Red Sea. Our results provide new evidence for rare earth element fractionation and accumulation in sediment and the potential use of mangrove A. marina for rare earth element monitoring in mangrove ecosystems in the central Red Sea.
Normalized difference vegetation index (NDVI) is one of the parameters of vegetation that can be studied by remote sensing of land surface with Sentinel-2 (S-2) satellite image. The NDVI is a ...nondimensional index that depicts the difference in plant cover reflectivity between visible and near-infrared light and can be used to measure the density of green on a piece of land. On the other hand, the dual-pol radar vegetation index (DpRVI) is one of the indices studied using multispectral synthetic aperture radar (SAR) images. Researchers have identified that SAR images are highly sensitive to identify the buildup of biomass from leaf vegetative growth to the flowering stage. Vegetation biophysical characteristics such as the leaf area index (LAI), vegetation water content, and biomass are frequently used as essential system parameters in remote sensing data assimilation for agricultural production models. In the current study, we have used LAI as a system parameter. The findings of the study revealed that the optical data (NDVI) showed a high correlation (up to 0.712) with LAI and a low root-mean-square error (0.0296) compared to microwave data with 0.4523 root-mean-square error. The NDVI, LAI, and DpRVI mean values all decreased between 2019 and 2020. While the DpRVI continued to decline between 2020 and 2021, the NDVI and LAI saw an increase over the same period, which was likely caused by an increase in the study area’s average annual rainfall and the cautious stance of the Red Global (RSG) project on sustainability.
Mangrove ecosystems are some of the most productive and important sinks for sediment globally. Recently, there has been an increasing interest in possible causes of stress in mangroves, such as ...nutrient limitation, high salinity, solar radiation and temperature. We measured different factors casing stress and determined how they influenced oxidative stress and growth biomarkers in six study sites dominated by mangroves; Al Lith, South Jeddah, Dahban, Thuwal, Rabigh and Mastorah. Significant differences (P < 0.05) were recorded in water salinities and temperatures, nitrogen and phosphorus content in sediments, and antioxidant enzyme activities in different study sites. The highest salinity (40.75 ‰) and temperature (29.32°C) were recorded in the Rabigh mangrove stand, which corresponds to the lowest dissolved oxygen (5.21 mg/L). Total organic carbon, total nitrogen and total phosphorus in sediment across the study areas were in the order Rabigh>Thuwal>Dahban>Al Lith>South Jeddah>Mastorah. Total nitrogen in mangrove leaves at Rabigh was the highest and about 1.3 times higher than the total nitrogen in South Jeddah mangrove ecosystem, very different from the ratio of total nitrogen in the sediments at Rabigh and South Jeddah mangrove ecosystems. The average values of δ13C (-17.60‰) and δ15N (2.84‰) in the six mangrove ecosystems, and the highest δ13C (-13.62‰) and δ15N (4.39‰) at Rabigh in the sediments suggest that nutrient input differed among study sites. Higher nutrient levels at Rabigh mangrove ecosystem were attributed to restricted circulation, camel grazing and land runoff with agricultural waste during seasonal flooding events. However, N limitation and possibly salinity contributed to stress in Al Lith, South Jeddah, Dahban, Thuwal, Rabigh, and Mastorah mangrove ecosystems. Salinity (r = 0.9012) contribute more to stress at Rabigh.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Rabigh is a thriving coastal city located at the eastern bank of the Red Sea, Saudi Arabia. The city has suffered from shoreline destruction because of the invasive tidal action powered principally ...by the wind speed and direction over shallow waters. This study was carried out to calibrate the water column depth in the vicinity of Rabigh. Optical and microwave remote sensing data from the European Space Agency were collected over 2 years (2017–2018) along with the analog daily monitoring of tidal data collected from the marine station of Rabigh. Depth invariant index (DII) was implemented utilizing the optical data, while the Wind Field Estimation algorithm was implemented utilizing the microwave data. The findings of the current research emphasis on the oscillation behavior of the depth invariant mean values and the mean astronomical tides resulted in
of 0.75 and 0.79, respectively. Robust linear regression was established between the astronomical tide and the mean values of the normalized DII (
= 0.81). The findings also indicated that January had the strongest wind speed solidly correlated with the depth invariant values (
= 0.92). Therefore, decision-makers can depend on remote sensing data as an efficient tool to monitor natural phenomena and also to regulate human activities in fragile ecosystems.
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