Radiation Hazard from Natural Radioactivity in the Marine Sediment of Jeddah Coast, Red Sea, Saudi Arabia

Marine sediment samples were collected along the Jeddah coast, Red Sea, Saudi Arabia, in order to assess radiation hazards and the exposure to human and marine living organisms. Using collaborative techniques, grain size, mineralogical characteristics, and natural radioactivity were investigated. To examine the influence of sediment characteristics over the distribution of the measured radionuclides, resulting data were statistically processed by using multivariate analyses. 238U, 232Th, and 40K levels were specified to be 19.50, 9.38, and 403.31 Bq kg−1, respectively. Radionuclides distributions were affected by sediment mud content, organic matter, and heavy minerals index. The calculated radiation risk parameters are within the safe range and lower than the global average. Natural radiation from these marine sediments is normal and poses no significant radiological risk to the public or marine living organisms. The natural radioactivity of the marine sediment in this Jeddah coastline will have to be monitored on a regular basis to avoid overexposure to the residents.

The coastal ecosystem supports a diverse range of inorganic and bio-resources, many of which, in common fishery, are commercially, culturally, scientific, aesthetically, and recreationally important to the people of the entire region. The study of various bioresources and associated geological processes of the coastal zone improves the proper understanding of the relationship between biotic and non-biotic components and their mutual dependence on maintaining ecosystem integrity [12,13]. Marine sediments play an important role in the ecology and environment of coastal ecosystems and marine environments. They are constantly changing and are the most dynamic part of these ecosystems [14,15]. Numerous marine contaminants, including radionuclides, are stored in marine sediments. Anthropogenic activities have contributed to the radioactivity level in marine ecosystems. Industrial discharges, nuclear accidents, and the discharge of nuclear waste have been recognized as main sources of elevated radioactivity levels in many marine ecosystems [16][17][18]. Lin et al. [19] recorded anthropogenic uranium imprints in the Baltic Sea sediments due to human nuclear-related activities. Al-Qasmi et al. [20] ascribed the enrichment of 238 U, 236 U, and 234 U in the marine sediment from Loch Etive, Scotland, to the for members of the public and marine non-human biota due to exposure to natural radiation. This study will contribute to the radiation data bank of Saudi Arabia.

The Study Area
The study area covers the coastal of Jeddah, Red Sea, Saudi Arabia, between latitudes 20°56′50″ and 21°11′30″ N and longitudes 39°8′40″ and 39°19′40″ E (Figure 1). Jeddah city is considered one of the most significant and largest (1765 km 2 ) urban and industrial areas along Saudi Arabia's Red Sea coastline. It is characterized by an arid climate with sparse rainfall [43,50]. Jeddah is part of the eastern Red Sea shelf region, bordered on land by the rough Arabian Shield mountains. These mountains represent Neoproterozoic basement rocks, which include Precambrian calc-alkaline volcanic, volcaniclastic, intrusive, and metamorphic rocks. Tertiary clastic succession, basaltic lavas, and gabbro dikes cover these basement rocks. Quaternary surficial deposits cover the coastal plain, including coral reefs and carbonate, alluvial deposits, sabkha, and sand dunes [15,51].
The Red Sea is unique among the world's seas in that it has a few permanent streams flowing into it and receives extremely scanty irregular rainfall. Terrigenous sediments are contributed by mostly northwesterly winds and occasional rainstorms. Aeolian and biogenic materials contribute significantly to the marine realm in arid regions such as Saudi Arabia, where riverine sediments are rare or completely absent [50,52].

Sampling and Sample Treatment
Eighteen sampling sites representing the surface marine sediments (0-10 cm depth) were selected for this study (Figure 1). Approximately 500 g of sediment samples was collected during March 2020 using a Van-Veen grab sampler by combining three subsamples from each site. In order to prevent cross-contamination, the collected samples Jeddah is part of the eastern Red Sea shelf region, bordered on land by the rough Arabian Shield mountains. These mountains represent Neoproterozoic basement rocks, which include Precambrian calc-alkaline volcanic, volcaniclastic, intrusive, and metamorphic rocks. Tertiary clastic succession, basaltic lavas, and gabbro dikes cover these basement rocks. Quaternary surficial deposits cover the coastal plain, including coral reefs and carbonate, alluvial deposits, sabkha, and sand dunes [15,51].
The Red Sea is unique among the world's seas in that it has a few permanent streams flowing into it and receives extremely scanty irregular rainfall. Terrigenous sediments are contributed by mostly northwesterly winds and occasional rainstorms. Aeolian and biogenic materials contribute significantly to the marine realm in arid regions such as Saudi Arabia, where riverine sediments are rare or completely absent [50,52].

Sampling and Sample Treatment
Eighteen sampling sites representing the surface marine sediments (0-10 cm depth) were selected for this study (Figure 1). Approximately 500 g of sediment samples was collected during March 2020 using a Van-Veen grab sampler by combining three subsamples from each site. In order to prevent cross-contamination, the collected samples were transferred to new, clean, and labelled plastic jars using a clean stainless-steel shovel. The samples were immediately stored in ice boxes under −4 • C until transportation to the lab. The sediment samples were blended, homogenized, and dried at room temperature before being placed in an electric oven (105 • C; 24 h) to dispose of the moisture and to achieve a constant weight [9,28,32]. These samples were then divided into several portions for various laboratory examinations.

Sediment Granulometry and Mineralogy
Utilizing loss in ignition methods [53], organic matter content (OM%) was determined in the sediment. Following digestion in HCl (1 N), the gravimetric technique was used to calculate CaCO 3 concentrations [54]. Wet sieving was used to calculate the proportions of the different particle size grades (sand 2.00-0.063 mm and mud < 0.063 mm) [55]. Heavy minerals were separated using heavy liquid technique (Bromoform) and examined using a polarizing microscope [56,57]. The mineralogical compositions of the bulk powdered sediment samples were determined by using the X-ray diffraction technique (XRD). The qualitative chemical composition of selected heavy mineral grains were examined utilizing environmental scanning electron microscope (ESEM) and energy dispersive spectrometer (EDS) techniques (SEM/EDX, XL 30 ESEM, Philips Co., Amsterdam, The Netherlands). Extensive technical descriptions of OM% and CaCO 3 %, grain size and heavy minerals determination and the specification of SEX/EDX and XRD instruments are provided in Table S1 (in Supplementary Materials).

Radiometric Analysis
Dried and homogenized marine sediment samples were weighed and instantly placed into a 100 mL plastic standard cylinder and firmly sealed using Teflon tape around their screw necks, and wide Vinyl tape was used around their caps and secured for 30 days until examination. The radiogenic gases 222 Rn and 220 Rn are prevented from escaping by the in-growth of U and Th decay, which additionally allows for secular equilibrium between 238 U, 232 Th, and their decay products [58]. A well-calibrated sodium-iodide and thallium-activated gamma-ray spectrometry scintillation detector (3 × 3 NaI (Tl)) was used to specify the amounts of 238 U ( 234 Th-0.0633 MeV), 232 Th ( 212 Pb-0.2386 MeV) and 40 K (1.461 MeV) activity concentrations in the collected marine sediment samples. This detector is sealed with a photomultiplier tube in aluminum housing. The tube is adequately protected against induced X-rays by a cylindrical copper (0.6 cm thickness) and isolated from environmental radiation by a chamber of lead bricks and lead cover (5 cm). Standard point sources ( 60 Co and 137 Cs) were used to calibrate the detector's energy. Every sample has been counted for 1000 s. Additional details for the exact calculation of the activity concentration can be obtained from the literature [4,5].
Samples preparation, grain size analysis and heavy minerals separation were conducted at the Geology Department, Faculty of Science, Ain Shams University Laboratories. The XRD analysis were carried out at the Central Laboratories Sector of The Egyptian Mineral Resources Authority. SEM/EDX and radiometric analysis were performed at the Egyptian Nuclear Materials Authority.

Calculation of the Radiation Hazard Indices
The radium equivalent activity index (Ra eq ) [1,59], external hazard index (H ex ) [1,60], absorbed dose rate (D) [1], annual effective dose (AEDE) [1], and excess lifetime cancer risk (ELCR) [6,61,62] have all been calculated in order to evaluate the external radiation hazards brought on by the activity concentration of the measured radionuclides in the marine sediment of the Jeddah Coast, Red Sea, Saudi Arabia. Table S2 (in Supplementary Materials) provides an overview of the descriptions and formulas used to calculate external hazard indicators.
The total dose rate (TD) per organism to biota (non-human) in the marine environments was calculated utilizing the ERICA Tool software (ERICA tool version 2.0.185, https://erica-tool.com/, accessed on 3 July 2022) [63]. The ERICA software is a dosimetry model that calculates the internal and external absorbed dose rates to (marine living organisms across a broad range of body masses and habitats for all radioactive elements of concern ( 238 U and 232 Th). The ERICA tool is thoroughly described in the literature [63,64]; more details can be found in Table S1.

Statistical Analyses
To reveal and emphasize the interrelationship between the investigated radionuclide ( 238 U, 232 Th, and 40 K) activity concentrations and sediment properties (grain size, CaCO 3 , OM, and Heavy Minerals index), a multivariate Pearson's correlation coefficient matrix (PCC), hierarchical cluster analysis (HCA) in Q mode, and principal component analysis (PCA) were performed using SPSS (version 21.0, New York, NY, USA) and OriginLab (version OriginPro 2021, Northampton, MA, USA).

Textural Attributes
Findings of grain-size analysis of the collected marine sediment samples are provided in Table 1. Their CaCO 3 contents varied from 6.80 to 62.80%, these sediments are generally rich in carbonate. The organic matter content (OM%) of these sediments ranged from 0.00 to 1.20%. The low OM observed in these sediments can be explained by the deposition of siliciclastic terrigenous materials, which are low in OM or by rapid degradation of recently formed, easily decomposable endogenic biological activity [65]. Compared to mud fraction (silt and clay), sand fractions were found to be dominant in all studied samples (23.00-92.80%). On the other hand, the mud fraction has no clear trend. It is obvious that these sediments are composed mainly of carbonate and sand with minor amounts of mud and OM. The carbonate content in these coastal sediments is sourced from the erosions of carbonate-rich coastal rocks and the mixing of sediments with shell fragments and other calcareous debris [44,66,67]. Table 1. Grain size data, heavy minerals index, and activity concentration of the measured radionuclides.

Sample
No.

Mineralogy
The mineral composition of representative bulk sediment samples ( Figure S1) revealed the dominance of silicate minerals (quartz, albite, and amphiboles) and non-silicate minerals (calcite, aragonite, and gypsum). The heavy minerals indices of the studied marine sediments range from 0.48% and 15.16% (mean 5.81%).
The light minerals fractions of these marine sediments consist mostly of quartz and feldspar grains (mainly albite). Both opaque and non-opaque minerals varieties identified within the heavy mineral assemblage. The opaque minerals are mostly magnetite, ilmenite, and chromite ( Figure 2). The non-opaque minerals assemblages consist of amphiboles, pyroxenes, epidote, zircon, sphene, garnet, monazite, tourmaline, and kyanite ( Figure 3). Andalusite, rutile, and staurolite were recorded in a few samples in minor amounts. Interestingly, monazite grains show U and Th concentrations in their chemical composition ( Figure 4). Monazite is thought to be the primary source of natural radioactivity in marine and beach sand [68][69][70][71][72]

Mineralogy
The mineral composition of representative bulk sediment samples ( Figure S1) revealed the dominance of silicate minerals (quartz, albite, and amphiboles) and nonsilicate minerals (calcite, aragonite, and gypsum). The heavy minerals indices of the studied marine sediments range from 0.48% and 15.16% (mean 5.81%).
The light minerals fractions of these marine sediments consist mostly of quartz and feldspar grains (mainly albite). Both opaque and non-opaque minerals varieties identified within the heavy mineral assemblage. The opaque minerals are mostly magnetite, ilmenite, and chromite ( Figure 2). The non-opaque minerals assemblages consist of amphiboles, pyroxenes, epidote, zircon, sphene, garnet, monazite, tourmaline, and kyanite ( Figure 3). Andalusite, rutile, and staurolite were recorded in a few samples in minor amounts. Interestingly, monazite grains show U and Th concentrations in their chemical composition (Figure 4). Monazite is thought to be the primary source of natural radioactivity in marine and beach sand [68][69][70][71][72].    The heavy mineral assemblages of Jeddah coastal marine sediments are, to a large extent similar, suggesting inheritance from the same source rocks. The nature of these assemblages indicates a variety of probable source rocks, including sedimentary, igneous, and metamorphic, with a relatively short distance of transportation. This explains the distinctly low roundness of the heavy grains ( Figure 3) and the considerable amounts of feldspars grains. The distinctly high proportions of amphiboles and pyroxenes in the marine sediments studied indicate a major role of the surrounding basement. The potential contribution of a metamorphic rock source has pointed to the presence of garnet, kyanite, staurolite, and andalusite [57,73]. These results are consistent with many research studies [52,66,74].   The heavy mineral assemblages of Jeddah coastal marine sediments are, to a large extent similar, suggesting inheritance from the same source rocks. The nature of these assemblages indicates a variety of probable source rocks, including sedimentary, igneous, and metamorphic, with a relatively short distance of transportation. This explains the distinctly low roundness of the heavy grains ( Figure 3) and the considerable amounts of feldspars grains. The distinctly high proportions of amphiboles and pyroxenes in the marine sediments studied indicate a major role of the surrounding basement. The potential contribution of a metamorphic rock source has pointed to the presence of garnet, kyanite, staurolite, and andalusite [57,73]. These results are consistent with many research studies [52,66,74]. The heavy mineral assemblages of Jeddah coastal marine sediments are, to a large extent similar, suggesting inheritance from the same source rocks. The nature of these assemblages indicates a variety of probable source rocks, including sedimentary, igneous, and metamorphic, with a relatively short distance of transportation. This explains the distinctly low roundness of the heavy grains ( Figure 3) and the considerable amounts of feldspars grains. The distinctly high proportions of amphiboles and pyroxenes in the marine sediments studied indicate a major role of the surrounding basement. The potential contribution of a metamorphic rock source has pointed to the presence of garnet, kyanite, staurolite, and andalusite [57,73]. These results are consistent with many research studies [52,66,74]. Table 1 lists the measured activity concentrations of 238 U, 232 Th, and 40 K in the investigated marine sediment. These values are presented by graduated symbols method in Figure 5. The activity concentrations of the measured radionuclide have the order of 40 K > 238 U > 232 Th. The results clearly reveal that the observed concentration of 40 K greatly surpasses those of both 238 U and 232 Th. This indicates that 40 K in common is a more prevalent radioactive element in these marine sediments. Potassium is more abundant in magmatic rocks as a major constituent of several rock-forming minerals than U and Th [75][76][77]. The activity concentration of 238 U, 232 Th, and 40 K varied site-by-site, because the physical, chemical, geochemical, and mineralogical components of the marine sediment vary greatly [78,79]. The mean concentration values of 238 U, 232 Th, and 40 K are 19.50 Bq kg −1 , 9.38 Bq kg −1 , and 403.31 Bq kg −1 ; respectively. These mean values are significantly lower than the world average [6] ( Table 2). The current investigation revealed that 238 U, 232 Th, and 40 K levels in marine sediment of Jeddah coastline are remarkably natural.  Table 1 lists the measured activity concentrations of 238 U, 232 Th, and 40 K in the investigated marine sediment. These values are presented by graduated symbols method in Figure 5. The activity concentrations of the measured radionuclide have the order of 40 K > 238 U > 232 Th. The results clearly reveal that the observed concentration of 40 K greatly surpasses those of both 238 U and 232 Th. This indicates that 40 K in common is a more prevalent radioactive element in these marine sediments. Potassium is more abundant in magmatic rocks as a major constituent of several rock-forming minerals than U and Th [75][76][77]. The activity concentration of 238 U, 232 Th, and 40 K varied site-by-site, because the physical, chemical, geochemical, and mineralogical components of the marine sediment vary greatly [78,79]. The mean concentration values of 238 U, 232 Th, and 40 K are 19.50 Bq kg −1 , 9.38 Bq kg −1 , and 403.31 Bq kg −1 ; respectively. These mean values are significantly lower than the world average [6] ( Table 2). The current investigation revealed that 238 U, 232 Th, and 40 K levels in marine sediment of Jeddah coastline are remarkably natural.  We attempted to compile a recent comparison of natural radiation levels in marine sediment from various regions of Saudi Arabia and those worldwide. Table 2 showed that the mean values of 238 U in the Jeddah marine sediment were lower than that reported in Saudi Arabia and other countries except for the Arabian Gulf [48], Addurrah beach [49], Egyptian Gulf of Suez [23], Egyptian Mediterranean Sea [69], and Turkey [80]. The mean activity concentrations of 232 Th in Jeddah marine sediments were lower than all other locations in the world except for the Arabian Gulf [48], Farasan Island [46], Oman [81], and Turkey [80]. Conversely, the 40 K mean values were higher than all other locations in the world except Addurrah beach [49], Serbia [82], Cyprus [4], and Bangladesh [32]. It is worth noting that U and Th series disequilibria were well documented [31,83]. The presented values of 226 Ra and 228 Ra (

Multivariate Statistical Analyses
A comparative PCC (Table 3) analysis was conducted to pinpoint the direct association between the specific characteristics of the considered marine sediments and 238 U, 232 Th, and 40 K. Correlations of 0.20-0.39, 0.40-0.59, 0.60-0.79, and 0.80-1.00 are considered weak, moderate, strong, and very strong, respectively [87]. 238 U has significant strong positive correlations with mud content (Pearson's R = 0.678) and weak positive correlation with OM (Pearson's R = 0.357), indicating the effect of fine particles and OM on the distribution of 238 U [37]. 238 U has moderate positive correlations with 232 Th (Pearson's R = 0.419), this is due to the co-existence of U and Th radionuclides in nature [69,85,88], which is reflected by the presence of both radioelements in the SEM/EDX of monazite grain (Figure 4). 232 Th has significant strong positive correlations with heavy minerals index (Pearson's R = 0.696). On the other hand, 40 K has moderate positive correlations with sand content (Pearson's R = 0.510). The observed HCA results ( Figure 6) were remarkably similar to the PCC results. It revealed that there are two groups of variables. Cluster (1) is related to 40 K and sand. This suggests that 40 K is more linked with sand in the considered marine sediments. Cluster (2) splits into two subclusters: A ( 238 U, 232 Th, HI , and Mud) and B (CaCO 3 ). This indicates that 238 U and 232 Th are more associated with HI and, to a lesser extent, mud content. In addition, no possible association is noted between CaCO 3 and the measured radionuclides. minerals index (Pearson's R = 0.696). On the other hand, 40 K has moderate positive correlations with sand content (Pearson's R = 0.510). The observed HCA results ( Figure 6) were remarkably similar to the PCC results. It revealed that there are two groups of variables. Cluster (1) is related to 40 K and sand. This suggests that 40 K is more linked with sand in the considered marine sediments. Cluster (2) splits into two subclusters: A ( 238 U, 232 Th, HI, and Mud) and B (CaCO3). This indicates that 238 U and 232 Th are more associated with HI and, to a lesser extent, mud content. In addition, no possible association is noted between CaCO3 and the measured radionuclides.

Radiation Hazard for Humans
The calculated values of the radiological hazard parameters for the investigated marine sediments are shown in Table 4. In order to establish homogeneity with regard to radiation dose from the measured naturally occurring radionuclides, the radium equivalent activity index (Raeq) was calculated [1,59]. The obtained Raeq values ranged from 43.526 to 87.620 Bq kg −1 (mean 63.969 Bq kg −1 ). These levels are considerably below 370 Bq kg −1 , which is the suggested maximum value [1,59]. Gamma radiation from emitting natural radionuclides in the studied marine sediment has an external hazard index (Hex) that ranges from 0.118 to 0.237 (mean 0.173). All calculated Hex values in this investigation are below the safety level of one [60], which is regarded as negligible. Absorbed dose rate (D) is the exposure of an individual to external, terrestrial radiation while engaged in outdoor activity. The calculated D values varied from 21.196 to 42.137 nGy h −1 (mean 31.493 nGy h −1 ). These values were below the world average (57 nGy h −1 ) [1] in all studied marine sediment samples. Figure 8 shows the contributions of 238 U, 232 Th, and 40 K to the obtained D values contained in each sediment sampling site. Evidently, the contribution of 40 K is the greater one, and the contribution of the measured radionuclides in D values varies from one site to another.

Radiation Hazard for Humans
The calculated values of the radiological hazard parameters for the investigated marine sediments are shown in Table 4. In order to establish homogeneity with regard to radiation dose from the measured naturally occurring radionuclides, the radium equivalent activity index (Ra eq ) was calculated [1,59]. The obtained Ra eq values ranged from 43.526 to 87.620 Bq kg −1 (mean 63.969 Bq kg −1 ). These levels are considerably below 370 Bq kg −1 , which is the suggested maximum value [1,59]. Gamma radiation from emitting natural radionuclides in the studied marine sediment has an external hazard index (H ex ) that ranges from 0.118 to 0.237 (mean 0.173). All calculated H ex values in this investigation are below the safety level of one [60], which is regarded as negligible. Absorbed dose rate (D) is the exposure of an individual to external, terrestrial radiation while engaged in outdoor activity. The calculated D values varied from 21.196 to 42.137 nGy h −1 (mean 31.493 nGy h −1 ). These values were below the world average (57 nGy h −1 ) [1] in all studied marine sediment samples. Figure 8 shows the contributions of 238 U, 232 Th, and 40 K to the obtained D values contained in each sediment sampling site. Evidently, the contribution of 40 K is the greater one, and the contribution of the measured radionuclides in D values varies from one site to another.   The annual effective doses (AEDEs) for inhabitants were calculated based on D values. AEDE values ranged from 0.026 to 0.052 mSv yr −1 (mean 0.039 mSv yr −1 ). These values were lower than the worldwide average (0.07 mSv yr −1 ) [1] in all the studied sediment samples. Long-term exposure to ionizing radiation typically leads to further risks described as excess lifetime cancer risk (ELCR). To obtain a better insight of the health effects of external exposure to the measured natural radionuclides in Jeddah coast marine sediments, ELCR factors were calculated using AEDE values. The obtained values ranged from 0.091 × 10 −3 to 0.181 × 10 −3 (mean 0.135 × 10 −3 ). The ELCR-calculated values The annual effective doses (AEDEs) for inhabitants were calculated based on D values. AEDE values ranged from 0.026 to 0.052 mSv yr −1 (mean 0.039 mSv yr −1 ). These values were lower than the worldwide average (0.07 mSv yr −1 ) [1] in all the studied sediment samples. Long-term exposure to ionizing radiation typically leads to further risks described as excess lifetime cancer risk (ELCR). To obtain a better insight of the health effects of external exposure to the measured natural radionuclides in Jeddah coast marine sediments, ELCR factors were calculated using AEDE values. The obtained values ranged from 0.091 × 10 −3 to 0.181 × 10 −3 (mean 0.135 × 10 −3 ). The ELCR-calculated values are lower than the world's average (0.29 × 10 −3 ) [6,61]. This demonstrates that public exposure to the investigated marine sediments in Jeddah coastal area cannot cause cancer over the course of their lives. Figure 9 depicts the GIS-based distribution pattern maps of the calculated radiological risk parameters. are lower than the world's average (0.29 × 10 −3 ) [6,61]. This demonstrates that exposure to the investigated marine sediments in Jeddah coastal area cannot cause over the course of their lives. Figure 9 depicts the GIS-based distribution pattern m the calculated radiological risk parameters. Figure 9. Distribution pattern maps of radiological risk parameters. Figure 9. Distribution pattern maps of radiological risk parameters.

Radiation Hazard for Non-Human Biota
Using the ERICA Tool [63,64], the TD to non-human biota (marine organisms) as a result of exposure to 238 U and 232 Th in Jeddah coast marine sediments was estimated and is displayed in Table 5. As shown, the expected TD values were far below the background dose rates. The estimated TD values from Jeddah coast marine sediments radionuclide concentrations to non-human biota are not considerable biological hazards. The assessed TD values for phytoplankton and polychaete worms were considerably greater than other organisms. This indicates that sediment radioactivity may end up causing phytoplankton and polychaete worms to receive the highest dose rates. As the base of the food chain, phytoplankton can be regarded as a significant bioindicator for continuous monitoring of radiological hazard in aquatic ecosystems [31].

Conclusions
From textural and mineralogical attributes, the Jeddah coastal marine sediments are a mixture of materials of marine and continental origin. These sediments are dominated by sand fraction and CaCO 3 with low OM content. The identified non-opaque heavy minerals are amphiboles, pyroxenes, epidote, zircon, sphene, garnet, monazite, tourmaline, and kyanite with minor amounts of andalusite, rutile, and staurolite. The measured activity concentrations have the order of 40 K > 238 U > 232 Th. The mean concentration values of 238 U, 232 Th, and 40 K are 19.50 Bq kg −1 , 9.38 Bq kg −1 , and 403.31 Bq kg −1 , respectively. The radionuclide distributions were influenced by sediment mud content, organic matter, and heavy minerals index. The calculated Raeq, H ex , D, AEDE, and ELCR are within the safe range and lower than the global average. The estimated TD per organism was far below the background dose rates. Natural radiation from these marine sediments is normal and poses no significant radiological risk to the public or non-human biota. The natural radioactivity of the marine sediment in this Jeddah coastline must be monitored on a regular basis to avoid unnecessary radiation exposure to the residents. Additional studies on natural radioactivity in marine water and other radionuclides level such as 137 Cs could provide improved insights into the status of natural radioactivity in this area. This research can assist regulatory bodies and government agencies in planning for urban and industrial expansion while keeping environmental radiation in mind.

Supplementary Materials:
The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/jmse10081145/s1, Table S1 Extensive technical descriptions of OM % and CaCO 3 %, grain size and heavy minerals determination, and the specification of SEX/EDX and XRD instruments and ERICA tool. Table S2: Summary of the external hazard radiological parameters. Figure S1. X-ray diffractograms of bulk marine sediment samples.