Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania

Melchior Ludovick Mungubariki; Mwingereza John Kumwenda; Innocent Jimmy Lugendo

doi:doi:10.11648/j.aas.20261103.18

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Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania

Melchior Ludovick Mungubariki^*

, Mwingereza John Kumwenda

, Innocent Jimmy Lugendo

Published in Advances in Applied Sciences (Volume 11, Issue 3)

Received: 27 June 2026 Accepted: 11 July 2026 Published: 18 August 2026

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Abstract

Environmental radioactivity monitoring is essential for assessing potential exposure risks to humans and marine ecosystem, particularly in coastal marine areas where anthropogenic and natural radionuclides may accumulate. However, research studies on natural radioactivity in Tanzania's coastal marine areas remain scarce. This study was therefore conducted to assess the radioactivity levels of natural radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in marine sediments and fish samples from the Tanzanian coastal areas, and to estimate the associated radiological health hazards for both humans and marine ecosystem. A total of 49 samples comprising both sediment and fish were randomly collected from 12 coastal sites and composited for analysis. Radioactivity concentrations were measured using gamma spectrometry. For fish samples, the mean activity concentrations were 4.9 ± 1.9 Bq kg⁻¹ dry weight (dw) for ²²⁶Ra, 488.8 ± 34.1 Bq kg⁻¹ dw for ⁴⁰K, while ²³²Th was below the detection limit. In sediments, the corresponding mean values were 15.1 ± 2.2, 14.9 ± 2.0, and 320.8 ± 27.4 Bq kg⁻¹ dw for ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively. Based on these data, a comprehensive set of radiological hazard indices was computed, including radium equivalent activity (Raₑq), absorbed dose rate (D), annual effective dose equivalent (Eₑff), external and internal hazard indices (Hₑₓ and Hᵢₙ), representative gamma index (Iᵧ), annual gonadal dose equivalent (AGDE), excess lifetime cancer risk (ELCR), and annual effective dose (AED). The results showed that the computed total annual effective committed dose for fish consumption was below the 1 mSv y⁻¹ as recommended by the ICRP, although the mean ⁴⁰K activity in fish exceeded the global average of 420 Bq kg⁻¹. All evaluated hazard indices (Ra_eq, H_ex, D, E_eff, I_γ, AGDE, and ELCR) for sediments, as well as Hᵢₙ and ELCR for fish, were within permissible levels values. In conclusion, the current radioactivity levels in the studied coastal area do not pose a significant radiological risk to human health or the marine ecosystem. Nevertheless, it is advisable to keep monitoring for purpose of detecting any future changes due to natural or anthropogenic influences.

Published in	Advances in Applied Sciences (Volume 11, Issue 3)
DOI	10.11648/j.aas.20261103.18
Page(s)	121-138
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Natural Radioactivity, Gamma Spectrometry, Fish, Marine Sediments, Radiological Hazards Indices, 226Ra, 40K, Tanzania Coastal Areas

1. Introduction

Coastal areas are in many cases considered highly favorable for various socio-economic activities including manufacturing, mining, agriculture, oil and gas exploration, tourism and fisheries

[1, 2]

. It is for this reason coastal areas are generally highly populated. Because of the large population coupled with different economic activities, these areas are prone to environmental pollution caused by organic, chemicals and mineral contaminants produced from the economic activities

[3]

. Among the chemical contaminants of concern are the radionuclides. These are elements that reside in different environments including soil, underground water, marine sediment, sand beach and biota (both flora and fauna).

Although radionuclides are naturally present in the environment at low concentrations, their concentration may be significantly escalated by the release of radioactive wastes from different economic activities

[4, 5]

. The released radionuclides may enters the marine environment directly or indirectly through different pathways, including rivers and rainwater which discharge the waste into the sea. It follows that, radionuclides in the coastal areas may be classified as primordial, cosmogenic and anthropogenic radionuclides. Anthropogenic radionuclides mostly originate from socio-economical activities such as gas and oil production, fertilizer production, mineral exploration and mining

[6, 7]

. Anthropogenic radionuclides may also originate from activities like nuclear tests and operation of nuclear reactors. Nuclear reactor accidents, such as those of Chernobyl (1986) and Fukushima (2011) that happened in the past are also a considerable source of anthropogenic radionuclides

[8]

The presence of radionuclides, irrespective of their category, in the environment may lead to radiation exposure to both human beings and animals

[4, 9]

. According to UNSCEAR (United Nations Scientific Committee on the Effect of Atomic Radiation)

[10]

, natural radionuclides contribute the largest share of radiation exposure to the world population, giving an average annual effective dose of about 2.4 mSv. Of this, decay series radionuclides (mainly from the Uranium (²³⁸U) and Thorium (²³²Th) series, including radon and its progeny) contribute roughly 70-80% of the total dose, while primordial radionuclides such as Potassium (⁴⁰K) account for about 15-20%. Continuous exposure to ionizing radiation may pose serious harmful biological effects such as DNA (deoxyribonucleic acid) damage or cancer

[11, 12]

. Hence, there is need to monitor and control the concentrations of radionuclides in the environment in order to maintain the safety of populations.

As coastal areas host large populations, it is important to have a clear knowledge of the concentrations and distribution of radionuclides in the seafood, soil, water, air and sediments

[6, 13]

. Although the distribution and level of natural radionuclides has been studied widely over the world, a few studies are available in sub-Saharan Africa focusing heavily on countries bordering the Mediterranean and Red seas

[14-16]

. In Tanzania no data on radionuclide pollution have been published along the coastal areas except some studies that have been reported on radioactivity focus on soils, surface water, fish and foodstuff around mining and phosphate industries

[17-21]

. This lack of data hinders the development of an effective regulatory framework for radiation protection in this study area.

Tanzania’s coastal area has recently been experiencing rapid changes due to urbanization and industrialization in such way there is a significant increase of buildings and road construction as well as the use of fertilizer and pesticides in farming

[22, 24]

. Also, activities like mining, gas and oil exploration and production have all increased significantly. Despite the economic benefits of these activities, it is envisaged that the generation of solid wastes in coastal areas will reach about 26 million tons by the end of 2030

[23]

. This implies that there some possibility of elevation of radioactivity concentrations in the marine environment, which may lead to detrimental effect to the coastal habitats. Therefore, monitoring the radioactivity pollution in these areas is of paramount importance in order to ensure the population safety. Hence, this study is set to assess the radioactivity levels and the associated radiological risks in Tanzania’s coastal marine environment and then estimating the annual effective dose due to consumption of fish. Understanding the radiological risk associated with anthropogenic activities and annual effective dose due to consumption of fish is essential for improving safety measures and environmental practices. Also the result of this study will help the regulatory bodies in formulating radiation protection policies and determine the suitability of using sediments material for various applications.

2. Materials and Methods

2.1. Study Area

Tanzania coastal area covers a distance of over 800 km stretching from latitude 4^° 49' S to latitude 10^° 28' S and respective longitudes 38^°and 42^°E as shown Figure 1. The study area is characterized with primarily of Mesozoic to Cenozoic sedimentary rocks basins (sandstone, shale limestone). The sedimentary rocks, vary in age from Jurassic, cretaceous to tertiary and quaternary. Also, the study area is featured shallow, unconfined, and semi-confined alluvial and limestone aquifer with vulnerable to saltwater intrusion and major river deltas. The drainage pattern is of perennial and seasonal rivers draining into the Indian Ocean basin. The major rivers including Pangani, Wami, Ruvu, Rufiji and Ruvuma. The other small rivers are Matandu, Mbwemkuru, Lukuledi, and Msimbazi

[25]

. Other features of the study area include estuaries, mangrove forests, coral reefs, sandy beaches, cliffs, seagrass beds and muddy tidal flats. The study area is also characterized by three big ports which are Dar es Salaam port, Tanga port and Mtwara port as displayed in Figure 1. This area was of interest to this study because of the activities in the region. For instance along rivers Wami, Ruvu and Pangani there are a big farms of rice, maize and other crops. Meanwhile, natural gas extraction is taking place at Songosongo Island in Lindi region, as well as Mnazi Bay and Madimba in Mtwara region. These activities produce wastes that are discharged to marine environments through rivers such as Matandu, Mbwemkuru, Lukuledi and Ruvuma. Besides, all industries operating in Dar es Salaam, Tanga, Lindi and Mtwara are discharge their waste to marine areas through either of the mentioned rivers.

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Figure 1. Map of the Coastal area of Tanzania showing the sampling Stations (Source: IRA GIS Lab).

2.2. Sample Collection and Preparation

A total of 49 samples were first randomized to minimize impartiality and then composited to reduce objectivity and then manageable samples were collected under the study area. Out of these, 12 fish samples were randomly collected from fishermen in the fishing areas around ferries at Dar es Salaam, Tanga and Mtwara. Table 1 shows the fish species names and their sources.

Table 1. The sampled fish species and their source.

S/No.	Species Name	Common name	Local name	Sample Code	Source
1	Scarus Sordidus	Parrot fish	Pono	F 001	Marine water
				FT 002	Marine water
				FM 002	Marine water
2	Epinephelus Caeruleopunctatus	Grouper fish	Chewa	F 002	Marine water
				FT 001	Marine water
				FM 003	Marine water

3	Panaeus Monodon	Prawns	Kamba Mti	F 003	Marine water
				FT 003	Marine water
				FM 001	Marine water

4	Caranx Melampygus	Jack Fish	Kolekole	F 004	Marine water
				FT 004	Marine water
				FM 004	Marine water

Meanwhile, 37 sediment samples were randomly collected from estuaries, sewage pipelines, areas around ports and ocean during low tide. These samples were collected along the coastline at points separated by a distance of 200 m. Each sample was collected at a depth of 5 - 10 cm using open end stainless-steel hand-held Auger corer with a 70 mm diameter. Table 2 shows the sediment samples with their identity and locations. One should note that, in some areas samples were not collected due to several challenges at the sites.

Table 2. Samples Identity and locations in Estuaries, Sewage discharge and Port areas along the Coastal Marine areas of Tanzania.

S/No.	Sample Code	Type of Sample	Location
1	F 001	Fish	Dar es Salaam Ferry
2	F 002	Fish	Dar es Salaam Ferry
3	F 003	Fish	Dar es Salaam Ferry
4	F 004	Fish	Dar es Salaam Ferry
5	FT 001	Fish	Deep Sea Tanga Ferry
6	FT 002	Fish	Deep Sea Tanga Ferry
7	FT 003	Fish	Deep Sea Tanga Ferry
8	FT 004	Fish	Deep Sea Tanga Ferry
9	FM 001	Fish	Mtwara Ferry
10	FM 002	Fish	Mtwara Ferry
11	FM 003	Fish	Mtwara Ferry
12	FM 004	Fish	Mtwara Ferry
13	E6 001	Sediments	Upper Msimbazi River
14	E6 002	Sediments	Down Msimbazi River
15	E6 003	Sediments	Midpoint Msimbazi & Ocean
16	E6 004	Sediments	Upper Msimbazi River
17	E6 005	Sediments	Along the Ocean
18	E7 001	Sediments	Midpoint Mzinga & Kizinga
19	E7 002	Sediments	Upper Mzinga river
20	E7 003	Sediments	Upper Kizinga river
21	SWP 001	Sediments	Sewage discharge point Dar
22	SWP 002	Sediments	Sewage discharge point Dar
23	SWP 003	Sediments	Sewage discharge point Dar
24	SWP 004	Sediments	Sewage discharge point Dar
25	DP 001	Sediments	Dar port near Ferry
26	DP 002	Sediments	Dar port near Ferry
27	DP 003	Sediments	Dar point near Ferry
28	E1 001	Sediments	Midpoint Pangani & Ocean
29	E1 002	Sediments	Down Pangani river
30	E1 003	Sediments	Down Pangani river
31	E1 004	Sediments	Upper Pangani river
32	SWPT 001	Sediments	Sewage discharge point Tanga
33	SWPT 002	Sediments	Sewage discharge point Tanga
34	SWPT 003	Sediments	Sewage discharge point Tanga
35	SWPT 004	Sediments	Sewage discharge point Tanga
36	SWPT 005	Sediments	Sewage discharge point Tanga
37	TP 001	Sediments	Baggage point at Tanga port
38	TP 002	Sediments	Dredging area at Tanga port
39	TP 003	Sediments	Dredging area at Tanga port
40	TP 004	Sediments	Dredging area at Tanga port
41	TP 005	Sediments	Dredging area at Tanga port
42	E4 001	Sediments	Upper Matandu river
43	E4 002	Sediments	Down Matandu river
44	E4 003	Sediments	Midpoint Matandu & Ocean
45	E4 004	Sediments	Upper Matandu river
46	MP 001	Sediments	Mtwara Ferry near port
47	MP 002	Sediments	Mtwara Ferry near port
48	MP 003	Sediments	Mtwara Ferry near port
49	MP 004	Sediments	Mtwara Ferry at cargo point

All these samples were packed in air tight polyethylene bags, stored in ice box and transported to TAEC (Tanzania Atomic Energy Commission) laboratories for preparation and analysis. The sediments samples were air dried under shade for about seven hours then dried in an automatic oven for about three days at a temperature 80°C until constant weight was reached, in order to evaporate water until only the dried sediment remained. Then, the samples were ground with machine and cleaned with acetone to avoid contamination; then sieved to powder of 500 µm grain size. The samples were then weighed and packed in well labelled and air tight canisters of a specific geometry (100mm diameter and 40 mm in height) similar to that of the calibration source provided by IAEA (International Atomic Energy Agency). All the canisters containing samples were then stored for 30 days for uranium and thorium radionuclide daughters to attain secular equilibrium between short- lived and respective long-lived (²²⁶Ra from ²³⁸U) and (²²⁸Ra from ²³²Th) before gamma spectrometric analysis

[26]

. The guidelines regarding the measurement of radionuclides in food and the environment were observed throughout, as guided by IAEA

[27]

In the case of fish samples, the collected fishes were of approximately the same size and identified with the help of ferry fishery officers and fishermen. First, fish samples were melted naturally at room temperature, then rinsed using deionized water. Afterwards, each fish was dissected to remove edible tissues. The tissues were air-dried and then oven-dried at a temperature of 80°C for about three days until they reached constant weight (to ensure that they were completely dried). The dry samples were now ground using an agate mortar before being sieved to powder of 500 µm grain size mesh to obtain homogeneous fish powder

[26]

. Thereafter, the samples were weighed and packed in clean canisters with a specific geometry similar to that of the calibration source provided by the IAEA. They were well labelled then closed tightly with cello tape to prevent radon from escaping. Samples were then stored for 30 days so that uranium and thorium radionuclide daughters could attain secular equilibrium between short- lived progeny and the respective long-lived (²²⁶Ra from ²³⁸U) and (²²⁸Ra from ²³²Th) before gamma spectrometric analysis

[27]

. After 30 days, all the samples were analyzed to determine the activity concentrations of radionuclides using the HPGe (High - Purity Germanium) gamma spectrometry as well.

2.3. Sample Analysis

After 30 days, all the samples were analyzed to determine the activity concentrations of the present radionuclides. This was accomplished by using p-type coaxial high-purity germanium detector (ORTEC®GEM40-83SMP) inside lead shielding and connected to a multichannel analyzer. The detector, with 40% relative efficiency and specific energy resolutions, was calibrated with a CBSS2 multi-nuclide standard source which containing ²⁴¹Am, ¹⁰⁹Cd, ¹³⁹Ce, ⁵⁷Co, ⁶⁰Co, ¹³⁷Cs, ¹¹³Sn, ⁸⁵Sr, ⁸⁸Y, and ⁵¹Cr. The data acquisition and analysis were performed using an ORTEC®DSPEC-LF digital signal processor. The Gamma Vision® software was used in spectrum analysis

[28]

The specific activity concentration of ²²⁶Ra radionuclide in sample was estimated using the 351.9 keV photo peak from the decay of ²¹⁴Pb as well as the 609.3 keV, 1120.3 keV, 1728.6 keV and 1764 keV photo peaks from the decay of ²¹⁴Bi. Likewise, the activity concentration of ²³²Th radionuclide was estimated using the 911.2 keV photo peak from the decay of ²²⁸Ac and the 583.1.6 keV photo peak from the decay of ²⁰⁸Tl. Finally, the activity concentration of ⁴⁰K was determined using the 1460.8 keV photo peak. The actual time used for measurement of every sample was 172800 seconds. Therefore, activity concentration for each radionuclide of interest was computed using equation (1).

Data analysis was performed using gamma vision software and Origin Pro 2018 64-bit software through descriptive approach whereby means, standard deviation and charts/graphs were used in describing the data pattern to meet the objective of the study. Further, inferential analysis was done using an independent sample t-test in comparing means at the significance level of 0.05.

3. Analytical Methods

3.1. Activity Concentration and Uncertainty of the Activity

The activity concentrations (A_s) of the natural radionuclides of interest in this work were computed using equation (1)

[29]

A_s(Bqkg^-1) = C_n/ ƐP_γM_s(1)

where: C_n is the net counting rate under the corresponding peak,

ε

is the detector efficiency at the specific gamma-ray energy, P_γ is the absolute transition probability of the specific gamma-ray and M_s is the mass of the sample (kg). The obtained values of activity concentrations were then used to compute other analytical parameters as discussed here.

3.2. Radium Equivalent Activity (Raeq)

Radium equivalent activity (Ra_eq) is the most widely used for radiation hazard index and common used to assess the consistency of radiation exposure. Ra_eqis a weighted sum of activities of the three natural radionuclides in fish and sediment based on the estimation that 370 Bqkg^-1 of ²²⁶Ra, 259 Bqkg^-1 of ²³²Th and 4810 Bqkg^-1 of ⁴⁰K will produce the gamma-ray dose rate. Ra_eq was computed using equation (2)

[30]

Ra_eq(Bqkg^-1) = A_Ra+ 1.43A_Th+ 0.077A_K(2)

where: A_Ra, A_Thand A_k are activity concentrations (Bqkg^-1) of ²²⁶Ra, ²³²Th and ⁴⁰K respectively.

3.3. Absorbed Gamma Dose Rates

The absorbed gamma dose rate (D) is the index used to describe the intensity of the energy deposited in a small amount of a tissue anywhere in the body and is used to assess the potential damage to a particular organ, tissue or material. The absorbed gamma dose rates due to gamma radiations in air at 1m above the ground surface for the uniform distribution of the naturally occurring radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) was calculated using equation (3) based on guidelines provided by UNSCEAR for fish and sediments samples

[4]

. The conversion factors used to compute the absorbed gamma dose rate in air per unit activity concentration in Bq/kg (dry weight) corresponds to 0.427nGy/h for ²²⁶Ra, 0.623nGy/h for ²³²Th and 0.043 nGy/h for ⁴⁰K.

D (nGyh^-1) = 0.427A_Ra+ 0.623A_Th+ 0.043A_k(3)

where: A_Ra, A_Thand A_k are activity concentrations (Bqkg^-1) of ²²⁶Ra, ²³²Th and ⁴⁰K respectively.

3.4. External and Internal Hazard Index

The external hazard index was calculated from Ra_eq expression through assumption that its maximum allowed value (equal to unity) matches the upper limit of Ra_eq (370 Bqkg^-1) for safe use. The external hazard index (H_ex) is used to indicate the significance of external radiation exposure while internal hazard index (H_in) is used to assess the hazardous effects to the human respiratory organ through inhalation process. So both index are used to predict the effect of radiation on human health and should be less than unity for the purpose of keeping the radiation hazard insignificant. In this work, the external hazard index (H_ex) was computed using Equation (4) while the internal hazard index (H_in) was computed using equation (5)

[31]

H_ex= A_Ra/370 + A_Th/259 + A_K/4810(4)

H_in= A_Ra/185 + A_Th/259 + A_K/4810(5)

where: A_Ra, A_Thand A_k are activity concentrations in (Bqkg^-1) of ²²⁶Ra, ²³²Th and ⁴⁰K respectively.

3.5. Representative Gamma Level Index

Representative gamma level index (I_γ) was used to examine the level of gamma radiation hazard associated with the characteristics radionuclides in the sediment samples collected in the coastal marine areas of Tanzania. Addition, gamma level index normally help to indicate the radiological safety of the building materials and must be equal or less than unity for low to negligible level of radiation exposure

[32]

. This index was computed using equation (6)

[33]

I_γ= A_Ra/150 + A_Th/100 + A_K/1500(6)

where: A_Ra, A_Thand A_k are activity concentrations (Bqkg^-1) of ²²⁶Ra, ²³²Th and ⁴⁰K respectively.

3.6. Annual Gonadal Dose Equivalent

The AGDE (Annual gonadal dose equivalent) is the radiation index used to assess potential radiation effect to gonads since are more relative sensitive to ionizing radiation when you compare to other organs of the body and hence they are considered to be at a high risk of radiation exposure

[34]

. The AGDE was computed using equation (7) to estimate the potential radiation dose that gonads may receive from ²²⁶R, ²³²Th and ⁴⁰K

[7, 35]

AGDE (nGyh^-1) = 0.3.09A_Ra+ 4.18A_Th+ 0.314A_k(7)

where: A_Ra, A_Thand A_k are activity concentrations in Bqkg^-1 of ²²⁶Ra, ²³²Th and ⁴⁰K respectively.

3.7. Annual Effective Dose Equivalent

The annual effective dose equivalent (E_eff) is another parameter which define the radiation hazards. The E_effwas computed from absorbed dose by applying the dose conversion factor of 0.7SvGy^-1 with the outdoor and indoor occupancy factors of 0.2 and 0.8 respectively. The E_eff, was computed using equation (8)

[31]

, and the limit of 1mSv/y is considered acceptable for the general public

[4]

E_eff(uSvy^-1) = D (nGyh^-1) x 24h x 365.25 days x 0.2 x 0.7 Sv Gyy^-1x 10^-3(8)

3.8. Excess Lifetime Cancer Risk

The ELCR (Excess lifetime cancer risk) is another parameter which describes the effect of radiation exposure. The ELCR can be defined as the probability of developing stochastic effect at a lifetime due to low doses of ionizing radiation to human being over a given period

[4]

. The ELCR in this work was calculated using equation (9)

[36]

ELCR = E_effX DL X RF(9)

where: E_eff is the annual effective dose equivalent, DL represents the average duration of life (estimated to be 70 years) and RF is a risk factor (Sv^-1). The risk factor can be defined as the fatal cancer risk per Sievert. For stochastic effects, the value for RF = 0.05 Sv^-1 for public members

[4]

3.9. Dose Assessment

The radioactivity of fish obtained from the study was used to estimate the total annual effective committed dose (H_T) of the population in the study area. The total dose ingested through the consumption of fish can be calculated by summing the doses derived from each radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K). However, ⁴⁰K is an essential biological element distributed throughout the body and its concentration in human tissue are under metabolic (homeostatic) control. In estimating the total annual effective committed dose we used the annual fish consumption rate value that is 8.5 kg/y reported in 2020

[37, 38]

. Therefore, the total annual effective committed dose was computed using equation (10) adopted from ICRP (International Commission on Radiological Protection) report

[39]

H_{T, r}= ∑ (Uⁱx Cⁱ_r) x gT_r(10)

Where; i denotes the food group, Uⁱis the consumption rate per capital (kg/y), Cⁱ_rthe activity concentration of a radionuclides r of interest (Bq/kg), and gT_ris the dose conversion coefficient for the ingestion of radionuclide r (Sv/Bq) in tissue. This is given as ²²⁶Ra, ²³²Th, and ⁴⁰K, with conversion factors of 2.8 x 10^-7, 2.3 x 10^-7, and 6.2 x 10-9 in Sv / Bq respectively

[39]

4. Results and Discussion

4.1. Radioactivity Levels in Fish

The analysis of radionuclides concentrations in fish samples yielded the results presented in Table 3. These results shows that the activity concentrations of ⁴⁰K in almost all fish samples were higher than the world average value

[4]

. Meanwhile, the activity concentrations of ²²⁶Ra were lower than the world average values. Besides, it was observed that the activity concentrations of ²³²Th in all samples were BDL (below detection limit) of the gamma spectrometry system used for sample analysis. From the result it shows that the species with code F002, FT001 and FM 003 accumulate more ²²⁶Ra while species with code FT001 accumulate more ⁴⁰K. This may be due to the different feeding habits of these species, geographical location and conditions as well as solubility of ⁴⁰K in water

[4]

. This observation is supported by literature like a study by Khan et al.

[40]

, which reported that radionuclide accumulation rates in fishes are influenced by their feeding habits and geographical location conditions. Also from the result, it has shown that concentration of ⁴⁰K in fish samples was so high than the recommended value, but the computed total annual effective committed dose (Table 4) due to the consumption of fish was below the recommended limit

[39]

. This implies that consumers of fish from marine coastal areas are safe. Besides, it has been reported that the ⁴⁰K level in human body are not affected by variations in the environmental level, as result its radiation dose within the body remain constant

[4, 41]

Table 3. Activity Concentration of radionuclides (Bq/kg) in fish samples from coastal marine areas in Tanzania; values are expressed as mean ±SEM (p>0.05 and sample size n=12).

S/No.	Sample Code	Activity (Bq/kg) ²²⁶Ra	Activity (Bq/kg) ²³²Th	Activity (Bq/g) ⁴⁰K
1	F001	BDL	BDL	573.1 ± 72.3
2	F 002	4.6 ± 1.5	BDL	286.0 ± 30.3
3	F003	1.5 ± 0.8	BDL	353.3 ± 34.5
4	F 004	BDL	BDL	620.3 ± 78.8
5	FT 001	10.4 ± 2.4	BDL	693.6 ± 48.9
6	FT 002	BDL	BDL	574.2 ± 63.2
7	FT 003	BDL	BDL	438.4 ± 50.6
8	FT 004	BDL	BDL	492.6 ± 30.4
9	FM 001	BDL	BDL	460.6 ± 28.6
10	FM 002	BDL	BDL	543.3 ± 64.3
11	FM 003	3.0 ± 1.3	BDL	373.9 ± 39.1
12	FM 004	BDL	BDL	456.6 ± 50.1
	Min	1.5 ± 0.8		286.0 ± 30.3
	Max	10.4 ± 2.4		693.6 ± 48.9
	Mean ± SEM	4.9 ± 1.9	BDL	488.8 ± 34.1

BDL- Below Detection Limit

Table 4. Total Annual Effective Dose from 226Ra and 40K compared to recommended limits (mSv/y).

Radionuclides

Effective dose (mSv/y)

References

²²⁶Ra

0.0117

⁴⁰K

0.0258

Total

0.0375

This study

Recommended limits

[39]

The mean activity concentration of ⁴⁰K reported in this study was higher than the values reported in other parts of the world like Nigeria

[42]

, Libya

[43]

, Bangladesh

[44]

, Pakistan

[45]

, and Malaysia

[46]

. Figure 2 shows the comparison of radionuclides concentrations in fish observed in this study with the concentrations reported elsewhere as well as the recommended average values.

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Figure 2. Shows the comparison of radionuclides concentration in fish observed in the study area and parts of the world as well as recommended average value.

4.2. Radiological Risk Indices in Fish

Following the high concentrations of radionuclides in fish, it was important to compute the radiological risk indices associated with consumption of fish in the study area. The H_in and ELCR were determined as presented in Table 5. The average values of all these indices were observed to be below the values recommended by UNSCEAR

[4]

, as shown in Table 5. Hence, although some fish samples appeared to have high activity concentrations of ⁴⁰K, the computation of radiological risk indices and total annual effective committed dose (Table 4) revealed no significant health risks posed by consumption of fish from the marine coastal areas in Tanzania.

Table 5. Computed radiological risk indices due to consumption of fish in the study area; values are expressed as mean ± SEM (p>0.05 and sample size n=12).

S/No.

Sample code

H_in

ELCR X 10-6

F001

0.1

105.7

F 002

0.06

52.9

F003

0.08

67.9

F 004

0.1

114.5

FT 001

0.2

147.4

FT 002

0.1

106.1

FT 003

0.09

81.2

FT 004

0.1

90.7

FM 001

0.1

85.1

FM 002

0.1

100.5

FM 003

0.09

74.6

FM 004

0.09

Min

0.06

52.9

Max

0.2

147.4

Mean±SEM

0.1±0.01

92.6±7.1

Recommended mean values

[4]

290

4.3. Radioactivity Levels in Sediments

The activity concentration of natural radionuclides in sediments samples was computed and presented in Table 6. It was found that activity concentration of ⁴⁰K was higher than other radionuclides in the study area which may be influenced by organic enrichment in sediments as a result of the waste discharges draining by rivers from mainland or coastal activities like farming, industrial and domestic municipal waste. The result also shows that the samples collected upper stream of the rivers, E₆001, E₆004, E₇002, E₇003, E₁004, E₄001 and E₄004 have more activity concentration when compare with those sample collected downstream, midpoint and along the ocean in each river and sewage pipeline except sample E₇001 and SWPT 003. This may justify that the natural radionuclide are draining from farming places, industrial places, domestic waste discharge, mineral exploration activities, oil and fuel extraction in the mainland and coastal itself and not from Ocean activities.

Again from Table 6, it shows that the activity concentration of natural radionuclides of sample collected from port station and ferry station were higher than those from river estuaries and sewage pipeline. The samples collected from Tanga port station were containing more activity than other port stations and ferry stations except sample with code MP002 because there was a dredging excise which was undertaken and samples were collected there. The higher concentration observed in port stations and ferry stations may be due to the geological and morphological of the rock formation. This observation was supported from the literature by Ramli et al.

[47]

, and Yii et al.

[5]

. Also, it is reported that the radioactivity of ²²⁶Ra and ²³²Th is linked with heavy minerals, while that of ⁴⁰K is associated with clay minerals

[48]

Moreover, from Table 6 it was observed that the ratio of ²²⁶Ra/⁴⁰K, ²³²Th/⁴⁰K and ²²⁶Ra/²³²Th were comparable with recommended average by UNSCEAR

[10]

. The ratio of ²²⁶Ra and ²³²Th shows that there was disequilibria of radionuclides in the study area which may be caused by anthropogenic activities. This observation can be supported from the literature by Higgy

[49]

Table 6. Activity Concentration of radionuclides in the sediment samples from the coastal marine areas in Tanzania; values are expressed as mean ±SEM (sample size n= 37).

S/No.

Sample code

Activity Bq/Kg Ra-226

Activity in Bq/Kg Th-232

Activity in Bq/Kg K-40

Ra-226 / K-40

Th-232 / K-40

Ra- 226 / Th-232

E6 001

15.4±1.8

15.0 ± 1.9

568.3 ± 54.5

0.03

1.03

E6 002

9.3 ± 1.4

14.1 ± 1.6

285.4 ± 29.1

0.03

0.05

0.66

E6 003

3.7 ± 0.8

3.2 ± 0.9

370.2 ± 36.5

0.01

1.16

E6 004

7.6 ± 0.5

6.0 ± 0.7

643.8 ± 15.1

0.01

1.27

E6 005

3.6 ± 0.6

2.4 ± 0.5

180.4 ± 17.5

0.02

0.01

1.5

E7 001

11.6±1.7

10.3 ± 1.3

405.5 ± 41.0

0.03

1.13

E7 002

8.7 ± 1.2

10.2 ± 1.3

488.7 ± 48.9

0.02

0.85

E7 003

14.3±1.6

20.2 ± 2.0

372.5 ± 35.1

0.04

0.05

0.71

SWP 001

4.5 ± 0.8

< MDA

202.9 ± 19.1

0.02

SWP 002

7.8 ± 0.6

7.6 ± 0.7

100.5 ± 6.2

0.08

1.03

SWP 003

5.8 ± 0.9

6.2 ± 0.8

311.5 ± 30.0

0.02

0.94

SWP 004

4.2 ± 1.1

3.4 ± 1.0

399.1 ± 40.7

0.01

1.24

DP 001

7.2 ± 0.3

4.6 ± 0.3

177.3 ± 4.8

0.04

0.03

1.57

DP 002

7.5 ± 0.5

4.2 ± 0.6

195.9 ± 6.6

0.04

0.02

1.79

DP 003

12.6±1.0

14.7 ± 1.0

314.9 ± 13.4

0.04

0.05

0.86

E1 001

7.6 ± 0.4

< MDA

420.2 ± 11.4

0.02

E1 002

8.4 ± 0.5

< MDA

396.0 ± 10.2

0.02

E1 003

7.1 ±1.6

7.6 ± 1.2

467.6 ± 46.7

0.02

0.93

E1 004

17.0±2.0

25.8 ± 3.6

395.8 ± 39.8

0.04

0.07

0.66

SWPT01

9.6 ± 1.6

7.4 ± 1.2

63.0 ± 11.4

0.15

0.12

1.29

SWPT02

7.7 ±0.7

7.6 ± 0.4

92.1 ± 4.1

0.08

1.01

SWPT03

46.6±6.9

47.1 ± 5.5

312.9 ± 44.0

0.15

0.99

SWPT04

9.0 ± 0.4

< MDA

86.9 ± 3.0

0.1

SWPT05

11.8±1.1

7.4 ± 0.7

153.6 ± 12.1

0.08

0.05

1.59

TP 001

15.4±0.8

12.7 ± 0.8

324.2 ± 14.7

0.05

0.04

1.21

TP 002

32.1±0.7

19.5 ± 0.7

210.9 ± 5.1

0.15

0.09

1.65

TP 003

31.2±2.2

21.9 ± 1.4

238.1 ± 16.4

0.13

0.09

1.42

TP 004

28.6±3.1

23.1 ± 2.4

196.1 ± 21.4

0.15

0.12

1.24

TP 005

27.9±1.5

22.7 ± 1.1

267.5 ± 14.1

0.1

0.08

1.23

E4 001

16.0±1.2

25.5 ± 1.5

607.0 ± 28.7

0.03

0.04

0.63

E4 002

10.3±1.4

21.5 ± 2.3

560.8 ± 55.4

0.02

0.04

0.48

E4 003

6.9 ± 1.1

10.1 ± 1.2

524.0 ± 50.3

0.01

0.02

0.68

E4 004

16.3±1.9

41.1 ± 4.1

641.9 ± 62.2

0.03

0.06

0.39

MP 001

12.3±0.5

12.3 ± 0.9

285.2 ± 9.1

0.04

MP 002

64.7±3.0

(117.2 ± 5.4)

234.9 ± 11.2

0.28

MP 003

12.5±0.6

9.5 ± 0.6

281.2 ± 8.0

0.04

0.03

1.32

MP 004

17.3±2.3

20.9 ± 2.7

354.2 ± 36.4

0.05

0.06

0.83

Min.

3.6 ± 0.6

2.4 ± 0.5

63.0 ± 11.4

0.01

0.39

Max.

64.7±3.0

47.1 ± 5.5

643.8 ± 15.1

0.28

0.15

1.79

Mean±SEM

15.1±2.2

14.9 ±2.02

320.8±27.4

0.06±0

0.05±0

1.08±0.1

Recommended mean values

[10]

0.067

1.0

The result in the brackets () are outliers and excluded from average.

Figure 3 shows bar chart graph illustrating the distribution of mean activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the study area. It was observed that the mean activity concentration of ⁴⁰K in river estuaries (E₆, E₇, E₄, E₁) are so high compared to sewage pipelines and port/ferry site. The Tanga sewage pipeline (SWPT) contain the least mean activity concentration of ⁴⁰K. The other radionuclides ²²⁶Ra and ²³²Th at the TP, MP, E₄ and SWPT site contain a bit higher mean activity concentration compared to other sites.

Download: Download full-size image

Figure 3. The average activity concentration of 226Ra, 232Th and 40K in Bq/kg of the sediment sample for the locations under the study area.

Figure 4 and Figure 5 were plotted to test for correlation between ²³²Th and ²²⁶Ra and ⁴⁰K and ²²⁶Ra respectively. It is noted that a moderate to strong good correlation between ²³²Th and ²²⁶Ra was observed with correlation coefficient of 0.79 (r= 0.79, p< 0.0001), this indicate that the correlation is highly statistically significant and hence the two radionuclide are in the same origin. Also the correlation was observed between ²²⁶Ra and ⁴⁰K with correlation coefficient of -0.103 (r= -0.103, p≈ 0.545) which is very weak negative correlation that means no statistically significant correlation and suggest that no significant linear relationship between activity concentration of ⁴⁰K and ²²⁶Ra.

Download: Download full-size image

Figure 4. The correlation between activity concentrations of 232Th and 226R.

Download: Download full-size image

Figure 5. The correlation between activity concentrations of 40K and 226Ra.

Following the comparison between the ranges and mean activity concentration of radionuclide (²²⁶Ra, ²³²Th and ⁴⁰K) in sediments samples collected in coastal marine areas of Tanzania and some other countries of the world was presented in Table 7. The radioactivity levels in the coastal marine areas of Tanzania sediments was found to be higher than the levels reported for the Mediterranean coast of Egypt

[50]

, coastal structure in Kuwait

[51]

, coast of Oman sea, Iran

[52]

, Qatar

[53]

, and coast of Greater Accra, Ghana

[54]

, except ²²⁶Ra in Kuwait and ²³²Th in Ghana were higher compared to the current study. Also for Patras Harbour, Greece

[55]

, Mumbai Harbour, India

[56]

, Red Seashore sediment, Egypt

[57]

, Coastal Marine Sediments, Gulf of Oman

[58]

, Yangtze estuary, China

[59]

, Izmit Bay, Turkey

[60]

, and Malaysia Coast, South China sea

[61]

, the levels are comparable with the current study, except the radioactivity of ⁴⁰K in Greece, India, Egypt, Turkey and China is higher than the current study.

Moreover, from Table 7, when you compare the ranges, the radioactivity levels of the current study was found to be higher than the levels reported for Qatar

[53]

, and northern coast of Oman Sea, Iran

[52]

. The Yangtze Estuary, China

[59]

, was found to be comparable with the current study except the ranges of ²³²Th and ⁴⁰K was higher than the current study. Therefore, the mean and ranges of the radioactivity levels in sediment samples of the current study were lower than recommended values reported worldwide by UNSCEAR

[10]

, but mostly comparable with other part of the world. Hence the sediments collected from coastal marine areas of Tanzania cannot pose radiological effect to human being as well as biota animals.

Table 7. Comparison of average /ranges of Activity Concentration of 40K, 232Th and 226Ra (Bq/kg) from study area, other parts of the world and the recommended values.

S/No.

Location

Average/ranges of Activity Concentration in Bq/kg

Reference

Ra - 226

Th - 232

K - 40

Kuwait

227

[53]

Greece

22.6

24.5

497

[55]

India

10.6

436

[56]

Egypt

2.1

[50]

Ghana

22.04

108.6

29.78

[54]

Egypt

24.7

31.4

427.5

[57]

Iran

11.8 -22.7

10.7 - 25.0

223 - 535

[52]

Qatar

4.2 - 19.5

1.0 - 6.0

11 - 188

[53]

China

13.7 - 52

26.1 - 71.9

392 - 898

[59]

Turkey

0.0 - 18.0

568

[60]

Oman

0.0 - 16.2

0.0 - 34.5

54.7

[58]

Malaysia

27.7

73.3

[61]

World range

17.0 - 60.0

11.0 -64.0

140.0 - 850.0

[10]

World average

400

[10]

Tanzania, range

3.6 - 64.7

2.4 - 47.1

63.0 - 643.8

Current study

Tanzania, average

14.6

327.9

Current study

4.4. Radiological Risk Indices in Sediments

The radiological indices and hazard indices for sediments samples collected from study area were computed and presented in Table 8. Generally it observed that the radiological hazards indices were below the recommended values as reported by UNSCEAR

[4]

, as shown in Table 8.

Moreover, when you compare the current study with the reported study recorded in Table 8, it shows that the Suliman et al.

[57]

in Egypt and Al-Trabulsy et al.

[61]

in Saudi Arabia have higher values for Ra_eq and D compared with current study. At the same times Papeefthymiou et al.

[54]

in Ghana reported to have lower values for Ra_eqand E_effand Ramasamy et al.

[62]

in India reported to have lower value for ELCR compared to the current study.

Hence, in view the radiological hazard indices calculated in sediments samples and compared to the recommended values and other studies reported over the world it shows that the radioactivity levels in the coastal marine areas of Tanzania sediments have no radiological concern for human health and biotic environment. Therefore, the sediment around the study can be used for building materials or other various applications.

Table 8. Using Average Activity Concentration to Computed Raeq, Hex, D, Eeff, Iγ, AGDE and ELCR for Sediments Samples from present study and sediments from other parts of world as well the recommended value; values are expressed as mean± SEM (p<0.05 and sample size n=9).

S/No.

Sample code

Ra_eq Bq/kg

H_ex

D nGy/h

Eeff µSv/y

I_γ

AGDE µSv/y

ELCR x 10-6

Reference

0.1

31.9

0.4

164.9

111.7

63.5

0.2

31.5

38.6

0.5

193

135.1

SWP

33.4

0.1

16.9

20.7

0.3

105.6

72.5

37.9

0.1

18.6

22.8

0.3

107.5

79.8

57.6

0.2

29.1

35.7

0.5

182.1

124.9

SWPT

49.8

0.1

22.9

28.1

0.4

114.1

98.4

74.4

0.2

34.5

42.3

0.5

168.9

148.1

92.5

0.2

45.7

0.7

289.9

196

69.3

0.2

32.7

40.1

0.3

105.6

72.5

Min

33.4

0.1

16.9

20.7

0.1

55.1

32.6

Max

92.5

0.2

45.7

0.7

289.9

196

Mean±SEM

58.8±6.2

0.2±0

28.7±2.9

35.1±3.6

0.4±0

159.1±20.2

115.4±13.6

Mean values, others areas

Red Seashore, Egypt

101

[57]

Coast of Accra, Ghana

0.5

0.1

[54]

India

0.002

[62]

Saudi Arabia

92.9

0.1

45.6

0.3

[61]

Recommended value

370

300

290

[4]

5. Conclusion

The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K of fish and sediments samples along the coastal areas of Tanzania was determined using the gamma spectrometry. The mean activity concentrations of ²²⁶Ra in fish (4.9 ± 1.9 Bq kg⁻¹) and sediments (15.1 ± 2.2 Bq kg⁻¹), ²³²Th in fish was below detection limit (BDL) and sediments (14.9 ± 2.0 Bq kg⁻¹) were compared to the global averages of 35 Bq kg⁻¹, and 45 Bqkg^-1respectively. The ⁴⁰K in fish (488.8 ± 34.1 Bq kg⁻¹) and sediments (320.8 ± 27.4 Bq kg⁻¹) were compared to the global average value of 420 Bq kg⁻¹. The study also revealed that the computed annual effective committed dose was below the recommended limit by ICRP although the mean activity concentration of ⁴⁰K in fish samples was higher than the value recommended worldwide. Additionally, the current study also has shown that the radiological hazards indices computed for fish and sediments samples were below recommended values. Likewise, the study also has shown strong good correlation between ²²⁶Ra and ²³²Th, while a weak correlation was observed between ⁴⁰K and ²²⁶Ra as well as ²³²Th in sediments samples.

Therefore, this study may conclude that the level of radioactivity in fish consumed in this study areas does not pose a significant radiological risk to fish consumers as well as sediments if it will be used for any purpose. This study also will be used as baseline for coastal marine areas of Tanzania for radioactivity and the data may be used by regulatory bodies during enforcing radiation protection policies. Lastly, the study recommends that research should be extended to other species of fish and the areas left behind during sample collection and extend the methodology to include further radionuclides of interest to nuclear security and safeguards.

Abbreviations

UNSCEAR	United Nations Scientific Committee on the Effects of Atomic Radiation
DNA	Deoxyribonucleic Acid
TAEC	Tanzania Atomic Energy Commission
IAEA	International Atomic Energy Agency
HPGe	High - Purity Germanium
AGDE	Annual Gonadal Dose Equivalent
ELCR	Excess Lifetime Cancer Risk
ICRP	International Commission on Radiological
BDL	Below Detection Limit

Acknowledgments

The authors acknowledge the financial support from Tanzania Atomic Energy Commission (TAEC) and the valuable logistics support from University of Dar es Salaam, Department of Physics.

Author Contributions

Melchior Ludovick Mungubariki: Conceptualization, Data curation, Formal Analysis, Methodology, Resources, Validation, Visualization, Poject administration, Writing– original draft, Writing– review & editing

Mwingereza John Kumwenda: Supervision, Validation, Visualization, Writing – review & editing

Innocent Jimmy Lugendo: Methodology, Supervision, Validation, Visualization, Writing – review & editing

Conflicts of Interest

The authors declares that they have no conflicts of interest.

References

[1]	Lo, K. F. A., Gunasiri, C. W. D. Impact of coastal land use change on shoreline dynamics in Yunlin County, Taiwan. Environments, 2014, (1), 124 -136. https://doi.org/10.3390/ENVIRONMENTS1020124
[2]	Yi, L., Chen, J., Jin, Z., Quan, Y., Han, P., Guan, S., Jiang, X. Impacts of human activities on coastal ecological environment during the rapid urbanization process in Shenzhen, China. Ocean Coast. Manag. 2018, (154), 121 - 132. https://doi.org/10.1016/j.ocecoaman.2018.01.005
[3]	Al-Howiti, N. S., Othmen, Z. O. B., Othmane, A. B., Chaffai, A. H. Use of Tridacna maxima, a bivalve in the biomonitoring of the Saudi Arabian Red Sea coast. Mar. Pollut. Bull. 2020, ID 150, 11076. https://doi.org/10.1016/j.marpolbul.2019.110766
[4]	UNSCEAR. Sources, Effects and risks of Ionizing Radiation: Report to the General Assembly with Scientific Annexes A and B, 120 (2020) New York.
[5]	Yii, M. W., Zaharudin, A., Abdul-Kadir, I. Distribution of naturally occurring radionuclides activity concentration in East Malaysian marine sediment. Appl. Radiat. Isot., 2009, (67), 630-635. https://doi.org/10.10.16/j.apradiso.2008.11.019
[6]	El- Taher, A., Abdelhalim, M. A. K. Elemental analysis of limestone by instrumental neutron activation analysis. J. Radioanal. Nucl. Chem., 2014, (299), 1949 - 1953. https://doi.org/10.1007/s10967-014-2925-4
[7]	Kurnaz, A., and Ku, B. Determination of radioactivity levels and hazards of soil and sediment samples in Firtina Valley, Turkey. J. Appl. Radiat. Isotopes, 2007 (65), 1281-12 89. https://doi.org/10.1016/j.apradiso.2007.06.001
[8]	UNSCEAR. Sources and Effects of Ionizing Radiation: Sources (Vol. 1). New York, (2013), United Nations Publications.
[9]	Kam, E., Bozkurt, A. Environmental radioactivity measurements in Kastamonu region of northern Turkey. Applied Radiation and Isotopes, 2007, 65(4), 440- 444. https://doi.org/10.1016/j.apradiso.2006.11.005
[10]	UNSCEAR. Sources and Effects of Ionizing Radiation: Report Vol. 1 to the General Assembly, with scientific annexes, United Nations Sales Publication, United Nations, New York, 2008.
[11]	Ravanat, J. L., Breton, J., Douki, T., Gasparutto, D., Grand, A., Rachidi, W., Sauvaigo, S. Radiation-mediated formation of complex damage to DNA: a chemical aspect overview. Br. J. Radiol., 2014 (87), 20130715. https://doi.org/10.1259/bjr.20130715
[12]	ICRP. Radiological Protection from Naturally Occurring Radioactive Material (NORM) in industrial processes, vol. 48, SAGE publication Ltd, (2019). https://doi.org/10.1177/0146645319874589
[13]	Harb S. Natural radioactivity concentration and annual effective dose in selected vegetables and fruits. J. Nucl. Particle Phys., 2015, (5), 70 - 73. https://doi.org/10.5923/j.jnpp.20150503.04
[14]	Azouazi, M., Ouahidi, Y., Fakhi, S., Andres, Y., Abbe, J. C., Benmansour, M. Natural radioactivity in phosphates, phosphogypsum and natural waters in Morocco. J. Environ. Radioact. 2001, (54), 231-242. https://doi.org/10.1016/s0265-931x(00)00153-3
[15]	El-Gamal, A., Nasr, S., El-Taher, A. Study of the spatial distribution of natural radioactivity in the upper Egypt Nile River sediments. Radiat. Meas., 2007, (42), 457- 465. https://doi.org/10.1016/j.radmeas.2007.02.054
[16]	Radi Dar, M. A., El-Saharty, A. A. Some radioactive elements in the coastal sediments of the Mediterranean Sea. Radiat. Prot. Dosim., 2013, (153), 361-368. https://doi.org/10.1093/rpd/ncs104
[17]	Banzi, F. P., Kifanga, L. D., Bundala, F. M. Natural radioactivity and radiation exposure at Minjingu phosphate mine in Tanzania. Radiation Protection, 2000, (20), 41 - 51. https://doi.org/10.1088/0952-4746/20/1/305
[18]	Lolila, F. Establishment of baseline data of external ionizing radiation dose at proposed uranium mining sites and their neighbouring residential areas in Tanzania. Msc thesis. University of Dar es Salaam, Tanzania, November, 2011.
[19]	Mohammed, N. K., Mazunga, M. S. Natural radioactivity in soil and water from likuyu Village in the neighbourhood of Mkuju uranium deposit. International Journal of Analytical Chemistry, 2013, ID 501856. http://dx.doi.org/10.1155/2013/501856
[20]	Leonid L. Nkuba and Najat K. Mohammed. Determination of radioactivity in maize and mung beans grown in the neighbourhood of Minjingu phosphate mine, Tanzania. Tanz. J. Sci. 2014, (40). https://doi.org/10.65085/2507-7961.1817
[21]	Kazoka, A. R., Mwalilino, J., Mtoni, P. A radiological risk assessment of ²²⁶Ra, ²²⁸Ra and ⁴⁰K isotpes in Tilapia Fish and its granite environment in Singida Municipality, Tanzania. Earth 2023, 4 pp 540-551. https://doi.org/10.3390/earth4030028
[22]	URT. Tanzania in figures. National Bureau of Statistics, Ministry of Finance and Planning, Dodoma June, 2020.
[23]	URT. Investment guide on waste management in Tanzania. The United Republic of Tanzania. Dodoma: Vice Presidents’ office, March, 2020.
[24]	World Bank. Fertilizer consumption (kilogram per hectare of arable land) - Tanzania. https://worldbank.org/indicator/AG.CON.FERT.zs?end=2018 Accessed June 20, 2025.
[25]	NEMC. State of the Coast for Mainland Tanzania. National Environment Management Council (NEMC). Dodoma, Tanzania. 2014, Pp. xxxiv+293p.
[26]	Ravisankar, R., Chandranohan, J., Chandrasekaran, A., Jebakumar, J. P. P., Vijayalakshmi, I., Vijayagopal, P., Venkatraman, B. Assessment of radioactivity concentration of natural radionuclides and radiological hazards indices in sediments samples from the East Coast of Tamilnadu, India with statistical approach. Mar. Pollut. Bull. 2015, (97), 419-430. https://doi.org/10.1016/j.marpolbul.2015.05.058
[27]	IAEA. Measurement of radionuclides in food and the environment; IAEA Technical Report Series no. 295; International Atomic Energy Agency: Vienna, Austria, 1989.
[28]	ORTEC. ORTEC Gamma Vision® Maestro-PRO®. 2020.
[29]	El-Taher, A., Madkour, H. A. Environmental and radioecological studies on shallow marine sediments from harbour areas along the Red Sea coast of Egypt for identification of anthropogenic impacts. Isotopes in environmental and health studies, 2014, 50 (1), 120-133. https://doi.org/10.1080/10256016.2013.826211
[30]	Liu, X., Lin, W. Natural radioactivity in the beach sand and soil along the coastline of Guangxi Province, China. Mar. Pollut. Bull., 2018, (135), 446 - 450. https://doi.org/10.1016/j.marpolbul.2018.07.057
[31]	Akpanowo, M. A., Umaru, I., Iyakwari, S., Joshua, E. O., Yusuf, S., Ekong, G. B. Determination of natural radioactivity levels and radiological hazards in environmental samples from artisanal mining sites of Anka, North-West Nigeria. Scientific African, 10(2020) e00561. https://doi.org/10.1016/j.sciaf.2020.e00561
[32]	Ayeni D. A, Adebiyi F. M. Evaluation of natural radioactivity and radiation hazards of soils around petroleum products marketing company using gamma-ray spectrometry. Tanz. J. Sci. 2022. 48(2), pp. 304-312. https://doi.org/10.4314/tjs.v48i2.7
[33]	Darwish D. A. E, Abul-Nasr K. T. M, EL-Khayatt A. M. The assessment of natural radioactivity and its associated radiological hazards and dose parameters in granite samples from South Sinai, Egypt. Journal of Radiation Research & Applies Sciences. 2015, 8(1), pp. 17 - 25. https://doi.org/10.1016/j.jrras.2014.10.003
[34]	Yachiso G. T., Chaubey A. K., Turi B. Measurement of natural radionuclide levels and hazards in the Lega Dembi Gold mine, Oromia, Ethiopia. Isotopes in Environmental and Health Studies, 2023, 59(4-6), pp. 554-566. https://doi.org/10.21203/rs.3.rs-1854146/v1
[35]	Adebiyi F. M., Ore O. T., Adeola A. O., Durodola S. S., Akeremale O. F., Olubodun K. O., Akeremale O. K. Occurrence and remediation of naturally occurring radioactive materials in Nigeria: Areviw. Environmental Chemistry letters, 2021, 19(4), pp. 3243 - 3262. https://dio.org/10.1007/s10311-021-01237-4
[36]	Taskin H., Karavus M., Ay P., Topuzoglu A., Hidiroglus S., Karahan G. Radionuclide concentration in soil and lifetime cancer risk due to gamma radioactivity in Kirlareli, Turkey. Journal of Environmental Radioactivity, 2009, 100(1), pp. 49- 53. https://doi.org/10.1016/j.jenvral.2008.10012
[37]	FAO. The state of World Fisheries and Aquaculture 2020. Sustainability in Action. Rome, 2020. https://doi.org/10.4060/ca9229en
[38]	Peart, J., Tran N., Chan, C. Y., Maskaeva, A., Shoko, A. P., Kimirei, I. A., Madalla, N. A. A review of fish supply-demand in Tanzania. Penang, Malaysia: World Fish, 2021. Program Report: 2021-2032. https://doi.org/10.13140/RG.2.2.17013.65760
[39]	ICRP. Annals of the ICRP; ICRP Publication 103: Boston, MA, USA, 2007.
[40]	Khan, M. F., Raj, Y. L., Ross, E. M., Wesley, S. G. Concentration of natural (⁴⁰K, ²²⁸Ra and ²²⁶Ra) in seafood and their dose to coastal adult inhabitants around Kudankulam, Gulf of Mannar, South India. Int. J. Low Radiation, 2007, 4 (3), 217-231. https://doi.org/10.1504/ijlr.2007.015818
[41]	Shanthi G, Maniyan C. G, Allan G, Gnana R, Thampi T. J. Radioactivity in food crops from high background radiation area in Southwest India. Curr. Sci. 2009, 97(9): 1331- 1335.
[42]	Adamu, R., Zakari, Y. I., Ahmed, A. Y., Abubakar, S., Vatsa, A. M. Analysis of Activity Concentration due to Natural Radionuclides in the Fish of Kainji Lake. Advances in Applied Science Research, 2013, 4 (4), 283 - 287.
[43]	Hamad, R., Ikraiam, F., Hasan, H. Determination of specific natural radionuclides in the bones of some local fish commonly consumed from the Eastern Libyan Coast. J. Rad. Nucl. Appl., 2023, 8(30), 283-289. https://doi.org/10.18576/jrna/080310
[44]	Ghose, S., Alam, M. N., Islam, M. N. Radiation dose estimation from the analysis of radionuclides in marine fish of the Bay of Bengal. Radiat. Prot. Dosim., 2000, 87, 287-291. https://doi.org/10.1093/oxfordjournals.rpd.a33010
[45]	Tahir, S. N. A., Alaamer, A. S., Ayub, M., Khan, M. Z. Radiometric analysis of samples of domestic fish species and radiological implications. Health Physics, 2010, 98(5), 7 41-744. https://doi.org/10.1097/hp.0b013e3181d18f4a
[46]	Khandaker, M. U., Olatunji, M. A., Shuib, K. S. K., Hakimi, N. A., Nasir, N. L. M., Asaduzzaman, K. Y. M., Amin, Y. M., Kassim, H. A. Natural radioactivity and effective dose due to the bottom sea and estuaries marine animals in the coastal waters around Peninsular Malaysia. Radiation Protection Dosimetry, 2015, 167(1-3), 196-200. https://dio.org/10.1093/rpd/ncv243
[47]	Ramli, A. T., Abdel-Wahab, M. A., Lee, M. H. Geological influence on terrestrial gamma ray dose rate in the Malaysian state of Johore. Appl. Radiat. Isot. 2000, 54, 327 - 333. https://doi.org/10.1016/s0969-8043(00)00103-2
[48]	Nyarko, E., Botwe, B., Ansong, J., Delfanti, R., Barsanti, M., Schirone, A., Delbono, L. Determination of ²¹⁰Pb, ²²⁶Ra and ¹³⁷Cs in beach sands along the coastline of Ghana. African Journal of Environmental Pollution and Health, 2011, 9, 17-23.
[49]	Higgy, R. H. Natural radionuclides and plutonium isotopes in soil and shore sediments on Alexandria Mediterranean Sea coast of Egypt. Radiochim Acta, 2000, 88, 47-54. https://doi.org/10.1524/ract.2000.88.1.047
[50]	Saad, H. R., Al-Azmi, D. Radioactivity concentrations in sediments and their correlation to the coastal structure in Kuwait. Applied Radiation and Isotopes, 2002, 56, 991 - 997. https://dx.doi.org/10.1016/s0969-8043(02)00061-1
[51]	Zare, M. R., Mostajaboddavati, M., Kamali, M., Abdi, M. R., Mortazavi, M. S. ²³⁵U, ²³⁸U, ²³²Th, ⁴⁰K and ¹³⁷Cs activity concentrations in marine sediments along the northern coast of Oman Sea using high-resolution gamma-ray spectrometry. Mar. Pollut. Bull., 2012, 64, 1956-1961. https://doi.org/10.1016/j.marpolbul.2012.05.005
[52]	Al-Qaradawi, I., Abdel-Moati, M., Al-Yafei, M. A. A., Al-Ansari E., Al-Maslamani, I., Holm E., Al-Shaikh, I., Mauring, A., Pinto, P. V., Abdulmalik, D., Amir, A., Miller, M., Yigiterhan, O., Person, B. Radioactivity levels in the marine environment along the Exclusive Economic Zone (EEZ) of Qatar. Mar. Pollut. Bull., 2015, 90, 323-329. http://dx.org/10.1016/j.marpolbul.2014.10.021
[53]	Amekudzie, A., Emi-Reynolds, G., Faanu, A., Darko, E. O., Awudu, A. R., Adukpo, O., Quaye, L. A. N., Kpordzro, R., Agvemang, B., Ibrahim, A. Natural radioactivity concentrations and dose assessment in shore sediments along the coast of Greater Accra, Ghana. World Applied Sciences Journal, 2011, 13(11), 2338 - 2343.
[54]	Papaefthymiou, H., Papatheodorou, G., Moustakli, A., Christodoulou, D., Geraga, M. Natural radionuclides and ¹³⁷Cs distributions and their relationship with sedimentological processes in Patras Harbour, Greece. Journal of Environmental Radioactivity, 2007, 94(2), 55 - 74. https:doi.org/10.1016/j.jenvrad.2006.12.014
[55]	Sugandhi S, Joshi V. M, Ravi P. Studies on natural and anthropogenic radionuclides in sediment and biota of Mumbai Harbour Bay. Journal of Radioanalytical and Nuclear Chemistry, 2014, 300(1): 67 - 70. https://doi.org/10.1007/s10967-014-2944-1
[56]	El-Mamoney, M. H., Khater, A. E. M. Environmental characterization and radioecological impacts of non-nuclear industries on the Red Sea coast. Journal of Environmental Radioactivity, 2004, 73 (2), 151-168. https://doi.org/10.1016/j.jenvrad.2003.08.008
[57]	Suliman, I. I., Alsafi, K. Radiological risk to human and non-human Biota due to radioactivity in Coastal sand and marine sediments, Gulf of Oman. Life, 2021, 11, 549. https://doi.org/10.3390/life11060549
[58]	Wang, J., Du, J., Bi, Q. Natural radioactivity assessment of surface sediments in the Yangtze Estuary. Mar. Pollut. Bull., 2017 (114), 602-608. https://doi.org/10.1016/j.marpolbul.2016.09.040
[59]	Ergul, H. A., Belivermis, M., Kilic, O., Topcuoglus, S., Cotuk, Y. Natural and Artificial radionuclide activity concentrations in surface sediments of Izmit Bay, Turkey. Journal of Environmental Radioactivity, 2013, (126), 125-132. https://doi.org/10.1016/j.jenvrad.2013.07.015
[60]	Mohamed, C. A. R., Mahmood, Z. U. W., Ahmad, Z., Ishak, A. K. Enrichment of natural radium isotopes in the southern South China Sea surface sediments. Coastal Marine Science, 2010, 34(1), 165 - 171.
[61]	Al-Trabulsy, H. A., Khater, A. E. M., Habbani, F. I. Radioactivity levels and radiological hazard indices at the Saudi coastline of the Gulf of Aqaba. Radiat. Phys. Chem., 2011, 80 (3), 343-348. https://doi.org/10.1016/j.radphyschem.2010.09.002
[62]	Ramasamy, V., Suresh, G., Meenakshisundaram, V., Gajendran, V. Evaluation of natural radionuclide content in river sediments and excess lifetime cancer risk due to gamma radioactivity. Research Journal of Environmental and Earth Sciences, 2009, 1(1), 6 - 10.

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Mungubariki, M. L., Kumwenda, M. J., Lugendo, I. J. (2026). Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania. Advances in Applied Sciences, 11(3), 121-138. https://doi.org/10.11648/j.aas.20261103.18

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Mungubariki, M. L.; Kumwenda, M. J.; Lugendo, I. J. Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania. Adv. Appl. Sci. 2026, 11(3), 121-138. doi: 10.11648/j.aas.20261103.18

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Mungubariki ML, Kumwenda MJ, Lugendo IJ. Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania. Adv Appl Sci. 2026;11(3):121-138. doi: 10.11648/j.aas.20261103.18

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@article{10.11648/j.aas.20261103.18,
  author = {Melchior Ludovick Mungubariki and Mwingereza John Kumwenda and Innocent Jimmy Lugendo},
  title = {Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania},
  journal = {Advances in Applied Sciences},
  volume = {11},
  number = {3},
  pages = {121-138},
  doi = {10.11648/j.aas.20261103.18},
  url = {https://doi.org/10.11648/j.aas.20261103.18},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.aas.20261103.18},
  abstract = {Environmental radioactivity monitoring is essential for assessing potential exposure risks to humans and marine ecosystem, particularly in coastal marine areas where anthropogenic and natural radionuclides may accumulate. However, research studies on natural radioactivity in Tanzania's coastal marine areas remain scarce. This study was therefore conducted to assess the radioactivity levels of natural radionuclides (226Ra, 232Th, and 40K) in marine sediments and fish samples from the Tanzanian coastal areas, and to estimate the associated radiological health hazards for both humans and marine ecosystem. A total of 49 samples comprising both sediment and fish were randomly collected from 12 coastal sites and composited for analysis. Radioactivity concentrations were measured using gamma spectrometry. For fish samples, the mean activity concentrations were 4.9 ± 1.9 Bq kg⁻1 dry weight (dw) for 226Ra, 488.8 ± 34.1 Bq kg⁻1 dw for 40K, while 232Th was below the detection limit. In sediments, the corresponding mean values were 15.1 ± 2.2, 14.9 ± 2.0, and 320.8 ± 27.4 Bq kg⁻1 dw for 226Ra, 232Th, and 40K, respectively. Based on these data, a comprehensive set of radiological hazard indices was computed, including radium equivalent activity (Raₑq), absorbed dose rate (D), annual effective dose equivalent (Eₑff), external and internal hazard indices (Hₑₓ and Hᵢₙ), representative gamma index (Iᵧ), annual gonadal dose equivalent (AGDE), excess lifetime cancer risk (ELCR), and annual effective dose (AED). The results showed that the computed total annual effective committed dose for fish consumption was below the 1 mSv y⁻1 as recommended by the ICRP, although the mean 40K activity in fish exceeded the global average of 420 Bq kg⁻1. All evaluated hazard indices (Raeq, Hex, D, Eeff, Iγ, AGDE, and ELCR) for sediments, as well as Hᵢₙ and ELCR for fish, were within permissible levels values. In conclusion, the current radioactivity levels in the studied coastal area do not pose a significant radiological risk to human health or the marine ecosystem. Nevertheless, it is advisable to keep monitoring for purpose of detecting any future changes due to natural or anthropogenic influences.},
 year = {2026}
}

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TY  - JOUR
T1  - Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania
AU  - Melchior Ludovick Mungubariki
AU  - Mwingereza John Kumwenda
AU  - Innocent Jimmy Lugendo
Y1  - 2026/08/18
PY  - 2026
N1  - https://doi.org/10.11648/j.aas.20261103.18
DO  - 10.11648/j.aas.20261103.18
T2  - Advances in Applied Sciences
JF  - Advances in Applied Sciences
JO  - Advances in Applied Sciences
SP  - 121
EP  - 138
PB  - Science Publishing Group
SN  - 2575-1514
UR  - https://doi.org/10.11648/j.aas.20261103.18
AB  - Environmental radioactivity monitoring is essential for assessing potential exposure risks to humans and marine ecosystem, particularly in coastal marine areas where anthropogenic and natural radionuclides may accumulate. However, research studies on natural radioactivity in Tanzania's coastal marine areas remain scarce. This study was therefore conducted to assess the radioactivity levels of natural radionuclides (226Ra, 232Th, and 40K) in marine sediments and fish samples from the Tanzanian coastal areas, and to estimate the associated radiological health hazards for both humans and marine ecosystem. A total of 49 samples comprising both sediment and fish were randomly collected from 12 coastal sites and composited for analysis. Radioactivity concentrations were measured using gamma spectrometry. For fish samples, the mean activity concentrations were 4.9 ± 1.9 Bq kg⁻1 dry weight (dw) for 226Ra, 488.8 ± 34.1 Bq kg⁻1 dw for 40K, while 232Th was below the detection limit. In sediments, the corresponding mean values were 15.1 ± 2.2, 14.9 ± 2.0, and 320.8 ± 27.4 Bq kg⁻1 dw for 226Ra, 232Th, and 40K, respectively. Based on these data, a comprehensive set of radiological hazard indices was computed, including radium equivalent activity (Raₑq), absorbed dose rate (D), annual effective dose equivalent (Eₑff), external and internal hazard indices (Hₑₓ and Hᵢₙ), representative gamma index (Iᵧ), annual gonadal dose equivalent (AGDE), excess lifetime cancer risk (ELCR), and annual effective dose (AED). The results showed that the computed total annual effective committed dose for fish consumption was below the 1 mSv y⁻1 as recommended by the ICRP, although the mean 40K activity in fish exceeded the global average of 420 Bq kg⁻1. All evaluated hazard indices (Raeq, Hex, D, Eeff, Iγ, AGDE, and ELCR) for sediments, as well as Hᵢₙ and ELCR for fish, were within permissible levels values. In conclusion, the current radioactivity levels in the studied coastal area do not pose a significant radiological risk to human health or the marine ecosystem. Nevertheless, it is advisable to keep monitoring for purpose of detecting any future changes due to natural or anthropogenic influences.
VL  - 11
IS  - 3
ER  -

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Author Information

Melchior Ludovick Mungubariki

Department of Physics, University of Dar es Salaam, Dar es Salaam, Tanzania; Radiation Control Directorate, Tanzania Atomic Energy Commission, Arusha, Tanzania

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http://orcid.org/0009-0006-7239-1655
Mwingereza John Kumwenda

Department of Physics, University of Dar es Salaam, Dar es Salaam, Tanzania

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http://orcid.org/0000-0003-1752-4807
Innocent Jimmy Lugendo

Department of Physics, University of Dar es Salaam, Dar es Salaam, Tanzania

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http://orcid.org/0000-0002-7260-2356

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Mungubariki, M. L., Kumwenda, M. J., Lugendo, I. J. (2026). Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania. Advances in Applied Sciences, 11(3), 121-138. https://doi.org/10.11648/j.aas.20261103.18

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ACS Style

Mungubariki, M. L.; Kumwenda, M. J.; Lugendo, I. J. Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania. Adv. Appl. Sci. 2026, 11(3), 121-138. doi: 10.11648/j.aas.20261103.18

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AMA Style

Mungubariki ML, Kumwenda MJ, Lugendo IJ. Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania. Adv Appl Sci. 2026;11(3):121-138. doi: 10.11648/j.aas.20261103.18

Copy | Download

@article{10.11648/j.aas.20261103.18,
  author = {Melchior Ludovick Mungubariki and Mwingereza John Kumwenda and Innocent Jimmy Lugendo},
  title = {Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania},
  journal = {Advances in Applied Sciences},
  volume = {11},
  number = {3},
  pages = {121-138},
  doi = {10.11648/j.aas.20261103.18},
  url = {https://doi.org/10.11648/j.aas.20261103.18},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.aas.20261103.18},
  abstract = {Environmental radioactivity monitoring is essential for assessing potential exposure risks to humans and marine ecosystem, particularly in coastal marine areas where anthropogenic and natural radionuclides may accumulate. However, research studies on natural radioactivity in Tanzania's coastal marine areas remain scarce. This study was therefore conducted to assess the radioactivity levels of natural radionuclides (226Ra, 232Th, and 40K) in marine sediments and fish samples from the Tanzanian coastal areas, and to estimate the associated radiological health hazards for both humans and marine ecosystem. A total of 49 samples comprising both sediment and fish were randomly collected from 12 coastal sites and composited for analysis. Radioactivity concentrations were measured using gamma spectrometry. For fish samples, the mean activity concentrations were 4.9 ± 1.9 Bq kg⁻1 dry weight (dw) for 226Ra, 488.8 ± 34.1 Bq kg⁻1 dw for 40K, while 232Th was below the detection limit. In sediments, the corresponding mean values were 15.1 ± 2.2, 14.9 ± 2.0, and 320.8 ± 27.4 Bq kg⁻1 dw for 226Ra, 232Th, and 40K, respectively. Based on these data, a comprehensive set of radiological hazard indices was computed, including radium equivalent activity (Raₑq), absorbed dose rate (D), annual effective dose equivalent (Eₑff), external and internal hazard indices (Hₑₓ and Hᵢₙ), representative gamma index (Iᵧ), annual gonadal dose equivalent (AGDE), excess lifetime cancer risk (ELCR), and annual effective dose (AED). The results showed that the computed total annual effective committed dose for fish consumption was below the 1 mSv y⁻1 as recommended by the ICRP, although the mean 40K activity in fish exceeded the global average of 420 Bq kg⁻1. All evaluated hazard indices (Raeq, Hex, D, Eeff, Iγ, AGDE, and ELCR) for sediments, as well as Hᵢₙ and ELCR for fish, were within permissible levels values. In conclusion, the current radioactivity levels in the studied coastal area do not pose a significant radiological risk to human health or the marine ecosystem. Nevertheless, it is advisable to keep monitoring for purpose of detecting any future changes due to natural or anthropogenic influences.},
 year = {2026}
}

Copy | Download

TY  - JOUR
T1  - Assessment of Radioactivity Levels and Radiological Hazards Indices in Sediments and Fish from Coastal Marine Areas of Tanzania
AU  - Melchior Ludovick Mungubariki
AU  - Mwingereza John Kumwenda
AU  - Innocent Jimmy Lugendo
Y1  - 2026/08/18
PY  - 2026
N1  - https://doi.org/10.11648/j.aas.20261103.18
DO  - 10.11648/j.aas.20261103.18
T2  - Advances in Applied Sciences
JF  - Advances in Applied Sciences
JO  - Advances in Applied Sciences
SP  - 121
EP  - 138
PB  - Science Publishing Group
SN  - 2575-1514
UR  - https://doi.org/10.11648/j.aas.20261103.18
AB  - Environmental radioactivity monitoring is essential for assessing potential exposure risks to humans and marine ecosystem, particularly in coastal marine areas where anthropogenic and natural radionuclides may accumulate. However, research studies on natural radioactivity in Tanzania's coastal marine areas remain scarce. This study was therefore conducted to assess the radioactivity levels of natural radionuclides (226Ra, 232Th, and 40K) in marine sediments and fish samples from the Tanzanian coastal areas, and to estimate the associated radiological health hazards for both humans and marine ecosystem. A total of 49 samples comprising both sediment and fish were randomly collected from 12 coastal sites and composited for analysis. Radioactivity concentrations were measured using gamma spectrometry. For fish samples, the mean activity concentrations were 4.9 ± 1.9 Bq kg⁻1 dry weight (dw) for 226Ra, 488.8 ± 34.1 Bq kg⁻1 dw for 40K, while 232Th was below the detection limit. In sediments, the corresponding mean values were 15.1 ± 2.2, 14.9 ± 2.0, and 320.8 ± 27.4 Bq kg⁻1 dw for 226Ra, 232Th, and 40K, respectively. Based on these data, a comprehensive set of radiological hazard indices was computed, including radium equivalent activity (Raₑq), absorbed dose rate (D), annual effective dose equivalent (Eₑff), external and internal hazard indices (Hₑₓ and Hᵢₙ), representative gamma index (Iᵧ), annual gonadal dose equivalent (AGDE), excess lifetime cancer risk (ELCR), and annual effective dose (AED). The results showed that the computed total annual effective committed dose for fish consumption was below the 1 mSv y⁻1 as recommended by the ICRP, although the mean 40K activity in fish exceeded the global average of 420 Bq kg⁻1. All evaluated hazard indices (Raeq, Hex, D, Eeff, Iγ, AGDE, and ELCR) for sediments, as well as Hᵢₙ and ELCR for fish, were within permissible levels values. In conclusion, the current radioactivity levels in the studied coastal area do not pose a significant radiological risk to human health or the marine ecosystem. Nevertheless, it is advisable to keep monitoring for purpose of detecting any future changes due to natural or anthropogenic influences.
VL  - 11
IS  - 3
ER  -

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