Deposited Rates of Radionuclides

Abstract

• Temporal and Spatial Distribution of Radionuclides in Dust Fallout.

• The depositional fluxes of the natural radionuclides (⁴⁰K, ²¹⁰Pb, and ⁷Be) and the man-made radionuclides (¹³⁷Cs) have been calculated using efficiency calibrated ultra-low background gamma spectrometry in nine sampling sites covering Kuwait.

• Maps showing high and low concentrations of radionuclides distribution among Kuwait.

Radionuclides

Methodology

Temporal and Spatial Distribution of Radionuclides in Dust Fallout

The depositional fluxes of the natural radionuclides (⁴⁰K, ²¹⁰Pb, and ⁷Be) and the man-made radionuclides (¹³⁷Cs) were calculated using efficiency-calibrated ultralow background gamma spectrometry in nine sampling sites covering Kuwait (Fig. 6.1). The dust fallout samples were collected on a monthly basis. Four collectors were installed in each sampling location to collect the adequate sample mass required for radioactivity analysis. The composite samples were subjected to long counting times regarding attaining an acceptable detection limit and to resolve very low-intensity peaks.

The collected gamma spectra were analyzed by Genie-2000 (Canberra Inc, USA) using the spectral lines of the most intense gamma energy lines. The decay correction and building-up factor of ⁷Be during the sampling period (almost 30 days) were considered due to the relatively short half life of ⁷Be. The concentration of radionuclides in dry deposition fluxes (Bq m⁻²) per month was determined by multiplying their specific activities in Bq g⁻¹ with the weight per unit area of the collector (g m⁻²) during sampling time (30 days).

The variety of all of the calculated radionuclides and depositional fluxes revealed a temporal tendency (i.e., highest in the spring months [February, March, April], when the precipitation rates are highest, and hence, more dust is washed out and the lowest in October–November of each year) (Fig. 6.2). The correlation of depositional dust fallout and the radionuclides fluxes was in the order of ⁴⁰K; ¹³⁷Cs ;  ²¹⁰Pb  and ⁷Be. The strongest correlation was with the terrestrial origin ⁴⁰K (0.92), and the weakest was with the cosmogenic origin ⁷Be (0.67).

On the other hand, the spatial distributions of radionuclide depositional fluxes showed a site-dependent relationship that is similar to the spatial dust fallout: highest in the interior areas and gradually decreasing along the coastal line. Nevertheless, an exception of the cosmogenic radionuclide ⁷Be distribution was observed in some months because of possibly different climatologically conditions.

The averages of the depositional fluxes of similar months were gridded using the GIS (ArcGIS) software package and presented as averages on a monthly basis from October 2009 to August 2011.

• 1. Monthly spatial distribution of ⁷Be

Figures 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 6.11, 6.12, 6.13, 6.14 and 6.15 show the annual and monthly spatial deposition rates of the ⁷Be radionuclide in dust fallout during October 2009–October 2011. The minimum monthly deposition fluxes (2.4 Bq m⁻²) were observed in December, when the precipitation was the lowest. In contrast, the high concentration during the spring season (March–April–May) was due to rainfall during the period supporting the theory of wet precipitation commonly associated with the mixing of stratospheric and tropospheric air masses (Daish et al. 2005). In spring time, a rapid removal from lower polar troposphere to the troposphere at the northern hemisphere is well known (UNSCEAR 2000) and, possibly due to the folding of the troposphere during April and May at mid-latitude (30–50), enhances the removal of the stratospheric ⁷Be into the troposphere (Viezee and Singh 1980; Kritz et al. 1991). However, in contrast, the spatial distribution in the fall months (September–October–November) might be due to the effect of southeasterly wind contribution. The highest monthly readings (76.5 and 184 Bq m⁻²) were observed in January and April, respectively, due to the effect of a washout by precipitation.

• 2. Temporal, spatial distribution of ¹³⁷Cs

¹³⁷Cs is a human-made radionuclide with a half life of 30 years. It was produced during the atmospheric testing of thermonuclear weapons in the period extending from the mid-1950s to the 1980s. Global fallout of ¹³⁷Cs began in 1954, peaked in the early 1960s and subsequently decreased, reaching near-zero levels in the mid-1980s. Fallout levels were globally variable, reflecting both annual precipitation amount and location relative to the main weapons tests (Walling 2002). Smaller amounts of ¹³⁷Cs have been released into the atmosphere by catastrophes at nuclear power plants, notably the Chernobyl disaster in 1986, which resulted in additional outputs of ¹³⁷Cs fallout over large areas of Europe and adjacent regions. However, wide measurements of ¹³⁷Cs concentration have also been carried out in Kuwaiti aerosol, in cooperation with the Comprehensive Nuclear Test Ban Treaty (CTBT) from 1995 to 1999. The reported ¹³⁷Cs concentration in the air was between 1.44 and 107.84, with an average value of 10.6 μBq m⁻³ (Biegalski et al. 2001).

Figures 6.16, 6.17, 6.18, 6.19, 6.20, 6.21, 6.22, 6.23, 6.24, 6.25, 6.26, 6.27 and 6.28 illustrate the annual and monthly spatial deposition rates of ¹³⁷Cs, which display similar behavior to ²¹⁰Pb and ⁷Be variations. The correlation coefficients of ¹³⁷Cs/²¹⁰Pb and ¹³⁷Cs/⁷Be were 0.87 and 0.94, respectively. The average monthly deposition rates varied from 0.02 to 4.18 Bq m⁻², while the annual deposition rates varied from 0.2 to 50.21 Bq m⁻². Based on the previous observations (e.g., the influence of precipitation, wind direction, and depositional dust rates), the dominant source of ¹³⁷Cs fallout is the transportation of dust by the northwesterly wind, as the areas of northern Europe and eastern Mediterranean are most affected by ¹³⁷Cs fallout (nuclear bomb tests and Chernobyl accident), more so than the Gulf Region.

• 3. Temporal, spatial distribution of⁴⁰K

Figures 6.29, 6.30, 6.31, 6.32, 6.33, 6.34, 6.35, 6.36, 6.37, 6.38, 6.39, 6.40 and 6.41 illustrate the annual and monthly spatial deposition rates of ⁴⁰K radionuclide in dust fallout. The highest ⁴⁰K concentrations were observed in spring months, when it reached a maximum in March 2011 (96.27 Bq m⁻²) and the lowest in fall (1.8 Bq m⁻²), which is quite consistent with the dust loadings of the corresponding months. The annual variations of ⁴⁰K concentration in dust fallout varied from 74 to 557 Bq m⁻², as presented in Fig. 6.29. This quantity of the ⁴⁰K deposition rate corresponds to about 412 Bq kg⁻¹ and the average measured ⁴⁰K concentration in Kuwaiti soil is 365 Bq kg⁻¹, which is similar to the worldwide average concentration (420 Bq kg⁻¹⁾ (UNSCEAR 2000). The distribution of ⁴⁰K monthly and seasonal variations displays similar behavior to the dust fallout trend. However, the site specificity of ⁴⁰K is very similar to the dust deposition distribution, which is very low in the coastal zone, significantly increasing in the southwest of the country.

• 4. Temporal, spatial distribution of ²¹⁰Pb

Figures 6.42, 6.43, 6.44, 6.45, 6.46, 6.47, 6.48, 6.49, 6.50, 6.51, 6.52, 6.53 and 6.54 illustrate the annual and monthly spatial deposition rates of ²¹⁰Pb radionuclide in dust fallout from October 2009 to October 2011. The highest ²¹⁰Pb concentrations were observed in spring (41.4 Bq m⁻²) and the lowest in fall (1.8 Bq m⁻²), which is quite consistent with the dust loadings of the corresponding months. However, the wet precipitation associated with Sarrayat and Koss played a major role in obtaining these high deposition fluxes (Aba et al. 2016, 2018; Al-Dousari et al. 2016). The monthly deposition ratios of ⁷Be and ²¹⁰Pb are largely consistent with the dust loading in the corresponding months. However, an extreme deposition rate (63 Bq m⁻²) was observed in March 2011, when an exotic storm hit Kuwait .

Samples Locations

Figure 6.1.

Fig. 6.1

Sampling locations of dust fallout and digital elevation model of Kuwait using ASTER stereo data

Temporal Variations of Radionuclides

Figure 6.2.

Fig. 6.2

Temporal variations of radionuclide depositional fluxes in Kuwait

Annual Deposited Rates of ⁷Be

The average annual ⁷Be deposited rates in Kuwait from October 2009 to August 2011 varied from 339 to 481 Bq m⁻², with an average similar (422 Bq m⁻²) to the reported data of the global model (400 Bq m⁻²). The maximum rates were found in a transect width of about 50 km from north to south. The minimum rates were shown along the transect from the middle of the country down to the southeastern part. The dominant annual wind direction is northwesterly (Fig. 6.3).

Fig. 6.3

Average deposited rates of ⁷Be

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Ratqah Dibdibah Um Al Madafi’ Liyah	Sulaybiyah Wafra Farms KhurFawaris Khiran Qurain

Monthly Deposited Rates of ⁷Be

The monthly ⁷Be deposited rates in Kuwait January 2010–2011 reveal a range from 13.6 to 76.5 Bq m⁻², with the maximum in northern areas and the lowest in southern areas. The predominant wind direction for this month was northwesterly (Fig. 6.4).

Fig. 6.4

Average deposited rates of ⁷Be in January (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Ratqah Um Eish Raudhatain Huwaymilyah	Salmi Sulaybiyah Wafra Farms KhurFawaris Khiran

The monthly rates at which ⁷Be were deposited in Kuwait in February 2010–2011 which reveal a range from 36.08 to 63.83 Bq m⁻², with three maximum spots. This possibly happened because of the effect of dust storms this month. The predominant wind direction for this month was northwesterly (Fig. 6.5).

Fig. 6.5

Average deposited rates of ⁷Be in February (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Bubiyan Bridge Dibdibah Wafra Farms KhurFawaris Subiyah	Salmi Um Al Madafi’ Liyah Shegaya Um Eish

The monthly ⁷Be deposited rates in Kuwait during March 2010–2011 reveal a range from 28.63 to 57.54 Bq m⁻², with a maximum in the central region with the northern, western wind corridor, and the lowest in the northern area. The predominant wind direction for this month was northwesterly, with high speeds sometimes. However, the occurrence of dust storms was lower in February, as well as precipitation. Nevertheless, the effect of the exotic storm that hit Kuwait in March 2011 led to critical dynamic weather that could probably have decreased the ⁷Be deposition flux (Fig. 6.6).

Fig. 6.6

Average deposited rates of ⁷Be in March (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Atraf Um Al Madafi’ Liyah Sulaybiyah Kabd	Abdulli Salmi Subiyah Shegaya Ratqah

The monthly ⁷Be deposited rates in Kuwait during April 2010–2011 reveal the highest deposited rates, with a range from 106 to 184 Bq m⁻², with a maximum in the northern and central areas and the lowest in eastern central areas. The major parameter affecting this high value was the higher precipitation rate in this month (Fig. 6.7).

Fig. 6.7

Average deposited rates of ⁷Be in April (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Ratqah Roudhatain Liyah Salmiya	Salmi Atraf Kabd Sulaybiyah Wafra Farms

The monthly ⁷Be deposited rates in Kuwait during May 2010–2011 reveal a range from 27 to 69 Bq m⁻², with a maximum in the southern, eastern and northern areas and the lowest in the southern areas. The high values are attributed to the high precipitation rates this month that increased the dust washout (Fig. 6.8).

Fig. 6.8

Average deposited rates of ⁷Be in May (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Salmi Shegaya Dibdibah Huwaymilyah Ubayriq	Sulaybiyah Wafra Farms Salmiya Khiran KhurFawaris

The monthly ⁷Be deposited rates in Kuwait during June 2010–2011 reveal a lower rate than previous months, with a range from 4.23 to 17.32 Bq m⁻². The maximum rates were in the northern and western areas, while the lowest were in the southern and eastern areas. The predominant wind direction for this month was northwesterly, with no precipitation events (Fig. 6.9).

Fig. 6.9

Average deposited rates of ⁷Be in June (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Ratqah Dibdibah Subiyah Ubayriq	Liyah Wafra Farms Salmi Khiran KhurFawaris

Similar to June, the monthly ⁷Be deposited rates in Kuwait during July 2010–2011 reveal lower rates than previous months, with a range from 3.71 to 11.78 Bq m⁻². The maximum rates were in the northern eastern areas and the lowest in the southern and northeastern areas. The predominant wind direction for this month was northwesterly, with no precipitation events to impact wind from other directions (Fig. 6.10).

Fig. 6.10

Average deposited rates of ⁷Be for July (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Salmi Shegaya Dibdibah Ubayriq Bubiyan Island	Liyah Wafra Farms Huwaymilyah Khiran KhurFawaris

Similar to June and July, the monthly ⁷Be deposited rates in Kuwait during August 2010–2011 reveal a range from 3.66 to 29.49 Bq m⁻², with a maximum in the northern areas and the lowest in the southeastern area (Fig. 6.11).

Fig. 6.11

Average deposited rates of ⁷Be in August (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Ratqah Roudhatain Um Niqa Huwaymilyah	Um Madafi’ Wafra Farms Subiyah Salmi Atraf

Similar to the summer months, the monthly ⁷Be deposited rates in Kuwait during September 2010–2011 reveal low rates, ranging from 2.44 to 11.6 Bq m⁻², with the maximum in the northern areas and the lowest in the southern and southeastern areas (Fig. 6.12).

Fig. 6.12

Average percentages of ⁷Be in September (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Ratqah Roudhatain Dibdibah Huwaymilyah	Salmi Wafra Farms Shegaya Khiran KhurFawaris

Similar to the summer months, the monthly ⁷Be rates deposited in Kuwait during October 2009–2010 reveal a lower rate, ranging from 5.59 to 16.09 Bq m⁻², with a maximum in northeast areas, and lowest in the southern areas (Fig. 6.13).

Fig. 6.13

Average deposited rates of ⁷Be in October (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Salmi Shegaya Ubayriq Dibdibah Salmiya	Liyah Wafra Farms Urayfijan Khiran KhurFawaris

The monthly ⁷Be deposited rates in Kuwait during November 2009–2010 reveal moderate rates that range from 4.53 to 48.04 Bq m⁻², with the maximum in the central areas and the lowest in the southern, northern, and northwestern regions. The predominant wind direction was northwesterly at a minimum speed (Fig. 6.14).

Fig. 6.14

Average deposited rates of ⁷Be in November (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Shegaya Ubayriq Dibdibah Liyah Atraf	Abdulli Subiyah Urayfijan Khiran KhurFawaris

The monthly ⁷Be rates deposited in Kuwait during December 2009–2010 reveal moderate rates that range from 3.69 to 46.96 Bq m⁻², with the maximum in the central and central western areas and the lowest in the central southern areas. The predominant wind direction was northwesterly at high speed (Fig. 6.15).

Fig. 6.15

Average deposited rates of ⁷Be in December (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Gudhi Ubayriq Dibdibah Liyah Salmiya	Bubiyan Island Subiyah Sulaybiyah Kabd Atraf

Annual Deposited Rates of ¹³⁷Cs

The average annual ¹³⁷Cs rates deposited in Kuwait from October 2009 to August 2011 varied from 0.2 to 4.18 Bq m⁻², with an average of 4.76 Bq m⁻². The maximum rates were in southwestern areas. The ¹³⁷Cs rates deposited gradually decreased from the interior to the coastal areas, where they reached the minimum value. The predominant annual wind direction was northwesterly (Fig. 6.16).

Fig. 6.16

Average deposited rates of ¹³⁷Cs in (Oct 2009–Aug 2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Salmi Shegaya Ubayriq Dibdibah Um Qudayr	Ratqa Sulaybiyah Bubiyan Island Subiyah Failaka Island

Monthly Deposited Rates of ¹³⁷Cs

The monthly ¹³⁷Cs rates deposited in Kuwait during January 2010–2011 reveal a range from 0.1 to 0.39 Bq m⁻², with the maximum in central and southwestern areas and the lowest in southern areas of the Wafra Farms. The predominant wind direction for this month was northwesterly, with high wind speed sometimes (Fig. 6.17).

Fig. 6.17

Average deposited rates of ¹³⁷Cs in January (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Um Al Madafi’ Ratqah	Salmi Subiyah Sulaybiyah Khiran KhurFawaris

The monthly ¹³⁷Cs deposited rates in Kuwait during February 2010–2011 varied from 0.21 to 0.54 Bq m⁻², with two high deposition rate spots. This possibly happened because of the effect of the dust storms in this month. The predominant wind direction for this month was northwesterly, and the precipitation rates were low (Fig. 6.18).

Fig. 6.18

Average deposited rates of ¹³⁷Cs in February (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Salmi Shegaya Ubayriq Dibdibah Salmiya	Ratqah Liyah Roudhatain Sulaybiyah Atraf

The monthly ¹³⁷Cs rates deposited in Kuwait during March 2010–2011 reveal a high range that varied from 0.26 to 2.35 Bq m², with the maximum in the southwestern area and the lowest in the northern and southern regions. The predominant wind direction for this month was northwesterly, with high speed sometimes. However, the highest deposition flux was reported in this month due to the effect of the exotic storm that hit Kuwait, in addition to the high precipitation recorded (Fig. 6.19).

Fig. 6.19

Average deposited rates of ¹³⁷Cs in March (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Kabd Shegaya Ubayriq Dibdibah Um Qudayr	Ratqa Subiyah Bubiyan Island Salmiya Wafra Farms

The monthly ¹³⁷Cs rates deposited in Kuwait during April 2010–2011 ranged from 0.67 to 1.4 Bq m⁻², which is considered high, but it is less than March due to lower precipitation. The predominant wind direction was northwesterly, with a high wind speed of northeasterly, easterly, and southeasterly direction (Fig. 6.20).

Fig. 6.20

Average deposited rates of ¹³⁷Cs in April (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Shegaya Ubayriq Dibdibah Huwaymilyah Um Al Madafi’	Subiyah Bubiyan Island Sulaybiyah Kabd Jal Al Zur

The monthly ¹³⁷Cs rates deposited in Kuwait during May 2010–2011 ranged from 0.22 to 2.23 Bq m⁻², with the maximum in the southeastern and central regions. The lowest deposition fluxes were in the southern and eastern areas. However, the slightly high deposition flux in this month was due to the effect of the exotic storm that hit Kuwait on March 25, 2011 (Fig. 6.21).

Fig. 6.21

Average deposited rates of ¹³⁷Cs in May (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Shegaya Ubayriq Dibdibah Huwaymilyah Liyah	Subiyah Bubiyan Island Salmiya Wafra Farms Shuaiba

The monthly ¹³⁷Cs deposited rates in Kuwait during June 2010–2011 display similar rates to previous months, but with lower minimum rates, the range varied from 0.06 to 1.3 Bq m⁻². The maximum rates were in southeast areas, and the lowest was in central areas. The predominant wind direction for this month was northwesterly, with no precipitation events (Fig. 6.22).

Fig. 6.22

Average deposited rates of ¹³⁷Cs in June (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Shegaya Ubayriq Dibdibah Um Qudayr Liyah	Kabd Abdulli Atraf Mutla Wafra Farms

The monthly ¹³⁷Cs rates deposited in Kuwait during July 2010–2011 showed similar rates to the other summer months. The range of deposition flux varied between 0.09 and 1.39 Bq m⁻². The maximum rates were in northeastern areas and the lowest in southern and northeastern areas. The predominant wind direction for this month was northwesterly, with no precipitation events that impact wind from other directions (Fig. 6.23).

Fig. 6.23

Average deposited rates of ¹³⁷Cs in July (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Shegaya Ubayriq Dibdibah Um Qudayr Huwaymilyah	Abdulli Ratqah Um Al Madafi’ Salmiya Bubiyan Island

The monthly ¹³⁷Cs rates deposited in Kuwait during August 2010–2011 showed similar rates in June and July, with a range that varied from 0.07 to 1.23 Bq m⁻², with the maximum in the southwestern areas and the lowest in the southern areas (Fig. 6.24).

Fig. 6.24

Average deposited rates of ¹³⁷Cs in August (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Shegaya Ubayriq Dibdibah Um Qudayr Huwaymilyah	Abdulli Ratqah Um Al Madafi’ Salmiya Bubiyan Island

Similar to the summer months, the monthly ¹³⁷Cs rates deposited in Kuwait during September 2010–2011 ranged from 0.05 to 0.87 Bq m⁻², with the maximum in southwestern areas and the lowest in northern and central areas. The predominant wind direction in this month was northwesterly, with no contribution from other directions (Fig. 6.25).

Fig. 6.25

Average deposited rates of ¹³⁷Cs in September (2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Um Qudayr Liyah	Abdulli Ratqah Um Al Madafi’ Sulaybiyah Wafra Farms

Similar to the summer months, the monthly ¹³⁷Cs rates deposited in Kuwait during October 2010–2011 ranged from 0.07 to 0.72 Bq m⁻², with the maximum in southwestern areas and the lowest in northern and central eastern areas. The predominant wind direction in this month was northwesterly, with no contribution from other directions (Fig. 6.26).

Fig. 6.26

Average deposited rates of ¹³⁷Cs in October (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Um Qudayr Salmi	Um Al Madafi’ Sulaybiyah Wafra Farms Salmiya Bubiyan Island

The monthly ¹³⁷Cs rates deposited in Kuwait during November 2009–2010 showed moderate rates ranging from 0.06 to 1.54 Bq m⁻², with the maximum in the central and eastern areas and the lowest in southern areas. The predominant wind direction was northwesterly with minimum speed (Fig. 6.27).

Fig. 6.27

Average deposited rates of ¹³⁷Cs in November (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Shegaya Salmi	Ratqah Sulaybiyah Wafra Farms Salmiya Bubiyan Island

The monthly ¹³⁷Cs rates deposited in Kuwait during December 2009–2010 reveals lower rates than during summer. The deposition rates varied from 0.04 to 0.17 Bq m⁻², with the maximum value observed along the transect from the central to southwestern areas. The predominant wind direction was northwesterly, with high speed at times (Fig. 6.28).

Fig. 6.28

Average deposited rates of ¹³⁷Cs in December (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Um Al Madafi’ Liyah	Abdulli Subiyah KhurFawaris Khiran Wafra Farms

Annual Deposited Rates of ⁴⁰K

The average annual ⁴⁰K deposited rates in Kuwait from October 2009 to August 2011 varied from 74 to 557 Bq m⁻², with an average of about 160 Bq m⁻². The maximum rates were found in the southwestern areas. The ⁴⁰K deposited rates gradually decreased from the interior to the coastal areas, where it reached the minimum. The predominant annual wind direction was northwesterly (Fig. 6.29).

Fig. 6.29

Average deposited rates of ⁴⁰K in (Oct 2009–Aug 2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Um Eish Liyah	Abdulli Subiyah Atraf Salmiya Wafra Farms

Monthly Deposited Rates of ⁴⁰K

The monthly ⁴⁰K deposited rates in Kuwait during January 2010–2011 ranged from 1.14 to 15.62 Bq m⁻², with the maximum in southeastern and western areas, and the lowest was in the central areas. The predominant wind direction for this month was northwesterly, with high wind speed at times (Fig. 6.30).

Fig. 6.30

Average deposited rates of ⁴⁰K in January (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Salmi Wafra Farms	Abdulli Subiyah Liyah Salmiya Sulaybiyah

The monthly ⁴⁰K rates deposited in Kuwait during February 2010–2011 varied from 3.13 to 23.0 Bq m⁻², with a high deposition rate noted in southeastern areas. This possibly happened because of dust storms that occurred in this month. The predominant wind direction for this month was northwesterly, and the precipitation rates were low (Fig. 6.31).

Fig. 6.31

Average deposited rates of ⁴⁰K in February (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Um Qudayr	Abdulli Subiyah Um Al Madafi’ Salmiya Sulaybiyah

The monthly ⁴⁰K rates deposited in Kuwait during March 2010–2011 had a high range that varied from 5.19 to 96.27 Bq m⁻², with the maximum in the southwestern area and the lowest in the northern and southern areas. The predominant wind direction for this month was northwesterly, with high speed registered at times. However, the highest deposition flux was reported in this month because of the effect of the exotic storm that hit Kuwait, in addition to high precipitation (Fig. 6.32).

Fig. 6.32

Average deposited rates of ⁴⁰K in March (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Um Qudayr	Abdulli Subiyah Wafra Farms Salmiya Bubiyan Island

The monthly ⁴⁰K rates deposited in Kuwait during April 2010–2011 ranged from 12.88 to 69.77 Bq m⁻², which is considered high but is lower than the rates in March due to lower precipitation rates. A spot with high deposition rates was found in the central areas. The predominant wind direction was northwesterly, with a high wind speed of northeastern, eastern, and southeastern wind contribution. The critical dynamic weather due to Koss and Sarrayat that occurred in spring contributed toward the high deposition rates (Fig. 6.33).

Fig. 6.33

Average deposited rates of ⁴⁰K in April (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Gudhi	Abdulli Subiyah Wafra Farms Shuaiba Bubiyan Island

The monthly ⁴⁰K rates deposited in Kuwait during May 2010–2011 ranged from 5.12 to 70.63 Bq m⁻², with the maximum in southeastern and central areas. This range is similar to the other spring months, in which the critical dynamics weather due to Koss and Sarrayat contributed toward high deposition rates. The lowest deposition fluxes were in southern and eastern areas. However, the high deposition flux this month was due to the effect of the exotic storm that hit Kuwait on March 25, 2011 (Fig. 6.34).

Fig. 6.34

Average deposited rates of ⁴⁰K in May (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Kabd	Abdulli Jal Al Zur Wafra Farms Shuaiba Bubiyan Island

The monthly ⁴⁰K deposited rates in Kuwait during June 2010–2011 had similar rates as previous months, but with lower minimum rates, the range varied from 4.53 to 60.43 Bq m⁻². The maximum rates were in southeastern areas, and the lowest was in coastal areas. The predominant wind direction for this month was northwesterly, with no precipitation events (Fig. 6.35).

Fig. 6.35

Average deposited rates of ⁴⁰K in June (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Um Qudayr	Abdulli Salmi Salmiya Sulaybiyah Kabd

The monthly ⁴⁰K rates deposited in Kuwait during July 2010–2011 were similar to the other summer months. The range of deposition varied between 2.31 and 61.76 Bq m⁻². The maximum rates were in southeastern areas, and the lowest rates were in southern and northeastern areas. The predominant wind direction for this month was northwesterly, with no precipitation events or impact wind from other directions (Fig. 6.36).

Fig. 6.36

Average deposited rates of ⁴⁰K in July (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Um Qudayr	Abdulli Subiyah Salmiya Salmi Bubiyan Island

The monthly ⁴⁰K rates deposited in Kuwait during August 2010–2011 had a similar trend to June and July, with a low range that varied from 2.23 to 27.63 Bq m⁻², with the maximum in southwestern areas. The predominant wind direction was northwesterly, with a minor contribution made by southeastern wind (Fig. 6.37).

Fig. 6.37

Average deposited rates of ⁴⁰K in August (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Ubayriq Dibdibah Liyah Bubiyan Island	Abdulli Salmi Salmiya Sulaybiyah Wafra Farms

Similar to the summer months, the monthly ⁴⁰K rates deposited in Kuwait during September 2010–2011 ranged from 1.55 to 41.61 Bq m⁻², with the maximum recorded in southwestern areas and the lowest recorded in northern and central coastal areas. The predominant wind direction in this month was northwesterly, with no contribution from other directions (Fig. 6.38).

Fig. 6.38

Average deposited rates of ⁴⁰K in September (2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Ubayriq Dibdibah Liyah Shegaya Huwaymilyah	Abdulli Salmi Salmiya Bubiyan Island Wafra Farms

Similar to summer, the monthly ⁴⁰K rates deposited in Kuwait during October 2010–2011 ranged from 1.56 to 61.32 Bq m⁻², with the maximum in southwestern areas and the lowest in northern and central eastern areas. The predominant wind direction of this month was northwesterly, with no contribution from other directions (Fig. 6.39).

Fig. 6.39

Average deposited rates of ⁴⁰K in October (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Ubayriq Dibdibah Liyah Ratqah Huwaymilyah	Subiyah Salmi Salmiya Bubiyan Island Wafra Farms

The monthly ⁴⁰K rates deposited in Kuwait during November 2009–2010 were low, ranging from 1.28 to 21.28 Bq m⁻², with the maximum in the central and southwestern areas and the lowest in the southern and northern areas. The predominant wind direction was northwesterly, with high speed recorded at times (Fig. 6.40).

Fig. 6.40

Average deposited rates of ⁴⁰K in November (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Ubayriq Dibdibah Liyah Shegaya Huwaymilyah	Abdulli Subiyah Salmiya Bubiyan Island Wafra Farms

The monthly ⁴⁰K rates deposited in Kuwait during December 2009–2010 were moderate and ranged from 1.91 to 31.12 Bq m⁻², with the maximum in the southwestern areas and the lowest in the southern areas. The predominant wind direction was northwesterly, with high speed at times (Fig. 6.41).

Fig. 6.41

Average deposited rates of ⁴⁰K in December (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Ubayriq Dibdibah Liyah Shegaya Huwaymilyah	Abdulli Subiyah Salmi Bubiyan Island Wafra Farms

Annual Deposited Rates of ²¹⁰Pb

The average annual ²¹⁰Pb rates deposited in Kuwait from October 2009 to August 2011 varied from 107 to 233 Bq m⁻², with an average of about 134 Bq m⁻², which is close to the reported ²¹⁰Pb annual deposition rates on the continent between 10° and 30° N latitude (160 Bq m⁻²). The maximum rates were in the southeastern part of the country (Shaqaya). The minimum rates were along the coastal areas. A maximum of ²¹⁰Pb deposition flux was revealed in the spring months; when the precipitation was high, the predominant annual wind direction was northwesterly (Fig. 6.42).

Fig. 6.42

Average deposited rates of ²¹⁰Pb in (October 2009–August 2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Ubayriq Dibdibah Liyah Shegaya Huwaymilyah	Abdulli Subiyah Salmi Bubiyan Island Wafra Farms

Monthly Deposited Rates of ²¹⁰Pb

The monthly ²¹⁰Pb deposited rates in Kuwait during January 2010–2011 ranged from 4.9 to 16.73 Bq m⁻², with the maximum in central areas and the lowest in southern areas. The predominant wind direction for this month was northwesterly (Fig. 6.43).

Fig. 6.43

Average deposited rates of ²¹⁰Pb in January (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Liyah Ratqah Um Al Madafi’	Salmi Sulaybiyah KhurFawaris Khiran Wafra Farms

The monthly ²¹⁰Pb rates deposited in Kuwait during February 2010–2011 ranged from 9.39 to 16.6 Bq m⁻², with three maximum spots. This is possibly visible because of the effect of dust storms this month. The predominant wind direction for this month was northwesterly, and the precipitation rates were lower (Fig. 6.44).

Fig. 6.44

Average deposited rates of ²¹⁰Pb in February (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Bubiyan Island Dibdibah Liyah Ratqah Subiyah	Salmi Sulaybiyah Liyah Atraf Kabd

The monthly ²¹⁰Pb deposited rates in Kuwait during February 2010–2011 ranged from 9.39 to 16.6 Bq m⁻², with three maximum spots. This is possibly visible because of the effect of dust storms this month. The predominant wind direction for this month was northwesterly, and the precipitation rates were lower (Fig. 6.45).

Fig. 6.45

Average deposited rates of ²¹⁰Pb in March (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Liyah Ubayriq Um Al Madafi’	Salmi Subiyah Ratqah Salmiya Wafra Farms

The monthly ²¹⁰Pb deposited rates in Kuwait during April 2010–2011 ranged from 22.36 to 41.38 Bq m⁻². The major parameter affecting this high value was the high precipitation rate. The predominant wind direction was northwesterly, with a high wind speed of northeastern, eastern, and southeastern wind contribution (Fig. 6.46).

Fig. 6.46

Average deposited rates of ²¹⁰Pb in April (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Liyah Huwaymilyah Dibdibah Ratqah Doha	Salmi Sulaybiyah Subiyah Kabd Bubiyan Island

The monthly ²¹⁰Pb rates deposited in Kuwait during May 2010–2011 ranged from 8.19 to 30.44 Bq m⁻², with the maximum in the southeastern and central areas. The lowest deposition fluxes were in the southern and eastern areas. However, the slightly high deposition flux in this month was because of the effect of the exotic that storm hit Kuwait on March 25, 2011 (Fig. 6.47).

Fig. 6.47

Average deposited rates of ²¹⁰Pb in May (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Liyah Ubayriq Kabd	Doha Subiyah Ratqah Salmiya Wafra Farms

The monthly ²¹⁰Pb rates deposited in Kuwait during June 2010–2011 were lower compared with previous months, with a range from 4.17 to 20.2 Bq m⁻². The maximum rates were in the southeastern areas and the lowest in the central areas. The predominant wind direction for this month was northwesterly, with no precipitation events (Fig. 6.48).

Fig. 6.48

Average deposited rates of ²¹⁰Pb in June (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Liyah Ubayriq Bubiyan Island	Doha Sulaybiyah Ratqah Salmi Wafra Farms

Similar to June, the monthly ²¹⁰Pb deposited rates in Kuwait during July 2010–2011 were lower when compared with previous months. The range of deposition fluxes varied between 3.09 and 15.48 Bq m⁻². The maximum rates were in the northeastern areas and the lowest in the southern and northeastern areas. The predominant wind direction for this month was northwesterly, with no precipitation events or impact wind from other directions (Fig. 6.49).

Fig. 6.49

Average deposited rates of ²¹⁰Pb in July (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Liyah Ubayriq Kabd	Doha Subiyah Ratqah Salmiya Bubiyan Island

The monthly ²¹⁰Pb deposited rates in Kuwait during August 2010–2011 were lower than in June and July, with a range that varied from 2.16 to 9.72 Bq m⁻², with the maximum in the northern and southwestern areas, and the lowest within the transect along the northwesterly wind corridor (Fig. 6.50).

Fig. 6.50

Average deposited rates of ²¹⁰Pb in August (2010–2011)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Ratqah Ubayriq Bubiyan Island	Doha Sulaybiyah Um Al Madafi’ Salmi Wafra Farms

Similar to the summer months, the monthly ²¹⁰Pb deposited rates in Kuwait during September 2010–2011 had low rates that ranged from 1.8 to 10.64 Bq m⁻², with the maximum in the northwestern areas and the lowest in the southern and southwestern areas. The predominant wind direction in this month was northwesterly, with no contribution from other directions (Fig. 6.51).

Fig. 6.51

Average deposited rates of ²¹⁰Pb in September (2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Liyah Ubayriq Kabd	Doha Sulaybiyah Failaka Island Salmi Wafra Farms

Similar to the summer months, the monthly ²¹⁰Pb deposited rates in Kuwait during October 2009–2010 showed low rates, with a range that varied from 2.52 to 8.74 Bq m⁻², with the maximum in the southeastern and northern areas and the lowest along the northwesterly wind corridor (Fig. 6.52).

Fig. 6.52

Average deposited rates of ²¹⁰Pb in October (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Abdulli Dibdibah Ratqah Ubayriq Shegaya	Doha Sulaybiyah Um Al Madafi’ Khiran Wafra Farms

The monthly ²¹⁰Pb deposited rates in Kuwait during November 2009–2010 were moderate, ranging from 5.25 to 14.2 Bq m⁻², with the maximum in the central and southeastern areas and the lowest in the southern areas. The predominant wind direction was northwesterly at a minimum speed (Fig. 6.53).

Fig. 6.53

Average deposited rates of ²¹⁰Pb in November (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Huwaymilyah Dibdibah Doha Ubayriq Bubiyan Island	Abdulli Sulaybiyah Ratqah Salmi Wafra Farms

The monthly ²¹⁰Pb rates deposited in Kuwait during December 2009–2010 were similar to November. The rates varied from 4.74 to 14.06 Bq m⁻², with the maximum in the southwestern and central eastern areas. The predominant wind direction was northwesterly, with high speed at times (Fig. 6.54).

Fig. 6.54

Average deposited rates of ²¹⁰Pb in December (2009–2010)

Areas with high radionuclide concentration	Areas with low radionuclide concentration
Doha Dibdibah Ratqah Ubayriq Um Al Madafi’	Ratqah Sulaybiyah Salmi Khiran Wafra Farms