Date of Award

4-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Environmental Science

First Advisor

Sulaiman Ali Alaabed Alkaa

Second Advisor

Mohamed El Tokhibi

Third Advisor

Walid El Mowafi

Abstract

Geochemical, mineralogical and natural radiation analysis techniques were used for establishment of geochemical and radiological baseline around Barakah Nuclear Power Plant, UAE. The natural radioactivity concentrations of 238U (226Ra), 232Th and 40K were measured for soil, shore and bottom sediment samples, using gamma spectrometry equipped with HPGe detector. In addition, alpha spectrometry was used to measure 234U/238U ratio for some selected samples. Furthermore, inductively coupled plasma atomic emission spectroscopy was used to measure the concentrations of heavy metals and Rare Earth Elements (REE). The grain size of the samples ranged from fine to coarse sand. The inverse relationship between grain size and heavy metal contaminations was validated. The results indicated the mean concentrations of heavy metals and REE are much higher in soil samples compared to bottom sediments, which in turn relatively higher than shore samples. All heavy metals concentrations were significantly below the UAE soil contamination safe limits. The levels of heavy metals and REE reported in the UAE were lower than the levels reported in the soil, shore and bottom sediments of several countries around the world. Enrichment factor calculated for heavy metals shows no to moderate enrichment (As and Cd), while the contamination factor (CF) was CF<1 which indicates low contamination factor. Geoaccumulation results suggest uncontaminated area. Furthermore, the pollution load index, >1, indicates no pollution in the area. With exception of La in shore samples, all the REE show no enrichment. Contamination factor for REE indicates a low contamination factor and geoaccumulation results indicate that the studied area was uncontaminated. Moreover, the pollution load index indicates no pollution in the area.

The measured gamma activity concentrations in shore-sediment samples are much lower comparing to those concentrations in soil and bottom sediments. The average activity concentrations of 238U (226Ra) are 15.68±0.56, 4.43±0.39 and 4.73±0.47 Bq/kg, for 232Th are 8.3±0.23, 1.68±0.17 and 1.83±0.24 Bq/kg and for 40K, are 349.72±11.76, 106.3±7.27 and 105.23±10.03 Bq/kg in soil, shore and bottom sediment samples, respectively. Anthropogenic radionuclide 137Cs is low than the detection limit in the studied area. The 234U/238U activity ratios show wide range from 0.59 to 2.24 indicating effects of sources and in situ processes. In addition, the hazard parameters such as Radium equivalent and absorption dose were estimated and all are below the world average. The spatial distribution for heavy metals, REE and natural radionuclides was generally more compact in the south compared to the north, with less severe contamination in the east and west. Relationships between heavy metals, REE and natural radioactivity concentrations were investigated and varied between soil, shore and bottom sediment samples. The previous relationships may indicate that uranium and thorium have detrital sources possibly associated with silicate minerals.

Comments

Research Relevance and Potential Impact

  1. The study is an original new work that has not been done before in the UAE, establishing a reference data about the geo-environmental chemistry and radiation level of Baraka area.
  2. It created an initial baseline radiometric map of the studied area prior to the running of Barakah Nuclear Power Plant (BNPP).
  3. Recorded heavy metals distribution at the study area can be used as an indicator of any later contamination brought by water or wind after BNPP functioning.
  4. The collected radiological data forms an initiative benchmark reference for the radiation hazardous assessment after BNPP starts operating.
  5. The study has initiated a track for further work in Baraka progressive assessment the radiation protection.

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