Correlation of naturally occurring radioactive materials (NORM) concentration in Langat River and basin sediment / Tuan Asmaa Tuan Resdi

Naturally occurring radioactive material (NORM) comprises long-lived nuclides which can be harmful to human due to long-term exposure. Furthermore, correlation of observed natural radionuclides concentration in the river sediment with river sediment discharge will allow its spatial and temporal distribution to be predicted. NORM studies in Malaysia are reviewed and compiled to provide the spatial observation of naturally occurring radioactive material in the country and to identify hotspot locations. There is strong correlation between Ra-226 and Ra-228 but no discernible correlation between radioactivity concentration in catchment soil and river sediment sample for the same element. In general, radionuclide activity increases in river sediment in the down-river direction which may be attributed to catchment soil loss. There is insufficient data on river sediment discharge to support the claim conclusively. Linear log-transformed equation is found to give the best correlation between river sediment discharge and streamflow with 1-day lead. The river sediment discharge derived shows good agreement with the monsoonal effect and total basin sediment yield is validated against published literature where errors are primarily attributed to extreme events. Over a fouryear period, the Langat River basin has been investigated for the correlation between natural radionuclide activity concentrations in river sediment and suspended sediment discharge. Analysis of long-term correlation between quarterly natural radionuclides concentration observation with river sediment discharge is generally poor. However, examination of the seasonal variation shows good correlation of natural radionuclides concentration and river sediment discharge in the months of March and August/September, corresponding to the pre-storm seasons.