210Po bioaccumulation and trophic transfer in marine food chains in the northern Arabian Gulf

Publication date: August 2017
Source:Journal of Environmental Radioactivity, Volume 174
Author(s): S. Uddin, S.W. Fowler, M. Behbehani, M. Metian
The tendency of ²¹⁰Po to concentrate in body tissue poses a serious concern of radiological safety. This study compiles available information and presents recent ²¹⁰Po data for the marine food web in the northern Gulf waters. Since ²¹⁰Po is concentrated in marine biota, a large number of samples of various marine organisms covering several trophic levels, from microalgae to sharks, were analyzed. ²¹⁰Po was found to be highly concentrated in several marine species with the highest ²¹⁰Po concentrations found in yellowfin tuna, i.e. 37.3–44.9, 451–548, and 1511–1693 Bq kg⁻¹ wwt in muscle, digestive system and liver, respectively. In most dissected fish samples, ²¹⁰Po showed increasing concentrations in the following order: edible tissue, gills, digestive system, liver and fecal matter. Fish feces had ²¹⁰Po concentrations several orders of magnitude higher than that in seawater, fish muscle, and the fishes' ingested food. The high ²¹⁰Po concentration in fish fecal matter suggests that the bulk of ²¹⁰Po content in fish is eventually excreted back into the environment as fecal pellets. In most fish high concentrations were noted in liver, with the highest ²¹⁰Po concentration recorded in yellowfin tuna liver. Moreover, ²¹⁰Po concentration in the soft tissue of tunicate and bryozoan samples were 872–1012 and 402–527 Bq kg⁻¹ wwt, respectively, far higher than that in fish muscle (0.04–44.9 Bq kg⁻¹ wwt). It was observed that the maximum ²¹⁰Po concentration in edible fish tissue among the fish in trophic level 2 was an order of magnitude lower than those in trophic level 3 and two orders of magnitude lower compared to fish in trophic level 4. The highest concentrations in the muscle tissue were observed in the following order: tunicate > bryozoan > mollusc > crustacean > algae > fish. Among all the biota analyzed, the highest overall concentration of ²¹⁰Po was noted in yellowfin tuna (Thunnus albacores) indicating a potential biomagnification of ²¹⁰Po in this particular top predator species. In general, ²¹⁰Po concentrations found in the commercially important fish from Kuwaiti waters were comparable to levels that have been reported for similar fish species from several other marine areas worldwide.



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