There is extensive contamination of the aquatic environment when rivers and streams flow through areas of high human activities such as industrial cities and major towns. These contaminations may include enhanced background levels of naturally occurring radioactive materials resulting from rapid urbanization and other human activities. The natural radionuclides (40K, 238U (226Ra) and 232Th (228Ra)) contents of farm-raised and wild catfish in five fish farms and three major rivers within Ibadan metropolis have been studied using gamma spectrometry. The results indicate that the average committed effective doses from the ingestion of the two sets of catfishes are 104 ± 37 and 104 ± 32 μSv/y for farm-raised and wild catfish, respectively. It can be concluded that the consumption of the catfishes poses no immediate radiological hazards to the population of the study area.

中文翻译：

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尼日利亚伊巴丹农场养殖和野生鲶鱼中天然放射性核素的有效剂量

当河流和溪流流经工业城市和主要城镇等人类活动频繁的地区时，水环境受到广泛污染。这些污染可能包括由于快速城市化和其他人类活动导致的天然放射性物质的背景水平升高。已使用伽马光谱法研究了伊巴丹大都市内五个养鱼场和三个主要河流中养殖和野生鲶鱼的天然放射性核素（40K、238U (226Ra) 和 232Th (228Ra)）含量。结果表明，养殖和野生鲶鱼摄入两组鲶鱼的平均承诺有效剂量分别为 104 ± 37 和 104 ± 32 μSv/y。