泥沙的沉速规律是泥沙运动的最简单而最基本的规律。放射性同位素示踪沙是进行这方面的测定和研究的一种有效方法。本工作是在

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In示踪沙的制备研究基础上，根据同位素示踪沙测速的原理和

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In示踪沙的特点提出的。

A method for determining settling velocity of

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In labelled sands is presented. Experiments show that in distilled water the mean settling velocity of tracer particles with a diameter of 0.9 mm is 111.50±0.48 mm/s (theoretical value being 109.2 mm/s) . This method thus provides a laboratory mean for studying the velocity

the characteristics of sediment particles settling in muddy water

which could hardly be done hitherto.