利用放射性I131和S35研究松沙土土体和地下水盐分的运动

盐碱土表土盐分积累的来源,不仅与地下水埋深及其矿化度有关,而且与土体盐分再分配有关。本试验是利用放射性I¹³¹(NaI¹³¹)和S³⁵(Na₂S³⁵O₄)的示踪方法,探讨在含盐地下水正常补给情况下,土体和地下水盐分运行的一些规律,有助于全面了解表土积盐的过程。

INVESTIGATION ON THE MOVEMENT OF SOLUBLE SALTS IN SOIL COLUMNS BY RADIOISOTOPIC METHOD

Columns of loosely packed sandy soil of different heights were used in present investrgation.The salt movement in the soil columns was simulated with labelled NaI¹³¹.The columns were placed in a salt solution of labelled Na₂S³⁵O₄ (5 gm/l) simulating the ground water.The sail was exposed to evaporation.The movement of soluble salts in soil and solution were studied by radioidobopic method.Results obtained are anmmarized as follows:1) The content of soluble salts in soil phase rised with the capillary water during evaporation from soil surface.A higher concentration of salts appeared in the front of the capillary water.The thickness of salts concentrated layer increased following the continuous evaporation of soil water,and finally a layer of salt accumulation was formed in the surface soil.2) The soluble salts contained in water phase also moved upwards with the rising of capillary water.The rate of its movement,however,was lower than soil salts.But the continuous rise of capillary water also induced the sulphate se,lts accumulation in the surface of the soil column.3)Accordine to the results mentioned above,it is concluded that lowerine the ground water level below the critical depth is an effective measurement for the improvement of the saline soil.At the same time,it must be considered to incorporate with other practices such as leaching of salts by irrigation,leveling of the land and increase of the application of organic manure in the soils.