【摘要】 <正> 河口活性硅酸盐除了被稀释和被吸收外,有没有进行明显的无机化学转移?一直到最近几年,仍然是国际上争论的问题。 我们已在本研究第Ⅰ篇报导了河口活性硅含量分布;河水与无硅海水人工混合后活性硅含量变化;电解质浓度和pH值对硅酸盐溶液中活性硅含量的影响以及吸附剂影响的初步实验;证实了河水和海水混合后活性硅含量的变化主要决定于悬浮物、电解质、pH值三个因素的同时作用。我们还根据Fe（OH）₃和Al（OH）₃胶体沉淀对海水中活性硅吸附的初步实验数据,提出初步看法,认为可能河水入海后由于盐度增大和pH值提高,一方面不断生更多还原

【Abstract】 The adsorption of reactive silicate in sea water on colloidal Fe(OH)3 and A1(OH)3 precipitates has been studied quantitatively in the laboratory in order to find out the extent of the adsorption under conditions similar to those occur in natural environments, the type of adsorption process, and also the more acceptable mechanism of the silicate removal in the estuarial region.Adsorption isotherms under different Cl ‰, pH, and composition of electrolytes have been obtained and isosteric heats of adsorption have been calculated. Desorption experiments have been done by washing the adsorption residues with NaCl, Na2SO4, MgCl2 or NaOH solution. Some residues were re-dissolved by 0.02 N HC1 to determine the form of the adsorbed silicate.It was found that reactive silicate in sea water is markly adsorbed by colloidal A1(OH)3 and Fe(OH)3 precipitates. The adsorption increases with increasing Cl ‰ and pH. Although the overall isosteric heats of adsorption in sea water are in the order of 1000-2000 cal./mole, but the isosteric heats of adsorption in pure MgCl2 solution are as high as 5000-10000 cal./ mole. Practically no silicate can be washed out by all the above mentioned electrolytic solutions, and after re-dissoled by 0.02 N HC1, almost all the adsorbed silicate returns to reactive silicate form rather than polymerized silicate. This shows that the adsorption is more probably a type of chemical adsorption and the adsorbed silicate ions may form chemical bonds with Fe(OH)3 or A1(OH)3 lattices, gradually transform into their inner structure, and finally form certain kinds of insoluble ferric and/or aluminium silicates. The results give support to a proposition of the mechanism of the silicate removal in the estuarial region that the reactive silicate is partly removed by irreversible chemical adsorption on Fe(OH)3 and Al(OH)3 newly formed under higher pH and salinity, gradually transforms into stable ferric and/or aluminium silicates, and finally sinks onto sea bottom as sediment. This proposed geoebemical pattern of estuarine silicate needs to be checked with sufficient in situ oceanographic observations.更多还原