盐度定义狭义性与广义性

通过理论分析和实验验证,论述了“实用盐标”、“氯度盐标”定义的狭义性及应用范围,指出电导法和氯度法测定保守性质样品,数据正确;而测定非保守性质样品,测定值偏离绝对盐度S_a.笔者建议的“密度盐标”属于广义性质,可广泛应用于保守和非保守性质样品.密度盐标具有的优点是:(1)不受样品组成变化影响,只与溶液质量和浮力有关,测定值有高度可靠性与重现性;(2)测定大洋水盐度与现有实用盐度值相同,测定工业水盐度较实用盐度、氯度盐度值更接近绝对盐度S_a;(3)在已知溶质情况下,应用溶液膨胀系数和物质偏摩尔体积校正系数可统一溶质浓度与盐度的换算关系.

The narrow and broad senses on the salinity scale

The narrow sense and applicable limit of practical salinity scale 1978 (PSS78) and volumetric titration using silver nitrate to measure the salinity of non conservative ocean water are discussed, It is found that the salinity obtained by electrical conductivity method and chlorinity salinity method are obviously deviated from the absolute salinity ( S a), the density salinity scale (DSS98) proposed by the writers can be extensively used in conservative and non conservative water samples. The characteristics of the density salinity scale are: (1) The density salinity scale is only related to seawater mass and its buoyant effect and is not influenced by the variation of seawater composition, and so, has high reliability, and repeatability of determination. (2) The salinity values measured on the DSS98 have conservative property. For ocean water samples the salinity values are the same as those determined by the PSS78, for non conservative water samples, for example, samples from industrial sources, the salinity values are closer to the absolute salinity values in comparison with those measured by the PSS78 and the Knudsen method. (3) For a solution with given solute mass, the solution concentration can be converted into the corresponding salinity by the density salinity scale using the expansion coefficient of the solution and the calibration coefficient of the partial molar volume of the solute.