Causes and effects of composition changes in the ocean

一个多世纪以来，海水中溶解物质的相对组成是固定的，因此可以用一个变量（“盐度”）来表征。这个假设主导了海洋学的所有实际方面。然而，尽管使用电导率测量盐度的常规精度可以达到+/- 2mg /kg（在新的参考成分盐度标度上），但实际海水的真实盐度可能与这些估计值相差30 mg/kg，在波罗的海可能相差90 mg/kg，在近海岸地区可能相差更多。这些误差是由于海水化学成分变化的影响而产生的。事实上，当使用与电导率相关的标准方程时，这些成分变化是估计海水热力学性质（例如密度）的最大不确定性来源。虽然我已经提出了一些基于基本物理/化学因素估计必要修正的技术，但这些技术相对来说还不成熟。这部分是由于我们对实际成分变化以及控制它们的物理、生物和化学过程的知识不足，部分是由于我们对所有天然水域的电导率/盐度/密度关系的基本理论知识的不确定性。

For more than a century the assumption that the dissolved matter in seawater has a fixed relative composition, and hence can be characterized by a single variable (the "salinity"), has dominated ALL practical aspects of oceanographic science. However, although measurements of salinity using electrical conductivity can be made routinely to a precision of +/-2 mg/kg (on the new Reference Composition Salinity Scale), the true salinities of real seawater may differ by from these estimates by up to 30 mg/kg in the open ocean, 90 mg/kg in the Baltic, and potentially much more in near-coastal areas. These errors arise due to the effects of changes in the chemical composition of seawater. These composition changes are in fact the largest source of uncertainty in estimates of the thermodynamic properties of seawater (e.g., density) when using standard equations that relate them to conductivity. Although I have proposed some techniques for estimating the necessary corrections based on fundamental physical/chemical factors, these techniques are relatively immature. This is partly due to inadequacies in our knowledge of the actual composition variations and the physical, biological, and chemical processes that control them, and partly due to uncertainties in our fundamental knowledge of the theory governing conductivity/salinity/density relationships in all natural waters.