The Absolute Salinity of seawater diluted by riverwater

Seawater is often assumed to have a constant relative composition of dissolved matter, so that a measurement of one property (e.g., electrical conductivity) can be used with a suitable correlation equation to estimate other properties like density. However, small variations in the relative composition do occur, and the associated variation in seawater properties can be orders of magnitude larger than would be naively assumed from measurement precision. The new seawater standard TEOS-10 provides a mechanism to account for these compositional variations, and correction factors are provided suitable for measurements in the open ocean when composition changes occur due to specific biogeochemical processes. Here variations due to the addition of river salts are considered by combining numerical models for the conductivity, salinity, and density of arbitrary aqueous solutions with a global database of river chemistry. It is found that calculated densities in river diluted waters will typically be too low by 0.02-0.3 kg m− 3, but with significant spatial variability.