EXPERIMENTAL DESIGN AND METHODS:

Transects were conducted in a motorboat with a sample inlet device located beneath the hull that, when the boat was moving, would force water into an enclosed chamber and past the sampling probe. Dissolved oxygen, percent saturation, conductivity, temperature and pH were measured in the chamber with a Hydrolab or YSI sonde (see ANALYTICAL METHODS).  On dates when DIC and pCO2 were measured, samples were collected in the outlet line into glass bottles, and preserved with HgCl2.  As we did not need to stop at each station to obtain a sample, transects were completed quickly and represent a close to instantaneous dissolved oxygen transect of the estuary.

Calculated salinity is based upon Hydrolab_Series_4a_Manual, Section 4. Conductivity sensor, page 86 with the following formula:

Salinity = c1*SpCond^4 + c2*SpCond^3 + c3*SpCond^2 + c4*SpCond + c5 where c1 = 5.9950 x 10-8, c2 = -2.3120 x 10-5, c3 =3.4346 x 10-3, c4 = 5.3532 x 10-1, c5 = -1.5494 x 10-2.