Chemical Data for Water Samples Collected During Four Upriver Cruises on the Mississippi River Between New Orleans, Louisiana, and Minneapolis, Minnesota, May 1990-April 1992

Surface-water samples were collected approximately every 18 to 28 km relative to the water from a research vessel that was underway 24 hours a day up the Mississippi River from New Orleans, Louisiana, to Minneapolis, Minnesota, in order to study the longitudinal variability of chemicals, the cross-channel variability of chemicals, and the effects of sewage outfalls. The methods and data for computing the water discharge associated with each sample and the distance between samples collected from a moving vessel on a flowing river are explained and listed in this chapter. The product of this water discharge and the concentration of chemical constituents listed in later chapters gives the approximate flux of these chemicals. The distance between samples in the moving water permits the calculation of chemical gradients and the determination of the spatial scales of the longitudinal chemical variability.