Data were collected on three cruises on the Brazos River Plume in the Northern Gulf of Mexico. Cores were collected from: 11 stations on September 10, 2017; 23 stations on October 29, 2017; and 26 stations on July 12, 2018. The September 2017 cruise was conducted on R/V Pelican (PE18-09); the two subsequent cruises were conducted on R/V Trident.
On each cruise, a series of box cores were collected in a grid pattern. From those box cores, a series of sub-cores were collected. Those included: x-radiograph trays, a 3-inch aluminum and/or polycarbonate core, and a 6-inch core. They were stored in a refrigerator at 2 °C and later split into 1 cm sections, x-rayed, and stored in bags until further analysis.
To collect water content, a basic oven was used at 60 °C. They were dried in pre-weighed aluminum tins, and then the water content was calculated after weighing the dry weight.
The grain size was processed in a Malvern Mastersizer 2000 that uses laser diffraction to analyze the grains.
The Mercury content was analyzed in a Milestone DMA-80 that combusts the sample to get a total mercury content.