Mr. Henderson researches nutrient cycling in coastal systems and uses radioisotope tracers to help quantify groundwater inputs of trace metals and inorganic nutrients to the ocean. This latter process has significant societal relevance due to its potential to negatively affect the ecological balance in coastal systems and lead to eutrophication. Beyond the coastal realm, Mr. Henderson has contributed to pioneering research on the use of radium isotopes as tools for quantifying vertical and horizontal mixing rates that control the distribution of trace elements and isotopes (TEIs) in the ocean. The data obtained from the GEOTRACES project will help quantify lateral mixing processes between shelf waters and open ocean on the scale of days to weeks using short lived radium isotopes (223Ra, 224Ra). The longer lived 226Ra and 228Ra will be used to study the fate of trace metals in hydrothermal plumes in the deep ocean. These measurements made aboard the R/V Roger Revelle and back at WHOI will help in determining the source and magnitude of TEI inputs in the Pacific Ocean.