Don Martocello is a 5th year PhD student in the MIT/WHOI Joint Program in Chemical Oceanography. He is directly advised by Scott Wankel and is a proud member of the Wankel/Hansel lab groups at WHOI. Prior to grad school, Don was a geosciences major at Princeton University working with the Morel Lab studying trace metal limitation in marine heterotrophic bacteria. During his PhD, Don is exploring the effect of trace metal micronutrient availability on ammonia oxidation isotope dynamics and nitrous oxide production. Don has previously been a science team member of research cruise RR2107 where he measured nitrification rates from hydrothermal vent plumes at the Guaymas basin in the Gulf of California. On this upcoming cruise, Don hopes to tackle long-standing questions about photoinhibition of nitrification by pairing 15N tracer rate incubations with the exciting ROS sensing technology and expertise of the Hansel lab!