GEOTRACES Key Parameters

“Key trace elements and isotopes” are those that are:

– micronutrients essential to life in the ocean (e.g. Fe, Zn, Cd, Cu)
– tracers of modern processes in the ocean (e.g. Al, Mn, δ15N)
– significantly perturbed by human activities (e.g. Pb) 
– used as proxies to reconstruct the past (e.g. 231Pa, 230Th, Nd isotopes)

A list of GEOTRACES Key Parameters is presented in the table below:

These parameters are expected to be measured on all GEOTRACES Section Cruises. This list does not represent a complete list of parameters of interest to GEOTRACES, however, and the programme encourages measurement of diverse other trace elements and isotopes, particularly those that fit into the categories described above. Examples of such additional parameters that are widely measured during GEOTRACES cruise include, but are not limited to: Co; Si isotopes; 234Th; and Hg concentration and speciation.

Key Parameter          Examples of use
Trace Elements
Fe Essential micronutrient
Al Tracer of Fe inputs (from mineral dust and elsewhere)
Zn Micronutrient; potentially toxic at high concentration
Mn Tracer of Fe inputs and redox cycling
Cd Essential micronutrient; palaeoproxy for nutrient content of waters
Cu Micronutrient; potentially toxic at high concentration
Stable isotopes
δ15N (nitrate) Modern and palaeoproxy for nitrate cycling
δ13C Modern and palaeoproxy for nutrient content and ocean circulation
Radioactive isotopes
230Th Constant flux monitor in sediments; tracer of modern ocean circulation and particle scavenging
231Pa Palaeoproxy for circulation and productivity; tracer of modern particle processes
Radiogenic isotopes
Pb isotopes Tracer of natural and contaminant sources to the ocean
Nd isotopes Tracer of natural sources of TEIs to the ocean
Other parameters
Stored sample To allow future work
Particles Essential transport vector for many TEIs
Aerosols Essential source of TEIs to the surface ocean