About: http://webisa.webdatacommons.org/345845457

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Other elements such as iron, copper and zinc are sensitive indicators of terrestrial seawater but can not be measured accurately in ballast tanks due to contamination from the ship's structural materials.
http://www.w3.org/ns/prov#wasQuotedFrom	si.edu