"Mass concentration means mass per unit volume and is used in the construction mass_concentration_of_X_in_Y, where X is a material constituent of Y. A chemical or biological species denoted by X may be described by a single term such as \"nitrogen\" or a phrase such as \"nox_expressed_as_nitrogen\". The phrase \"expressed_as\" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. Diatoms are single-celled phytoplankton with an external skeleton made of silica. Phytoplankton are algae that grow where there is sufficient light to support photosynthesis."@en . . . "SDN:P07::CF12N248" . "mass_concentration_of_diatoms_expressed_as_nitrogen_in_sea_water"@en . . . "false" . . "2018-12-17 17:17:12.0" . "SDN:P07::CF12N248" . . . "" . "accepted"@en . . "2018-12-17 17:17:12.0" . . "2" . "2" . "SDN:P07::CF12N248" .