tendency_of_mole_concentration_of_particulate_organic_matter_expressed_as_carbon_in_sea_water_due_to_gross_primary_production_by_diatoms mol m-3 s-1 [MM3s] The phrase "tendency_of_X" means derivative of X with respect to time. "Mole concentration" means number of moles per unit volume, also called "molarity", and is used in the construction "mole_concentration_of_X_in_Y", where X is a material constituent of Y. A chemical species or biological group denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". Particulate means suspended solids of all sizes. Particulate organic matter (also called POM) means organic matter that does not pass through a reference filter pore size. "Organic matter" means material which is derived from living organisms or from their biological activities. Organic matter consists of carbon-based compounds. 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. "Production of carbon" means the production of biomass expressed as the mass of carbon which it contains. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Gross primary production is the rate of synthesis of biomass from inorganic precursors by autotrophs ("producers"), for example, photosynthesis in plants or phytoplankton. The producers also respire some of this biomass and the difference is "net_primary_production". Diatoms are phytoplankton with an external skeleton made of silica. Phytoplankton are algae that grow where there is sufficient light to support photosynthesis.