This International Standard specifies five methods for determining the ultimate aerobic biodegradability of organic compounds in the marine environment by aerobic microorganisms in static aqueous test systems. Standard degradation methods developed for testing in fresh water are modified and adapted to marine conditions. These methods are the DOC die-away test (ISO 7827), the closed bottle test (ISO 10707), the two-phase closed bottle test (ISO 10708), the CO2 evolution test (ISO 9439) and the CO2 headspace test (ISO 14593). The methods apply to organic compounds which a) are water-soluble under the conditions of the test used; b) are poorly water-soluble under the conditions of the test used, in which case special measures may be necessary to achieve good dispersion of the compound (see for example, ISO 10634); c) are volatile, provided that an appropriate test with suitable conditions is used; d) are not inhibitory to the test microorganisms at the concentration chosen for the tests. The presence of inhibitory effects can be determined as specified in this International Standard.