ISO 19679:2020 pdf free download.Plastics — Determination of aerobic biodegradation of non-floating plastic materials in a seawater/sediment interface — Method by analysis of evolved carbon dioxide.ISO 19679:2020 replaces ISO 19679:2016.
ISO 19679:2020 specifies a test method to determine the degree and rate of aerobic biodegradation of plastic materials when settled on marine sandy sediment at the interface between seawater and the seafloor, by measuring the evolved carbon dioxide (CU2). This test method can also be applied to other solid materials.
This test method is a simulation under laboratory conditions of the habitat found in different seawater/ sediment-areas in the sea, e.g. in a benthic zone where sunlight reaches the ocean floor (photic zone) that, in marine science, is called sublittoral zone
The determination of biodegradation of plastic materials and other solid materials buried in marine sediment is outside the scope of this document.
NOTE Measurement of aerobic biodegradation can also be obtained by monitoring the oxygen consumption, as described in ISO 18830.
The conditions described in this document do not always correspond to the optimum conditions for the maximum degree of biodegradation to occur.
5 Test environment
Incubation shall take place in the dark or in dittuse light in an enclosure which is tree Irom vapours inhibitory to microorganisms and which is maintained at a constant temperature, preferably between 15 °C to 25 °C, but not exceeding 28 °C, to an accuracy of ± 2 °C. Any change in temperature shall be justified and clearly indicated in the test report.
NOTE: Temperatures applied in the test can be different from those found in marine environments.
6.3 Natural seawater/sediment.
Take a sample of a sandy sediment and seawater with a shovel beneath the low-water line into a bucket. Transfer the wet sediment together with seawater into sealed containers for transport and fast deliver it to the laboratory. After delivery, conserve the sediment at low temperature (approximately 4°C) until use. The seawater/sediment sample should be preferably used within 4 weeks after sampling. Record storage time and conditions.
NOTE: Seawater and sediment can also be sampled from large, well-running public marine aquaria.
Measure the TOC, pH and nitrogen content of the sediment and of the natural seawater if used instead of artificial seawater. The carbon content of sediment should be in the range of 0,1 % to 2 %.
A preliminary oxidation can be applied to the sediment in order to decrease the organic matter content and the background respiration. Sediment and seawater are fluxed with air and gently stirred (max. 20 r/min to 30 r/min) in a large container for the desired period of time. Include this pretreatment process in the test report.