Behaviour of EDTA in marine microcosms

Laboratory-scale microcosm tests were carried out in sea water with and without sediment to investigate the importance of ultraviolet (UV) light and microbes in the temperature-dependent degradation of metal complexes of ethylenediaminetetraacetic acid (EDTA). After 17 weeks, 44% and 48% of the original EDTA (initial concentration 385 microg/L) were converted at 10 degrees C and 22 degrees C, respectively. The degradation was more influenced by UV light than by sediment microbes, although the latter were very important. At both temperatures, absorption of EDTA to the sediment phase reached a maximum in the initial stage of the experiments (<4 weeks): at 10 degrees C about 4% and at 22 degrees C about 7% of the original EDTA.