title: Indirect estimation of degradation time for zinc pyrithione and copper pyrithione in seawater.
abstract: The degradability of two antifouling biocides: zinc pyrithione (ZPT) and copper pyrithione (CPT) in seawater was examined. Reduction in toxicity due to degradation was monitored over two days using a bioassay with natural assemblages of coastal marine bacteria from Roskilde Fjord, Denmark. To investigate photo-degradation of the compounds, bacteria were exposed to sterile ZPT- and CPT-dilution that had either been exposed to sunlight or darkness. Bio-degradation was examined by diluting ZPT and CPT in sterile seawater or natural seawater. Photo-degradation half-life for ZPT was estimated to be 8.3+/-0.9 min and for CPT to 7.1+/-0.2 min. Total and microbial degradation in combination with photo-degradation did not further shorten the degradation time, suggesting no bio-degradation. Bio-degradation without the influence of sunlight was also negligible over the time-period investigated. ZPT and CPT are therefore suggested to persist in the marine environment where the influence of the light is limited.
authors.affiliation: National Environmental Research Institute, NERI, Fredriksborgues 399, 4000 Roskilde, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Maraldo
authors.forename: I
authors.initials: I
authors.lastname: Dahllöf
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003718:Denmark; D009942:Organometallic Compounds / Q000378:metabolism* / Q000493:pharmacokinetics / Q000633:toxicity; D010782:Photolysis; D011725:Pyridines / Q000378:metabolism* / Q000493:pharmacokinetics / Q000633:toxicity; D012623:Seawater / Q000032:analysis* / Q000382:microbiology; D013997:Time Factors; D023382:Toxicity Tests, Acute
chemical_list: D009942:Organometallic Compounds; D011725:Pyridines; C487833:copper pyrithione; C010423:pyrithione zinc