W10 PM Environmental Interactions of Marine Antifoulants
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 341-342

(GAR-1118-467505) Assessing the fate and transport of Irgarol 1051 and its interactions with biological endpoints in near-coastal environments.

Gardinali, Piero^{1, 2}, Maxey, Charles ², Zamora, Ingrid³, Jochem, Frank ⁴, ¹ Florida International University, Southeast Environmantal Research Center (SERC), Miami, FL, United States² Florida International University, Department of Chemistry & Biochemistry, Miami, FL, United States³ Florida International University, Department of Environmental Studies, Miami, FL, United States⁴ Florida International University, Department of Biological Sciences, Marine Biology Program, Miami, FL, United States

ABSTRACT- Irgarol 1051, a triazine-based herbicide, has been used as an antifouling boosting agent in copper based paints since the early 90′s. Although it was introduced as an alternative to TBT and it was predicted to easily dissipate under environmental conditions its occurrence has been widely documented worldwide. Environmental concentrations of Irgarol are usually restricted to the low part per trillion levels in open coastal waters but boat storage areas with large numbers of wet slips and restricted water movement have shown concentrations of the herbicide in the low part per billion range. Our monitoring program within US coastal waters started in 1994 and to date we have analyzed 930 surface water samples including a vast variety of coastal systems like marinas, ports, open bay areas, rivers, and offshore reef locations. As an example, the 90th percentile of the concentrations observed in Florida waters between 1998 and 2002 was 57.6 ng/L. To date the number of locations where concentrations of Irgarol consistently exceed the 100-136 ng/L reported to reversibly affect marine algal species is restricted to about 2 % of the sites sampled and inevitably correspond to large marinas. Accumulation of Irgarol in submerged vegetation is limited with BCF′s ranging from 500 to 1600 and negligible accumulation on sedimentary phases. Photolysis is the prevalent mechanism to degrade Irgarol 1051 under natural conditions. The average half-life of Irgarol 1051 in natural fresh- and saltwater was calculated to be between 6 to 10 days. M1 (the major metabolite) however is more resistant to sunlight degradation. Partition coefficients (Kow) calculated for Irgarol, M1 and other less common degradation products showed good agreement with the environmental assessment data. Both Irgarol and M1 are commonly present in water samples but only the parent compound has limited ability to accumulate in sediment and plant material. Study of the effects of Irgarol to individual species of algae present in marinas along the Florida Keys showed effects only at concentrations in excess of 800 ng/L. The data collected in 7 years clearly indicate that Irgarol is ubiquitous in marinas and enclosed bay areas but is hardly detected in open marine waters. However, concentrations in excess of those reported to produce effects are exceptions rater than the norm.

Key words: Irgarol 1051, Occurrence and fate, accumulation and effects, submerged vegetation and phytoplankton