Interaction between co-solvents and algae in the residue dynamics of fenitrothion

Fresh and estuarine water algae maintained in laboratory microcosms simulating river-lake/estuary-bay systems were exposed to 14C-fenitrothion formulated with Atlox and tank mixed with Aerotex or Dowanol (11.5:1.5:1.5 w/v/v). Generally, the tank mix co-solvents determined the amount of uptake and the array of derivatives formed by the algae. Typically, exposed to an Aerotex mix the ratio of ethyl acetate extractable (NP) fraction: ethyl acetate unextractable (P) fraction was as 3.5:1.0, exposed to a Dowanol mix the ratio was as 1.5:1.0. Within any comparable time period, fresh water algae turned over more of the 14C-ring of fenitrothion than the estuarine genera. Turn-over was enhanced when Aerotex was the tank mix co-solvent.