Abstract

Leaves from Spartina alterniflora Loisee (smooth cordgrass) plants grown with their roots in solutions containing ¹⁴C ring-labeled atrazine were converted to detritus in model ecosystems that simulated the salt marsh environment. Percentages of radioactivity in chloroform-soluble, water-soluble, and insoluble materials in the leaves were 55, 38, and 7, respectively. Twenty days later these values for detritus were 9, 78, and 13, respectively. Thus, there was a decline in the percentage of radioactivity in the chloroform fraction which contains atrazine and nontoxic metabolites and a concurrent increase in the water-soluble fraction that contains only nontoxic metabolites.

An important detritivore in the salt marsh, the mud fiddler crab, when fed detritus labeled with atrazine further decreased the percentage of the chloroform-soluble atrazine or atrazine metabolites. Radioactivity originally present in either atrazine or atrazine metabolites fed to mud fiddler crabs was concentrated in the water-soluble extract from the crabs, suggesting that either selective absorption through the gut or metabolism of the chloroform-soluble form(s) to water-soluble material by the fiddler crabs or the crabs' enteric flora. Atrazine and atrazine metabolite concentrations were reduced from lower (detritus) to higher trophic levels (mud fiddler crabs) in the simulated salt marsh ecosystem.

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