Evaluating promulgated refinery effluent standards using artificial streams.

Two-week tests on an Artificial Refinery MIxture (ARM) were conducted on periphyton communities on glass slides in laboratory streams. ARM components, which are present in "typical" refinery effluents, approximate maximum allowable concentrations as promulgated by the 1977 U.S. Environmental Protection Agency (USEPA) guidelines for refinery effluents. ARM concentrations tested ranged from approximately 0.25 to 5 times full strength. The nontaxonomic structural parameters--ash-free dry weight, chlorophyll a, and ATP--indicated that ARM concentrations of 1 to 5X stimulated periphyton colonization rates. ARM concentrations of 0.25 to 5X caused a shift in dominant periphytic algae from diatoms in reference streams to green algae in dosed streams; this resulted in higher pH levels in reference streams, apparently related to photosynthetic activity. Changes in nontaxonomic structural parameters of slides precolonized with periphyton were not sensitive water quality indicators. Dry weight was not a useful biomass indicator due to high levels of suspended solids in ARM. The promulgated 1977 guidelines may be adequate to maintain nontaxonomic structural integrity of periphyton communities, while the 1983 guidelines appear to be adequate to maintain taxonomic integrity.