Enrichment of elements in detritus from a constructed wetland and consequent toxicity to Hyalella azteca.

In a pilot constructed wetland treatment system specifically designed to treat constituents of flue gas desulfurization wastewater, detritus adsorbs significantly high concentrations of Hg, Se, and As. Results of this research indicate that Hg, Se, and As were enriched in detritus from Schoenoplectus californicus and Typha angustifolia collected from the constructed wetland by factors up to 4600, 26,300, and 15,600, respectively. As an important food source for many organisms, element enrichment makes the detritus an even greater source of contaminants to the food web. Results demonstrate that the natural decomposition of plants in this constructed wetland treatment system produces detritus enriched with Hg, Se, and As at levels potentially hazardous to aquatic organisms. To completely assess ecological risks associated with the use of constructed wetland treatment systems, contaminant enrichment, bioavailability, and toxicity in detritus must be considered.