Selenium Concentrations in Pariette Wetland and the Hazard Posed to Aquatic Birds and Fish.

The Pariette Wetlands located in the Uintah Basin of northeastern Utah, is the largest US Bureau of Land Management (BLM) wetland development in Utah. The wetlands contain diverse vegetation and wildlife in an arid climate. Concentrations of selenium (Se) exceed the total maximum daily loads developed to meet the US EPA’s water quality planning and management regulations (40CFR 130). A mass balance of the Se concentrations of water flowing into and out of the wetlands indicates that 80% of the Se is stored or lost within the system. The objective of the study was to estimate the hazard posed by Se in the wetlands to aquatic-dependent birds and fish. Water, sediment, vegetation and benthic macroinvertebrate samples were analyzed for Se by hydride generation atomic absorption spectroscopy at 3 locations in each of 6 ponds distributed from the inlet to the outlet of the wetland complex. Bird eggs and fish collected from the wetlands were also collected and analyzed for total Se. The selenium-specific hazard was determined using 1) a tissue residue approach and 2) a hazard assessment approach based on Se concentrations in five ecosystem components. Whole fish Se concentrations were not indicative of significant reproductive or other health effects in the majority of Pariette Wetlands fish. A small percentage of the total eggs sampled had Se concentrations above common toxicity thresholds, but overall indicate that the Se hazard to biota has decreased since a similar study was performed by the USGS in the late 1980s. Although Se is heterogeneously distributed in the wetlands, the hazard assessment based on Se concentrations in water, sediment, vegetation, and benthic invertebrate samples also suggests a low to moderate Se hazard to biota in the Pariette Wetlands.