Summary

Description

Petroleum Hydrocarbons Based on higher PAH levels in sediment and vegetation, one would expect Pond 1 to pose a greater risk to wildlife than Pond 2. However, in invertebrate samples damselfly and waterboatmen most carcinogenic PAHs were below detection in both ponds. One possible explanation for the lack of PAHs in the invertebrate samples is that sedimentabsorbed PAHs tend to have a limited bioavailability to benthic invertebrates. Aquatic organisms seem to assimilate PAHs more efficiently from water than sediments, thus limited uptake of PAHs from the sediment probably occurs in the interstitial water Neff 1979; Neff 1985. Pond 1 sediment contained lower levels of aromatic hydrocarbons in 1992 compared to 1986 when the pond was receiving refinery wastewater. Total PAHs were below detection in eared grebe eggs and juvenile bluewinged teal liver from Pond 2 and gadwall biles from the reference site at Hutton Refuge. At Pond 1, the high levels of metabolized PAHs in juvenile gadwall biles approximately 600 ug PAHg were noteworthy and should be investigated further. The effects of PAHs on waterfowl populations in the field is largely unknown Peter Albers, U.S. Fish and Wildlife Service, Laurel, Maryland, pers. communication, September 27, 1993. Toxicity can vary with the amount of weathering of the oil and the types and concentrations of PAHs present. Although death from ingestion of oil is not likely, sublethal effects can occur and include: gastrointestinal irritation, pneumonia, damage to red blood cells, immune system suppression, hormonal imbalance, impaired reproduction and reduced growth Albers 1995. Based on PAH concentrations in dietary items such as aquatic invertebrates and pondweed, the risk of acute effects to aquatic birds is low. Highly oiled sediments at the inlet of Pond 1, if disturbed, may pose a risk to aquatic birds. A visible sheen was observed on the waters surface following collection of sediments from the inlet. Aquatic birds contacting the sheen could transfer the oil from their feathers to their eggs King and Le Fever 1979. Oil applied to the egg surface in amounts as small as 1 to 5 ul can cause embryo mortality Leepen 1976, Szaro 1979. Concentrations of four carcinogenic PAHs in sediment and vegetation ranged from below detection to 3.0 ugg. Pond 1 samples tended to contain higher levels of each carcinogenic PAH compared to Pond 2 samples. Trace Elements Selenium was elevated in aquatic invertebrates, bird livers and bird eggs but not in sediment. Selenium concentrations were above threshold levels shown to cause impaired reproduction and embryonic deformities in aquatic birds Lemly 1993. Sediments collected near the inlet of Pond 1 contained elevated concentrations of chromium copper, mercury and zinc.