This study examined the presence and distribution of polycyclic aromatic hydrocarbons (PAH), other petroleum hydrocarbons (PHC) and phosphorus, derived from engine oil, in several Lake Tahoe soils and sediments. The PAH profile in marina sediments, road runoff locations and from water collected immediately after running a 4 stroke engine in a tank had similar signatures, and data collected in this study offered strong evidence that engine emissions were the primary source of these hydrocarbon contaminants in Lake Tahoe soils and sediments. Two PAH's, fluoranthene and pyrene were observed at relatively high concentrations, and were signature compounds in the sediments. In addition, a strong and positive correlation existed for PAH and TPH in road runoff soils and marina sediments indicative of PAH related to vehicle emission.

Phosphorus is an additive to most 4-cycle engine oils and observed at a concentration of 700-1500 mg/L in new and used engine oils. Although this source of phosphorous is potentially significant for nutrient addition to Lake Tahoe, it comprises only a relatively small fraction in the soils and sediments, compared to natural concentrations. The Tahoe soils examined had a total phosphorus content of 500-1000 mg/kg and an available phosphorus content of 20-100 mg/kg. Assuming 0.1% of phosphorus content in the oil and a TPH content of 3000-5000 mg/kg in the highly vehicle affected areas, the phosphorus contribution from engine oil is only 3-5mg/kg.

Alternatively, the hydrocarbon contaminated sediments released more phosphorus into the water under anaerobic conditions and suggests that petroleum hydrocarbons can drive anaerobic processes that eventually will release phosphorus. This is likely an issue in marina sediments, as well as flooded catchment basin sediments.

The three catchment basins examined in the Kings beach area appeared effective in retaining the contaminants. The inlets had high TPH, and PAH concentrations in comparison to the outlets and soil cores collected at different depths in each basin had hydrocarbon concentrations low in the native depths and high in the layer where sediment had accumulated. PAH leaching was evaluated in basin soils and the results indicated that only a small fraction (<0.1%) of PAH compounds would leach.