Variations in phytoremediation performance with diesel-contaminated soil

The potential for phytoremediation of high concentrations of petroleum hydr ocarbons is poorly understood. This study examines variations in phytoremed iation performance for a soil contaminated with diesel at 6400 mg TPH kg(1) dry mixture. Experiments on diesel-contaminated soil were conducted in cup s using 200 g of soil, and in columns using 4,000 g. Root development and T PH levels were measured in both experiments. In addition, CO2 soil gas conc entrations were measured in the column experiments. The results show that r yegrass enhanced the loss of TPH over controls, and that this benefit only became evident after full root establishment. A comparison of the two exper iments shows that rooting intensity (mg root kg(1) soil) is the key factor leading to higher TPH loss rates in the smaller containers. No dear differe nce in TPH loss occurred at 100 and 260 mm depths. Soil gas CO2 did not cor relate well with TPH loss rates. The research concludes that an understandi ng of root development is crucial to evaluating the potential for ryegrass phytoremediation.