The NMSU Agricultural Science Center at Farmington (NMSU-ASC) is involved in a long-term research project to examine the phytoremediation ability of hybrid poplars at a petroleum-contaminated site. The project, located at an abandoned oil refinery in northwestern New Mexico, was initiated in early 2010 at the invitation of two local environmental remediation firms tasked with cleaning up the site. The goal of the project is to clean up the soil and groundwater via the documented phytoremediation ability of poplars, plus establish an underground root barrier that will help prevent contaminant movement from the site.
The refinery, which was in operation from 1973 to 1991, was selected for the current study due to the high levels of soil and groundwater contamination with free product floating on the water table. Analysis of groundwater shows levels of total dissolved solids (TDS) exceeding 4,500 mg/L and concentrations of methyl tertiary butyl ether (MTBE) near 55 µg/L. Levels of Gasoline Range Organics (GRO C6-C10) are ~0.11 mg/L. Since 2010, nearly 800 trees have been planted, in four phases. Drip irrigation is supplied from an on-site well ~1,500 feet deep, although the water is heavily saline (TDS 1,000 to 2,700 mg/L).
Many of the trees are surviving and growing at the site. Current observations suggest hybrid poplar, native cottonwood, and the xeric species four-wing saltbush (Atriplex canescens) are capable of adequate initial growth on the petroleum-contaminated site when supplied with sufficient irrigation for initial root establishment. Since there are many similar contaminated sites in the arid western U.S. where trees could theoretically be used for such purposes in combination with compromised irrigation water, long-term results from this project may be useful in helping to develop environmental remediation strategies for the region.