Water-level variations and their effects on tree growth and mortality and on the biogeochemical system at the phytoremediation demonstration site in Fort Worth, Texas, 1996-2003

In Situ Remediation of a TCE-Contaminated Aquifer Using a Short Rotation Woody Crop Groundwater Treatment System

“…The follow-on studies conducted either to directly support or enhance the information collected during the 3-year demonstration, or conducted as supplemental research are summarized in the following discussions. (Braun et al, 2004).…”

“…Thus, a lesson learned may be the connection between tree growth/tree mortality and the lack of water. Per Braun et al (2004), cottonwood tree mortality rates approached 90% where groundwater levels were between 12 and 13 ft bls and a relatively constant 25% where groundwater levels were less than 10 ft bls. This may have been caused by overplanting.…”

“…Beavers at the demonstration site have been an annual concern since 1996. Braun et al, 2004 reported that up through the start of 2003 49% of the trees in the caliper plantation were either stunted by beaver activity (40%) or altered by human activities (9%).…”

“…Based on modeling, the technology was supposed to achieve full canopy closure in 12 years and beyond, which would result in maximum transpiration (resulting in a predicted drawdown of 12-25 cm at center of drawdown cone). However, Braun et al (2004) have graphically shown that, as of January 2003, mortality rates in both plantations have been significant-189 (43%) of trees in the whip plantation had died, and 111 (26%) of the trees in the caliper trees have either died, been stunted by beaver activity, or altered by human activity.…”

“…Although Eberts et al (2005) focused on VOC in wells along the centerline of the plume, VOC monitoring for the entire set of wells monitored during the demonstration was continued through the sixth growing season (2002). The results for TCE and cDCE (Table 10 and Table 11, respectively) are included in Braun et al (2004), a report that investigated biogeochemical parameters and water-level variations at the demonstration site and discusses how the water-level variations affected tree growth and mortality. (Clinton et al, 2004) This July 2000 study examined the relative uptake of surface water versus groundwater by mature trees for determining the relative contribution of groundwater to plant transpirational water use.…”