TRACE ELEMENT COMPOSITIONS OF BRINE IMPACTED SOILS AND PRODUCED WATER

Brine impacted soils are remediated by increasing soil permeability with organic matter, and perhaps gypsum, to allow salt to wash out of the soil toward an appropriate receptor (subsurface drainage system, for example). These methods have been shown to be effective in sufficiently reducing salinity to allow re-vegetation. However, re-establishment of a diverse soil ecosystem and plant community can be a lengthy process. The original impact of the salt and the mechanical disruption of the topsoil on subsurface communities during remediation are certainly in part responsible for the long-term nature of the recovery process. However, there may be other factors. Produced water brines may contain potentially phytotoxic components which are not removed from the impacted soil in proportion to sodium chloride.

We have performed an elemental analysis of three produced waters and several brine-impacted soils in Osage County, OK. Soil samples were obtained from four classes of sites: unimpacted by brine, historic brine scars, recent brine spills not remediated and recent brine spills remediated. Analysis showed that certain metals like Sr were elevated in the brine and impacted soil although at concentrations not considered toxic. The only phytotoxic material from produced water found in impacted soils was boron. Soil concentrations were as high as 6 mg/kg, a level known to be phytotoxic.

Future work will determine total and plant available boron in impacted soils as wells as the chemical form existing in the soil. The effect of boron on salt stressed plants will also be investigated.