Passive Sampling Devices (PSDs) for Bioavailability Screening of Soils Containing Petrochemicals

EPA Grant Number: R827015-01-0
Title: Passive Sampling Devices (PSDs) for Bioavailability Screening of Soils Containing Petrochemicals
Investigators: Roman Lanno, Kathleen Duncan
Institutions: Oklahoma State University, University of Tulsa
EPA Project Officer: Bala Krishnan
Project Period: February 1, 1999 to January 31, 2000 (N/C Ext. to June 3 0, 2000)
Project Amount: $135,687
Research Category: Ecorisk analysis

Description:

The major accomplishments of this quarter were:

1. Selection of a study site
2. Planning of experimental design to suit the study site
3. Initial site reconnaissance and range-finder sampling

The objectives of the proposed research were:

1. To compare the relative efficacy of SPMDs and SPMEs in estimating the availability of petroleum hydrocarbons from soils, ease of deployment, ease of chemical analysis, and cost. PSDs will be deployed in soils representing aged or weathered soils as well as soils that have been recently amended with petroleum product.
2. To calibrate the availability of petroleum hydrocarbons from soils as measured by PSDs to bioavailability as determined by CBRs in soil organisms, microbial acitivity, and numbers of degradative bacteria. Bioavailability (kinetics and toxicity) of petroleum hydrocarbons in soils will be assessed using macro- and microbiological methods and compared to the steady-state residues and kinetics of chemical uptake by the PSDs.
3. Conduct preliminary investigations into the effects of modifying factors of bioavailability of soil contaminants (e.g., soil moisture and nutrient levels (N, P, K), surfactants) as assessed by PSDs and microbial activity.

This quarter was mostly project planning and site reconnaissance. After considering a number of sites, we selected oil spill sites at the Tall Grass Prairie Preserve in Pawhuska, OK, as field study sites. These sites provide us with a concentration gradient of TPH within a small spatial scale (>>3 hectares) and a relatively consistent soil type. A recent pipeline break in February resulted in two areas of contamination, one contaminated to a level of >>31,000 mg/kg TPH, with the other about 10-fold lower at >>4,400 mg/kg TPH. Both these sites were divided in half, with one half receiving fertilizer and organic matter (straw) as a remediation treatment. We were on-site in mid-March for site reconnaissance and sampled extensively in order to have some samples in storage from cooler weather periods prior to any extensive biodegradation of hydrocarbons. We also deployed 4 semipermeable membrane devices (SPMDs) in the contaminated and reference areas at the site for a period of two weeks in a range-finder test to determine if hydrocarbons could be detected in field deployments of SPMDs. After dialysis and cleanup, many individual hydrocarbon peaks were detected in SPMDs deployed at the contaminated site, but not at reference site.

Plans for the current quarter include complete deployment of SPMDs on contaminated and reference sites, collection of soils for laboratory bioassays with earthworms, solid-phase microextraction anaysis (SPME) of hydrocarbons in soilds, measurement of soil gases on site, and characterization of the microbes present in soil samples.