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
The major accomplishments of this quarter were:
Research this quarter mostly involved the deployment of SPMDs at the spill sites on the Tallgrass Prairie preserve. SPMDs were deployed in hydrocarbon-contaminated spill sites and in various control areas. The recent spill area (February 1999) is comprised of two lobes (north and south), which differ about 10-fold in TPH (~31,000 and ~4,400 mg/kg, respectively). Each lobe was physically divided in half by a polyethylene barrier, with the upslope portion receiving a treatment of straw that was tilled in, while the downslope halves of each lobe were treated with nutrients (C:N:P:K 100:1:0.3:0.3,N as ammonium nitrate, P as superphosphate, K as potassium oxide). An area of prairie without hydrocarbon contamination was tilled with straw to serve as a control area for the effects of tilling and straw addition. Other reference areas comprising prairie soil without tilling and the addition of straw were located upslope of the north lobe of the spill area. Four SPMDs were deployed in each of the prairie and tilled reference areas and in the two sections of the north lobe of the spill. Three SPMDs were placed in each half of the south lobe of contamination, for a total of 22 SPMDs. SPMDs were deployed by simply digging a hole with a shovel, breaking up the soil clod into smaller fragments and then placing the SPMD flat in the bottom of the hole. The SPMDs were placed at a depth of approximately 15 cm and gently covered with the soil that was removed in the preparation of the hole. The soil was gently compressed into the hole in order to avoid possible damage to the SPMDs. An orange strip of flagging tape long enough to extend above the soil surface once the SPMD was buried was attached to each SPMD. A one-foot square area around the hole for each SPMD was marked with four orange flags for ease of location. The SPMDs were left in place for a period of 21 days.
Soil was also collected for microbial enumeration with a sterile polyethylene centrifuge tube (50-mL size, approximately 5-cm diameter by 18 cm long) pushed into the soil at a depth of 1-8 cm. Four samples were taken per sampling location, all within a one-foot radius of a SPMD, and collected into a sterile Whirlpac™ bag for transport back to the laboratory. Soil was stored in the Whirlpac™ bag at 4°C for no more than three days before being composited by thorough mixing in a sterile glass beaker. A subsample was withdrawn for microbial enumeration and for estimation of soil moisture. Soil moisture was determined by gravimetric measurement of two 10-g samples (wet weight) after oven drying.
Plans for the current quarter include the continued microbial assessment of soils, comprehensive measurement of TPH, and the development and validation of the solid-phase microextraction (SPME) technique for the determination of bioavailable hydrocarbons.