REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION ACTION TEAM
FIELD STUDY PROTOCOL
May 29, 1998

TITLE: PHYTOREMEDIATION OF PETROLEUM HYDROCARBONS IN SOIL
PURPOSE: Determine efficacy of agricultural and non-crop plants for degradation of petroleum hydrocarbons in soil at multiple locations and under varied climatic conditions.
LOCATIONS: Approximately 12 sites in North America
PLOT SIZE: 20' x 20' minimum
REPLICATIONS: 4
STATISTICAL DESIGN: Randomized complete block. (Place plots based on presence of TPHs in site characterization. For soil and plant samples, take 4 random sample cores per plot and make a composite sample.)
TREATMENTS:
  • Local optimized treatment: grass, mix of species, including trees
  • Unplanted control (kept weed-free; in descending order of preference use (1) RoundUp or equivalent post-emergent, (2) hand-picking of weeds, (3) tilling, (4) pre-emergent herbicide).
  • Mixture of
    • rye 10 to 15% (annual or perennial),
    • legume 20 to 25% (alfalfa, clover, birds-foot trefoil), and
    • fescue 60 to 70% (varieties chosen for local conditions).
SOIL SAMPLING:

Take soil samples in each sampling location at the following times:

T=I: Initial site characterization (samples taken 0" to 6" after tilling)
T=0: Before planting, after seed bed prep (samples taken at 0" to 6" and 6" to 18")

T=1:

6 months after planting, or end of first growing season (samples taken at 0" to 6" only)

T=2:

18 months after planting, or end of second growing season (samples taken at 0" to 6" only)

T=3:

30 months after planting, or end of third growing season (samples taken at 0" to 6" and 6" to 18")

Use 1" diameter sampler (hand sampling, GEOPROBE or equivalent). Preserve each sample in a clean plastic sample liner. See Appendix A: Soil Sampling, Storage and Shipping Method.

PLANT SAMPLING:

Take plant shoot samples at time 3 (30 months) for hydrocarbon analysis.

See Appendix B: Vegetation Sampling, Storage and Shipping Method.

SAMPLE ANALYSIS:

Send composite soil samples for analysis of:

  1. Agronomic conditions: pH, salinity, available nutrients, soil analysis (texture, organic matter, EC, CEC, soil type). (The analyses should be tailored to the region.)
  2. Contaminant concentrations: PAHs using EPA method with GC, TPH
  3. Biomarkers (times 0, 1, 2, and 3)
  4. Microbial analysis (times 0 and 3)

PLANT ASSESSMENTS:

Evaluate plant characteristics at 6 months, 18 months, and 30 months:

  • Percent cover
  • Shoot height
  • Rooting characteristics (root depth and density)
GROWING CONDITIONS: Conduct seed bed preparation, planting technique, planting rate, and irrigation in site-specific manner to establish good stand growth. Record procedures. Fertilize and lime based on need from initial soil sampling. Record rainfall, irrigation, and average daily temperature (available from local airport) throughout growing season.

Sampling Event Matrix Analysis Purpose
T=I soil PAH, agro determine variability,
agronomic amendments
0 soil PAH, TPH, micro, bio establish baseline
1 soil PAH, TPH, agro, bio, plant assessment assess first season results
2 soil PAH, TPH, agro, bio, plant assessment assess second season results
3 soil, plant PAH, TPH, agro, micro, bio, plant assessment assess third season results,
assess plant uptake, if any