Compost Tea and PFAS Uptake in Sunflowers

ISEF Category: Environmental Engineering

Subcategory: Bioremediation  ·  Difficulty: Advanced  ·  Setup: School Lab  ·  Time: Full Year

The Hook

PFAS are called forever chemicals because they stick around for a very long time. That makes them a nightmare in water, soil, and food webs. You can test whether friendly root microbes help sunflowers pull more or less of these compounds from their growth water. That connects plant biology, pollution cleanup, and real environmental data.

What Is It?

This project asks whether the microbes around a plant’s roots change how much PFAS the plant absorbs. The root zone, or rhizosphere, is like a busy neighborhood around the roots. Microbes there can change nutrient flow, root chemistry, and how chemicals move through the system.

Compost tea is a liquid made from compost that can add microbes to that root zone. In this project, you would compare sunflowers grown with and without that microbial boost in PFAS-spiked hydroponic media. Hydroponic media means the plants grow in water or a water-based solution instead of soil. The main question is whether the microbial community changes PFAS uptake, movement, or retention in the system.

Why This Is a Good Topic

This is a strong science fair topic because you can test a real environmental problem with a clear comparison. You have a measurable outcome, PFAS in water or plant tissue, and a clear treatment, compost tea inoculation. The project can teach you experimental design, contamination control, and how to interpret messy environmental data. It also connects to water safety, plant-based cleanup, and soil microbiology.

Research Questions

• How does compost tea inoculation change PFAS concentration in the hydroponic water over time?
• What is the effect of compost tea on PFAS accumulation in sunflower roots versus shoots?
• Does the presence of compost tea change the rate at which PFAS leaves the growth solution?
• To what extent does compost tea treatment change sunflower biomass under PFAS exposure?
• Which PFAS chain lengths show the largest difference in uptake between treated and untreated plants?
• How does the timing of compost tea inoculation affect PFAS uptake by sunflowers?

Basic Materials

• Sunflower seeds with similar size and age.
• Clean hydroponic containers with lids or covers.
• Inert hydroponic media such as clay pebbles or rockwool.
• Standard hydroponic nutrient solution.
• Compost tea made from finished compost.
• PFAS-spiked water prepared by a qualified lab or supervisor.
• Gloves rated for chemical handling.
• Labeling tape and waterproof marker.
• Digital balance with gram resolution.
• Ruler or measuring tape for plant growth.
• Camera or smartphone for growth photos.
• Mail-in PFAS water test kit from a certified analytical lab.
• Distilled water for rinsing and control setup.
• Notebook or spreadsheet for data logging.

Advanced Materials

• Access to a certified PFAS analytical lab for liquid chromatography tandem mass spectrometry.
• Sample bottles certified for trace PFAS work.
• Glassware or PFAS-free containers for collection and storage.
• Filtration setup for water samples.
• Freeze-dryer or drying oven for plant tissue prep, if the lab allows it.
• Grinder or homogenizer for plant tissue prep.
• Ion chromatography or total organic fluorine access, if available.
• Sterile hood or clean bench for contamination control.
• Micropipettes with PFAS-free tips and reagents.
• Microbial plating supplies or DNA extraction kit for rhizosphere checks.
• Analytical balance with milligram resolution.
• Statistical software for mixed-effects or multivariate analysis.

Software & Tools

• Google Sheets: Organizes treatment groups, growth measurements, and PFAS results in one place.
• R: Runs statistical tests, plots uptake trends, and compares treatment groups.
• ImageJ: Measures plant size from photos and tracks growth changes over time.
• JASP: Offers point-and-click statistics for students who want a simpler analysis workflow.
• GraphPad Prism: Creates clean graphs and helps compare means and error bars if your school has access.

Experiment Steps

1. Define the exact PFAS question you want to answer, such as uptake, retention, or growth impact.
2. Choose one sunflower variety, one compost tea treatment, and one no-tea control so your comparison stays clean.
3. Plan how you will prevent PFAS contamination from cups, gloves, labels, and rinse water.
4. Build a sampling plan that tracks water, roots, and shoots separately so you can see where the PFAS goes.
5. Decide how you will confirm the treatment really changed the rhizosphere, such as growth differences, microbial counts, or a separate microbial check.
6. Set up the analysis before you start, including blanks, replicates, and the statistical test you will use.

Common Pitfalls

• Using ordinary plastic containers or tubing that may add trace PFAS and ruin the clean comparison.
• Treating compost tea as one fixed material, even though its microbial makeup can vary a lot from batch to batch.
• Mixing up root exposure and leaf exposure, which makes it hard to tell where PFAS entered the plant.
• Relying on one plant per group, which hides natural variation and weakens your results.
• Sending water samples without a strict contamination plan, which can make the mail-in test read background contamination instead of your treatment effect.

What Makes This Competitive

A stronger project will separate simple plant growth effects from true PFAS movement. You can make it stand out by using enough replicates, tracking several sample types, and pairing chemical data with plant health data. A deeper analysis, such as comparing different PFAS chain lengths or linking uptake to microbial changes, adds real scientific value. Careful contamination control matters a lot here, because PFAS studies live or die on clean methods.

Project Variations

• Test whether compost tea changes PFAS uptake in lettuce instead of sunflowers.
• Compare two microbial inoculants, such as compost tea and a commercial beneficial microbe mix, for their effect on PFAS movement.
• Measure whether PFAS exposure changes root architecture, then relate root shape to uptake patterns.

Learn More

• PubMed: Search review articles on PFAS uptake by plants, rhizosphere interactions, and phytoremediation.
• NOAA National Ocean Service: Read background pages on persistent pollutants and how they move through water systems.
• USGS PFAS Information: Find plain-language summaries and technical reports on PFAS in water and environmental samples.
• NIH PubChem: Look up PFAS structures and properties to compare chain length, solubility, and persistence.
• MIT OpenCourseWare: Search environmental engineering and analytical chemistry course materials for sampling, contamination control, and statistics.
• Environmental Science & Technology: Search recent peer-reviewed articles on PFAS transport, plant uptake, and remediation.