How can I identify contaminated soil?
Written by
Benjamin Miller
Reviewed by
Prof. Martin Thorne, Ph.D.Recognizing contaminated soil requires identifying visible indications and invisible dangers. Unusual colors and dead vegetation indicate the presence of something wrong, but many dangerous toxins emit no such signs. Professional testing is essential for accurately identifying hidden contaminants, such as lead or PFAS chemicals.
Visual Indicators
- Oily sheens or unusual soil colors like blue/green
- Dead vegetation patterns indicating chemical burns
- Unusual odors suggesting petroleum or chemical leaks
Historical Context
- Previous industrial use increases contamination risk
- Old orchards likely contain lead arsenate pesticides
- Pre-1980 buildings risk lead paint contamination
Professional Testing
- Only reliable method for invisible toxins
- Detects contaminants at hazardous concentrations
- Provides certified results for legal documentation
Visible symptoms only show surface problems. Slow plant growth can indicate nutrient deficiencies rather than toxicity. Oil smells indicate the presence of hydrocarbons but not heavy metals. Only professional laboratory testing investigates all hazards, while do-it-yourself solutions have high probabilities of false negatives.
Testing should be directed to the areas with the highest risk. Locations adjacent to manufacturing facilities require testing for industrial chemicals. Areas where older paint has been removed and/or worked on, or where paint may still drip, may also indicate lead. Former orchard areas may have arsenic residues. Additionally, vegetable gardens should be tested before planting edible crops.
Acquire knowledge of contaminant behavior. For example, lead tends to accumulate in the surface soil layers while PFAS compounds migrate to the groundwater. The clay particles in the subsurface soils absorb arsenic. Professional testing considers these behaviors when they collect samples, obtaining samples at different depths in various locations.
Testing frequency matters. Check every 3-5 years in areas of high risk, test immediately after discovering historical land issues. Emergency testing follows chemical spills. Regular monitoring protects against slow contamination buildup.
Correctly interpret results. Compare results to EPA safety levels. Lead levels above 400 ppm require action. Arsenic levels above 20 ppm need mitigation. If a report is complex, seek expertise in interpreting it. Never assume that safety is guaranteed without professional assurance.
Read the full article: 5 Critical Insights into Soil Contamination Testing
