Scientists discovered that spraying certain organic acids on leafy vegetables like pakchoi can significantly reduce harmful mercury buildup. In tests conducted in mining areas, spraying tartaric acid reduced mercury levels by up to 59%, while humic acid reduced them by 31%. The study found that these sprays work by helping plants block mercury absorption and safely store it away from the parts we eat. This research suggests an affordable, practical way to make vegetables safer to grow in areas with mercury-contaminated soil, which is important for farmers and communities living near mining regions.

The Quick Take

  • What they studied: Whether spraying organic acids on vegetables could reduce the amount of toxic mercury the plants absorb from contaminated soil
  • Who participated: Pakchoi plants (a leafy green vegetable) grown in soil from mining areas known to have mercury contamination; researchers tested different organic acid treatments
  • Key finding: Spraying tartaric acid on leaves reduced total mercury by 59% and the most toxic form (methylmercury) by 45-56%, compared to untreated plants. Humic acid also worked well, reducing mercury by 31-61% depending on the type
  • What it means for you: If you live in or near a mining area with mercury-contaminated soil, this suggests farmers might be able to grow safer vegetables by using simple, affordable foliar sprays. However, this research is still in early stages and would need to be tested more widely before becoming standard farming practice

The Research Details

Researchers conducted two separate experiments growing pakchoi plants in soil collected from actual mining areas. In the first experiment, they tested several different organic acids sprayed directly on plant leaves to see which worked best. In the second experiment, they compared spraying acids on leaves versus adding them to the soil, and studied how the plants’ internal systems changed in response.

The scientists measured how much total mercury and the more dangerous methylmercury form accumulated in the plants. They also examined what was happening inside the plant cells—looking at nutrient absorption, protective compounds the plants made, and how mercury was being stored or blocked from entering the plant.

This approach matters because it tests a practical, low-cost solution that farmers could actually use. Rather than just studying the problem in a lab, the researchers used real contaminated soil from mining areas, making the results more relevant to actual farming situations. By comparing leaf spraying to soil treatment, they identified which method works better and why, providing a foundation for real-world application.

The study was published in a peer-reviewed environmental science journal, indicating it met scientific standards for publication. The researchers used multiple experiments to verify their findings and investigated the actual mechanisms behind why the treatment works. However, the sample size and specific number of plant replicates were not clearly stated in the abstract, and this appears to be preliminary research that would benefit from larger-scale field testing before widespread adoption.

What the Results Show

Spraying tartaric acid on plant leaves was the most effective treatment, reducing total mercury by 59% compared to untreated plants. Humic acid spraying was also effective, reducing mercury by 31% in the initial screening and 56-61% in the more detailed study. Interestingly, when these same acids were added to the soil instead of sprayed on leaves, they actually increased mercury uptake in some cases, suggesting that the leaf-spraying method is specifically what makes the difference.

For the more toxic form of mercury (methylmercury), both spraying methods worked well: tartaric acid reduced it by 45-56% and humic acid by 56-61%. This is important because methylmercury is the form that’s most dangerous to human health.

The researchers discovered that tartaric acid works through three main mechanisms: it helps plants absorb fewer minerals that mercury normally uses to enter the plant, it triggers the plant to make protective compounds that bind to mercury and neutralize it, and it helps the plant store mercury safely in cell walls where it can’t reach the edible parts.

The study found that enhanced antioxidant responses (the plant’s natural defense system) were not the primary reason the treatments worked. This was surprising because scientists often expect plants to fight heavy metal stress through antioxidant activity. Instead, the mercury reduction worked through more direct blocking and binding mechanisms. This finding helps scientists understand that different plants and contaminants may require different protective strategies.

Previous research had shown that foliar (leaf) application of various substances could help reduce heavy metal accumulation in plants, but most studies focused on metals like cadmium and lead rather than mercury. This is one of the first studies to systematically test organic acids specifically for mercury reduction, and it’s among the first to compare tartaric acid for this purpose. The finding that leaf spraying works better than soil application contradicts some assumptions in the field and provides new direction for future research.

The study was conducted in controlled pot experiments rather than large-scale farm fields, so results may differ in real farming conditions with variable weather, soil types, and plant varieties. The specific number of plant samples tested wasn’t clearly stated. The research focused on one type of vegetable (pakchoi), so results may not apply equally to other crops. Additionally, the study didn’t test whether the treated vegetables were actually safe for human consumption or whether the mercury stored in cell walls could be removed during washing or cooking. Long-term effects of repeated applications weren’t examined.

The Bottom Line

Based on this research, there is moderate evidence that spraying tartaric acid or humic acid on vegetables grown in mercury-contaminated soil may reduce mercury levels. However, this should be considered a promising preliminary finding rather than a proven solution. Farmers interested in this approach should: (1) consult with local agricultural experts before implementing, (2) test on a small scale first, (3) continue monitoring soil and plant mercury levels, and (4) await larger-scale field studies before full adoption. This is not a substitute for soil remediation or relocation if contamination is severe.

This research is most relevant to farmers and communities in mining regions or areas with known mercury soil contamination. It may be particularly valuable in developing countries where soil remediation is expensive or unavailable. Home gardeners growing vegetables in potentially contaminated soil might also benefit. However, people living in areas without mercury contamination don’t need to apply these treatments. Those with severe mercury exposure should prioritize soil testing and professional remediation advice over this approach alone.

Based on the study design, the mercury reduction effects appeared within a single growing season. However, realistic expectations would be to see gradual improvement over multiple growing cycles as the treatment is repeated. Long-term benefits and any potential drawbacks from repeated applications are not yet known and would require further study.

Want to Apply This Research?

  • If using this treatment, track: (1) Date and amount of foliar spray application, (2) Plant growth metrics (height, leaf count, harvest weight), (3) Soil mercury test results (before and after season), (4) Vegetable mercury levels if testing is available through local health departments
  • Users could set reminders for regular foliar spray applications during the growing season, log which organic acid product they’re using and at what concentration, and photograph plants to monitor visual health improvements. The app could provide a simple checklist for application timing and weather conditions suitable for spraying.
  • Establish a baseline by testing soil mercury levels before starting treatment. Repeat soil testing annually to track changes. If possible, have harvested vegetables tested for mercury content at the beginning and end of the treatment period. Document any changes in plant health, yield, or appearance. Compare results year-over-year to assess whether repeated applications improve effectiveness.

This research represents preliminary findings from controlled experiments and should not be considered a complete solution for mercury contamination. If you are concerned about mercury in your soil or food supply, consult with local environmental health authorities, agricultural extension services, or certified soil scientists for professional assessment and guidance. Do not rely solely on foliar sprays for mercury contamination—professional soil testing and remediation may be necessary depending on contamination levels. Pregnant women, nursing mothers, and young children should be especially cautious about consuming vegetables from mercury-contaminated areas. This information is for educational purposes and does not replace professional medical or agricultural advice.