Mobility and environmental risk of potentially toxic elements (PTEs) in phosphogypsum-amended saline soils: an integrated soil-leachate assessment.
Mezlini W, Limonti C, Siciliano A, Amor RB
Soil Health
If you've ever amended garden beds with gypsum to break up clay or reduce salt buildup, this research is a direct heads-up: not all gypsum is created equal, and industrial by-product versions can carry hidden heavy metals that accumulate in your soil and the food you grow.
Salty, compacted soils are a growing problem for farmers, and a chalky waste product from fertilizer factories called phosphogypsum seemed like a cheap fix. But when scientists tested it on Tunisian farmland, they found that spreading too much of it allowed toxic metals — including lead and cadmium — to build up in the soil and leach into water below. Mixing it with compost helped reduce this risk, suggesting that if phosphogypsum is used at all, it needs careful dosing and organic matter to keep it safe.
Key Findings
At the highest application rate (40 t/ha), phosphogypsum caused elevated levels of cadmium, chromium, and lead in soil, exceeding acceptable safety thresholds.
Combining phosphogypsum with organic manure reduced the mobility of cadmium, chromium, and lead, demonstrating that manure can partially mitigate heavy metal contamination risk.
Leachate (water draining through the soil) showed decreasing electrical conductivity and pH values within WHO limits, but heavy metal leaching trends varied by element, indicating contamination risk extends below the root zone.
chevron_right Technical Summary
Researchers tested phosphogypsum (a fertilizer industry by-product) as a soil amendment for salt-damaged farmland in Tunisia, finding it can help restore degraded soils but releases toxic heavy metals like cadmium, chromium, and lead at higher doses — a risk that organic manure can partially offset.
Abstract Preview
Phosphogypsum (PG), a by-product of phosphoric acid production, has shown potential as a soil amendment for saline and sodic soils due to its capacity to enhance soil structure, reduce salinity, an...
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