Selecting Appropriate Forms of Nitrogen Fertilizer to Enhance Soil Arsenic Removal by Pteris Vittata: A New Approach in Phytoremediation

Abstract

Certain plant species have been shown to vigorously accumulate some metals from soil, and thus represent promising and effective remediation alternatives. In order to select the optimum forms of nitrogen (N) fertilizers for the arsenic (As) hyperaccumulator, Pteris vittata L., to maximize As extraction, five forms of N were added individually to different treatments to study the effect of N forms on As uptake of the plants under soil culture in a greenhouse. Although shoot As concentration tended to decrease and As translocation from root to shoot was inhibited, overall As accumulation was greater due to higher biomass when N fertilizer was added. Arsenic accumulation in plants with N fertilization was 100∼300% more than in the plants without N fertilization. There were obvious differences in plant biomass and As accumulation among the N forms, i.e., NH₄HCO₃, (NH₄)₂SO₄, Ca(NO₃)_2, KNO₃, urea. The total As accumulation in the plants grown in As-supplied soil, under different forms of N fertilizer, decreased as NH₄HCO₃>(NH₄)₂SO₄ > urea > Ca(NO₃)₂ >KNO₃>CK. The plants treated with N and As accumulated up to 5.3∼7.97 mg As/pot and removed 3.7∼5.5% As from the soils, compared to approximately 2.3% of As removal in the control. NH₄ ⁺-N was apparently more effective than other N fertilizers in stimulating As removal when soil was supplied with As at initiation. No significant differences in available As were found among different forms of N fertilizer after phytoremediation. It is concluded that NH₄ ⁺-N was the preferable fertilizer for P. vittata to maximize As removal.

KEY WORDS:

• arsenic (As)
• availability
• hyperaccumulator
• nitrogen (N) fertilizer
• nutrient
• phytoremediation
• Pteris vittata
• soil

ACKNOWLEDGEMENTS

This work was supported by the National Science Foundation for Distinguished Young Scholar (Grant 40325003), the National Natural Science Foundation of China (Grant 40232022), and the National High-Tech R&D Program (Grant 2003AA645010).