158-14 Dynamics and interactions of nitrate-phosphate with respect to engineered biochar in saturated porous media

Session: Redox-Driven Nutrient and Contaminant Dynamics in Terrestrial Systems

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Abstract:

Nitrogen and phosphorus are commonly available, but essential nutrients for soil health and plant growth. Both nitrogen and phosphorus occur in soil in different forms and are competitive due to their coexistence. Excess nutrient concentrations lead to infiltration due to reduced adsorption onto soil surfaces. In such conditions, soil amendments, such as biochar, play a crucial role in retaining nutrients on their surfaces and make them available for plant uptake. Therefore, this research work aims to investigate the dynamics and interactions of nitrate-phosphate in saturated porous media, as well as the application of raw and engineered biochars in nutrient management. In this research work, equilibrium experiments were conducted for nitrate-phosphate sorption onto raw biochar (BC) and engineered biochars, e.g., iron-modified biochar (Fe-BC) and magnesium-modified biochar (Mg-BC), at varying pH and ionic strengths. Besides, the co-transport and retention of nitrate and phosphate in different biochar-mediated columns were also performed at neutral pH (7 ± 0.1) and two ionic strengths, IS (0 and 10 mM), to mimic natural conditions. Understanding the dynamics and interactions of biochars with respect to the coexistence of nitrate (100 mg/L) and phosphate (10 mg/L) in saturated porous media. Results demonstrated that Mg-BC showed maximum adsorption for nitrate and phosphate at pH 7 ± 0.1 and IS 10 mM, followed by Fe-BC and BC. Anionic effects, electrostatic attraction, and particle aggregation mechanisms drive the adsorption of nitrate-phosphate onto biochar surfaces. Thus, biochar showed potential for nutrient management.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8467

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