Remediation of Soils Contaminated by Fluoride Using a Fermentation Product of Seaweed (Eucheuma cottonii)

Abstract

is study investigated the e cacy of fermented seaweed (Eucheuma cottonii) on the remediation of uoride-contaminated soil. e soil was amended with either 1.25, 3.0, or 5.0% (w/w) fermented seaweed (FSW), parallel with the controls (0%). e amendment improved the physicochemical properties of the soil particularly pH regulated from strong alkaline (9.3) to neutral (7.0) which is essential for germination, crop growth, and yield. e amount of water soluble- uoride (Ws-F) dropped from 81.7 ± 3.1 mg/kg to 42.7 ± 2.4, 33.7 ± 1.2, 19.6 ± 0.9, and 12 ± 1.3 mg/kg following 0, 1.25, 3, and 5% amendment dosage, re spectively. Most of the Ws-F was converted into exchangeable uoride (Ex-F) and to uoride-bound to iron and manganese (Fe/ Mn-F). Furthermore, the amendment also enhanced microbial mass and diversity in the soil. e FSW contains organic acids which participate in ionic bonding with the multivalent cations in the soil. e formed compound participates in ion exchange with clay or with anionic adsorption to positively charged clay sites at the edges. is interaction is further essential for enhancing the uoride holding capacity of the soil. e use of seaweed reduced the bioavailability of uoride in the agricultural soils and had positive e ects on promoting soil fertility. However, further studies to observe its e ects on crop performance is of signi cance.