Factors influencing As(V) stabilization in the mine soils amended with iron-rich materials

• Published in: Environmental science and pollution research international 2018-09, Vol.25 (27), p.26757-26765
• Main Authors: Kim, Mijin, Kim, Juhee, Kim, Minhee, Kim, Yong-Seong, Nam, Seung Mo, Moon, Deok Hyun, Hyun, Seunghun
• Format: Article
• Language: English
• Subjects: Abandoned mines; Aquatic Pollution; Arsenic - chemistry; Atmospheric Protection/Air Quality Control/Air Pollution; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Industrial Waste; Iron; Mining; Organic chemistry; Protection and Restoration of the Environment; Rate constants; Reduction; Slag; Sludge; Soil - chemistry; Soil contamination; Soil Pollutants - chemistry; Soil stability; Soil stabilization; Stability analysis; Steel; Steel making; Time dependence; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-017-0044-9

Chemical stability of As(V) in amended mine-impacted soils was assessed according to functions of incubation period (0, 1, 2, 4, and 6 months), amendment dose (2.5 and 5%), and application timing (0 and 3rd month). Six soils contaminated with 26–209 mg kg −1 of As(V) were collected from two abandoned mine sites and were treated with two alkaline iron-rich materials (mine discharge sludge (MS) and steel-making slag (SS)). Seventeen to 23% of As(V) in soils was labile. After each designated time, As(V) stability was assessed by the labile fractions determined with sequential extraction procedures (F1–F5). Over 6 months, a reduction (26.9–70.4%) of the two labile fractions (F1 and F2) and a quantitative increase (7.4–29.9%) of As(V) in F3 were observed ( r 2  = 0.956). Two recalcitrant fractions (F4 and F5) remained unchanged. Temporal change of As(V) stability in a sample was well described by the two-domain model ( k fast , k slow , and F fast ). The stabilization (%) correlated well with the fast-stabilizing domain (F fast ), clay content (%), and Fe oxide content (mg kg −1 ), but correlated poorly with kinetic rate constants ( k fast and k slow ). Until the 3rd month, the 2.5%-MS amended sample resulted in lower As(V) stabilization (25–40%) compared to the 5% sample (50–60%). However, the second 2.5% MS addition on the 2.5% sample upon the lapse of the 3rd month led to a substantial reduction (up to 38%) of labile As(V) fraction in the following 4th and 6th months. As a result, an additional 15–25% of As(V) stability was obtained when splitting the amendment dose into 3-month intervals. In conclusion, the As(V) stabilization by Fe-rich amendment is time-dependent and its efficacy can be improved by optimizing the amendment dose and its timing.