| ID |
2313 |
| Citation |
Mahmood, F.N., Barbour, S.L., Kennedy, C., Hendry, M.J., 2017. Nitrate release from waste rock dumps in the Elk Valley, British Columbia, Canada. Sci. Total Environ. 605, 915–928. doi:10.1016/j.scitotenv.2017.05.253 |
| Organization |
University of Saskatchewan; SRK Consulting (Canada) Inc. |
| URL |
http://www.sciencedirect.com/science/article/pii/S004896971731361X |
| Abstract/Description or Keywords |
•Blasting at mines is an important but understudied source of nitrate. •NO3 and its stable isotopes were analyzed on waste rock samples and water samples. •NO3 concentrations in fresh blast and aged rock are highly variable. •Field scale leaching efficiency is 80–90%. •In most cases, NO3 flushing from dumps will take several decades. The origin, distribution and leaching of nitrate (NO3_) from coal waste rock dumps in the Elk Valley, British Columbia, Canada were defined using chemical and NO3_ isotope analyses (_15N- and _18O-NO3_) of solids samples of pre- and post-blast waste rock and from thick (up to 180 m) unsaturated waste rock dump profiles constructed between 1982 and 2012 as well as water samples collected from a rock drain located at the base of one dump and effluent from humidity cell (HC) and leach pad (LP) tests on waste rock. _15N- and _18O-NO3_ values and NO3_ concentrations of waste rock and rock drain waters confirmed the source of NO3_ in the waste rock to be explosives and that limited to no denitrification occurs in the dump. The average mass of N released during blasting was estimated to be about 3–6% of the N in the explosives. NO3_ concentrations in the fresh-blast waste rock and recently placed waste rock used for the HC and LP experiments were highly variable, ranging from below detection to 241 mg/kg. The mean and median concentrations of these samples ranged from 10–30 mg/kg. In this range of concentrations, the initial aqueous concentration of fresh-blasted waste rock could range from approximately 200–600 mg NO3_-N/L. Flushing of NO3_ from the HCs, LPs and a deep field profile was simulated using a scale dependent leaching efficiency (f) where f ranged from 5–15% for HCs, to 35–80% for the LPs, to 80–90% for the field profile. Our findings show aqueous phase NO3_ from blasting residuals is present at highly variable initial concentrations in waste rock and the majority of this NO3_ (> 75%) should be flushed by recharging water during displacement of the first stored water volume. Waste rock; Coal; Nitrate; Nitrate isotopes |
| Information Type |
Article |
| Regional Watershed |
Elk River |
| Sub-watershed if known |
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