کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8863303 1620217 2016 57 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Selenium attenuation via reductive precipitation in unsaturated waste rock as a control on groundwater impacts in the Idaho phosphate patch
ترجمه فارسی عنوان
تضعیف سلنیوم از طریق کاهش بارندگی در سنگ های ضایعات غیر اشباع به عنوان کنترل بر اثرات آب زیرزمینی در پچ آیداهو فسفات
کلمات کلیدی
سلنیوم، انگیختگی طبیعی، جنوب شرقی آیداهو، معدن فسفات، تشکیل فسفریا،
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی
Phosphate mining in southeastern Idaho has historically resulted in the release of dissolved metals and inorganics to groundwater and surface water, primarily due to leachate from waste rock in backfilled pits and overburden storage piles. Selenium (Se) is of particular concern due to its high concentration in leachate and its limited attenuation downgradient of source zones under oxic conditions. Assessments of potential groundwater/surface water impacts from waste rock typically involve laboratory characterization using saturated and unsaturated flow columns packed with waste rock. In this study, we compare the results of saturated and unsaturated column tests with groundwater quality data from the Mountain Fuel, Champ, South and Central Rasmussen Ridge Area (SCRRA), Smoky Canyon, Ballard, Henry, and Enoch Valley Mines, to understand the release and attenuation of Se in different geochemical environments. Column studies and field results demonstrate that the ratio of aqueous Se to aqueous sulfate (Se:SO4 ratio) is a useful metric for understanding Se release and attenuation, where the extent of sulfate reduction is much less than Se reduction. Comparison of dissolved Se and sulfate results suggests that the net leachability of Se from unsaturated waste rock is variable. Overall, Se concentrations in groundwater directly beneath waste rock dumps is not as high as would be predicted from unsaturated columns. Lower Se:SO4 ratios are observed immediately beneath waste rock dumps and backfilled pits relative to areas receiving shallow waste rock runoff. It is hypothesized that Se released in the oxic upper portions of the waste rock is subsequently attenuated via reductive precipitation at depth in unsaturated, low-oxygen portions of the waste rock. This highlights an important mechanism by which Se may be naturally attenuated within waste rock piles prior to discharge to groundwater and surface water. These results have important implications for mining practices in the region. A better understanding of Se dynamics can help drive waste rock management during active mining and capping/water management options during post-mining reclamation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Geochemistry - Volume 74, November 2016, Pages 176-193
نویسندگان
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