Emerging investigator series: radium accumulation in carbonate river sediments at oil and gas produced water discharges: implications for beneficial use as disposal management
Emerging investigator series: radium accumulation in carbonate river sediments at oil and gas produced water discharges: implications for beneficial use as disposal management
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DOI：
10.1039/c8em00336j
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发表时间：
2019-02-01
影响因子：
5.5
通讯作者：
Warner, Nathaniel R.
中科院分区：
文献类型：
--
作者：
McDevitt, Bonnie;McLaughlin, Molly;Warner, Nathaniel R.
在美国西部，从油井和气井排出的产出水排入地表水，增加了用于灌溉和牲畜浇水的下游供应。在这里，我们调查了怀俄明州三个邻近支流系统的六个允许排放。在2013-16年度，我们评估了许可排放的镭的活度，以及相关水系沉积物中积累镭的可能性。排泄点沉积物的镭活度约为200-3600Bq kg(-1)，在一个允许排泄点下游30公里处，本底以上的活度为74Bq kg(-1)。在排泄点附近深达30厘米的沉积物中，镭的活度高于本底。X射线衍射和沉积物中有针对性的顺序萃取表明，镭很可能与碳酸盐共沉淀，在较小程度上与硫酸盐矿物共沉淀。PHREEQC模型预测了文石和重晶石中的镭共沉淀，但与下游沉积物的观测结果相比，后者被高估了，因为下游沉积物中碳酸盐占主导地位。质量平衡计算表明，每年有5个排放物排放超过30亿Bq的镭活度(Ra-226+Ra-228)，其中只有5%的年负荷量保留在流出物排放物100米范围内的水系沉积物中；其余95%的镭作为与沉积物有关的和含水的物种运往下游更远的地方。
In the western U.S., produced water from oil and gas wells discharged to surface water augments downstream supplies used for irrigation and livestock watering. Here we investigate six permitted discharges on three neighboring tributary systems in Wyoming. During 2013-16, we evaluated radium activities of the permitted discharges and the potential for radium accumulation in associated stream sediments. Radium activities of the sediments at the points of discharge ranged from approximately 200-3600 Bq kg(-1) with elevated activities above the background of 74 Bq kg(-1) over 30 km downstream of one permitted discharge. Sediment as deep as 30 cm near the point of discharge had radium activities elevated above background. X-ray diffraction and targeted sequential extraction of radium in sediments indicate that radium is likely coprecipitated with carbonate and, to a lesser extent, sulfate minerals. PHREEQC modeling predicts radium coprecipitation with aragonite and barite, but over-estimates the latter compared to observations of downstream sediment, where carbonate predominates. Mass-balance calculations indicate over 3 billion Bq of radium activity (Ra-226 + Ra-228) is discharged each year from five of the discharges, combined, with only 5 percent of the annual load retained in stream sediments within 100 m of the effluent discharges; the remaining 95 percent of the radium is transported farther downstream as sediment-associated and aqueous species.