Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States.
Environ Sci Technol. 2013 Oct 15;47(20):11849-57. doi: 10.1021/es402165b. Epub 2013 Oct 2.
The safe disposal of liquid wastes associated with oil and gas production in the United States is a major challenge given their large volumes and typically high levels of contaminants. In Pennsylvania, oil and gas wastewater is sometimes treated at brine treatment facilities and discharged to local streams. This study examined the water quality and isotopic compositions of discharged effluents, surface waters, and stream sediments associated with a treatment facility site in western Pennsylvania. The elevated levels of chloride and bromide, combined with the strontium, radium, oxygen, and hydrogen isotopic compositions of the effluents reflect the composition of Marcellus Shale produced waters. The discharge of the effluent from the treatment facility increased downstream concentrations of chloride and bromide above background levels. Barium and radium were substantially (>90%) reduced in the treated effluents compared to concentrations in Marcellus Shale produced waters. Nonetheless, (226)Ra levels in stream sediments (544-8759 Bq/kg) at the point of discharge were ~200 times greater than upstream and background sediments (22-44 Bq/kg) and above radioactive waste disposal threshold regulations, posing potential environmental risks of radium bioaccumulation in localized areas of shale gas wastewater disposal.
美国与油气生产相关的液态废物的安全处理是一个重大挑战，因为这些液体废物的数量大，且通常含有很高水平的污染物。在宾夕法尼亚州，有时会在盐水处理设施对油气废水进行处理，然后排放到当地的溪流中。本研究调查了与宾夕法尼亚州西部一个处理设施现场相关的排放废水、地表水和溪流沉积物的水质和同位素组成。废水中的氯和溴含量较高，加上其锶、镭、氧和氢的同位素组成，反映了马塞勒斯页岩采出水的组成。废水从处理设施排放后，下游的氯和溴浓度高于背景水平。与马塞勒斯页岩采出水相比，处理后的废水中钡和镭的含量大幅（>90%）降低。然而，排放口处溪流沉积物中的（226）Ra 水平（544-8759 Bq/kg）是上游和背景沉积物（22-44 Bq/kg）的约 200 倍，高于放射性废物处置的阈值规定，这在页岩气废水处置的局部地区可能造成镭生物累积的环境风险。
