Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO 80523, USA.
Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO 80523, USA; Department of Chemistry, Colorado State University, 1872 Campus Delivery, Fort Collins, CO 80523, USA; Department of Soil and Crop Sciences, Colorado State University, 1170 Campus Delivery, Fort Collins, CO 80523, USA.
Sci Total Environ. 2020 Apr 15;713:136607. doi: 10.1016/j.scitotenv.2020.136607. Epub 2020 Jan 11.
Produced water (PW) is the largest waste stream associated with oil and gas extraction and contains organics, salts, metals and radioactive materials. In the United States, west of the 98th meridian, the National Pollutant Discharge Elimination System exemption allows for release of PW to surface waters for agricultural beneficial reuse if it is "of good enough quality". Due to the complex and variable composition of PW, the downstream impacts of these releases are not fully understood. In this study, a detailed chemical analysis was conducted on a stream composed of PW released for agricultural beneficial reuse. Over 50 geogenic and anthropogenic organic chemicals not specified in the effluent limits were detected at the discharge including hydrocarbons, halogenated compounds, and surfactants. Most were removed within 15 km of the discharge due to volatilization, biodegradation, and sorption to sediment. Inorganics detected at the discharge were within regulatory effluent limits. While some inorganic species (i.e., strontium, barium and radium) decreased in concentration downstream due to co-precipitation, concentrations of many inorganic species including sodium, sulfate and boron increased due to water evaporation. Consequently, downstream water quality changes need to be considered to adequately evaluate the potential impact of discharged PW. Regulatory health thresholds for humans, livestock, and aquatic species for most chemical species present at the discharge are still lacking. As a result, toxicity tests are necessary to determine the potential health impacts to downstream users.
生产水（PW）是与石油和天然气开采相关的最大废水，含有有机物、盐类、金属和放射性物质。在美国，在第 98 子午线以西，国家污染物排放消除系统豁免允许将 PW 释放到地表水中进行农业有益再利用，如果 PW 的“质量足够好”。由于 PW 的复杂和可变组成，这些释放物的下游影响尚未完全了解。在这项研究中，对由用于农业有益再利用的 PW 释放的溪流进行了详细的化学分析。在排放口检测到 50 多种未在排放标准中规定的地球成因和人为有机化学品，包括碳氢化合物、卤代化合物和表面活性剂。由于挥发、生物降解和沉积物吸附，大多数在排放口下游 15 公里内被去除。排放口检测到的无机物在法规排放标准范围内。尽管一些无机物质（例如锶、钡和镭）由于共沉淀而在下游浓度降低，但许多无机物质的浓度（包括钠、硫酸盐和硼）由于水蒸发而增加。因此，需要考虑下游水质变化，以充分评估排放 PW 的潜在影响。对于排放口存在的大多数化学物质，人类、牲畜和水生生物的监管健康阈值仍然缺乏。因此，需要进行毒性测试以确定下游用户的潜在健康影响。
