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A controlled petroleum release was conducted to evaluate bioremediation in a wetland near Houston, Texas. The 140-day study was conducted using a randomized, complete block design to test three treatments with six replicates per treatment. The three treatment strategies were inorganic nutrients, inorganic nutrients with an alternative electron acceptor, and a no-action oiled control. Samples were analyzed for petroleum chemistry and inorganic nutrients. These results are discussed in the context of our related research involving toxicology and microbiology at the site during the experiment. To evaluate biodegradation, the targeted compounds were normalized to the conservative compound C3017alpha, 21beta-[H]hopane, thus reducing the effects of spatial heterogeneity and physical transport. The two biostimulation treatments demonstrated statistically-higher rates of biodegradation than the oiled no-action control. For the majority of the experiment, target nutrient levels were maintained. Further research may be warranted to optimize these bioremediation strategies as well as evaluating additional treatment strategies for wetlands and other shoreline systems. 相似文献
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Recirculating well pairs are a proven means of implementing bioremediation and may also be useful for applying other in situ ground water remediation technologies. A bromide tracer test was performed to characterize the hydraulic performance of a recirculating well pair installed at Moffett Field, California. In particular, we estimate two important properties of the recirculating well pair: (1) the fraction of captured water that is recycled between the wells, and (2) the travel-time distribution of ground water in the induced zone of recirculation. We also develop theoretical estimates of these two properties and demonstrate they depend upon a dimensionless pumping rate, denoted xi. The bromide breakthrough curve predicted from theory agrees well with that determined experimentally at Moffett Field. The minimum travel time between the wells is denoted t(min). In theory, t(min) depends inversely on Q, the pumping rate in the recirculating wells, and is proportional to a2, the square of the distance between the wells. Both the experimental and theoretical travel-time distributions indicate that at least half the recirculating water travels between the wells along fast flowpaths (travel time < 2*t(min)). Therefore, when designing recirculating well pairs, engineers should ensure that t(min) will be sufficiently high to allow biologically mediated reactions (or other in situ remediation processes) sufficient time to proceed. 相似文献
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Introduction With rapid development of national economy, urbanization has been speeded up in China, and several city groups or city belts with extra-large cities as their centers have been formed. For example, Pearl River Delta urbanized area surrounds Guangzhou City, Shenzhen City, Zhuhai City; Yangtze River Delta urbanized area surrounds Shanghai City, Suzhou City, Wuxi City, Nanjing City, Hangzhou City; Beijing-Tianjin-Tangshan urbanized area surrounds Beijing City, Tianjin City… 相似文献
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地震统计区地震活动性参数b值及v4不确定性研究 总被引:5,自引:1,他引:5
本文结合华北地区几个地震统计区的实例,探讨了地震统计区的重要地震活动性参数b值和v4不确定性的主要影响因素及其特征,并研究分析了其不确定性的大小。结果表明,地震活动性参数的不确定性主要影响因素为样本统计时段、样本处理方法、统计下限震级、高震级年平均发生率等。在郯庐地震统计区,b值变化可达0.2以上,v4的变化可达1.4以上,汾渭地震统计区的不确定性也基本相当,河北平原地震统计区因为地震样本相对丰富,不确定性要小许多。 相似文献
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总结和分析了中国地震带划分的研究历史、目的和用途、划分原则、表现形式以及基本特点,指出地震带是以地震活动性区域划分研究为目的,它不同于概率地震危险性方法中的地震统计区的概念.文中对地震统计区概念及其演化历史进行了分析和论述,认为地震统计区与地震带在统计意义、物理内涵、层次性、划分规模的要求、对空间重叠的排斥性以及划分目的和用途等方面,均存在较大差异.现行工作中将两者不加区分地使用是不合适的, 一方面造成地震统计区未形成自身的适应概率地震危险性分析方法的划分理论,另一方面也造成以地震活动特征和地震孕育发生环境、机制研究为目的的地震带划分研究的停滞不前.文中最后指出,地震统计区划分是以地震带划分研究为基础,它产生并服务于考虑地震活动时空不均匀性的概率地震危险性分析方法,应将其与地震带概念加以明确区分,并加强其划分原则、理论和方法的研究. 相似文献
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