Application of Four Measurement Techniques to Understand Natural Source Zone Depletion Processes at an LNAPL Site     

Poonam R. Kulkarni  Charles J. Newell  David C. King  Lisa J. Molofsky  Sanjay Garg 《Ground Water Monitoring & Remediation》2020,40(3):75-88

There are several key data gaps in our understanding of Natural Source Zone Depletion (NSZD) processes at sites impacted by light nonaqueous phase liquid (LNAPL), and quantifying NSZD rates can be challenging due to the inherent differences in measurement methods. In this study, four different NSZD measurement methods (oxygen influx measured by the Gradient Method, long-term carbon dioxide efflux measured with Carbon Traps, instantaneous carbon dioxide efflux measured with Dynamic Closed Chambers (DCC LI-COR), and the long-term heat flux from biodegradation measured by Thermal NSZD monitoring), as well as LNAPL composition and dissolved gas sampling, were applied at a site in Southern California. These techniques were used to evaluate key questions such as: (1) how do different NSZD rate measurement methods compare, and what causes variability in NSZD results?; (2) to what extent NSZD processes are occurring in LNAPL within the saturated zone?; and (3) how is NSZD related to LNAPL composition change over time? Carbon Traps and Thermal NSZD monitoring measurement methods provided the most consistent NSZD data at this geologically heterogeneous site, with two location average NSZD rates of 540 and 480 gal/acre/year, respectively. Overall, comparisons of NSZD rates between methods were challenging due to different measurement timeframes, significant temporal and spatial heterogeneity, and operational challenges with two of the NSZD methods. Finally, samples of subsurface LNAPL were collected for analysis in 2007 and 2016; results indicated that diesel-range constituents were already very degraded and anaerobic degradation of gasoline-range constituents was ongoing. A LNAPL depletion model (Douglas et al. 1996) applied to the measured LNAPL composition change appeared to greatly overestimate the amount of LNAPL depletion compared to the measured NSZD rate, but did provide an independent semiqualitative line of evidence that LNAPL was being depleted by active NSZD processes at the site.  相似文献   

Overview of Natural Source Zone Depletion: Processes,Controlling Factors,and Composition Change          下载免费PDF全文

Sanjay Garg  Charles J. Newell  Poonam R. Kulkarni  David C. King  David T. Adamson  Maria Irianni Renno  Tom Sale 《Ground Water Monitoring & Remediation》2017,37(3):62-81

Natural source zone depletion (NSZD) has emerged as a practical alternative for restoration of light non‐aqueous phase liquid (LNAPL) sites that are in the later stages of their remediation lifecycle. Due to significant research, the NSZD conceptual model has evolved dramatically in recent years, and methanogenesis is now accepted as a dominant attenuation process (e.g., Lundegard and Johnson 2006 ; Ng et al. 2015 ). Most of the methane is generated within the pore space adjacent to LNAPL (Ng et al. 2015 ) from where it migrates through the unsaturated zone (e.g., Amos and Mayer 2006 ), where it is oxidized. While great progress has been made, there are still some important gaps in our understanding of NSZD. NSZD measurements provide little insight on which constituents are actually degrading; it is unclear which rate‐limiting factors that can be manipulated to increase NSZD rates; and how longevity of the bulk LNAPL and its key constituents can be predicted. Various threads of literature were pursued to shed light on some of the questions listed above. Several processes that may influence NSZD or its measurement were identified: temperature, inhibition from acetate buildup, protozoa predation, presence of electron acceptors, inhibition from volatile hydrocarbons, alkalinity/pH, and the availability of nutrients can all affect methanogenesis rates, while factors such as moisture content and soil type can influence its measurement. The methanogenic process appears to have a sequenced utilization of the constituents or chemical classes present in the LNAPL due to varying thermodynamic feasibility, biodegradability, and effects of inhibition, but the bulk NSZD rate appears to remain quasi‐zero order. A simplified version of the reactive transport model presented by Ng et al. 2015 has the potential to be a useful tool for predicting the longevity of key LNAPL constituents or chemical fractions, and of bulk LNAPL, but more work is needed to obtain key input parameters such as chemical classes and their biodegradation rates and any potential inhibitions.  相似文献   

Impact of Temperature on Groundwater Source Attenuation Rates at Hydrocarbon Sites          下载免费PDF全文

Poonam R. Kulkarni  David C. King  Thomas E. McHugh  David T. Adamson  Charles J. Newell 《Ground Water Monitoring & Remediation》2017,37(3):82-93

The temperature sensitivity of microbial populations is reflected in measured source attenuation rates at hydrocarbon‐impacted sites. The objective of this study was to evaluate the correlation between temperature and source attenuation rates (concentration vs. time attenuation rate over many years) of benzene and toluene by analyzing groundwater monitoring data from >2000 hydrocarbon sites. Historical monitoring records were obtained from three databases, processed to yield long‐term multiyear source attenuation rates, and then compared with representative temperatures at each site. Statistically significant and positive relationships between temperature and source attenuation rates were established for benzene and toluene, indicating that temperature does impact hydrocarbon degradation, but is one of many factors that contribute to source attenuation. There was an observed 1.1 to 1.6 times increase in attenuation rates per 10 °C increase in temperature, which is less than the rate increases predicted by the Arrhenius equation. The temperature dependence on attenuation rate is consistent with several lines of evidence that methanogenesis plays a key role in the rate of hydrocarbon source zone attenuation rather than being controlled strictly by the availability of electron acceptors. First, methanogenesis is known to be strongly influenced by temperature, with significantly higher rates up to about 35 °C. Second, the temperature‐degradation rate relationship was stronger at sites with deeper water tables (>30 ft) that are less susceptible to oxygen influx than sites with shallow water tables (<15 ft). Third, dissolved methane concentrations were higher at sites with warmer temperatures. Overall, these results provide indirect support for a conceptual model where methanogenesis is a key degradation process at hydrocarbon sites, and that attenuation of these source zones is temperature‐sensitive.  相似文献   

Performance of DNAPL Source Depletion Technologies at 59 Chlorinated Solvent-Impacted Sites   总被引：6，自引：1，他引：5  

Travis M. McGuire  James M. McDade  Charles J. Newell 《Ground Water Monitoring & Remediation》2006,26(1):73-84

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Harold Urey and the moon     

Homer E. Newell 《Earth, Moon, and Planets》1973,7(1-2):1-5

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Ecology of coastal waters: A systems approach: K. H. MannBlackwell Scientific Publications,Oxford, 1982, ix + 322 pp, £25·00 (cloth) £10·80 (paper)     

R.C. Newell 《Estuarine, Coastal and Shelf Science》1983,17(5):589-590

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Results of the first North American comparison of absolute gravimeters, NACAG-2010     

D. Schmerge  O. Francis  J. Henton  D. Ingles  D. Jones  J. Kennedy  K. Krauterbluth  J. Liard  D. Newell  R. Sands  A. Schiel  J. Silliker  D. van Westrum 《Journal of Geodesy》2012,86(8):591-596

The first North American Comparison of absolute gravimeters (NACAG-2010) was hosted by the National Oceanic and Atmospheric Administration at its newly renovated Table Mountain Geophysical Observatory (TMGO) north of Boulder, Colorado, in October 2010. NACAG-2010 and the renovation of TMGO are part of NGS’s GRAV-D project (Gravity for the Redefinition of the American Vertical Datum). Nine absolute gravimeters from three countries participated in the comparison. Before the comparison, the gravimeter operators agreed to a protocol describing the strategy to measure, calculate, and present the results. Nine sites were used to measure the free-fall acceleration of g. Each gravimeter measured the value of g at a subset of three of the sites, for a total set of 27 g-values for the comparison. The absolute gravimeters agree with one another with a standard deviation of 1.6?μGal (1 Gal ≡ 1?cm s ^?2). The minimum and maximum offsets are ?2.8 and 2.7?μGal. This is an excellent agreement and can be attributed to multiple factors, including gravimeters that were in good working order, good operators, a quiet observatory, and a short duration time for the experiment. These results can be used to standardize gravity surveys internationally.  相似文献   

A conceptual template for integrative human–environment research     

Barry Newell  Carole L. Crumley  Nordin Hassan  Eric F. Lambin  Claudia Pahl-Wostl  Arild Underdal  Robert Wasson   《Global Environmental Change》2005,15(4):299-307

Knowledge integration, the blending of concepts from two or more disciplines to create innovative new worldviews, is a key process in attempts to increase the sustainability of human activities on Earth. In this paper, we describe a ‘conceptual template’ that can be used to catalyse this process. The template comprises (a) a list of high-level concepts that capture the essential aspects of any significant human–environment problem, plus (b) broad lists of low-level basic concepts drawn from a range of disciplines. Our high-level concepts, which we call ‘conceptual clusters’, are labelled Dynamics & System, Organisation & Scale, Controlling Models, Management & Policy, Adaptation & Learning, and History. Many of the clustered, lower-level concepts are synonyms and thus provide possible connections between disciplines—for this reason we call them ‘nexus concepts’. We suggest that a conceptual template like that presented here can provide strong support to the initial phases of integrative research programs.  相似文献   

H<Subscript>2</Subscript>-rich and Hydrocarbon Gas Recovered in a Deep Precambrian Well in Northeastern Kansas     

K. David Newell  John H. Doveton  Daniel F. Merriam  Barbara Sherwood Lollar  William M. Waggoner  L. Michael Magnuson 《Natural Resources Research》2007,16(3):277-292

In late 2005 and early 2006, the WTW Operating, LLC (W.T.W. Oil Co., Inc.) #1 Wilson well (T.D. = 5772 ft; 1759.3 m) was drilled for 1826 ft (556.6 m) into Precambrian basement underlying the Forest City Basin in northeastern Kansas. Approximately 4500 of the 380,000 wells drilled in Kansas penetrate Precambrian basement. Except for two previous wells drilled into the arkoses and basalts of the 1.1-Ga Midcontinent Rift and another well drilled in 1929 in basement on the Nemaha Uplift east of the Midcontinent Rift, this well represents the deepest penetration into basement rocks in the state to date. Granite is the typical lithology observed in wells that penetrate the Precambrian in the northern Midcontinent. Although no cores were taken to definitively identify lithologies, well cuttings and petrophysical logs indicate that this well encountered basement metamorphic rocks consisting of schist, gneiss, and amphibolitic gneiss, all cut by aplite dikes. The well was cased and perforated in the Precambrian, and then acidized. After several days of swabbing operations, the well produced shows of low-Btu gas, dominated by the non-flammable component gases of nitrogen (20%), carbon dioxide (43%), and helium (1%). Combustible components include methane (26%), hydrogen (10%), and higher molecular-weight hydrocarbons (1%). Although Coveney and others [Am. Assoc. Petroleum Geologists Bull., v. 71, no, 1, p. 39–48, 1987] identified H₂-rich gas in two wells located close to the Midcontinent Rift in eastern Kansas, this study indicates that high levels of H₂ may be a more widespread phenomenon than previously thought. Unlike previous results, the gases in this study have a significant component of hydrocarbon gas, as well as H₂, N₂, and CO₂. Although redox reactions between iron-bearing minerals and groundwater are a possible source of H₂ in the Precambrian basement rocks, the hydrocarbon gas does not exhibit the characteristics typically associated with proposed abiogenic hydrocarbon gases from Precambrian Shield sites in Canada, Finland, and South Africa. Compositional and isotopic signatures for gas from the #1 Wilson well are consistent with a predominantly thermogenic origin, with possible mixing with a component of microbial gas. Given the geologic history of uplift and rifting this region, and the major fracture systems present in the basement, this hydrocarbon gas likely migrated from source rocks and reservoirs in the overlying Paleozoic sediments and is not evidence for abiogenic hydrocarbons generated in situ in the Precambrian basement.  相似文献   

安徽女山麻粒岩包体：矿物学特征、下地壳地温曲线及其成因意义   总被引：10，自引：2，他引：10  

黄小龙  徐义刚  王汝成  陈小明 《岩石学报》2002,18(3):383-391

女山玄武岩中麻粒岩包体的主要矿物组合为 Opx+Cpx+Pl,均呈条带状构造 ,具有细粒粒状变晶结构或不等粒结构。女山麻粒岩包体的斜方辉石及单斜辉石的化学成分都非常相似于华北太古代麻粒岩地体 ,而明显区别于汉诺坝麻粒岩包体。通过对世界上含石榴石麻粒岩的检验 ,表明 Wells(1977) :二辉石温度计与 Mc Carthy & Pati～no Douce(1998)的 Cpx+Pl+Qz压力计的温压计组合是计算麻粒岩平衡温压的可行方法 ,并得到了女山麻粒岩包体平衡温度分布于 80 9～ 899℃之间 ,主要集中于 85 0± 2 0 C,平衡压力为 0 .6 0～ 0 .95 GPa。由麻粒岩包体的平衡温压所建立起的女山地区下地壳地温曲线与 Xuet a1.(1998)建立的上地幔地温曲线上延部分非常吻合。根据地温线推得的“岩石学”Moho面深度为 31km土 ,与“地震”Moho面深度相一致 ,表明女山地区不具有明显的壳幔过渡带。女山地区缺乏强烈的底侵作用以及麻粒岩包体的特征矿物化学成分暗示了女山麻粒岩包体可能来源于华北克拉通结晶基底  相似文献