Broken Pipeline Research Articles

Case study of bearing capacity failure in a 4-story reinforced concrete building

This case history analyzes the bearing capacity failure of a 4-story reinforced concrete building in Benghazi, Libya, constructed in Fall 2000. The building has a plan area of 65 m² and is supported by an 80 cm thick raft foundation resting on collapsible sandy loess, which can lose shear strength when wet. Several months before the building's failure, nearby construction work caused a broken pipeline, leading to significant water leakage. This moisture infiltrated the soil under the foundation, reducing its bearing capacity, particularly on the northern side. In winter 2002, the building began to tilt northward due to this reduced capacity, although inspections revealed no structural cracks, attributed to the rigidity of the raft foundation and reinforced concrete shear walls. The paper discusses the geotechnical properties of the supporting soil and uses finite element analysis to show that the bearing pressures exceeded allowable limits under wet conditions, emphasizing the importance of moisture content in assessing soil stability. This case highlights the complexities of foundation design and the critical impact of environmental factors on soil behavior, advocating for thorough geotechnical assessments and ongoing monitoring of conditions around structural foundations.

The broken pipeline: Challenges in disseminating research on adolescent digital media use.

The broken pipeline: Challenges in disseminating research on adolescent digital media use.

The Potential Impact of Oil Spills in Coastal Waters on Water Supply in Trinidad

Oil exploration poses an inherent risk to water resources and water quality, exemplified by oil spills resulting from broken pipelines, underwater blowouts and oil transport vessel accidents. In these instances, as vulnerable to spilled oil, water is usually the first casualty, resulting in oil contaminated water. In an effort to ensure the sustainability of freshwater resources resilience in Small Island Developing States, (SIDS), desalination is increasingly used to provide potable water. Thus, oceanic oil spills are of significant relevance to the provision of a guaranteed supply of potable water. Trinidad and Tobago, an oil-producing (SIDS), with considerable oil and gas activities on land and in shallow coastal waters; can become increasingly stressed from oil spills, possibly leading to halting seawater intakes in the desalination process. A real-life seawater surface oil spill in the Gulf of Paria, south-west coast of Trinidad, not far from the largest desalination plant in the Caribbean, is investigated using numerical mathematical modelling to model the spill’s movement underwater. The trajectory plots produced and analysed, indicated that depending on key parameters of the oil and the current ambient conditions, an oil plume can travel significantly long horizontal distances underwater before destabilising. Inferences suggested that oily underwater and existing ambient conditions can potentially affect the desalination equipment. Hence, oil spill modelling is necessary to determine oil trajectory and further inform the decision-making process in determining the best location for constructing desalination plants so as to minimise disruption to the island’s domestic freshwater supply in oil spill events.

Postdoctoral National Institutes of Health F32 Grants: Broken Pipeline in the Development of Surgeon-Scientists.

We examined trainees in surgery and internal medicine who received National Institutes of Health (NIH) F32 postdoctoral awards to determine their success rates in obtaining future NIH funding. Trainees participate in dedicated research years during residency (surgery) and fellowship (internal medicine). They can obtain an NIH F32 grant to fund their research time and have structured mentorship. We collected NIH F32 grants (1992-2021) for Surgery Departments and Internal Medicine Departments from NIH RePORTER, an online database of NIH grants. Nonsurgeons and noninternal medicine physicians were excluded. We collected demographic information on each recipient, including gender, current specialty, leadership positions, graduate degrees, and any future NIH grants they received. A Mann-Whitney U test was used for continuous variables, and a χ 2 test was utilized to analyze categorical variables. An alpha value of 0.05 was used to determine significance. We identified 269 surgeons and 735 internal medicine trainees who received F32 grants. A total of 48 surgeons (17.8%) and 339 internal medicine trainees (50.2%) received future NIH funding ( P < 0.0001). Similarly, 24 surgeons (8.9%) and 145 internal medicine trainees (19.7%) received an R01 in the future ( P < 0.0001). Surgeons who received F32 grants were more likely to be department chair or division chiefs ( P =0.0055 and P < 0.0001). Surgery trainees who obtain NIH F32 grants during dedicated research years are less likely to receive any form of NIH funding in the future compared with their internal medicine colleagues who received F32 grants.

Five-Year Monitoring of a Desert Burrow-Dwelling Spider Following an Environmental Disaster Indicates Long-Term Impacts.

Simple SummaryDeserts are characterized by unpredictable precipitation, extreme temperatures, and plants and animals that are specialized to live in these habitats. Consequently, desert organisms often recover slowly, if at all, from human-induced environmental disasters. We studied the effects of two nearby oil spills from a broken pipeline, one that occurred in 1975 and another recent one in 2014, on a burrow-dwelling spider in the extreme desert of the ‘Arava valley (Israel). We compared the abundance of spider burrows in plots contaminated by the oil with nearby unaffected plots over a 4-year period. The abundance was significantly lower in plots with oil-contaminated soil, both in the recent (2014) oil spill area and in the area affected by the 1975 spill. In the laboratory, we found that when offered oil-contaminated versus clean desert soil substrates, spiders chose the clean soil substrate. We conclude that the populations of this burrow-dwelling spider were affected negatively by the oil spills and, furthermore, showed long-lasting impacts from a 40-year-old spill. We propose that burrow-dwelling spiders can be used as effective bioindicators of persistent soil pollution in desert habitats.Deserts are characterized by unpredictable precipitation and extreme temperatures. Their fauna and flora are sensitive to anthropogenic environmental changes, and often recover slowly from environmental disasters. The effects of oil spills on the biota of desert regions, however, have scarcely been studied. We predicted that terrestrial invertebrates suffer long-term negative effects from an oil spill, due to their close association with the substrate. Thus, we investigated the effects of two oil spills that occurred in 1975 and 2014 in the hyper-arid ‘Arava desert (Israel), on a spider that constructs silk-lined nests in burrows in compact, sandy soil in this extreme desert habitat. The spider, Sahastata aravaensis sp. nov. (Filistatidae), is described herein. We assessed spider burrow abundance in plots located in oil-contaminated and nearby uncontaminated clean soil (control) areas over five consecutive years and measured habitat characteristics in these plots. In the laboratory, we determined the preference of individuals for clean vs. oil-contaminated soil as a resting substrate. Finally, as this species was previously undescribed, we added a new species description. The abundance of Sahastata was significantly lower in oil-contaminated plots, and this was the case in the 40-year-old oil spill (1975) as well as in the recent one (2014). In laboratory tests, spiders showed a significant preference for the clean soil substrate over the oil-contaminated substrate. In the field, soil crust hardness and vegetation density did not differ significantly between oil-contaminated and control plots, but these measures were highly variable. The burrows were significantly clustered, suggesting that the young disperse only short distances. In the laboratory adult spiders did not dig burrows, perhaps indicating that adults remain permanently in their natal burrows and that in the field they may use vacant burrows. We conclude that Sahastata populations were affected negatively by the oil spills and these effects were long-lasting. We propose that by monitoring their spatial distribution, burrow-dwelling spiders such as Sahastata can be used as effective bioindicators of soil pollution in desert habitats.

A Broken Pipeline: Effects of Gender and Racial/Ethnic Barriers on College Students’ Educational Aspiration–Pursuit Gap

This study examined the long-term effects of perceived educational and career barriers due to sexism and racism in college students’ pursuit of postgraduate education (PE) and how such effects were different across gender and racial majority/minority groups. With a sample of 2,717 undergraduate students, results from multinomial logistic regression showed that female and students of color not only perceived higher levels of barriers due to sexism and racism, such experiences further predicted the discrepancies between their precollege aspirations and actual pursuit for postgraduate degrees upon graduation. The higher the perceived barriers, the higher the odds of female and students of color not pursuing PE that they had aspired before college. This negative long-term effect was not observed in male students or White students. Moreover, when intersectionality was considered, women of color was the only group where perceived barriers had significant negative effects on the PE gap. Implications were discussed.

Identity &amp; Museum Practice: Promises, Practices, and a Broken Pipeline

AbstractAcknowledging and representing identities in ways that connect with contemporary society is one of the most complicated, contested and perhaps critical challenges facing museums. To explore how museums are addressing that challenge, we turned to a source of research that is rigorous, cross‐ disciplinary and often grounded in contemporary ideas of museums as sites of social activism‐doctoral dissertations and master’s theses. We analyzed almost a hundred studies and conducted interviews with 12 of the authors to explore how their research informed their practice. The studies demonstrate a range of ways that museums can and are engaging with complex ideas about identity, largely through exhibitions; occasionally through collections, collaborations, and programs; and only rarely through institutional operations. The studies position identity as core to museum work and perhaps an overlooked variable in the efforts to promote diversity, inclusion, and equity. Drawing from different disciplines, they describe identity as complex, fluid, dynamic, and intimately related to both personal experiences and societal structures of power. The studies provide compelling arguments for why museums need to change the ways they address, acknowledge, and represent identities. These arguments fell into three categories: Opportunity, Responsibility, and Survival. Interviews identified barriers to entering or advancing within the field for individuals who encompass different life experiences and perspectives. Although a small sample, we believe their experiences demonstrate a broken career pipeline that may contribute to the lack of diversity in the field. We conclude that graduate student research may provide a unique catalyst for social change.

Optimization design of a honeycomb-hole submarine pipeline under a hydrodynamic landslide impact

Submarine pipelines are likely to be impacted by frequently catastrophic landslides, resulting in broken pipelines and causing irreversible economic losses; however, because pipelines located in deep-sea environments are simply laid atop the seabed, effective protective measures have not yet been proposed. In this paper, a pipeline with a uniform distribution of honeycomb holes on the surface, namely, a honeycomb-hole submarine pipeline, is discussed and optimized in detail. A computational fluid dynamics (CFD) approach is verified and improved several times and then applied to conduct 120 numerical simulations for 12 types of suspended submarine pipelines under 10 conditions covering the Reynolds number range required by the project conditions. First, the typical characteristics of the impact forces acting on pipelines in a seawater environment are systematically investigated, and the peak drag force is isolated as the most dangerous load caused by a landslide impact. Second, according to the formation and reduction mechanism of the drag force, it is proposed that a honeycomb-hole submarine pipeline can effectively delay the separation of the boundary layer, reduce the impact velocity, prolong the arrival time, and decrease the differential pressure drag force. Finally, two normalized parameters, the depth ratio and area ratio, are established to develop an optimization design methodology, and the optimal design values of honeycomb-hole pipelines are achieved under the support of limited data. This work presents a protective technology for submarine pipelines and provides new insights into the response of fluid-structure interactions.

Silence is not an option

Day, S., Silence is not an option. Geoscientist 30 (6), 5, 2020 https://doi.org/doi: 10.1144/geosci2020-090, Download the pdf here I’ve been doing a lot of reading over the past few days. As protests against police brutality and racial injustice have swept across the world, so many of us have been wondering what we can do. It’s felt more important than ever to listen, to educate ourselves and try to understand. Reading isn’t nearly enough – it’s barely a beginning – but it’s where I’ve started. I’ve been reading about Marguerite Thomas Williams, the first African American geologist to gain a PhD in the United States. After completing her dissertation, ‘A History of Erosion in the Anacostia Drainage Basin’, in 1942, she was appointed a full professor at Miner Teacher’s College – an institution of learning and training for young African American women. Alongside, she taught night classes at Howard University, an institute whose students regularly protested at local cafeterias that refused to serve them due to their race. I’ve been reading about the appalling racism, prejudice and links to slavery in the biographies of some of geology’s most famous figures – Louis Agassiz, who commissioned humiliating photographs of Black slaves to support his belief in their inferior biology. Henry De la Beche, a slave owner vocally opposed to abolition. And I’ve been reading about how our science has profited from slavery and colonialism, supporting White scientists, collections and institutions whilst Black lives suffered. Many people have asked what we do about this; how we reconcile these aspects of our science’s history, and honestly, I don’t know. I just know we can’t ignore it. I’ve been reading people’s testimony of their own experiences of racism in academia, industry and society. #BlackintheIvory, which documents the experience of being Black in academia. #BlackinNature; accounts of Black people feeling unsafe and unwelcome in outside spaces. #BlackinSTEM; people all over the world sharing their stories and offering support. I’ve been reading statistics which paint a bleak picture of diversity in our science and in academia more widely: 10% of UK geology undergraduates are from a Black, Asian or minority ethnic background. Just 2% of UK geology undergraduates are Black, and 1.2% of UKRI studentships are awarded to Black students. I’ve been reading the numerous messages of support and a commitment to change from universities, institutions and employers and wondering how they will translate into action, hoping that this isn’t both the beginning and the end of the conversation. Others have also been researching and learning: on 10 June, thousands of academics and many organisations stopped work as part of #ShutDownSTEM, a global stand against racism in science designed to give time for reflection and planning. It will be interesting to see what changes emerge in the coming days and months as a result. Reading is a silent process. It’s not enough, unless we use it to make noise. We need to be loud and unafraid in our outrage. We need to be vocal in our rejection of racism, bias and discrimination, and in our affirmation that Black Lives Matter. This magazine should be a part of that. If you have thoughts and ideas you’d like to share, we’re listening – whether you want to contribute an article, tell us what you’d like to see more of, or simply share your frustration and your anger. We stand in solidarity with our Black authors, readers and colleagues. Geoscientist magazine is for everyone, and we know we have a lot of work to do. Further reading and sources: You can read more on Marguerite Thomas Williams at https://trowelblazers.com/marguerite-thomas-williams/ For more on Louis Agassiz’s daguerreotypes, and a subsequent lawsuit over their ownership: https://www.nytimes.com/2019/03/20/us/slave-photographs-harvard.html For more on Henry De la Beche’s links to slavery: https://www.ucl.ac.uk/lbs/person/view/2146633718 Data on Higher Education student enrolment by subject and ethnicity is available at https://www.hesa.ac.uk/data-and-analysis/students/table-8 UKRI studentship statistics taken from Leading Routes’ report, ‘The Broken Pipeline’, available at https://leadingroutes.org/launch-the-broken-pipeline-report

MULTIVARIATE CUSUM CONTROL CHART BASED ON THE RESIDUALS OF MULTIOUTPUT LEAST SQUARES SVR FOR MONITORING WATER QUALITY

Monitoring serially dependent processes using conventional control charts yields a high false alarm rate. Multioutput Least Squares Support Vector Regression (MLS-SVR) has the capability to encompass the cross-relatedness between output variables by learning multivariate output variables simultaneously. This research aims to develop a Multivariate Cumulative Sum (MCUSUM) control chart based on the residual obtained from the MLS-SVR model for monitoring autocorrelated data. The inputs of the MLS-SVR are selected using the significant lag of a partial autocorrelation function. The proposed control chart is applied to monitor water quality data and it can detect the assignable causes in those data caused by a broken pipeline.

Pipeline deformation monitoring using distributed fiber optical sensor

Deformation of long distance pipeline takes place more easily under the various adverse factors such as freezing-thaw and earthquake, and oil and gas often leak from the broken pipeline once the deformation has exceeded a previously established threshold. In order to solve the hot issue on the pipeline deformation monitoring, this research was launched on the basis of the combination of distributed fiber optical sensor and conjugate beam method. One finite element model of a pipeline with the length of 50 m and one PVC (Polyvinyl Chloride) pipeline with the length of 4 m were constructed to validate the deformation method, respectively. The finite element pipeline model was loaded vertical displacement at different positions simultaneously, and the PVC pipeline was gradually applied different level of loads at the midspan. In the two tests, the continuous or distributed strain data and the discrete strain data were used to calculate the deformation of the pipeline based on the conjugate beam method. In order to validate the deformation monitoring method, a comparison between the displacement curve calculated by the distributed strain data and that calculated by the discrete strain data was conducted. The results of the two tests indicate that the deformation of the pipeline can be well monitored and the method can be applied to the field applications.

Offshore Oil Spill Incidents: Creating a Database in Brazil

ABSTRACT Brazil has performed an important role in the oil and gas industry mainly because its offshore E&amp;P activities. The volume of oil produced in offshore fields had increased 88% in the last decade and correspond to more than 90% of national production. The maritime Exploration and Production (E&amp;P) operations in Brazil started in the middle of the 1970's. In 1981 a law was promulgated to establish a compulsory environmental permit to many activities, including oil and gas exploration and production activities. Although this regulation has existed for over 25 years, only in 1999 was it effectively brought into force to the E&amp;P sector, with the creation of the oil and gas specialized office integrated to the Intituto Brasileiro de Meio Ambiente e Recursos Naturais Renováveis – IBAMA (Brazilian Federal Environmental Agency). On January 2000 Brazil faced one its worst oil spills, in Guanabara Bay. A broken pipeline owned and operated by Petrobras spilt 1300 tone of bunker fuel into Guanabara Bay, Rio de Janeiro. At that time, Brazil had no clear environmental scenario regarding the oil industry in Brazil: uncoordinated environmental regulations, debilitated environmental agencies and a relapse industry took part in the scenario. As a result of the repercussion of the disaster, in the same year was enacted the Federal Law 9966/2000, the so called “Oil Law”, on the prevention, control and inspection of pollution caused by the releasing of oil and other harmful substances in waters under national jurisdiction. The provisions of the Law 9966 included, among other things, the requirement for the notification to the competent environmental authority, the maritime authority and the oil regulating agency, of any incident which might cause water pollution. Although IBAMA receives the oil spill communications since 2001, only in 2010 the Agency began to include this information in a database. This paper discusses the offshore oil spill data received between 2010 and 2012.

Does phosphate enhance the natural attenuation of crude oil in groundwater under defined redox conditions?

After a crude oil spill caused by a broken pipeline in 2009 to a gravel aquifer in southern France, degradation processes under various redox conditions progressively established, but at rates that predict a long life-time of the source under natural attenuation after partial source removal. In this study, we aimed at identifying the rate-limiting factors for each redox condition, with special emphasis on phosphate as limiting nutrient. The study was conducted in laboratory microcosms assembled with material collected on site: sediments, water from monitoring wells, oil and microbial sludge. Redox conditions were promoted by adding electron acceptors (either oxygen, nitrate, limonite (FeO(OH)), cryptomelane (K(Mn4+,Mn2+)8O16), or sulfate). For each condition, the role of phosphate was studied by repeated additions for up to 290days. The results showed a very strong stimulation of aerobic and denitrifying rates of oil degradation by phosphate, provided that oxygen and nitrate were repeatedly supplied. Phosphate caused also a marked stimulation of methanogenic degradation, and a relatively small stimulation of metal reduction. These anaerobic processes started only after marked lag phases, and phosphate shortened the lag phase for methanogenic degradation. Degradation of aromatic and aliphatic hydrocarbons with less than 8 carbons, including benzene, was confirmed even under unstimulated conditions.It is concluded that degradation rates at the site are limited by both, availability of electron acceptors and availability of phosphate needed for promoting microbial growth.

Long-term effects of oil pollution in mangrove forests (Baixada Santista, Southeast Brazil) detected using a GIS-based multitemporal analysis of aerial photographs

Oil spills are potential threats to the integrity of highly productive coastal wetlands, such as mangrove forests. In October 1983, a mangrove area of nearly 300 ha located on the southeastern coast of Brazil was impacted by a 3.5 million liter crude oil spill released by a broken pipeline. In order to assess the long-term effects of oil pollution on mangrove vegetation, we carried out a GIS-based multitemporal analysis of aerial photographs of the years 1962, 1994, 2000 and 2003. Photointerpretation, visual classification, class quantification, ground-truth and vegetation structure data were combined to evaluate the oil impact. Before the spill, the mangroves exhibited a homogeneous canopy and well-developed stands. More than ten years after the spill, the mangrove vegetation exhibited three distinct zones reflecting the long-term effects of the oil pollution. The most impacted zone (10.5 ha) presented dead trees, exposed substrate and recovering stands with reduced structural development. We suggest that the distinct impact and recovery zones reflect the spatial variability of oil removal rates in the mangrove forest. This study identifies the multitemporal analysis of aerial photographs as a useful tool for assessing a system's capacity for recovery and monitoring the long-term residual effects of pollutants on vegetation dynamics, thus giving support to mangrove forest management and conservation.

Leading Academic Research Institutions Seek Increased NIH Funding

Five consecutive years of flat funding the budget of the National Institutes of Health (NIH) is deterring promising young researchers and threatening the future of Americans' health, a group of seven preeminent academic research institutions warn. In a March 11 report entitled “A Broken Pipeline? Flat Funding of the NIH Puts a Generation of Science at Risk,” a group of 6 research universities and a major teaching hospital describe the toll that cumulative stagnant NIH funding is taking on the American medical research enterprise. The institutions warn that if NIH does not get consistent and robust support in the future, the nation will lose a generation of young investigators to other careers and other countries and, with them, “a generation of promising research that could cure disease for millions for whom no cure currently exists.” The report was co-authored by Brown University, Duke University, Harvard University, The Ohio State University, Partners Healthcare, the University of California Los Angeles, and Vanderbilt University. The “Broken Pipeline” focuses on the effect that recurring flat funding is having on young researchers in particular. However, it notes that competition for limited resources is affecting scientists at every point of the academic research pipeline. According to the 20-page report, fewer resources means that NIH is experiencing a backlog in high-quality research proposals, and too few are getting funded. The overall success rate for NIH research project grants dropped from 32% in 1999 to 24% in 2007. Only about 1 in 4 original research applications to the NIH is being funded, and many of those are only partially funded, and only after lengthy delays and cumbersome reapplications, the report says, noting that “today's researchers are waiting an average of four years longer than they did in 1990 for their first big grant.” Although the success rate has dropped for all R01 applicants, it is particularly low—only 18%—for first-time applicants. First-time R01 recipients also are older. The average age is now 43, up from 39 years in 1990. (R01s are the premier NIH research grants needed to establish a researcher's credibility and independence.) “Without effective national policies to recruit young scientists to the field, and support their research over the long term, in 10 to 15 years, we'll have more scientists older than 65 than those younger than 35. This is not a sustainable trend in biomedical research and must be addressed aggressively,” says Dr Elias A. Zerhouni, Director of the NIH. For more details, see “A Broken Pipeline? Flat Funding of the NIH Puts a Generation of Science at Risk,” available from: www.brokenpipeline.org.

YOUNG SCIENTISTS GET BACKING

LAST WEEK, a coalition of research institutions and Howard Hughes Medical Institute independently announced strategies to support young scientists—including chemists—who are struggling to obtain funding for their biomedical research. Both HHMI and the coalition attribute the researchers’ money problems to funding constraints at the National Institutes of Health. At a March 11 press conference in Washington, D.C., and a subsequent visit to Capitol Hill, representatives of research institutions including Harvard University and the University of California, Los Angeles, called for greater NIH funding. They also released a report entitled “A Broken Pipeline? Flat Funding of the NIH Puts a Generation of Science at Risk.” NIH’s budget doubled between fiscal years 1998 and 2003, the coalition report acknowledges, and rose a further 9% through 2008. In constant dollars, however, the purchasing power of NIH’s budget fell 10% between 2003 and 2008. The report contends that this trend threatens medical progress and ...

Water balance calculation method for urban areas examples from Hungary

A new water balance calculation has been worked out that considers the effect of urbanization. This calculation method was applied to evaluate the water balance of the historic center of Budapest, the Buda Castle Hill, where an intensive network of cellars is found. The method, a combination of hydrogeologic tests and field measurements, was also tested in other Hungarian cities where underground structures are common, such as Eger, Pécs and Veszprém. The calculation considers both natural and anthropogenic water sources. Beside the commonly-used natural factors such as precipitation, evaporation, runoff, infiltration, etc. it also employs input parameters such as broken pipelines and sewer systems. The water losses of these waterworks significantly influence the natural water balance and provide additional and very often significant water input into the water system. The new method is of great importance in designing and planning remedial actions for historic cities, where the built environment, cellars and natural caves are endangered by infiltrating water. Another feedback of the method is the application of the results in the long-term planning strategy of public works supplying or using water (water works, sewer system and energy sector).

Natural attenuation of chlorinated solvents: a comparative study

Sites contaminated by chlorinated solvents have been investigated. Sites Dolni Tresnovec and Zetor located in Czech Republic exhibit relatively reducing conditions. Primary chlorinated solvents are attenuated by reductive dechlorination processes, and plumes have probably reached steady-state at Zetor site. Terminal electron accepting processes (TEAP) are ferric iron reduction and sulfate reduction at respective Dolni Tresnovec and Zetor sites. Source of organic matter at Dolni Tresnovec site is the waste deposited at local landfill. At Zetor site reducing conditions are linked to the petroleum hydrocarbons spill from broken pipeline. In contrast, site Dubnica in Slovak Republic exhibits oxidizing conditions, and natural attenuation of chlorinated solvents occurs mostly by dispersion. Modeling by the program BIOCHLOR indicated formation of steady-state plumes close to source at Zetor site, much longer steady-state plumes at Dolni Tresnovec site, and extremely long plumes at Dubnica site. Results demonstrate an important role of redox conditions in natural attenuation of chlorinated solvents.

Progression of methanogenic degradation of crude oil in the subsurface

Our results show that subsurface crude-oil degradation rates at a long-term research site were strongly influenced by small-scale variations in hydrologic conditions. The site is a shallow glacial outwash aquifer located near Bemidji in northern Minnesota that became contaminated when oil spilled from a broken pipeline in August 1979. In the study area, separate-phase oil forms a subsurface oil body extending from land surface to about 1 m (3.3 ft) below the 6–8-m (20–26 ft)-deep water table. Oil saturation in the sediments ranges from 10–20% in the vadose zone to 30–70% near the water table. At depths below 2 m (6.6 ft), degradation of the separate-phase crude oil occurs under methanogenic conditions. The sequence of methanogenic alkane degradation depletes the longer chain n-alkanes before the shorter chain n-alkanes, which is opposite to the better known aerobic sequence. The rates of degradation vary significantly with location in the subsurface. Oil-coated soils within 1.5 m (5 ft) of land surface have experienced little degradation where soil water saturation is less than 20%. Oil located 2–8 m (6.6–26 ft) below land surface in areas of higher recharge has been substantially degraded. The best explanation for the association between recharge and enhanced degradation seems to be increased downward transport of microbial growth nutrients to the oil body. This is supported by observations of greater microbial numbers at higher elevations in the oil body and significant decreases with depth in nutrient concentrations, especially phosphorus. Our results suggest that environmental effects may cause widely diverging degradation rates in the same spill, calling into question dating methods based on degradation state.

Numerical solution of the problem of gas efflux from a closed volume into atmosphere

The problem of modeling failures in systems of gas transportation, which are accompanied by the efflux of large volumes of natural gas from a broken pipeline into the atmosphere, has been considered. Using numerical methods, the maximum size of a dangerous zone is determined in order to evaluate the scale of catastrophes involving vertical gas outburst (perpendicular to the wind direction).