Risk analysis for oil & gas pipelines: A sustainability assessment approach using fuzzy based bow-tie analysis

Vast amounts of oil & gas (O&G) are consumed around the world everyday that are mainly transported and distributed through pipelines. Only in Canada, the total length of O&G pipelines is approximately 100,000 km, which is the third largest in the world. Integrity of these pipelines is of primary interest to O&G companies, consultants, governmental agencies, consumers and other stakeholder due to adverse consequences and heavy financial losses in case of system failure. Fault tree analysis (FTA) and event tree analysis (ETA) are two graphical techniques used to perform risk analysis, where FTA represents causes (likelihood) and ETA represents consequences of a failure event. ‘Bow-tie’ is an approach that integrates a fault tree (on the left side) and an event tree (on the right side) to represent causes, threat (hazards) and consequences in a common platform. Traditional ‘bow-tie’ approach is not able to characterize model uncertainty that arises due to assumption of independence among different risk events. In this paper, in order to deal with vagueness of the data, the fuzzy logic is employed to derive fuzzy probabilities (likelihood) of basic events in fault tree and to estimate fuzzy probabilities (likelihood) of output event consequences. The study also explores how interdependencies among various factors might influence analysis results and introduces fuzzy utility value (FUV) to perform risk assessment for natural gas pipelines using triple bottom line (TBL) sustainability criteria, namely, social, environmental and economical consequences. The present study aims to help owners of transmission and distribution pipeline companies in risk management and decision-making to consider multi-dimensional consequences that may arise from pipeline failures. The research results can help professionals to decide whether and where to take preventive or corrective actions and help informed decision-making in the risk management process. A simple example is used to demonstrate the proposed approach.     

Terrestrial, benthic, and pelagic resource use in lakes: results from a three-isotope Bayesian mixing model

Fluxes of organic matter across habitat boundaries are common in food webs. These fluxes may strongly influence community dynamics, depending on the extent to which they are used by consumers. Yet understanding of basal resource use by consumers is limited, because describing trophic pathways in complex food webs is difficult. We quantified resource use for zooplankton, zoobenthos, and fishes in four low-productivity lakes, using a Bayesian mixing model and measurements of hydrogen, carbon, and nitrogen stable isotope ratios. Multiple sources of uncertainty were explicitly incorporated into the model. As a result, posterior estimates of resource use were often broad distributions; nevertheless, clear patterns were evident. Zooplankton relied on terrestrial and pelagic primary production, while zoobenthos and fishes relied on terrestrial and benthic primary production. Across all consumer groups terrestrial reliance tended to be higher, and benthic reliance lower, in lakes where light penetration was low due to inputs of terrestrial dissolved organic carbon. These results support and refine an emerging consensus that terrestrial and benthic support of lake food webs can be substantial, and they imply that changes in the relative availability of basal resources drive the strength of cross-habitat trophic connections.     

A global community-sourced assessment of the state of conservation technology

Conservation technology holds the potential to vastly increase conservationists’ ability to understand and address critical environmental challenges, but systemic constraints appear to hamper its development and adoption. Understanding of these constraints and opportunities for advancement remains limited. We conducted a global online survey of 248 conservation technology users and developers to identify perceptions of existing tools’ current performance and potential impact, user and developer constraints, and key opportunities for growth. We also conducted focus groups with 45 leading experts to triangulate findings. The technologies with the highest perceived potential were machine learning and computer vision, eDNA and genomics, and networked sensors. A total of 95%, 94%, and 92% respondents, respectively, rated them as very helpful or game changers. The most pressing challenges affecting the field as a whole were competition for limited funding, duplication of efforts, and inadequate capacity building. A total of 76%, 67%, and 55% respondents, respectively, identified these as primary concerns. The key opportunities for growth identified in focus groups were increasing collaboration and information sharing, improving the interoperability of tools, and enhancing capacity for data analyses at scale. Some constraints appeared to disproportionately affect marginalized groups. Respondents in countries with developing economies were more likely to report being constrained by upfront costs, maintenance costs, and development funding (p = 0.048, odds ratio [OR] = 2.78; p = 0.005, OR = 4.23; p = 0.024, OR = 4.26), and female respondents were more likely to report being constrained by development funding and perceived technical skills (p = 0.027, OR = 3.98; p = 0.048, OR = 2.33). To our knowledge, this is the first attempt to formally capture the perspectives and needs of the global conservation technology community, providing foundational data that can serve as a benchmark to measure progress. We see tremendous potential for this community to further the vision they define, in which collaboration trumps competition; solutions are open, accessible, and interoperable; and user-friendly processing tools empower the rapid translation of data into conservation action. Article impact statement: Addressing financing, coordination, and capacity-building constraints is critical to the development and adoption of conservation technology.     

Spatial Variation of Airborne Lead Concentration in an Urban Area

Ambient lead level concentrations have been measured during a three month period at 21 sampling sites in and near Champaign-Urbana, Illinois. Concentrations were determined at downtown, university, residential, suburban, and rural locations. The individual contributions from local sources and background to the Pb concentration in the urban area were determined from measurements and a mathematical model. From a statistical analysis of the data, it is shown that there are no significant differences among the nine residential sites. The group means of residential, university, and downtown stations are significantly different.     

Requiring belt use as part of a school parking permit program: does it increase students' belt use?

OBJECTIVE: Teenagers have very high motor vehicle crash rates, and their use of seat belts is generally lower than that of adults. A potential school-based strategy to increase teenagers' belt use is a policy making parking privileges contingent on belt use by student drivers and their passengers. This study evaluated the effects of implementing a school belt policy. METHODS: The effects of a belt policy were evaluated during the 2003-2004 school year at high schools in two states: Connecticut, a state with a primary enforcement belt law and high belt use rates, and Mississippi, a state with a secondary enforcement law and generally low use rates. Both schools enforced the policy, and violations resulted in a graduated set of penalties leading to the potential loss of parking privileges. Baseline and post-policy belt use rates were obtained from observation surveys of student drivers and their teenage passengers coming to and from school. Changes in belt use were examined relative to belt use trends at comparison schools without a belt policy. Implementation of the policies also was monitored. RESULTS: In Mississippi, among students arriving at school in the morning, driver belt use increased from 42% before the policy to 67% about 6 months after; passenger belt use increased from 16% to 61%, although sample sizes were small. These increases were significantly larger than expected, based on belt use trends at the comparison school in Mississippi. In Connecticut, where 86% of drivers and 79% of their passengers already were belted prior to the policy, there was no significant change. Both schools publicized and monitored the belt policy, and most enforcement occurred in the morning as students arrived at school. CONCLUSIONS: Based on a small-scale application of a belt policy at two schools in different states, a school belt policy may have stronger effects in states where belt use is low. Strong penalties and enforcement are essential elements of an effective policy. Adequate resources and commitment are needed for schools to implement and monitor the type of strong policy needed to sustain high belt use rates. Replication of this study in additional schools appears warranted.     

The fate and persistence of trifluoroacetic and chloroacetic acids in pond waters

The environmental fate of trichloro-, dichloro-, and monochloroacetic acids, and trifluoroacetic acid was investigated using field aquatic microcosms and laboratory sediment-water systems. Trifluoroacetic acid was extremely persistent and showed no degradation during a one-year field study, though it appeared to undergo transient partitioning within an unknown pond phase as the temperature of the surroundings was reduced. Of the three chloroacetic acids, trichloro had the longest residence time (induction and decay) (approximately 40 d), dichloro the shortest (approximately 4 d), and monochloro an intermediate residence time (approximately 14 d). Laboratory studies suggest that the biodegradation of trichloro-, dichloro-, and monochloroacetic acids leads primarily to the formation of chloride and oxalic, glyoxalic, and glycolic acids, respectively.     

Airborne observations of vegetation and implications for biogenic emission characterization

Measuring hydrocarbons from aircraft represents one way to infer biogenic emissions at the surface. The focus of this paper is to show that complementary remote sensing information can be provided by optical measurements of a vegetation index, which is readily measured with high temporal coverage using reflectance data. We examine the similarities between the vegetation index and in situ measurements of the chemicals isoprene, methacrolein, and alpha-pinene to estimate whether the temporal behavior of the in situ measurements of these chemicals could be better understood by the addition of the vegetation index. Data were compared for flights conducted around Houston in August and September 2000. The three independent sets of chemical measurements examined correspond reasonably well with the vegetation index curves for the majority of flight days. While low values of the vegetation index always correspond to low values of the in situ chemical measurements, high values of the index correspond to both high and low values of the chemical measurements. In this sense it represents an upper limit when compared with in situ data (assuming the calibration constant is adequately chosen). This result suggests that while the vegetation index cannot represent a purely predictive quantity for the in situ measurements, it represents a complementary measurement that can be useful in understanding comparisons of various in situ observations, particularly when these observations occur with relatively low temporal frequency. In situ isoprene measurements and the vegetation index were also compared to an isoprene emission inventory to provide additional insight on broad issues relating to the use of vegetation indices in emission database development.     

Groundwater Impacts on Surface Water and Sediment—Gowanus Canal,Brooklyn, New York

The Gowanus Canal Superfund Site in Brooklyn, New York, is an approximately 1.5‐mile (1.61‐km) long estuary that was historically converted into a canal for industrial and commercial purposes. Three manufactured gas plants (MGPs) were formerly located on the Gowanus Canal and discharged waste into it. Surface sediments remain highly contaminated with polycyclic aromatic hydrocarbons (PAHs) long after the MGPs were razed. A hydrogeologic assessment indicates that groundwater passes through the deeper coal tar–contaminated sediment prior to discharging to the canal. This study was undertaken to investigate if groundwater passing through coal tar–contaminated sediment could be responsible for the ongoing contamination of both surface sediments and surface water in the canal. PAH compound distributions in surface water samples collected from the tidal canal at low tide were compared with PAH compounds found in adjacent groundwater‐monitoring wells, point sources (combined sewer overflows [CSOs]), and surface sediments. The results indicate a strong correlation between PAH contaminant distributions in groundwater, sediment, and surface water, indicating that contaminated groundwater passing through the deeper coal tar–contaminated sediments is the primary mechanism contributing to the contamination of both surface sediment and surface water in the canal. Therefore, any sediment remediation efforts in the Gowanus Canal that fail to evaluate and control the upward transport processes have a high chance of failure due to recontamination from below.  ©2016 Wiley Periodicals, Inc.