Temporal Trends of Young-of-Year Fishes in Lake Erie and Comparison of Diel Sampling Periods

We explored temporal trends of young-of-year (YOY) fishes caught in bottom trawl hauls at an established offshore monitoring site in Lake Erie in fall during 1961–2001. Sampling was conducted during morning, afternoon, and night in each year. Catches per hour (CPH) of alewife (Alosa pseudoharengus) YOY were relatively low and exhibited no temporal trend. This result was consistent with the species’ intolerance to Lake Erie’s adverse winter water temperatures. Gizzard shad (Dorosoma cepedianum) YOY decreased sharply after 1991, which was consistent with recent oligotrophication of the lake. Following the establishment in 1979 and rapid increase of white perch (Morone americana) YOY, white bass (Morone chrysops) and freshwater drum (Aplodinotus grunniens) YOY decreased. Trout-perch (Percopsis omiscomaycus) YOY decreased during 1986–1991, but recovered to previous levels during 1991–2001. The recovery coincided with the resurgence of mayflies (Ephemoptera) in the lake. CPH of spottail shiner (Notropis hudsonius) and emerald shiner (N. atherinoides) YOY exhibited no temporal trend between 1961 and the late 1970s to early 1980s. CPH of yellow perch (Perca flavescens) YOY decreased during 1961–1988, and walleye (Sander vitreum) YOY increased overall during the time series. These observations were consistent with published studies of adults in the region. CPH of 4 of the 10 species of YOY considered were greatest during night. CPH for walleye YOY was higher in the morning than in the afternoon, but there was no significant difference between night and morning abundances. The results suggest that (1) CPH of YOY fishes may be a useful monitoring tool for Lake Erie, and (2) offshore monitoring programs that do not include night sampling periods may underestimate recruitment for several common species.     

A rough set-based quality function deployment (QFD) approach for environmental performance evaluation: a case of offshore oil and gas operations

Activities in offshore oil and gas (OOG) that cause environmental impacts can be systematically managed through an environmental management system (EMS). Environmental performance evaluation (EPE) is an essential part of an EMS. However, previous studies on EPE indicate that existing lists of indicators little insight into how indicators are modified to more accurately assess environmental performance.In this paper, a way is proposed to identify and define specific environmental performance indicators on a case-by-case basis, which consists of five steps: (1) describing environmental requirements; (2) determining favourable outcomes corresponding to the requirements; (3) identifying required activities or issues to achieve the outcomes; (4) searching for proper measures of the activities or issues; and (5) generating a list of key indicators. Based on these steps, a quality function deployment (QFD) approach is developed to determine key indicators and evaluate environmental performance. To handle uncertainties in QFD, the decision makers’ evaluations are quantified through rough numbers using the concept of rough sets. The outputs of the proposed approach are different environmental performance indices. Using these indices, decision makers can easily determine whether an improved performance has been achieved through an EMS. The proposed approach is transparent and promising for use as a unified tool for EPE. An application of the proposed approach is demonstrated through a numerical example.     

浙江北部海域春季浮游动物的群落结构研究

根据2007年春季在浙江北部海域所采集的浮游动物样品,对该调查海域浮游动物的种类组成、丰度、生物量和生物多样性进行了探讨,采用多元统计软件PRIMER 5分析了该海域浮游动物的群落结构。研究结果表明,调查海域共鉴定各类浮游动物62种、浮游幼虫12种,合计74种。经统计共有2种优势种,分别是中华哲水蚤(Calanus sinicus)和五角水母(Muggiaea atlantica)。浮游动物生物量和丰度的平面分布比较相似,主要分布在调查海域的东部和东南部,并存在着向东南方向呈递增的趋势,而在杭州湾内的值比较小。调查海域浮游动物生物多样性比较低,平均值为1.54。根据对本次调查获得的浮游动物群落结构的聚类分析,主要存在着两个生态类群,群落Ⅰ为沿岸低盐群落,群落Ⅱ为暖温带近海群落。     

Rapid removal of polyacrylamide from wastewater by plasma in the gas–liquid interface

Due to the severe restrictions imposed by legislative frameworks, the removal of polyacrylamide(PAM) rapidly and effectively from produced wastewater in offshore oilfields before discharge is becoming an urgent challenge. In this study, a novel advanced oxidation process based on plasma operated in the gas–liquid interface was used to rapidly decompose PAM, and multiple methods including viscometry, flow field-flow fractionation multi-angle light scattering, UV–visible spectroscopy, and attenuated total reflectanceFourier transform infrared spectroscopy were used to characterize the changes of PAM.Under a discharge voltage of 25 kV and pH 7.0, the PAM concentration decreased from 100 to 0 mg/L within 20 min and the total organic carbon(TOC) decreased from 49.57 to1.23 mg/L within 240 min, following zero-order reaction kinetics. Even in the presence of background TOC as high as 152.2 mg/L, complete removal of PAM(100 mg/L) was also achieved within 30 min. The biodegradability of PAM improved following plasma treatment for 120 min. Active species(such as O_3 and H_2O_2) were produced in the plasma. Hydroxyl radical was demonstrated to play an important role in the degradation of PAM due to the inhibitory effect observed after the addition of an ·OH scavenger, Na_2CO_3. Meanwhile, the release of ammonia and nitrate nitrogen confirmed the cleavage of the acylamino group.The results of this study demonstrated that plasma, with its high efficiency and chemicalfree features, is a promising technology for the rapid removal of PAM.     

The oil and gas industry,the Offshore Installation Manager (OIM) and the management of emergencies - Changes necessary to achieve effective competence assessment of OIMs in controlling emergencies

Within the UK offshore oil and gas industry all installations require to be under the charge of a ‘competent’ installation manager in accordance with the Offshore Installations and Pipeline Works (Management and Administration) Regulations (MAR) 1995. The Offshore Installation Manager (OIM) is responsible for the safety of all persons onboard and within 500 m of an installation. Should an incident arise, the OIM performs one of the most critical roles within the offshore industry - management of the response to the emergency to mitigate and make safe the installation to secure a place of safety for persons onboard or organise their safe evacuation. The emergency response also includes limiting the loss of hydrocarbons to the environment.Research at the University of Aberdeen has identified 8 potential barriers to the effective competence assessment of OIMs in controlling emergencies. These underlying barriers are a consequence of current UK legislation and industry practices in the assessment of OIM competence and result from:

• •multiple definitions of competence,
• •competence assessment predominantly by observation,
• •lack of specific and unambiguous competence requirements for trainers and assessors,
• •complexity in UK legislation and complicated interpretation of terms,
• •lack of statutory competence requirements for OIMs in controlling emergencies,
• •lack of ownership of OIM competence and competence assessment,
• •complex interactions across multiple UK Government departments, and
• •lack of regulation and independent audit of the competence assessment process of OIMs in controlling emergencies.

The potential barriers were identified by qualitative analysis of key documentation, including legislation, using a critical hermeneutic approach. Hermeneutics has historically been used to analyse texts within the domains of theology, business and law. It arguably, however, represents a powerful approach to the study of documents within the engineering domain and the offshore oil and gas industry.This paper discusses the identified potential barriers, research conclusions and recommendations and represents the culmination of three years of doctoral research investigating the competence assessment of OIMs in controlling emergencies within the offshore oil and gas industry. The research, in particular, is relevant to Duty Holders within the offshore industry, safety engineers and UK Government departments.     

Offshore safety case approach and formal safety assessment of ships

PROBLEM: Tragic marine and offshore accidents have caused serious consequences including loss of lives, loss of property, and damage of the environment. METHOD: A proactive, risk-based "goal setting" regime is introduced to the marine and offshore industries to increase the level of safety. DISCUSSION: To maximize marine and offshore safety, risks need to be modeled and safety-based decisions need to be made in a logical and confident way. Risk modeling and decision-making tools need to be developed and applied in a practical environment. SUMMARY: This paper describes both the offshore safety case approach and formal safety assessment of ships in detail with particular reference to the design aspects. The current practices and the latest development in safety assessment in both the marine and offshore industries are described. The relationship between the offshore safety case approach and formal ship safety assessment is described and discussed. Three examples are used to demonstrate both the offshore safety case approach and formal ship safety assessment. The study of risk criteria in marine and offshore safety assessment is carried out. The recommendations on further work required are given. IMPACT ON INDUSTRY: This paper gives safety engineers in the marine and offshore industries an overview of the offshore safety case approach and formal ship safety assessment. The significance of moving toward a risk-based "goal setting" regime is given.     

Geosynthetics in protection against erosion for river and coastal banks and marine and hydraulic construction

Geosynthetic products offer owners, engineers, and contractors a safe and economical solution to everyday engineering challenges and construction requirements. Used as replacements to natural materials, geosynthetic products include a wide range of functions such as filtration, drainage, separation and reinforcement requirements. The wide range of geosynthetic use includes landfill caps and base liner applications, environmental protection under roads and railways, containment structures, dams, canals, ponds, rivers and lakes, coastal and offshore protection. However, their potential in other applications is only limited by convention. With the use of geosynthetics, most geotechnical structures can be improved and the design lifetime can be dramatically increased. Additionally new modern design approaches are often only possible with the use of geosynthetics. Because of the strong development of the various industries all around the world the development and challenge of the use of geosynthetics in geotechnical, hydraulic, coastal and offshore engineering should be of special interest. Based on engineering approaches and installed projects, this paper will cover the state-of-the-art of geosynthetics use in environmental applications, as well as in hydraulic, coastal protection and offshore engineering structures and also discuss the benefits of geosynthetics to modern building technology.     

Biological effects of diethylene glycol (DEG) and produced waters (PWs) released from offshore activities: A multi-biomarker approach with the sea bass Dicentrarchus labrax

Diethylene glycol (DEG) is largely used during oil and gas exploitation by offshore platforms. The aim of this work was to investigate if this compound induces direct molecular/cellular effects in marine organisms, or indirectly modulate those of produced waters (PWs). Sea bass (Dicentrarchus labrax) were exposed to DEG dosed alone or in combination with PWs from an Adriatic platform. A wide array of analysed biomarkers included cytochrome P450-dependent enzymatic activity, bile metabolites, glutathione S-transferases, acetylcholinesterase, peroxisomal proliferation, antioxidant defences (catalase, glutathione reductase, glutathione peroxidases, glutathione), total oxyradical scavenging capacity, malondialdehyde and DNA integrity (single strand breaks and frequency of micronuclei). Results did not reveal marked effects of DEG, while PWs influenced the biotransformation system, the oxidative status and the onset of genotoxic damages. Co-exposures caused only limited differences of biomarker responses at some experimental conditions, overall suggesting a limited biological impact of DEG at levels normally deriving from offshore activities.     

Modelling of pitting corrosion in marine and offshore steel structures – A technical review

Corrosion is a major cause of structural deterioration in marine and offshore structures. It affects the life of process equipment and pipelines, and can result in structural failure, leakage, product loss, environmental pollution and the loss of life. Pitting corrosion is regarded as one of the most hazardous forms of corrosion for marine and offshore structures. The total loss of the structure might be very small, but local rate of attack can be very large and can lead to early catastrophic failure. Pitting corrosion is a localized accelerated dissolution of metal that occurs as a result of a breakdown in the protective passive film on the metal surface. It has been studied for many years; however, the structural failure due to pit characteristics is still not fully understood. Accurate pit depth measurements, precise strength assessment techniques, risk analysis due to pitting, and the mathematical relationship of the environmental factors that causes pitting failure are also factors, which need further understanding. Hence this paper focuses on these issues. It reviews and analyses the current understanding of the pitting corrosion mechanism and investigates all possible factors that can cause pitting corrosion. Furthermore, different techniques employed by scientists and researchers to identify and model the pitting corrosion are also reviewed and analysed. Future work should involve an in-depth scientific study of the corrosion mechanism and an engineering predictive model is recommended in order to assess failure, and thereby attempt to increase the remaining life of offshore assets.     

Fuzzy risk assessment of oil and gas offshore wells

Risk evaluation of offshore wells is a challenging task, given that much of the available data is highly uncertain and vague, and many of the mechanisms are complex and difficult to understand. Consequently, a systematic approach is required to handle both quantitative and qualitative data as well as means to update existing information when new knowledge and data become available. Each Basic Risk Item (BRI) in a hierarchical framework is expressed as a fuzzy number, which is a combination of the likelihood of a failure event and the associated failure consequence. Analytical Hierarchy Process (AHP) is used to estimate weights required for grouping non-commensurate risk sources. Evidential Reasoning (ER) is employed to incorporate new data for updating existing risk estimates. It is envisaged that the proposed approach could serve as a basis for benchmarking acceptable risks in offshore wells.