scholarly journals Contradictory Conclusions Surrounding the Effects of Chemical Dispersants on Oil Biodegradation

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Kelly M. McFarlin ◽  
Roger C. Prince
Keyword(s):  
Experimental Design ◽  
Breaking Waves ◽  
Microbial Colonization ◽  
Negative Effects ◽  
Neutral Buoyancy ◽  
Dispersed Oil ◽  
Oil Biodegradation ◽  
Oil Spill Response ◽  
Media Storage ◽  
Scientific Questions

ABSTRACT Dispersed oil has now been shown to have a ‘half-life’ of 10–30 days in numerous lab and field-based experiments. On the other hand, the biodegradation of floating oil slicks is much slower, and unless dispersed by heavy weather or the addition of chemical dispersants, spilled oil will likely strand on a shoreline where it may persist for years. Dispersants are designed to mix into the oil to lower the interfacial tension between the oil and the seawater, allowing even minor turbulence to generate small droplets that have essentially neutral buoyancy. Whether droplets are generated by breaking waves in the absence of added dispersants, or by much less turbulence after dispersant application, the enormous volume of seawater available for dilution impedes the coalescence of the droplets. Droplet formation stimulates biodegradation by dramatically increasing the oil surface area for microbial colonization. Even though the majority of peer-reviewed literature strongly indicates that chemical dispersants have minimal effects once oil is dispersed, a sub-set of publications report negative effects of dispersants on microorganisms and oil biodegradation. It is likely that differences in experimental design and expectations have led to different conclusions regarding the effects of dispersants. As interest in oil spill response grows throughout the scientific community, it is important to understand how similar scientific questions have led to varying conclusions. Here we highlight the importance of experimental design and how the use of specific methods can produce apparently contradictory results. Various methods from numerous publications involving the fate of undispersed oil and dispersed oil will be compared and contrasted. We will focus on specific details of experimental design that impact the results and conclusions of various oil biodegradation studies, such as temperature, concentration, media storage, and substrate handling. An emphasis will be placed on experimental relevance and challenges associated with replicating real world phenomena in the laboratory.

Mobilizing for Some

2016 ◽  
Vol 28 (3) ◽  
pp. 123-135 ◽  
Author(s):  
Raffael Heiss ◽  
Jörg Matthes
Keyword(s):  
High School ◽  
Social Media ◽  
High School Students ◽  
Experimental Design ◽  
Collective Efficacy ◽  
Political Efficacy ◽  
Negative Effects ◽  
School Students ◽  
Positive Effects ◽  
Specific Factors

Abstract. This study investigated the effects of politicians’ nonparticipatory and participatory Facebook posts on young people’s political efficacy – a key determinant of political participation. We employed an experimental design, using a sample of N = 125 high school students (15–20 years). Participants either saw a Facebook profile with no posts (control condition), nonparticipatory posts, or participatory posts. While nonparticipatory posts did not affect participants’ political efficacy, participatory posts exerted distinct effects. For those high in trait evaluations of the politician presented in the stimulus material or low in political cynicism, we found significant positive effects on external and collective efficacy. By contrast, for those low in trait evaluations or high in cynicism, we found significant negative effects on external and collective efficacy. We did not find any effects on internal efficacy. The importance of content-specific factors and individual predispositions in assessing the influence of social media use on participation is discussed.

scholarly journals Effects of Dispersants and Biosurfactants on Crude-Oil Biodegradation and Bacterial Community Succession

2021 ◽  
Vol 9 (6) ◽  
pp. 1200
Author(s):  
Gareth E. Thomas ◽  
Jan L. Brant ◽  
Pablo Campo ◽  
Dave R. Clark ◽  
Frederic Coulon ◽  
...  
Keyword(s):  
Crude Oil ◽  
Early Stage ◽  
Niche Partitioning ◽  
Hydrocarbon Biodegradation ◽  
Hydrocarbonoclastic Bacteria ◽  
Bacterial Response ◽  
Oil Biodegradation ◽  
Interfacial Surface ◽  
Degrading Bacteria ◽  
Oil Spill Response

This study evaluated the effects of three commercial dispersants (Finasol OSR 52, Slickgone NS, Superdispersant 25) and three biosurfactants (rhamnolipid, trehalolipid, sophorolipid) in crude-oil seawater microcosms. We analysed the crucial early bacterial response (1 and 3 days). In contrast, most analyses miss this key period and instead focus on later time points after oil and dispersant addition. By focusing on the early stage, we show that dispersants and biosurfactants, which reduce the interfacial surface tension of oil and water, significantly increase the abundance of hydrocarbon-degrading bacteria, and the rate of hydrocarbon biodegradation, within 24 h. A succession of obligate hydrocarbonoclastic bacteria (OHCB), driven by metabolite niche partitioning, is demonstrated. Importantly, this succession has revealed how the OHCB Oleispira, hitherto considered to be a psychrophile, can dominate in the early stages of oil-spill response (1 and 3 days), outcompeting all other OHCB, at the relatively high temperature of 16 °C. Additionally, we demonstrate how some dispersants or biosurfactants can select for specific bacterial genera, especially the biosurfactant rhamnolipid, which appears to provide an advantageous compatibility with Pseudomonas, a genus in which some species synthesize rhamnolipid in the presence of hydrocarbons.

scholarly journals Gas exchanges in sugar apple (Annona squamosa L.) subjected to salinity stress and nitrogen fertilization

2019 ◽  
pp. 1959-1966
Author(s):  
Francisco Romário Andrade Figueiredo ◽  
Anderson Carlos de Melo Gonçalves ◽  
João Everthon da Silva Ribeiro ◽  
Toshik Iarley da Silva ◽  
Jackson Silva Nóbrega ◽  
...  
Keyword(s):  
Experimental Design ◽  
Gas Exchange ◽  
Chlorophyll Content ◽  
Irrigation Water ◽  
Nitrogen Fertilization ◽  
Annona Squamosa ◽  
Negative Effects ◽  
Chlorophyll Content And Fluorescence ◽  
Fluorescence Parameters ◽  
Salinity Levels

Salinity is one of the modern agriculture major obstacles, causing several physiological disturbances in plants, adversely affecting its growth and development. Therefore, some techniques are required in order to alleviate the negative effects of salinity stress on plants, as for example an adequate nitrogen fertilization. The aim of this study was to assess the ecophysiological responses of sugar apple plants (Annona squamosa L.) submitted to different salinity levels and nitrogen fertilization doses. The experimental design was a randomized block in an incomplete factorial scheme, with five electrical conductivities of the irrigation water (ECw: 0.5, 1.01, 2.25, 3.49 and 4.0 dS m-1) and five nitrogen doses (0, 101, 350, 598.2 and 700 mg dm-3), with four replicates, generated from the Box Central Composite experimental design matrix. Through a daily course, it was observed variations in gas exchange, chlorophyll content and fluorescence parameters. The gas exchange, chlorophyll content and fluorescence parameters were measured on photosynthetically active leaves. There was significant interaction between the salinity levels (ECw) and nitrogen doses for the chlorophyll indexes. The electrical conductivity of the irrigation water caused significant negative effects on chlorophyll fluorescence. Therefore, it can be stated that the sugar apple plants ecophysiology varies through the day and that salinity affects its chlorophyll content and fluorescence.

Competition in Plant Communities

Ecology ◽  
2012 ◽  
Author(s):  
Paul A. Keddy ◽  
James Cahill
Keyword(s):  
Experimental Design ◽  
Plant Communities ◽  
Managed Forests ◽  
Negative Effects ◽  
Large Numbers ◽  
Multiple Species ◽  
Choice Of Species ◽  
Intensity Of Competition ◽  
Plant Coexistence ◽  
Growth And Reproduction

Competition is generally understood to refer to the negative effects on plant growth or fitness caused by the presence of neighbors, usually by reducing the availability of resources. Competition can be an important factor controlling plant communities, along with resources, disturbance, herbivory, and mutualisms. Since all plants require a few basic elements, the resource involved is generally light, water, nitrogen, or phosphorus, depending upon the species and the location. The effects of competition are widespread and easily observed in mixtures of crops and managed forests, which is why weeding and thinning are practiced. Competition is also widespread in native habitats, from deserts to wetlands, and is known to have important—indeed crucial—effects upon recruitment, growth, and reproduction. In the late 1800s, Darwin wrote extensively about the importance of competition in nature, particularly its role in driving natural selection. Thereafter, interest in the phenomenon grew. Many experiments with both crops and wild species were conducted. Models of competitive interactions were also constructed, with the number and size of the models increasing rapidly with the advent of computers in the 1970s. Because the word competition has a common usage in English, what it represents in biological systems is frequently assumed, rather than explicitly stated, leading to misunderstanding. Care must be taken in using or interpreting the word without specifying what kind of competition is being investigated, as different forms of competition can have different types of consequences. For example, competition may be looked at from the perspective of an individual, a population, or a species, it may be symmetric or asymmetric, and it can occur among single or multiple species simultaneously. Experimental design carries its own assumptions, which are often not stated in published articles. One of the most difficult tasks in exploring published studies is the need to sift through large numbers of experiments in which investigators have haphazardly selected (a pair of) species and grown them in mixture, without adequately justifying their choice of species or the experimental design. Another difficult task is distinguishing between models that, at least in principle, have measurable inputs or make measurable predictions (or both) and those that do not and cannot be tested. Overall, the very ease of growing plants in mixture, as well as the ease of making new models, may have made some people careless, with the result that basic questions are remaining unaddressed. Ongoing issues of importance include mechanisms of competition, types of competition, effects of competition on plant coexistence, and the intensity of competition under different sets of conditions.

scholarly journals Staphylococcus aureus Exotoxins and Their Detection in the Dairy Industry and Mastitis

Toxins ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 537 ◽  
Author(s):  
Ana G. Abril ◽  
Tomás G. Villa ◽  
Jorge Barros-Velázquez ◽  
Benito Cañas ◽  
Angeles Sánchez-Pérez ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Dairy Industry ◽  
Food Poisoning ◽  
Microbial Colonization ◽  
Economic Losses ◽  
Human Consumption ◽  
Negative Effects ◽  
Virulence Proteins ◽  
Causative Agents ◽  
Best Medical Therapy

Staphylococcus aureus constitutes a major food-borne pathogen, as well as one of the main causative agents of mastitis in dairy ruminants. This pathogen can produce a variety of extracellular toxins; these include the shock syndrome toxin 1 (TSST-1), exfoliative toxins, staphylococcal enterotoxins (SE), hemolysins, and leukocidins. S. aureus expresses many virulence proteins, involved in evading the host defenses, hence facilitating microbial colonization of the mammary glands of the animals. In addition, S. aureus exotoxins play a role in the development of both skin infections and mastitis. Indeed, if these toxins remain in dairy products for human consumption, they can cause staphylococcal food poisoning (SFP) outbreaks. As a result, there is a need for procedures to identify the presence of exotoxins in human food, and the methods used must be fast, sensitive, reliable, and accurate. It is also essential to determine the best medical therapy for human patients suffering from S. aureus infections, as well as establishing the relevant veterinary treatment for infected ruminants, to avoid economic losses in the dairy industry. This review summarizes the role of S. aureus toxins in the development of mastitis in ruminants, their negative effects in the food and dairy industries, and the different methods used for the identification of these toxins in food destined for human consumption.

Effect of Dispersants on Oil Biodegradation Under Simulated Marine Conditions

1999 ◽  
Vol 1999 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Richard P. J. Swannell ◽  
Fabien Daniel
Keyword(s):  
Crude Oil ◽  
Cluster Formation ◽  
Hydrocarbon Biodegradation ◽  
Dispersed Oil ◽  
Oil Biodegradation ◽  
Size Number ◽  
Degrading Bacteria ◽  
Aliphatic And Aromatic Hydrocarbons ◽  
Micro Organisms ◽  
Neutrally Buoyant

ABSTRACT A study was undertaken on the dispersion, microbial colonisation and biodegradation of chemically-dispersed weathered Forties crude oil under simulated marine conditions in laboratory microcosms. The measurements of droplet size, number and microbial colonisation were made using new techniques developed by the project team. Rapid growth of indigenous micro-organisms capable of degrading both crude oil and dispersants was observed in the presence of chemically-dispersed oil. These organisms colonised the dispersed oil and biodegraded the aliphatic and aromatic hydrocarbons. These processes was stimulated by the addition of inorganic nutrients. Some colonised droplets agglomerated into neutrally-buoyant “clusters” (100 µm- 2 mm diameter) consisting of oil, bacteria, protozoa, and nematodes. After substantial hydrocarbon biodegradation these clusters sank to the bottom of the microcosms. No biodegradation or cluster formation was noted in “killed” controls in which biological activity had been inhibited. Different dispersants promoted microbial growth to differing extents. These results suggest that the addition of dispersants can increase the rate of oil biodegradation under natural conditions by promoting the growth of indigenous hydrocarbon-degrading bacteria, as well as increasing the surface area of oil available for microbial colonisation.

In Situ Oil Spill Countermeasures in Ice-Infested Waters: A Modeling Study of the Fate/Behaviours of Spilled Oil

2014 ◽  
Vol 2014 (1) ◽  
pp. 1215-1225 ◽  
Author(s):  
Haibo Niu ◽  
Kenneth Lee ◽  
Michel C. Boufadel ◽  
Lin Zhao ◽  
Brian Robinson
Keyword(s):  
Oil Spill ◽  
Oil And Gas ◽  
Arctic Region ◽  
The Arctic ◽  
Oil Transport ◽  
Habitat Recovery ◽  
Dispersed Oil ◽  
Oil Biodegradation ◽  
Arctic Conditions ◽  
Spilled Oil

ABSTRACT The expansion of offshore oil and gas and marine transport activities in the Arctic have raised the level of risk for an oil spill to occur in the Arctic region. Existing technologies for oil spill cleanup in ice-covered conditions are limited and there is a need for improved oil spill countermeasures for use under Arctic conditions. A recent field study has assessed a proposed oil spill response technique in ice-infested waters based on the application of fine minerals in a slurry with mixing by propeller-wash to promote the formation of oil-mineral aggregates (OMA). While it was verified in the experimental study that the dispersion was enhanced and mineral fine additions promoted habitat recovery by enhancing both the rate and extent of oil biodegradation, limited monitoring data provide little insights on the fate of dispersed oil after the response. To help understand the oil transport process following mineral treatment in ice-covered conditions, mathematical modeling was used in this study to simulate the transport of OMA and calculate the mass balances of the spilled oil. To study the effects of ice and minerals on the fate and transport, the result was compared with scenarios without ice and without the addition of mineral fines. The results show general agreement between the modeling results and field observations, and further confirm the effectiveness and potential for using mineral treatment as a new oil spill counter-measure technology. This technique offers several operational advantages for use under Arctic conditions, including reduced number of personnel required for its application, lack of need for waste disposal sites, and cost effectiveness.

Dispersant-Related Oil Spill Response Communication Tools: Toward an Enhanced Approach to Conveying Complex Topics in an Approachable Manner

2014 ◽  
Vol 2014 (1) ◽  
pp. 1163-1171
Author(s):  
Thomas Coolbaugh ◽  
Erik DeMicco ◽  
Emily Kennedy
Keyword(s):  
Oil Spill ◽  
Extensive Study ◽  
Optimal Decision ◽  
Specific Response ◽  
Negative Effects ◽  
Response Options ◽  
The Public ◽  
Scientific Principles ◽  
Oil Spill Response ◽  
Informed Opinion

ABSTRACT During the response to the Macondo Well release in the Gulf of Mexico in 2010, it became evident fairly quickly that there was a potential disconnect between existing scientifically-based information relating to the use of oil spill dispersants and the information that was readily available to the general public, the media, and government officials. At best, both sets of information were aligned and provided a valuable perspective to those who sought an increased understanding of the workings of oil spill response tools. At worst, there was a large misalignment and the information that was available to the public did not accurately reflect the known science of what dispersants have been designed to achieve. In this latter case, conclusions about dispersant use may have been formed incorrectly, providing a backdrop upon which individuals were not able to develop an informed opinion regarding the use of dispersants. In the case where incomplete and potentially unbalanced information is used to inform the public, it is possible that negative effects will result, i.e., opinions may be formed based on fear of the unknown, causing a delayed or less than optimal decision making process. While it is recognized that decisions made during a spill response may be challenging and may involve an environmental trade-off, an informed public can be a valuable asset during the stages of an emergency response when the pros and cons of the specific response options are being debated. To assist with an informed dialog, it is important to have materials available that accurately reflect the scientific principles upon which they are based, but without requiring extensive study of their details for a general understanding of their primary assumptions and conclusions. This paper summarizes recent efforts to develop readily available materials that can provide a better understanding of the use of dispersants during an offshore oil spill response. These efforts have been focused on developing simple yet effective tools which describe dispersants within the framework of an oil spill response tool box and the scenarios in which these tools may be used for the most positive environmental effect.

Oil Spill Dispersants

1999 ◽  
Vol 71 (1) ◽  
pp. 27-42 ◽  
Author(s):  
Robert J. Fiocco ◽  
Alun Lewis
Keyword(s):  
Oil Spill ◽  
Oil Spills ◽  
Environmental Damage ◽  
Limited Extent ◽  
Practical Application ◽  
Naturally Occurring ◽  
Dispersed Oil ◽  
Application Techniques ◽  
Oil Spill Response ◽  
Oil Spill Dispersants

Introduction: The purpose of any oil spill response is to minimise the damage that could be caused by the spill. Dispersants are one of the limited number of practical responses that are available to respond to oil spills at sea.When oil is spilled at sea, a small proportion will be naturally dispersed by the mixing action caused by waves. This process can be slow and proceed to only a limited extent for most situations. Dispersants are used to accelerate the removal of oil from the surface of the sea by greatly enhancing the rate of natural dispersion of oil and thus prevent it from coming ashore. Dispersed oil will also be more rapidly biodegraded by naturally occurring microorganisms. The rationale for dispersant use is that dispersed oil is likely to have less overall environmental impact than oil that persists on the surface of the sea, drifts and eventually contaminates the shoreline. The development of modern dispersants began after the Torrey Canyon oil spill in 1967. Many lessons have been learned since that spill, and consequently the modern dispersants and application techniques in use today have become an effective way of responding to an oil spill. For example, the dispersant response to the Sea Empress spill in 1996 demonstrated that dispersants can be very effective and prevent a much greater amount of environmental damage from being caused (6). This chapter describes the chemistry and physics of dispersants, planning and decision-making considerations, and finally their practical application and operational use in oil spill response.

scholarly journals THE INFLUENCE OF HUMIC ACIDS IN THE PRESENCE OF OIL-DEGRADING MICROORGANISMS OF THE GE-NUS RHODOCOCCUS ON THE SOWING QUALITIES OF COCKWEED IN OIL POLLUTION

2020 ◽  
pp. 291-298
Author(s):  
Mariya Mikhaylovna Gertsen ◽  
Elena Dmitrievna Dmitrieva
Keyword(s):  
Humic Acids ◽  
Oil Pollution ◽  
Complete Removal ◽  
Negative Effects ◽  
Oil Biodegradation ◽  
Test Culture ◽  
High Moor ◽  
Resistance To Stress ◽  
Positive Effect ◽  
High Moor Peat

By the method of biotesting, it has been established that the addition of oil-degrading microorganisms of the genus Rhodococcus to the soil contaminated with hydrocarbonshas a positive effect on morphogenesis and sowing qualities of the cockweed test culture, which is associated with the microbiological oxidation of oil by bacteria of the studied strains. It was revealed that a positive effect was observed in 5 of 8 variants of the experiment on the medium with hexadecane with the joint introduction of humic acids and microorganisms. Under the conditions of oil pollution, the introduction of Rh. erythropolis X5 and Rh. erythropolis S67 microorganisms into the substrate with the addition of humic acids as a whole has a stimulating effect on the morphogenesis and sowing qualities of cockweed. It should be noted that it was in the “oil + humic acids + microorganism” variant that the indicators were obtained that maximally exceeded the values of the contaminated control. Reducing the toxicity of oil and hexadecane, and in some cases, the complete removal of the negative effects of toxicants in the relation to the test culture are apparently connected with the intensification of the process of oil biodegradation due to the stimulating effect of humic acids on the microorganisms. It is proved that the introduced humic acids act as adaptogens in the relation to the microorganisms Rh. erythropolis X5 and Rh. erythropolis S67, increasing their resistance to stress loads under conditions of oil stress. Thus, the results show that the introduction of humic acids can contribute to more effective biodegradation of oil pollution of soils. At the same time, in order to increase the efficiency of humic acids, the use of humic acids of sphagnum transitional peat + Rh.erythropolis X5, humic acids of sphagnum high-moor peat + Rh. erythropolis X5, humic acids of reed fen peat + Rh. erythropolis S67 in the conditions of oil pollution seems more promising. On a substrate with hexadecane, it is advisable to consider the use of humic acids of sphagnum high-moor peat, because in this variant, the parameters that maximally exceed the contaminated control were noted.

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