Oil Spills-Where We Were, Where We Are, And Where We Will Be? A Bibliometric and Content Analysis Discourse

. More frequently and in more ways than one might think, oil spills are a very common phenomenon. There were three major (>700 tonnes; Asia and Africa) and four minor oil spills only in 2022 (between 7 and 700 tonnes; North America, Asia, and Africa). Oil spills have been known to cause numerous negative ecological, societal, economic, and public health impacts. Not only this but oil spills require rapid response to contain and mitigate multidimensional damages caused. A SCOPUS search of the keyword ‘Oil Spills’ in ‘’Article title, Abstracts, and Keywords’ and ‘Article title’ results in 30529 and 9851 (as of March 4 th , 2023) documents (Journal articles, Conference proceedings, Books, Book series, Trade journals, and Reports). In the year 2023 alone, the SCOPUS database had 297 documents at the time of writing. Such a massive database requires a retrospection of underlying and emerging themes for readers to understand the extant literature and to uncover future research agendas. This study is an attempt to conduct a bibliometric analysis of select ‘Oil spill’ publications. This investigation will involve performance analysis (performance of research constituents such as publication and citation evolution, leading authors, publications, affiliations, sources, and countries) and science mapping (relationship between research constituents by analyzing conceptual, intellectual, and social structures). VOSviewer and Biblioshiny The study will conclude future research trends by the content analysis of the fifteen most recent and cited documents.


Introduction
Any accidental or intentional discharge of a liquid petroleum hydrocarbon into the environment is known as an oil spill.These spills, which could occur on land or in bodies of water like rivers, lakes, or oceans, can be very harmful to the environment, animals, and people's health.Since biological productivity is greater in shorelines or coasts and oil stranded on shorelines may stay for a long time, the issue is made worse if spilled oil reaches these shorelines or coast 6 .
In line with ITOPF, three major spills (more than 700 tonnes) and four moderate accidents (between 7 and 700 tonnes) were reported during the year 2022.One spill in Africa and two major spills in Asia.The medium spills occurred in North America, Asia, and Africa.With this, the decade average now stands to over 6 spills (>7 tonnes) annually.This is equivalent to the 2010s average.In 2022, the total amount of oil lost to the environment due to tanker spills was roughly 15,000 tonnes.The three significant incidents are responsible for almost 14,000 tonnes of oil spills thereby polluting the environment.Oil may also pollute soil and groundwater, making agricultural production or other uses problematic.Preventing spills is therefore the best course of action.The size of the worldwide market for oil spill management is expected to increase at a compound annual growth rate (CAGR) of 3.5% between 2023 and 2030, with current estimates of USD125.6 billion.Over the next nine years, the worldwide market is anticipated to be driven by increased safety concerns as well as an increase in the number of oil spill occurrences throughout the world in recent years.Despite best attempts, however, oil spills continue to occur, emphasizing the need for ongoing studies and developments in this area.Through bibliometric analysis, this research critically investigates the pattern of publications on the subject of oil spills that are published by the most highly cited and prominent authors as well as the contribution of developed and developing nations and their associated institutions and thematic evolution.The article also provides a thorough analysis of several control and monitoring methods for avoiding oil spills and remedies for them.A keyword search of 'Oil Spills' in the 'Article Title' option of SCOPUS alone results in 9935 publications (April 15, 2023).Along with 17,143 total publications (and 9996 only WOS publications) extracted from WOS (April 15, 2023), this extraordinarily large dataset is far beyond the limits of systematic reviews and other review techniques.Since bibliometric analysis can handle , 01050 (2024) BIO Web of Conferences https://doi.org/10.1051/bioconf/2024860105086 RTBS-2023  extraordinarily large datasets as compared to systematic reviews, this bibliometric research approach could help researchers, students, and practitioners all over the world to assimilate the past and present of 'Oil spills' research along with exploration of future avenues of research in this area.Moreover, as in bibliometric investigations, the central stage is taken up by bibliometric data which is highly objective and is blended with the authors' logical subjectivity, bibliometric investigation was preferred over systematic reviews which are more subjective and hence sometimes believed to be suffering from authors' bias.A search of "Bibliometric analysis" and "Oil Spills" in the "Article Title" search option of SCOPUS and WoS resulted in seven publications.Two of these seven publications namely "Bibliometric Analysis of Accidental Oil Spills in Ice-Infested Waters" 54 and "Bibliometric Analysis of Research Hotspots Related to Marine Oil Spill Accidents in the Environmental Field" 119 specifically were found to focus on bibliometric research inquiries on "Accidental Oil Spills".The third publication titled "Oil spill detection and Mapping: A 50-year bibliometric analysis" 109 focused on 'Oil spill detection and mapping'.Two publications titled "Bioremediation of Diesel Contaminated Marine Water by Bacteria: A Review and Bibliometric Analysis" 56 and "Bibliometric Analysis of Hydrocarbon Bioremediation in Cold Regions and a Review on Enhanced Soil Bioremediation" 123 were found very specifically covering aspects of 'Bioremediation'.The remaining two publications; 'A Review and Bibliometric Analysis on Applications of Microbial Degradation of Hydrocarbon Contaminants in Arctic Marine Environment at Metagenomic and Enzymatic Levels' 111 and 'Bibliometric Analysis of Research on Diesel Pollution in Antarctica and a Review on Remediation Techniques' 63 were region specific (arctic and Antarctica).Bibliometric investigations help uncover the performance of and relationship between research constituents on a broad level 29 .Research areas specific to any topic are usually addressed using either systematic literature reviews or are made part of a set of research questions under bibliometric investigations.This research, therefore, differentiates itself from existing systematic literature reviews and bibliometric investigations by providing a holistic and objective retrospection of the literature on 'Oil Spills'.This bibliometric investigation, therefore, tries to address the undermentioned broad research questions pertaining to Oil Spills literature:

Procurement of Articles for Bibliometric Analysis
SCOPUS and WOS were used to retrieve 9935 and 9996 publications by searching for specific keywords and their combinations in the database's article title, and relevant keywords search options.VOSviewer and the R-based tool Biblioshiny were used to perform bibliometric analysis.Because of the study's emphasis on conducting performance analysis, science mapping, exploration of contemporary and sustainable oil spill treatment techniques, it was essential to select only relevant publications that could help achieve stated outcomes, articles were selected using the Preferred Reporting Items for the Systematic Review template 71 .Figure 1 presents an adapted schema of the PRISMA process utilized for publications selection and a snapshot of the methodology: By the end of the process, bibliometric analysis was employed on 951 publications that were chosen for further investigation after having been analyzed to meet the goals of this investigation.Two primary methods, performance analysis, and scientific mapping proposed by Noyons et al. (1999) were employed for these outcomes as discussed below:

Performance analysis
Performance analysis 23,91 gazes at how individual publications, researchers, and institutions have impacted a certain topic.Various metrics are used for performance analysis, with most of them having to do with tracking the performance of research constituents 69 such as publication and citation overview, most cited publications, authors, sources, and countries.

Scientific Mapping
Through the use of science mapping, one can gain acquaintance with the emerging themes in the intellectual, social, and conceptual frameworks of a knowledge corpus and its progressive changes over time 24 .In this investigation, the major conceptual frameworks pertaining to oil spills were captured by keyword co-occurrence analysis.Mainstream literature (past but significant knowledge body) with its theoretical underpinnings was determined using co-citation analysis, current areas of research were mined using bibliographic coupling of documents, and underlying themes and potential areas for future research were unearthed using a thematic map, which is displayed by exhibiting clusters in a bi-dimensional grid with density and centrality as two axes.Future research hot spots identified using thematic map were supplemented with a content analysis of recent and highly cited research publications (2020-2023).A co-authorship analysis was also performed to understand the intellectual structure (the author collaborations) 85 .The social structure of oil spill literature was determined by country collaboration analysis.

Analysis and discussion of results
This section builds upon the performance analysis and science mapping coupled with content analysis to accomplish RQ3 (exploring contemporary and sustainable oil spill clean-up techniques) and to supplement the results of RQ4 (identification of Hot spots for future research).The publication overview clearly shows four peaks; 2006 (TP=13, MCA=110), 2008 (TP=21, MCA=21.95), 2017 (TP=87, MCA=27.78) and 2021 (TP=112, MCA=7.12).The major focus of publications in 2006 (first peak) was to determine the impact of salinity on the dispersion of oil spills 19 , concentrations of polycyclic aromatic hydrocarbons (PAH) in the wild mussels (Mytilus galloprovincialis), and their fluctuation over time due to oil spills 76 to name a few.The focus shifted to themes such as Oil weathering at a marine seep using GCxGC and Petroleum biodegradation 115 , classification of alkanes, hopanes, and polycyclic aromatic hydrocarbons 20, and oil exploration's destructive effects on Nigeria's, efforts to preserve the region's unique ecology 106 in the year 2008 (second peak).The third peak in the year 2017 witnessed publications focusing on deepwater oil spills 22 and areas such as deepwater oil spill response and clean-Up 61 , Hazards, Extenuation Priorities, and State Reporting Requirements for unconventional oil spills 81 , and bioremediation to name a few 14  Peak four (2021) was populated by publications trying to detect marine oil spills using methods such as Synthetic Aperture Radar over the Indian Ocean 73 , sensors, image transformation methods, and mapping 131

Most Influential Publications
Since the impact of a publication can be directly measured by the number of citations it receives, the most influential publications in the dataset that influenced the writers working on 'Oil Spills' globally were identified and extracted accordingly.Table 1 illustrates the most cited publications in the dataset: With 579 citations (TC=579), "Oil biodegradation and bioremediation: A tale of the two worst spills in U.S. history", authored by Atlas and Hazen (2011) was the most influential publication in the dataset.Focusing on the upsetting ecological impacts of the Exxon Valdez spill (1989) and the BP Deepwater Horizon spill (2010), this publication suggested employing the biological pathways inside microbes or plants engaged in the bioremediation of oil spills as an effective method to treat oil spills."Aryl hydrocarbon receptor-independent toxicity of weathered crude oil during fish development" (TC=282) authored by Incardona, Carls, Teraoka, Sloan, Collier., and Scholz (2005) was the second most influential publication.This study employed antisense morpholino oligonucleotides to inhibit components of the AhR (aryl hydrocarbon receptor) pathway, and the results demonstrated that lowmolecular-weight tricyclic PAHs were mainly accountable for the major defects in development caused by exposure to weathered crude oil.The results of this study thus suggested many implications to assess the impact of Polycyclic aromatic hydrocarbons (PAHs) on coastal habitats.The detailed analysis of the ten most influential publications has been tabulated below in Table 2. To study the molecular, genetic, and developmental implications of the Deepwater Horizon oil spill on Gulf Killifish.
The expression of genes linked to stress response, metabolism, and development were all found to be altered by the oil spill.Fish had other morphological abnormalities, like shrunken bodies and altered liver and gill structures.

"Global Gray Water Footprint and Water Pollution Levels Related to Anthropogenic Nitrogen Loads to Fresh Water"
To learn more about the worldwide connection between greywater footprint, water pollution, and anthropogenic nitrogen loads to freshwater sources.
The study found that a considerable proportion of the nitrogen load was not appropriately processed and discharged into the environment, as indicated by the high correlation between the greywater footprint and nitrogen pollution levels discovered by the researchers.

6
"Coastal and environmental remote sensing from unmanned aerial vehicles: An overview" The purpose of the research was to examine how UAVs can be used for ecological monitoring and management in diverse contexts, such as detecting coastal erosion, tracking biodiversity, detecting changes in land use and land cover, and checking water quality.
The study participants believed that UAVs' high spatial resolution, adaptability, and low cost were significant benefits over more conventional remote sensing methods.
, The aim of this article was to give readers an overview of the present state of ecosystem restoration activities.
The participation of local people and stakeholders, as well as the establishment of effective monitoring and assessment mechanisms, are essential for successful ecosystem restoration and reconstruction initiatives.Insufficient resources, a lack of political will, and a lack of understanding of ecological processes are all hindrances to restoration and rehabilitation efforts.

8
"Next-generation sequencing of microbial communities in the Athabasca River and its tributaries in relation to oil sands mining activities" The purpose of this study was to determine the diversity and quantity of microorganisms in the Athabasca River and its tributaries and to investigate the effects of oil and mining on these communities.
Oil sand mining has the potential to negatively affect microbial communities, however, this study found multiple microbial species with the potential to break down hydrocarbons, suggesting that bioremediation may be an effective technique for reducing these negative effects.

9
"Polycyclic aromatic hydrocarbon (PAHs) and hopanes in stranded tarballs on the coasts of Peninsular Malaysia: Applications of biomarkers for identifying sources of oil pollution" Using biomarkers such as polycyclic aromatic hydrocarbons (PAHs) and hopanes, researchers hope to pinpoint the origins of oil pollution off Peninsular Malaysia's coasts.
This research showed how biomarkers like polycyclic aromatic hydrocarbons (PAHs) and hopanes might be used to trace oil pollution back to its origins and better direct management and prevention strategies.

10
"Analysis of eight oil spill dispersants using rapid, in vitro tests for endocrine and other biological activity" The purpose of this study was to evaluate the eight dispersants for their impact on biological pathways like oxidative stress and cytotoxicity, as well as the function of estrogen, androgen, and glucocorticoid receptors.
There may be consequences for human and ecological health from using oil spill dispersants due to the possibility of unanticipated effects on endocrine and other biological mechanisms.

Most Relevant Authors
The relevance of authors can be determined based on productivity and impact.While the productivity of authors is measured by the number of papers they produced in a specified time frame, the impact of authors can be measured using the number of citations that publications contributed by them receive over a period of time.Working in the same direction, the most relevant authors in the dataset were identified and have been presented below in Tables 3a and 3b:  Le Floch S was found to be the third most productive author (NP=16, AF=2.26).Evaluating the role of treated and untreated oil on fish's capacity to adapt to its environment (2013), evaluating the role of dispersants on the environment and nearshore habitats (2011), and contrasting the cost-benefit analysis of the use of dispersants in treating oil spills (2011) were some of the most influential works by Le Floch.
Reddy CM (NP=12, AF=2.12,Rank=4) on the list of most productive authors worked on characterizing the biological breakdown of long-lasting saturated hydrocarbons in Deepwater Horizon oil samples (2014) followed by Brakstad OG (NP=8, AF=1.90, Rank=5) who worked on surfactants' use to clean up oil spills break down in frigid water.The major contribution of Engel LS. (NP=13, AF=1.63,Rank=6) was evaluating the impacts of deepwater horizon Oil Spills.Murawski SA (NP=8, AF=1.51),Kwok RK (NP=12, AF=1.46)., Sandler DP (NP=11, AF=1.38), and Rouhani S (NP=8, AF=1.24) ranked 7,8, 9 and 10 on the list of most productive authors.Surprisingly, none of the authors on the list of the most productive authors were found to be on the list of the top 10 most impactful authors as evidenced by Table 3b.Hazen TC with 847 citations was found to be the most impactful author.His mainstream work revolved around employing the biological pathways inside microbes or plants engaged in the bioremediation of oil spills as an effective method to treat oil spills (2011).Valentine Dl (TC=838) was the second most influential author whose major work revolved around evaluating the fate of dispersants used to treat deepwater horizon oil spills (2011).Liu Z with 835 citations was the third most impactful author who worked on exploring the environmental and food safety issues in China due to oil spills and soil pollution.Li H was found to be the fourth most impactful author (TC=712) who contributed to simulating the toxicity of metal mixtures and hydrocarbons leading to environmental and health risks in China.
Lu Y (TC=706, Rank=5), Ferrier RC (TC=705, Rank=6), Jenkins A (TC=705, Rank=7), Luo W (TC=705, Rank=8), Meng J (TC=705, Rank=9), and Song S. (TC=705, Rank=10) on the list of most impactful authors had one paper in a collaboration that was one of the most impactful publications (Impacts of soil and water pollution on food safety and health risks in China) in the dataset (except Lu Y who had an additional publication with one citation).

Most Relevant Sources
The dataset consists of 187 journals that have published articles covering oil spills' environmental impact.This domain has been progressive over the years (Figure 2).To demonstrate the impact of journals, Tables 3a and 3b list the ten most relevant journals.In this analysis, the total number of publications and the total number of citations were used to categorize the most productive and most impactful sources respectively.With 118 publications in the dataset, "Marine Pollution Bulletin" was the most productive source followed by "Science of the Total Environment" (TP=61), "Environmental Science and Technology" (TP=41), "Ecotoxicology and Environmental Safety" (TP=30), "International Journal of Environmental Research and Public Health" (TP=29), "Environmental Pollution" (TP=27), "Chemosphere" (TP=27), "Frontiers in Marine Science" (TP=27), "Journal of Marine Science and Engineering" (TP=25), and "Applied and Environmental Microbiology" (TP=21).However only the third most productive journal (TP=41) with 3945 total citations, "Environmental Science and Technology" was found to be the most impactful source in the dataset.Interestingly, while not in the top ten productive sources list, sources like "Environment International", "Environmental Health Perspectives", "Marine Ecology Progress Series", and "Journal of Hazardous Materials" made their place in the list of the top ten most impactful sources with 929, 865, 531, and 526 citations respectively.

Country Publication Analysis
53 nations contributed to the publication of the 951 publications in the dataset under consideration.Table 5 shows the ten most productive countries to publish on oil spills.

Source: SCOPUS database and Author's Compilation; Note: TP-Total Publications
The top ten most productive countries contributed 651 (68.45%) publications in the dataset.As clear from Table 5, the USA was found to be the most productive country to publish on oil spills in the dataset (NP=273) followed by China (NP=95), Norway (NP=46), Canada (NP=45), the United Kingdom (NP=45), Spain (NP=44), France (NP=35), Brazil (NP=30), Germany (NP=20) and Finland (NP=18).Only two developing countries i.e., China (Rank-2, NP=95) and Brazil (Rank-8, NP=30) made it to the list of the top ten most productive nations to publish on oil spills while the rest all places belonging to developed countries indicating a very skewed publication productivity trend.

Co-Citation analysis
Co-citation helps determine the subject similarity of two research documents.When two research documents are cited together in a third document, they are said to be co-cited.The number of identical cited items defines the strength of co-citation between two documents.CO-citation strength can be measured as the degree of relationship or association between documents as perceived by the group of citing authors 103 .The co-citation analysis of cited authors is presented in Figure 3.The minimum no. of citation was kept at 7, only 21 authors met this criterion.
The network formed was based on 5 clusters.Cluster 1 and Cluster 2 were the largest clusters with 5 documents each.Cluster 1 highlights key research areas like post impact of deepwater horizon disaster 3,16 , biodegradation at the deepwater horizon 16 , and long-term ecosystem response to the oil spill 86 .Cluster 2 as represented in green color in Figure 3 corresponds to research areas like oil biodegradation and bioremediation 7 , genetic damage to aquatic animals, and marine toxicity 18,74,92 .Cluster 3 with 4 documents is represented by blue color in Figure 3 corresponds to research areas like the effect of dispersed crude oil on copepods and polycyclic aromatic hydrocarbon uptake by fishes 100,5,42 and environmental effects of the deepwater horizon oil spill 11 .Cluster 4 with 4 documents is represented in yellow color in Figure 3 corresponds to research areas like microbial degradation of petroleum hydrocarbons 108,60,43 and data collection method for ecotoxicity due to dispersed oil 77 .Cluster 5 with 4 documents is represented with purple color in Figure 3 corresponds to the distribution and concentrations of petroleum hydrocarbons 98 , the impact of polycyclic aromatic hydrocarbon on fish embryos 17 , and the environmental effects of the deepwater horizon oil spill 11 . ,

Co-Occurrence Analysis
Co-word analysis helps in identifying an intrinsic relationship when two or more keywords from a particular research area appear in the same article.The intensity of this relationship is represented by how many times these words have co-occurred in articles considered for the bibliometric analysis 122 .For conducting Co-word analysis, a bibliometric tool i.e., VOSviewer is used.Figure 4 represents keyword co-occurrence output from VOSviewer with those keywords that have a minimum occurrence of 50.Out of the total keywords i.e., 10641 only 77 keywords met the threshold.The analysis resulted in 3 main clusters.The largest cluster with 26 keywords (represented in red color in Figure 4) was populated with prominent keywords like environmental monitoring 32,87,107 , environmental impact 59,114 , risk assessment 97,102,31 , ecosystem restoration 93 and oil spill response 61,40,52 .This cluster highlighted the importance of quality assurance/quality control and different methods to ensure consistency and comparability of data collected from marine information systems for environmental monitoring 32,87,107 .Another highly emergent research area in the cluster was found to be health risk assessment caused due to a variety of factors arising from oil spills like seafood contamination 97 , cancer caused due to polycyclic aromatic hydrocarbons 102 and health risk caused by exposure to benzene 31 .Cluster 2 is highlighted in green color in Figure 4 and is anchored with keywords like bioremediation 7,95,14,90 biodegradation 7,43,39 , metabolism 25,110,36 and microbial community 47,112,94 .As highlighted in cluster 2 of the cocitation analysis shown in Figure 1 this cluster also highlights the use of bioremediation and biodegradation for reducing the impact of oil spills on the environment 7,43 .Another interesting theme highlighted in the cluster corresponds to changes in metabolic scope indicating changes in fishes' ability to face environmental contingencies 25,110,36 and microbial community dynamics that lead to oil degradation 47,112 .Cluster 3 is shown with blue color in Figure 4 and corresponds to marine toxicity and its impact on aquatic life.The cluster is manifested with keywords like polycyclic aromatic hydrocarbon 4,82,112 toxicity 49,68,83 and Gulf of Mexico 4,98 .It was worth noting that most of the studies related to polycyclic aromatic hydrocarbon exposure to aquatic life relate to deep water horizon blowouts in the Gulf of Mexico.

Bibliographic coupling
Based on the idea that works that share a large number of references are likely to have similar subject matter 117 , the bibliographic coupling is a method for science mapping.The analysis is most effective when applied to a narrow window of time and is focused on organizing publications into theme clusters based on shared references 130 .Bibliographic coupling (as opposed to co-citation analysis) helps bring attention to newer and more specialized publications by grouping them depending on their citing publications.That's why bibliographic coupling works well for business researchers who are interested in learning about the latest advancements across a wide range of topics.Since this is a current snapshot, the analysis can serve as an illustration of the current state of the field.Figure 3 represents bibliographic coupling output from VOSviewer with those documents that are published between 2020 to 2023 and with a minimum of 20 citations.Out of 300 total documents, only 15 met the threshold forming 5 clusters.Cluster 1: The key areas of research that appeared from this cluster were, the impact of integrated application of biochar, rhamnolipid (RL) biosurfactant, and nitrogen (N) on petroleum hydrocarbon remediation on soil microbial community 116 .Activated charcoal enrichment strategies for facilitating bioremediation of anoxic oilcontaminated sediments and soils 12 .Application of this cold-tolerant strain in the bioremediation of dieselcontaminated soil 2 , crude oil degradation bacteria 126 , and phytoremediation 65 .Cluster 2: The key areas of research in this cluster are volatile organic compounds 89 , Bacillus licheniformis 57 , Transformation of soil microbial community under oil pollution stress 48 and polyaromatic hydrocarbons and saturated hydrocarbons degradation method 41 .Cluster 3: Documents in this cluster relate to areas like environmental monitoring 27,67 changing environment on marginal coral reefs 104 and Polycyclic aromatic compounds in marine bird species 88 .Cluster 4: This cluster highlighted areas such as probabilistic risk assessment of oil spills 45 , polycarbonate and activated charcoal for emphatic oil-water separation 38 and impact of oil spills on marine mammals with polar cod responses 34 .

Intellectual Structure-Co-authorship Analysis
Co-authorship analysis helps in examining the areas of research collaborations among authors.Figure 6 represents the co-author network with authors having a minimum of 50 citations and 6 documents.The network resulted in 4 key clusters.Cluster I consisted of 4 authors, i.e., Hazen T.C., Greer C.W., Brakstad O.G., and Lee K where Lee K., is a liaising author between clusters 1,3, and 4. The key research area in this cluster was the biodegradation of oil spills at lower temperatures 37,94 .Cluster 2 consisted of 4 authors i.e., Li J., Li Y., Wang X., and Zhang H. where Zhang H. and Li Y were liaising authors.The common interest area of these authors was hydrophobic and oil sorbent based on jute fiber.Cluster 3 was populated by 3 authors i.e., Guo J., Li X., and Wang C. who collaborated on research in areas like remediation of crude oil-polluted soil by the bacterial rhizosphere community 126 , effects of diesel oil spill on microbenthic assemblages at the intertidal zone 129 , oil spill detection algorithm 128 and biodegradation using aboriginal bacterial consortium 123 .Cluster 4 consisted of only 2 authors i.e., Lui X. and Wang Y.The common research area of these two authors are environmental impact and recovery post-oil spills 114 and public attitudes toward funding oil pollution clean-up 64 .

Social Structure
Based on works that have been collaboratively published, the social structure analyses the connections (the degrees of scientific collaboration) between players operating at various levels (authors, institutions, and nations).This section tries to decipher the social structure amongst collaborating nations.Because there were only 37 singleauthored publications in the dataset, collaboration and teamwork (914 publications written in collaboration) were found to be crucial factors for writers exploring various aspects of Oil spills.6, Illustrates country publication analysis, where SCP is single-country publications (articles authored by writers from a single nation) and MCP is multi-country publications (articles authored by writers from several nations).When considering the multi-country publications ratio, Germany was found most open to global collaborations (MCP_Ratio=0.6)followed by Norway (MCP_Ratio=0.457),the United Kingdom (MCP_Ratio=0.444),Finland (MCP_Ratio=0.389),Brazil (MCP_Ratio=0.367),Spain (MCP_Ratio=0.318),France (MCP_Ratio=0.314),China (MCP_Ratio=0.284),Canada (MCP_Ratio=0.2),and USA (MCP_Ratio=0.168).The United States despite being the most productive nation was found to have the least global collaborations.

The Contemporary and Sustainable Oil Spill Clean-up Techniques
This section focuses on a bibliometric investigation to explore contemporary and sustainable oil spill clean-up techniques employed by researchers in their studies.As per the dataset (N=951), a number of methods could be used for oil spill clean-ups.These include mechanical containment and recovery, using chemical dispersants, insitu burning, sorbents, and bioremediation 116,64 .This study employed the procedure of content analysis on selected documents to identify environmentally sustainable and recent oil clean-up techniques.Content analysis is described as a process of analyzing and communicating in a methodical and quantitative manner with the aim of identifying the hidden dimensions of the given research area 55 .The most recent highly cited publications were reviewed thoroughly to identify contemporary and sustainable oil spill techniques.The result of the content analysis highlighted "Bioremediation" as one of the techniques of oil spill recovery.Bioremediation is a method for treating water polluted with petroleum hydrocarbons.The use of microorganisms that can break down the pollution to supplement the current system (bioaugmentation), stimulate natural biodegradation processes, and monitor and confirm those processes (natural attenuation) are all examples of bioremediation procedures.Compared to other methods of mitigating oil spills, bioremediation is one of the most environmentally friendly methods since it enables microorganisms to break down harmful hydrocarbons into simple chemicals that don't harm the environment 10 .Further, there are numerous techniques where the spills have been treated with enhanced bioremediation procedures.Some of the contemporary oil spill techniques discussed in the data set (N=951) were:

Nano-Remediation
One of the studies titled "Nano-enhanced Bioremediation for Oil Spills: A Review" authored by 84 discussed nanoenhanced bioremediation for cleaning oil spills which is the combination of bioremediation and nano-remediation where nanoparticles have primarily been used as magnetic sorbents and can also function as emulsifiers, increasing the bioavailability of the oil by providing microbes with a surface to attach to and encourage proliferation.

Bioaugmentation
Biological augmentation is an enhanced technique of using bacterial cultures required to speed up the rate of degradation of hydrocarbon pollutants.The most recent study titled "Bioaugmentation enhance the bioremediation of marine crude oil pollution: Microbial communities and metabolic pathways" authored by Gao et al., (2023)  discussed bioaugmentation, an effective technique that speeds up the process of bioremediation for oil spills by using highly efficient petroleum degrading bacterium.Another study authored by 13 also discussed the usage of native microorganisms having a better capacity for surviving in the natural environment while eliminating unforeseen ecological effects linked to the introduction of non-native species to boost the efficacy of bioremediation.

Phytoremediation
Phytoremediation is the process of using plants and other soil microbes to remove, disintegrate, stabilize, mineralize, or degrade the toxicity of the hydrocarbons from the contaminated area 75 .The author also concluded that phytoremediation along with the combination of Jatropha Curcas (JC) reduces hydrocarbon levels in the contaminated area.

Hydrophobic and Oil Sorbent Based on Jute Fiber
Natural fiber is less likely to cause pollution than other modified materials, has adequate buoyancy, is biodegradable by microorganisms, and is environmentally benign.The modified fiber has a water contact angle (CA) of 136.2° in comparison to the hydrophilic raw fiber, indicating that the substance possesses good , 01050 (2024) BIO Web of Conferences https://doi.org/10.1051/bioconf/2024860105086 RTBS-2023 hydrophobicity.After the jute fiber was modified, the capacity to adsorb water fell from 8.53 0.03 g/g to 0.92 0.02 g/g.The thermodynamic parameters prove that the adsorption of diesel onto modified jute is a spontaneous and favorable process 132 .It was found that the maximum adsorption capacity of the modified fiber is higher than most of the inorganic adsorbents.Although some adsorbents had better adsorption capacity than modified jute, they are expensive and difficult to biodegrade.So, on the basis of cost and biodegradability, modified jute fiber has better prospects 132 .

Hot Spots for Future Research-Thematic Maps
A thematic map helps understand the conceptual structure of a research area.It uses a network map of keywords occurrence to identify four themes i.e., motor theme, basic theme, niche theme, and emerging/declining themes 28 .Figure 6 shows the thematic map created with the help of a Biblioshiny tool with 500 words with a high occurrence and minimum cluster frequency of 5 per thousand keywords.As shown in the lower left quadrant of Figure 7 the key emerging/declining areas are the use of biochar, biosurfactant, and nitrogen for restoring affected areas due to oil spills pollutants 116,105 biostimulation for biodegradation of contaminated soil 101 , volatile organic compound emissions 89,12146 , remote sensing of marine oil spills 105,79 and oil-saltwater separation with different permeable membranes 118,72,33.Whereas the upper lefthand quadrant shows themes that are of high density but low centrality and represent niche themes.The key niche themes highlighted in this quadrant are the impact of chemical dispersants on marine life 21,5 nanoparticle-based dispersants for marine oil spill 96 , the effect of polycyclic aromatic hydrocarbon on marine life like cardiovascular function and fish development 39 , Liver antioxidant and plasma immune responses in juvenile golden grey mullet to polycyclic aromatic hydrocarbons and human health risk assessment due to polycyclic aromatic hydrocarbon 105 .

Hot Spots for Future Research-Content Analysis
To supplement the results of the thematic map, a content analysis of recent and highly cited publications published between 2020 to 2023 was performed.The four most cited publications from each year were reviewed with a special focus on the 'Scope for future research' section to decipher the future hot spots in the Oil Spills research domain.Since the year 2023 had only one publication with one citation, rest three publications from the year 2023 were selected based on the impact factor of the journals.The details are mentioned as follows in

Conclusion and discussion
This bibliometric investigation was an attempt to conduct performance analysis and science mapping of research constituents in oil spill literature.This investigation also tried to unearth contemporary yet sustainable oil cleanup techniques using content analysis.At last, the bibliometric investigation tried to conclude hot spots for future research using a research triangulation (bibliometric thematic maps and content analysis).This section concludes and builds a discussion on the findings of this study.
Increased research vigor in specific years causing peaks in the number of publications could be attributed to oil spills that shook the world for environmental detrimental effects on flora and fauna including local communities.Working towards unearthing the most cited publication, "Oil biodegradation and bioremediation: A tale of the two worst spills in U.S. history", authored by Atlas and Hazen (2011) was found to be the most influential publication in the dataset.The most probable reason for being the most cited publication apart from it being an old publication could be the future forward approach in this publication that suggested employing the biological pathways inside microbes or plants engaged in the bioremediation of oil spills as an effective method to treat oil spills.
Li Y (NP=13, AF=3.08) and Wang C, (NP=15, AF=2.70) were found to be the two of the most productive authors (Table 3a).The reason behind authors of Chinese origin taking leadership positions as most productive authors could be attributed to the fact that China has been a victim of numerous blowouts and pipeline failures and that some of the biggest oil spill incidents in the past few years include the Xingang Port spill in China thereby creating an obvious research motivation.The same reasons could be extended to the results of most cited authors where Chinese authors (60%) made up the list of most cited authors (Table 3b).Hazen TC with 847 citations was found to be the most impactful author.The reason behind his work being one of the most cited works could be his contribution to employing the biological pathways inside microbes or plants engaged in the bioremediation of oil spills as an effective method to treat oil spills; an area that gained a lot of traction since 2011 onward.With 118 publications in the dataset, the "Marine Pollution Bulletin" was the most productive source while with 3945 total citations, "Environmental Science and Technology" was found to be the most impactful source in the dataset.Because both journals strive to disseminate high-quality research on marine pollution and its impacts and help promote the creation of remedies to this pressing ecological issue, they serve as a natural fit to the emerging field of 'Oil spills'.
With 273 publications USA and with 95 publications China, were the two most productive nations to publish on oil spills.Not only that the USA is a major producer and consumer of oil, but it has also witnessed some of the most disastrous and publicized oil spills in history.Therefore, the nation has a longstanding stake in investigating and creating oil spill prevention, response, and mitigation.Moreover, through bodies such as the "National Oceanic and Atmospheric Administration (NOAA)", the "Environmental Protection Agency (EPA)", and the "National Science Foundation (NSF)", the US government contributes significant funding and support to oil spillrelated research.
Highly Co-cited publications represent key concepts that can be used to map the relationship between these key concepts.Co-citation analysis in this investigation, therefore, enabled identifying foundational themes.The explosion of the Deepwater Horizon oil drilling rig in the Gulf of Mexico on April 20, 2010, resulted in the release of an estimated 5.3 × 108 kg of oil and 1.7 × 108 kg of gas from the Macondo well (MW), (1-3) making it the largest marine spill in US history.This cluster highlights the Deepwater Horizon oil spill due to its highly publicized environmental, economic, and social impacts.
The results of the co-citation analysis were supplemented by keyword occurrence analysis.The largest cluster in Figure 4 is represented in red and consists of 26 keywords.Prominent keywords in this cluster include environmental monitoring, environmental impact, risk assessment, ecosystem restoration, and oil spill response.The results are in tandem with an increased worldwide focus on seeking not only tracking and prevention of oil spills but also post-oil spill treatment techniques in the wake of increasing oil spill cases.
Bibliographic coupling groups newer and specialized publications based on their citing publications, highlighting the latest advancements across a wide range of topics.This method works well for business researchers and provides a current snapshot of the field.Biochar enrichment strategies for facilitating bioremediation, coldtolerant strains for bioremediation of soil, crude oil degradation bacteria, and phytoremediation were some of the topics brought to light by the main cluster with the impact of integrated application of biochar, rhamnolipid biosurfactant, and nitrogen on remediation of petroleum hydrocarbons.
Hazen T.C., Greer C.W., Brakstad O.G., and Lee K were found to have maximum documents co-authored together.These authors were found to have an overlap in their areas of research interest.In co-authored documents , 01050 (2024) BIO Web of Conferences https://doi.org/10.1051/bioconf/2024860105086 RTBS-2023 and as well as in independent documents, the authors worked on the biodegradation of oil spills in cold temperatures.
With an MCP_Ratio of 0.66, Germany was the only country to have more multi-country collaborations than single-country collaborations, making Germany the most open for international collaborations in oil spill research.This could be due to the fact that both nations have a strong commitment to accomplishing SDG Goals (Life Below Water, Climate Action, and Life on Land) and are situated in the North Sea region, which has a long history of oil and gas extraction and transport.
To explore the contemporary yet sustainable methods for oil clean-up, a content analysis of recent publications working on oil clean-up and remediation was conducted.Bioremediation along with other related techniques like Nano-Remediation 84 , Bioaugmentation 133 , and Phytoremediation 75 emerged as the most prominent sustainable oil clean-up technique having the most potential to be employed on a large scale.Yet another emergent sustainable oil clean-up technique was hydrophobic and oil sorbents based on jute fibers.This is because natural fiber like jute with appropriate adjustments is less likely to cause pollution than other modified materials, has adequate buoyancy, is biodegradable by microorganisms, and is environmentally benign.
One major contribution of this bibliometric and content analysis discourse was to unearth hot spots for future research areas.Establishing effective oversight and reaction strategies, assessing the efficacy of various oil disaster clean-up techniques, improving global VOC emissions inventories, studying the distribution and health effects of VOC exposure, exploring innovative mitigation methods, and exploring organic and bio-based remediation procedures were some of the hot spot areas of future research.A few publications advise evaluating remote sensing for oil spill identification and monitoring and assessing the combined effects of many stressors on maritime ecosystems.Other research future research areas include the long-term effects of heavy metal pollution, in-situ burning strategies, salt marsh and coastal ecosystem restoration, and fuel pollution in Antarctica.

Fig. 1
Fig. 1 Preferred reporting items for systematic review and methodology

Figure 2
Figure 2 demonstrates the publication and citation evolution from 1973 to 2023.A publication titled "The impact of impact studies" 44 marked the beginning of the publication trajectory highlighting the environmental impacts of oil spills.The publication focused on how the Santa Barbara oil spill of January 1969 led to the emergence of the National Environmental Protection law from just an act in the United States.With somewhat slow growth in the number of publications till 2005, the publications covering various aspects of oil spills; from 'damage' to 'damage control' have witnessed a sharp increase from 2006 onwards.

Fig. 2
Fig. 2 Publication and citation evolution from 1973 to 2023

Table . 1
Most Influential Publications

Table . 2
Research Questions and Outcomes of Top Ten Most Influential Publications

Table 3b : Most Impactful Authors
Table3ashows the most productive authors.As many authors contributed an equal number of publications (e.g., Engel L.S and Li Y; NP=13) in the field, this necessitated ranking the authors based on the article fractionalized score (the fractionalized frequency distribution of articles) rather than just the total number of publications.As evident in Table3a, Li Y (NP=13, AF=3.08) was found to be the most productive author in the dataset.Use of a novel hydrophobic magnetic biochar to treat oil spills (2018), modulating the spatial discretization used in oil spill simulations along coastlines (2007) and distribution scheme, risk evaluation, and reasons for petroleum hydrocarbons in the Yellow River estuary and nearby coastal area in China (2017) were some of the influential works contributed by Li Y.
Wang C, (NP=15, AF=2.70) was found to be the second most productive author.Sedimentary petroleum, aliphatic, and polycyclic aromatic hydrocarbon concentrations and sourcing in Bohai Bay and the nearby river (2015), weathering and fingerprinting of crude oils following China's Dalian oil spill (2013), The ability of a recently identified strain to remove polycyclic aromatic hydrocarbons (PAHs) from oilfield generated water (2017) and use of indigenous bacterial consortia for marine oil spill clean-up in China's Penglai 19-3 oil spill (2018) were major influential areas of contribution by Wang C.

Table . 4a
Top Ten Most Productive Journals

Table 4b : Top Ten Most Impactful Journals
Source: SCOPUS and Author's Compilations; Note: TC= Total Citations, TP= Total Publications, PY_start= Publication Year Start

Table . 6 Country Collaboration Analysis
Source: SCOPUS database and Author's Compilation Note: SCP-Single Country Collaboration, MCP-Multi-Country Collaboration, MCP_Ratio-Multi-Country Collaboration Ratio

Table 7 :
Hot Spots for Future Research Source: SCOPUS Database and Authors; Compilation; Note: TC-Total Citations North Slope in Alaska by BP Alaska in March 2006.Similarly, the Montara oil spill (August 21, 2008, Australia), the Hebei Spirit oil spill (December 7, 200, South Korea), and the Bonga oil spill (December 20, 2008, Nigeria) caused a publication spike in 2008.The Agia Zoni II oil spill (September 10, 2017, Saronic Gulf, Greece), the Keystone Pipeline leak (November 16, 2017, South Dakota), and the Sea Rose FPSO spill (November 16, 2017, Canada) caused a sharp peak in 2017.The last peak in the year 2021 could be attributed to oil spills such as the MV X-Press Pearl disaster (May 20, 2021, Shri Lanka), the Israel-Lebanon oil spill (February 2021, Eastern Mediterranean Sea) and the Sunken Vessel offshore California spill (October 2021, Southern California).
The first peak(2006)was the result of instances where nearly 2.1 million liters (approximately 555,000 gallons) of bunker fuel were spilled when the oil tanker M/T Solar 1, chartered by Petron Corporation, collapsed off the coast of Guimaras, in the Philippines, on August 11, 2006.This oil leak, till today, is remembered as the most catastrophic in Philippine history.Further, roughly 5,054 barrels of crude oil were accidentally released on the Zulkharnain, A., Zakaria, N. N., Roslee, A. F. A., Abdul Khalil, K., Napis, S., Convey, P., Gomez-Fuentes, C., & Ahmad, S. A. (2020, August 27).Response Surface Methodology Optimization and Kinetics of Diesel Degradation by a Cold-Adapted Antarctic Bacterium, Arthrobacter sp.Strain AQ5-