Analysis of polycyclic aromatic hydrocarbons in the Gulf of Mexico 7 years after the Deepwater Horizon oil spill
Kate Fitzsimmons
Scientific article: https://www.nature.com/articles/s41598-020-62944-6
News article: https://www.cnn.com/2020/04/20/world/deepwater-horizon-spill-anniversary-fish-study-scn/index.html
The article I will be reviewing today is titled “10 years after the Deepwater Horizon oil spill, oil pollution found in thousands of fish, study says.” The article was published by CNN on April 20, 2020 written by Ashley Strickland, a prominent science and space journalist. This article focuses primarily on a paper published in Nature, “A First Comprehensive Baseline of Hydrocarbon Pollution in Gulf of Mexico Fishes,” on April 15, 2020. This paper discusses the biliary accumulation of polycyclic aromatic hydrocarbons (PAHs) in fish in the Gulf of Mexico for the 7 years (2011-2018) after the Deepwater Horizon (DWH). Deepwater Horizon was the largest oil spill in history 4.9 million barrels of oil spilled into the Northern part of the Gulf of Mexico (GoM) in 2010, about 40 miles off the coast of Louisiana.
The study conducted comprehensive Gulf-wide fish surveys to assess post-DWH PAH concentrations in fish, aiming to understand temporal and spatial exposure differences among species and regions and monitor long term trends over the course of the study. This was done by determining the Biliary PAH metabolite concentrations in 2,503 fish across various habitats, water temperatures and depths, and distances from oil spills and leaks.
Figure 1 Spatial concentration maps for mean (a) biliary naphthalene and (b) benzo[a]pyrene equivalents:
Figure 1 displays findings of the spatial concentrations of two biliary PAHs, naphthalene and benzo[a]pyrene. Naphthalene comes from petrogenic sources such as oil platforms, refineries, vehicle exhaust, evaporated gasoline, diesel fuel, and boat discharge. These concentrations are expected to be high near major population centers and areas with high density of oil and gas infrastructure. Alternatively, Benzo[a]pyrene is formed by the incomplete, short duration combustion of various fossil fuels and organic matter at high temperatures (pyrogenic sources). Concentrations are expected to be high close to anthropogenic sources associated with the petroleum industry and run off. The study emphasizes that the amount of PAHs continues to fluctuate over time as spills and natural seeps continue to occur after the Deepwater Horizon.
Overall, the study finds that fish in the north central region of the GoM had significantly higher PAH concentrations compared to other regions. Moreover, the temporal analysis revealed a 108% increase in oil exposure from 2011 to 2017 in the north central region; There was a 24% decline in exposure for the first 3 years followed by a 173% increase by the end of the study. Additionally, contrary to expectations, there was no notable correlation between exposure to PAHs and factors such as water temperature, depth, trophic level, habitat preference, or biometric measures.
This study provides insight into the baseline concentrations of PAH across species in the Gulf of Mexico, which will be vital to future research and understanding of the impacts of Deepwater Horizon. Additionally, I think the more interesting findings of this study are the high discrepancy concentrations of PAHs between male and female fishes across species and the high concentrations of PAHs in Yellowfin Tuna despite less exposure to contaminants than other species. As the paper states, this is likely due to variation in metabolism and processing of these toxins.
As for the CNN article, I think it provides a decent summary of the scientific paper. It does a good job at introducing the background information surrounding the study, such as the funding and the timeline in relation to Deepwater Horizon. I was pleasantly surprised when the author discussed additional sources of oil and gas pollution in the Gulf other than Deepwater Horizon. I expected the article to exclude other oil sources as to potentially overrepresent the impact of the DWH, but Strickland briefly discussed other sources such as coastal runoff, boats, planes and natural seeps. Additionally, the article features quotes from the primary author of the paper. These quotes highlight notable findings, particularly the Yellowfin Tuna, and provide clear scientific explanation by the primary researcher, which makes the article feel more legitimate. Additionally, the article references other scientific articles that broaden the scope of the findings and provide useful context outside of the primary paper.
However, the article is not without its faults. It does not include any information about how PAHs really impact fish health.The scientific paper discusses how fish have well developed metabolic systems that can convert PAHs into water soluble compounds. It is only with long term exposure that these PAHs can start to bind to proteins and DNA causing mutations and other adverse reactions. The article also fails to discuss the other areas of high PAHs concentrations outside of the Deepwater Horizon spill area. I think it would have been useful to discuss more about the findings seen in figure 1. The concentration of PAHs outside of DWH might be unexpectedly high to the reader because those areas did not have a large single incident of contamination. Additionally, the article also does not elaborate on how comprehensive the study actually was and all the factors and conditions that the study accounted for. It does not discuss methodologies or the vast area that that study was conducted in. Finally, the title of the article says that the study was conducted 10 years after the Deepwater Horizon which is misleading because the study was conducted across 7 years after the spill; the findings were only published 10 years after DWH.
I do think, however, many of the issues were minor and do not detract from the more important findings of the study. Overall, I think the CNN article does a good job and I would rate it a 7.5/10.
Hi Kate, I absolutely agree with your point that the CNN article seems to "pull back" on the science when it comes to methodology and elaboration, though I also think this is largely necessary as a lot of readers won't follow a rabbit hole that seems different than the title. Speaking of, I also agree with your point about the time discrepancy between DWH and the data acquisition vs publishing, it seems a little misinformed. I also would've liked to have seen more information about these other areas, the article does a good job of acknowledging other oil and similar pollutants and I feel like this would've been a great place to segue into how this type of pollution impacts the entire gulf, not just the DWH area. Unfortunately I think this article had to chop a lot of the nitty gritty in favor of commenting the core idea, but think that this chopping could have been a little more careful, instead of leaving some fairly large questions for the general reader (who might not comprehend heavy scientific language).
ReplyDeleteI would agree with your point about the authors intention of the CNN article. I think the intention of this and other science review articles is to chop the nitty gritty in favor of the core idea. This is a difficult balance that these science journalist need to strike reviewing a paper such as this. However, I feel like it is often more enriching to the reader to extent the scope of the paper into areas that are more familiar to them. Additionally, I often find, when I'm reading an article at least, I do like a more little detailed explanation of the science put in plain terms. It often helps me to understand the article and cut thought the jargon and I feel like this is the purpose of the CNN article.
DeleteI also agree that the news article didn't do a great job of summarizing the scientific data, I was surprised that they didn't explain more about the methods used and exactly how the data were collected. I also wondered if the title of the CNN article was a bit misleading. The research paper explained that there have been over 300 oil spills in the GoM as well as natural oil seeps and runoff. Although the deepwater oil spill in 2010 was the largest, there's no way to say definitively that the PAHs were a result of that specific spill; especially because there hadn't been a clear baseline before this study. Lastly, I think that the study could have given more information about the PAH levels in the GoM compared to other parts of the ocean because they mentioned that petroleum is not the only source of PAHs. Pyrogenic sources also create these hydrocarbons so I wonder exactly how much higher they are in the GoM since there is so much pollution in other parts of the ocean.
ReplyDeleteHi Esme, these are great points. I would agree that the scientific article doesn't do a great job at broadening the scope of the findings beyond the GoM. The results of the study seem inconsequential without being put into terms of places outside of the GoM where there are a high amount of oil and gas infrastructure. The only place I believe in the paper they talk about other polluted waterways was with one line "The range of PAH exposures measured throughout the GoM is comparable to other polluted coastal waterways and areas immediately following oil spills." The paper did not include any citation for this statement either. This would have been a grievance if I were to have been rating the scientific article.
DeleteI agree that the CNN article did not do an excellent job summarizing the scientific paper. One area this was apparent was the news article's presentation of the reason behind high concentrations of PAH in yellowfin tuna. Strickland uses a quote from lead author Pulster explaining the team's initial confusion regarding high PAH concentrations in the fast-moving yellowfin tuna, but fails to include the group's hypothesis provided within the scientific paper. The Nature paper proposes, the assumption that PAH's do not bioaccumulate in fish is incorrect in instances of "chronic, long-term exposure" and that fish do not posses the capacity to repair DNA damage sustained in such an environment. The inclusion of this latter portion would have provided the reader a more accurate representation of the research group's position.
ReplyDeleteYou're right about the CNN article missing a key point from the scientific paper. The article mentioned the confusion about high PAH concentrations in yellowfin tuna but left out the team's hypothesis. The paper suggests that fish can accumulate PAHs over time, impacting their ability to repair DNA damage. This crucial detail was omitted in the news coverage, which could have given a clearer picture of the researchers' findings.
DeleteIn considering the broader implications of this study, it prompts us to rethink our approach to environmental monitoring and resource management. The findings underscore the persistent and far-reaching consequences of major oil spills, urging us to adopt more proactive strategies for prevention and mitigation. Instead of merely responding to catastrophic events, a shift towards continuous monitoring and real-time assessment could provide a more dynamic understanding of ecological health. Integrating cutting-edge technologies, such as remote sensing and advanced data analytics, could enable us to detect subtle changes in pollutant levels and species health, offering a more agile and informed response to potential environmental threats. This study serves as a reminder that innovation in both scientific research and environmental policy is crucial for safeguarding our oceans and aquatic ecosystems in the face of ongoing challenges.
ReplyDeleteI agree with your point about understand the science is important to underscoring the need for innovation in research and policies to protect our oceans. This is why I think it is important to elaborate on the findings beyond the scope of just the GoM near the USA. Additionally, it is important to correctly translate the science so readers know what to discuss with their politicians.
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