Browsing by Subject "oil spills"

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Impacts of oil spills: Ecological, human health and economic
(2011-05-06) Lee, Hannah; Katz, Lynn E.; Min, Dong-Ha
The 1979 Ixtoc I and 2010 Deepwater Horizon are the two largest accidental oil spills that have occurred in history, and both have been near United States waters. After an oil spill occurs, ecology, human health and economy are major concerns. Specifically, this thesis discusses the impacts of oil spills on microbes, marine organisms, human health and revenue. The major focus of this research was on the oil spills near the Gulf of Mexico. Although there have been numerous oil spills in history, these two spills were chosen because they were the largest in volume and time. While spills from oil tankers are more common, both of these oil spills were caused by broken wellheads. Most of the data and analysis conducted in this research utilized information from Ixtoc I and Deepwater Horizon. However, Ixtoc I was not highly publicized and there was not sufficient data on the long term impacts of Ixtoc I in the Gulf of Mexico. Therefore, data was extracted from the 1989 Exxon Valdez oil spill. The research methodology consisted of a review of published journal articles that provided information to address the question “What are the long term and short term effects of oil spills on ecology, human health and the economy?” Short term impacts included the creation of hypoxia closer to the surface of the ocean causing marine life to die or flee, closure of waters to fishing resulting in economic impacts on surrounding communities, and various human health symptoms such as respiratory, ocular and dermal. Many animal species at risk of being endangered before the spill were at risk of long term consequences due to an inability to return to pre-spill population sizes.
Interactions between Zooplankton and Crude Oil: Toxic Effects and Bioaccumulation of Polycyclic Aromatic Hydrocarbons
(PLOS, 2013-06-28) Almeda, Rodrigo; Wambaugh, Zoe; Wang, Zucheng; Hyatt, Cammie; Liu, Zhanfei; Buskey, Edward J.
We conducted ship-, shore- and laboratory-based crude oil exposure experiments to investigate (1) the effects of crude oil (Louisiana light sweet oil) on survival and bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in mesozooplankton communities, (2) the lethal effects of dispersant (Corexit 9500A) and dispersant-treated oil on mesozooplankton, (3) the influence of UVB radiation/sunlight exposure on the toxicity of dispersed crude oil to mesozooplankton, and (4) the role of marine protozoans on the sublethal effects of crude oil and in the bioaccumulation of PAHs in the copepod Acartia tonsa. Mortality of mesozooplankton increased with increasing oil concentration following a sigmoid model with a median lethal concentration of 32.4 ml L21 in 16 h. At the ratio of dispersant to oil commonly used in the treatment of oil spills (i.e. 1:20), dispersant (0.25 ml L21 ) and dispersant- treated oil were 2.3 and 3.4 times more toxic, respectively, than crude oil alone (5 ml L21 ) to mesozooplankton. UVB radiation increased the lethal effects of dispersed crude oil in mesozooplankton communities by 35%. We observed selective bioaccumulation of five PAHs, fluoranthene, phenanthrene, pyrene, chrysene and benzo[b]fluoranthene in both mesozooplankton communities and in the copepod A. tonsa. The presence of the protozoan Oxyrrhis marina reduced sublethal effects of oil on A. tonsa and was related to lower accumulations of PAHs in tissues and fecal pellets, suggesting that protozoa may be important in mitigating the harmful effects of crude oil exposure in copepods and the transfer of PAHs to higher trophic levels. Overall, our results indicate that the negative impact of oil spills on mesozooplankton may be increased by the use of chemical dispersant and UV radiation, but attenuated by crude oil-microbial food webs interactions, and that both mesozooplankton and protozoans may play an important role in fate of PAHs in marine environments.