Identifier

etd-07012013-113825

Degree

Master of Science (MS)

Department

Environmental Sciences

Document Type

Thesis

Abstract

In 2010, the Deepwater Horizon (DWH) oil spill, released 4.9 million barrels of oil into the Gulf of Mexico, creating the largest marine oil spill in the history of the U.S. petroleum industry. Trace metals, including those from crude oil, were dispersed in the water column and bound to suspended particulates. As obligate filter-feeding omnivores and a predominate fishery in the Gulf of Mexico, Gulf menhaden (Brevoortia patronus) are susceptible to trace metal accumulation. Samples of menhaden were collected at two locations in coastal Louisiana, Grand Isle (GI) and Vermillion Bay (VB), with VB serving as the non-impacted DWH oil spill site and GI as the impacted DWH oil spill site. The analysis of trace metals was performed using inductively coupled plasma-optic emission spectroscopy (ICP-OES) methods. Eleven metals (As, Ba, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn, V) were chosen and observed by four variables: place (VB or GI), size (small or large), month (July, August or September), and year (2011 or 2012) and the interactions between the variables. Metal concentrations in the current study followed the sequence: Fe > Zn > Ba > As > V > Cr > Cu > Ni > Pb > Co > Cd. Results showed that in 2011, VB had statistically higher concentrations than GI for 9 of the 11 metals. Elevated discharge rates during the Mississippi River Flood of 2011 produced a dilution effect, decreasing the concentration of trace metals in the water column at GI. Size was also significant, with small fish having statistically higher concentrations for 8 of the 11 metals. In fish, younger/smaller fish have higher metabolic activities than older/larger fish, which leads to a higher metal accumulation in smaller fish. Arsenic was the only metal that had higher concentrations in 2011 and in large fish. Differences in arsenic trends may be attributed to the DWH oil spill, which may have caused reduced adsorption of arsenic by the mineral goethite and increased concentrations of arsenic in the water. Iron and zinc in the current study exceeded the FAO/WHO maximum permissible limit.

Date

2013

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Gambrell, Robert P

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