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Water Air Soil Pollut (2012) 223:31453154 DOI 10.1007/s11270-012-1097-5
Seasonal Monitoring of Hydrocarbon Degraders in Alabama Marine Ecosystems Followingthe Deepwater Horizon Oil Spill
Agota Horel & Behzad Mortazavi &
Patricia A. Sobecky
Received: 10 October 2011 /Accepted: 31 January 2012 /Published online: 29 February 2012 # Springer Science+Business Media B.V. 2012
Abstract Following the Deepwater Horizon explosion and crude oil contamination of a marsh ecosystem in AL in June 2010, hydrocarbon-degrader microbial abundances of aerobic alkane, total hydrocarbon, and polycyclic aromatic hydrocarbon (PAH) degraders were enumerated seasonally. Surface sediment samples were collected in October and December of 2010 and in April and July of 2011 along 4070-m transects from the high tide to the intertidal zone including Spar-tina alterniflora-vegetated marsh, seagrass (Ruppia maritima)-dominated sediments, and nonvegetated sediments. Alkane and total hydrocarbon degraders in the sediment were detected, while PAH degraders were below detection limit at all locations examined during the sampling periods. The highest counts for microbial alkane degraders were observed at the high tide line in April and averaged to 8.65105 of cells/g dry weight (dw) sediment. The abundance of alkane degraders during other months ranged from 9.49103 to 3.87104,
while for total hydrocarbon degraders, it ranged between 5.62103 and 1.14105 of cells/g dw sediment. Pore water nutrient concentrations (NH4+, NO3, NO2, and PO43) showed seasonal changes with minimum values observed in December and April and maximum values in October and July. Concentrations of total petroleum hydrocarbons in sediments averaged 100.452.4 and 141.957.5 mg/kg in January and July, 2011, respectively. The presence of aerobic microbial communities during all seasons in these nearshore ecosystems suggests that an active and resident microbial community is capable of mineralizing a fraction of petroleum hydrocarbons.
Keywords Deepwater Horizon . Crude oil . Hydrocarbon degraders . Macondo well . Biodegradation . Salt marsh
1 Introduction
On April 21, 2010, the Deepwater Horizon oil rig explosion caused the release of approximately 4.4 106 barrels (7.0105 m3, 20%) of crude oil into the Gulf of Mexico during an 84-day period (Crone and Tolstoy 2010). A large fraction of the released oil underwent rapid biodegradation at depth in the deep sea (Hazen et al. 2010; Azwell et al. 2011), but some of the oil released into the water column reached the Northern Gulf of...