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Complex co‐substrate addition increases initial petroleum degradation rates during land treatment by altering bacterial community physiology
Author(s) -
Kaplan Christopher W.,
Clement Brian G.,
Hamrick Alice,
Pease Robert W.,
Flint Carl,
Cano Raul J.,
Kitts Christopher L.
Publication year - 2003
Publication title -
remediation journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.762
H-Index - 27
eISSN - 1520-6831
pISSN - 1051-5658
DOI - 10.1002/rem.10084
Subject(s) - degradation (telecommunications) , nutrient , substrate (aquarium) , population , environmental chemistry , chemistry , bacteria , biology , ecology , organic chemistry , medicine , telecommunications , genetics , computer science , environmental health
A pilot‐scale land treatment unit (LTU) was constructed at the former Guadalupe oil productionfield with the purpose of investigating the effect of co‐substrate addition on the bacterial community andthe resulting rate and extent of total petroleum hydrocarbon (TPH) degradation. The TPH was a weatheredmid‐cut distillate (C10‐C32) excavated from the subsurface and stockpiled beforetreatment. A control cell (Cell 1) in the LTU was amended with nitrogen and phosphorus while theexperimental cell (Cell 2) was amended with additional complex co‐substrate—corn steepliquor. During the pilot LTU operation, measurements were taken of TPH, nutrients, moisture, aerobic heterotrophicbacteria (AHB), and diesel oxidizing bacteria (DOB). The bacterial community was also assayedusing community‐level physiology profiles (CLPP) and 16S rDNA terminal restriction fragment(TRF) analysis. TPH degradation in both cells was characterized by a rapid phase of degradation thatlasted for the first three weeks, followed by a slower degradation phase that continued through the remainder ofthe project. The initial rate of TPH‐degradation in Cell 1 (−0.021 day −1 )was slower than in Cell 2 (−0.035 day −1 ). During the slower phase, degradationrates in both cells were similar (−0.0026 and −0.0024 respectively). AHB and DOB counts weresimilar in both cells during the fast degradation phase. A second addition of co‐substrate to Cell 2 at thebeginning of the slow degradation phase resulted in an increased AHB population that lasted for the remainder ofthe project but did not affect TPH degradation rates. CLPP data showed that co‐substrate addition alteredthe functional capacity of the bacterial community during both phases of the project. However, TRF data indicatedthat the phylogenetic composition of the community was not different in the two cells during the fast degradationphase. The bacterial phylogenetic structure in Cell 2 differed from Cell 1 after the second application ofco‐substrate, during the slow degradation phase. Thus, co‐substrate addition appeared to enhance thefunctional capacity of the bacterial community during the fast degradation phase when the majority of TPH wasbioavailable, resulting in increased degradation rates, but did not affect rates during the slow degradation phasewhen the remaining TPH may not have been bioavailable. These data show that co‐substrate addition mightprove most useful for applications such as land farming where TPH is regularly applied to the same soil andinitial degradation rates are more important to the project goals. © 2003 Wiley Periodicals, Inc.