Simulation of aerobic and anaerobic biodegradation processes at a crude oil spill site


A two’dimensional, multispecies reactive solute transport model with sequential aerobic and anaerobic degradation processes was developed and tested. The model was used to study the field’scale solute transport and degradation processes at the Bemidji, Minnesota, crude oil spill site. The simulations included the biodegradation of volatile and nonvolatile fractions of dissolved organic carbon by aerobic processes, manganese and iron reduction, and methanogenesis. Model parameter estimates were constrained by published Monod kinetic parameters, theoretical yield estimates, and field biomass measurements. Despite the considerable uncertainty in the model parameter estimates, results of simulations reproduced the general features of the observed groundwater plume and the measured bacterial concentrations. In the simulation, 46% of the total dissolved organic carbon (TDOC) introduced into the aquifer was degraded. Aerobic degradation accounted for 40% of the TDOC degraded. Anaerobic processes accounted for the remaining 60% of degradation of TDOC: 5% by Mn reduction, 19% by Fe reduction, and 36% by methanogenesis. Thus anaerobic processes account for more than half of the removal of DOC at this site.


I chose this article because I don’t think I have read an article yet that solely compared two different types of microorganisms performing the same process. The differences between aerobic and anaerobic microorganisms are cool in general, but learning about how they each perform the same very specific task would be intriguing.   Although this is an older paper, I wanted to know what kind of simulations and models they made and used back then, and what future models or simulations could be created from then, now in the present day.



Eassaid, H. I., Bekins, B. A., Godsey, E. M., Warren, E., Baedecker, M. J., & Cozzarelli, I. M. (1995). Simulation of aerobic and anaerobic biodegradation processes at a crude oil spill site.  Water Resources Research, 31,  3309-3327.



Predictable bacterial composition and hydrocarbon degradation in Arctic soils following diesel and nutrient disturbance


Terrence H. Bell, Yergeau, E., Maynard, C., Juck, D., Whyte, L. G., & Greer, C. W. (2013). Predictable bacterial composition and hydrocarbon degradation in Arctic soils following diesel and nutrient disturbance.  The ISME Journal 7, 1200-1210.


Increased exploration and exploitation of resources in the Arctic is leading to a higher risk of petroleum contamination. A number of Arctic microorganisms can use petroleum for growth-supporting carbon and energy, but traditional approaches for stimulating these microorganisms (for example, nutrient addition) have varied in effectiveness between sites. Consistent environmental controls on microbial community response to disturbance from petroleum contaminants and nutrient amendments across Arctic soils have not been identified, nor is it known whether specific taxa are universally associated with efficient bioremediation. In this study, we contaminated 18 Arctic soils with diesel and treated subsamples of each with monoammonium phosphate (MAP), which has successfully stimulated degradation in some contaminated Arctic soils. Bacterial community composition of uncontaminated, diesel-contaminated and diesel+MAP soils was assessed through multiplexed 16S (ribosomal RNA) rRNA gene sequencing on an Ion Torrent Personal Genome Machine, while hydrocarbon degradation was measured by gas chromatography analysis. Diversity of 16S rRNA gene sequences was reduced by diesel, and more so by the combination of diesel and MAP. Actinobacteriadominated uncontaminated soils with <10% organic matter, while Proteobacteria dominated higher-organic matter soils, and this pattern was exaggerated following disturbance. Degradation with and without MAP was predictable by initial bacterial diversity and the abundance of specific assemblages of Betaproteobacteria, respectively. High Betaproteobacteria abundance was positively correlated with high diesel degradation in MAP-treated soils, suggesting this may be an important group to stimulate. The predictability with which bacterial communities respond to these disturbances suggests that costly and time-consuming contaminated site assessments may not be necessary in the future.



I chose this article because it investigates contamination in the Arctic, which would be interesting to  learn more about. This exploration deals with petroleum contamination, and microorganisms rely heavily on petroleum for growth-supporting carbon and energy.

Hand-Phone Microbiome Connection – Individual Thinglink Communities Project Post   General Audience Most people on planet Earth own a mobile cell phone. In fact, more people worldwide own mobile phones than have access to working toilets. But did you know that  we share more than just an emotional connection with our phones? That they carry our personal microbiome? The human microbiome is defined …

The effect of abrupt climatic warming on biogeochemical cycling and N2O emissions in a terrestrial ecosystem


Citation: Pfeiffer, Mirjam, J. van Leeuwen, W. O. van der Knap, and J. O. Kaplan. The effect of abrupt climatic warming on biogeochemical cycling and N2O emissions in a terrestrial ecosystem. 2012. Early Rapid Warning. 391: 74-83.

Abstract:  The large, rapid increase in atmospheric N2O concentrations that occurred concurrent with the abrupt warming at the end of the Last Glacial period might have been the result of a reorganization in global biogeochemical cycles. To explore the sensitivity of nitrogen cycling in terrestrial ecosystems to abrupt warming, we combined a scenario of climate and vegetation composition change based on multiproxy data for the Oldest Dryas—Bølling abrupt warming event at Gerzensee, Switzerland, with a biogeochemical model that simulates terrestrial N uptake and release, including N2O emissions. As for many central European sites, the pollen record at the Gerzensee is remarkable for the abundant presence of the symbiotic nitrogen fixer Hippophaë rhamnoides (L.) during the abrupt warming that also marks the beginning of primary succession on immature glacial soils. Here we show that without additional nitrogen fixation, climate change results in a significant increase of N2O emissions of approximately factor 3.4 (from 6.4 ±1.9 to 21.6 ±5.9mgN2O—Nm−2yr−1). Each additional 1000mgm−2yr−1 of nitrogen added to the ecosystem through N-fixation results in additional N2O emissions of 1.6mgN2O—Nm−2yr−1 for the time with maximum H. rhamnoides coverage. Our results suggest that local reactions of emissions to abrupt climate change could have been considerably faster than the overall atmospheric concentration changes observed in polar ice. Nitrogen enrichment of soils due to the presence of symbiotic N-fixers during early primary succession not only facilitates the establishment of vegetation on soils in their initial stage of development, but can also have considerable influence on biogeochemical cycles and the release of reactive nitrogen trace gases to the atmosphere.

Justification: I chose this article because I want to learn more about chemical emissions into the environment/certain ecosystems. What spiked this interest was first discovering that methane could actually form bubbles under the ice (people have been known to even pop them) and methane is being released into colder environments from permafrost thawing. I want to learn about what other chemicals are being released and what harm or good this is doing.

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