Just Add Water and Salt: the Optimisation of Petrogenic Hydrocarbon Biodegradation in Soils from Semi-arid Barrow Island, Western Australia

Abstract

We investigated the potential of soil moisture and nutrient amendments to enhance the biodegradation of oil in the soils from an ecologically unique semi-arid island. This was achieved using a series of controlled laboratory incubations where moisture or nutrient levels were experimentally manipulated. Respired CO 2 increased sharply with moisture amendment reflecting the severe moisture limitation of these porous and semi-arid soils. The greatest levels of CO 2 respiration were generally obtained with a soil pore water saturation of 50-70%. Biodegradation in these nutrient poor soils was also promoted by the moderate addition of a nitrogen fertiliser. Increased biodegradation was greater at the lowest amendment rate (100 mg N kg −1 soil) than the higher levels (500 or 1,000 mg N kg −1 soil), suggesting the higher application rates may introduce N toxicity. Addition of phosphorous alone had little effect, but a combined 500 mg N and 200 mg P kg −1 soil amendment led to a synergistic increase in CO 2 respiration (3.0×), suggesting P can limit the biodegradation of hydrocarbons following exogenous N amendment.

Citrate and malonate increase microbial activity and alter microbial community composition in uncontaminated and diesel-contaminated soil microcosms

“…The rapid increase in soil respiration with the addition of citrate is in accordance with previous studies and is indicative of the ability of the soil microbial community to quickly mineralize carboxylates (Evans, 1998;van Hees et al, 2002;Jones et al, 1996). It implies a fast turnover rate of carboxylates in soils, which is consistent with van Hees et al (2005), who estimated a mean residence time for carboxylates of between 2 and 70 h in the top mineral horizons, equating to a turnover of up to 10 times a day (van Hees et al, 2005).…”

“…Additionally, whilst studies have examined the microbial biodegradation of carboxylates in contrasting soil types (Fujii et al, 2010(Fujii et al, , 2012Hashimoto, 2007;Jones and Darrah, 1994), soil horizons (Evans, 1998;van Hees et al, 2002) and with variations in the initial pH of the organic acid applied (Ström et al, 2005), as far as we are aware, there are no studies examining in detail the biodegradation of carboxylates, and their effect on the microbial community, in soils contaminated with PHCs.…”

Root Exudation: The Ecological Driver of Hydrocarbon Rhizoremediation

“…Nutrients (nitrogen, phosphorus) have also been reported to be very important for hydrocarbon biodegradation [111][112][113]. The optimum nutrient content has been found to follow a C:N:P ratio of 100:10:1 [17,114]. However, excessive nutrient concentrations can also have negative effects, especially on aromatics, and inhibit hydrocarbon biodegradation [113,[115][116][117].…”

Autochthonous bioaugmentation to enhance phenanthrene degradation in soil microcosms under arid conditions

“…Although bioremediation is a promising technology to clean up hydrocarbon-contaminated sites, its potential on semiarid or arid soils has not been explored yet (Tibbett et al 2011). Tibbett et al (2011) showed that in tropical arid environments, soil moisture may be the rate-limiting abiotic parameter governing alkanes biodegradation.…”

“…Tibbett et al (2011) showed that in tropical arid environments, soil moisture may be the rate-limiting abiotic parameter governing alkanes biodegradation. In addition, the response to moisture amendment clearly demonstrated the importance of maintaining soil moisture at appropriate levels in any bioremediation scheme in arid environments.…”