hide
Free keywords:
DIESEL FUEL; ASPERGILLUS-NIGER; HEXADECANE; STATE; BIODEGRADATION;
GLUCOSECO(2) evolution; Hydrocarbon; O(2) uptake; Oil pollution; Respiratory
quotient; Soil microbial respiration; Carbon isotope signature;
Abstract:
On the basis of CO(2) evolution rate, O(2) uptake rate, and (13)C isotopic signature of respired CO(2), the metabolic response to the addition of (13)C labelled n-hexadecane and palmitic acid each with supplementary nitrogen was studied for two topsoils, one under continuous agricultural management and the other under beech forest. The CO(2) evolution rate was immediately stimulated in the agricultural soil and the respiratory quotient (RQ) decreased from 0.8 to 0.4 mol CO(2) evolution rate per mol O(2) uptake rate, which was below the theoretically expected value of 0.65 and 0.70 for the degradation of n-hexadecane and palmitic acid, respectively. The microbial response was delayed in the forest soil, but developed better than in the agricultural soil throughout the subsequent 2-4 weeks. Consequently, the respiration rate returned earlier to the initial level for the beech forest soil and the delta(13)C of respired CO(2) and RQ approached values before hydrocarbon addition. Based on the link among respiration rates, RQ and (13)C-CO(2) value, the added oil-analogue compounds induced a more rapid response in the agricultural soil and were degraded more completely in the forest soil. We concluded that the resilience, which we defined here as the capacity of the soil microbiota to buffer perturbance and to reorganise in response to change resulting in a more desirable system, was higher in our forest soil than for the agricultural soil. (C) 2010 Elsevier Ltd. All rights reserved.
