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4593016 
Journal Article 
MONITORED NATURAL ATTENUATION FOR CRUDE OIL-BEARING SOIL: EVALUATION OF OIL BIODEGRADABILITY AND TOXICITY FOR LONG TERM CONTAMINATION 
Millioli, VS; Servulo, EFC; Sobral, LGS; Denize, DdeC; HELMHOLTZ CENTRE ENVIRONMENTAL RESEARCH-UFZ 
2008 
1118-+ 
WOS:000278009000159 
Natural attenuation relies on natural processes in soil and groundwater without human intervention and as a result of interactions of chemical, physical and biological processes This technology, usually, requests a long period of time to fulfill the directives of the environmental legislation. Whenever there is no risk to justify an accelerated treatment in contaminated sites the best thing to do is only to monitor some conditions as toxicity, mobility, volume or concentration of those pollutants in soils or groundwater. In this work the natural attenuation was monitored by the biodegradation and/or toxicity of the crude oil contaminated soil in a long period of time, through the analyses of TPH (Total petroleum hydrocarbon) and toxicity tests being used methodologies as dehydrogenasic activity, seed germination with Lactuca sativa and mortality of the earthworms with Eisenia fetida. Besides those TPH analyses and toxicity, other tests were conducted such as microbial population, pH, phosphorus (P) and Nitrogen (N) contents in the soil. The Assays were conducted by simulating the natural attenuation of contaminated soil. The soil contaminated with 5% of crude oil was put in a Perspex glass lysimeters with dimensions of 40 x 30 x 25cm, filled out in the bottom with different sizes of rock and an outlet pipe for draining the percolated water originated from the rain. The assays were monitored during 9 months and at the end of this period, it was verified about 25 of TPH removal in the soil as well as a decrease of the toxicity through the germination tests and mortality of the earthworms. Regarding to the other accomplished tests, it was verified that some parameters as pH and N were practically constant, and there was a small increase in the quantification of the native microbial population as well as in the dehydrogenasic activity and there was a small decrease on phosphorus content in the soil along the time. 
petroleum; bioremediation; soil; toxicity