243 Analele Universităţii din Oradea, Fascicula Protecţia Mediului Vol. XX, 2013 NATURAL ATTENUATION FACTOR IN ENHANCING NATURAL ATTENUATION OF CRUDE OIL ON A CONTROLLED POLLUTED HAPLIC LUVISOL IN ORADEA, ROMANIA Sabău Nicu Cornel*, Şandor Maria**, Brejea Radu* * University of Oradea, Faculty of Environmental Protection, 26 Gen. Magheru St., 410048, Oradea, Romania, e-mail: nsabau@uoradea.ro ** Agricultural Research and Development Station Oradea, 5 Calea Aradului St., Oradea, Romania, e-mail: scdaoradea@yahoo.com Abstract The biodegradation is the process used for the degradation of the pollutants from environment or for the reduction of their toxicity, through the usage of the living organisms, microorganisms and plants (phytoremediation), these acting through many mechanisms: phytoextraction, phytostabilization, rhizofiltation, phytodegradation and phytovolatilization. The natural attenuation is a process more complex than biodegradation, having a larger meaning, the reduction of the contaminants concentration being realized, moreover through the physical-chemical mechanisms, which can immobilize or decrease the pollutant concentration from environment (advection, dispersion, dilution, diffusion, volatilization, sorbtion/desorbtion, ion exchanges, abiotic complexing, etc.). It was defined the concept of enhancement of the natural attenuation, that refers to the measures taken for the initiation or intensification of the process of natural attenuation with the aim of the faster decrease of the pollutant concentration from environment. For the screening of the pollutants natural attenuation it is recommended the using of Natural Attenuation Factor (NAF), which provides information regarding the speed of the process development. The aim of this paper is the estimation of the Natural Attenuation Factor (NAF) of the crude oil from Suplacu de Barcău, under the conditions of the controlled polluted soil and different measures of Enhancing Natural Attenuation (ENA) through the administration of fertilizers, (manure, complex fertilizer and combinations of them) from the experimental field Oradea. Natural Attenuation Factor (NAF) has got values between 0,56 %/year, in the Natural Attenuation (NA) process of variants polluted with 3 % crude oil and 0,90 %/year for the Enhancing Natural Attenuation (ENA) process through organic and complex fertilization (manure x NPK). Key words: soil pollution, biodegradation, natural attenuation factor, fertilizing system. INTRODUCTION The main sources of soil pollution by hydrocarbons of different kinds are as follows: extractive industry, manufacturing, transport and refueling of vehicles. For the Romania’s conditions one considers that the main source of pollution is the extraction fields where the crude oil, waste oil and salt water spills caused historical pollution of nearly 50,000 hectares of land. In the west of the country, i.e. Bihor County, one inventoried an area surfacing roughly 200 hectares of land contaminated with oil residues within the oil extraction fields from Suplacu de Barcau, Marghita and Oradea near the Petrolsub refinery from Suplacu of Barcău (Sabău et al., 2011).