[Evaluation on biodegradability of hydrocarbon biomarkers in two crude oils under laboratory conditions]

Biodegradabilities of several hydrocarbon biomarker groups, including isoprene, hopanes and steranes in a medium-crude oil BZ34-1 and a heavy-crude oil SZ36-1 from offshore, were determined under laboratory conditions. The results of GC-MS analysis showed that isoprene biomarkers such as pristane and phytane in both crude oils degraded obviously in 60-day experiment period. The degradation ratios of pristane and phytane in the medium-crude oil BZ34-1 reached 20.2% and 15.0%, respectively; while those in the heavy-crude oil SZ36-1 reached 95.6% and 75.4%, respectively. Pristane and phytane in the heavy-crude oil SZ36-1 were degraded in the early period of biodegradation, but these two biomarkers in the medium-crude oil BZ34-1 were degraded in middle and late biodegradation phases. However, hopanes and steranes in the both oils were not biodegraded obviously during the whole period. These results indicated that pristane and phytane could be used to evaluate bioremediation efficiency in the early biodegradation phase for light or medium oils, while hopanes and steranes could be used to evaluate bioremediation efficiency within the whole given experiment process.