Vol18 No.2: 323-337
【Title】Characteristics of the active-layer under the China-Russia Crude Oil pipeline
【Author】SERBAN Mihaela1 ; LI Guo-yu1,2*; SERBAN Raul-David1;. WANG Fei1,3; FEDOROV Alexander4 ; VERA Samsonova4 ; CAO Ya-peng1,3 ; CHEN Peng-chao5 ; WANG Wei6
【Addresses】1 State Key Laboratory of Frozen Soils Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; 2 Da Xing'anling Observation and Research Station of Frozen-Ground Engineering and Environment, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Jiagedaqi 165000, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China; 4 Melnikov Permafrost Institute, SB RAS, Yakutsk 677010, Russia; 5 PetroChina Pipeline Company, Langfang 065000, China; 6 Jiagedaqi Oil and Gas Transmission Sub-company, PetroChina Pipeline Company, Jiagedaqi 165000, China
【Corresponding author】LI Guo-yu
【Citation】Serban M, Li GY, SerbanRD, et al. (2021) Characteristics of the active-layer under the China-Russia Crude Oil pipeline Journal of Mountain Science 18(2). https://doi.org/10.1007/s11629-020-6240-y
【Abstract】Active layer is a key component for permafrost environment studies as many subsurface biological, biogeochemical, ecological, and pedogenic activities prevail in this layer. This study focuses on active layer temperature monitoring in an area with sporadic permafrost at two adjacent sites along China-Russia Crude Oil Pipeline (CRCOP), North-East China. Site T1 is located in disturbed ground on the right-of-way (on-ROW) 2 m away from the center of the oil pipeline. T2 is located in a natural and undisturbed site, around 16.6 m off-ROW. Our objective was to study seasonal variability of the active layer depth and thermal regime from October 2017 to September 2018. The monitoring sites consist of soil temperature probes arranged in a vertical array at different depths at both sites. The following parameters were computed: number of isothermal days (ID), freezing days (FD), thawing days (TD), freezing degree days (FDD), thawing degree days (TDD), number of freeze-thaw days (FTD). The mean air temperature in the monitoring period reached -3.2°C. The temperature profile indicates that the maximum active layer thickness observed during the study period was 10 m at T1 and 2 m at T2. The majority of the soil temperatures were above or close to 0°C, resulting in great values of TDD, especially in the first 4 m depth. TDD for T1 were predominant and ranged between 600-1160°C·days (0-4 m depth) reflecting the influence of oil temperature from the pipeline. In T2 borehole FDD were predominant for all the soil layer depths resulting in less permafrost degradation. This comparison emphasizes the significant influence of vegetation removal and the dispersed heat from the pipeline on the active layer thickness.
【Keywords】Soil thermal regime; Permafrost; China-Russia Crude Oil Pipeline; Active layer