Composition and Distribution of Aliphatic Hydrocarbon Compounds and Biomarkers in Seafloor Sediments from Offshore of the Leizhou Peninsula (South China)

Yuan Gao; Yongqiang Han; Jia Xia; Jingqian Tan; Yao-Ping Wang; Sibo Wang

doi:10.1021/acsomega.1c03529

Composition and Distribution of Aliphatic Hydrocarbon Compounds and Biomarkers in Seafloor Sediments from Offshore of the Leizhou Peninsula (South China)

ACS Omega. 2021 Dec 10;6(50):34286-34293. doi: 10.1021/acsomega.1c03529. eCollection 2021 Dec 21.

Authors

Yuan Gao^{1

2

3}, Yongqiang Han^{4

5}, Jia Xia^{1

2}, Jingqian Tan¹, Yao-Ping Wang^{1

2}, Sibo Wang^{1

2}

Affiliations

¹ College of Chemistry and Environmental Science, Guangdong Ocean University, Zhanjiang 524088, China.
² Shenzhen Research Institute of Guangdong Ocean University, Shenzhen 518108, China.
³ Key Laboratory of Climate, Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong Province, Guangdong Ocean University, Zhanjiang 524088, China.
⁴ State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang 550081, China.
⁵ University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

The offshore of Leizhou Peninsula (LP, China), which contains unique ecosystems such as mangroves, seagrass beds, and coral reefs, is an environmentally sensitive area. For this reason, the levels of aliphatic hydrocarbon including biomarkers (hopanes, steranes) in the offshore seafloor sediments were analyzed in terms of their composition, distribution, and input sources and aimed to evaluate the extent of possible petroleum hydrocarbon contamination in the sediments of coastal areas. The total aliphatic hydrocarbons (TAH) fraction, the content of total n-alkanes (nC₁₄-nC₃₇) (∑n-alkanes), and content of hopane + sterane are in the range of 13.76-99.53, 1.22-8.33, and 0.02-0.23 μg/g dw, respectively. The presence of unresolved complex mixture (UCM) hydrocarbons hump and petrogenic steranes and hopanes in these seafloor sediments suggest that petrogenic sourced hydrocarbon inputs were present. The stations on the peninsula's southwest side had the lowest values of UCM/resolved aliphatic compounds (UCM/R) and UCM/n-alkanes. These findings suggest that seafloor sediments from the southwest offshore of the peninsula were likely contaminated by recently inputted petroleum hydrocarbons. The presence of relatively high ∑n-alkanes content in seafloor sediments from southwest offshore of the LP, combined with relatively low natural n-alkane ratios (NARs), indicates an increased influence of petrogenic hydrocarbons. The elevated levels of recent petrogenic hydrocarbon contamination in the sediments from the LP's southwestern offshore were likely related to petroleum exploitation in the Beibu Gulf's Maichen and Wushi sags.