The Environmental Geochemistry of Aliphatic Hydrocarbons in Environmental Media from Typical Fossil Fuel Extraction Areas in China

典型化石燃料開采區環境介質中脂肪烴的環境地球化學研究

Student thesis: Doctoral Thesis

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Award date25 May 2020

Abstract

Aliphatic hydrocarbons are abundant in fossil fuels. They can be released into the environment during the process of exploitation and utilization of fossil fuels, posing serious threats to aquatic organisms and human health. Therefore, the primary objective of the present research is to understand the environmental geochemistry of aliphatic hydrocarbons in typical fossil fuel extraction areas, which is of great significance for developing effective countermeasures to reduce the adverse effects of anthropogenic activities on the surrounding ecological environment.

In the petroleum-producing area, 46 soil samples, 21 surface sediment samples, a sediment core and eight fish species from the Yellow River Delta were collected. In the Anhui coal-mining area, 54 surface sediment samples and five sediment cores from the Huai River were also collected. Based on the experimental analysis methods such as sonication extraction, Soxhlet extraction, microwave-assisted solvent extraction, GC-MS analysis, 210Pb dating and stable isotopes analysis (δ13C and δ15N), and data analysis methods such as diagnostic ratios and principal component analysis-multiple linear regression analysis, the spatial and temporal distribution characteristics, contamination levels, homolog profiles, source apportionments, historical sedimentary records and trophic transfer of aliphatic hydrocarbons in aquatic environments from typical fossil fuel extraction areas were investigated. The major findings of the present research work are as follows: (1) Despite the presence of fossil fuel contamination in soil and sediments from the petroleum-producing area and coal-mining area, the contamination levels were relatively low when compared with other areas in the world. Different distribution patterns of n-alkanes and the dramatic variation of n-alkane concentrations were observed among different species from the petroleum-producing area, probably caused by different habitats, feeding preferences and elimination mechanisms of n-alkanes. (2) In soil and sediments from the petroleum-producing area and coal-mining area, petroleum hydrocarbons, fossil fuel combustion and vehicle exhaust were the main anthropogenic sources of aliphatic hydrocarbons, while submerged/floating macrophytes, emergent plants and terrestrial higher plants were the main natural sources. The quantitative contributions of aliphatic hydrocarbon sources in surface sediments from the Huai River (Anhui section) were estimated as follows: 21.8% terrestrial higher plants, 24.1% algae and photosynthetic bacteria, 14.9% submerged/floating macrophytes, 23.5% fossil fuel combustion and 15.7% petroleum hydrocarbons. And the anthropogenic contributions of aliphatic hydrocarbons accounted for 37.7 to 86.2% in sediments from Huai River (Anhui section) during 1955-2014. (3) The temporal variations of n-alkanes in dated sediment cores successfully archived the anthropogenic activities and side-effects of China's rapid economic development in typical petroleum-producing area during 1925-2012 and coal-mining area during 1955-2014. (4) Analysis of diagnostic ratios indicated the presence of petroleum hydrocarbons in studied fish species, and natural n-alkanes are probably more easily eliminated than anthropogenic n-alkanes from fish muscle tissue. Moreover, trophic magnification factor (TMF) values ranged from 0.656 to 1.150, indicating trophic dilution of aliphatic hydrocarbons. The octanol/water partition coefficient (KOW) is probably an important factor affecting the accumulation of n-alkanes in organism-sediment systems and their trophic transfer in food webs.

    Research areas

  • Yellow River Delta, Huai River, Aliphatic hydrocarbons, Historical sedimentary record, Trophic transfer