Distribution and source analysis of hydrocarbons in sediments of Zhenzhu Bay Mangrove Wetland in Guangxi

To study the distribution characteristics and sources of hydrocarbons in the surface sediments of Zhenzhu Bay Mangrove Wetland in Guangxi, South China, 13 surface sediments of the wetland were collected in September 2021 to test and analyze the normal alkanes and polycyclic aromatic hydrocarbons (PAHs) in the sediments. Results show that the content of n-alkanes (dry weight) in the surface sediments of the area was 362.17～10 390.72 ng/g, and the content of PAHs (dry weight) was 7.76～28.06 ng/g, which was generally at a low level. The n-alkanes were mainly come from terrestrial non-floating herbs and were not polluted by petroleum and its derivatives; PAHs were characteristic of dominant macromolecular compounds as shown in the characteristic parameter ratio method. The potential sources of PAHs were pertroleum, pertroleum combustion, and coal vegetation combustion as indicated in the isomer ratio method. In addition, the main source of PAHs was mixed combustion source (>52%), followed by oil pollution source, as revealed by the principal component analysis/linear regression analysis model (PCA-MLR). At last, the ecological risk of PAHs was at a low level as determined in the ecological risk evaluation of PAHs by the effect interval low/median method.