Distribution of sterol compounds in the northern East China Sea influenced by the low salinity water mass

Abstract

Sterol distributions in the dissolved phase and suspended particulate matter were investigated in the off-shore East China Sea influenced by the low salinity water mass. Total sterol concentrations in 16 water samples ranged from 663 to 5690 pg/L in the dissolved phase and 3200 to 31,900 pg/L in the suspended particulate matter. In the overall sterol composition, marine sterols dominated with 66% in the dissolved phase and 71 % in the suspended particulate matter. The dominant sterols in dissolved phase were β-sitosterol (25%), brassicasterol (24%), cholesterol (19%) and fucosterol (13%), and in the suspended particulate matter, brassicasterol (21%), cholesterol (20%), β-sitosterol (16%), and cholestenone (14%). Typical sewage markers such as coprostanol, α-cholestanol, epicoprostanol, and coprostanone were absent. However, molecular signatures of allochthonous terrestrial plants were still visible at such distances. There was a relationship between low salinity water mass in the East China Sea and terrestrial sterols, suggesting the influence of Yangtze River in transporting land derived organic matter to the off-shore East China Sea.0 pg/L in the dissolved phase and 3200 to 31,900 pg/L in the suspended particulate matter. In the overall sterol composition, marine sterols dominated with 66% in the dissolved phase and 71 % in the suspended particulate matter. The dominant sterols in dissolved phase were β-sitosterol (25%), brassicasterol (24%), cholesterol (19%) and fucosterol (13%), and in the suspended particulate matter, brassicasterol (21%), cholesterol (20%), β-sitosterol (16%), and cholestenone (14%). Typical sewage markers such as coprostanol, α-cholestanol, epicoprostanol, and coprostanone were absent. However, molecular signatures of allochthonous terrestrial plants were still visible at such distances. There was a relationship between low salinity water mass in the East China Sea and terrestrial sterols, suggesting the influence of Yangtze River in transporting land derived organic matter to the off-shore East China Sea.