Geochemistry Of Polycyclic Aromatic Hydrocarbons In The Seawater From The Northern South China Sea And Coastal Seawater, Xiamen

Trough the survey of open voyage of South China Sea,particulate and dissolved polycyclic aromatic hydrocarbons(PAHs) samples were obtained in Sep.of 2004,, 2005,2006.It's the first time to report concentrations,horizontal and vertical distribution pattern,source and annual trends,which helps the marine research make a great progress,from the coast to marginal sea.At the same time,4 voyages were taken in Jiulong estuary and West Sea of Xiamen to investigate the geochemistry behave and seasonal trends of PAHs.All the conclusions were showed as follows:The concentrations of particulate 16 PAHs(∑PAH) were 0.77～6.94 ng/L(2.80 ng/L in average),0.40～3.62 ng/L(1.33 ng/L in average),separately in Sep of 2004 and 2005.While concentration of dissolved∑PAH were 1.13～11.03 ng/L(4.24 ng/ L in average) in Sep of 2005.Horizontally,the concentrations of∑PAH were higher at the seashore and lower in the open sea,and with the distance from seashore increasing,the concentrations of∑PAH depressed regularly;Vertically,particulate organic matters could affect∑PAH distribution,it showed some correlation in this sea areas.There was a maximum at the depth of 50 meter.Compounds with 2～3 rings were dominate pollutants.The ratios,Phen/Ant and Fluo/Py were used to estimate the PAHs' source.They indicated that the source of PAHs in Northern SCS was the input of Pearl River. Separate stations in the open sea were affected by the oil fields exploitation.The distribution between particulate and dissolved phase behaved 5 rings＞4 rings＞3 rings＞2 rings,the same as the characters of the compounds.Differently from SCS,the concentrations of∑PAH in Jiulong estuary and West Sea of Xiamen,China,were much higher.The dissolved concentration of∑PAH were 333.2 ng/L～1 679.5 ng/L(839.6 ng/L in average),241.7 ng/L～1 837.8 ng/L (818.8 ng/L in average),91.1 ng/L～7 484.9 ng/L(3 528.3 ng/L in average), 1 011.8 ng/L～6 447.2 ng/L(3 369.5 ng/L in average) in spring,summer,autumn and winter,2006～2007,separately;While the particulate concentrations of∑PAH were ND～2 578.2 ng/L(1 048.1 ng/L in average),594.5 ng/L～1 913.0 ng/L (893.5 ng/L in average),774.8 ng/L～4 707.0 ng/L(2 412.2 ng/L in average), 2 120.4 ng/L～9 136.4 ng/L(4 788.7 ng/L in average).Horizontally,the concentrations of∑PAH were depressed as salinity increasing, that is from the estuary to the open sea,and there was an obvious falling trend in Jiulong estuary and West Sea,Xiamen.The high value appeared at river end and West Sea.This indicated that Jiulong estuary and West Sea were the main sources of the coast of Xiamen.Vertically,the export of particulate organic carbons and sediment resuspended could efeect PAHs concentrations.The distribution of PAHs with different rings and in different seasons varied obviously.In spring and summer,PAHs with low rings were transported by dissolved phase,while PAHs with high rings were by particulate in autumn and winter.These seasonal trends were similar to other estuaries and bays.Both particulate and dissolved PAHs,the lowest concentration occurred in summer,but the highest took place in winter.The main reason was the different precipitation.