Distribution And Transportation Of Particulate Terrigenous Organic Matter In The Changjiang Estuary And Adjacent Region

In order to investigate the distribution and transportation of particulate terrigenous organic matter in the extraordinary flood Changjiang, Changjiang Estuary and adjacent region, suspended particulate matters(SPM) in Changjiang, Changjiang Estuary and East China Sea shelf were collected and had been measured for grain size, particulate organic carbon content(OC%), chlorophyll a(Chl-a), stable carbon isotopes(δI3C) and lignin phenols.The result showed that source and composition of particulate organic matter in the extraordinary flood Changjiang had a certain temporal and spatial distribution. Upper reach samples had low OC%and high A8value indicated that oil from the upper reach and C3plant detritus were the main source of particulate organic matter. Oil from the middle-low reach and phytoplankton’s production was the main source for the middle-low reach samples. On the contrary, phytoplankton’s production was the main source for the tributary(Dongtinghu, Poyanghu and Hanjiang). In contrast to the normal and drought year, flood year’s particulate organic matters had been highly degraded with higher (Ad/Al)v value. Furthermore, there was no big difference of source, composition and content of the particulate matter in surface and bottom layer for the reason of the large discharge.Salinity, TSM(total suspended matter) concentration and TMZ(turbidity maximum zone) were the important factors influence the particulate organic matter’s distribution in the Changjiang Estuary and adjacent region during summer. As salinity increase, the contribution of terrigenous particulate organic matter relative to marine particulate organic matter gradually decreased. Decreased concentrations of total suspended particles(TSM), reducing the turbidity of the water, improving the phytoplankton live production, increase the relative contribution of the source of marine particulate organic matter. Mineral constituent, microbial degradation and in situ production were major factors of the constituent and the character of particulate lignin during the delivery from Changjiang to the sea. Lignin indexes combined with POC/Chl a ratio indicated that influence of particulate organic matter from the turbidity maximum zone (TMZ), but confined within the TMZ only.The distribution and content of particulate matter in the East China Sea shelf varied with the seasonal change. In summer, there were high content particulate lignin and woody tissues of angiosperms source. On the contrary, low content particulate lignin and herbaceous tissues of angiosperms source was the major characteristic of the spring, showed that Changjiang Diluted Water (CDW) was the main factor to control the distribution of the particulate terrigenous organic matter in the East China Sea shelf water. Estuary as a border area of land and sea interaction, it was very important for terrigenous particulate organic matter delivery from river to the sea. After estuary, the content of particulate lignin decreased fast and various index (P/(V+S), DHBA, S/V,(Ad/Al)v, Pn/P) also were changed indicated that estuary had played a role to transform particulate terrigenous organic matter’s characteristic. Using Lig6as a tracer to trace the effection by the Changjiang diluted water indicated that the contribution of terrigenous POM was very low at the distance of300km off the mouth.