Temporal And Spatial Distribution Of Organic Carbon And Its Influence Aspects In Huanghe Estuary

Particulate and dissolved organic carbon concentrations were measured in the mixing zone of Huanghe river and its estuary, during two cruises in August and September. In the dry reason, surface and bottom samples were collected simultaneously at ten locations; Three ships were used to collect samples in three lines along the estuary in the wet reason. Temperature, pH and Alk were measured in situ laboratory; The samples for other parameters were stored carefully until being measured.1.The analysis of organic and inorganic carbon variation with salinity in fresh-sea water mixing experiment in laboratory.Base on two aspects which result in organic and inorganic carbon variation with salinity, particulate form turn to dissolved form and seawater dilution, when the salinity is below 5%o, the aspect of particulate form turn to dissolved form is dominant, so DOC don't exhibit a conservative behavior in these estuarine systems, but when salinity is above 5%o, with the dilution of seawater riverine DOC closely decrease with salinity increase.2. The distributions of DOC and POC in Huanghe estuary in different seasons.DOC and POC have almost same transport ways from river mouth to margin in dry season: one part move to NE along the riverine water, others turn to South and flow into Laizhou estuary. In wet season, DOC and POC mainly diffuse to South. POC and DOC content in the estuary decrease along the estuary and it is higher in South than in North at both seasons. The distributions of DOC and POC are influenced by physical process more the biological contributions. There is a delay time when tidal water affect the distribution of DOC and POC in Huanghe estuary.3. The relationship between POC and TSS, POC and DOC in every season.In general, the dry season distribution of POC follows closely that of TSS, however, the POC content in wt.% increase with decreasing turbidity; In contrast, POC% is lowest when TSS is about 70 mg/L in wet season. When TSS is more than 70 mg/L, POC origin from terrestrial, otherwise, POC is dominantly of aquatic production because turbidity decreasing result in activity of aquatic production. The average ratios of DOC/POC vary 4.4 from 5.5 in wet and dry seasons, which are between ocean (about 10) and rivers (about 1.5). The content of DOC release from sediment isn't enough to influence the distributions of bottom DOC.4. Transport flux of DOC and POC in Huanghe estuary in July to September.We estimated the flux of DOC and POC is 2.43 X 109gC and 2.76 X 109gC in August which only account for 1% and 0.1% in annual organic carbon flux. In September, 1.2X 1010gC and 57X 10ngC is measured with the form of DOC and POC flow to the sea with water discharge. By the river water-seawater mixing experiments which were designed by ourselves, DOC exhibits a very conservative behavior to salinity especially the salinity is more than 5%o.