Study On Speciation And Distribution Of Phosphorus In Waters And Sediments Of Tonkin Gulf In Summer

Based on the environmental investigation during July～August,2006 in Tonkin Gulf,the speciation of phosphorus in the waters and in the surface sediment were determinated.By analyzing the distribution of different speciation of phosphorus and relationship between environmental factors and different speciation of phosphorus in the waters and in the surface sediment,the source of phosphorus,and its source,transportation and transformation were explored.The results can be summarized as follows:(1) The average concentrations of dissolved inorganic phosphorus (DIP),dissolved organic phosphorus(DOP),particle phosphorus(PP) and the total phosphorus(TP) respectively were 0.32μmol/L,0.86μmol/L,0.53μmol/L and 1.74μmol/L in the sea water.DIP,DOP and PP accounts for(23%±4%),(31%±16%) and(46%±23%) of TP.DIP and the PP can be transformed into each other,and the PP can be transformed into DOP.(2) DIP was mainly influenced by terrestrial inputs in the euphotic zone(above 10 meters).But below the euphotic zone(below 10 meters) DIP were mainly produced in the biogeochemical process;the concentrations of DIP were gradually increased with depth.The contents of DOP were affected by the input of external waters, especially the organic matter from Vietnamese coastal water mission and Qiongzhou Strait aisle water.The contents of DOP had small vertical gradient in the 0～30 meters layer,and the vertical distribution was uniform.The contents of DOP increased with depth below 30meters.The concentrations of PP were apparently influenced by the inputs of particulate from Qiongzhou Strait aisle.The contents of PP were decreased with depth.The concentrates of TP was influenced by the terrestrial inputs.The contents of TP showed a slight increase with depth increasing.(3) The ratio range of DIN to DIP varied from 0 to 12.57,with(1.62±2.10) as the mean value.The ratio of DIN to DIP of more than 50 percent of the stations less than 1.Moreover,it was far lower than the Redfield ratio.The restrictive nutrient was DIN in Tonkin Gulf.(4) The average concentration of TP_S was 377.91μg/g,and average concentration of inorganic phosphorus(IP_S) was 256.91μg/g,its accounts for 66.97%±7.70%of TP_S The average concentrations of Loosely absorbed inorganic phosphorus(Ads-P),Iron-bound inorganic phosphorus(Fe-P),Organic phosphorus(OPs),Authigenic CaCO₃-bound inorganic phosphorus(Ca-P),Detrital apatite phosphorus(De-P) and Portland phosphorus(SIF-P) separately were 5.39μg/g,79.82μg/g,64.28μg/g,47.87μg/g,123.83μg/g and 56.36μg/g,Obviously, De-P＞Fe-P＞OPs＞Ca-P＞SIF-P＞Ads-P.(5) The contents of TP_S were mainly controlled by ocean internal "biological effect s" and "Grain effects" of sediment,which was weakly influenced by terrestrial inputs.Temperature(t_m),salinity(S) and sediment particle grain(GSL) were the important affecting factors of Ads-P,which mainly come from aquatic particles. Correlative analysis between environmental factors and different speciation of phosphorus in bottom sea water show that salinity has negative correlated with Fe-P, OP_S and SIF-P,which suggested Fe-P,OP_S and SIF-P were mainly controlled terrestrial inputs.Ca-P and DIP was negatively correlated,and Ca-P was the sink of DIP in the bottom waters.Ca-P and De-P were positively correlated with bottom water salinity,which suggested Ca-P and De-P had obvious characteristics of ocean sediment.(6) The "active phosphorus" of the potential "bio-available phosphorus"—Ads-P,OP_S and Fe-P accounts for 39.90%±8.07%of TP_S in Tonkin Gulf;The"inert phosphorus" of not participating in the biochemical cycle—SIF-P,Ca-P and De-P accounts for 60.09%±8.07%of TP_S in Tonkin Gulf。...