Multilayer Distribution Of Carbon Dioxide System In The Surface Water Of The Yellow Sea In Spring

The ocean is a very important connection in global carbon cycles, which plays a leading role in carbon exchange and transfer between the lithosphere, seabed sediment, biosphere and atmosphere.The sea surface microlayer (SML) is a thin layer situated between the ocean and atmosphere, which is the inevitable way of materials exchange in the sea-air interface. Because of its unique physical, chemical and biological properties, the SML have an important and direct effect on biogeochemical cycles in ocean, materials fluxes in sea-air interface and global climates. In this article the SML is introduced to the carbon dioxide cycle in sea-air interface of the marginal sea in China. In addition, the key study is put upon the carbon dioxide system including DIC, Alk, pH and pCO2 in SML, SSL and SL of the sea surface waters. In this article, through the study of surface water, we will do our endeavor to make more perfections and complementarities of the carbon dioxide system in the surface water of Yellow Sea and the"SML pump".This work includes: (1) The SML pump is introduced to the carbon dioxide cycle in sea-air interface of the marginal sea in China. In addition, systematical multilayer studies on carbon dioxide system including DIC, Alk, pH and pCO2 in SML, SSL and SL of the sea surface waters in the Yellow Sea have been made. (2) Comparing the results of April, 2006 to March and May, 2005, we hope to find the variation regularities of them in a long time.The main results are summarized as following:1. Multilayer horizontal distributions of DIC, Alk, pH and pCO2 in the surface waters of the Yellow Sea The horizontal distributions also show that DIC and Alk become higher from ocean to coast. It maybe because the influence of waste input from land, the weaker exchange ability between the coast and ocean, the effect of"Qingdao Cold Water Mass". In addition, the positive relationship between DIC and Alk is found clearly.The horizontal distribution of pH and pCO2 is opposite, and the pH value is become lower from coast to the ocean. There is a lower pH value area around A1 and A2, and a higher pCO2 value area appeared accordingly. It maybe becomes the influence of acid rain and"Yellow Sea Warm Current". In addition, there is a higher pH value area around G11, and a lower pCO2 value area appeared accordingly. The mainly probability is the affection of the biological activities. It shows that pH and pCO2 are in a clearly negative relationship.2. Multilayer vertical distributions of DIC, Alk, pH and pCO2 in the surface waters of the Yellow SeaThere is a same vertical change regularity of DIC and Alk, and they both become lower in a turn of SML, SSL and SL. That is to say DIC and Alk show an obvious enrichment phenomenon in SML compared to their data in SSL and SL, whose enrichment factor (EF=DIC, Alk(SML)/DIC, Alk(SSL)或(SL)) is higher than 1. DIC and Alk show a"non-linearity distribution"regularity from SML to SL rather than the normal linearity distribution. It maybe because that the co-effect of the multilayer characteristic of SML and the abnormal Gibbs absorption in SML.There is an opposite vertical change regularity of pH and pCO2, and pCO2 values become lower from SML to SL. It can prove that pH and pCO2 is in a negative relation. All the pCO2 values of the Yellow Sea in April are less than 370μatm, that is to say, the Yellow Sea in April is a"sink"of the atmospheric CO2. In addition, it is found that the pH curve turn to the left direction, which is the direction of pH becomes lower. 3. Multilayer temporal distributions of DIC, Alk, pH and pCO2 in the surface waters of the Yellow Sea(1) Diurnal variation: the diurnal variation regularities of DIC, Alk, pH and pCO2 in SML, SSL, SL of the sea surface waters in the Yellow Sea in spring are as following: DIC, Alk, pH and pCO2 all have obvious multilayer distribution regularity in the SML, SSL and SL. There are a same multilayer distribution regularity in DIC and Alk, and an opposite distribution regularity in pH and pCO2.DIC and Alk are both enriched in SML. The same multilayer distribution regularity of DIC and Alk is a study feature in the article. DIC and Alk appear the maximum around 02:00~03:00, and appear the minimum around 14:00~15:00. The distributions of DIC and Alk show a"single-peak"phenomenon.The pH maximum values appear around 14:00~15:00, and the pH minimum values appear around 02:00~03:00. The pCO2 maximum values appear around 02:00~ 03:00, and the pCO2 minimum values appear around 14:00~15:00.The distributions of pH and pCO2 show a"single-peak"phenomenon.(2) Yearly variation: DIC, Alk and pCO2 all become lower in a turn of March, April and May in the SML, SSL and SL, but the pH becomes lower in a turn of May, April and March in the SML, SSL and SL.4. Multilayer distributions between DIC, Alk, pH, pCO2 and other parameters in the surface waters of the Yellow Sea(1) The relationships of DIC, Alk, pH and pCO2 versus temperature/salinity: there is an obvious negative relationship of DIC and Alk versus temperature/salinity in spring. The change trend of DIC versus temperature is more obvious than the trend of Alk versus temperature. There is a positive relationship of pCO2 versus temperature/salinity, but the pH is opposite. Because of the influence of the"Yellow Sea Warm Current", there is a negative relation of pH and pCO2 versus salinity.(2) The relationships of DIC, Alk, pH and pCO2 versus longitude/latitude: There is an obvious negative relationship of DIC, Alk versus longitude, but there is no obvious relationship of DIC, Alk versus latitude. The pH values become lower with the longitude enhancing, but the pCO2 is opposite. There is a positive relationship of pH versus latitude, but the pCO2 and latitude is in an opposite relationship. There is a distribution regularity of"high latitude and low pCO2". In this article, the mainly reason of"high latitude and low pCO2"is the effect of temperature change.(3) The relationship between measurement and calculation of DIC, Alk, pH and three calculation values of pCO2: There is a well positive relationship between the calculation and measurement of DIC, Alk, pH. The relationship among the three calculation pCO2 values also show a good consistency.5. Study of carbon dioxide fluxes (FCO2)In this article it is believed that the FCO2 calculated on the basis of the pCO2 data in SML is more reliable than that on the basis of that in SL. The fluxes are as following: As a"sink"of atmospheric carbon dioxide, the FCO2 of the Yellow Sea in spring is about -4.703 mol?m-2?a-1 (or -5.36×106 t C).Comparison of 2005 and 2006, as a"sink"of atmospheric carbon dioxide, the average of carbon dioxide flux of the Yellow Sea in spring is about -5.639 mol?m-2?a-1 (or -6.43×106 t C).