海洋降水中无机离子浓度及湿沉降通量——中国海及西北太平洋降水的研究

摘要

The precipitation samples were collected in the Yellow Sea, the East China Sea, the South China Sea and the Northwest Pacific Ocean during two-period of cruise in spring and summer of 2016. The concentrations of Cl-, NO3-, SO42-, PO43-, Na+, NH4+, K+, Mg2+ and Ca2+ were measured by ion chromatograph, and the wet deposition fluxes of these ions, as well as their impact on marine primary productivity, were estimated. Considering the common features such as high concentration of sea salt ions and comparable major ions among the East China Sea, the South China Sea and the Northwest Pacific Ocean, the precipitation over the wide ocean was likely dominated by the localized ocean effect. The major ions in the precipitation were Cl-, Na+, SO42- and Mg2+ over the Northwest Pacific Ocean, NO3-, SO42-, Ca2+ and Cl- over the Yellow Sea and Cl-, Na+, NO3- and SO42- over the East China Sea and South China Sea. The magnitude of the mean concentration (mmol/L) of total ions in precipitation among the four sampling regions was in the order of the Northwest Pacific Ocean (1.27) > the South China Sea (0.53) > the East China Sea (0.40) > the Yellow Sea (0.31). Inorganic nitrogen mainly existed in the form of nitrate and the contribution of nitrate to total inorganic nitrogen continues to increase during the air mass transport from the land to ocean. The wet deposition fluxes[mg/(m2·h)]of Cl-, NO3-, SO42-, PO43-, Na+, NH4+, K+, Mg2+ and Ca2+ were in range of 3.47~451.43, 0.60~49.36, 1.13~124.02, 0.0015~0.094, 1.21~383.37, 0.06~7.57, 0.25~28.86, 0.17~47.39and 0.37~27.24, respectively. In regions near the emission source and abundance of precipitation, the wet deposition flux of major ions was relatively high. The inorganic nitrogen and phosphorus in precipitation was able to provide new productivity, approximately accounting for 0.13‰~32.08% of the primary productivity per hour on average.%于2016年春夏季搭载航次采集了黄、东、南海及西北太平洋的海洋降水,用离子色谱法测定了其中的Cl-、NO3-、SO42-、PO43-、Na+、NH4+、K+、Mg2+和Ca2+离子浓度,并计算了其湿沉降通量及对海洋初级生产力的影响.结果表明,海洋降水样品主要受海洋影响,海盐离子浓度较高且不同海域主要离子类似;西北太平洋主要离子为Cl-、Na+、SO42-、Mg2+,黄海主要离子NO3-、SO42-、Ca2+、Cl-,东海和南海主要离子均为Cl-、Na+、NO3-、SO42-.海洋降水中总离子浓度(mmol/L)的空间分布为西北太平洋(1.27)>南海(0.53)>东海(0.40)>黄海(0.31).海洋降水中无机氮主要以硝态氮的形式存在,在气团由陆地向海洋传输的过程中,硝态氮在无机氮中的贡献也不断增加.Cl-、NO3-、SO42-、PO43-、Na+、NH4+、K+、Mg2+和Ca2+的湿沉降通量[mg/(m2·h)]范围分别是:3.47~451.43、0.60~49.36、1.13~124.02、0.0015~0.094、1.21~383.37、0.06~7.57、0.25~28.86、0.17~47.39和0.37~27.24.在靠近源区、降水量多的区域主要无机离子的湿沉降通量较高.估算结果显示,每小时降水所含氮磷可为各海域提供占初级生产力0.13‰~32.08%的新生产力.