Particle flux at mooring sites in the Pacific Ocean (Table 1)@en

In order to understand the vertical transport of particulate matter, suspended and settling particles were collected along a meridional transect between 46°N and 35°S and an equatorial longitudinal transect between 135°E and 175°E in the Pacific. The low COrganic/N atomic ratios (<8.2) of suspended particulate organic matter (OM) and good correlation between particulate organic carbon (OC) and chlorophyll-a confirmed that the suspended particulate OM in the surface water was mainly produced by phytoplankton. Only 0.1–3.2% of primary production was transported to 1.3 km water depth in the boreal central Pacific. All data on settling particles (excluding deep trap data) showed strongly positive correlation between total mass and OM fluxes with high correlation factor of 0.93. Biogenic opal-producing plankton, mainly diatoms were responsible for most of the vertical transport of particulate OM in association with higher COrganic/CCarbonate ratios in the subarctic and equatorial hemipelagic regions in the Pacific. This vertical transport of settling particles potentially works as a sink of CO2. In the transition zone during the May 1993, large difference between PCO2 (<300 µatm) in the surface water and pCO2 (340 µatm) in the atmosphere was actually due to enhanced particulate OM flux. Since the deep water of the Pacific is enriched in CO2 and nutrients, upwelled seawater may tend to release CO2 to the atmosphere. However, higher production of particulate matter could reduce the partial pressure of CO2 in the surface water. Also terrestrial nutrients' inputs in the western equatorial Pacific have potential for the reduction of CO2 in the surface water.为厘清颗粒物的垂直输运机制，研究人员在太平洋北纬46°至南纬35°的经向断面，以及东经135°至175°的赤道纵向断面上，采集了悬浮颗粒与沉降颗粒样品。悬浮颗粒有机质（suspended particulate organic matter, OM）的有机碳/氮原子比值偏低（<8.2），且颗粒有机碳（particulate organic carbon, OC）与叶绿素a（chlorophyll-a）之间呈现显著正相关，这证实表层水体中的悬浮颗粒有机质主要由浮游植物合成。北太平洋中部海域仅0.1%~3.2%的初级生产力（primary production）被输运至1.3 km水深处。所有沉降颗粒数据（深海捕获器数据除外）均显示，总质量通量与有机质通量呈极强正相关，相关系数高达0.93。生源硅质浮游生物（主要为硅藻）主导了太平洋亚北极与赤道半深海区域内绝大多数颗粒有机质的垂直输运过程，该区域同时表现出较高的有机碳/碳酸盐比值。沉降颗粒的这种垂直输运过程可作为二氧化碳（CO₂）的汇。1993年5月的海域过渡带中，表层水二氧化碳分压（PCO₂ <300 µatm）与大气二氧化碳分压（pCO₂=340 µatm）存在显著差值，该现象实则由颗粒有机质通量升高所致。由于太平洋深层水体富含二氧化碳与营养盐，上升流海水易向大气释放二氧化碳。然而，颗粒物的高生成量可降低表层水体中的二氧化碳分压。此外，西赤道太平洋的陆地营养盐输入也具备降低表层水二氧化碳分压的潜力。