Particulate amino acid and carbohydrates and particulate organic carbon and nitrogen in suspended and sinking organic matter from METEOR cruise M156@en

We collected in situ marine snow aggregates with a Marine Snow Catcher (MSC). The MSC allows studying the composition of suspended and fast-sinking organic matter from intact in situ formed aggregates (Riley et al. 2012). After deployment, the MSC was left vertically on deck for three hours, seawater containing suspended organic matter was collected from the top part of the MSC and fast-sinking organic matter was picked manually from the MSC base. The MSC was deployed within the mixed layer depth in the oxygen minimum zone (~400 m depth). Duplicate samples for particulate organic carbon (POC) and organic nitrogen (PON) were filtered onto pre-combusted (450 ◦C for 5 h) Whatman GF/F filters (25 mm, 0.7 µm) under low pressure (< 200 mbar). Filters were frozen at −20 °C and stored until analysis. Prior to analysis, filters were acid-fumed (37% HCl for 24 h) in order to remove inorganic carbon and dried at 40°C for 24 h. Subsequently, filters were wrapped in tin cups (8×8×15 mm), combusted and analyzed according to Sharp (1974) using an elemental analyzer (Euro EA). We determined high-molecular-weight (>1 kDa) particulate combined carbohydrates (pCCHO) based on Engel and Händel (2011) and particulate hydrolysable amino acids (pHAA) based on Lindroth and Mopper (1979) and Dittmar et al., (2009). The analysis of pCCHO detected 11 monomers: and the pHAA analysis classified 13 monomers. The calculations for the carbon and nitrogen contents of pCCHO and pHAA were based on carbon and nitrogen atoms contained in the identified monomers.本研究借助海洋雪采集器（Marine Snow Catcher, MSC）采集原位海洋雪聚集体。该设备可针对完整的原位形成聚集体，开展悬浮与快速沉降有机质的组成研究（Riley等，2012）。设备部署完成后，将其垂直放置于甲板上3小时，从MSC顶部收集含悬浮有机质的海水，并手动从MSC基座拾取快速沉降有机质。本次MSC部署于氧最低区（约400米水深）的混合层深度范围内。将颗粒有机碳（particulate organic carbon, POC）与颗粒有机氮（organic nitrogen, PON）的平行样，在低压（<200毫巴）条件下，过滤至预灼烧（450℃下灼烧5小时）的沃特曼GF/F滤膜（25 mm，0.7 µm）上。随后将滤膜置于-20℃冷冻保存，直至后续分析。分析前，将滤膜进行酸熏蒸（37% HCl熏蒸24小时）以去除无机碳，随后于40℃下干燥24小时。之后将滤膜包裹于8×8×15 mm的锡杯中，参照Sharp（1974）的方法，使用元素分析仪（Euro EA）进行灼烧与分析。本研究基于Engel与Händel（2011）的方法测定了高分子量（>1 kDa）颗粒结合态碳水化合物（particulate combined carbohydrates, pCCHO），并基于Lindroth与Mopper（1979）及Dittmar等（2009）的方法测定了颗粒水解氨基酸（particulate hydrolysable amino acids, pHAA）。其中，pCCHO分析共检出11种单体，pHAA分析则鉴定出13种单体。颗粒结合态碳水化合物与颗粒水解氨基酸的碳、氮含量计算，基于所鉴定单体中含有的碳、氮原子进行。