2017 SCOPE Particle Enrichment Rates

2017 SCOPE Particle Enrichment Rates Samples were collected during the HOT 286, HOT 291, HOT 292, and KOK 1703 cruises in the North Pacific Ocean. Rates of heterotrophic bacterial production were estimated based on the incorporation of 3H-leucine into protein. These rate measurements were conducted on experiments where whole seawater was amended with sinking particles. Particles were collected using a large diameter (1 m), surface-tethered, 50 μm nylon mesh net trap. The net trap was hung at 175 m for 24 h. Collected particles were concentrated in the net's cod-end and subsampled using a Folsom plankton splitter; these sample splits were subsequently screened through a 335-μm mesh to remove large zooplankton. The screened splits were then further divided into ten 100 mL aliquots using a McLane Wet Sample Divider and triplicate splits were pooled. 300 mL of the pooled splits were added to triplicate 10-liter carboys containing seawater collected from the same depth as the net trap deployment (175 m). Unamended seawater controls (no particle amendments) consisted of triplicate 10-liter carboys filled with seawater collected from 175 m from the same cast as the seawater used for the particle-amended treatments. Rates of bacterial production from the particle-amended experiments were estimated based on the incorporation of 3H-leucine into protein into filter size fractionated plankton samples. From each carboy (triplicate particle-amended and triplicate controls), six individual 40 mL polycarbonate centrifuge tubes were filled and amended with 20 nM 3H-leucine. Three of these 40 mL incubation tubes from each carboy served as time zero blanks and were immediately parallel filtered onto 25 mm diameter polycarbonate filters of varying pore sizes (0.2 μm, 2 μm, and 20 μm, respectively) and subsequently processed as described below. The remaining triplicate samples from each carboy were incubated in the dark at in situ temperatures for 4 h. Incubations were terminated by parallel filtration (one 40 mL tube per filter per carboy) onto the same filter pore sizes used for the time zero blanks. Filters were rinsed three times with 5 mL of cold 5% trichloroacetic acid, followed by three rinses (5 mL each) with cold 80% ethanol. Filters were removed from the vacuum filtration manifold and stored frozen in glass scintillation vials. In the shore-based laboratory, 10 mL of scintillation cocktail was added to each scintillation vial containing the filters and radioactivity on each filter was measured by liquid scintillation counting. Dark C-fixation was estimated based on 14C-bicarbonate assimilation into filter size fractionated plankton biomass. Each of the particle-amended and control carboys were subsampled into six 40 mL polycarbonate centrifuge tubes which were amended with 14C-bicarbonate. Three tubes from each carboy were parallel filtered onto 0.2 μm, 2 μm, and 20 μm, respectively. These samples served as time zero blanks. The remaining triplicate tubes were incubated for 24 h at in situ temperatures in the dark. At the end of the incubation period, a 25 μL subsample of the 14C-amended seawater was removed from each tube and added to a 20 mL scintillation vial containing 500 μL ß-phenylethylamine; these samples enabled quantification of the total amount of radioactivity added to each sample. The remaining sample volume was immediately parallel filtered onto the same filter types previously described (one tube per filter per carboy). Filters were removed from the filtration manifold and stored frozen in 20 mL glass scintillation vials, acidified with 1 mL of 2 mol L−1 hydrochloric acid and allowed to vent, uncapped, for 24 h in a fume hood. After acidification, 10 mL of scintillation cocktail was added and radioactivity was quantified by liquid scintillation counting. Rates of dark C-fixation were calculated, following subtraction of the time zero blanks, using HOT program measurements of dissolved inorganic C concentrations at 175 m in March and April of 2017 (2060 μmol C L−1). The timestamp is in UTC.2017年SCOPE颗粒富集速率数据集 样本采集于北太平洋的HOT 286、HOT 291、HOT 292及KOK 1703航次。异养细菌生产力速率通过3H-亮氨酸（3H-leucine）掺入蛋白质的量进行估算，该速率测定基于添加沉降颗粒的天然海水培养实验开展。 颗粒采集采用直径1 m、表面锚定的50 μm尼龙网捕集器，将其悬挂于175 m水深处静置24小时。采集的颗粒富集于网具囊端，通过Folsom浮游生物分样器进行分样；分样后经335 μm网筛过滤以去除大型浮游动物。经筛滤后的分样再通过McLane湿式样品分样器分为10份100 mL的子样本，随后将3份平行子样本混合。取300 mL混合后的子样本，加入至3组平行的10升大培养瓶中，瓶内装有与网捕集器部署水深相同（175 m）的海水。无颗粒添加的海水对照组由3组平行的10升大培养瓶组成，瓶内海水采集自与颗粒添加处理组相同站位的175 m水深。 颗粒添加实验组的细菌生产力速率，通过测定3H-亮氨酸掺入经滤膜孔径分级的浮游生物样本蛋白质中的量来估算。从每个培养瓶（3组颗粒添加组及3组对照组）中取6份40 mL聚碳酸酯离心管样本，添加终浓度为20 nM的3H-亮氨酸。每个培养瓶的6份样本中，3份作为零时刻空白组，立即并行过滤至直径25 mm、孔径分别为0.2 μm、2 μm和20 μm的聚碳酸酯滤膜上，随后按照下述步骤处理。剩余的3份平行样本置于原位温度的黑暗环境中培养4小时。培养结束后，通过并行过滤（每个培养瓶对应每种孔径的滤膜各1支40 mL离心管样本）终止培养，过滤所用滤膜孔径与零时刻空白组一致。滤膜先后用5 mL预冷的5%三氯乙酸漂洗3次，再用5 mL预冷的80%乙醇漂洗3次。将滤膜从真空过滤装置上取下，置于玻璃闪烁瓶中冷冻保存。 在岸基实验室中，向每个装有滤膜的闪烁瓶中加入10 mL闪烁液，通过液体闪烁计数法测定每张滤膜上的放射性活度。 暗碳固定速率通过14C-碳酸氢钠（14C-bicarbonate）掺入经滤膜孔径分级的浮游生物生物质中的量进行估算。每个颗粒添加组及对照组的大培养瓶均被分样为6份40 mL聚碳酸酯离心管样本，添加14C-碳酸氢钠。每个培养瓶的6份样本中，3份分别并行过滤至0.2 μm、2 μm和20 μm孔径的滤膜上，作为零时刻空白组。剩余的3份平行样本置于原位温度的黑暗环境中培养24小时。培养结束后，从每支离心管中取25 μL经14C标记的海水子样本，加入至装有500 μL β-苯乙胺的20 mL闪烁瓶中；该子样本用于定量测定每份样本添加的总放射性活度。剩余的样本体积立即并行过滤至前述规格的滤膜上（每个培养瓶对应每种滤膜各1支离心管样本）。将滤膜从过滤装置上取下，置于20 mL玻璃闪烁瓶中冷冻保存，随后加入1 mL 2 mol·L⁻¹盐酸酸化，并在通风橱中开盖敞放24小时以去除挥发性放射性物质。酸化完成后，加入10 mL闪烁液，通过液体闪烁计数法定量测定放射性活度。 暗碳固定速率通过扣除零时刻空白值后计算得到，计算时采用2017年3月及4月HOT项目测定的175 m水深溶解无机碳浓度（2060 μmol C·L⁻¹）。 时间戳采用协调世界时（UTC）。