Low dissolved DMSP concentrations in seawater revealed by small-volume gravity filtration and dialysis sampling
Low dissolved DMSP concentrations in seawater revealed by small-volume gravity filtration and dialysis sampling
复制标题
DOI：
10.4319/lom.2006.4.80
复制
发表时间：
2006-04-01
影响因子：
2.7
通讯作者：
Slezak, D
中科院分区：
文献类型：
--
作者：
Kiene, RP;Slezak, D
使用海水测试了各种过滤和被动透析方案，以确定二甲磺酰基丙酸酯 (DMSPd) 的溶解浓度，DMSPd 是一种源自许多海洋浮游植物细胞质的化合物。常用的采样程序，例如在线过滤、注射器压力过滤和通过玻璃纤维过滤器对相对较大体积的样品（5-50 mL）进行重力过滤，会导致 DMSPd 从颗粒材料中释放，这一点可以通过过滤体积增加 DMSPd 浓度来证明。过滤结束时过滤器暴露在空气中会导致特别严重的 DMSPd 释放。即使在极地水域（-1.8 摄氏度），透析袋或 Slide-A-Lyzer 透析盒也能在 4 小时内与海水 DMSPd 达到平衡，并且在某些情况下似乎可以提供准确的 DMSPd 浓度。然而，透析过程中在实验室容器（例如玻璃罐）中孵育海水有时会导致 DMSPd 的人为释放。因此，我们采用了小体积重力滴滤（SVDF）程序，其基本要素是：（i）直接从初级样品容器（例如Niskin瓶）收集20至50mL海水到干燥的全塑料过滤塔中； (ii) 使用 47 毫米直径 Whatman GF/F 过滤器； (iii) 通过重力（静水）压力快速（< 3 分钟）过滤； (iv) 仅收集第一个 3.5 mL 滤液用于 DMSPd 分析； (v) 切勿将过滤后的浮游生物暴露在空气中。 SVDF 程序似乎产生与在海水柱中孵育的透析采样器相同的低 DMSPd 浓度。使用 SVDF 程序，发现在广泛的海水类型和颗粒 DMSP 浓度范围内，DMSPd < 2.8 nM。我们的研究中观察到的最大 DMSPd 浓度 (2.8 nM) 远低于报道的全球平均 DMSPd 浓度 16.9 nM，这增加了过去数据收集可能受到过滤伪影影响的可能性。
A variety of filtration and passive dialysis protocols were tested with seawater for determination of the dissolved concentrations of dimethylsulfoniopropionate ( DMSPd), a compound originating in the cytosol of many marine phytoplankton. Commonly used sampling procedures, such as in-line filtration, syringe pressure filtration, and gravity filtration of relatively large-volume samples ( 5-50 mL) through glass fiber filters, caused release of DMSPd from particulate material as evidenced by increasing DMSPd concentrations with volume filtered. Exposure of filters to air at the end of filtration caused particularly severe DMSPd release. Dialysis bags or Slide-A-Lyzer dialysis cassettes equilibrated with seawater DMSPd within 4 h, even in polar waters ( -1.8 degrees C), and appeared to give accurate DMSPd concentrations in some circumstances. However, incubation of seawater in laboratory containers ( e. g., glass jars) during dialysis sometimes caused artifactual release of DMSPd. We therefore adopted a small-volume gravity drip filtration ( SVDF) procedure, the essential elements of which were: ( i) collection of 20 to 50 mL seawater directly from the primary sample container ( e. g., Niskin bottle) into a dry, all-plastic filtration tower; ( ii) use of a 47-mm-diameter Whatman GF/F filter; ( iii) rapid (< 3 min) filtration by gravity ( hydrostatic) pressure; ( iv) collection of only the first 3.5 mL filtrate for DMSPd analysis; and ( v) never exposing the filtered plankton to air. The SVDF procedure appeared to yield the same low DMSPd concentrations as dialysis samplers incubated in the ocean water column. Using the SVDF procedure, DMSPd was found to be < 2.8 nM over a broad range of ocean water types and particulate DMSP concentrations. The maximum DMSPd concentration observed in our study ( 2.8 nM) was far lower than the reported worldwide average DMSPd concentration of 16.9 nM, raising the possibility that past data collections may have been influenced by filtration artifacts.