A high‐resolution pore water sampler for sandy sediments
A high‐resolution pore water sampler for sandy sediments
复制标题
砂质沉积物高分辨率孔隙水采样器
DOI：
10.4319/lo.2001.46.1.0203
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发表时间：
2001
影响因子：
4.5
通讯作者：
K. Mcglathery
中科院分区：
文献类型：
--
作者：
P. Berg;K. Mcglathery
在本文中，我们提出了一种收集粗粒至细粒砂质沉积物孔隙水样品的新技术。我们已经将该技术用于现场采样和从带回实验室的沉积物岩心中提取孔隙水，在这两种情况下，深度分辨率都达到了1厘米。关键装置是一根长而薄（约2毫米）的不锈钢管，其尖端是专门设计的过滤器。通过将管插入所需深度的沉积物中，并从连接到管的注射器中轻吸来收集孔隙水样品。样品通过注射器过滤器立即注射到小瓶中，并储存起来供以后分析。该技术与其他在沙质沉积物中常用的方法相比，有一些明显的优势。与溶析仪或吸析仪相比，它提供了具有更高深度分辨率的孔隙水样品，这通常需要准确估计沉积物-水界面的通量或沉积物中溶质的转化率。与透析细胞或窥视器相比，新技术提供的测量值真正代表了收集时间。这在研究非稳态系统时是至关重要的。此外，由于管的尺寸小，泥沙的扰动最小。这在植被沉积物中尤其重要，在这些沉积物中，部署较大的常规采样器可能会造成重大干扰。最后，样品提取比其他技术更省力，只需要一次现场访问，每个样品的采样时间通常小于1分钟。在使用染料示踪剂的实验室测试中，我们发现孔隙水从周围沉积物的各个方向均匀地吸引到管尖端。在这些结果的基础上，我们提供了选择适当的采样深度间隔作为样本大小的函数的指导方针。本文介绍了巴哈马群岛植被覆盖的粗粒碳酸盐沉积物中的PO432和弗吉尼亚州温带沿海泻湖中无植被覆盖的细粒沙子中的NH4+1的代表性孔隙水剖面数据。
In this paper, we present a new technique for collecting pore‐water samples in coarse‐to fine‐grained sandy sediments. We have used the technique both for in situ sampling and for pore‐water extraction from sediment cores brought back to the laboratory, in both cases with a depth resolution as fine as 1 cm. The key device is a long, thin (~2 mm) stainless steel tube with a specially designed tip that functions as a filter. Pore‐water samples are collected by inserting the tube into the sediment at the desired depth and applying a light suction from a syringe connected to the tube. The sample is injected immediately into a vial through a syringe filter and stored for later analysis. The technique has some clear advantages over other methods that are used commonly in sandy sediments. In comparison with lysimeters or sippers, it gives pore‐water samples with a much higher depth resolution, which often is needed to accurately estimate fluxes across the sediment‐water interface or transformation rates of solutes within the sediments. In comparison with dialysis cells or peepers, the new technique gives measurements that truly represent the time of collection. This can be crucial when non‐steady‐state systems are studied. Furthermore, disturbance of the sediment is minimal because of the small dimension of the tube. This is especially important in vegetated sediments, in which the deployment of larger conventional samplers is likely to cause significant disturbance. Finally, sample extraction is less laborious than other techniques, requiring only one site visit and typically <1 min of sampling time per sample. In laboratory tests using a dye tracer, we showed that pore water was drawn evenly toward the tube tip from all directions in the surrounding sediment. On the basis of these results, we provide guidelines for choosing the appropriate sampling depth intervals as a function of the sample size. Data from representative pore‐water profiles are presented for PO432 from vegetated coarse‐grained carbonate sediments in the Bahamas and NH4+1 from fine‐grained unvegetated sands in a temperate coastal lagoon in Virginia.