Use of gel probes for the determination of high resolution solute distributions in marine and estuarine pore waters

详细信息	查看全文 | 推荐本文 |

• 作者：Mortimer ; R.J.G. ; Krom ; M.D. ; Hall ; P.O.J. ; Hulth ; S. ; Stå ; hl ; H.
• 关键词：high resolution ; pore water ; estuarine ; marine ; gel probe
• 刊名：Marine Chemistry
• 出版年：1998
• 期刊代码：50_03044203
• 类别：env
• 出版时间：December, 1998
• 卷：63
• 期：1-2
• 页码：119-129
• 文件大小：264 K

摘要

Pore water profiles were obtained at high resolution (millimeter scale) in marine sediments using a DET (diffusive equilibration in thin films) gel probe. A plastic probe which holds a 1–2 mm thick polyacrylamide gel covered by a 0.45 μm Millipore filter is inserted into the sediment. The gel was prehydrated in water of similar salinity to the in situ sampling conditions. Chloride and sulphate needed 24 and 48 h for complete front and back equilibration, respectively, while 6–8 h (front) and 4–6 h (back) were used for calcium and alkalinity. Ammonia-N and total CO₂ were back-equilibrated for 2 h. Probes were sectioned immediately after sampling, stored for up to 1–2 days (NH₄p>+p>, ∑CO₂) or for up to 1–2 weeks (Ca, alkalinity, Cl, SO₄, NO₃), before they were back-equilibrated into Milli-Q water or 0.7 M NaCl (calcium and alkalinity). The gel retains between 3–7%of the total sulphate. A simple procedure has been developed to correct for this incomplete recovery. Recovery tests using seawater and 50%seawater spiked to concentrations found in nearshore pore waters, showed recoveries of 101.4±0.5%(chloride), 101.4±0.7%(bromide), 100.3±0.2%(nitrate), 96.6±0.7%(sulphate), 99.7±0.8%(ammonia-N), 99.1±1.2%(∑CO₂), 96.9±0.8%(calcium) and 96.8±1.4%(alkalinity) (mean±standard error). Pore water profiles obtained simultaneously using gel probes and conventional techniques (box core-anoxic slicing followed by centrifugation) showed excellent comparability at cm resolution though features which required higher resolution which could only be seen in the gel profiles.