Calcium carbonate dissolution experiment Phase 2: Effect of elevated pCO2 and NO3- on sediment dissolution.

<p>Effect of elevated pCO2 and NO3- on sediment dissolution. Data are results of Phase 2&nbsp;of the sediment dissolution experiment described in:</p>

<p>Lantz, C. A., Carpenter, R. C. and Edmunds, P. J.: Calcium carbonate (CaCO3) sediment dissolution under elevated concentrations of carbon dioxide (CO2) and nitrate (NO3−). (2017) J. Exp. Mar. Bio. Ecol., 495,&nbsp;May, 48–56. doi:&nbsp;<a href=\"http://doi.org/10.1016/j.jembe.2017.05.014\">http://doi.org/10.1016/j.jembe.2017.05.014</a></p>

<p>The alkalinity anomaly technique was employed to measure changes in seawater total alkalinity inside of stirred benthic chambers.&nbsp;Water samples (75 mL) were taken at the beginning and end of each incubation from 0.6 cm diameter polyvinyl chloride in-line tubes connected to the side of the chamber, and these were used to measure seawater temperature, salinity, pH, and total alkalinity (TA). Temperature was recorded with a thermometer (± 0.05&nbsp;^oC; ThermoFisher Traceable^®) and salinity was measured with a bench-top conductivity meter (± 0.1 psu, YSI^®&nbsp;3100). TA and pH were measured within one hour of sample collection. Seawater collected for TA was filtered (0.45 µm; Chanson and Millero, 2007) and analyzed using potentiometric titrations with 0.1-N HCl using an automatic titrator (Mettler Toledo T50) (Dickson et al., 2007). Seawater pH was measured as mV and temperature with a potentiometric electrode (Orion ROSS pH/ATC Triode) and converted to the total scale (pH_T) using a calibration relationship prepared using Tris-buffers (Nemzer and Dickson, 2005).</p>

<p>See the publication for a detailed overview of the methodology.</p>

升高的二氧化碳分压（pCO₂）与硝酸根（NO₃⁻）对沉积物溶解过程的影响。本数据集对应下述文献中记载的沉积物溶解实验第二阶段的研究结果：

Lantz, C. A.、Carpenter, R. C. 与 Edmunds, P. J.：《二氧化碳（CO₂）与硝酸根（NO₃⁻）浓度升高条件下的碳酸钙（CaCO₃）沉积物溶解》（2017年），《实验海洋生物学与生态学杂志》，第495卷，5月刊，第48-56页。DOI：<a href="http://doi.org/10.1016/j.jembe.2017.05.014">http://doi.org/10.1016/j.jembe.2017.05.014</a>

本研究采用碱度异常法（Alkalinity Anomaly Technique）测定搅拌式底栖舱内海水总碱度（Total Alkalinity, TA）的变化。在每一轮培养的起始与结束阶段，通过连接于舱体侧壁、直径0.6 cm的聚氯乙烯（Polyvinyl Chloride, PVC）在线采样管采集75 mL水样，用于测定海水温度、盐度、pH值与总碱度（TA）。水温采用精度±0.05 ℃的温度计（ThermoFisher Traceable®）记录，盐度通过台式电导仪（YSI® 3100，精度±0.1 psu）测定。总碱度与pH值的测定需在水样采集后1小时内完成。用于总碱度测定的海水样品经0.45 µm滤膜过滤（参照Chanson与Millero, 2007的方法），并采用自动滴定仪（Mettler Toledo T50）以0.1当量浓度盐酸实施电位滴定分析（参照Dickson等人, 2007的方法）。海水pH值通过电位电极（Orion ROSS pH/ATC Triode）同步测定毫伏（mV）值与温度，并采用三（羟甲基）氨基甲烷（Tris）缓冲液制备的校准曲线转换为总尺度pH值（pH_T，参照Nemzer与Dickson, 2005的方法）。

具体实验方法的详细概述请参阅上述发表文献。