Bottle data from a coastal peatland at the German Baltic Sea in 2021

Rewetting peatlands is an important measure to reduce greenhouse gas (GHG) emissions. However, after rewetting, the areas are highly heterogeneous in terms of GHG exchange, which depends on water level and source, vegetation, previous use, and duration of rewetting. These challenging conditions require new technologies that go beyond discrete sampling. Here we present data from two autonomous lander platforms deployed at the sediment-water interface (bottom lander) of a shallow coastal peatland (approx. 1 m water depth) that was rewetted by brackish water from the Baltic Sea, thus becoming part of the coastal water through a permanent connection. These landers were equipped with six commercially available state-of-the-art sensors, and temporal high-resolution measurements of physico-chemical variables, including partial pressures of carbon dioxide (CO2) and methane (CH4), were made. The resolution of the field data ranged from 10 seconds to 120 minutes and was obtained for partial pressure of CO2 (Contros HydroC-CO2) and CH4 (Contros HydroC-CH4), temperature, salinity, pressure (water depth), oxygen (O2) (CTD-O2 with SBE-37SMP-ODO), the concentrations of phosphate (SBE HydroCycle PO4), nitrate (SBE SUNA V2), chlorophyll a and the turbidity (both with SBE-FLNTUSB ECO) as stationary measurements at two different locations in close proximity. The CTD and oxygen measurements provide exact water depth data for the respective lander locations. In the other data sets (e.g., CO2 measurements) rounded data are inserted instead of the exact depth data, which is 0.6 m for lander_1 and 0.9 m for lander_2. SUNA raw data are provided for completeness. However, we found them of insufficient quality to estimate nitrate concentrations due to interferences and biofouling. The deployment and recovery of the landers, and thus the measurements, took place between 02 June 2021 and 09 August 2021, and the sensors were operated under permanent wired power supply and a centralized timestamp. The sensors were maintained and cleaned bi-weekly. Results show considerable temporal fluctuations expressed as multi-day, diurnal, and event-based variability, with spatial differences caused by biologically-dominated variables.泥炭地复湿是减少温室气体（GHG）排放的重要措施。然而，复湿后区域的温室气体交换具有高度异质性，这取决于水位与水源、植被、历史用途及复湿持续时间。这些复杂条件需要超越离散采样的新技术。本文呈现了两个自主底部着陆器平台（bottom lander）的采集数据，它们部署于浅水滨海泥炭地（水深约1米）的沉积物-水界面（sediment-water interface）；该泥炭地由波罗的海微咸水复湿，通过永久连通成为沿海水体的一部分。这些着陆器配备了六台商用先进传感器，对理化变量进行了时间高分辨率测量，包括二氧化碳（CO₂）和甲烷（CH₄）的分压。现场数据的分辨率范围为10秒至120分钟，涵盖以下参数的定点测量（在两个邻近的不同位置）：CO₂分压（Contros HydroC-CO₂）、CH₄分压（Contros HydroC-CH₄）、温度、盐度、压力（水深）、氧气（O₂，采用CTD-O₂与SBE-37SMP-ODO传感器）、磷酸盐浓度（SBE HydroCycle PO4）、硝酸盐浓度（SBE SUNA V2）、叶绿素a及浊度（二者均采用SBE-FLNTUSB ECO传感器）。CTD与氧气测量数据为各着陆器位置提供了精确的水深信息。在其他数据集（如CO₂测量数据）中，使用了四舍五入的水深数据而非精确值：着陆器1的水深为0.6米，着陆器2为0.9米。为保证完整性，本数据集提供了SUNA原始数据；但由于干扰与生物附着，其质量不足以用于估算硝酸盐浓度。着陆器的部署与回收（即测量周期）为2021年6月2日至2021年8月9日，传感器采用永久有线供电及集中时间戳。传感器每两周维护清洁一次。结果显示，理化变量存在显著的时间波动，表现为多日尺度、昼夜尺度及事件驱动的变异性；空间差异则由生物主导变量所致。