Monitoring operations at the seafloor above a storage complex area are required to demonstrate that offshore storage of CO₂ in the deep subsurface is safe and effective. Within the framework of the STEMM-CCS project, the Goldeneye area was identified as an offshore experimental site for CO₂ storage. In this work, the physico-chemical characteristics of the water column at the Goldeneye site were determined by an in-depth analysis of measurements collated from CTD casts, discrete water samples and seafloor landers. The results showed a clear tidal, seasonal and inter-annual variability in the measured parameters within the monitoring period (Oct 2017- May 2019). Variations in pH and pCO₂ over a single tidal cycle were in the order of ±0.008 and ±1.5 μatm, respectively. The temporal variability of water column carbonate chemistry parameters was further defined with the aim to provide a solid background for the discrimination from natural changes of potential impacts of CO₂ emissions at the potential storage site. Here, we demonstrated how the combination of new and existing methods and technologies could be used for an effective assessment of water column conditions at a potential offshore carbon storage site.

需要对存储复杂区域上方的海底进行监视操作，以证明深层地下CO _2的海上存储是安全有效的。在STEMM-CCS项目的框架内，黄金眼地区被确定为CO ₂封存的近海实验地点。在这项工作中，通过对CTD铸件，离散水样和海底着陆器的测量结果进行深入分析，确定了Goldeneye站点水柱的理化特性。结果显示，在监测期内（2017年10月至2019年5月），测得的参数存在明显的潮汐，季节和年际变化。pH和pCO _2的变化单个潮汐周期上的最大扰动分别为±0.008和±1.5μatm。进一步定义了水柱碳酸盐化学参数的时间变异性，目的是为从潜在的存储地点区分CO ₂排放的潜在影响的自然变化提供坚实的背景。在这里，我们演示了如何将新的和现有的方法与技术相结合，以有效地评估潜在的海上碳封存点的水柱状况。