Considerable carbon dioxide emissions from groundwater over-exploitation in the North China Plain

This study compiled hydrogeochemical data from 6202 groundwater sampling sites across the North China Plain (NCP), being sampled between 2007 and 2010. This dataset comprises 4454 points in shallow aquifer and 1748 points in deep aquifer, which were used for the analysis of the quantitative calculation of CO2 emissions induced by groundwater over-exploitation in the NCP. These datasets revealed elevated HCO3- concentrations in the groundwater within the study area. Coupled with severe local over-exploitation, these have resulted in CO2 emissions from groundwater depletion and groundwater extraction reaching 0.53 Tg/yr and 4.03 Tg/yr, respectively. These values accounted for around 9% and 39% of the total CO2 emissions from terrestrial waters in the NCP, far exceeding the average proportion of groundwater CO2 emissions to total terrestrial water CO2 emission in China (&lt;1%) and globally (∼1%). Additionally, shallow aquifers were found to emit significantly more CO2 than deep aquifers, contributing about 83% of the total emissions.本研究收集了2007至2010年间于华北平原（North China Plain, NCP）内6202个地下水采样点获取的水文地球化学数据。该数据集包含浅层含水层采样点4454个、深层含水层采样点1748个，用于华北平原地下水超采引发的二氧化碳（CO₂）排放量定量计算分析。本数据集揭示了研究区地下水中重碳酸根（HCO₃⁻）浓度偏高的特征；结合当地严重的地下水超采现状，地下水疏干与抽水作业分别产生了0.53 Tg/yr与4.03 Tg/yr的二氧化碳排放量，二者分别占华北平原陆地水域总二氧化碳排放量的约9%与39%，远高于中国（<1%）及全球（~1%）地下水二氧化碳排放量占陆地水域总排放量的平均比例。此外，研究发现浅层含水层的二氧化碳排放量显著高于深层含水层，贡献了总排放量的约83%。