Cui Rong-Yang, Chen An-Qiang, Liu Gang-Cai, Chen Qing-Fei, Ye Yuan-Hang, Wang Chi, Zhang Dan
Agricultural Environment Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming 650201, China.
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Chinese Academy of Sciences, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610299, China.
Huan Jing Ke Xue. 2024 Aug 8;45(8):4589-4599. doi: 10.13227/j.hjkx.202308021.
Dissolved carbon in groundwater plays an important role in carbon cycling and ecological function maintenance, and its concentration level affects the migration and transformation of pollutants in groundwater. To understand the spatiotemporal variation characteristics of dissolved carbon and its driving factors in shallow groundwater around plateau lakes, variations in the concentrations of dissolved organic carbon （DOC）, inorganic carbon （DIC）, and total carbon （DTC） and their driving factors in shallow groundwater （ = 404） around eight plateau lakes were analyzed. The results indicated that the average values of （DOC）, （DIC）, and （DTC） in shallow groundwater around plateau lakes were 8.23, 49.01, and 57.84 mg·L, respectively, with the （DOC） in 79.0% of shallow groundwater samples exceeding 5 mg·L. There were no significant differences in the DOC, DIC, and DTC concentrations between rainy and dry seasons, whereas the change in dissolved carbon concentrations in shallow groundwater were strongly affected by the intensity of agricultural intensification and the depth of groundwater table； the DOC, DIC, and DTC concentrations in shallow groundwater from facility agricultural regions （SFAR）, cropland fallow agricultural regions （CFAR）, and intensive agricultural regions with deeper groundwater tables （DIAR） were significantly reduced by 25.8% - 56.6%, 14.0% - 32.9%, and 16.6% - 36.7%, respectively, compared with those in intensive agricultural regions with shallower groundwater tables （SIAR）. Additionally, the dissolved carbon concentrations in shallow groundwater from DIAR were significantly lower than those of SFAR and CFAR. RDA revealed that physicochemical factors in water and soil significantly explained the changes in the dissolved carbon concentrations. Moreover, the dissolved carbon concentrations in shallow groundwater around Yilong Lake were significantly higher than those of other lakes, whereas that of Chenghai Lake was significantly lower than that of other lakes. Our study highlights that agricultural intensification intensity and groundwater table depth jointly drove the variations in dissolved carbon concentrations in shallow groundwater around plateau lakes. The study results are expected to provide a scientific basis for understanding the carbon cycle in plateau lake areas with underground runoff flowing into lakes and evaluating the attenuation of pollutants by dissolved carbon in shallow groundwater.
地下水中的溶解碳在碳循环和生态功能维持中发挥着重要作用，其浓度水平影响着地下水中污染物的迁移和转化。为了解高原湖泊周边浅层地下水中溶解碳的时空变化特征及其驱动因素，分析了八个高原湖泊周边浅层地下水（(n = 404)）中溶解有机碳（DOC）、无机碳（DIC）和总碳（DTC）浓度的变化及其驱动因素。结果表明，高原湖泊周边浅层地下水中DOC、DIC和DTC的平均值分别为8.23、49.01和57.84 mg·L，79.0%的浅层地下水样品中DOC超过5 mg·L。雨季和旱季DOC、DIC和DTC浓度无显著差异，而浅层地下水中溶解碳浓度的变化受农业集约化强度和地下水位深度的强烈影响；设施农业区（SFAR）、农田休耕农业区（CFAR）和地下水位较深的集约化农业区（DIAR）浅层地下水中的DOC、DIC和DTC浓度分别比地下水位较浅的集约化农业区（SIAR）显著降低25.8% - 56.6%、14.0% - 32.9%和16.6% - 36.7%。此外，DIAR浅层地下水中的溶解碳浓度显著低于SFAR和CFAR。冗余分析（RDA）表明，水和土壤中的理化因素显著解释了溶解碳浓度的变化。此外，异龙湖周边浅层地下水中的溶解碳浓度显著高于其他湖泊，而程海湖的溶解碳浓度显著低于其他湖泊。我们的研究强调，农业集约化强度和地下水位深度共同驱动了高原湖泊周边浅层地下水中溶解碳浓度的变化。研究结果有望为理解有地下径流流入湖泊的高原湖区的碳循环以及评估浅层地下水中溶解碳对污染物的衰减作用提供科学依据。
