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Control of carbon dioxide exchange fluxes by rainfall and biological carbon pump in karst river–lake systems
Science of the Total Environment ( IF 8.2 ) Pub Date : 2024-05-23 , DOI: 10.1016/j.scitotenv.2024.173486
Chaowei Lai 1 , Zaihua Liu 2 , Qingchun Yu 3 , Hailong Sun 2 , Fan Xia 4 , Xuejun He 4 , Zhen Ma 2 , Yongqiang Han 4 , Xing Liu 4 , Pengyun Hao 1 , Qian Bao 5 , Mingyu Shao 2 , Haibo He 2
Affiliation  

As an important component of inland water, the primary factors affecting the carbon cycle in karst river–lake systems require further investigation. In particular, the impacts of climatic factors and the biological carbon pump (BCP) on carbon dioxide (CO) exchange fluxes in karst rivers and lakes deserve considerable attention. Using quarterly sampling, field monitoring, and meteorological data collection, the spatiotemporal characteristics of CO exchange fluxes in Erhai Lake (a typical karst lake in Yunnan, SW China) and its inflow rivers were investigated and the primary influencing factors were analyzed. The average river CO exchange flux reached 346.80 mg m h, compared to −6.93 mg m h for the lake. The carbon cycle in rivers was strongly influenced by land use within the basin; cultivated and construction land were the main contributors to organic carbon (OC) in the river ( = 0.66, < 0.01) and the mineralization of OC was a major factor in CO oversaturation in most rivers ( = 0.76, p < 0.01). In addition, the BCP effect of aquatic plants and the high pH in karst river–lake systems enhance the ability of water body to absorb CO, resulting in undersaturated CO levels in the lake. Notably, under rainfall regulation, riverine OC and dissolved inorganic carbon (DIC) flux inputs controlled the level of CO exchange fluxes in the lake (r = 0.78, < 0.05; r = 0.97, < 0.01). We speculate that under future climate and human activity scenarios, the DIC and OC input from rivers may alleviate the CO limitation of BCP effects in karst eutrophication lakes, possibly enabling aquatic plants to convert more CO into OC for burial. The results of this research can help advance our understanding of CO emissions and absorption mechanisms in karst river–lake systems.

中文翻译:


降雨和生物碳泵对岩溶河湖系统二氧化碳交换通量的控制



作为内陆水体的重要组成部分,岩溶河湖系统碳循环的主要影响因素有待进一步研究。特别是气候因素和生物碳泵(BCP)对喀斯特河流湖泊二氧化碳(CO)交换通量的影响值得高度关注。采用季度采样、现场监测和气象资料采集等方法,对洱海及其入湖河流CO交换通量的时空特征进行了调查,并分析了主要影响因素。河流平均二氧化碳交换通量达到 346.80 mg mh,而湖泊的平均 CO 交换通量为 -6.93 mg mh。河流中的碳循环受到流域内土地利用的强烈影响;耕地和建设用地是河流有机碳 (OC) 的主要贡献者 (= 0.66, < 0.01),OC 矿化是大多数河流 CO 过饱和的主要因素 (= 0.76, p < 0.01)。此外,水生植物的BCP效应和喀斯特河湖系统的高pH值增强了水体吸收CO的能力,导致湖泊中CO水平不饱和。值得注意的是,在降雨调节下,河流OC和溶解无机碳(DIC)通量输入控制了湖泊中CO交换通量的水平(r = 0.78,< 0.05;r = 0.97,< 0.01)。我们推测,在未来的气候和人类活动情景下,来自河流的 DIC 和 OC 输入可能会缓解喀斯特富营养化湖泊中 BCP 效应对 CO 的限制,可能使水生植物能够将更多的 CO 转化为 OC 进行掩埋。这项研究的结果有助于加深我们对岩溶河湖系统二氧化碳排放和吸收机制的理解。
更新日期:2024-05-23
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