地下水对干旱-半干旱区小型闭流湖泊碳平衡的影响机制  

Mechanism of Groundwater Impacting on Carbon Cycling in Small Closed Lakes in Arid and Semi–arid Areas

作　　者：李璐 燕亚平 史晓珑 董少刚 王平顺 韩学敏 LI Lu;YAN Yaping;SHI Xiaolong;DONG Shaogang;WANG Pingshun;HAN Xuemin(School of Ecology and Environment,Inner Mongolia University,Hohhot 010021,China;Inner Mongolia Ecological Environment Scientific Research Institute Limited,Hohhot 010015,China;Inner Mongolia Autonomous Region Environmental Monitoring Station Hohhot Sub-station,Hohhot 010030,China)

机构地区：[1]内蒙古大学生态与环境学院,呼和浩特010021 [2]内蒙古生态环境科学研究院有限公司,呼和浩特010015 [3]内蒙古自治区环境监测总站呼和浩特分站,呼和浩特010030

出　　处：《地球与环境》2025年第1期89-98,共10页Earth and Environment

基　　金：内蒙古自治区高等学校科学技术研究项目(NJZZ23089);国家自然科学基金项目(42267025)。

摘　　要：干旱–半干旱地区广泛分布的小型闭流湖泊主要依赖地下水的补给,在两者混合界面上发生的水化学作用会导致碳的迁移转化。然而,目前关于干旱–半干旱区小型闭流湖泊在接受地下水补给过程中发生的碳的迁移转化机制研究鲜有报道。本文以呼伦贝尔草原的柴达木诺尔湖为例,应用质量守恒原理、水文地球化学模拟构建地下水–湖泊混合区碳平衡方程,分析地下水补给湖泊过程中碳的分流机制。结果表明,地下水向湖泊的补给导致湖水中溶解的碳酸盐类(CO_(3)^(2–)、NaCO_(3)^(–)、MgCO_(3))向碳酸氢盐(HCO_(3)^(–)、NaHCO_(3)、MgHCO_(3)+)转化,这使两种水体混合过程具有显著的碳汇效应。地下水向柴达木诺尔湖输入的DIC总量为52.5 t/a,而由于地下水–湖水接触界面上发生的水化学反应,以CaCO_(3)沉淀从水体中去除的DIC量为2.2 t/a;两种水体混合过程中由方解石沉淀产生的CO_(2)会全部溶解于混合液中,同时还能以CO_(2)形态从大气吸收51.2 t/a[46.6 g/(m^(2)·a)]的碳。通过地下水的补给,柴达木诺尔湖DIC净增加量为101.5 t/a[92.3 g/(m^(2)·a)]。地下水与碱性湖泊的混合过程具有可观的固碳能力,是陆地生态系统重要的碳汇。Small closed lakes,prevalent in arid-semi and arid regions,strongly rely on groundwater replenishment.Hydrochemical interactions at their interface induce carbon migration and transformation.However,little research addresses the mechanism behind carbon dynamics in these lakes during groundwater replenishment.This study,exemplified by Chaidamu Nor Lake in the Hulunbuir Grassland,employed mass conservation and hydrogeochemical simulation to model the carbon balance in the groundwater-lake mixing zone.The results reveal that groundwater recharge prompts the conversion of dissolved carbonates(CO_(3)^(2–),NaCO_(3)^(–),MgCO_(3))in lake water to bicarbonates(HCO_(3)^(–),NaHCO_(3)^(–),MgHCO_(3)+),accentuating carbon sink effects during mixing.Groundwater input introduces 52.5 t/a of dissolved inorganic carbon(DIC)into Chaidamu Nor Lake,with 2.2 t/a of DIC removed via CaCO_(3)precipitation at the groundwater-lake interface.Calcite precipitation during mixing dissolves CO_(2)into the solution and absorbs 51.2 t/a[46.6 g/(m^(2)·a)]of atmospheric carbon.Groundwater recharge leads to a net DIC increase of 101.5 t/a[92.3 g/(m^(2)·a)]in Chaidamu Nor Lake.The mixing of groundwater and alkaline lakes exhibits significant carbon sequestration capacity and proves to be a significant carbon sink in terrestrial ecosystems.

关 键 词：地下水 碳平衡 地下水–湖泊系统 溶解无机碳(DIC) 混合作用 

分 类 号：X523[环境科学与工程—环境工程]