我国典型陆地生态系统水化学离子特征及空间分布

选择中国生态系统研究网络(CERN)和国家生态系统观测研究网络(CNERN)中的33个陆地生态站水化学监测数据,分析了2010～2015年我国典型陆地生态系统地下水、静止地表水和流动地表水水化学离子特征及空间分布.结果表明,水中主要阴离子质量浓度为:HCO_3~- SO_4~(2-) Cl~- CO_3~(2-),以HCO_3~-和SO_4~(2-)为主,在地下水、静止地表水、流动地表水中HCO_3~-和SO_4~(2-)之和分别约占阴离子总量的71. 7%、75. 3%和74. 9%;阳离子以Ca2+和Na+为主,两者之和分别约占阳离子总量的69. 7%、64. 8%和68. 9%.不同生态区域水体离子浓度和离子比例差异较大,水化学类型有地带性差异,即西北干旱半干旱区、东部黄淮海平原区生态系统地下水水化学类型以Na-Mg-SO4-Cl型为主,且水体矿化度较高;亚热带红壤丘陵区地下水水化学类型以Ca-SO_4-HCO_3型为主,地表水以Ca-HCO_3-SO_4型为主;南亚热带丘陵赤红壤区地下水水化学类型以NaCa-HCO_3-Cl型为主;其它生态系统水化学类型以Ca-HCO_3型和Ca-Mg-HCO_3为主.地下水、静止地表水和流动地表水的水化学类型年际间无明显变化.

Ion Concentrations and Their Spatial Variability in Underground Water and Surface Water in Typical Terrestrial Ecosystems in China

The water chemistry data monitored during 2010-2015 by 33 terrestrial ecological stations from the Chinese Ecosystem Research Network (CERN) and the National Ecosystem Research Network of China (CNERN) were used to characterize ion concentrations and their spatial variability in underground water, still surface water, and flowing surface water from typical terrestrial ecosystems. The results showed the presence of mass-based concentrations of major anions, including HCO₃^- > SO₄^2- > Cl^- > CO₃^2-. Among them, HCO₃^- and SO₄^2- were dominant, and their sums accounted for 71.7%, 75.3%, and 74.9% of the total anions in underground water, still surface water, and flowing surface water, respectively. Cations were mainly Ca²⁺ and Na⁺, and their sums accounted for 69.7%, 64.8%, and 68.9% of the total cations in underground water, still surface water, and flowing surface water, respectively. The ion concentration and ion ratio in the underground water, still surface water, and flowing surface water differed largely among the studied regions. The hydrochemical type varied regionally, e.g., Na-Mg-SO₄-Cl type, usually with high content of salinity, was found in the underground water of ecological systems in the Northwest arid and semiarid areas and in the East Huanghuaihai Plain; Ca-SO₄-HCO₃ type in underground water and Ca-HCO₃-SO₄ type in surface water were found in hilly areas with subtropical red soil; Na-Ca-HCO₃-Cl type was present in underground water of south hilly areas with subtropical latosolic red soil; and Ca-HCO₃ and Ca-Mg-HCO₃ types were found in other ecological systems. Hydrochemical types had low inter-annual variation for both underground water and surface water.