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西南三江(金沙江、澜沧江和怒江)流域化学风化过程

陶正华1,2,赵志琦1**,张东1,3,李晓东1,王宝利1,吴起鑫1,4,张伟1,5,刘丛强1   

  1. 1中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳 550081;  2中国科学院大学, 北京 100049;  3河南理工大学资源环境学院, 河南焦作 454000;  4贵州大学喀斯特环境与地质灾害防治教育部重点实验室, 贵阳 550025;  5贵州师范学院地理与旅游学院, 贵阳 550018)
  • 出版日期:2015-08-10 发布日期:2015-08-10

Chemical weathering in the Three Rivers (Jingshajiang, Lancangjiang, and Nujiang) Watershed, Southwest China.

TAO Zheng-hua1,2, ZHAO Zhi-qi1**, ZHANG Dong1,3, LI Xiao-dong1, WANG Bao-li1, WU Qi-xin1,4, ZHANG Wei1,5, LIU Cong-qiang1   

  1. (1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; 2 University of Chinese Academy of Sciences, Beijing 100049, China; 3School of Resource and Environment, Henan Polytechnic University, Jiaozuo 454000, Henan, China; 4Key Laboratory of Karst Environment and Geohazard Prevention, Ministry of Education, Guizhou University, Guiyang 550025, China; 5School of Geography and Tourism, Guizhou Normal College, Guiyang 550018, China)
  • Online:2015-08-10 Published:2015-08-10

摘要: 选择中国西南三江流域作为研究对象,结合水化学及溶解性无机碳碳同位素,借助正演模型,分析河水溶解性组分来源及混入比例,说明硫酸参与区域碳酸盐矿物风化过程及CO2净释放量。结果表明:(1)西南三江流域河水受复杂岩性控制,金沙江河水以Na-Ca-Cl-HCO3为主,与流域上游蒸发盐矿物溶解有关,澜沧江和怒江则以Ca-HCO3为主,显示碳酸盐和硅酸盐矿物溶解的影响;(2)蒸发盐矿物溶解是金沙江干流河水阳离子主要来源,其贡献均值为52%,对澜沧江和怒江河水贡献较小,平均值分别为11%和2%。碳酸盐矿物溶解是澜沧江和怒江干流河水阳离子主要来源,其贡献均值分别为70%和78%,对金沙江干流河水的贡献较小,平均为38%,但对金沙江支流河水的贡献较大,平均为74%。硅酸盐风化产物对金沙江、澜沧江和怒江干流的平均贡献分别为8%、16%和15%,对金沙江支流河水的贡献为15%;(3)金沙江、澜沧江和怒江流域硅酸盐矿物风化速率分别为1.39、3.27和4.27 t·km-2·a-1,CO2消耗速率分别为0.34×105、1.18×105和1.40×105 mol·km-2·a-1,碳酸盐矿物风化速率分别为16.93、33.13和33.54 t·km-2·a-1,CO2消耗速率分别为1.40×105、2.47×105和2.22×105 mol·km-2·a-1;(4)西南三江流域河水硫酸盐主要来源于硫化物矿物氧化,硫酸参与碳酸盐矿物风化净释放CO2量分别为0.73×105、3.01×105和4.27×105 mol·km-2·a-1,高于中国贵州地区,应当在研究区域碳循环以及全球气候变化过程中引起重视。

关键词: 新疆, 理化性质, 重金属, 土壤质量, 棉田

Abstract: The Three Rivers (Jinshajiang River, Lancangjiang River, and Nujiang River) region (TRR) in Southwest China was selected to study the characteristics of chemical weathering during river erosion. With the forward model, hydrochemical characters and dissolved inorganic carbon isotopes of river waters were used to interpret the sources and their corresponding contributions to dissolved components, and to confirm the participation of sulfuric acid in carbonate weathering and the net release of CO2. The results showed that: (1) Hydrochemical compositions of river water were controlled by complex lithology. The ions of NaCa-Cl-HCO3 were dominated in Jinshajiang River due to outcrop of evaporates in its upstream region, while Ca-HCO3 was dominated in Lancangjiang River and Nujiang River due to the existence of abundant carbonate and silicate minerals; (2) Sources and ratios of dissolved components in river waters in TRR were variable. The dissolution of evaporates might control the sources of ions in the main stream of Jinshajiang River with an average percentage of 52%, but was minor in Lancangjiang River and Nujiang River with an average percentage of 11% and 2%, respectively. On the contrary, the dissolution of carbonates controlled the sources of ions in the main stream of Lancangjiang River and Nujiang River with an average of 70% and 78%, respectively, and was minor in the main stream but considerable in major tributary drainage of Jinshajiang River with a corresponding average of 38% and 74%. In addition, the contribution ratios of silicates weathering to the main streams of Jinshajiang River, Lancangjiang River and Nujiang River were 8%, 16%, and 15% respectively; (3) The weathering rates of silicates in the catchments of Jinshajiang River, Lancangjiang River and Nujiang River were 1.14, 3.32 and 4.32 t·km-2·a-1, respectively, and the corresponding CO2 consumption rates were 0.35, 1.19 and 1.41×105 mol·km-2·a-1. By contrast, the weathering rates of carbonates in the three studied rivers were 17.41, 34.04 and
34.84 t·km-2·a-1 with the CO2 consumption rates of 1.46, 2.69 and 2.53×105 mol·km-2·a-1 respectively; (4) Sulfate in the TRR was mainly derived from sulfide oxidation which led to net release rates of CO2 as 0.87, 3.01 and 4.36×105 mol·km-2·a-1 in Jinshajiang River, Lancangjiang River and Nujiang River, respectively. These values were higher than those in Guizhou, China, so attention should be paid to the important role of sulfuric acid in rock weathering during the study of regional carbon cycle and global climate change.

Key words: soil quality, heavy metal, Xinjiang, cotton field., physicochemical property