王蕊, 刘兆飞, 姚治君
中国科学院地理科学与资源研究所,资源利用与环境修复重点实验室,北京 100101

Geochemistry of surface water and its major causality in northern-central Mongolia

WANGRui, LIUZhaofei, YAOZhijun
Key Lab for Resources Use & Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
通讯作者:通讯作者:姚治君（1959- ）,男,辽宁沈阳人,研究员,研究方向为流域水文与水资源。E-mail:yaozj@igsnrr.ac.cn
收稿日期:2016-10-22
修回日期:2017-01-23
网络出版日期:2017-04-20
版权声明:2017《地理研究》编辑部《地理研究》编辑部
基金资助:国家自然科学基金国际合作与交流项目（41561144012,41661144030）国家自然科学基金项目（41601021）
作者简介:
-->作者简介：王蕊（1987- ）,女,河北石家庄人,博士,助理研究员,研究方向为水文与水环境研究。E-mail:wangr@igsnrr.ac.cn



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摘要
资料匮乏区地表水化学特征调查是区域环境研究的基础,也是识别气候变化、地质构造等环境因素与径流过程相互作用的有效途径。基于2013年和2014年实测的离子化学数据,利用Gibbs相关分析及离子关系对比等经典地质化学分析方法,对蒙古中北部主要湖泊和河流离子化学特征及其主要控制因素进行分析。结果表明：该地区地表水体呈弱碱至碱性,河水中TDS平均值约为114.0 mg/L,并具有明显的空间差异。Ca²⁺和HCO₃^-普遍为该区地表水体中的优势离子;地表水体中离子主要来源于岩石风化过程,且以碳酸盐和硫酸盐矿物的风化作用最为强烈。该区目前地表水体水质呈良好状态,但硝酸盐呈一定的积累态势,因此人类活动对该区域水质的影响需要引起高度重视。

关键词：水化学特征;岩石风化;水质评价;蒙古
Abstract
Investigation of geochemistry of surface water is a fundamental study of the regional environment in ungauged areas. Also the study is helpful to determine the relationship between hydrological processes and environmental factors including the climate change and geologic structure. Sampling of the lake and river waters in the northern-central parts of Mongolia was carried out in 2013 and 2014. Then, using the measured chemical data of water solutes, the ion compositions and its controlling factors were analyzed preliminarily. The traditional methods in geochemistry, such as Gibbs correlation analysis and Stoichiometry, were applied in this study. Results indicate that the waters in the study area are from slightly alkaline to alkaline. The average value of total dissolved solids in river waters is about 114.0 mg/L, which presents a significantly different spatial variation of ion compositions in river waters. However, generally Ca²⁺ and HCO₃^- are the dominant ions in the surface waters in the study area. The most important source of the solutes in the surface waters is rock weathering process. In particular, the contribution of carbonate and sulfate minerals weathering are the largest. Although the current water quality is in a good situation in the northern-central parts of Mongolia, an accumulating trend of the nitrate in waters has been detected. Therefore, great attention should be paid to the influence from the anthropogenic input.

Keywords：hydrochemical characteristics;rock weathering;water quality assessment;Mongolia

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王蕊, 刘兆飞, 姚治君. 蒙古国中北部地表水离子化学特征及其主要成因[J]. , 2017, 36(4): 790-800 https://doi.org/10.11821/dlyj201704016
WANG Rui, LIU Zhaofei, YAO Zhijun. Geochemistry of surface water and its major causality in northern-central Mongolia[J]. 地理研究, 2017, 36(4): 790-800 https://doi.org/10.11821/dlyj201704016

1 引言

地表水体离子含量及化学组成受区域气候、地貌与地质条件及人类活动等众多因素影响^[1],能够反映区域气候和环境变化的综合特征。相对于气候与人为因子,区域基岩地球化学过程对地表水离子化学特征的影响更为重要^[2,3]。陈静生等指出流域岩石类型的不同组合是导致不同河流离子组成特征差异的主要因素^[4]。因此,开展区域地表水离子化学特征研究,对系统认识地表水体形成与运移机理,以及地表水体与周边地质等条件的相互作用关系具有重要的科学意义。
高原环境脆弱性较强,并较少受人类活动干扰,其地表水体离子化学特征更易反映气候及局地地质环境等自然条件的影响。目前,青藏高原的地表水化学研究开展较多,例如在羌塘自然保护区^[5]、玛旁雍错流域^[6]、雅鲁藏布江流域^[7]等地区,湖泊与河流的水化学特征及其与环境的相互作用已被关注。但是,对地处亚洲中部的蒙古高原的地表水化学研究工作较为薄弱。蒙古高原面积约260万km²,平均海拔约1500 m,包括蒙古国全部、俄罗斯南部和中国北部部分地区。目前该区水化学相关研究仅在中国境内有所开展,且多以黑河流域为主。刘蔚等系统分析了黑河流域水体化学特征及其演变规律^[8];郜银良等系统分析了黑河中游灌区水化学空间变异特征^[9];孟雪等从水循环的角度探讨了黑河中游地区水循环过程对土壤盐分特征的影响^[10]。对蒙古高原主体的蒙古国地表水化学的研究则仅限于伊凡诺夫在1956年对其河川水化学亲和力进行的初步分析^[11],通过91次采样对矿化度这一单一指标进行分析,指出河水矿化度的变化范围为30.1 mg/L（科布多河）~1592 mg/L（南曼科多—乌拉山脉北麓诸溪涧）。
本文以2013年8月和2014年8月两次野外实地调查样品数据为基础,揭示蒙古国中北部地区地表水体离子构成特征及空间差异,并利用Gibbs相关分析及离子关系对比方法,着重分析水体离子构成与周边地质条件的相互作用关系,初步探析水体中离子的可能来源。力争通过这些工作,丰富对蒙古国中北部地区的地表水化学特征的科学认识,推动资料稀缺的该区域地理、水资源相关研究。

2 研究方法与数据来源

2.1 研究区概况

蒙古国与中国内蒙古自治区相邻,面积约156万km²,位于亚洲大陆中部的蒙古高原,海拔介于530~4200 m,平均海拔约1490 m。蒙古西、西北和中部多为山地,东部为丘陵平原,南部是戈壁。境内主要河流为色楞格河及其支流鄂尔浑河,湖泊总面积约达1.5万km²,其中,位于北部的库苏古尔湖是蒙古最大的湖泊。蒙古国中北部地区主要包括中央、色楞格、达尔汗乌拉、鄂尔浑、布尔干、库苏古尔、后杭爱、前杭爱及巴彦洪戈尔等9省,以山地和高平原地貌为主（图1）。整个蒙古高原属温带大陆性气候,多年平均气温3.8 ℃,并由南向北递减。年平均降水量约200 mm,并受纬度影响,由南向北降水量逐渐增加^[12]。降水年内分配不均,约70%左右的降水发生在夏季,并主要集中在 7-8月;而冬季受西伯利亚—蒙古高压控制,降水量极少。
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图1研究区地理位置及采样点分布
-->Fig. 1Location of the study area and water sampling sites
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2.2 采样与分析方法

2013年8月5-14日与2014年8月11-20日先后对蒙古国中北部9个省的地表水体进行了较系统的调查,共采集水样51个,其中湖水水样13个,河流水样38个（图1）。样品均在10 cm深度左右采集,并储存于预先清洗过的50 ml聚乙烯采样瓶中。
野外调查中现场使用校准后的U-50多参数水质仪（HORIBA公司,日本）对各采样点位水温、pH、电导率（EC）、溶解氧（DO）、浊度（TURB）及总溶解固体含量（TDS）等11个参数进行测定。水样带回实验室后,放置冰箱进行低温保存,测试之前置于室内使其自然融化。主要离子含量在中国科学院地理科学与资源研究所水化学分析实验室进行分析测试。采用ICP光谱仪测量主要阳离子（K⁺、Na⁺、Ca²⁺、Mg²⁺）及SiO₂,采用LC-10ADvp离子色谱仪检测主要阴离子（SO₄^2-、Cl^-、NO₃^-）。测定前首先对测定程序进行空白校准,并在样品测定前后及测定中均实行质量控制,阳离子和阴离子测量精度分别可达到±2%和±5%。碱度由HCO₃^-代表,其含量通过离子电荷平衡法获得^[13,14]。
为明确研究区河流与湖泊水体离子化学特征,在统计分析基础上,应用水化学分析软件（AquaChem v3.70）绘制离子含量三角图;并结合经典Gibbs相关分析与统计分析方法,对水体中不同离子的相关关系进行评价,进一步探究地表水体离子可能来源。

3 结果分析

3.1 地表水化学性质

3.1.1 总体特征 蒙古中北部地表水体普遍呈弱碱至碱性,pH值的范围在7.3~9.2,均值为8.4。湖泊水体较清澈,在三个湖泊测点浊度平均约为7.4 NTU,最大值为20.5 NTU,出现在库苏古尔湖（L3）。河流水体受周边环境影响较湖泊更为剧烈,因此其浊度空间差异很大,38个测点的浊度在4.0~480 NTU范围内。水体矿化度可以通过电导率表示,该区除一个湖泊（L2）电导率高达37.9 ms/cm外,其他湖泊和河流电导率在39 μs/cm~829 μs/cm之间,平均为204 μs/cm,可见该区地表水体整体上矿化水平较低。
三个湖泊水体中TDS的平均值为65.3 mg/L（L1）、3624.8 mg/L（L2）和102.7 mg/L（L3）,因此L1和L3为典型的淡水湖,而L2为咸水湖,这可能与L2湖泊面积较小,长期的强烈蒸发作用导致盐分积累有关。河流水样中TDS的平均值为114.0 mg/L,但空间差异明显,从19.4 mg/L（R4）~490 mg/L（R13）不等。在海拔500~1500 m区域内,河水离子含量相对稳定,大部分水样中TDS值在100 mg/L~200 mg/L之间,平均值约为143.7 mg/L（图2）;但是,在乌兰巴托城市中部及边缘采集的河流样点（R1~R4）中TDS明显低于该海拔区间内的其他样点,TDS平均值仅为27.1 mg/L,这可能是水处理工程等人为干预的效果。海拔1500~2500 m区域内,河水中TDS的平均值约为85.4 mg/L,并随海拔的升高呈减少趋势,且二者反比例关系通过了α=0.05显著性水平的检验。可见地势对河流水化学的影响在高海拔地区反映的更为强烈。从空间分布看,海拔较低的北部地区河流中离子含量普遍高于地势稍高的中部地区,TDS平均值分别约为168.9 mg/L和133.4 mg/L;而中西部山地则因地势最高,河流中离子含量明显偏低,TDS的平均值约为63.0 mg/L（图3）。
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图2研究区河流水样中TDS与海拔的关系
-->Fig. 2Relationship between latitude and TDS in river water samples in the study area
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图3研究区河流水样中TDS空间分布（mg/L）
-->Fig. 3Spatial distribution of TDS in river water samples in the study area (mg/L)
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3.1.2 主要离子组成 在可直观表现出水体中各离子相对含量的三角图中,采集样品的绝大部分集中在钙离子和碳酸根离子端元附近（图4）,说明蒙古中北部地区地表水中Ca²⁺和HCO₃^-为最主要离子。
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图4研究区地表水样点在三角图上的分布
-->Fig. 4Ternary plots of cations and anions of the surface water samples in the study area
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两个淡水湖中,Ca²⁺作为优势阳离子,平均含量分别为20.6 mg/L（L1）和34.5 mg/L（L3）,占总阳离子含量的62.9%和68.4%。库苏古尔湖（L3）中Mg²⁺明显多于Na⁺和K⁺,三者平均含量分别为10.6 mg/L、3.8 mg/L和1.5 mg/L;而湖水L1中Mg²⁺与Na⁺含量相当,K⁺含量最少,三者分别为5.0 mg/L、5.6 mg/L和1.6 mg/L。HCO₃^-是淡水湖中含量最多的阴离子,平均为38.6 mg/L（L1）和78.7 mg/L（L3）,分别占总阴离子含量的74.4%和86.0%;相比而言,SO₄^2-和Cl^-含量较少,平均为9.9 mg/L（L1）、3.4 mg/L（L1）和11.1 mg/L（L3）、1.8 mg/L（L3）。咸水湖与淡水湖离子组成特征差异显著,L2中阳离子含量由大到小分别为Na⁺>Mg²⁺>K⁺>Ca²⁺,含量分别为1392 mg/L、227.8 mg/L、19.2 mg/L和4.8 mg/L,其中Na⁺占总阳离子含量的84.7%,优势明显;SO₄^2-成为优势阴离子,含量为1983 mg/L,占总阴离子含量的55.2%,Cl^-次之,HCO₃^-含量略少,二者分别为1064 mg/L和544.9 mg/L。
研究区大部分河水与淡水湖具有相似的离子组成特征（图4）,Ca²⁺和HCO₃^-作为最主要的阳离子和阴离子,平均含量分别为32.8 mg/L和75.4 mg/L（不包括R6、R29和R37）,占总阳、阴离子含量的59.2%和75.8%。在其余主要阳离子中,Na⁺含量略高于Mg²⁺,K⁺含量最低,三者平均分别约为11.9 mg/L、8.9 mg/L和1.8 mg/L。主要阴离子中,SO₄^2-含量高于Cl^-,二者平均分别约为19.7 mg/L和4.5 mg/L（不包括R6、R29和R37）。受局地地质环境等条件影响,R6和R37的阳离子组成特征表现为Na⁺>Ca²⁺>Mg²⁺>K⁺,而R29则表现为SO₄^2-含量极高,达到阴离子总量的82.5%左右（图4）。
不同区域河流的离子组成特征基本一致,但各离子相对含量具有一定差异（图5）。优势阳离子Ca²⁺在中东部河流中所占比例最高,约占阳离子总量的64.7%,在中部河流中比例相对较低,仅占52.0%左右。相反,中东部河流中Mg²⁺相对含量略低于其他区域,占阳离子总量的10.5%左右,而中部河流中Na⁺相对含量明显高于其他区域,达到阳离子总量的29.7%。河水中HCO₃^-的相对含量空间差异较小,北部地区略高（77.4%）,中西部地区略低（69.8%）;但SO₄^2-和Cl^-空间差异性相对HCO₃^-有所提高。其中SO₄^2-与Ca²⁺一致,而Cl^-与Na⁺空间分布相似,在中部地区河流中最高,占阴离子总含量的9.8%,而在中东部地区河流中比例最低,仅为2.9%左右。
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图5研究区河流水样中离子组成特征的空间差异
-->Fig. 5Spatial variation of ions in river water samples in the study area
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3.2 地表水体离子来源分析

地表水化学受地球物理、化学以及生物等众多过程影响。其中,河水中溶解性离子主要来源于海盐运移与大气沉降,碳酸盐、硅酸盐、蒸发盐的化学风化,以及人类活动输入^[15];而湖泊离子化学性质不仅受到入湖河流水质及周边地质环境的影响,同时受到湖水本身蒸发结晶作用的控制。Gibbs提出了一种基于TDS与Na⁺/(Na⁺+Ca²⁺)或TDS与Cl^-/(Cl^-+HCO₃^-)相关关系的简单方法,以判断三种控制地表水化学特征的自然因素的相对重要性,包括蒸发结晶作用、岩石风化和大气输入^[16]。其中,同时具有很高的TDS值（大于1000 mg/L）和较高的Na⁺/(Na⁺+Ca²⁺)或Cl^-/(Cl^-+HCO₃^-)比率（接近于1）的水体化学特征主要受到蒸发结晶作用的控制;而具有较低的TDS值（低于10 mg/L）和较高的离子比率（接近于1）的水体主要受到降水的影响;另外,对于具有中等TDS值（约70~300 mg/L）与较低离子比率（低于0.5）的水体,岩石风化作用是控制其离子化学特征的主导因素。
蒙古中北部地区大部分湖泊与河流样点在Gibbs图上主要分布于中部地区（TDS值在20 mg/L~490 mg/L范围内,阴阳离子比率均在0~0.5之间）（图6）,表明岩石风化是该区水化学特征的主控因素。L2湖泊样点位于右上角,即具有很高的TDS值和很高的Na⁺相对含量,表明其受到强烈的蒸发结晶作用。
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图6研究区地表水样点在Gibbs图上的分布
-->Fig. 6The Gibbs plot of the surface water samples in the study area
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3.2.1 海盐运移输入 地表水体中Cl^-最主要的来源为海盐运移,因此距海洋越远,Cl^-的含量越小^[17]。蒙古中北部是典型远离海洋的内陆区,区域内河流中Cl^-平均含量仅约为5.1 mg/L,且近80%的河水样点Cl^-含量小于5.0 mg/L,而在几条河流中Cl^-含量却明显增加,最高达到27.7 mg/L（图7）,由此表明河水中较高浓度Cl^-的主要贡献者应为流域内岩盐风化,而非海盐运移^[4,18]。
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图7研究区河流水样中Cl^-含量空间分布
-->Fig. 7Spatial distribution of Cl^- in river water samples in the study area
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3.2.2 人类活动输入 受气候环境及国家经济发展等条件制约,除乌兰巴托以外的蒙古中北部地区人口稀少,农业、工业等人类干扰较小,这点可从地表水体普遍较低的电导率及较小的离子组成空间差异表现出来^[18]。三个湖泊水样中NO₃^-的含量分别为5.3 mg/L、0 mg/L和1.5 mg/L。除R13水样中NO₃^-含量为46.7 mg/L以外,其余河流水样中NO₃^-含量均小于10 mg/L,且29个水样中NO₃^-含量均小于5 mg/L（图8）。此外,区域内所有样点Cl^-/Na⁺的摩尔比率均小于1.0,且空间异质性较小,也表明目前该区地表水化学受人类活动影响并不强烈^[18,19],各离子仍主要来源于岩石风化过程。
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图8研究区河流水样中NO₃^-含量空间分布
-->Fig. 8Spatial distribution of NO₃^- in river water samples in the study area
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3.2.3 岩石风化输入 自然条件下,流域中不同母岩（例如蒸发盐、碳酸盐和硅酸盐）的化学风化过程会给水体带来多种可溶解物质。一般来讲,K⁺和Na⁺主要来源于蒸发盐和硅酸盐风化,而Ca²⁺和Mg²⁺可能来源于蒸发盐、碳酸盐和硅酸盐风化;碳酸盐和硅酸盐风化还会带来HCO₃^-,而蒸发盐（包括硫酸盐矿物）风化则可能带来Cl^-和SO₄^2-[20]。
蒙古中北部地区河水中Na⁺/Cl^-的比率均远大于1.0（图 9a）,说明硅酸盐风化作用较蒸发盐更强烈。但由于Si与Na⁺、K⁺和HCO₃^-均未呈现显著的相关关系（图9b）,表明硅酸盐风化在该区域中也相对较弱。由于硅酸盐风化将会带来较多的Na⁺和K⁺,而带来较少的Ca²⁺和Mg^2+[21],因此河水中碱土元素（钙、镁）与碱金属元素（钠、钾）的比率平均约为4.5（图 9c）,表明含量较高的Ca²⁺和Mg²⁺是由相对更为强烈的碳酸盐风化作用带来的。河水中Ca²⁺与HCO₃^-呈良好的正相关关系,但Ca²⁺含量明显高于HCO₃^-,平均为HCO₃^-的1.9倍（图9d）,表明除碳酸盐风化外,Ca²⁺同时来源于其他岩石风化过程。大多数河流样点中（HCO₃^-+SO₄^2-）含量平衡了89.1%的Ca²⁺,部分河流样点二者含量之和与Ca²⁺已能够达到基本相当（图9e）,表明硫酸矿物风化作用对该区河流中离子具有一定贡献。同时,河流中Mg²⁺含量低于Ca²⁺（图 9f）,可以推断对河流离子产生较大贡献的硫酸盐矿物主要为石膏类（CaSO₄）。
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图9研究区不同离子摩尔质量浓度对比
-->Fig. 9Equivalent comparison between different ions in the study area
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3.3 地表水水质评价

根据世界卫生组织饮用水水质准则^[22],蒙古中北部地区河流水质各项指标均已达标,所有样点中主要离子含量远低于超标阈值,并且除R13外,其余样点水质均达到良好的标准（表1）。另外,将该区河流各离子均值情况与世界河流平均水平相对比,除K⁺和Cl^-含量较低以外,其他主要离子均高于世界河流平均水平。
Tab. 1
表1
表1研究区地表水离子含量与WHO饮用水水质标准（2006）对比
Tab. 1Range in values of geochemical variables in waters of the study area and WHO (2006)

指标	蒙古中北部地区河流			WHO饮用水水质标准（2006）		世界河流均值[15]
	R13	范围（除R13）		均值	良好	上限
pH	8.7	7.3~9.4	8.4	7.0~8.5	6.5~9.2
EC*	829	39~496	193.0	750	1500
TDS	490	19.4~268.3	103.8	600	1000
Na+	55.3	1.8~43.2	12.0	50	200	6.3
K+	11.1	0.6~11.6	1.8	100	250	2.3
Ca2+	111.3	6.3~71.8	30.4	75	250	15.0
Mg2+	40.5	0.9~30.9	8.1	30	150	4.1
HCO3-	336.2	2.2~251.9	67.4	300	600	58.4
SO42-	258.9	4.3~26.1	13.5	250	600	11.2
Cl-	25.8	0.3~27.7	4.6	250	600	7.8
NO3-	46.7	0~8.4	3.6	50	50	1.0

注：^*EC为电导率,单位为μs/cm;TDS及各离子指标单位均为mg/L。
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河流中NO₃^-含量过多,不仅会影响河流水质^[23],而且过多饮用后会在人体内被还原为NO₂^-;NO₂^-与人体血液作用,形成高铁血红蛋白,从而使血液失去携氧功能,导致缺氧中毒,威胁人类健康,严重时甚至可危及生命。研究区河流中NO₃^-含量虽然在饮用水标准范围内,但仅有3个样点含量在1.0 mg/L以下,低于世界平均水平。因此,对于主要由农耕等人类活动带来的硝酸盐积累问题在该区域需引起高度重视。

4 结论与讨论

对蒙古中北部地区地表水离子化学特征及其离子主要来源进行分析,丰富了对该区域水环境问题的科学认识,对水资源保护也具有重要的实践意义。结果表明：① 蒙古中北部地区地表水体呈弱碱至碱性,浊度普遍较低。河水中TDS平均值约为114.0 mg/L,但空间差异明显,北部离子含量相对较高,且水体离子含量随海拔升高呈一定的减少趋势。② Ca²⁺和HCO₃^-普遍为研究区地表水体中最主要的离子,含量均占阳、阴离子总量的一半以上。③ 由于蒙古高原远离海洋,并因恶劣的气候环境导致广阔的地域内人类活动相对较弱,使得海盐运移与人为输入对地表水体中离子的贡献十分有限,其离子主要来源于岩石风化。其中,碳酸盐和硫酸盐矿物的风化作用相对最为强烈,其次为硅酸盐,蒸发盐风化作用相对较弱。④ 目前,蒙古中北部地区地表水体水质呈良好状态,但多数离子的含量超过了世界河流平均水平,且硝酸盐呈现出一定的积累态势,因此人类活动对该区域水质的影响需要引起高度重视。
本研究利用实测样品对蒙古国中北部地区的地表水离子特征及其影响因素进行了初步探讨,由于收集的该区域观测资料有限,未能对离子来源、环境影响等问题做出定量结论,这将在未来工作中,随着降水、径流、地质等资料的逐步丰富,完成更为系统的探讨和解析。此外,蒙古高原作为亚洲中部一个完整的地域单元^[24],蒙古国与中国内蒙古地区的水化学对比研究也将成为今后工作的重点。
The authors have declared that no competing interests exist.

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[1]	Stallard R F, Edmond J M.Geochemistry of Amazon 2: The influence of geology and weathering environment on the dissolved load. Journal of Geophysical Research, 1983, 88(C14): 9671-9688.https://doi.org/10.1029/JC088iC14p09671URL [本文引用: 1]摘要 In the Amazon Basin, substrate lithology and erosional regime (seen in terms of transport-limited and weathering-limited denudation) exert the most fundamental control on the chemistry of surface waters within a catchment. Secondary effects, such as the precipitation of salts within soils and in stream beds, biological uptake and release, and cyclic salt inputs, are more difficult to discern. Samples can be separated into four principal groupings based on relationships between total cation charge (TZ+) and geology. (1) Rivers with 0<TZ+<200 eq/l drain the most intensely weathered materials (Upper Tertiary sediments, soils of the Negro Basin, and similarly weathered regions). These rivers show high levels of Fe, Al, H, and coloration and are enriched in Si relative to other major species; they exhibit cation ratios similar to those of substrate rocks. (2) Rivers with 200<TZ+<450 eq/l drain siliceous terrains. These rivers are also rich in silica relative to other species. Rivers draining weathering-limited siliceous terrains exhibit the highest TZ+ and their cation load is typically preferentially enriched in Na over K and Ca over Mg when compared to the rocks in their catchments. (3) Rivers with 450<TZ+<3000 eq/l drain marine sediments or red beds with high cation concentrations (resulting from the presence of carbonates and minor evaporites in the Peruvian Andes and reduced shales and minor carbonates in the Bolivian Andes). These rivers exhibit relatively high levels of Ca, Mg, alkalinity, and SO(in rivers draining reduced shales and minor evaporites). (4) Rivers with TZ+>3000 eq/l drain massive evaporites. These rivers are rich in Na and Cl. In the third and fourth categories, rivers tend to have 1:1 (equivalent) ratios of Na:Cl and (Ca+Mg):(alkalinity+SO), caused primarily by the weathering of carbonates and evaporites. Supplement available with entire article on microfiche. Order from the American Geophysical Union, 2000 Florida Avenue, N.W., Washington, DC 20009. Document C83-002; $2.50. Payment must accompany order.
[2]	王亚平, 王岚, 许春雪, 等. 长江水系水文地球化学特征及主要离子的化学成因 . 地质通报, 2010, 29(2-3): 446-456.https://doi.org/10.3969/j.issn.1671-2552.2010.02.032URL [本文引用: 1]摘要 在分析长江流域76个位点的水化学数据的基础上,运用吉布斯(Gibbs)图、三角图、主成分分析方法研究岩性对长江水表河水中离子化学特征的影响和流域的主要风化过程.结果表明,长江水系的主要离子化学特征受岩石风化作用的影响,其中碳酸盐和蒸发岩矿物对干流水系溶质的贡献率分别为43.6%和37.9%,而对支流水系溶质的贡献率分别为33.1%和39.1%.干流流域内主要的风化反应以白云石和方解石的溶解为主,而支流流域内C1~-/(Na~++K~+)接近1:1,体现出蒸发岩风化的显著特性.Si/K比值较低,表明长江流域内的风化反应是在表生环境中进行的,且产物是富含阳离子的次生矿物. [Wang Yaping, Wang Lan, Xu Chunxue, et al.Hydro-geochemistry and genesis of major ions in the Yangtze River, China. Geological Bulletin of China, 2010, 29(2-3): 446-456.]https://doi.org/10.3969/j.issn.1671-2552.2010.02.032URL [本文引用: 1]摘要 在分析长江流域76个位点的水化学数据的基础上,运用吉布斯(Gibbs)图、三角图、主成分分析方法研究岩性对长江水表河水中离子化学特征的影响和流域的主要风化过程.结果表明,长江水系的主要离子化学特征受岩石风化作用的影响,其中碳酸盐和蒸发岩矿物对干流水系溶质的贡献率分别为43.6%和37.9%,而对支流水系溶质的贡献率分别为33.1%和39.1%.干流流域内主要的风化反应以白云石和方解石的溶解为主,而支流流域内C1~-/(Na~++K~+)接近1:1,体现出蒸发岩风化的显著特性.Si/K比值较低,表明长江流域内的风化反应是在表生环境中进行的,且产物是富含阳离子的次生矿物.
[3]	黄奇波, 覃小群, 刘朋雨, 等. 乌江中上游段河水主要离子化学特征及控制因素 . 环境科学, 2016, 37(5): 1779-1787.https://doi.org/10.13227/j.hjkx.2016.05.023URL [本文引用: 1]摘要 开展人类活动影响下乌江中上游段河流水化学特征研究,有助于流域地表水资源有效开发利用和保护.本文采用主成分分析法对乌江中上游段的六冲河、三岔河、猫跳河、清水河的主要离子化学特征及控制因素进行了定量评价.结果表明,乌江上游段4条河流优势阳离子均为Ca~(2+)、Mg~(2+),两者占全部阳离子的70%以上,阴离子以HCO~-_3、SO~(2-)_4为主,两者占总阴离子的85%以上.与乌江1999年水化学数据相比,本次样品的阴阳离子浓度出现了明显增加,主要表现在NO~-_3、SO~(2-)_4等受人为活动影响显著的离子方面.受流域碳酸盐岩地层的控制,4条河流水化学类型以HCO_3~-Ca为主,少部分样点为HCO_3·SO_4-Ca型,反映出部分样点可能受到人类源的SO~(2-)_4影响.河水中Na~+、K~+、Cl~-主要来源于大气输入,Ca~(2+)、HCO~-_3、Mg~(2+)主要来源于碳酸盐岩的溶解;NO~-_3和SO~(2-)_4主要来源于人为活动.主成分分析法和相关分析得出:六冲河、三岔河、清水河上游水化学成分主要受大气降水及碳酸盐岩的溶解因子的控制,向下游受人为活动因子影响均增强;猫跳河上游、下游水化学组成主要受大气降水及碳酸盐岩的溶解控制,而中游湖泊受人为活动影响明显.清水河支流南明河中下游水化学组成主要受人为活动因子控制. [Huang Qibo, Qin Xiaoqun, Liu Pengyu, et al.Major ionic features and their controlling factors in the upper-middle reaches of Wujiang River. Environmental Science, 2016, 37(5): 1779-1787.]https://doi.org/10.13227/j.hjkx.2016.05.023URL [本文引用: 1]摘要 开展人类活动影响下乌江中上游段河流水化学特征研究,有助于流域地表水资源有效开发利用和保护.本文采用主成分分析法对乌江中上游段的六冲河、三岔河、猫跳河、清水河的主要离子化学特征及控制因素进行了定量评价.结果表明,乌江上游段4条河流优势阳离子均为Ca~(2+)、Mg~(2+),两者占全部阳离子的70%以上,阴离子以HCO~-_3、SO~(2-)_4为主,两者占总阴离子的85%以上.与乌江1999年水化学数据相比,本次样品的阴阳离子浓度出现了明显增加,主要表现在NO~-_3、SO~(2-)_4等受人为活动影响显著的离子方面.受流域碳酸盐岩地层的控制,4条河流水化学类型以HCO_3~-Ca为主,少部分样点为HCO_3·SO_4-Ca型,反映出部分样点可能受到人类源的SO~(2-)_4影响.河水中Na~+、K~+、Cl~-主要来源于大气输入,Ca~(2+)、HCO~-_3、Mg~(2+)主要来源于碳酸盐岩的溶解;NO~-_3和SO~(2-)_4主要来源于人为活动.主成分分析法和相关分析得出:六冲河、三岔河、清水河上游水化学成分主要受大气降水及碳酸盐岩的溶解因子的控制,向下游受人为活动因子影响均增强;猫跳河上游、下游水化学组成主要受大气降水及碳酸盐岩的溶解控制,而中游湖泊受人为活动影响明显.清水河支流南明河中下游水化学组成主要受人为活动因子控制.
[4]	Chen J, Wang F Y, Xia X H, et al.Major element chemistry of the Changjiang (Yangtze River). Chemical Geology, 2002, 187: 231-255.https://doi.org/10.1016/S0009-2541(02)00032-3URL [本文引用: 2]摘要 ABSTRACT The chemistry of major elements (Ca, Mg, Na, K, HCO3, SO4, Cl, and Si) in the river water of the Changjiang (Yangtze River) was studied, based on continuously monitored data at 191 stations in the drainage basin for the period 1958–1990. The results show that the total dissolved solid (TDS) concentration of the Changjiang varies over an order of magnitude throughout the basin (49.7–518.1 mg/l), with a medium TDS concentration of 205.9 mg/l, about three times the global average. In contrast, the TDS at a given main-channel station varies only slightly in different seasons with a variation factor less than 2.0, despite a substantial water dilution in the summer flood season. The major element chemistry of the Changjiang is mainly controlled by rock weathering, with the anion HCO3 and the cation Ca dominating the major ion composition, due to the abundance of carbonate rocks in the basin. A persistently increasing trend has been observed in the concentrations of SO4 and, to a lesser extent, Cl in the Changjiang, a signature of considerable anthropogenic impacts (e.g., acid deposition). Flux calculations at Datong (the most downstream main-channel station without tidal influence) indicate that the Changjiang transports ca. 154×106 tons/year of TDS to the sea, second only to the Amazon in the world.
[5]	Wang R, Liu Z F, Jiang L G, et al.Comparison of surface water chemistry and weathering effects of two lake basins in the Changtang Nature Reserve, China. Journal of Environmental Sciences, 2016, 41(3): 183-194.https://doi.org/10.1016/j.jes.2015.03.016URLPMID:26969064 [本文引用: 1]摘要 Abstract The geochemistry of natural waters in the Changtang Nature Reserve, northern Tibet, can help us understand the geology of catchments, and provide additional insight in surface processes that influence water chemistry such as rock weathering on the Qinghai–Tibet Plateau. However, severe natural conditions are responsible for a lack of scientific data for this area. This study represents the first investigation of the chemical composition of surface waters and weathering effects in two lake basins in the reserve (Lake Dogaicoring Qiangco and Lake Longwei Co). The results indicate that total dissolved solids (TDS) in the two lakes are significantly higher than in other gauged lakes on the Qinghai–Tibet Plateau, reaching 20–40 g/L, and that TDS of the tectonic lake (Lake Dogaicoring Qiangco) is significantly higher than that of the barrier lake (Lake Longwei Co). Na+ and Cl61 are the dominant ions in the lake waters as well as in the glacier-fed lake inflows, with chemical compositions mainly affected by halite weathering. In contrast, ion contents of inflowing rivers fed by nearby runoff are lower and concentrations of dominant ions are not significant. Evaporite, silicate, and carbonate weathering has relatively equal effects on these rivers. Due to their limited scope, small streams near the lakes are less affected by carbonate than by silicate weathering.
[6]	Yao Z J, Wang R, Liu Z F, et al.Spatial-temporal pattern of major ion chemistry and its controlling factors in the Manasarovar Basin, Tibet. Journal of Geographical Sciences, 2015, 25(6): 687-700.https://doi.org/10.1007/s11442-015-1196-5URLMagsci [本文引用: 1]摘要 The Manasarovar Basin in southern Tibet, which is considered a holy land in Buddhism, has drawn international academic attention because of its unique geographical environment. In this study, based on actual measurements of major ion concentrations in 43 water samples collected during the years 2005 and 2012, we analyzed systemically the spatialtemporal patterns of water chemistry and its controlling factors in the lake and inflowing rivers. The results reveal that the water in the Manasarovar Basin is slightly alkaline, with a p H ranging between 7.4 7.9. The amounts of total dissolved solids(TDS) in lake and river waters are approximately 325.4 and 88.7 mg/l, respectively, lower than that in most of the surface waters in the Tibetan Plateau. Because of the long-term effect of evaporative crystallization, in the lake, Na+ and HCO 3 have the highest concentrations, accounting for 46.8% and 86.8% of the total cation and anion content. However, in the inflowing rivers, the dominant ions are Ca2+ and HCO 3, accounting for 59.6% and 75.4% of the total cation and anion content. The water exchange is insufficient for such a large lake, resulting in a remarkable spatial variation of ion composition. There are several large inflowing rivers on the north side of the lake, in which the ion concentrations are significantly higher than that on the other side of the lake, with a TDS of 468.9 and 254.9 mg/l, respectively. Under the influence of complicated surroundings, the spatial variations in water chemistry are even more significant in the rivers, with upstreams exhibiting a higher ionic content. The molar ratio between(Ca2++Mg2+) and(Na++K+) is much higher than 1.0, revealing that the main source of ions in the waters is carbonate weathering. Although natural processes, such as rock weathering, are the major factors controlling main ion chemistry in the basin, in the future we need to pay more attention to the anthropogenic influence.
[7]	Jiang L G, Yao Z J, Wang R, et al.Hydrochemistry of the middle and upper reaches of the Yarlung Tsangpo River system: Weathering processes and CO2 consumption. Environmental Earth Sciences, 2015, 74(3): 2369-2379.https://doi.org/10.1007/s12665-015-4237-6URL [本文引用: 1]摘要 Abstract The study focuses on the chemical compositions of the river waters in the middle and upper reaches of the Yarlung Tsangpo river system. Samples were collected in two periods along the river system to analyze the spatio-temporal variation characteristics and to determine the weathering processes and CO 2 consumption. The results show that the chemical facies of river waters are dominated by Ca-HCO 3 type and the TDS values cover a wide range of 98.2 619.8 mg/l with an average value of 268.6 mg/l, which is higher than that of the global river waters. There are three major reservoirs (carbonates, evaporites, and silicates) contributing to the major ions, and the pre-dominances of the reservoirs of different rivers show spatial heterogeneity. The chemical weathering rates of silicates and carbonates are 3.43 and 4.49 t/km 2 /year, respectively. Overall, the middle and upper reaches of Yar-lung Tsangpo are responsible for 0.3 and 0.16 % of global atmospheric CO 2 consumption by silicates (1.7 9 10 5 mol/ km 2 /year) and carbonates (1.27 9 10 5 mol/km 2 /year), respectively. In addition, the chemical weathering fluxes of the catchments consume atmospheric CO 2 of 0.5456 Tg C/year, accounting for 0.14 % of the total organic carbon flux to the oceans by rivers globally.
[8]	刘蔚, 王涛, 高晓清, 等. 黑河流域水体化学特征及其演变规律 . 中国沙漠, 2004, 24(6): 755-762.https://doi.org/10.3321/j.issn:1000-694X.2004.06.017URLMagsci [本文引用: 1]摘要 通过对干旱地区内陆河流域黑河的降水、地表水、地下水样的水体进行化学分析,得出以下初步的结论:大气降水的共同特征是矿化度低,但离子含量和化学组成在流域上、中、下游不近相同;地表水体化学特征分异规律为高山冰雪寒冷带、高山草甸带、山地森林灌丛带、山地草原带、荒漠草原带;地下水体化学特征分异规律为山区裂隙水及山前砾石带重碳酸盐带,山前冲、洪积、湖积平原硫酸盐带,荒漠区及积盐洼地氯化物带。 [Liu Wei, Wang Tao, Gao Xiaoqing, et al.Distribution and evolution of water chemical characteristics in Heihe River Basin. Journal of Desert research, 2004, 24(6): 755-762.]https://doi.org/10.3321/j.issn:1000-694X.2004.06.017URLMagsci [本文引用: 1]摘要 通过对干旱地区内陆河流域黑河的降水、地表水、地下水样的水体进行化学分析,得出以下初步的结论:大气降水的共同特征是矿化度低,但离子含量和化学组成在流域上、中、下游不近相同;地表水体化学特征分异规律为高山冰雪寒冷带、高山草甸带、山地森林灌丛带、山地草原带、荒漠草原带;地下水体化学特征分异规律为山区裂隙水及山前砾石带重碳酸盐带,山前冲、洪积、湖积平原硫酸盐带,荒漠区及积盐洼地氯化物带。
[9]	郜银梁, 陈军锋, 张成才, 等. 黑河中游灌区水化学空间变异特征 . 干旱区地理, 2011, 34(4): 575-583.URL [本文引用: 1]摘要 黑河中游分布着大型农灌区,是 黑河流域人为干预作用最为强烈的区域。综合运用水化学数理统计和水化学类型分析方法,对灌区地表水与地下水的水化学特征进行系统分析,结果表明:(1)黑 河中游灌区地表水与地下水主要水化学类型从东南向西北都经过了由HCO3--SO42-型水向SO24--HCO3-型水,再向SO42--Cl-型水演 化的过程。主要支流山丹河与梨园河水化学特征不同,北山高矿化度水汇入,也部分影响着河流及地下水化学组成。(2)地表水与地下水主要离子沿流程都不断增 加,从而引起矿化度的增大。地下水矿化度最小值(小屯灌区292.2 mg/L)和最大值(宣化灌区3 448.3 mg/L)表明了不同的运移规律和补给来源。(3)SO42-、Na+是决定地下水盐化作用的主要变量,地下水在灌区运移的过程中,主要的水化学作用由溶 滤作用为主转变为蒸发浓缩作用为主。 [Gao Yinliang, Chen Junfeng, Zhang Chengcai, et al.Hydrochemical characteristics of the irrigation area in the middle reaches of the Heihe River Basin. Arid Area Geography, 2011, 34(4): 575-583.]URL [本文引用: 1]摘要 黑河中游分布着大型农灌区,是 黑河流域人为干预作用最为强烈的区域。综合运用水化学数理统计和水化学类型分析方法,对灌区地表水与地下水的水化学特征进行系统分析,结果表明:(1)黑 河中游灌区地表水与地下水主要水化学类型从东南向西北都经过了由HCO3--SO42-型水向SO24--HCO3-型水,再向SO42--Cl-型水演 化的过程。主要支流山丹河与梨园河水化学特征不同,北山高矿化度水汇入,也部分影响着河流及地下水化学组成。(2)地表水与地下水主要离子沿流程都不断增 加,从而引起矿化度的增大。地下水矿化度最小值(小屯灌区292.2 mg/L)和最大值(宣化灌区3 448.3 mg/L)表明了不同的运移规律和补给来源。(3)SO42-、Na+是决定地下水盐化作用的主要变量,地下水在灌区运移的过程中,主要的水化学作用由溶 滤作用为主转变为蒸发浓缩作用为主。
[10]	孟雪, 张娟, 郑一, 等. 黑河中游地区水循环过程对土壤盐分特征的影响 . 生态环境学报, 2015, 24(7): 1108-1112.https://doi.org/10.16258/j.cnki.1674-5906.2015.07.004URL [本文引用: 1]摘要 干旱、半干旱区的土壤盐渍化是重要的生态环境问题。黑河流域是我国第二大内陆河流域，研究该地区的土壤盐渍化问题对于我国西部地区的可持续发展具有重要意义。黑河的中游地区集中了流域内绝大部分人口和经济活动（以农业生产为主）。该研究对黑河中游地区表层土壤进行了全面采样，测定了土壤含盐量及其离子构成；并通过主成分分析确定了表征盐渍化程度的第一主成分和表征碱化程度的第二主成分。结合地表-地下水耦合模拟的结果，探讨了研究区水循环过程对土壤盐分特征的影响。研究结果表明，黑河中游表层土壤的盐渍化程度较高，高台-金塔一带盐渍化最严重，含盐量最高可达31.4%，其次为酒泉北部和张掖南部地区，含盐量在0.20%-0.37%之间。黑河中游土壤的盐渍化程度与地下水埋深密切相关。总体而言，地下水埋深越浅，土壤含盐量的均值越高，而标准差越大。研究区土壤主要呈原生盐渍化，次生盐渍化现象不显著。黑河中游土壤碱化程度较轻，碱化程度和盐渍化程度的空间分布呈反向关系。黑河中游的灌溉活动未造成显著的次生盐渍化，但一定程度上提高了土壤的碱化程度。与以往研究相比，该研究更全面地覆盖了黑河中游地区的代表性地点，并定量分析了区域水循环与土壤盐渍化之间的联系，研究结果对于我国西部地区水土资源的可持续开发利用具有重要参考价值。 [Meng Xue, Zhang Juan, Zheng Yi, et al.Impacts of hydrological processes on soil salinity in the middle Heihe River Basin. Ecology and Environmental Sciences, 2015, 24(7): 1108-1112.]https://doi.org/10.16258/j.cnki.1674-5906.2015.07.004URL [本文引用: 1]摘要 干旱、半干旱区的土壤盐渍化是重要的生态环境问题。黑河流域是我国第二大内陆河流域，研究该地区的土壤盐渍化问题对于我国西部地区的可持续发展具有重要意义。黑河的中游地区集中了流域内绝大部分人口和经济活动（以农业生产为主）。该研究对黑河中游地区表层土壤进行了全面采样，测定了土壤含盐量及其离子构成；并通过主成分分析确定了表征盐渍化程度的第一主成分和表征碱化程度的第二主成分。结合地表-地下水耦合模拟的结果，探讨了研究区水循环过程对土壤盐分特征的影响。研究结果表明，黑河中游表层土壤的盐渍化程度较高，高台-金塔一带盐渍化最严重，含盐量最高可达31.4%，其次为酒泉北部和张掖南部地区，含盐量在0.20%-0.37%之间。黑河中游土壤的盐渍化程度与地下水埋深密切相关。总体而言，地下水埋深越浅，土壤含盐量的均值越高，而标准差越大。研究区土壤主要呈原生盐渍化，次生盐渍化现象不显著。黑河中游土壤碱化程度较轻，碱化程度和盐渍化程度的空间分布呈反向关系。黑河中游的灌溉活动未造成显著的次生盐渍化，但一定程度上提高了土壤的碱化程度。与以往研究相比，该研究更全面地覆盖了黑河中游地区的代表性地点，并定量分析了区域水循环与土壤盐渍化之间的联系，研究结果对于我国西部地区水土资源的可持续开发利用具有重要参考价值。
[11]	伊凡诺夫A T. 蒙古人民共和国河川水的化学亲合力 . 地理译报, 1956, (4): 302.URL [本文引用: 1]摘要 正 按照河川的水量,蒙古人民共和国可划分为两个不相等的部分。河纲发达的区域,占全国面积三分之一(杭爱区),其余干旱的地区,几乎完全没有河川(戈壁 区)。作者根据91次的分析,绘制了蒙古人民共和国河川水矿化度草图。确定了河水矿化度的变化是自30.1毫克/公升(科布多河)至1592毫克/公升 (南曼科多-鸟拉山脈北麓诸溪涧)。河川水所含的矿化度一般都不很高。河川水的化学亲合力是垂直带状分布的,这种分 [Ivanov A T.Chemical affinity of river water in the People's Republic of Mongolia. Geographic Translated Newspaper, 1956, (4): 302.]URL [本文引用: 1]摘要 正 按照河川的水量,蒙古人民共和国可划分为两个不相等的部分。河纲发达的区域,占全国面积三分之一(杭爱区),其余干旱的地区,几乎完全没有河川(戈壁 区)。作者根据91次的分析,绘制了蒙古人民共和国河川水矿化度草图。确定了河水矿化度的变化是自30.1毫克/公升(科布多河)至1592毫克/公升 (南曼科多-鸟拉山脈北麓诸溪涧)。河川水所含的矿化度一般都不很高。河川水的化学亲合力是垂直带状分布的,这种分
[12]	王菱, 甄霖, 刘雪林, 等. 蒙古高原中部气候变化及影响因素比较研究 . 地理研究, 2008, 27(1): 171-180.https://doi.org/10.3321/j.issn:1000-0585.2008.01.019URLMagsci [本文引用: 1]摘要 利用蒙古国中部6个气象站1940-2004年和中国内蒙古自治区中部6个气象站1951～2004年的温度和降水资料，对两地的气候变化及其影响因素作了对比研究。结果表明：20世纪90年代与60年代相比，中国内蒙古6站平均升温1．35℃，蒙古国6站上升1．13℃，2000-2004年与60年代相比：中国内蒙古6站上升1．89℃，蒙古国则为1．37℃，中国内蒙古6站的升温速率高于蒙古国6站。对温度变化趋势作突变性检验，结果表明：温度发生突变时间是纬度较高地区早于纬度较低的地区，大城市早于中小城镇，城市化对温度变化影响比较明显。相对于温度变化，降水变化没有显著性的突变，但有周期变化，中国内蒙古降水变化有2．8年周期，蒙古国有4年、8年的周期，这可能因为中国内蒙古降水水汽主要来源于太平洋，而蒙古国降水的水汽主要来源于北冰洋。 [Wang Ling, Zhen Lin, Liu Xuelin, et al.Comparative studies on climate changes and influencing factors in central Mongolian Plateau region. Geographical Research, 2008, 27(1): 171-180.]https://doi.org/10.3321/j.issn:1000-0585.2008.01.019URLMagsci [本文引用: 1]摘要 利用蒙古国中部6个气象站1940-2004年和中国内蒙古自治区中部6个气象站1951～2004年的温度和降水资料，对两地的气候变化及其影响因素作了对比研究。结果表明：20世纪90年代与60年代相比，中国内蒙古6站平均升温1．35℃，蒙古国6站上升1．13℃，2000-2004年与60年代相比：中国内蒙古6站上升1．89℃，蒙古国则为1．37℃，中国内蒙古6站的升温速率高于蒙古国6站。对温度变化趋势作突变性检验，结果表明：温度发生突变时间是纬度较高地区早于纬度较低的地区，大城市早于中小城镇，城市化对温度变化影响比较明显。相对于温度变化，降水变化没有显著性的突变，但有周期变化，中国内蒙古降水变化有2．8年周期，蒙古国有4年、8年的周期，这可能因为中国内蒙古降水水汽主要来源于太平洋，而蒙古国降水的水汽主要来源于北冰洋。
[13]	Ju J T, Zhu L P, Wang J B, et al.Water and sediment chemistry of Lake Pumayum Co, South Tibet, China, implications for interpreting sediment carbonate. Journal of Paleolimnology, 2010, 43(3): 463-474.https://doi.org/10.1007/s10933-009-9343-6URLMagsci [本文引用: 1]摘要 ABSTRACT A combination of water and sediment chemistry was used to investigate carbonate production and preservation in Lake Pumayum Co (altitude 5,030ma.s.l.), south Tibet, China. We compared the chemical composition of lake water in various parts of the lake with that of input rivers and found that the loss of Ca2+ results from calcite sedimentation induced by evaporation and biogenic precipitation. This is supported by evaporation data from the catchment and 18O measurements on water. Results suggest that CaCO3 is the predominant carbonate in this lake. There is a positive correlation in the sediments among concentrations of total inorganic carbon (TIC), Ca, total organic carbon (TOC), and total nitrogen, confirming that most carbonates in sediment are endogenic. The Jiaqu River is the largest inflow to Lake Pumayum Co and has a strong influence on both lake water chemistry and sediment composition. The river and lake bathymetry influence carbonate sedimentation by affecting water flow velocity and growing conditions for macrophytes. Different carbon contents and relationships between TIC and TOC in the two long cores from different depths in the lake reveal that hypolimnetic conditions also influence carbonate precipitation and preservation. KeywordsCarbonate-Lake sediments-Tibetan Plateau-Water chemistry-Spatial distribution-Lake Pumayum Co
[14]	Wu W H, Xu S J, Yang J D, et al.Silicate weathering and CO2 consumption deduced from the seven Chinese rivers originating in the Qinghai-Tibet Plateau. Chemical Geology, 2008, 249(3-4): 307-320.https://doi.org/10.1016/j.chemgeo.2008.01.025URL [本文引用: 1]摘要 ABSTRACT We present river chemical data for the seven Chinese rivers (the Jinsha Jiang, Yalong Jiang, Min Jiang, Dadu He, Lancang Jiang, Nu Jiang and Huang He) originating in the Qinghai–Tibet Plateau. Our sampling locations are near sites where the seven rivers flow down the plateau. Water samples were collected in both high-water periods (summer) and low-water periods (winter). Our study shows that most of the Ca, Mg and HCO3 in the seven rivers are derived from the carbonate weathering and only small fractions (10%) of the cations are derived from silicate weathering. The chemical erosion rates of silicate and carbonate range from 1.1 mm ka61 1 to 3.4 mm ka61 1 and from 7.5 mm ka61 1 to 29.9 mm ka61 1 respectively. The long term CO2 consumption by silicate weathering in the seven Chinese river basins ranges from 0.7 × 105 mol km61 2 a61 1 to 3.7 × 105 mol km61 2 a61 1. Based on our analysis of chemical data from the seven Chinese rivers and the previously published data of the Ganges, Brahmaputra and Indus, the main ten rivers originating in the Himalaya and Qinghai–Tibet Plateau consume 328 × 109 mol a61 1 of atmospheric CO2. This is only 3.8% of the CO2 consumption derived from global silicate weathering (8700 × 109 mol a61 1), indicating that the chemical weathering of the Himalaya and Qinghai–Tibet Plateau makes a very small contribution to the reduction of the global atmospheric CO2 concentration.
[15]	Li S Y, Zhang Q F.Geochemistry of the upper Han River Basin, China, 1: Spatial distribution of major ion compositions and their controlling factors. Applied Geochemistry, 2008, 23(12): 3535-3544.https://doi.org/10.1016/j.apgeochem.2008.08.012URLMagsci [本文引用: 2]摘要 ABSTRACT The upper Han River basin (approximately 95,200 km2) is the water source area of China’s South-to-North Water Transfer Project. Over the period from 2005 to 2006, a total of 292 grab samples collected from 47 sites in the upper Han River were analyzed for major ions (Cl61, , , , Na+, K+, Ca2+ and Mg2+), Si, T, pH, EC and TDS. Correlation matrix and principal component analysis were used to quantify the geochemical and anthropogenic processes and identify factors influencing the ionic concentrations. The results reveal that the waters are slightly alkaline with low ionic strength, and all ions show remarkable spatial variations. The lowest solute concentrations are observed in catchment with higher vegetation cover, with higher Cl61, and concentrations occur in catchments with industrial establishments. The major ion chemistry of the upper Han River basin is mainly controlled by rock weathering with and Ca261 dominating the major ion composition. The spatial variation in overall water quality as well as comparison with WHO and Chinese standards for drinking water indicates that the basin has high-water quality, yet it is possible that enrichment will occur in the near future. This research will help water conservation in the basin for the interbasin water transfer project.
[16]	Gibbs R J.Mechanisms controlling world water chemistry. Science, 1970, 170(3962): 1088-1090.https://doi.org/10.1126/science.170.3962.1088URLPMID:17792946 [本文引用: 1]摘要 On the basis of analytical chemical data for numerous rain, river, lake, and ocean samples, the three major mechanisms controlling world surface water chemistry can be defined as atmospheric precipitation, rock dominance, and the evaporation-crystallization process.
[17]	Stallard R F, Edmond J M.Geochemistry of the Amazon 1: Precipitation chemistry and the marine contribution to the dissolved load at the time of peak discharge. Journal of Geophysical Research, 1981, 86(NC10): 9844-9858.https://doi.org/10.1029/JC086iC10p09844URL [本文引用: 1]摘要 ABSTRACT Analyses of precipitation and surface water are used to estimate the fluxes of marine cyclic salts through that part of the Amazon River system draining past Obidos (80% of the basin) at the time of peak discharge in June. Amazon precipitation chemistry can be devided into two principal components: marine and terrestrial. The marine component (determined from analyses of marine rain) consists of Na, K, Mg, Ca, and Cl in approximately sea-salt proportions, with S doubly enriched. The excess sulfur is probably derived from gas phase inputs. The terrestrial component makes an important contribution of K, Ca, S, and N, much of which can be related to biological emissions. The emission of reduced sulfur in the marine and terrestrial environment and nitrogen in the terrestrial environment is responsible for a natural cid rain in the Amazon region with a pH from 4.7 to 5.7. This is about one tenth the acidity of polluted urban rain. The chloride content of lowland rivers, which drain regions lacking significant geologic sources of chloride, shows a systematic decrease in chloride with increasing distance from the ocean. This trend is used to define the cyclic salt background for Amazonian surface waters. Cyclic salts, in general, make only a minor contribution, relative to terrestrial inputs, to the chemistry of Amazon Basin rivers, even those draining intensely weathered terrains. An estimated 17.6%-Cl, 6.9%-Na, 1.3%-Mg, 3.6%-S, 0.4%-K, and 0.1%-Ca of the dissolved load at Obidos during peak discharge is cyclic.
[18]	Li S Y, Xu Z F, Wang H, et al.Geochemistry of the upper Han River Basin, China, 3: Anthropogenic inputs and chemical weathering to the dissolved load. Chemical Geology, 2009, 264(1): 89-95.https://doi.org/10.1016/j.chemgeo.2009.02.021URL [本文引用: 3]摘要 The study focuses on the chemical and trace element compositions of the dissolved load in the upper Han River, the water source area of the Middle Route of China's South-to-North Water Transfer Project. Water samples were collected in the high flow period and analyzed for cations by Inductively Coupled Plasma Atomic Emission Spectrometer and anions by ionic chromatography respectively, in order to understand the contributions of anthropogenic activities and rock weathering to river solutes, as well as the associated CO2consumption in the carbonate-dominated basin. The river waters have a mean TZ+ of 2674 μeq/l ranging from 1034.3 to 4611.6 μeq/l, which is significantly higher than that of the global river waters. Calcium and HCO361, followed by Mg2+ and SO4261, dominate the chemical composition of major species in the basin. There are three major reservoirs (carbonates, silicates and agriculture/urban effluents) contributing to the dissolved load in the river. Chemical weathering rate is approximately 53.1 t/km2/yr with respective carbonate and silicate weathering rates of 47.5 t/km2/yr (19.8 mm/kyr) and 5.6 t/km2/yr (2.1 mm/kyr). The CO2consumption is estimated to be 64.69 × 109 mol/yr and 9.69 × 109 mol/yr by carbonate and silicate weathering, respectively. The contribution of the anthropogenic inputs to the dissolved load is estimated to be 16.7%, demonstrating the strong impacts of human activities on water chemistry.
[19]	Grosbois C, Negrel P H, Fouillac C, et al.Dissolved load of the Loire River: Chemical and isotopic characterization. Chemical Geology, 2000, 170(1-4): 179-201.https://doi.org/10.1016/S0009-2541(99)00247-8URL [本文引用: 1]摘要 The aim of this study is to describe the mixing model in order to estimate the contribution of each component. Finally, specific export rates in the upper Loire watershed were evaluated close to 12 t year 611 km 612 for the silicate rate and 47 t year 611 km 612 for the carbonate rate.
[20]	Meybeck M.Global chemical weathering of surficial rocks estimated from river dissolved loads. American Journal of Science, 1987, 287(5):401-428.https://doi.org/10.2475/ajs.287.5.401URL [本文引用: 1]摘要 ABSTRACT. Combination of water analyses characteristic of major rock types with their relative outcrop proportions at the surface of the continents leads to a theoretical average composition of river waters close to the actual measured value. The representative anal-
[21]	Sarin M M, Krishnaswami S, Dilli K, et al.Major ion chemistry of the Ganga-Brahmaputra river system: Weathering processes and fluxes to the Bay of Bengal. Geochimica et Cosmochimica Acta, 1989, 53(5): 997-1009.https://doi.org/10.1016/0016-7037(89)90205-6URL [本文引用: 1]摘要 The Ganga-Brahmaputra, one of the world's largest river systems, is first in terms of sediment transport and fourth in terms of water discharge. A detailed and systematic study of the major ion chemistry of these rivers and their tributaries, as well as the clay mineral composition of the bed sediments has been conducted. The chemistry of the highland rivers (upper reaches of the Ganga, the Yamuna, the Brahmaputra, the Gandak and the Ghaghra) are all dominated by carbonate weathering; (Ca + Mg) and HCO account for about 80% of the cations and anions. In the lowland rivers (the Chambal, the Betwa and the Ken), HCO excess over (Ca + Mg) and a relatively high contribution of (Na + K) to the total cations indicate that silicate weathering and/or contributions from alkaline/saline soils and groundwaters could be important sources of major ions to these waters. The chemistry of the Ganga and the Yamuna in the lower reaches is by and large dictated by the chemistry of their tributaries and their mixing proportions. Illite is the dominant clay mineral (about 80%) in the bedload sediments of the highland rivers. Kaolinite and chlorite together constitute the remaining 20% of the clays. In the Chambal, Betwa and Ken, smectite accounts for about 80% of the clays. This difference in the clay mineral composition of the bed sediments is a reflection of the differences in the geology of their drainage basins. The highland rivers weather acidic rocks, whereas the others flow initially through basic effusives. The Ganga-Brahmaputra river system transports about 130 million tons of dissolved salts to the Bay of Bengal, which is nearly 3% of the global river flux to the oceans. The chemical denudation rates for the Ganga and the Brahmaputra basins are about 72 and 105 tons km yr , respectively, which are factors of 2 to 3 higher than the global average. The high denudation rate, particularly in the Brahmaputra, is attributable to high relief and heavy rainfall.
[22]	WHO. Guidelines for Drinking-Water Quality, the 3rd Edition Volume 1: Recommendations. Geneva: Word Health Organization, 2006. [本文引用: 1]
[23]	Carpenter S R, Caraco N F, Correll D L, et al.Non-point pollution of surface waters with phosphorus and nitrogen. Ecological Applications, 1998, 8(3): 559-568.https://doi.org/10.2307/2641247URL [本文引用: 1]摘要 ABSTRACT Agriculture and urban activities are major sources of phosphorus and nitrogen to aquatic ecosystems. Atmospheric deposition further contributes as a source of N. These nonpoint inputs of nutrients are difficult to measure and regulate because they derive from activities dispersed over wide areas of land and are variable in time due to effects of weather. In aquatic ecosystems, these nutrients cause diverse problems such as toxic algal blooms, loss of oxygen, fish kills, loss of biodiversity (including species important for commerce and recreation), loss of aquatic plant beds and coral reefs, and other problems. Nutrient enrichment seriously degrades aquatic ecosystems and impairs the use of water for drinking, industry, agriculture, recreation, and other purposes. Based on our review of the scientific literature, we are certain that (1) eutrophication is a widespread problem in rivers, lakes, estuaries, and coastal oceans, caused by over-enrichment with P and N; (2) nonpoint pollution, a major source of P and N to surface waters of the United States, results primarily from agriculture and urban activity, including industry; (3) inputs of P and N to agriculture in the form of fertilizers exceed outputs in produce in the United States and many other nations; (4) nutrient flows to aquatic ecosystems are directly related to animal stocking densities, and under high livestock densities, manure production exceeds the needs of crops to which the manure is applied; (5) excess fertilization and manure production cause a P surplus to accumulate in soil, some of which is transported to aquatic ecosystems; and (6) excess fertilization and manure production on agricultural lands create surplus N, which is mobile in many soils and often leaches to downstream aquatic ecosystems, and which can also volatilize to the atmosphere, redepositing elsewhere and eventually reaching aquatic ecosystems. If current practices continue, nonpoint pollution of surface waters is virtually certain to increase in the future. Such an outcome is not inevitable, however, because a number of technologies, land use practices, and conservation measures are capable of decreasing the flow of nonpoint P and N into surface waters. From our review of the available scientific information, we are confident that: (1) nonpoint pollution of surface waters with P and N could be reduced by reducing surplus nutrient flows in agricultural systems and processes, reducing agricultural and urban runoff by diverse methods, and reducing N emissions from fossil fuel burning; and (2) eutrophication can be reversed by decreasing input rates of P and N to aquatic ecosystems, but rates of recovery are highly variable among water bodies. Often, the eutrophic state is persistent, and recovery is slow.
[24]	张雪艳, 胡云锋, 庄大方, 等. 蒙古高原NDVI的空间格局及空间分异 . 地理研究, 2009, 28(1): 10-18.https://doi.org/10.3321/j.issn:1000-0585.2009.01.002URLMagsci [本文引用: 1]摘要 基于GIMMS NDVI多年最大值合成数据,采用空间统计学方法,利用Moran’s I系数分析、半变异函数分析以及分维分析等3种方法,对蒙古高原NDVI空间格局及空间分异特征进行研究。结果表明:(1)蒙古高原NDVI的空间分布在全局范围内呈现正的空间自相关,相似的NDVI值倾向于聚集在一起,这表明蒙古高原植被具有较好的整体性,地表植被无显著破碎化;(2)蒙古高原NDVI的空间分布虽然同时受到结构性因子和随机性因子的影响,但结构性因子占据绝对控制地位,结构性因子引起的空间变异占系统总变异的88.7%;(3)蒙古高原NDVI存在各向异性的分布特征,具有相似NDVI值的像元主要沿着西北-东南方向展布;全局NDVI空间自相关距离约为1178km,西北-东南方向与东北-西南方向的空间自相关距离比可达2.4∶1。 [Zhang Xueyan, Hu Yunfeng, Zhuang Dafang, et al.The spatial pattern and differentiation of NDVI in Mongolia Plateau. Geographical Research, 2009, 28(1): 10-18.]https://doi.org/10.3321/j.issn:1000-0585.2009.01.002URLMagsci [本文引用: 1]摘要 基于GIMMS NDVI多年最大值合成数据,采用空间统计学方法,利用Moran’s I系数分析、半变异函数分析以及分维分析等3种方法,对蒙古高原NDVI空间格局及空间分异特征进行研究。结果表明:(1)蒙古高原NDVI的空间分布在全局范围内呈现正的空间自相关,相似的NDVI值倾向于聚集在一起,这表明蒙古高原植被具有较好的整体性,地表植被无显著破碎化;(2)蒙古高原NDVI的空间分布虽然同时受到结构性因子和随机性因子的影响,但结构性因子占据绝对控制地位,结构性因子引起的空间变异占系统总变异的88.7%;(3)蒙古高原NDVI存在各向异性的分布特征,具有相似NDVI值的像元主要沿着西北-东南方向展布;全局NDVI空间自相关距离约为1178km,西北-东南方向与东北-西南方向的空间自相关距离比可达2.4∶1。