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地理研究 >

2016 , Vol. 35 >Issue 10: 1887 - 1898

DOI: https://doi.org/10.11821/dlyj201610008

研究论文

沅江下游入湖段河床沉积物重金属污染特征

  • 方小红 , 1 ,
  • 彭渤 , 1, 2 ,
  • 张坤 1 ,
  • 曾等志 1 ,
  • 匡晓亮 1 ,
  • 吴蓓娟 1 ,
  • 谭长银 1, 2 ,
  • 王欣 1, 2
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  • 1. 湖南师范大学资源与环境科学学院, 长沙 410081
  • 2. 湖南师范大学环境重金属污染机理与生态修复实验室, 长沙 410081
通讯作者：彭渤（1965- ）,男,湖南祁东人,教授,博士,主要从事矿床地质及环境地球化学研究。E-mail:

作者简介：方小红（1990- ）,女,湖北麻城人,硕士,主要从事环境地球化学研究。E-mail:

收稿日期: 2016-04-13

  要求修回日期: 2016-07-25

  网络出版日期: 2016-10-26

基金资助

国家自然科学基金项目（41073095,41071216）

湖南省高校科技创新团队支持计划（2014）

收起

Heavy metal contamination of bed sediments in inlet area of the lowermost Yuanjiang River, Hunan province of China

  • FANG Xiaohong , 1 ,
  • PENG Bo , 1, 2 ,
  • ZHANG Kun 1 ,
  • ZENG Dengzhi 1 ,
  • KUANG Xiaoliang 1 ,
  • WU Beijuan 1 ,
  • TAN Changyin 1, 2 ,
  • WANG Xin 1, 2
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  • 1. Faculty of Resource and Environment Sciences, Hunan Normal University, Changsha 410081, China
  • 2. Key Laboratory of Environmental Heavy-Metal Contamination and Ecological Remediation, Hunan Normal University, Changsha 410081, China

Received date: 2016-04-13

  Request revised date: 2016-07-25

  Online published: 2016-10-26

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《地理研究》编辑部
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摘要

对沅江入湖沉积物进行钻探取样,利用等离子质谱仪（ICP-MS）对沉积物重金属进行分析。结果表明：重金属Ba、Sc、V、Th、U、Cu、Co、Ni、Cr等在沉积物中含量变化相对稳定,分布相对均匀;而Mn、Zn、Pb、Mo、Cd、Tl、Bi等重金属的含量变化大,分布不均匀。重金属含量柱状剖面变化特征及富集系数（EF值）的计算结果显示：沉积物中Cd达显著富集,而Sc、V、Mn、Pb、Bi等为中等富集程度。沉积物中存在3个重金属富集层,即中下部Pb、Tl、Bi富集层;中上部Pb、Cr、Ni、Cu富集层;浅表部V、Cr、Mn、Ni、Cu、Zn、Pb、Cd、Tl、Bi等多种重金属富集层。地累积指数（Igeo）和综合富集指数（EI）评价结果显示：沅江入湖沉积物重金属污染程度自河床深部向浅部,污染程度趋于增强,污染元素组合趋于由Pb-Bi的单一元素组合向由V-Cr-Mn-Ni-Cu-Zn-Pb-Cd-Bi组成的复合元素组合变化。且自上游向下游,沉积物重金属污染程度趋于降低。这种重金属污染空间变化特征与区域人为活动有关,值得进一步研究。

关键词： 重金属富集; 重金属污染; 重金属污染空间变化; 河床沉积物; 沅江下游

本文引用格式

方小红 , 彭渤 , 张坤 , 曾等志 , 匡晓亮 , 吴蓓娟 , 谭长银 , 王欣 . 沅江下游入湖段河床沉积物重金属污染特征[J]. 地理研究, 2016 , 35(10) : 1887 -1898 . DOI: 10.11821/dlyj201610008

Abstract

The river inlet sediments were collected from three sediment cores sampled by drilling in the inlet area of the lowermost Yuanjiang River (China) in this study, and concentrations of heavy metals in the sediments were analyzed using the ICP-MS techniques. The results show that concentrations of heavy metals Ba, Sc, V, Th, U, Cu, Co, Ni and Cr in sediments are less variable, and they are relatively homogeneously distributed in all the sediments. However, concentrations of metals Mn, Zn, Pb, Mo, Cd, Tl and Bi are significantly variable, and they are distributed heterogeneously in the sediments. The depth variations of concentrations of the heavy metals in sediments of the three sediment cores suggest that there are three layers of sediments that are relatively enriched in different heavy metals. They are the middle-lower layer of sediments that are relatively enriched in heavy metals Pb, Tl and Bi; the middle-upper layer of sediments that are relatively enriched in heavy metals Pb, Cr, Ni and Cu; and the upper surface layer of sediments relatively enriched in heavy metals V, Cr, Mn, Ni, Cu, Zn, Pb, Cd, Tl and Bi. The principal analysis results show that most samples from the upper surface layer of sediments, and some from the middle-upper and middle-lower layers of sediments are enriched in different heavy metals. The degree of heavy-metal contamination is assessed using the geo-accumulation index (Igeo) and synthetic enrichment index (EI), and the results show that the degree of heavy metal contamination in the bed sediments of the lowermost river is increased from the middle lower to the upper surface layer of sediments, and along with such depth variation the contamination is changed from the single Pb-Bi assemblage to the complex V-Cr-Mn-Ni-Cu-Zn-Pb-Cd-Bi assemblage. Also the degree of the heavy metal contamination decreases from the upper river to the lower river sediments. Such spatial variation of heavy metal contamination in the bed river sediments of the lowermost Yuanjiang River is believed to be closely related to the corresponding anthropogenic events, which needs to be studied further.

Key words： heavy-metal enrichment; heavy metal contamination; spatial variation of the heavy-metal contamination; river-bed sediment; the lowermost Yuanjiang River

1 引言

沉积物是重要的环境介质[1,2],沉积物重金属污染是当前备受关注的环境问题[3-6]。一方面沉积物通过吸附、离子交换、共沉淀等方式集聚来自大气、水、土壤等环境单元的重金属,使之对环境重金属污染具有“缓冲”功能[1,6,7];另一方面,集聚了重金属的沉积物,由于环境条件（如氧化还原电位、酸碱条件等）的变化,其中的重金属可被释放迁出,使之成为重金属污染源,产生“二次污染”[2,8]。因此,人为作用背景下的沉积物重金属污染问题,是当前环境地球化学研究的重要内容之一。
洞庭湖是中国主要淡水湖,是全国重要的粮、棉、油和渔业基地[5,9]。由于采矿、排污等各种人为作用使湖区重金属污染问题十分突出[2,4-6,10-15]。因而对洞庭湖沉积物重金属污染研究一直受到重视。例如,最早对沉积物重金属背景值的分析[16],最近对沉积物重金属污染评价[4-6,10-15]、重金属污染源的Pb同位素示踪研究[2,17-19]等。在已有的研究中,湘江入湖沉积物重金属污染问题已受到特别关注[2,4-6,17-21],而对沅江等其余河流入湖沉积物重金属污染的专门分析还很欠缺。且早期的分析认为洞庭湖“四水”入湖沉积物存在严重的重金属污染[11,17],而近年的分析认为西洞庭（沅江入湖）沉积物仅存在轻度的Cd、Hg重金属污染[9,10]。已有的工作主要针对表层沉积物进行分析和评价[10-15],对深部沉积物重金属的分析尚很缺乏。就沅江下游入湖沉积物而言,仅有少数文献对其重金属污染进行了研究[5,10,11]。本文对沅江入湖沉积物进行钻探取样,试图对其重金属污染作进一步的分析。

2 研究区概况

沅江自贵州东南部入湖南,经洪江北上,于沅陵东拐后,由常德汇入西洞庭湖。地质上,沅江流域主体分布在雪峰山弧形构造带的南端及其西北侧。河流切割的地层主要为：元古界冷家溪群变质板岩和板溪群变质砂板岩,早古生界震旦—寒武—奥陶系海相沉积碎屑岩夹薄层灰岩,晚古生界泥盆系砂岩和石炭—二叠系灰岩,及中新生界白垩—古近系陆相红色碎屑岩和局部分布的三叠—侏罗系灰岩[22]。河流上游雪峰山构造区是中国著名的金—锑矿成矿域,大、小金—锑矿床星罗棋布。且区内矿床开采的历史可追溯到1875年[23,24]。
沅江流域在湖南境内面积为5.1万 km2,是洞庭湖重要水系之一。流域位于亚热带季风湿润气候区,年平均气温16.6 ℃,降水1400 mm。以桃源县为界限,其西北上游为山区,其以东下游属低山丘陵区,河谷宽阔。桃源以下洞庭湖入湖河段为滨湖相冲积平原,沿河地势低洼,平均比降仅0.2 ‰ ,沉积物广泛分布。

3 样品采集与分析方法

3.1 样品采集与描述

对沅江下游入湖河段进行野外调查和沉积物取样。利用课题组与亿捷公司联合设计的ZYA-70型沉积物取样器进行沉积物钻探取样。该取样器借助动力推进器和3根长100 cm、外径58 mm、内径52 mm的不锈钢管,可取得总长300 cm的沉积柱样。2015年1月,选择牛鼻滩、沅江大桥、岩汪湖三地进行沉积柱芯钻探取样,取得的沉积柱样品依次分别命名为YN、YJ、YW沉积柱,沉积柱位置如图1所示。
Fig. 1 Map showing location of the sediment cores sampled in inlet area of the lowermost Yuanjiang River

图1 沅江下游入湖河段沉积柱采样位置图示

自不锈钢管推出后,得到YN、YJ、YW沉积柱样品,长度分别为263 cm、286 cm、276 cm（因挤压未得到300 cm长的沉积柱）（图2）。其中,YN沉积柱分层不明显,但自上而下可分成4个颜色段,即第1段褐黄或黄褐色粉砂质淤泥层,见白云母碎片和植物残枝,长68 cm;第2段为褐黄深黑色淤泥,见白云母碎片和动植物残体,长48 cm;第3段褐灰、灰黑色淤泥,见白云母碎片,长64 cm;第4段褐黑、褐灰黑色粉砂质淤泥,见白云母碎片,长83 cm。YJ沉积柱自上而下也分为3个颜色段,即顶部第1段褐黄或黄褐色粉砂质淤泥,见云母碎片和植物残枝,长72 cm;中部第2段黄褐灰色粉砂质淤泥层,未见云母碎片和植物残枝,颜色变深,长104 cm;底部第3段灰黑褐、灰黑色粉砂质淤泥,长110 cm。YW沉积柱自上而下也分3个颜色段,即顶部第1段褐黄或黄褐色粉砂质淤泥层,见白云母碎片和植物残枝,长88 cm;中部第2段黄褐、灰黑色粉砂质淤泥层,未见云母碎片和植物残枝,长92 cm;底部第3段灰黑、黄褐色粉砂质淤泥,未见云母碎片和植物残枝,长96 cm。总体上,3个沉积柱沉积物颜色均自上而下趋于变深,但各颜色段沉积物岩性无明显差别,主要为粉砂质或含粉砂质的淤泥（图2）。野外获得沉积柱样品后,进行观察记录拍照,然后按4 cm的间距分样,获得沉积物样品,YN、YJ、YW依次分别获得样品65件、69件、68件,样品分布如图2所示。样品装入干净的塑料封口袋带回实验室。
Fig. 2 Photos showing the sediment cores and the location of sediment samples collected from each cores sampled in inlet area of the lowermost Yuanjiang River

图2 沅江下游入湖河段沉积柱样品及沉积物样品分布图

3.2 样品分析

室内沉积物样品自然风干后,置入烘箱于40 ℃条件下烘干,再将泥团沉积物样品捣碎,剔除植物残枝和砾石,过60目筛。称取60目样品5.0 g用玛瑙研钵研磨,过200目（<75 μm）筛,得到的粉末样品置于洁净的封口袋中,备用。
由于沉积物岩性较均一,本次工作选择编号为单数的沉积物样品进行分析。沉积物样品的重金属和Al2O3含量分析在中国科学院广州地球化学研究所同位素地球化学国家重点实验室进行。重金属利用Perkin-Elmer Elan 6000型等离子质谱仪（ICP-MS）测定。40.0 mg粉末样品置于Teflon容器中,加0.8 mL HNO3（1 ∶ 1）和0.8 mL HF,再加入HClO4（1 ∶ 3）后,密封超声震荡60 s后,恒温加热（100 ℃）2 d后,蒸干。然后,加入0.8 mL的HNO3（1 ∶ 1）,恒温加热（100 ℃）24 h后蒸干。再加入0.8 mL HF + HClO4,密封置高压釜中,于170 ℃烘箱内加热48 h,蒸干。再加入4N的HNO3 4 mL,于170 ℃烘箱内再加热4 h。以3% HNO3稀释并移至50 mL的容量瓶。加入Rh-Re内标液,以1% HNO3至稀释至40.0 g备ICP-MS分析。质谱仪工作条件：RF功1000~1100 W,雾化器流速1.14 L/min,透镜电压为自动聚焦,扫描方式为跳峰,积分时间为100 ms。样品分析用国家标准样GSR-3进行5次平行测定,检测极限达10×10-9,分析精度优于5%[25]。
沉积物Al2O3含量分析利用X射线荧光光谱分析仪（XRF）进行。样品处理、仪器工作条件、标准样品等参见文献[21]。沉积物有机质用重铬酸钾—硫酸消化法[26]测定。

4 结果分析

3个沉积柱沉积物重金属含量分析结果的Kolmogorov-Smirnov 检验符合正态分布（Z>0.05）。沉积物Sc等16种重金属（广义）的含量分析结果统计如表1所示。从表1可以看出,在这16种重金属中,Ba、Sc、V、Th、U、Cu、Co、Ni、Cr等重金属在各沉积柱沉积物中含量变化相对稳定（变异系数Cv < 0.15,除Ni、Cr在YN沉积柱沉积物中含量变化较大外）,且各沉积柱沉积物中相应重金属有大致相近的含量值,如Ba在YN、YJ、YW沉积柱沉积物中的平均含量依次分别为765.8 mg/kg、726.8 mg/kg、639.2 mg/kg（依次样品数n=33、35、34,下同）。说明这些重金属在沅江入湖沉积物中的分布比较均匀。但Mn、Zn、Pb、Mo、Cd、Tl、Bi等重金属在各沉积柱沉积物中的含量变化较大（Cv>0.20）,且它们在各沉积柱沉积物中的含量有依YN、YJ、YW的顺序而趋于降低的变化趋势,如Mn在各沉积柱沉积物中的平均含量依次为1124 mg/kg、1039 mg/kg、790 mg/kg,即YN沉积柱之沉积物明显相对富集这些重金属。而YN沉积柱正好靠近常德市市区（图1）,故沉积物中分布很不均一、于YN沉积柱沉积物中相对富集的重金属,可能与人为活动有关。
Tab. 1 Statistic results of concentrations of heavy metals (mg/kg), organic matter (mass %) and Al2O3 (mass %) in the bed sediments from the lowermost Yuanjiang River

表1 沅江入湖沉积物重金属(mg/kg)、有机质(mass %)和Al2O3 (mass %)含量统计结果

沉积柱 YN (n = 33) YJ (n =35) YW (n = 34) 背景
值[14]
最小值 最大值 平均值 Cv 最小值 最大值 平均值 Cv 最小值 最大值 平均值 Cv
Ba 590.0 919.5 765.8 0.09 532.5 786.4 726.8 0.08 394.5 991.2 639.2 0.15 554.1
Sc 10.66 16.68 13.65 0.12 9.664 16.1 13.4 0.09 10.67 15.55 12.4 0.09 6.8
V 76.32 128.2 103.6 0.14 66.32 111.7 97.8 0.10 74.32 143.8 92.2 0.13 42.0
Th 13.41 17.97 16.1 0.07 11.25 25.59 15.2 0.16 12.62 17.16 14.6 0.07 14.8
U 3.749 4.669 4.20 0.05 2.861 5.552 3.84 0.15 3.376 5.230 4.13 0.11 3.6
Cu 25.49 50.29 33.1 0.14 23.04 40.56 32.4 0.12 23.46 49.30 29.1 0.15 20.0
Co 11.66 18.02 15.4 0.13 10.96 17.75 15.4 0.09 11.73 19.10 14.7 0.10 10.3
Ni 25.14 177.9 41.1 0.62 21.54 44.10 35.5 0.13 24.34 54.47 33.4 0.17 21.2
Cr 57.45 215.0 78.2 0.34 50.49 102.4 74.8 0.16 53.25 118.2 72.9 0.15 44.0
Mn 468.0 2158.2 1124 0.35 336.6 1976.6 1039 0.40 334.8 2375.1 790.2 0.51 450
Zn 79.88 241.0 134.8 0.29 77.35 223.4 127.1 0.28 82.07 270.0 110.0 0.36 76.0
Pb 27.74 68.72 43.7 0.21 22.72 63.42 36.4 0.23 24.40 63.85 33.5 0.23 22.0
Mo 1.293 30.76 2.72 1.86 1.079 2.637 1.68 0.22 1.196 2.441 1.49 0.16 1.65
Cd 0.719 13.25 2.97 1.12 0.611 7.251 1.96 0.97 0.596 9.100 1.56 1.26 0.33
Tl 0.536 0.868 0.71 0.13 0.482 1.044 0.70 0.12 0.56 0.877 0.67 0.09 0.60
Bi 0.369 1.027 0.61 0.24 0.281 1.849 0.49 0.54 0.302 0.736 0.41 0.26 0.30
OM 0.1826 0.1831 0,1829 0.0008 - - - - -0.1168 0.3501 0.177 0.5895
Al2O3 10.09 16.38 13.96 0.11 10.75 15.25 13.65 0.07 11.33 16.02 12.97 0.08 12.28

注：OM为有机质含量;-表示无分析结果。

沉积柱沉积物重金属含量垂向变化如图3所示。可以看出：① 沉积物中分布相对均匀的重金属V、Cr、Ni、Cu、Ba、Sc、Th、U、Co等（后5种重金属在图3中未标出）,含量在沉积柱剖面上明显不随深度而变化,但V、Cr、Ni、Cu等在浅表部（0~64 cm）沉积物中的含量明显趋于升高（图3a、图3b、图3d、图3e）。而Mn、Zn、Pb、Cd、Tl、Bi等在沉积物中分布明显不均匀的重金属,其含量在沉积柱剖面上明显趋于在浅表部（0~64 cm）沉积物中升高（图3、图3f~图3j）;显示V、Cr、Ni、Cu、Mn、Zn、Pb、Cd、Tl、Bi等重金属趋于在浅表部沉积物中明显相对富集。② 沉积柱192 cm处沉积物中明显相对富集Pb、Tl、Bi等重金属（图3g、图3i、图3j）,而在64~96 cm处明显相对富集Pb、Cr、Ni、Cu等重金属（图3b、图3d、图3e、图3g）。③ 3个沉积柱相比,含量变化大的重金属Mn、Zn、Pb、Cd、Tl、Bi等,其含量从沉积柱底部到浅部都显示YN沉积物高于YJ、YW沉积物的水平空间变化特征（图3c、图3f~图3j）。而分布相对均匀的重金属则不然。综上,沅江入湖沉积物垂向剖面上有3层沉积物存在重金属的相对富集：第1层是中下部192 cm处沉积物,明显相对富集Pb、Tl、Bi等;第2层是中上部96~64 cm处沉积物,明显相对富集Pb、Cr、Ni、Cu等;第3层是浅表部64 cm以上的沉积物,明显相对富集V、Cr、Mn、Ni、Cu、Zn、Pb、Cd、Tl、Bi等多种重金属。上述3层沉积物重金属的明显相对富集现象,可能与3次区域人为作用有关。
Fig. 3 Plots showing the depth variations of concentrations of heavy metals in the Yuanjiang

图3 沅江入湖沉积柱重金属含量折线图

在这些重金属中,Sc与代表细粒黏土矿物的Al2O3[27,28]含量呈明显线性正相关关系（图4a）,显示明显的粒度效应。其余重金属的粒度效应总体不明显,但YW沉积柱之沉积物中,重金属V、Co、Cu、Ba、Tl等与Al2O3线性正相关关系明显（r2依次为0.79、0.78、0.54、0.57、0.82）,显示不同程度的粒度效应。另外,所有重金属与有机质含量之间无明显的相关性,如YW沉积柱沉积物Cd与有机质含量关系（图4b）。说明与湘江入湖沉积物[21]不同,沅江入湖沉积物重金属富集与有机质关系不密切。
Fig. 4 Plots of concentrations of metal Sc to Al2O3 (a) and of metal Cd to organic matters (b)

图4 重金属Sc与Al2O3（a）及YW沉积柱重金属与有机质含量（b）的相关性图示

5 讨论

5.1 沉积物重金属富集特征

用重金属的富集系数（EF）,来表征沉积物重金属富集特征[27],具体的计算公式为：
EF = ( X / M ) sample / ( X / M ) background （1）
式中： ( X / M ) sample 为样品中某重金属X对参照元素M的含量比值; ( X / M ) background 为某重金属X对参考元素M的背景值之比值。可见,沉积物重金属富集系数值的计算结果取决于背景值的确定和参照元素的选取。为便于与湘江沉积物重金属富集特征[2,17,21]对比,这里仍参照洞庭湖流域沉积物元素背景值[17]为式（1）中的背景值,以反映细粒黏土矿物组成的主量元素Al为参照元素。
Fig. 5 Box-plot of EF values of heavy metals in sediments of the YN, YJ and YW cores in inlet sediments of the Yuanjiang River

图5 沅江入湖沉积物重金属富集系数箱形图

计算得到3个沉积柱沉积物重金属的富集系数统计箱图（图5）。参照Sutherland富集程度的评判标准[27]（EF≤1.5,无明显富集;1.5<EF≤5,中等富集;5<EF≤20,显著富集;20<EF≤40,高度富集;EF>40,极度富集）,可见,除Cd为显著富集（YW沉积柱中为中等富集）外,Sc、V、Mn、Pb、Bi等可达中等富集,其余重金属富集不明显。故与湘江入湖沉积物存在Bi、Cu、Pb、Zn、Cd等多种重金属的高强度富集[2,17,21]不同,沅江入湖沉积物重金属富集强度较弱,富集重金属的种类较少。

5.2 富集重金属的沉积物判别

沅江入湖沉积物重金属富集总体不明显（图3、图5）。为把有重金属富集的沉积物与无重金属富集的沉积物区分开来,先将重金属含量分析结果用Al进行标准化,以消除粒度效应。再将所有沉积物样品（n=102,下同）重金属进行主成分分析（PCA）,求出因子贡献率和各个样品在主成分上的得分,进而通过样品得分对富集重金属的沉积物样品进行判别[28]。3个沉积柱沉积物重金属主成分计算的KMO测度值为0.761,且Bartlett球度检验相伴概率为0,故本文得到的分析数据适合因子分析处理[29]。样品可以由F1、F2、F3这3个主成分体现出来,3个主成分反应所有信息的75%（42.1%+17.5%+15.4%）,有很高的代表水平。样品重金属对主成分的贡献率之主成分F1对F2的投影图如图6所示。在F1-F2的二维展开图上,沉积物样品在-0.5<F1<+0.5及-1.5<F2<+0.5的区域集中,在此区域外的样品明显离散。将图6与图2、图3进行对比,可见离散在上区域外的样品（得分异常）大多正好是富集重金属的表层沉积物样品。这样,主成分分析的F1-F2二维展开图就可将富集重金属的沉积物样品区分出来（图6）。这些富集重金属的沉积物包括表层（64~0 cm沉积段）沉积物样品YN1~YN15、YJ1-1~YJ1-17、YW1~YW9,及中下部YN21、YN25、YN31~YN39、YJ1-19~YJ1-23、YJ1-47等计33个样品,占总样品数的33.3%。由于富集重金属的沉积物样品占的比例小,沉积物重金属EF值统计结果（图5）显示沅江入湖河床沉积物重金属富集不明显的特征。故对该沉积物重金属污染的评价应针对富集重金属的样品进行。
Fig. 6 Plots of component variable F1 to F2 of principal analysis of heavy metals in sediments from the inlet area of the lowermost Yuanjiang River

图6 沉积物样品重金属主成分分析主成分F1对F2投影图

5.3 沉积物重金属污染评价

5.3.1 地累积指数法 依据式（2）[30]计算沉积物重金属的污染地累积指数（Igeo）,计算公式为：
I ge o = lo g 2 [ C i ( K B i ) ] （2）
式中：Igeo 为地累积指数（Igeo ≤0,为无污染;0<Igeo ≤1,轻度污染;1<Igeo≤2,偏中度污染;2<Igeo≤3,中度污染;3<Igeo≤4,偏重污染;4<Igeo≤5,重污染;Igeo≥5,严重污 染[32]）;Ci是沉积物重金属i的含量;Bi为被评价重金属的环境背景值（取值参见前文）;K为地质特征引起背景值变动的校正系数,一般取为1.5。
上述富集重金属之离散样品（得分异常）的地累积指数评价结果统计如表2所示。可见,3个沉积柱中,底部（208~192 cm）沉积物存在轻度—中度Pb、Bi组合的重金属污染;中部（96~64 cm）沉积物存在轻度Pb、Mn、Cr、Ni、Cu组合的重金属污染;表浅部（64~0 cm）沉积物存在轻度—中度Pb、Mn、Cr、Ni、Cu、Zn、V、Bi组合的重金属污染,及重度的潜在Cd重金属污染。显示沅江入湖沉积物重金属污染在垂向上,自底部向浅部,重金属污染元素组合由单一的Pb-Bi污染,向Pb-Mn-Cr-Ni-Cu-Zn-Cd-V-Bi等多元素组合的复合污染转化,污染程度由轻度向重度污染变化。
Tab. 2 Statistic results of the Igeo values for heavy-metal enriched and synthetic enrichment index sediment samples from inlet area of the lowermost Yuanjiang River

表2 沅江入湖沉积物重金属地累积指数(Igeo)和综合富集指数(EI)统计结果

深度(cm) Pb Mn Cr Ni Cu Zn Cd V Tl Bi EI
64~0
(n=21)		 最小值 -0.11 0.19 0.00 0.09 -0.11 0.19 2.41 0.48 -0.55 -0.10 2.47
最大值 1.06 1.82 0.84 0.98 0.72 1.24 4.74 1.19 -0.04 1.19 6.93
平均值 0.45 0.99 0.34 0.35 0.22 0.66 3.46 0.72 -0.32 0.49 4.09
Cv 0.65 0.48 0.63 0.65 0.86 0.46 0.20 0.26 -0.45 0.72 0.31
96~64
(n=6)		 最小值 0.30 0.40 0.28 0.21 0.00 2.24
最大值 0.81 0.73 0.43 0.38 0.44 3.21
平均值 0.56 0.61 0.37 0.31 0.23 2.70
208~192
(n=6)		 最小值 0.26 -0.63 0.17 1.97
最大值 0.94 0.21 2.04 2.68
平均值 0.49 -0.37 0.71 2.31
5.3.2 综合富集指数法 尽管3个沉积柱中,重金属富集的沉积物样品数是YN>YJ>YW（表2）,但仍不能定性反映重金属污染的水平空间变化特点。为此,本文利用重金属综合富集指数（EI）来定量评价沉积物重金属污染总体特征。沉积物EI值的计算公式为[21]：
EI = ∑ i = 1 n C i B i / n （3）
式中：Ci为沉积物中重金属i的含量;Bi为相应重金属i的背景值;n为参评元素的个数。故评价元素的选取和背景值的确定会直接影响评价结果。由于重金属Tl虽然在沉积物中有富集,但污染并不明显（表2）,故不纳入EI值的计算。
富集指数EI值能定量反映沉积物中多种重金属综合污染状况。各重金属EI值计算时参考的背景值同EF和Igeo值的计算。垂直方向上,自深部至浅部沉积物EI值（平均）由 2.31、升高为4.09（表2）。与地累积指数评价结果相一致。浅表层（64~0 cm）沉积物重金属综合富集指数EI值变化范围自YN→YJ→YW依次为：2.0~4.75→2.39~4.08→2.0~3.33（n=8,9,5）。显示水平空间上自YN→YJ→YW,重金属污染趋于降低的变化特征。即沅江入湖沉积物重金属污染程度,自上游向下游有趋于降低的变化趋势。这种空间变化特征与YN沉积柱靠近常德市的空间分布相对应,反映人为活动对沉积物重金属污染的影响。值得进一步研究。

6 结论

对沅江入湖沉积物进行钻探取样,利用等离子质谱仪（ICP-MS）对沉积物重金属进行了分析,得出的结论如下：
（1）沅江下游入湖沉积物中,Ba、Sc、V、Th、U、Cu、Co、Ni、Cr等重金属的含量变化小,分布较均匀。而Mn、Zn、Pb、Mo、Cd、Tl、Bi等重金属的含量变化大,分布很不均匀,在部分沉积物中相对富集明显。
（2）沅江入湖沉积物重金属垂向变化特征显示,沉积物中存在中下部Pb、Tl、Bi富集层,中上部Pb、Cr、Ni、Cu富集层,浅表部V、Cr、Mn、Ni、Cu、Zn、Pb、Cd、Tl、Bi等多种重金属富集层,且沉积物中Cd达显著富集,Sc、V、Mn、Pb、Bi等达中等富集程度。
（3）沅江入湖沉积物重金属污染在垂向上自底部向浅部,重金属污染由Pb-Bi的单一元素组合向Pb-Mn-Cr-Ni-Cu-Zn-Cd-V-Bi等多元素组合的复合污染转化,污染程度由轻度向重度污染变化,且重金属污染程度自上游向下游趋于降低。这种重金属污染的空间变化规律可能与人为活动有关,值得进一步的研究。
致谢：感谢湖南师范大学资源与环境科学学院研究生王腾飞、王一志参加野外工作;感谢中国科学院广州地球化学研究所涂湘林副研究员帮助完成所有实验分析工作。

The authors have declared that no competing interests exist.

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DOI

[9]
熊建新, 彭保发, 陈端吕, 等. 洞庭湖区生态承载力时空演化特征. 地理研究, 2013, 32(11): 2031-2040.利用探索性空间数据分析以及百分位数和变异系数，基于Arc GIS 和Geo DA软件支撑，对洞庭湖区生态承载力的空间格局特征、空间关联特征和相对差异演变特征进行分析。结果表明：① 空间格局上，洞庭湖区生态承载力从西南向东北大体上呈现&ldquo;W&rdquo;型（较高&mdash;低&mdash;高&mdash;低&mdash;较高）空间格局，倒&ldquo;U&rdquo;型的县域差异特征显著。② 空间关联上，洞庭湖区生态承载力的分布呈正的全局空间自相关，出现相似县域之间的空间集聚，全局Moran&rsquo;s Ⅰ值相差不大，空间聚集程度比较稳定，趋于围绕某一偏低集聚度出现小范围内波动；局部空间自相关的LISA 集聚类型出现HH型、HL型和LH型3 种类型，依次集中分布在洞庭湖区的中部、西南部和东北部，局部空间格局保持相对稳定，但是聚类特征显现出稍微变化的迹象。③ 相对差异演变上，2001-2010 年洞庭湖区生态承载力相对差异演变整体上呈现一定的差异性。2001-2003 年相对差异较小，趋于稳定；2005 年前后相对差异较大；相比2001-2003 年，2005 年以来相对差异明显扩大且这种较大的空间相对差异随着时间的推移呈现小幅波动趋势。

DOI

[Xiong Jianxin, Peng Baofa, Chen Duanlv, et al.Temporal and spatial evolutionary feature of ecological carrying capacity in Dongting Lake region. Geographical Research, 2013, 32(11): 2031-2040.]

[10]
祝云龙, 姜加虎, 孙占东, 等. 洞庭湖沉积物中重金属污染特征与评价. 湖泊科学, 2008, 20(4): 477-485.于2003-2004年在洞庭湖湖区采集沉积物样品700个,测定了沉积物中As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的含量,并用地积累指数方法和主成分分析法对沉积物中的重金属污染状况进行了评价和分析.结果显示,洞庭湖各子湖区沉积物中Cd、Cr、Cu、Pb、zn的平均含量都属于国家土壤二级标准,AB、Hg、Ni属于国家土壤一级至二级土壤标准;在南洞庭湖与东洞庭湖人湖河流的三角洲的前缘是沉积物重金属积累最高的地点,而在西洞庭湖入湖河流三角洲的后缘沉积物重金属含量比前缘高.采用综合地积累指数法对洞庭湖各子湖区沉积物进行评价,结果表明:南洞庭湖(重污染)>东洞庭湖(偏重污染)>西洞庭湖(中度污染)>大通湖(中度污染)>城陵矶(轻度污染).采用主成分分析法对洞庭湖各子湖区沉积物进行分析,结果表明:南洞庭湖与东洞庭溯第一主成分贡献率分别为55.22%、56.86%,主要支配AS、Cd、Hg、Pb、zn的载荷,而第二主成分贡献率分别为30.04%、33.11%主要支配Cu、Cr、Ni的载荷:西洞庭湖、大通湖和城陵矶因沉积物重金属来源不同,主成分分析结果相差较大.

[Zhu Yunlong, Jiang Jiahu, Sun Zhandong, et al.Character and assessment of heavy metals in the sediments from Lake Dongting. Lake Sciences, 2008, 20(4): 477-485.]

[11]
姚志刚, 鲍征宇, 高璞. 洞庭湖沉积物重金属环境地球化学. 地球化学, 2006, 35(6): 629-638.对洞庭湖沉积物样进行了Cu、Pb、Zn、Cd、Cr、Ni、 As和Hg等8种元素含量分析.结果显示,洞庭湖沉积物中重金属污染物主要是Cd和Hg,其次是Pb、Zn、As和Cu;Cd平均含量达到 2.7mg/kg,是国家土壤环境质量三级标准(1.0mg/kg)的近3倍;Cu、Pb、Zn、As和Hg平均含量分别为51.3mg/kg、 52.8mg/kg、140mg/kg、22.5mg/kg和0.22mg/kg,均超过国家土壤环境质量一级标准.运用地累积指数法对其污染程度进行了 评价,认为重金属污染最严重的湖区是东洞庭湖的鹿角至城陵矶湖区(段),污染物可能主要来源于湘江流域;各子湖区(段)重金属综合污染状况评价结果是:东 洞庭湖＞大通湖＞横岭湖＞万子湖＞西洞庭湖＞采桑湖.入湖各河口区沉积物重金属含量与历史资料的对比表明,8种重金属含量均有较高程度的富集,反映近年来 洞庭湖流域内重金属污染有增加的趋势.

DOI

[Yao Zhigang, Bao Zhengyu, Gao Pu.The environmental geochemical characterization of heavy metals in sediment of Dongting Lake, Hunan. Geochemica, 2006, 35(6): 629-638.]

[12]
童霆. 洞庭湖的净化作用与微量元素资源. 中国地质, 1998, (10): 33-36.正洞庭湖是湘、资、沅、澧四水与长江的汇水盆地,是长江的调节湖泊。湖南省素有“有色金属之乡”的美称,滔滔“四水”所携带的矿质对长江是否构成污染?洞庭湖地区物产丰富,是重要的商品粮和渔业基地,其产品的环境质量如何?

[Tong Ting.The purification effect and trace element resources of Dongting Lake. Geology in China, 1998, (10): 33-36.]

[13]
申锐莉, 鲍征宇, 周旻, 等. 洞庭湖湖区水质时空演化(1983-2004). 湖泊科学, 2007, 19(6): 677-682.根据洞庭湖湖区的1983-2004年的水质监测数据,参照GB3838-2002中Ⅲ类水质标准,运用内梅罗水污染指数法进行水质评价,分析了洞庭湖湖区22年来的水质时空变化.结果表明:洞庭湖湖区水质污染在时间上呈有升有降的波动变化.洞庭湖湖区丰水期和洪水期的水质较差,但是从2002年以后,丰水期的水质逐渐好于平水期.污染空间变化表现为入湖河道的污染程度高于湖体,湖体污染呈西洞庭湖的污染较为严重,南洞庭湖其次,东洞庭湖的水质仍较好的格局.

[Shen Ruili, Bao Zhengyu, Zhou Min, et al.Spatial-temperoal evaluation of water quality of the Dongting Lake, China. Journal of Lake Sciences, 2007, 19(6): 677-682.]

[14]
祝云龙, 姜加虎, 黄群, 等. 大通湖及东洞庭湖区生物体重金属的水平及其生态评价. 湖泊科学, 2007, 19(6): 690-697.于2005年11月采集了大通湖及东洞庭湖区湖水和水生生物样品,并测定了水和水生生物样品中重金属(Cd、Pb、Hg、As)的含量,并对湖区生物体重金属进行了污染评价.研究结果表明,大通湖及东洞庭湖区湖水中重金属含量较小,绝大部分采样点水质都属于国家Ⅰ类水标准;水生生物体内CD、Pb含量为虾＞螺＞鱼,Hg的含量为鱼＞螺＞虾,As的含量为螺＞虾＞鱼;而鱼类重金属含量则为底栖鱼类＞中上层鱼类,肉食性鱼类＞植食性鱼类.大通湖及东洞庭湖区生物体中CD、Pb的污染指数为虾＞螺＞鱼,Hg的污染指数则为鱼＞螺＞虾,As的污染指数则为螺＞虾＞鱼.

[Zhu Yunlong, Jiang Jiahu, Huang Qun, et al.The heavy metal content in organisms at Lake Dongting and its ecological assessment. Journal of Lake Sciences, 2007, 19(6): 690-697.]

[15]
Zhong L, Liu L, Yang J.Characterization of heavy metal pollution in the paddy soils of Xiangyin county, Dongting lake drainage basin, central south China. Environmental Earth Sciences, 2012, 67(8): 2261-2268.The heavy metal accumulation in soils caused by industrialization has attracted broad attention. To evaluate the soil environmental quality of Xiangyin County, an important food production base in China, 99 top paddy soil samples were analyzed for total concentrations of As, Cd, Cr, Cu, Hg, Ni, Zn and Pb. Kriging interpolation was used to determine the spatial distribution of the metals. The assessment of soil environmental quality was performed according to pollution index methods. As the results showed, except for Cu, Cr and Ni, the mean concentrations of Zn, Pb, Cd, As and Hg in soils were elevated to different extents when compared with the background values. Moreover, except for Cd, contents of seven other elements in most soil samples were below the Class II criteria for Chinese environmental quality standards, which established the maximum allowable concentration of heavy metal in the farmland. Therefore, the soils were believed to be polluted mainly by Cd. All of the elements showed a similar spatial distribution pattern with low contents in the east upland area, and high contents in the middle by the west area, located close to Dongting lake. The long-term practice of using the Xiangjiang river as irrigation water was believed to be the main reason resulting in the enrichment of heavy metals in soils around Dongting lake. In addition, the evaluation results showed that about 45.8, 51.1 and 3.1 % of the study area were classified as slightly, moderately and seriously polluted with Cd, respectively. As for the other seven elements, soil environmental quality was fairly well because of their grades belonging to clean or excellent. By integration of the assessment results for individual elements, it was found that about 3.8 % of the study area was clean, 82.2 % was slightly polluted and 14.1 % was moderately polluted. On the whole, most of the study area was at safe and guarded level. However, appropriate measures still should be adopted to control the levels of heavy metals in agricultural soils. The findings obtained in this study were useful for establishing policies for protecting the local soil environments and guaranteeing the food quality as well as the people's health.

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[16]
钱杏珍, 李岫霞. 洞庭湖水系沉积物的地球化学背景值. 科学通报, 1988, 33(6): 458-462.<正> 洞庭湖水系主要有湘江、资水、沅江和澧水组成,位于东经1070°—114°,北纬24°—30°之间。流域面积为27000km~2主要在湖南省内,约有92％的流域地区是由沉积岩组成,其余8％的地区以火成岩为主。本水系属于中亚热带季风气候区,热量丰富,冷热明显;雨量充沛,分布不匀。研究沉积物的地球化学背景值可为研究水系的元素分布和分配以及迁移转化提供重要的依据,也为判断水系水体遭受污染程度及评价水环境质量提供科学依据。

[Qian Xingzhen, Li Youxia.Geochemical background values of elements in sediments of Dongting Lake Watershed. Chinese Science Bulletin, 1988, 33(6): 458-462.]

[17]
Peng B, Tang X Y, Yu C X, et al.Geochemistry of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan province (P. R. China): Implications on sources of trace metals. Environmental Earth Sciences, 2011, 64(5): 1455-1473.This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The results show that trace metals Cd, Bi, Sn, Sc, Cr, Mn, Co, Ni, Cu, Zn, Sb, Pb and Tl are enriched in the sediments. Among these metals, Cd, Bi and Sn are extremely highly enriched (EF values > 40), metals Zn, Sn, Sb and Pb significantly highly (5 < EF < 20), and metals Sc, Cr, Mn, Co, Ni, Cu and Tl moderately highly (2 < EF < 5) enriched in the river sediments. All these metals, however, are moderately enriched in the lake sediments. Geochemical results of trace metals Th, Sc, Co, Cr, Zr, Hf and La, and Pb isotopes suggest that metals in the river sediments are of multi-sources, including both natural and anthropogenic sources. Metals of the natural sources might be contributed mostly from weathering of the Indosinian granites (GR) and Palaeozoic sandstones (PL), and metals of anthropogenic sources were contributed from Pb-Zn ore deposits distributed in upper river areas. Metals in the lake sediments consist of the anthropogenic proportions, which were contributed from automobile exhausts and coal dusts. Thus, heavy-metal contamination for the river sediments is attributed to the exploitation and utilization (e.g., mining, smelting, and refining) of Pb-Zn ore mineral resources in the upper river areas, and this for the lake sediments was caused by automobile exhausts and coal combustion. Metals Bi, Cd, Pb, Sn and Sb have anthropogenic proportion of higher than 90%, with natural contribution less than 10%. Metals Mn and Zn consist of anthropogenic proportion of 60-85%, with natural proportion higher than 15%. Metals Sc, Cr, Co, Cu, Tl, Th, U and Ta have anthropogenic proportion of 30-70%, with natural contribution higher than 30%. Metals Ba, V and Mo might be contributed mostly from natural process.

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[18]
Sun G X, Wang X J, Hu Q H.Using stable lead isotopes to trace heavy metal contamination sources in sediments of Xiangjiang and Lishui rivers in China. Environental Pollution, 2011, 159(12): 3406-3410.Lead isotopes and heavy metal concentrations were measured in two sediment cores sampled in estuaries of Xiangjiang and Lishui Rivers in Hunan province, China. The presence of anthropogenic contribution was observed in both sediments, especially in Xiangjiang sediment. In the Xiangjiang sediment, the lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratio, than natural Pb isotope signature (1.198 and 2.075 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively), indicated a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and high (208)Pb/(206)Pb. The corresponding concentrations of heavy metals (As, Cd, Zn, Mn and Pb) were much higher than natural values, suggesting the contaminations of heavy metals from extensive ore-mining activities in the region.

DOI PMID

[19]
Sun W, Sang L, Zhang B.Trace metals in sediments and aquatic plants from the Xiangjiang River, China. Journal of Soils & Sediments, 2012, 12(10): 1649-1657.PurposeThe metal concentrations and Pb isotopic composition in sediments and plants from the Xiangjiang River, China, were investigated to understand the contamination and potential toxicity of metals in sediments; to determine the accumulation and distribution of metals in plant tissues; and to trace the possible pollution source of Pb in sediments and plants.Materials and methodsSediments and plants were collected from 43 sampling sites in the study region. After sediments were air-dried and passed through a 63-渭m sieve, they were acid-digested and DTPA-extracted for determination of total and bioavailable metals. The plants were separated into roots, leaves, and stems; dried; cut into pieces; and digested with HNO

DOI

[20]
毛美洲, 刘子慧, 魏金玺. 湘江表层底泥中重金属化学形态的研究. 环境科学, 1981, 2(5): 35-41.正 前言 迄今为止,人们常以江湖河海水体沉积物中重金属的总量作为调查、评价重金属在沉积物环境中的含量水平和分布规律,并据此来推断水体的污染类型和状况,对重金属在沉积物中的形态和其相互转化的研究还不多。这样,有时就会得出一些不符合实际情况的结论。水中的重金属离子在一定条件下,由于离子交换、共沉淀,吸附、水解、络合、絮凝等理化作用,最终极大部分进入沉积物,而在条件变化时,又有一部分重金属由于扩

[Mao Meizhou, Liu Zihui, Wei Jinxi.Study on heavy metal chemical type in bottom mud of Xiangjiang upper area. Environmental Science, 1981, 2(5): 35-41.]

[21]
鲍志诚, 彭渤, 徐婧喆, 等. 湘江入湖河床沉积物主量元素地球化学特征及其对重金属污染的指示. 地球化学, 2012, 41(6): 545-558.本次工作利用X射线荧光(XRF)和电感耦合等离子质谱(ICP-MS)分析技术,对湘江入湖河段沉积物进行主元素和重金属元素分析。结果表明,湘江入湖沉积物中主元素含量变化相对稳定,沉积物具有明显亏CaO、Na2O,而富MnO、Al2O3的化学组成特征。其化学组成和风化蚀变特征(蚀变指数CIA值大于78)指示流域上游花岗岩为沉积物提供了主要的物源。主元素揭示的沉积物矿物组成主要包括Al2O3表征的细粒黏土矿物类和SiO2、Na2O表征的粗粒碎屑矿物类两部分。沉积物中重金属元素含量变化大,重金属综合富集指数EI值自湾河wH(EI=4.7、14.2)向湘阴XY(6.6、5.6)再向屈原农场QN沉积柱(18.4)趋于增大,重金属污染程度自上游向下游趋于增强。重金属污染程序主要与以Al2O3为代表的Ⅰ类元素呈正相关关系。预示重金属污染主要与黏土矿物、铁锰氧化物、有机质、及磷灰石等副矿物相关。其中Bi、Pb、Mn、Tl等重金属污染更趋于在黏土矿物、铁锰氧化物、有机质等矿物相中增强,Cd污染可能主要与铁锰氧化物、有机质等有关,U污染则主要与铁氧化物矿物有关,而Cu、Sb污染主要与有机质关系密切。不同的矿物相可能引起不同种类的重金属污染。

DOI

[Bao Zhicheng, Peng Bo, Xu Jingzhe, et al.Geochemical study on the relation of chemical compositions to heavy metal contamination of sediments from the lowermost Xiangjiang River, Hunan Province, China. Geochemica, 2012, 41(6): 545-558.]

[22]
杨奎锋, 杨坤光, 马昌前. 雪峰山安化—溆浦断裂带变形特征及ESR定年. 大地构造与成矿学, 2004, 28(3): 263-269.安化—溆浦断裂是雪峰山西部一条重要的区域性断裂带。宏观上呈向NW突出的弧形 ,由数条从溆浦向南撒开的主断裂及其次级分支断层组成。显微构造、断层岩与石英脉流体包裹体均一温度 (集中在 16 0℃附近 )均显示 ,断裂带以浅层脆性变形为主 ,最深动力变质岩仅为糜棱岩化绢云母千枚岩。断层岩中石英脉ESR(电子自旋共振 )定年显示 ,断裂在燕山期 (15 6 .9～ 136 .2Ma ,119.8～ 90 .6Ma)热流体活动强烈 ;而发育在上述两个时间段内的石英脉 ,不论在野外产状、显微构造及流体包裹体均一温度上都存在明显的差异 ,由此初步推断 ,这两个时间段之间应是雪峰山中生代挤压与伸展运动的反转时期。

DOI

[Yang Kuifeng, Yang Kunguang, Ma Changqian.Deformation characteristics and esrdating of Anhua-Xupu fault belt in the Xuefeng mountains, Hunan. Geotectonica et Metallogenia, 2004, 28(3): 263-269.]

[23]
彭渤, 陈广浩, Adam Piestrzynski.湘西沃溪钨锑金矿床辉锑矿脉矿物学特征及其矿床成因指示. 矿物学报, 2003, 23(1): 82-90.辉锑矿脉为沃溪钨锑金矿床最具工业价值的矿石类型.本文报道了近 期对该型矿石的主要矿石矿物如自然金、自然锑、辉锑矿、白钨矿、黑钨矿等的观察研究和电子探针分析结果.分析了矿石矿物微量化学成分特征及其所揭示的矿床 成因信息.研究表明,矿床成矿应与区域构造-岩浆作用有成因联系.从而建立了该矿床新的成矿机理模式.

DOI

[Peng Bo, Chen Guanghao, Adam Piestrzynski.Ore mineralogy of stibnite ore-veins and its genetic implications for the W-Sb-Au ore deposit at Woxi, Western Hunan, China. Acta Mineralogica Sinica, 2003, 23(1): 82-90.]

[24]
彭渤, Robert Frei, 涂湘林. 湘西沃溪W-Sb-Au矿床白钨矿Nd-Sr-Pb同位素对成矿流体的示踪. 地质学报, 2006, 80(4): 561-570.本文对湘西沃溪W-Sb-Au矿床白钨矿进行了系统的Nd-Sr-Pb同位素分析。结果表明,白钨矿的Sm、Nd含量较低,147Sm/144Nd(0.64~1.27)值和Sm/Nd值(1.11~2.22)变化较大,其εNd(t=199Ma)值也很低,平均为-25.5(n=9);白钨矿的87Sr/86Sr值(0.7476~0.7504)高,平均为0.74961(n=11),代表白钨矿形成时的初始87Sr/86Sr(t=199Ma)值;逐级分离Pb同位素分析结果显示白钨矿的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb值变化范围小,平均依次分别为18.11、15.61、38.6,与含金石英脉中黄铁矿、蚀变围岩及区域板溪群板岩等的相应Pb同位素比值基本一致。白钨矿Nd-Sr-Pb同位素组成和闪锌矿等其他矿物的Sr同位素特征指示成矿流体来自板溪群下伏成熟陆壳、深部花岗质岩浆、浅部赋矿围岩等源区。成矿流体是这些来自不同源区的流体相作用而形成的混合流体。成矿作用则是这些不同源区的流体混合作用并演化的结果。且成矿流体演化早期是来自下伏成熟陆壳的流体与来自赋矿围岩的流体混合,导致早期W成矿;晚期是来自深部花岗质岩浆的流体与浅部赋矿围岩的流体混合作用,导致晚期Sb-Au成矿。W-Sb-Au成矿则是中生代陆内碰撞造山体制下不同期次的流体演化和叠加作用的结果。

[Peng Bo, Robert Frei, Tu Xianglin.Nd-Sr-Pb isotopic geochemistry of scheelite from the Woxi W-Sb-Au Deposit, Western Hunan: Implications for sources and evolution of Ore-forming fluids. Acta Geologica Sinica, 2006, 80(4): 561-570.]

[25]
刘颖, 刘海臣, 李献华. 用ICP-MS准确测定岩石样品中的40余种微量元素. 地球化学, 1996, 25(6): 552-558.本文建立了一种用ＨＦ＋ＨＮＯ３密封溶解样品，以ＵＳＧＳ标准岩石样品ＢＣＲ－１作参考标准，外加质量监控样品测定岩石样品中微量元素的ＩＣＰ－ＭＳ分析方法。该方法具有简单，准确，测定元素多的特点。用该方法对ＵＳＧＳ和ＡＧＳＯ的标准岩石样品中４０余种微量元素进行测定，结果表明，除个别元素的分析结果与推荐值偏差接近或略大于１０％外，绝大多数元素的分析结果与推荐值偏差在５％以内。

[Liu Ying, Liu Haichen, Li Xianhua.Simultaneous and precise determination of 40 trace element in rock samples using ICP-MS. Geochimica, 1996, 25(6): 552-558.]

[26]
霍亚贞, 李天杰. 土壤地理实验实习(2版). 北京: 高等教育出版社, 1985.

[Huo Yazhen, Li Tianjie.Laboratory Introduction of Physical Geography of Soils (second edition). Beijing: High Education Press, 1985.]

[27]
Sutherland R A.Bed sediment-associated trace elements in an urban stream, Oahu, Hawaii. Environmental Geology, 2000, 39(6): 611-627.<a name="Abs1"></a>&#8194;Of the 117 stream and lake systems sampled nationwide, fish from Manoa Stream on Oahu, Hawaii, have consistently shown the highest Pb concentrations. Therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5.8-km stretch of Manoa Stream. A total of 123 samples (&lt;63&#8201;&#956;m) were examined for 18 elements and 14 samples for 21 elements. Selected samples were also examined using different leach solutions to examine metal phase associations. All trace metal data, computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for Cr and Ni; minor anthropogenic contamination for Ba, Cd, Cu, Hg and Zn; and a very strong contamination signal for Pb. Maximum Pb contents (up to 1080&#8201;mg kg<sup>&#8722;1</sup>) were associated with anthropogenic material dumping in minor tributaries, storm sewer sediments and sediments in the &#8220;lower&#8221; section of the basin. Proportionally Pb had the highest non-residual component of elements examined; dominantly in the reducible phase associated with Mn and amorphous Fe oxyhydroxides. The contamination signal was typically lowest in the &#8220;undisturbed&#8221; headwater reach of the basin (above 5.1&#8201;km) with significant increases throughout the &#8220;residential&#8221; and &#8220;commercial-institutional&#8221; zones of the mid-basin. The spatial pattern of bed sediment contamination and evidence from storm sewer-outlet sediments strongly indicates that Pb, and to a lesser degree some other metals, is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments. The primary source of sediment-associated metals is considered to be the automobile, though other minor sources can not be ruled out.

DOI

[28]
Kareem K, Diana M F, Lina A H, et al.Trace metals in topsoils near the babylon cement factory (Euphrates River) and human health risk assessment. Environmental Earth Sciences, 2015, 74(1): 665-673.Metals were studied in topsoils surrounding a cement plant near the Euphrates River, Iraq. Bulk concentrations of SiO 2 , Al 2 O 3 , CaO, MgO, Na 2 O, K 2 O, Fe, Ni, Cu, Zn, Cd, Pb, pH, organic matter, clay, sand, and silt were analyzed. The results indicate that the soils in the area are primarily alkaline with an average pH of 8.8; the texture is sandy loam. The CaO percentages were found to be high (31.9wt% average). Soil levels of Pb, Zn, and Cd levels close to the cement plant are higher than the values reported in the literature. An enrichment factor calculation suggests that Ni, Cu, Zn Cd, and Pb have anthropogenic sources and exhibit a significant level of contamination. Principal component analysis identified Pb, CaO, Zn, and Cd as the signature geochemical characteristics that are associated with the cement factory. Moreover, most of the affected soils exhibit a NWE trend, which coincides with the prevailing winds in the study area. This pattern is indicative of dry deposition as the primary mechanism for metal accumulation. The hazard index (HI Ni-Zn-Cdb ) was found to be 0.619 for cumulative metals, representing the highest value reported for health risk related to impacted soils by cement industry.

DOI

[29]
唐晓燕, 彭渤, 余昌训, 等. 湖南安化下寒武统黑色页岩土壤元素地球化学特征. 环境科学学报, 2009, 29(12): 2623-2634.本研究对湖南安化县东坪、烟溪两地发育于下寒武统黑色页岩上的6个土壤剖面进行系统采样,并利用ICP-MS等分析技术对土壤和相应岩石样品的主量元素和微量元素(包括重金属和稀土元素)含量进行了分析.主量元素A-CN-K(Al<sub>2</sub>O<sub>3</sub>-CaO+Na<sub>2</sub>O-K<sub>2</sub>O)图解显示,黑色页岩土壤的形成是黑色页岩化学风化的结果,经历了早期的Ca、Na淋失和后期的Al、Fe富集过程后,土壤具有贫Ca、Na而富Al、Fe的化学组成特征.多因子分析和相关性分析结果表明,成土过程中,微量元素可分为稳定元素(Ti、Zr、Nb、Hf、Ta、W等)、次稳定元素(Be、Sc、Ga、Ge、Rb、Cs、Pb、Th、Ba等)、活动性较强的元素(REE、Y、P、Sn等)和强活动性元素(Mn、Co、Ni、Zn、Cd、Tl、V、Mo、Sb、U等).富集因子重金属污染评价显示,V、U仅在烟溪土壤剖面达到显著污染程度,Sn、Ba在东坪土壤剖面达到显著污染.Mo、Cd、Sb等重金属则在东坪和烟溪土壤均达到显著污染程度,其中,Cd在东坪可达到高度污染水平,而Mo在烟溪可达到极度污染水平.微量元素及稀土元素地球化学示踪分析显示,黑色页岩土壤没有受到外来物源的干扰,土壤重金属污染为来自黑色页岩的自然污染源.

[Tang Xiaoyan, Peng Bo, Yu Changxun, et al.Elemental geochemistry of soils derived from the Lower-Cambrian black shales in Anhua county, central Hunan (China). Acta Scientiae Circumstantiea, 2009, 29(12): 2623-2634.]

[30]
Muller G.Index of geoaccumulation in sediments of the Rhine River. Geojournal, 1969, 2(3): 108-118.

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