pH and Eh Variations and the DREEs Contents of a Small Watershed in South Jiangxi Province
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摘要:
测试流经稀土矿区河水的pH和Eh值, 可以反映矿区的酸碱性、氧化还原环境。本文以赣南地区濂水、桃江、东江流域为研究对象, 利用ICP-MS和三通道多参数测试仪分别测试水样中溶解态稀土含量(DREEs)和pH、Eh值, 分析pH、Eh值的变化特征以及DREEs含量与pH值的相关性。结果表明:① 研究区水体中DREEs含量变化较大, 介于几μg/L至几十mg/L之间; DREEs经球粒陨石标准化后表现为弱的轻稀土富集模式, Eu、Ce显示负异常; ② 溶解态稀土及La含量分别与pH值呈弱的负相关性, 说明地表水体中DREEs浓度及分布模式在一定程度上受外部环境酸碱性的影响; ③ 对于流经地层、地层内离子吸附型稀土矿区的水样, 其pH均值分别为7.40、6.94, Eh均值分别为-0.023 V、6.55 mV; 对于流经岩体、风化壳离子吸附型稀土矿区的水样, 其pH均值分别为6.61、4.37, Eh均值分别为0.024 V、0.15 V, 表明赣南地区离子吸附型稀土矿区处于中酸性的氧化环境。
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关键词:
- 赣南小流域 /
- 溶解性稀土 /
- 电感耦合等离子体质谱法 /
- pH值 /
- Eh值
Abstract:Knowing the pH and Eh values of stream water flowing through the rare earth element deposits can lead to an understanding of the acidity and alkalinity and oxidation-reduction environment of deposits. For this purpose, the Lianshui, Taojiang and Dongjiang rivers in south Jiangxi were selected for study. The dissolved rare earth elements (DREEs) and pH-Eh values of water samples were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Three-channel Multi-parameter, respectively. Conclusions are listed as follows: (1) DREEs contents range widely from several μg/L to tens of mg/L, and chondrite-normalized DREEs patterns show a slightly right-inclined trend with Eu and Ce negative anomalies. (2) The weakly negative correlations of DREEs and La contents with pH values indicate that the DREEs contents in water and distribution patterns are affected by the pH values of external environment. (3) Stream water samples flowing through stratums and ion-adsorbed type REE deposits in stratums have pH values of 7.40 and 6.94, respectively, and Eh values of -0.023 V and 6.55 mV, respectively, whereas stream water flowing through granite plutons or weathering crust ion-adsorbed type REE deposits have respective pH values of 6.61 and 4.37, and respective Eh values of 0.024 V and 0.15 V. It indicates that ion-adsorbed type REE deposits formed in a neutral-acid or acid oxidized environment.
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图 2 水样中溶解态稀土球粒陨石标准化曲线(标准化数据引自文献[16])以及DREEs含量与pH值相关性图解
Figure 2.
表 1 桃江、濂水、东江部分采样点河水中溶解态稀土元素的含量
Table 1. Contents of DREEs in part of water samples of Taojing, Lianshui and Dongjiang Rivers
稀土元素特征 AY2 XW5 XW6 LN2 XW16 AY9 AY10 AY4 AY5 AY7 AY8 AY11 XW7 XW17 AY-X1 LN6 ΣREEs(mg/L) 0.688 0.213 0.180 0.068 1.622 0.022 0.038 8.373 0.028 1.020 78.219 0.039 3.276 87.723 0.120 48.827 LREEs(mg/L) 0.184 0.157 0.102 0.011 1.310 0.008 0.020 2.546 0.011 0.558 47.967 0.021 2.233 63.575 0.065 5.595 HREEs(mg/L) 0.503 0.056 0.078 0.056 0.313 0.013 0.017 5.827 0.017 0.462 30.252 0.018 1.043 24.148 0.055 43.232 LREEs/HREEs 0.367 2.798 1.303 0.201 4.185 0.626 1.180 0.437 0.622 1.208 1.586 1.171 2.142 2.633 1.179 0.129 δEu 0.042 0.291 0.410 0.239 0.319 0.457 0.615 0.036 0.380 0.426 0.589 0.450 0.261 0.359 0.545 0.014 δCe 0.235 0.188 0.093 0.058 0.152 0.064 0.020 0.226 0.090 0.086 0.017 0.056 0.269 0.167 0.020 0.130 注:其余点位水样的溶解态稀土含量低于检出限。 表 2 各水样点的温度、pH、Eh等参数值
Table 2. Temperature, pH, Eh parameters of each water samples
取样位置样品号1
(原水)样品号2
(原水)样品号3
(滤水)温度 pH Eh(mV) 水系 岩体 矿区/地层 岩体(B区) AY3-W1 AY3-W2 AY3 26.3 6.617 25.9 濂水 岩体 - AY4-W1 AY4-W2 AY4 21.7 4.424 151.6 濂水 岩体 - AY5-W1 AY5-W2 AY5 25.4 7.323 -21.1 濂水 岩体 - AY6-W1 AY6-W2 AY6 21.5 7.092 -1.8 濂水 岩体 - AY7-W1 AY7-W2 AY7 22.2 6.934 2.0 濂水 岩体 - AY8-W1 AY8-W2 AY8 23.7 5.845 68.3 濂水 岩体 - AY11-W1 AY11-W2 AY11 20.1 7.110 -5.4 濂水 岩体 - AY12-W1 AY12-W2 AY12 23.6 7.449 -24.3 濂水 岩体 - XW1-W1 XW1-W2 XW1 23.7 7.230 -15.5 东江 岩体 - XW7-W1 XW7-W2 XW7 18.7 5.590 88.4 东江 岩体 - XW8-W1 XW8-W2 XW8 23.1 7.136 -4.2 东江 岩体 - 地层内矿区
(A’区)AY9-W1 AY9-W2 AY9 21.4 7.146 -1.1 濂水 - REEs/Z AY10-W1 AY10-W2 AY10 23.9 6.730 14.2 濂水 - REEs/Z 岩体内矿区
(B’区)AY-X1-W1 AY-X1-W2 AY-X1 23.4 7.503 -33.3 濂水 岩体 REEs LN6-W1 LN6-W2 LN6 24.6 4.372 154.6 桃江 岩体 HREEs XW17-W1 XW17-W2 XW17 21.4 2.610 257.6 东江 岩体 LREEs 地层(A区) LN1-W1 LN1-W2 LN1 22.4 7.713 -42.3 桃江 - J LN2-W1 LN2-W2 LN2 24.6 7.169 -8.6 桃江 - K LN3-W1 LN3-W2 LN3 23.2 7.635 -38.5 桃江 - Q LN4-W1 LN4-W2 LN4 26.3 7.744 -44.2 桃江 - Q LN5-W1 LN5-W2 LN5 22.6 7.719 -41.9 桃江 - Q LN7-W1 LN7-W2 LN7 22.9 8.003 -59.6 桃江 - Q LN8-W1 LN8-W2 LN8 22.9 7.637 -36.3 桃江 - J LN9-W1 LN9-W2 LN9 21.1 7.995 -52.4 桃江 - J LN10-W1 LN10-W2 LN10 25.3 6.915 9.5 桃江 - Q AY1-W1 AY1-W2 AY1 25.5 7.025 -5.5 濂水 - K AY2-W1 AY2-W2 AY2 23 5.592 84.2 濂水 - K XW3-W1 XW3-W2 XW3 24.4 7.505 -31.4 东江 - - XW4-W1 XW4-W2 XW4 24.8 7.549 -38.0 东江 - - XW5-W1 XW5-W2 XW5 25.7 7.104 -8.0 东江 - - XW6-W1 XW6-W2 XW6 24.6 7.099 -0.8 东江 - - XW9-W1 XW9-W2 XW9 20.3 7.098 7.3 东江 - Z XW16-W1 XW16-W2 XW16 24.6 8.365 -80.5 东江 - - 注:Z—震旦系,J—侏罗系,K—白垩系,Q—第四系,LREEs—轻稀土元素,HREEs—重稀土元素;对于AY-X1-W1及XW17-W1采样点水样,其pH、Eh值受采矿工作的影响不能代表原始矿区情况,作图及讨论时未计入。 -
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