On the composition of rare earth elements of suspended substance in lower reach of the Yangtze River and main rivers in Zhejiang Province in dry season
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摘要:
基于2021年 10月至11月在长江下游及钱塘江、椒江和瓯江等浙江主要河流枯水期采集的64个悬浮物样品，分析研究了其粒度分布和稀土元素（REE）组成，讨论了各河悬浮物REE组成差异以及物源端元特征。结果显示，枯水期长江下游、钱塘江、椒江和瓯江悬浮物REE含量均值分别为209.52、173.64、211.86和228.70 mg/kg；北美页岩（NASC）标准化配分曲线明显向右倾，并有明显的Ce负异常特征。与前人所测数据相比，钱塘江和瓯江悬浮物REE含量明显较高；长江悬浮物REE和前人长江悬浮物/沉积物表现总体一致。从(La/Yb)NASC—(La/Gd)NASC图看，长江、钱塘江、椒江、瓯江之间有一定差别，可成为它们物源端元的判别指标；相对于历史沉积物数据，长江悬浮物REE比值分布范围较为集中，以悬浮物为对象研究河流物源端元比沉积物有更好的效果。
Abstract:Sixty-four samples of suspended substance were collected in October–November, 2021 from the lower reaches of Yangtze River and major rivers in Zhejiang Province in dry season, from which the differences of distribution characteristics of rare earth elements (REEs) and provenance indication of the suspended substance were discussed. Results show that the average REE contents in the suspended substance from the lower reaches of the Yangtze River, Qiantang River, Jiaojiang River, and Oujiang River in dry season were about 209.52, 173.64, 211.86, and 228.70 mg/kg, respectively, and the contents of REEs of the Qiantang River and the Oujiang River were obviously higher than previous data. The normalized partition curve against the value of North American Shale Composition (NASC) was gentle in general and slightly incline to the right, with obvious MREE enrichment, which is consistent in overall with the previous studies of the Yangtze River and major rivers in Zhejiang Province. The diagrams of (La/Yb)NASC vs (La/G)NASC, the index of (La/Yb)NASC, and (La/Gd)NASC were used to distinguish provenance of the Yangtze River from rivers in Zhejiang Province. The distribution scope of (La/Yb)NASC and (La/Gd)NASC of suspended substance of this study is more concentrated than those of the historical data, which mean that suspended substance could be used for river provenance study.
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图 1 研究区和悬浮物样品采样位置示意图
Figure 1. Schematic diagram of the study area and sampling locations
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图 2 研究区河流悬浮物粒度组成三角图
Figure 2. Particle size composition of suspended sediments of the study rivers
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图 3 研究区河流悬浮物稀土元素特征参数
Figure 3. Characteristic parameters of REE of suspended sediments in the study rivers
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图 4 研究河流悬浮物稀土元素配分模式
Figure 4. Chondrite-normalized patterns of rare earth elements in suspended sediments of the study rivers
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图 5 长江悬浮体REE标准化配分模式与前人研究对比
数据来源：长江下游（南京-崇明岛）、长江下游（大通、徐六泾）、长江下游（江苏-崇明岛）和长江中下游（武汉-上海）数据分别来自文献[13,15,17,47]，长江下游0404、长江下游0507、长江下游0707数据来自文献[35]；湘江和赣江沉积物数据来自文献[21,48]。
Figure 5. NASC-normalized REE patterns of suspended substance of Changjiang River and the comparison to those from previous studies
Data source: data of the lower reaches of Changjiang River: Datong, Xuliujing, Nanjing-Chongming Island, Jiangsu-Chongming Island, and the mid-lower reaches of Changjiang River: Wuhan-Shanghai are from references [13,15,17,47]. Data of the lower reaches of Changjiang River: 0404, 0507, 0707 are from reference [35]. Data of the Xiangjiang River and the Ganjiang River are from references [21,48].
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图 6 浙江河流悬浮体REE配分模式与前人研究对比
数据来源：钱塘江-A和瓯江-A悬浮物数据来自文献[34]，瓯江-B沉积物数据来自文献[45]，钱塘江-C和瓯江-C沉积物数据来自文献[49]。
Figure 6. Comparison of NASC-normalized patterns of REE in this study and previous studies
Data source: data of the Qiantangjiang-A and Oujiang-A are from reference [34]; Data of the Oujiang-B are from reference [45]; Data of Qiantangjiang-C and Oujiang-C are from reference [49].
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图 7 长江与浙江河流悬浮体REE配分模式比较
Figure 7. Comparison of NASC-normalized patterns of REE between the Changjiang River and main rivers in Zhejiang Province
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图 8 NASC标准化典型元素比值图
数据来源：UCC数据来自文献[38]，长江下游（南京-崇明岛）、长江下游（大通、徐六泾）、长江下游（江苏-崇明岛）和长江中下游（武汉-上海）数据分别来自文献[13, 15,17,47]，长江下游0404、长江下游0507、长江下游0707数据来自文献[35]；湘江悬浮物数据来自文献[50]，湘江和赣江沉积物数据来自文献[21,48]。
Figure 8. The NASC-normalized typical parameters of REEs
Data sources: UCC data are from reference [38]; the lower reaches of Changjiang River: Datong, Xuliujing, Nanjing-Chongming, and Jiangsu–Chongming Island; and the mid-lower reaches of Changjiang River: Wuhan–Shanghai are from references [13, 15,17,47]; lower reached of Changjiang River: 0404, 0507, 0707 are from reference [35]; suspended substance of the Xiangjiang River are from reference [50]; sediments of Xiangjiang River and Ganjiang River are from references [21,48].
Table 1 Hydrological parameters of the Yangtze and main rivers in Zhejiang Province
河流 河口位置 长度/km 流域面积
/103km2径流量
/(km3/a)输沙量
/(Mt/a)长江 东海 6300 1705.4 898.3 35100 钱塘江 杭州湾 688 24.3 21.8 275 椒江 台州湾 206 5.71 6.7 840 瓯江 温州湾 388 18.0 14.4 232 
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表 2 标样（GBW 07316）测试值与推荐值的偏差
Table 2 Deviation between test value and recommended value of the reference (GBW 07316)
% 标样 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu A −4.36 −2.73 −3.71 −4.66 −3.26 12.11 4.10 0.90 7.10 −2.45 6.16 −6.58 5.83 −7.88 B −2.54 −0.03 −0.14 −2.94 −0.94 14.33 4.80 1.26 6.75 −1.52 7.70 −6.46 8.36 −5.80 C 0.29 0.01 0.93 −4.57 −2.31 14.27 9.77 7.02 3.70 −5.48 3.04 −11.09 −3.26 −7.35
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表 3 研究区悬浮物粒径特征
Table 3 Particle size characteristics of suspended matter in the study rivers
河流 中值粒径/ϕ 分选系数
平均值偏态
平均值峰态
平均值平均值 最大值 最小值 长江 6.00 7.65 2.95 2.10 0.51 2.58 钱塘江 5.85 7.83 2.29 2.18 0.48 2.58 椒江 7.13 7.98 5.85 1.52 0.65 3.05 瓯江 7.35 7.84 6.64 1.40 0.56 2.92
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表 4 研究区河流悬浮物稀土元素主要参数特征
Table 4 Main characteristics of REE of suspended substance in study rivers
河流 指标 ∑REE/(mg/kg) LREE/(mg/kg) HREE/(mg/kg) LREE/HREE (La/Yb)N (La/Gd)N δCe δEu 长江 平均值 209.52 193.71 15.81 12.33 1.10 0.82 0.94 0.6 标准偏差 19.22 17.74 2.22 0.91 0.05 0.04 0.08 0.02 变化系数/% 9.17 9.16 14.07 7.35 2.76 4.31 8.34 2.79 钱塘江 平均值 173.64 159.23 14.36 11.09 0.98 0.74 1 0.59 标准偏差 15.59 14.32 1.31 0.33 0.05 0.01 0.04 0.02 变化系数/% 8.98 8.99 9.15 2.94 5.43 1.42 4.47 2.61 椒江 平均值 211.86 195.94 15.93 12.3 0.07 0.81 1.01 0.56 标准偏差 12.14 11.39 0.81 0.27 0.42 0.05 0.04 0.01 变化系数/% 5.73 5.81 5.08 2.17 4.99 6.48 3.77 2.14 瓯江 平均值 228.7 220.23 17.47 12.59 1.13 0.82 1.05 0.53 标准偏差 27.05 25.3 1.76 0.21 0.03 0.01 0.02 0.02 变化系数/% 11.38 11.49 10.07 1.7 2.98 1.35 2.1 3.57
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表 5 长江各数据集稀土元素分布指数
Table 5 Distribution range of REE in different data sets of the Yangtze River
数据集 分布指数 站位数 悬浮物-本研究 0.050 39 悬浮物-0404 0.271 17 悬浮物-0507 0.104 24 悬浮物-0707 0.234 25 湘江沉积物 0.503 16 沉积物（武汉-上海） 0.308 13 沉积物（崇明岛-江苏） 0.104 10 沉积物（大通、徐六泾） 0.018 6 注：分布指数 = (La/Gd)NASC分布范围 × (La/Yb)NASC分布范围。数据来源同图8。
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