地下水系统中砷活化的钼同位素地球化学指示

李梦娣; 周炼; 王焰新; 吴潇; 王帅

doi:10.3799/dqkx.2014.010

地下水系统中砷活化的钼同位素地球化学指示

doi: 10.3799/dqkx.2014.010

李梦娣^1,,
周炼²,
王焰新^1, ,,
吴潇¹,
王帅¹

1.
中国地质大学生物地质与环境地质国家重点实验室, 湖北武汉 430074
2.
中国地质大学地质过程与矿产资源国家重点实验室, 湖北武汉 430074

基金项目:

国家自然科学基金 40830748

国家自然科学基金 41120124003

科技部"863"计划课题 2012AA062602

详细信息

作者简介:
李梦娣(1986-), 女, 博士, 主要从事地下水防治与污染及同位素地球化学研究.E-mail: limengdi1028@163.com

通讯作者:
王焰新, E-mail: yx.wang@cug.edu.cn

中图分类号: P592
计量
- 文章访问数: 3131
- HTML全文浏览量: 200
- PDF下载量: 446
- 被引次数: 0
出版历程
- 收稿日期: 2013-05-06
- 刊出日期: 2014-01-01

Molybdenum Isotope Geochemistry of Arsenic Mobilization in Groundwater System

1.
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
2.
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China

摘要

摘要: 砷在天然环境中的迁移富集与氧化还原状态密切相关.盆地环境地下水中砷的活化迁移机制主要为沉积物中铁/锰氢氧化物由氧化还原条件变化导致发生还原性溶解进而释放吸附在其表面的砷.钼及钼同位素为氧化还原环境的重要指示参数, 且铁/锰氢氧化物对钼同位素分馏有着重要的控制作用.将地下水的钼同位素应用于砷的活化迁移规律研究.大同盆地地下水中钼同位素比值(δ⁹⁸Mo)范围为-0.12‰~+2.17‰, 相比于淡水中钼同位素组成偏重.桑干河河水的δ⁹⁸Mo为+0.72‰, 与文献报道的河水平均钼同位素比值+0.7‰相当.大同盆地地下水中δ⁹⁸Mo与硫化物之间存在正相关关系, 表明Mo-Fe-S复合物可能形成于特定条件下, 并优先利用水溶液中轻的钼使地下水中δ⁹⁸Mo比值升高.砷浓度与钼浓度之间的微弱负相关以及砷浓度与钼同位素之间的正相关说明, Mo-Fe-S的形成过程可能与同环境中As-Fe-S的复合物的形成存在竞争关系, 进而使得地下水中砷富集.地下水中相对偏高的δ⁹⁸Mo可能来源于铁的氢氧化物对溶液中轻的钼的吸附速率高于先前吸附在铁的氢氧化物的钼的释放, 且铁的氢氧化物对水溶液中钼的再吸附这一循环过程会导致地下水中钼浓度降低及钼同位素比值的升高.钼同位素指示的循环性的铁的氢氧化物的还原溶解及再氧化过程对砷的富集也有重要影响.
- 砷 /
- 钼同位素 /
- 铁锰氢氧化物 /
- 氧化还原反应 /
- 地球化学 /
- 大同盆地
Abstract: Arsenic (AS) mobilization is closely linked to redox state in nature.In basin environment, the primary mechanism governing arsenic mobility is the reductive dissolution of Fe/Mn-(hydr)oxides which results in the subsequent As released into groundwater. Molybdenum (Mo) and Mo isotope can be informative of the redox conditions. Moreover, Mo isotope fractionation is mainly controlled by the adsorption and desorption onto/from Fe/Mn-(hydr)oxides. This study applies Mo isotope ratio(δ⁹⁸Mo) of dissolved Mo in groundwater to arsenic mobilization in groundwater system for the very first time. The Mo isotope ratios (δ⁹⁸Mo) in groundwater in Datong basin range from -0.12‰ to 2.17‰, which are relatively heavier than those reported in fresh waters. δ⁹⁸Mo of Sanggan River shows a value of 0.72‰, comparable to the average δ⁹⁸Mo of riverine Mo isotopic composition of 0.7‰.δ⁹⁸Mo ratios of groundwater in Datong basin are positively correlated to dissolved sulfide, indicating that the formation of Mo-Fe-S complex preferentially co-precipitated the light Mo in groundwater resulting in the gradually increased δ⁹⁸Mo values under certain condition. The formation of Mo-Fe-S complex might be competitive to the similar formation of As-Fe-S complex, as is further confirmed by the weak correlation between As and Mo concentrations and the positive relationship between As and δ⁹⁸Mo ratios. This process leads to an elevation of As content in groundwater.The relatively heavier δ⁹⁸Mo ratio of groundwater might be a consequence of the faster rate of adsorption of light Mo from groundwater than the rate of desorption of Mo from Fe-(hydr)oxides and the re-adsorption of dissolved Mo in groundwater.The progressive processes decrease Mo content and elevate δ⁹⁸Mo ratio in groundwater, which is consistent with the observation in groundwater in Datong basin.The indicative δ⁹⁸Mo ratio of groundwater indicates that the reductive dissolution of Fe-(hydr)oxides also has important influence on arsenic mobilization in groundwater.
- arsenic /
- Mo isotope /
- Fe/Mn-(hydr) oxides /
- redox reactions /
- geochemistry /
- Datong basin

HTML全文

图 1 研究区地质图及采样点分布(图中实心点为钼同位素分析样品分布)

Fig. 1. Geological map of study area and sample locations

下载: 全尺寸图片幻灯片

图 2 地下水中钼同位素δ⁹⁸Mo与溶解硫化物的关系

Fig. 2. Relationship between δ⁹⁸Mo and dissolved S^2- in groundwater

下载: 全尺寸图片幻灯片

图 3 地下水中钼同位素δ⁹⁸Mo与Fe²⁺, Fe_total, Mn的关系

Fig. 3. Relationships between δ⁹⁸Mo and Fe²⁺, Fe_total, and Mn in groundwater

下载: 全尺寸图片幻灯片

图 4 地下水中钼的浓度及钼同位素比值δ⁹⁸Mo的关系

Fig. 4. Mo concentrations versus δ⁹⁸Mo in groundwater

下载: 全尺寸图片幻灯片

图 5 地下水中钼同位素组成δ⁹⁸Mo与pH值的关系

Fig. 5. Relationship between δ⁹⁸Mo and pH in groundwater

下载: 全尺寸图片幻灯片

图 6 地下水中砷与亚铁、总铁、钼及钼同位素的关系

Fig. 6. Relationships between As and Fe²⁺, Fe_total, Mo and δ⁹⁸Mo in groundwater

下载: 全尺寸图片幻灯片

表 1 大同盆地地下水中钼同位素组成及砷、铁、锰和其他物理化学参数

Table 1. Mo isotopic composition and Mo, As, Fe, Mn and other physicochemical parameters in groundwater in Datong basin

样品编号	深度(m)	pH	Ec(μs/cm)	S^2-(μg/L)	Fe²⁺(mg/L)	Fe_total(mg/L)	SO₄(mg/L)	As(μg/L)	Mn(μg/L)	Mo(μg/L)	δ⁹⁸Mo(‰)
1	30	7.80	2 320	0	0.13	0.17	576.0	144.00	162.00	2.60	0.80
2	90	8.12	484	1	0.12	0.11	50.0	16.00	5.43	1.94	1.25
3	25	8.18	842	4	0.03	0.06	28.3	368.00	27.00	7.32	0.88
4	30	7.89	1 870	19	0.10	0.72	237.0	875.00	179.00	2.98	2.14
5	20	7.82	1 169	1	0.13	0.15	46.4	679.00	62.10	9.75	1.02
6	18	8.09	1 240	-2	0.08	0.07	170.0	8.19	6.20	39.30	0.73
7	100	8.58	2 000	22	0.28	1.01	82.1	221.00	23.80	14.30	1.56
8		7.23	878	42	0.01	0.03	293.0	3.66	2.30	24.50	0.72
9	6	7.93	1 344	7	0.02	0.00	250.0	14.30	1.30	13.00	1.20
10	70	7.91	1 865	24	0.07	0.40	111.0	299.00	26.70	2.15	2.17
11	36	7.98	436	193	0.08	0.05	12.9	381.00	130.00	1.32	1.10
12	10	7.61	1 295	4	0.10	0.14	145.0	15.10	30.50	3.44	0.60
13	20	8.06	1 089	12	0.04	0.04	97.2	32.30	21.90	5.58	1.09
14	70	7.78	580	28	0.03	0.62	49.3	11.10	13.70	4.49	0.89
15	35	7.86	1 601	-1	0.03	0.04	237.0	3.55	559.00	27.30	-0.12
16	25	8.13	3 300	12	0.03	0.03	571.0	12.60	3.69	23.50	1.14

下载: 导出CSV

参考文献(51)

[1]	Anbar, A.D., 2004. Molybdenum Stable Isotopes: Observations, Interpretations and Directions. Reviews in Mineralogy and Geochemistry, 55(1): 429-454. doi: 10.2138/gsrmg.55.1.429
[2]	Archer, C., Vance, D., 2008. The Isotopic Signature of the Global Riverine Molybdenum Flux and Anoxia in the Ancient Oceans. Nature Geoscience, 1(9): 597-600. doi: 10.1038/ngeo282
[3]	Argos, M., Kalra, T., Rathouz, P.J., et al., 2010. Arsenic Exposure from Drinking Water, and All-Cause and Chronic-Disease Mortalities in Bangladesh (HEALS): A Prospective Cohort Study. Lancet, 376(9737): 252-258. doi: 10.1016/s0140-6736(10)60481-3
[4]	Arnold, G.L., Anbar, A.D., Barling, J., et al., 2004. Molybdenum Isotope Evidence for Widespread Anoxia in Mid-Proterozoic Oceans. Science, 304(5667): 87-90. doi: 10.1126/science.1091785
[5]	Barling, J., Anbar, A.D., 2004. Molybdenum Isotope Fractionation during Adsorption by Manganese Oxides. Earth and Planetary Science Letters, 217(3-4): 315-329. doi10.1016/S0012-821x(03)00608-3 doi: 10.1016/S0012-821X(03)00608-3
[6]	Barling, J., Arnold, G.L., Anbar, A.D., 2001. Natural Mass-Dependent Variations in the Isotopic Composition of Molybdenum. Earth and Planetary Science Letters, 193(3): 447-457. doi: 10.1016/S0012-821X(01)00514-3
[7]	Burton, E.D., Johnston, S.G., Bush, R.T., 2011. Microbial Sulfidogenesis in Ferrihydrite-Rich Environments: Effects on Iron Mineralogy and Arsenic Mobility. Geochimica et Cosmochimica Acta, 75(11): 3072-3087. doi: 10.1016/j.gca.2011.03.001
[8]	Burton, E.D., Johnston, S.G., Planer-Friedrich, B., 2013. Coupling of Arsenic Mobility to Sulfur Transformations during Microbial Sulfate Reduction in the Presence and Absence of Humic Acid. Chemical Geology, 343: 12-24. doi10.1016/j. chemgeo. 2013.02.005 doi: 10.1016/j.chemgeo.2013.02.005
[9]	Collier, R.W., 1985. Molybdenum in the Northeast Pacific Ocean. Limnology and Oceanography, 30(6): 1351-1354. doi: 10.4319/lo.1985.30.6.1351/full
[10]	Coplen,T.B.,2011.Guidelines and Recommended Terms for Expression of Stable-Isotope-Ratio and Gas-Ratio Measurement Results.Rapid Communications in Mass Spectrometry,25(17):2538-2560.doi: 10.1002/rcm.5129.doi:10.1016/j.gca.2009.11.028
[11]	Couture, R.M., Gobeil, C., Tessier, A., 2010. Arsenic, Iron and Sulfur Co-diagenesis in Lake Sediments. Geochimica et Cosmochimica Acta, 74(4): 1238-1255. doi: 10.1016/j.gca.2009.11.028
[12]	Dahl, T.W., Anbar, A.D., Gordon, G.W., et al., 2010. The Behavior of Molybdenum and Its Isotopes across the Chemocline and in the Sediments of Sulfidic Lake Cadagno, Switzerland. Geochimica et Cosmochimica Acta, 74(1): 144-163. doi: 10.1016/j.gca.2009.09.018
[13]	Dahl, T.W., Canfield, D.E., Rosing, M.T., et al., 2011. Molybdenum Evidence for Expansive Sulfidic Water Masses in Similar to 750 Ma Oceans. Earth and Planetary Science Letters, 311(3-7): 264-274. doi10.1016/j. epsl. 2011.09.016 http://www.sciencedirect.com/science/article/pii/S0012821X11005309
[14]	Dahl, T.W., Chappaz, A., Fitts, J.P., et al., 2013. Molysbdenum Reduction in a Sulfidic Lake: Evidence from X-Ray Absorption Fine-Structure Spectroscopy and Implications for the Mo Paleoproxy. Geochimica et Cosmochimica Acta, 103: 213-231. doi: 10.1016/j.gca.2012.10.058
[15]	Erickson, B.E., Helz, G.R., 2000. Molybdenum(VI) Speciation in Sulfidic Waters: Stability and Lability of Thiomolybdates. Geochimica et Cosmochimica Acta, 64(7): 1149-1158. doi: 10.1016/S0016-7037(99)00423-8
[16]	Fendorf, S., Michael, H.A., van Geen, A., 2010. Spatial and Temporal Variations of Groundwater Arsenic in South and Southeast Asia. Science, 328(5982): 1123-1127. doi: 10.1126/science.1172974
[17]	Glass, J.B., Chappaz, A., Eustis, B., et al., 2013. Molybdenum Geochemistry in a Seasonally Dysoxic Mo-Limited Lacustrine Ecosystem. Geochimica et Cosmochimica Acta, 114: 204-219. doi: 10.1016/j.gca.2013.03.023
[18]	Goldberg, T., Archer, C., Vance, D., et al., 2009. Mo Isotope Fractionation during Adsorption to Fe (Oxyhydr)oxides. Geochimica et Cosmochimica Acta, 73(21): 6502-6516. doi: 10.1016/j.gca.2009.08.004
[19]	Goldberg, T., Archer, C., Vance, D., et al., 2012. Controls on Mo Isotope Fractionations in a Mn-Rich Anoxic Marine Sediment, Gullmar Fjord, Sweden. Chemical Geology, 296-297: 73-82. doi: 10.1016/j.chemgeo.2011.12.020
[20]	Guo, H., Liu, C., Lu, H., et al., 2013. Pathways of Coupled Arsenic and Iron Cycling in High Arsenic Groundwater of the Hetao Basin, Inner Mongolia, China: An Iron Isotope Approach. Geochimica et Cosmochimica Acta, 112: 130-145. doi: 10.1016/j.gca.2013.02.031
[21]	Gustafsson, J.P., 2003. Modelling Molybdate and Tungstate Adsorption to Ferrihydrite. Chemical Geology, 200(1-2): 105-115. doi: 10.1016/S0009-2541(03)00161-X
[22]	Handley, K.M., McBeth, J.M., Charnock, J.M., et al., 2013. Effect of Iron Redox Transformations on Arsenic Solid-Phase Associations in an Arsenic-Rich, Ferruginous Hydrothermal Sediment. Geochimica et Cosmochimica Acta, 102: 124-142. doi: 10.1016/j.gca.2012.10.024
[23]	Helz, G.R., Bura-Nakic, E., Mikac, N., et al., 2011. New Model for Molybdenum Behavior in Euxinic Waters. Chemical Geology, 284(3-4): 323-332. doi: 10.1016/j.chemgeo.2011.03.012
[24]	Helz, G.R., Miller, C.V., Charnock, J.M., et al., 1996. Mechanism of Molybdenum Removal from the Sea and Its Concentration in Black Shales: EXAFS Evidence. Geochimica et Cosmochimica Acta, 60(19): 3631-3642. doi: 10.1016/0016-7037(96)00195-0
[25]	Helz, G.R., Vorlicek, T.P., Kahn, M.D., 2004. Molybdenum Scavenging by Iron Monosulfide. Environmental Science & Technology, 38(16): 4263-4268. doi: 10.1021/es.034969+
[26]	McManus, J., Nagler, T.F., Wheat, C.G., et al., 2002. Oceanic Molybdenum Isotope Fractionation: Diagenesis and Hydrothermal Ridge-Flank Alteration. Geochemistry, Geophysics, Geosystems, 3(12): 1-9. doi: 10.1029/2002GC000356
[27]	Nagler, T.F., Neubert, N., Bottcher, M.E., et al., 2011. Molybdenum Isotope Fractionation in Pelagic Euxinia: Evidence from the Modern Black and Baltic Seas. Chemical Geology, 289(1-2): 1-11. doi10.1016/j. chemgeo. 2011.07.001 doi: 10.1016/j.chemgeo.2011.07.001
[28]	Neubert, N., Nagler, T.F., Bottcher, M.E., 2008. Sulfidity Controls Molybdenum Isotope Fractionation into Euxinic Sediments: Evidence from the Modern Black Sea. Geology, 36(10): 775-778. doi: 10.1130/G24959A.1
[29]	Poulson, R.L., Mcmanus, J., Siebert, C., et al., 2006. Molybdenum Isotopes in Modern Marine Sediments: Unique Signatures of Authigenic Processes. Geochimica et Cosmochimica Acta, 70(18): A501. doi: 10.1016/j.gca.2006.06.1464
[30]	Poulton, S.W., Raiswell, R., 2002. The Low-Temperature Geochemical Cycle of Iron: From Continental Fluxes to Marine Sediment Deposition. American Journal of Science, 302(9): 774-805. doi: 10.2475/ajs.302.9.774
[31]	Rodríguez-Lado, L., Sun, G., Berg, M., et al., 2013. Groundwater Arsenic Contamination throughout China. Science, 341(6148): 866-868. doi: 10.1126/science.1237484
[32]	Siebert, C., McManus, J., Bice, A., et al., 2006. Molybdenum Isotope Signatures in Continental Margin Marine Sediments. Earth and Planetary Science Letters, 241(3-4): 723-733. doi: 10.1016/j.epsl.2005.11.010
[33]	Siebert, C., Nagler, T.F., von Blanckenburg, F., et al., 2003. Molybdenum Isotope Records as a Potential New Proxy for Paleoceanography. Earth and Planetary Science Letters, 211(1-2): 159-171. doi: 10.1016/S0012-821X(03)00189-4
[34]	Smedley, P.L., Kinniburgh, D.G., 2002. A Review of the Source, Behaviour and Distribution of Arsenic in Natural Waters. Applied Geochemistry, 17(5): 517-568. doi: 10.1016/S0883-2927(02)00018-5
[35]	Sugár, É., Tatár, E., Záray, G., et al., 2013. Field Separation-Based Speciation Analysis of Inorganic Arsenic in Public Well Water in Hungary. Microchemical Journal, 107: 131-135. doi: 10.1016/j.microc.2012.05.025
[36]	Thamdrup, B., 2000. Bacterial Manganese and Iron Reduction in Aquatic Sediments. Advances in Microbial Ecology, 16: 41-84. doi: 10.1007/978-1-4615-4187-5_2
[37]	Tossell, J.A., 2005. Calculating the Partitioning of the Isotopes of Mo between Oxidic and Sulfidic Species in Aqueous Solution. Geochimica et Cosmochimica Acta, 69(12): 2981-2993. doi: 10.1016/j.gca.2005.01.016
[38]	Vorlicek, T.P., Kahn, M.D., Kasuya, Y., et al., 2004. Capture of Molybdenum in Pyrite-Forming Sediments: Role of Ligand-Induced Reduction by Polysulfides. Geochimica et Cosmochimica Acta, 68(3): 547-556. doi: 10.1016/S0016-7037(00)00444-7
[39]	Wang, S.L., Mulligan, C.N., 2006. Natural Attenuation Processes for Remediation of Arsenic Contaminated Soils and Groundwater. Journal of Hazardous Materials, 138(3): 459-470. doi: 10.1016/j.jhazmat.2006.09.048
[40]	WHO, 2004. Guidelines for Drinking Water Quality. WHO Press, Switzerland, 145-196.
[41]	Wille, M., Kramers, J.D., Nagler, T.F., et al., 2007. Evidence for a Gradual Rise of Oxygen between 2.6 and 2.5 Ga from Mo Isotopes and Re-PGE Signatures in Shales. Geochimica et Cosmochimica Acta, 71(10): 2417-2435. doi: 10.1016/j.gca.2007.02.019.
[42]	Xie, X.J., Ellis, A., Wang, Y.X., et al., 2009. Geochemistry of Redox-Sensitive Elements and Sulfur Isotopes in the High Arsenic Groundwater System of Datong Basin, China. Science of the Total Environment, 407(12): 3823-3835. doi: 10.1016/j.scitotenv.2009.01.041
[43]	Xie, X.J., Wang, Y.X., Li, J.X., et al., 2012. Charateristics and Implications of Rare Earth Elements in High Arsenic Groundwater from the Datong Basin. Earth Science-Journal of China Univeristy of Geosciences, 37(2): 381-390 (in Chinses with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQKX201202030.htm
[44]	Xu, L.G., Lehmann, B., 2011. Mo and Mo Stable Isotope Geochemistry: Isotope System, Analytical Technique and Applications to Geology. Mineral Deposits, 30(1): 103-124 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTotal-KCDZ201101010.htm
[45]	Zheng, Y., Anderson, R.F., Geen, V.A., et al., 2000. Authigenic Molybdenum Formation in Marine Sediments: A Link to Pore Water Sulfide in the Santa Barbara Basin. Geochimica et Cosmochimica Acta, 64(24): 4165-4178. doi: 10.1016/S0016-7037(00)00495-6
[46]	Zhou, L., Su, J., Huang, J.H., et al., 2011. A New Paleoenvironmental Index for Anoxic Events-Mo Isotopes in Black Shales from Upper Yangtze Marine Sediments. Sci. China Earth Sci. , 41(3): 309-319 (in Chinese). doi: 10.1007/s11430-011-4188-z
[47]	Zhou, L., Zhou, H.B., Li, M., et al., 2007. Molybdenum Isotope Signatures from Yangtze Craton Continental Margin and Its Indication to Organic Burial Rate. Earth Science-Journal of China Univeristy of Geosciences, 32(6): 759-766 (in Chinses with English abstract). doi: 10.1007/s11707-007-0051-0
[48]	谢先军, 王焰新, 李俊霞, 等, 2012. 大同盆地高砷地下水稀土元素特征及其指示意义. 地球科学—中国地质大学学报, 37(2): 381-390. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX201202030.htm
[49]	徐林刚, Lehmann, B., 2011. 钼及钼同位素地球化学—同位素体系、测试技术及在地质中的应用. 矿床地质, 30(1): 103-124. doi: 10.3969/j.issn.0258-7106.2011.01.009
[50]	周炼, 苏洁, 黄俊华, 等, 2011. 判识缺氧事件的地球化学新标志—钼同位素. 中国科学: 地球科学, 41(3): 309-319. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK201103004.htm
[51]	周炼, 周红兵, 李茉, 等, 2007. 扬子克拉通古大陆边缘Mo同位素特征及对有机埋藏量的指示意义. 地球科学—中国地质大学学报, 32(6): 759-766. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200706006.htm