Hydrogeochemical anomaly of mercury in the high-temperature geothermal waters in the Rehai hydrothermal area in Tengchong, Yunnan and its indications

doi:10.13745/j.esf.sf.2019.9.7

Abstract

Abstract:

Mercury (Hg) is a typical undesirable constituent in the environment. One of potential sources of environmental mercury is deep geothermal systems. However, systematic studies on geothermal mercury are sparse. Here, we conducted a hydrogeochemical study on Hg in hot springs in the Rehai hydrothermal area in the Tengchong volcanic region. The results showed that Hg is rich in the neutral hot springs in the Rehai area but was not detected in most acidic Rehai hot springs. Moreover, the geothermal mercury in Rehai, like chlorine, a typical magma-derived component, primarily comes from magmatic fluid. In the neutral hot springs, Hg(II) is the predominant form of mercury. Complexation of Hg²⁺ with different sulfide species directly determines Hg(II) speciation, but hot spring pH values can also have an effect to some degrees by controlling sulfide speciation. Because Hg(II) is not prone to volatilization, the neutral hot springs generally have high mercury concentrations. However, volatile Hg(0) is the major form of mercury in acidic Rehai hot springs due to their much higher redox potentials, resulting in very low total mercury concentrations in acidic springs. Mercury in neutral hot springs can be an effective indicator for fault distribution in Rehai, because mercury concentration in ascending neutral spring waters varies distinctively depending on the water cooling process along fault. Geothermal mercury is of great significance for studying the structures of hydrothermal systems.

Key words: hot spring, mercury, speciation, geochemical anomaly, fault

CLC Number:

GUO Qinghai, WU Qifan. Hydrogeochemical anomaly of mercury in the high-temperature geothermal waters in the Rehai hydrothermal area in Tengchong, Yunnan and its indications[J]. Earth Science Frontiers, 2020, 27(1): 103-111.

Figures/Tables 12

Fig.1 Simplified geological map of the Rehai hydrothermal area (Left) and sampling locations (Right)

Table 1 Summary of water sampling information, in-situ parameters and mercury concentrations

样品编号	采样位置	所属子区	pH	t/℃	EC/(μS·cm^-1)	DO质量浓度/(mg·L^-1)	Hg质量浓度/(μg·L^-1)
LGG-HT	老滚锅	硫磺塘	4.87	72.3	902.3	n.d.	n.d.
LGG-LT	老滚锅	硫磺塘	4.60	56.2	916.7	1.46	n.d.
DRTY-01	地热体验区	硫磺塘	1.60	46.7	4 639	5.84	n.d.
DRTY-02	地热体验区	硫磺塘	1.80	68.3	2 184	0.34	n.d.
DRTY-03	地热体验区	硫磺塘	1.93	71.8	1 494	0.21	n.d.
DRTY-04	地热体验区	硫磺塘	2.14	62.6	1 317	0.24	n.d.
DRTY-10	地热体验区	硫磺塘	1.59	49.9	5 857	1.40	n.d.
DRTY-11	地热体验区	硫磺塘	2.19	82.9	604.5	0.49	n.d.
WGQ	文光泉	硫磺塘	5.36	38.4	382.8	0.09	n.d.
ZZQ	珍珠泉	硫磺塘	3.46	93.0	558.9	0.58	0.024
TQL	听泉楼	硫磺塘	8.12	82.9	3 552	0.20	0.796
YJQ-L	眼镜泉-左	硫磺塘	8.31	91.8	3 753	0.53	1.046
GMQ	鼓鸣泉	硫磺塘	8.30	92.5	3 601	0.31	0.939
HTJ-L	怀胎井-左	硫磺塘	7.56	92.2	3 473	0.52	0.939
HTJ-R	怀胎井-右	硫磺塘	6.77	82.4	2 752	0.38	0.765
DGG	大滚锅	硫磺塘	6.87	85.7	4 419	0.30	1.472
XKT-L	霞客亭-左	澡塘河	7.32	79.9	2 236	0.94	0.486
XKT-R	霞客亭-右	澡塘河	7.64	94.8	2 362	0.37	0.455
ZTH	澡塘河热泉	澡塘河	7.51	80.7	2 326	0.56	0.405
HMZ	蛤蟆嘴	澡塘河	7.70	74.5	2 814	0.27	0.422
HMZP-R	蛤蟆嘴坡-右	澡塘河	7.13	93.1	2 436	0.23	0.524

Table 2 Hydrochemical and water isotopic compositions of the hot springs

样品编号	组分质量浓度/(mg·L^-1)															As质量浓度/ (μg·L^-1)	δD/‰	δ¹⁸O/‰
样品编号	HCO₃	CO₃	SO₄	Cl	F	Br	Na	K	Ca	Mg	Fe	Si	Li	B	硫化物	As质量浓度/ (μg·L^-1)	δD/‰	δ¹⁸O/‰
LGG-HT	0.0	0.00	436.2	42.8	2.69	0.29	208.4	38.2	6.64	1.05	0.47	139.1	2.86	1.33	0.17	35.7	n.a.	n.a.
LGG-LT	0.0	0.00	490.2	45.5	2.50	0.32	210.2	38.8	6.96	1.09	0.45	141.3	2.90	1.34	0.00	28.8	-53	-7.6
DRTY-01	0.0	0.00	3 548	30.1	2.33	n.d.	46.2	136.9	26.6	3.93	46.0	120.2	3.36	0.30	2.20	46.5	-58	-7.3
DRTY-02	0.0	0.00	1 894	29.5	2.33	n.d.	7.72	19.1	16.0	1.78	27.7	69.3	0.49	0.20	0.17	100	-55	-8.1
DRTY-03	0.0	0.00	667.0	12.6	1.04	n.d.	11.4	19.7	1.95	1.03	12.5	76.9	1.72	0.08	0.20	127	-60	-7.7
DRTY-04	0.0	0.00	694.6	10.1	0.91	n.d.	26.0	44.7	1.82	1.11	20.4	178.5	4.12	0.14	0.12	261	-67	-9.3
DRTY-10	0.0	0.00	15 590	50.9	15.2	n.d.	29.8	209.8	35.6	8.74	60.2	132.6	3.21	0.39	0.05	n.d.	-59	-9.6
DRTY-11	0.0	0.00	320.4	4.95	n.d.	n.d.	0.42	1.83	0.17	0.05	0.81	11.7	0.06	0.01	0.04	4.4	-56	-7.2
WGQ	60.8	0.01	175.1	5.53	1.21	n.d.	82.5	27.8	8.82	1.22	2.01	107.2	1.29	0.06	0.75	51.9	n.a.	n.a.
ZZQ	38.4	0.00	163.3	52.7	1.34	0.33	84.3	35.1	4.47	0.98	1.31	83.2	0.75	1.29	0.04	88.6	-64	-7.2
TQL	886	59.8	45.4	596.3	16.4	1.87	677.5	102.2	1.97	0.28	n.d.	108.9	8.04	9.88	2.60	751	n.a.	n.a.
YJQ-L	851	98.3	55.0	635.6	17.1	1.96	701.5	119.5	1.80	0.27	n.d.	121.0	8.35	10.07	5.90	897	n.a.	n.a.
GMQ	854	81.4	46.7	588.1	16.3	1.72	671.0	115.3	1.93	0.29	n.d.	134.8	8.04	9.73	5.20	837	-67	-7.5
HTJ-L	913	34.0	49.9	583.1	16.2	1.85	639.0	106.7	1.62	0.29	n.d.	114.4	7.58	9.19	4.20	802	-66	-7.7
HTJ-R	739	6.38	68.8	433.8	12.6	1.61	507.5	84.9	2.13	0.32	n.d.	116.2	6.11	7.41	2.10	593	n.a.	n.a.
DGG	1 256	5.73	40.8	738.1	19.9	2.35	858.0	150.0	1.77	0.26	n.d.	152.0	9.90	12.01	0.24	1 059	-65	-7.3
XKT-L	641	6.62	69.4	323.1	9.91	1.27	408.0	71.4	6.18	0.60	n.d.	72.3	4.66	5.56	0.17	305	n.a.	n.a.
XKT-R	720	14.2	46.3	309.3	9.67	n.d.	437.6	76.5	4.01	0.36	0.01	77.2	5.18	5.80	0.71	257	n.a.	n.a.
ZTH	691	11.1	59.6	338.7	10.5	n.d.	436.1	76.2	3.87	0.51	n.d.	79.4	4.99	5.88	0.60	255	-65	-8.4
HMZ	585	9.88	39.7	270.7	9.29	1.22	355.6	64.2	13.7	1.84	n.d.	65.1	4.15	5.03	0.31	151	n.a.	n.a.
HMZP-R	722	8.65	45.3	326.9	10.2	n.d.	429.6	73.7	6.72	0.63	0.15	75.5	4.89	5.88	0.43	264	n.a.	n.a.

Table 2 Hydrochemical and water isotopic compositions of the hot springs

样品编号	组分质量浓度/(mg·L^-1)															As质量浓度/ (μg·L^-1)	δD/‰	δ¹⁸O/‰
样品编号	HCO₃	CO₃	SO₄	Cl	F	Br	Na	K	Ca	Mg	Fe	Si	Li	B	硫化物	As质量浓度/ (μg·L^-1)	δD/‰	δ¹⁸O/‰
LGG-HT	0.0	0.00	436.2	42.8	2.69	0.29	208.4	38.2	6.64	1.05	0.47	139.1	2.86	1.33	0.17	35.7	n.a.	n.a.
LGG-LT	0.0	0.00	490.2	45.5	2.50	0.32	210.2	38.8	6.96	1.09	0.45	141.3	2.90	1.34	0.00	28.8	-53	-7.6
DRTY-01	0.0	0.00	3 548	30.1	2.33	n.d.	46.2	136.9	26.6	3.93	46.0	120.2	3.36	0.30	2.20	46.5	-58	-7.3
DRTY-02	0.0	0.00	1 894	29.5	2.33	n.d.	7.72	19.1	16.0	1.78	27.7	69.3	0.49	0.20	0.17	100	-55	-8.1
DRTY-03	0.0	0.00	667.0	12.6	1.04	n.d.	11.4	19.7	1.95	1.03	12.5	76.9	1.72	0.08	0.20	127	-60	-7.7
DRTY-04	0.0	0.00	694.6	10.1	0.91	n.d.	26.0	44.7	1.82	1.11	20.4	178.5	4.12	0.14	0.12	261	-67	-9.3
DRTY-10	0.0	0.00	15 590	50.9	15.2	n.d.	29.8	209.8	35.6	8.74	60.2	132.6	3.21	0.39	0.05	n.d.	-59	-9.6
DRTY-11	0.0	0.00	320.4	4.95	n.d.	n.d.	0.42	1.83	0.17	0.05	0.81	11.7	0.06	0.01	0.04	4.4	-56	-7.2
WGQ	60.8	0.01	175.1	5.53	1.21	n.d.	82.5	27.8	8.82	1.22	2.01	107.2	1.29	0.06	0.75	51.9	n.a.	n.a.
ZZQ	38.4	0.00	163.3	52.7	1.34	0.33	84.3	35.1	4.47	0.98	1.31	83.2	0.75	1.29	0.04	88.6	-64	-7.2
TQL	886	59.8	45.4	596.3	16.4	1.87	677.5	102.2	1.97	0.28	n.d.	108.9	8.04	9.88	2.60	751	n.a.	n.a.
YJQ-L	851	98.3	55.0	635.6	17.1	1.96	701.5	119.5	1.80	0.27	n.d.	121.0	8.35	10.07	5.90	897	n.a.	n.a.
GMQ	854	81.4	46.7	588.1	16.3	1.72	671.0	115.3	1.93	0.29	n.d.	134.8	8.04	9.73	5.20	837	-67	-7.5
HTJ-L	913	34.0	49.9	583.1	16.2	1.85	639.0	106.7	1.62	0.29	n.d.	114.4	7.58	9.19	4.20	802	-66	-7.7
HTJ-R	739	6.38	68.8	433.8	12.6	1.61	507.5	84.9	2.13	0.32	n.d.	116.2	6.11	7.41	2.10	593	n.a.	n.a.
DGG	1 256	5.73	40.8	738.1	19.9	2.35	858.0	150.0	1.77	0.26	n.d.	152.0	9.90	12.01	0.24	1 059	-65	-7.3
XKT-L	641	6.62	69.4	323.1	9.91	1.27	408.0	71.4	6.18	0.60	n.d.	72.3	4.66	5.56	0.17	305	n.a.	n.a.
XKT-R	720	14.2	46.3	309.3	9.67	n.d.	437.6	76.5	4.01	0.36	0.01	77.2	5.18	5.80	0.71	257	n.a.	n.a.
ZTH	691	11.1	59.6	338.7	10.5	n.d.	436.1	76.2	3.87	0.51	n.d.	79.4	4.99	5.88	0.60	255	-65	-8.4
HMZ	585	9.88	39.7	270.7	9.29	1.22	355.6	64.2	13.7	1.84	n.d.	65.1	4.15	5.03	0.31	151	n.a.	n.a.
HMZP-R	722	8.65	45.3	326.9	10.2	n.d.	429.6	73.7	6.72	0.63	0.15	75.5	4.89	5.88	0.43	264	n.a.	n.a.

Fig.2 Giggenbach's Na-K-Mg triangular diagram of all hot spring samples collected from the Rehai hydrothermal area. Symbols: ○Neutral hot springs; □Steam-heated acidic hot springs; △Steam-heated acidic hot springs mixing with some neutral geothermal waters.

Fig.3 Plot of δD vs. δ18O for the hot spring samples and indications for geothermal geochemical origin

Fig.4 A conceptual model of the geochemical origin of various geothermal waters in Rehai

Table 3 Simulated concentrations of various Hg species in the Rehai hot springs

样品编号	汞质量浓度/(mol·L^-1)
	Hg(0)	Hg(I)	Hg(II)
	Hg	H $g 2 2 +$	HgH $S 2 -$	Hg $S 2 2 -$	Hg(HS)₂	Hg(OH)₂
ZZQ	1.08E-10	1.13E-32	1.49E-14	1.18E-19	1.14E-11	8.96E-32
TQL	3.98E-12	0.00E+00	2.55E-09	1.38E-09	3.75E-11	4.21E-30
YJQ-L	2.90E-10	5.01E-40	2.62E-09	2.30E-09	2.44E-11	4.21E-30
GMQ	9.13E-11	0.00E+00	2.49E-09	2.09E-09	2.40E-11	4.83E-30
HTJ-L	9.41E-11	2.85E-40	3.82E-09	5.73E-10	2.03E-10	2.45E-31
HTJ-R	1.24E-10	3.14E-39	2.72E-09	5.98E-11	9.21E-10	6.98E-32
DGG	5.46E-10	2.15E-36	5.30E-09	1.76E-10	1.34E-09	1.29E-29
XKT-L	3.38E-13	2.16E-40	2.07E-09	1.52E-10	2.02E-10	2.51E-29
XKT-R	6.73E-10	1.89E-38	1.33E-09	2.09E-10	6.16E-11	3.83E-30
ZTH	6.05E-12	0.00E+00	1.71E-09	1.97E-10	1.08E-10	3.00E-30
HMZ	3.61E-14	0.00E+00	1.74E-09	2.93E-10	7.19E-11	1.86E-29
HMZP-R	5.19E-10	8.93E-38	1.75E-09	8.51E-11	2.62E-10	2.28E-30

Table 3 Simulated concentrations of various Hg species in the Rehai hot springs

样品编号	汞质量浓度/(mol·L^-1)
	Hg(0)	Hg(I)	Hg(II)
	Hg	H $g 2 2 +$	HgH $S 2 -$	Hg $S 2 2 -$	Hg(HS)₂	Hg(OH)₂
ZZQ	1.08E-10	1.13E-32	1.49E-14	1.18E-19	1.14E-11	8.96E-32
TQL	3.98E-12	0.00E+00	2.55E-09	1.38E-09	3.75E-11	4.21E-30
YJQ-L	2.90E-10	5.01E-40	2.62E-09	2.30E-09	2.44E-11	4.21E-30
GMQ	9.13E-11	0.00E+00	2.49E-09	2.09E-09	2.40E-11	4.83E-30
HTJ-L	9.41E-11	2.85E-40	3.82E-09	5.73E-10	2.03E-10	2.45E-31
HTJ-R	1.24E-10	3.14E-39	2.72E-09	5.98E-11	9.21E-10	6.98E-32
DGG	5.46E-10	2.15E-36	5.30E-09	1.76E-10	1.34E-09	1.29E-29
XKT-L	3.38E-13	2.16E-40	2.07E-09	1.52E-10	2.02E-10	2.51E-29
XKT-R	6.73E-10	1.89E-38	1.33E-09	2.09E-10	6.16E-11	3.83E-30
ZTH	6.05E-12	0.00E+00	1.71E-09	1.97E-10	1.08E-10	3.00E-30
HMZ	3.61E-14	0.00E+00	1.74E-09	2.93E-10	7.19E-11	1.86E-29
HMZP-R	5.19E-10	8.93E-38	1.75E-09	8.51E-11	2.62E-10	2.28E-30

Fig.5 Relations between concentrations of four Hg(II) species ( HgHS 2 -, HgS 2 2 -, Hg(HS)2, Hg(OH)2) and sulfide concentration (a) or pH (b) in neutral hot springs

Fig.6 Relations between Hg and Cl (a) or As (b) concentrations in the hot springs

Table 4 Saturation indices of hot spring samples with respects to cinnabar and meta-cinnabar

样品编号	饱和指数		样品编号	饱和指数
样品编号	辰砂	黑辰砂	样品编号	辰砂	黑辰砂
ZZQ	-5.81	-6.41	DGG	-2.96	-3.56
TQL	-3.69	-4.29	XKT-L	-2.62	-3.22
YJQ-L	-4.69	-5.29	XKT-R	-4.81	-5.41
GMQ	-4.74	-5.34	ZTH	-3.31	-3.90
HTJ-L	-4.89	-5.49	HMZ	-2.33	-2.93
HTJ-R	-3.84	-4.43	HMZP-R	-4.44	-5.04

Table 5 Comparison of major chemical compositions of the Liuhuangtang and Zaotanghe hot springs

子区	数值类型	质量浓度/(μg·L^-1)		质量浓度/(mg·L^-1)
子区	数值类型	Hg	As	Cl	F	Br	Na	K	Ca	Mg	Li	Si	B
硫磺塘	最大值	1.472	1 059	738.1	19.9	2.35	858.0	150.0	2.13	0.32	9.90	152.0	12.01
硫磺塘	最小值	0.765	593	433.8	12.6	1.61	507.5	84.9	1.62	0.26	6.11	108.9	7.41
澡塘河	最大值	0.524	305	338.7	10.5	1.27	437.6	76.5	13.67	1.84	5.18	79.4	5.88
澡塘河	最小值	0.405	151	270.7	9.3	1.22	355.6	64.2	3.87	0.36	4.15	65.1	5.03

Fig.7 Spatial distribution of mercury contents in neutral hot springs and its relations to faults

References 25

[1]	KRABBENHOFT D P, SUNDERLAND E M. Global change and mercury[J]. Science, 2013, 341(6153):1457-1458. DOI URL
[2]	孙学军, 康世昌, 张强弓, 等. 山地冰川消融过程中汞的行为及环境效应综述[J]. 地球科学进展, 2017, 32(6):589-598.
[3]	NIMICK D A, CALDWELL R R, SKAAR D R, et al. Fate of geothermal mercury from Yellowstone National Park in the Madison and Missouri Rivers, USA[J]. Science of the Total Environment, 2013, 443:40-54. DOI URL
[4]	廖志杰, 赵平. 滇藏地热带: 地热资源和典型地热系统[M]. 北京: 科学出版社, 1999.
[5]	郭清海, 刘明亮, 李洁祥. 腾冲热海地热田高温热泉中的硫代砷化物及其地球化学成因[J]. 地球科学: 中国地质大学学报, 2017, 42(2):286-297.
[6]	庄亚芹, 郭清海, 刘明亮, 等. 高温富硫化物热泉中硫代砷化物存在形态的地球化学模拟: 以云南腾冲热海水热区为例[J]. 地球科学: 中国地质大学学报, 2016, 41(9):1499-1510.
[7]	GUO Q H, LIU M L, LI J X, et al. Acid hot springs discharged from the Rehai hydrothermal system of the Tengchong volcanic area (China): formed via magmatic fluid absorption or geothermal steam heating[J]. Bulletin of Volcanology, 2014, 76(10):1-12.
[8]	白登海, 廖志杰, 赵国泽, 等. 从 MT 探测结果推论腾冲热海热田的岩浆热源[J]. 科学通报, 1994, 39(4):344-347.
[9]	上官志冠. 腾冲热海地热田热储结构与岩浆热源的温度[J]. 岩石学报, 2000, 16(1):83-90.
[10]	上官志冠, 孙明良. 腾冲热海地区现代幔源岩浆气全释放特征[J]. 中国科学: D 辑, 2000, 30(4):407-414.
[11]	赵慈平. 腾冲火山区现代幔源氦释放特征及深部岩浆活动研究[D]. 北京: 中国地震局地质研究所, 2008.
[12]	赵慈平, 冉华, 陈坤华. 由相对地热梯度推断的腾冲火山区现存岩浆囊[J]. 岩石学报, 2006, 22(6):1517-1528.
[13]	BALL J W, MCCLESKEY R B, NORDSTROM D K. Water-chemistry data for selected springs, geysers, and streams in Yellowstone National Park, Wyoming, 2006-2008[R]. Open-File Report 2010-1192. Denver: US Geological Survey, 2010: 1-109.
[14]	BALL J W, MCCLESKEY R B, NORDSTROM D K, et al. Water-chemistry data for selected Springs, geysers, and streams in Yellowstone National Park, Wyoming, 2003-2005[R]. Open-File Report 2006-1339. Denver: US Geological Survey, 2006: 1-137.
[15]	MCCLESKEY R, CHIU R, NORDSTROM D, et al. Water-chemistry data for selected springs, geysers, and streams in Yellowstone National Park, Wyoming, Beginning 2009-sample information[R]. Denver: US Geological Survey, 2014: 1-135.
[16]	MCCLESKEY R B, BALL J W, NORDSTROM D K, et al. Water-chemistry data for selected hot springs, geysers and streams in Yellowstone National Park, Wyoming, 2001-2002[R]. Open-File Report 2004-1316. Denver: US Geological Survey, 2005: 1-94.
[17]	景世林, 李佐唐, 李彤起. 通渭温泉水汞映震能力的初步分析[J]. 高原地震, 1996(3):63-66.
[18]	李朝明, 杨志坚, 杨军, 等. 下关温泉水汞整点观测变化与日测值关系研究[J]. 地震地磁观测与研究, 2010, 31(6):64-69.
[19]	杨志坚, 李朝明. 滇西北地区活动构造温泉水汞背景值观测研究[J]. 地震地磁观测与研究, 2010, 31(5):138-141.
[20]	GUO Q H, WANG Y X. Geochemistry of hot springs in the Tengchong hydrothermal areas, Southwestern China[J]. Journal of Volcanology and Geothermal Research, 2012, 215:61-73.
[21]	GIGGENBACH W F. Geothermal solute equilibria. derivation of Na-K-Mg-Ca geoindicators[J]. Geochimica et Cosmochimica Acta, 1988, 52(12):2749-2765. DOI URL
[22]	GIGGENBACH W F, SOTO R C. Isotopic and chemical-composition of water and steam discharges from volcanic magmatic hydrothermal systems of the Guanacaste Geothermal Province, Costa Rica[J]. Applied Geochemistry, 1992, 7(4):309-332. DOI URL
[23]	GIGGENBACH W F. Magma degassing and mineral deposition in hydrothermal systems along convergent plate boundaries[J]. Society of Economic Geologists Special Publication, 2003, 10:1-18.
[24]	GUO Q H, PLANER-FRIEDRICH B, LIU M, et al. Arsenic and thioarsenic species in the hot springs of the Rehai magmatic geothermal system, Tengchong volcanic region, China[J]. Chemical Geology, 2017, 453:12-20. DOI URL
[25]	GUO Q H, PLANER-FRIEDRICH B, LIU M, et al. Magmatic fluid input explaining the geochemical anomaly of very high arsenic in some southern Tibetan geothermal waters[J]. Chemical Geology, 2019, 513:32-43. DOI URL