Total Hg and Hg isotopes in soils, street dust, and lake sediment around a large scale Zinc smelter in Hunan, China

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1 Total Hg and Hg isotopes in soils, street dust, and lake sediment around a large scale Zinc smelter in Hunan, China Zhonggen Li 1, Runsheng Yin 1, Ben Yu 1, Yan Lin 2, Guanghui Li 1, Chunhao Gu 1, Guangle Qiu 1, Xinbin Feng 1, Thorjørn Larssen 2 1. Institute of Geochemistry, CAS, Guiyang , China; 2. Norwegian Institute for Water Research, Oslo 0349, Norway SLU, Uppsala, Sweden May 21, 2014

2 Outline About the large scale smelter Hg in soils Hg in street dust Hg in lake sediment

3 Outline About the large scale smelter Hg in soils Hg in street dust Hg in lake sediment

4 Study area 盘县大田边煤矿 Zinc output (t/yr) 桐梓花秋二矿 The largest zinc smelter in China, Started into operation since late 1950s Zn ingot output: 0.50 Mt/yr Pb ingot output: 0.10 Mt/yr

5 Process of the large-scale zinc smelter Zhuzhou smelter Production procedure Zn ore sources Over 80 mines The hydrometallurgical process (electrolysis process) for zinc production: (1) Roasting ( C): Most Hg (2) Electrolysis process : Leaching, purification, electrolysis, melting and casting

6 Historical air pollution control measures Metal productions (tons) Phase 1 Dust collector Phase 2 Dust collector +acid production Phase 3 Dust collector +acid production + Hg reclaim tower Calendar year Zn Pb Time series of Zn and Pb output; with flue gas control techniques in different times

7 Historical pollution control measures Hg reclaim tower 105 t Hg was lost into atmosphere during Wu et al., STOTEN, 2014 Wang et al., Environ. Pollut., 2010

8 Outline About the large scale smelter Hg in soils Hg in street dust Hg in lake sediment

9 Soil sampling sites Totally 11 sampling areas, within 38 km to the smelter Agricultural soils Surface soil (0-20cm) Soil cores (0-50cm) Total Hg Smelter A D Hg isotope

10 Analysis for total Hg Total Hg: LUMEX direct Hg analyzer (RA-915+ & PYRO-915)

11 Analysis for Hg isotopes Apex-Q nebulizer HGX-200 Hydride generation system peristaltic pump On-line introduction systems Instrumentation (MC-ICP-MS, Nu Instruments, Nu plasma model)

12 Analysis for total Hg and Hg isotopes Mass dependent fractionation (MDF): Where xxx is 199, 200, 201, 202 Mass independent fractionation (MIF):

13 Total Hg in surface soil and soil cores f Surface soil (0-20cm) Hg Hg content in soil (mg kg -1 ) d e bc d de c Chinese soil quality criterior (GB ) mg/kg bc ab a a Soil profile 0.0 A B C D E F G H I J K BG Sampling area Li ZG et al., Appl. Geochem Hg contamination decreased with distance to the smelter and soil depth, the maximum Hg content is about 2.8 mg/kg (with background of 0.1 mg/kg), and the most impacted zone is the upper 20 cm soil layer (cultivated horizon), around 6.5 t Hg was accumulated in the soils within 4 km to the smelter

14 Hg isotopes in soils Hg ( ) Y= X R 2 =0.835 δ 202 Hg( ) is a function of Hg content in soils, and a binary mixingmodel can be built up /Hg (mg/kg)

15 Hg isotopes in soils 199 Hg( ) Hg( ) MIF: very small or insignificant

16 Hg isotopes in soils Depth (cm) Soil profile D Soil profile A Soil profile Heavier in the upper layer Lighter in the lower layer Hg( )

17 Outline About the large scale smelter Hg in soils Hg in street dust Hg in lake sediment

18 Sampling sites 55 sites within an area of 100 km 2 Smelter Total Hg Hg isotope

19 Total mercury in the street dust Li ZG et al., Environ. Pollut Maximum Hg content is 15 mg/kg in the street dust, and most affected area is the nearest 5 km

20 Hg isotopes in the street dust Hg( ) Hg( ) /Hg (mg/kg) Hg( ) δ 202 Hg : 0 ~ The relation between δ 202 Hg and mercury content is not clear (more sources?)

21 Outline About the large scale smelter Hg in soils Hg in street dust Hg in lake sediment

22 Sampling sites

23 Hg, Pb, Zn in sediment cores Depth (cm) SYH Hg (mg/kg) SYH#1 core Hg Pb Zn Depth (cm) GZ Hg (mg/kg) GZ core Hg Pb Zn Pb (mg/kg) Zn (mg/kg) Pb (mg/kg) Zn (mg/kg) Lakes that mainly affected by the Zn smelter Lake that mainly affected by the artisanal and small-scale gold mining (ASGM)

24 Hg isotopes in the sediment 202 Hg ( ) ASGM Zinc smelting liquid Hg (Laffont et al., EST,2009) ZnS ore concentrates (Estrad, EST, 2011) SYH CM DJ GZ Natural source /Hg *1000 Hg isotopes in the sediment

25 Source apportionment 1.0 Anthropogenic source Natural source 0.8 Contribution % of Hg in sediment is attributed to the human activities 0.0 Anthropenic contribution: SYH#1 CM#1 DJ Sample GZ 0.70

26 Summary (1)Total Hg in agricultural soil and street dust is decreasing with distance to the Zn smelter. (2)MDF (δ 202 Hg) is a function of soil Hg, while MIF (Δ 199 Hg) is negligible. (3)Two distance sources in lake sediment, Zn smelting and ASGM, can be found.

27 Study plan Collaborate with Swedish researches in two areas: (1) Mercury isotopic signatures in seriously contaminated aquatic sediments (or soils) with different sources (such as paper pulp, chlor-alkali, Zn & gold extraction and smelting) ; (2) Hg deposition flux and sources in less-impacted or remote lake sediment.

28 Thank you for your attention!