Pop-up English-Chinese

Mercury dynamics and mass balance in a subtropical forest in Southwest China

MA Ming1 LAI Da-kun2 SUN Tao1 YANG Guang1 WANG Ding-yong1,3

(1.Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing, China 400715)
(2.Simian Mountain Forest Resources Administration, Chongqing, China 402296)
(3.Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing, China 400716)

【Abstract】Forest ecosystem plays an important role in the geochemical cycle of mercury, but it is still not clear which compartment is the major source or sink for mercury cycling in the forest ecosystem. Simian Mountain was selected in our study because it had a subtropical monsoon climate and abundant precipitation ranging from 1 023 mm to 1 586 mm, which is beneficial to the growth of forest vegetation. Moreover, the evergreen broad-leaf forest in Mt. Simian is the most representative vegetation type preserved in the study reserve. Therefore, the input and output of mercury in this forest was monitored for one year. Results showed that THg and TMeHg concentrations in the precipitation were (11.23 ± 2.6) ng/L and (0.35 ± 0.24) ng/L respectively, which were higher than the global background values, probably due to the anthropogenic mercury pollution from ambient cities. The throughfall had higher mercury concentrations than precipitation, which was probably because the precipitation scoured the mercury settled in the canopies by dry deposition. THg concentration [(4.5 ± 2.0) ng/L] in the forest runoff decreased remarkably compared with that in the precipitation, which confirmed that the forest ecosystem had strong interception and fixation effect on mercury from precipitation. The main input pathway of mercury in the forest ecosystem was through litter, because atmospheric mercury can be absorbed by tree leaves. Moreover, when the tree leaves fell on the ground, the mercury in litter was released to the soil during its decomposition. Finally, this part of mercury was accumulated in the top soil due to the high concentrations of dissolved organic matter, leading to higher THg concentration in the top soil. Mercury emitted from the surface forest ground was the main way of output in this forest, which was affected by solar radiation, temperature, mercury concentration in top soil, soil moisture and so on. For the studied forest ecological system, the total amount of mercury input was greater than its total output, so it acted as a “sink” in the biogeochemical mercury cycle.

【Keywords】 mercury; methylmercury; forest ecosystem; Simian Mountain; output/input;

【DOI】

【Funds】 National Basic Research Program of China (2013CB430003) National Natural Science Foundation of China (41573105, 41173116) Chongqing Natural Science Foundation (cstc2016jcyjA1643)

Download this article

    References

    [1] Feng X, Jiang H, Qiu G, et al. Mercury mass balance study in Wujiangdu and Dongfeng reservoirs, Guizhou, China [J]. Environmental Pollution, 2009, 157(10): 2594–2603.

    [2] Feng X, Jiang H, Qiu G, et al. Geochemical processes of mercury in Wujiangdu and Dongfeng reservoirs, Guizhou, China [J]. Environmental Pollution, 2009, 157(11): 2970–2984.

    [3] Ma M, Wang D, Du H, et al. Mercury dynamics and mass balance in a subtropical forest, southwestern China [J]. Atmospheric Chemistry and Physics, 2016, 16(7): 4529–4537.

    [4] Wang X, Luo J, Yin R, et al. Using Mercury Isotopes to Understand Mercury Accumulation in the Montane Forest Floor of the Eastern Tibetan Plateau [J]. Environmental Science and Technology, 2016, 51(2): 801–809.

    [5] Fu X, Feng X, Shang L, et al. Two years of measurements of atmospheric total gaseous mercury (TGM) at a remote site in Mt. Changbai area, Northeastern China [J]. Atmospheric Chemistry and Physics, 2012, 12(9): 4215–4226.

    [6] Huang J, Kang S, Zhang Q, et al. Atmospheric deposition of trace elements recorded in snow from the Mt. Nyainqêntanglha region, southern Tibetan Plateau [J]. Chemosphere, 2013, 92(8): 871–881.

    [7] Yu B, Fu X, Yin R, et al. Isotopic composition of atmospheric mercury in China: new evidence for sources and transformation processes in air and in vegetation [J]. Environmental Science and Technology, 2016, 50(17): 9262–9269.

    [8] Sigler J M, Mao H, Talbot R. Gaseous elemental and reactive mercury in southern New Hampshire [J]. Atmospheric Chemistry and Physics, 2008, 9(6): 1929–1942.

    [9] Blackwell B D, Driscoll C T. Deposition of mercury in forests along a montane elevation gradient [J]. Environmental Science and Technology, 2015, 49(9): 5363–5370.

    [10] Blackwell B D, Driscoll C T, Maxwell J A, et al. Changing climate alters inputs and pathways of mercury deposition to forested ecosystems [J]. Biogeochemistry, 2014, 119(1–3): 215–228.

    [11] Laacouri A, Nater E A, Kolka R K. Distribution and uptake dynamics of mercury in leaves of common deciduous tree species in Minnesota, USA [J]. Environmental Science and Technology, 2013, 47(18): 10462–10470.

    [12] Stamenkovic J, Gustin M S. Nonstomatal versus stomatal uptake of atmospheric mercury [J]. Environmental Science & Technology, 2009, 43(5): 1367–1372.

    [13] Epa U. Method 1631, Revision E: Mercury in water by oxidation, purge and trap, and cold vapor atomic fluorescence spectrometry [S]. US Environmental Protection Agency Washington, DC, 2002.

    [14] Epa U. Method 1630, Methyl mercury in water by distillation, aqueous ethylation, purge and trap, and CVAFS [S]. US Environmental Protection Agency, Washington, DC, 1998.

    [15] Jiang H, Feng X, Liang L, et al. Determination of methyl mercury in waters by distillation-GC-CVAFS technique [J]. China Environmental Science, 2004, 24(5): 568–571 (in Chinese).

    [16] Guo Y, Feng X, Li Z, et al. Distribution and wet deposition fluxes of total and methyl mercury in Wujiang River Basin, Guizhou, China [J]. Atmospheric Environment, 2008, 42(30): 7096–7103.

    [17] Wang Y, Wang D, Meng B, et al. Spatial and temporal distributions of total and methyl mercury in precipitation in core urban areas, Chongqing, China [J]. Atmospheric Chemistry and Physics, 2012, 12(20): 9417–9426.

    [18] Rudd J W M. Sources of methyl mercury to freshwater ecosystems: A review [J]. Water, Air and Soil Pollution, 1995, 80(1): 697–713.

    [19] Downs S G, Macleod C L, Lester J N. Mercuty in Precipitation and Its Relation to Bioaccumulation in Fish: A Literature Review [J]. Water, Air and Soil Pollution, 1998, 108(1): 149–187.

    [20] Gårdfeldt K, Munthe J, Stromburg D, et al. A kinetic study on the abiotic methylation of divalent mercury in the aqueous phase [J]. The Science of the Total Environment, 2003, 304(1–3): 127–136.

    [21] Melendez-Perez J J, Fostier A H, Carvalho J A, et al. Soil and biomass mercury emissions during a prescribed fire in the Amazonian rain forest [J]. Atmospheric Environment, 2014, 96: 415–422.

    [22] Schlüter K. Review: evaporation of mercury from soils. An integration and synthesis of current knowledge [J]. Environmental Geology, 2000, 39(3/4): 249–271.

    [23] Skyllberg U, Xia K, Bloom P R, et al. Binding of mercury (II) to reduced sulfur in soil organic matter along upland-peat soil transects [J]. Journal of environmental quality, 2000, 29(3): 855–865.

    [24] Lu J Y, Schroeder W H, Berg T, et al. A device for sampling and determination of total particulate mercury in ambient air [J]. Analytical Chemistry, 1998, 70(11): 2403–2408.

    [25] Almeida M D, Marins R V, Paraquetti H H, et al. Mercury degassing from forested and open field soils in Rondônia, Western Amazon, Brazil [J]. Chemosphere, 2009, 77(1): 60–66.

    [26] Feng X, Yan H, Wang S, et al. Seasonal variation of gaseous mercury exchange rate between air and water surface over Baihua reservoir, Guizhou, China [J]. Atmospheric Environment, 2004, 38(28): 4721–4732.

    [27] Silva-Filho E V, Machado W, Oliveira R R, et al. Mercury deposition through litterfall in an Atlantic Forest at Ilha Grande, Southeast Brazil [J]. Chemosphere, 2006, 65(11): 2477–2484.

    [28] Ci Z, Peng F, Xue X, et al. Air–surface exchange of gaseous mercury over permafrost soil: an investigation at a high-altitude (4700m asl) and remote site in the central Qinghai-Tibet Plateau [J]. Atmospheric Chemistry and Physics, 2016, 16(22): 14741–14754.

    [29] Zhang C, He L, Wang D, et al. Soil/air interface mercury exchange fluxes of several ground surface in Chongqing [J]. Acta Scientiae Circumstantiae, 2005, 25(8): 1085–1090 (in Chinese).

This Article

ISSN:1000-6923

CN:11-2201/X

Vol 37, No. 12, Pages 4744-4750

December 2017

Downloads:0

Share
Article Outline

Abstract

  • 1 Study area
  • 2 Materials and methods
  • 3 Results and analyses
  • 4 Conclusions
  • References