Inhibition of mercury release from forest soil by high atmospheric deposition of Ca²⁺ and SO₄²⁻.
As one of the most important natural mercury (Hg) sources, soil release (emission to the atmosphere or leaching to soil water) depends on various factors, some of which can be affected by atmospheric deposition. We studied the effect of flue gas desulfurization gypsum (FGDG) addition on soil Hg release in a Masson pine (Pinus massoniana) forest in southwestern China. FGDG addition simulated atmospheric deposition of Ca(2+), SO4(2-) and Hg, which are commonly high in China. Results showed that Hg concentration in soil water decreased with the gypsum treatment, suggesting that the mobility of Hg in mineral soil was reduced. Moreover, the application of gypsum also seems to have decreased Hg emission from the soil, shown by the lower Hg contents in leaf tissues of ground vegetation in the treated plots than in the reference. Both Hg mobility in the soil and Hg emission to the atmosphere were decreased despite the additional Hg input from FGDG. The decreased DOC concentration in soil water and the elevated organic sulfur content in the soil Oe & Oa horizons were speculated to result in an enhanced capacity of surface soil to bind Hg, and thus to reduce Hg release from the soil. However, with the increasingly stringent control of particulate matter (PM) and sulfur dioxide (SO2) emissions in China, the deposition of Ca(2+) and SO4(2-) is expected to decrease, and their ability to inhibit soil Hg release is likely to decline in the future.
State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Yao
Y
Luo
State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Collaborative Innovation Centre for Regional Environmental Quality, Tsinghua University, Beijing 100084, China. Electronic address: lduan@tsinghua.edu.cn.
Lei
L
Duan
Shenzhen Academy of Environment Sciences, Shenzhen 518001, China.
Guangyi
G
Xu
State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Collaborative Innovation Centre for Regional Environmental Quality, Tsinghua University, Beijing 100084, China.
Jiming
J
Hao
D001272:Atmosphere / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry*; D002681:China; D065928:Forests; D005740:Gases; D008628:Mercury / Q000032:analysis / Q000737:chemistry*; D052638:Particulate Matter / Q000737:chemistry*; D028223:Pinus; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*
D005740:Gases; D052638:Particulate Matter; D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D008628:Mercury; D002133:Calcium Sulfate
Atmospheric deposition; Flue gas desulfurization gypsum (FGDG); Forest soil; Mercury; Natural source; Organic sulfur