Mercury release flux and its influencing factors at the air-water interface in paddy field in Chongqing, China

Zhu, Jinshan; Wang, Dingyong; Ma, Ming

doi:10.1007/s11434-012-5412-8

Cited by 11 publications

(11 citation statements)

References 31 publications

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“…The diurnal pattern is caused by the variation of solar irradiance, close to zero at night and peaking from 13:00 to 15:00 (UTC + 8). Similar diurnal patterns have been observed during filed measurements for forest, grassland, and cropland in China (Feng et al, 2005;Fu et al, 2008Fu et al, , 2012Zhu et al, 2013). The degree of diurnal variability for each land use is highly related to the LAI.…”

Section: Type Descriptionsupporting

confidence: 72%

“…In addition, the datasets of terrestrial flux in mainland China recently reported in the literature allow verification of model results and optimization of model schemes. These field data of Hg 0 air-surface exchange in China document the flux characteristics over different land uses including urban-rural-remote differences and effects of crop rotation over agricultural lands (Fu et al, 2008(Fu et al, , 2010(Fu et al, , 2012(Fu et al, , 2013aZhu et al, 2011;Zhu et al, 2013;Zhu et al, 2016;Sommar et al, 2013aSommar et al, , b, 2016a.…”

Section: Introductionmentioning

confidence: 99%

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Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

et al. 2016

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Abstract. Mercury (Hg) emission from natural surfaces plays an important role in global Hg cycling. The present estimate of global natural emission has large uncertainty and remains unverified against field data, particularly for terrestrial surfaces. In this study, a mechanistic model is developed for estimating the emission of elemental mercury vapor (Hg0) from natural surfaces in China. The development implements recent advancements in the understanding of air–soil and air–foliage exchange of Hg0 and redox chemistry in soil and on surfaces, incorporates the effects of soil characteristics and land use changes by agricultural activities, and is examined through a systematic set of sensitivity simulations. Using the model, the net exchange of Hg0 between the atmosphere and natural surfaces of mainland China is estimated to be 465.1 Mg yr−1, including 565.5 Mg yr−1 from soil surfaces, 9.0 Mg yr−1 from water bodies, and −100.4 Mg yr−1 from vegetation. The air–surface exchange is strongly dependent on the land use and meteorology, with 9 % of net emission from forest ecosystems; 50 % from shrubland, savanna, and grassland; 33 % from cropland; and 8 % from other land uses. Given the large agricultural land area in China, farming activities play an important role on the air–surface exchange over farmland. Particularly, rice field shift from a net sink (3.3 Mg uptake) during April–October (rice planting) to a net source when the farmland is not flooded (November–March). Summing up the emission from each land use, more than half of the total emission occurs in summer (51 %), followed by spring (28 %), autumn (13 %), and winter (8 %). Model verification is accomplished using observational data of air–soil/air–water fluxes and Hg deposition through litterfall for forest ecosystems in China and Monte Carlo simulations. In contrast to the earlier estimate by Shetty et al. (2008) that reported large emission from vegetative surfaces using an evapotranspiration approach, the estimate in this study shows natural emissions are primarily from grassland and dry cropland. Such an emission pattern may alter the current understanding of Hg emission outflow from China as reported by Lin et al. (2010b) because a substantial natural Hg emission occurs in West China.

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Section: Type Descriptionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

et al. 2016

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“…GEM fluxes from different landscapes in cold seasons (from November to April) were relatively limited. Several studies found that GEM Fu et al (2007Fu et al ( , 2008Fu et al ( , 2010bFu et al ( , 2012cFu et al ( , 2013, Zhu et al (2011Zhu et al ( , 2013, Ma et al (2013), and Liu et al (2014) fluxes from dry farmland, forest soil, and lake waters were about 2.5-40 times (mean = 6.5, n = 18) lower than those in warm seasons Ma et al, 2013;Fu et al, 2010b;Fu et al, 2013). Given the different landscapes and seasonal patterns of GEM fluxes in mainland China, we estimate the annual natural GEM emissions to be 528 t in China.…”

Section: Estimates Of Gem Emissionsmentioning

confidence: 97%

Correlation slopes of GEM / CO, GEM / CO<sub>2</sub>, and GEM / CH<sub>4</sub> and estimated mercury emissions in China, South Asia, the Indochinese Peninsula, and Central Asia derived from observations in northwestern and southwestern China

Zhang

Lin

et al. 2015

Atmos. Chem. Phys.

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Abstract. Correlation analyses between atmospheric mercury (Hg) and other trace gases are useful for identification of sources and constraining regional Hg emissions. Emissions of Hg in Asia contribute significantly to the global budget of atmospheric Hg. However, due to the lack of reliable data on the source strength, large uncertainties remain in the emission inventories of Hg in Asia. In the present study, we calculated the correlation slopes of GEM / CO, GEM / CO 2 , and GEM / CH 4 for mainland China, South Asia, the Indochinese Peninsula, and Central Asia using the ground-based observations at three remote sites in northwestern and southwestern China, and applied these values to estimate GEM emissions in the four source regions. The geometric mean GEM / CO correlation slopes for mainland China, South Asia, the Indochinese Peninsula, and Central Asia were 7.3 ± 4.3, 7.8 ± 6.4, 7.8 ± 5.0, and 13.4 ± 9.5 pg m −3 ppb −1 , respectively, and values in the same source regions were 33.3 ± 30.4, 27.4 ± 31.0, 23.5 ± 15.3, and 20.5 ± 10.0 pg m −3 ppb −1 for the GEM / CH 4 correlation slopes, respectively. The geometric means of GEM / CO 2 correlation slopes for mainland China, South Asia, and Central Asia were 240 ± 119, 278 ± 164, 315 ± 289 pg m −3 ppm −1 , respectively. These values were the first reported correlation slopes of GEM / CO, GEM / CO 2 , and GEM / CH 4 in four important source regions of Asia, not including the GEM / CO ratios in mainland China. The correlation slopes of GEM / CO, GEM / CO 2 , and GEM / CH 4 in Asia were relatively higher than those observed in Europe, North America, and South Africa, which may highlight GEM emissions from nonferrous smelting, large-scale and artisanal mercury and gold production, natural sources, and historically deposited mercury (re-emission) in Asia. Using the observed GEM / CO and GEM / CO 2 slopes, and the recently reported emission inventories of CO and CO 2 , the annual GEM emissions in mainland China, South Asia, the Indochinese Peninsula, and Central Asia were estimated to be in the ranges of 1071-1187, 340-470, 125, and 54-90 t, respectively. The estimated quantity of GEM emissions from the GEM / CH 4 correlation slopes is significantly larger, which may be due to the larger uncertainties in CH 4 emissions in Asia as well as insufficient observations of GEM / CH 4 correlation slopes, therefore leading to an overestimate of GEM emissions. Our estimates of GEM emissions in the four Asian regions were significantly higher (3-4 times) than the anthropogenic GEM emissions reported in recent studies. This discrepancy could come from a combination of reasons including underestimates of anthropogenic and natural GEM emissions; large uncertainties related to CO, CO 2 , and CH 4 emission inventories; and inherent limitations of the correlation slope method.

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“…These limitations may also explain some discrepancies between the observed and model‐simulated rice THg and MeHg concentrations. In addition, J. S. Zhu et al () observed significant positive relationships between mercury evasion flux and solar radiation, and water temperature in Chinese rice paddies. The relationship between environmental factors and the rate of biogeochemical processes for mercury in rice paddies are, however, limited to a few studies and thus not considered in our model.…”

Section: Discussionmentioning

confidence: 97%

Present and Future Mercury Concentrations in Chinese Rice: Insights From Modeling

Kwon

Selin

Giang

et al. 2018

Global Biogeochemical Cycles

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We construct a rice paddy biogeochemical cycle model to investigate processes governing rice mercury sources and to understand factors influencing spatiotemporal variability in Chinese rice mercury concentrations. The rice paddy model takes atmospheric mercury deposition, simulated from a global atmospheric chemistry transport model (GEOS‐Chem), and soil and irrigable surface water mercury concentrations obtained from literature and calculates rice inorganic (IHg) and methylmercury (MeHg) concentrations. We use ranges of GEOS‐Chem‐simulated future atmospheric mercury deposition—no policy and strict policy to regulate mercury emissions from Chinese coal‐fired power plants under the Minamata Convention on Mercury—to simulate future rice IHg and MeHg concentrations. Sensitivity analyses suggest that rice IHg and MeHg concentrations are more sensitive to the process of soil desorption than infiltration of recently introduced mercury (atmospheric and irrigation source). The rate of internal methylation via microbial activity has the largest modeled influence on rice MeHg concentration. We find that soil mercury, rather than atmospheric deposition, explains observed spatial variability in rice IHg and MeHg concentrations and captures locations of rice mercury hot spots (>20 ng/g; China National Standard Limit). Under our future scenarios, the Chinese median rice IHg and MeHg concentration increases by 13% and decrease by 18% under no policy and strict policy, respectively. Regions with the largest percentage decline in rice IHg and MeHg concentrations under strict policy are in central China, which have high rice mercury concentrations, rice production, and consumption. Our study suggests that addressing Chinese rice mercury contamination requires attention to contaminated soil and regulation of anthropogenic mercury emissions.

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Mercury release flux and its influencing factors at the air-water interface in paddy field in Chongqing, China

Cited by 11 publications

References 31 publications

Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

Correlation slopes of GEM / CO, GEM / CO<sub>2</sub>, and GEM / CH<sub>4</sub> and estimated mercury emissions in China, South Asia, the Indochinese Peninsula, and Central Asia derived from observations in northwestern and southwestern China

Present and Future Mercury Concentrations in Chinese Rice: Insights From Modeling

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Mercury release flux and its influencing factors at the air-water interface in paddy field in Chongqing, China

Cited by 11 publications

References 31 publications

Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

Correlation slopes of GEM / CO, GEM / CO&lt;sub&gt;2&lt;/sub&gt;, and GEM / CH&lt;sub&gt;4&lt;/sub&gt; and estimated mercury emissions in China, South Asia, the Indochinese Peninsula, and Central Asia derived from observations in northwestern and southwestern China

Present and Future Mercury Concentrations in Chinese Rice: Insights From Modeling

Contact Info

Product

Resources

About

Correlation slopes of GEM / CO, GEM / CO<sub>2</sub>, and GEM / CH<sub>4</sub> and estimated mercury emissions in China, South Asia, the Indochinese Peninsula, and Central Asia derived from observations in northwestern and southwestern China