Mercury distribution in surface soil of China is potentially driven by precipitation, vegetation cover and organic matter

Abstract Background Mercury (Hg) distribution in surface soil in China is quite uneven with relatively high concentrations in southeastern China and low concentrations in northwestern China. The reason for this is inconclusive so far, especially on the continental scale. In the present study we used the multiple linear regression model to evaluate the relative importance of these different factors and elucidate the contribution on soil Hg of major factors, such as dry and wet precipitations, vegetation cover, soil organic matter and solar radiation. Results Wet and dry deposition associated with precipitation and vegetation cover, and emissions influenced by soil organic matter (SOM), are key factors controlling Hg distribution in surface soil. In southeast China, high wet deposition associated with south Asia monsoon and dry deposition, enhanced by vegetation canopies, together with low emission caused by high vegetated surface and solar radiation, are responsible for high Hg in soil (> 0.08 mg/kg). In northeast China, medium wet Hg deposition and high dry deposition via throughfall and litterfall, low emission due to weak solar radiation and high SOM are responsible for high Hg accumulation in soil. In northwest China, low wet deposition, together with high emission by low vegetation cover (bare soil), SOM and strong solar radiation contributed to low Hg in surface soil (< 0.03 mg/kg). Conclusions We suggest that wet deposition derived from Asian monsoon, dry deposition linked to vegetated surfaces and Hg emission associated with vegetation cover, SOM and solar radiation play key roles in Hg balance in other terrestrial environments worldwide, especially in those regions with significantly high wet and dry deposition and high vegetation cover.

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Mercury distribution in the surface soil of China is potentially driven by precipitation, vegetation cover and organic matter

10.21203/rs.3.rs-21590/v2 ◽

2020 ◽

Author(s):

Zhao-Yang Zhang ◽

Gang Li ◽

Lei Yang ◽

Xin-Jun Wang ◽

Guo-Xin Sun

Keyword(s):

Organic Matter ◽

Solar Radiation ◽

Dry Deposition ◽

Vegetation Cover ◽

Wet Deposition ◽

Surface Soil ◽

Southeastern China ◽

Low Levels ◽

Soil Hg ◽

Hg Accumulation

Abstract Background: Understanding the mechanism of Hg accumulation in soil, which is a net Hg sink, at a national scale is important to protecting the environment and improving food safety. The mercury (Hg) distribution in surface soil in China is quite uneven, with relatively high concentrations in southeastern China and low concentrations in northwestern China. The reason for this distribution is inconclusive, especially at the continental scale. In this study, the relative contributions of the key impact factors, including dry and wet deposition, soil organic matter (SOM) and solar radiation to soil Hg, were evaluated.Results: Wet and dry deposition associated with precipitation and vegetation cover and emissions influenced by SOM are key factors controlling Hg distribution in surface soil. In southeastern China, high levels of wet deposition associated with the South Asia monsoon and dry deposition, enhanced by vegetation canopies, together with low levels of emissions caused by highly vegetated surfaces and solar radiation, are responsible for the high Hg levels in soil (>0.08 mg/kg). In northeastern China, moderate levels of wet Hg deposition, high levels of dry deposition via throughfall and litterfall, low emissions due to weak solar radiation and high levels of SOM are responsible for high Hg accumulation in soil. In northwestern China, low levels of wet deposition, together with high emissions levels, low vegetation cover (bare soil) and SOM and strong solar radiation, contributed to the low Hg level in the surface soil (<0.03 mg/kg).Conclusions: We suggest that wet deposition derived from the Asian monsoon, dry deposition linked to vegetated surfaces and Hg emissions associated with vegetation cover, SOM and solar radiation play key roles in the soil Hg level in China. In other terrestrial environments worldwide, especially in regions with significantly high levels of wet deposition and high amounts of vegetation cover and soil SOM, high Hg concentrations may exist in surface soil.

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Soil stripping and replacement for the rehabilitation of bauxite-mined land at Weipa. I. Initial changes to soil organic matter and related parameters

Soil Research ◽

10.1071/sr99043 ◽

2000 ◽

Vol 38 (2) ◽

pp. 345 ◽

Cited By ~ 18

Author(s):

G. D. Schwenke ◽

D. R. Mulligan ◽

L. C. Bell

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Field Experiments ◽

Surface Soil ◽

Soil Disturbance ◽

Microbial Biomass C ◽

Low Grade ◽

Double Pass ◽

Organic C ◽

The Difference

At Weipa, in Queensland, Australia, sown tree and shrub species sometimes fail to establish on bauxite-mined land, possibly because surface-soil organic matter declines during soil stripping and replacement. We devised 2 field experiments to investigate the links between soil rehabilitation operations, organic matter decline, and revegetation failure. Experiment 1 compared two routinely practiced operations, dual-strip (DS) and stockpile soil, with double-pass (DP), an alternative method, and subsoil only, an occasional result of the DS operation. Other treatments included variations in stripping-time, ripping-time, fertiliser rate, and cultivation. Dilution of topsoil with subsoil, low-grade bauxite, and ironstone accounted for the 46% decline of surface-soil (0–10 cm) organic C in DS compared with pre-strip soil. In contrast, organic C in the surface-soil (0–10 cm) of DP plots (25.0 t/ha) closely resembled the pre-strip area (28.6 t/ha). However, profile (0–60 cm) organic C did not differ between DS (91.5 t/ha), DP (107 t/ha), and pre-strip soil (89.9 t/ha). Eighteen months after plots were sown with native vegetation, surface-soil (0–10 cm) organic C had declined by an average of 9% across all plots. In Experiment 2, we measured the potential for post-rehabilitation decline of organic matter in hand-stripped and replaced soil columns that simulated the DS operation. Soils were incubated in situ without organic inputs. After 1 year’s incubation, organic C had declined by up to 26% and microbial biomass C by up to 61%. The difference in organic C decline between vegetated replaced soils (Expt 1) and bare replaced soils (Expt 2) showed that organic inputs affect levels of organic matter more than soil disturbance. Where topsoil was replaced at the top of the profile (DP) and not ploughed, inputs from volunteer native grasses balanced oxidation losses and organic C levels did not decline.

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Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

10.5194/acp-2017-1071 ◽

2018 ◽

Author(s):

David M. Nelson ◽

Urumu Tsunogai ◽

Ding Dong ◽

Takuya Ohyama ◽

Daisuke D. Komatsu ◽

...

Keyword(s):

Dry Deposition ◽

Wet Deposition ◽

Urban Environments ◽

Rural Site ◽

Urban Site ◽

Peroxy Radicals ◽

Long Distance ◽

Wet And Dry Deposition ◽

Atmospheric Nitrate ◽

Nitrate Deposition

Abstract. Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or come from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ~ +22 and +30 ‰ with higher values during winter and lower values in summer, which suggests greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19–+25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet deposition in urban environments and wet and dry deposition in rural environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet deposition, which is transported longer distances. These results illustrate the value of stable isotope data for distinguishing the transport distances and reaction pathways of atmospheric nitrate pollution.

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Recent updates to the atmospheric aerosol modelling of the ECMWF IFS in support to CAMS

10.5194/egusphere-egu21-14367 ◽

2021 ◽

Author(s):

Samuel Remy ◽

Zak Kipling ◽

Vincent Huijnen ◽

Johannes Flemming ◽

Swen Metzger ◽

...

Keyword(s):

Organic Matter ◽

Dry Deposition ◽

Wet Deposition ◽

Deposition Velocity ◽

Surface Concentration ◽

Atmospheric Composition ◽

Small Scale ◽

Skill Scores ◽

Simulated Surface ◽

The Impact

The Integrated Forecasting System (IFS) of ECMWF is used within the Copernicus Atmosphere Monitoring Service (CAMS) to provide global analyses and forecasts of atmospheric composition, including aerosols as well as reactive trace gases and greenhouse gases.The aerosol model of the IFS, IFS-AER, is a simple sectional-bulk scheme that forecasts seven species: &#160;dust, sea-salt, black carbon, organic matter, sulfate, and &#160;since July 2019, nitrate and ammonium. &#160;The main developments that have been recently carried out, tested and are now contemplated for implementation in the next operational version (known as cycle 48r1) are presented here.The dry deposition velocities are computed as a function of roughness length, particle size and surface friction velocity, while wet deposition depends mainly on the precipitation fluxes. The parameterizations of both dry and wet deposition have been upgraded with more recent schemes, which have been shown to improve the simulated deposition fluxes for several aerosol species. The impact of this upgrade on the skill scores of simulated aerosol optical depth (AOD) and surface particulate matter concentrations against a range of observations is very positive.The simulated surface concentration of nitrate and ammonium are frequently strongly overestimated over Europe and the &#160;United States in the current version of the IFS. Nitrate, ammonium, and their precursors nitric acid and ammonia, were evaluated against a range of ground and remote data and it was found that the recently-implemented gas-particle partitioning scheme is too efficient in producing nitrate and ammonium particles.A series of small-scale changes, such as adjusting nitrate dry deposition velocity, direct particulate sulphate emission, and limiting nitrate/ammonium production by the concentration of mineral cations, have been implemented and shown to be effective in improving the simulated surface concentration of &#160;nitrate and ammonium.The representation of secondary organic aerosol (SOA) in the IFS has been overhauled with the introduction of a new SOA species, distinct from primary organic matter, with anthropogenic and biogenic components. The implementation of this new species leads to a significant improvement of the simulated surface concentration of organic carbon. An evaluation of simulated SOA concentrations at the surface against climatological values derived from observations using Positive Matrix Factorisation (PMF) techniques also shows a reasonable agreement.

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Seasonal variations in black and organic carbon wet and dry deposition rates at SMEAR III station (60oN), Finland

10.5194/egusphere-egu21-5362 ◽

2021 ◽

Author(s):

Outi Meinander ◽

Enna Heikkinen ◽

Jonas Svensson ◽

Minna Aurela ◽

Aki Virkkula ◽

...

Keyword(s):

Organic Carbon ◽

Black Carbon ◽

Dry Deposition ◽

Wet Deposition ◽

Total Carbon ◽

Sampling Location ◽

Atmospheric Measurements ◽

Deposition Rates ◽

Wet And Dry Deposition ◽

Custom Made

Black carbon (BC) and organic carbon (OC, including brown carbon BrC) aerosols in the atmosphere, and their wet and dry deposition, are important for their climatic and cryospheric effects. Seemingly small amounts of BC in snow, of the order of 10&#8211;100 parts per billion by mass (ppb), have been shown to decrease its albedo by 1&#8211;5 %. Due to the albedo-feedback mechanism, surface darkening accelerates snow and ice melt. In snow, the temporal variability of light absorbing aerosols, such as BC, depends both on atmospheric and cryospheric processes, mostly on sources and atmospheric transport, and dry and wet deposition processes, as well as post-depositional snow processes.We started a new research activity on BC and OC wet and dry deposition at Helsinki Kumpula SMEAR III station (60&#176;12 N, 24&#176;57 E, Station for Measuring Ecosystem-Atmosphere Relations, https://www.atm.helsinki.fi/SMEAR/index.php/smear-iii). The work included winter, spring, summer and autumn deposition samples during January 2019 - June 2020 (sampling is currently on hold). In winter, wet deposition consisted of snowfall and rainwater samples. Dry deposition samples were separately collected in 2020. For sample collection, a custom-made device, including a heating-system, was applied. The samples were analyzed using the OCEC analyzer of the Finnish Meteorological Institute&#8217;s aerosol laboratory, Helsinki, Finland. The special features in our deposition data are:&#160;<ul><li>seasonal BC, OC, and TC (total carbon, the sum of BC and OC) deposition data for an urban background station at 60 oN</li> <li>precipitation received as either water or snow &#160;</li> <li>dry deposition samples included (only in 2020)</li> <li>data as wet and dry deposition rates [concentration/time/area]</li> <li>simultaneous atmospheric measurements of the SMEAR III station</li> </ul>Since our deposition samples are collected manually, the data are non-continuous, yet they allow us to provide deposition rates. Such data can be utilized in various modeling approaches including, for example, climate and long-range transport and deposition modeling. According to our knowledge, these data are the first BC (determined as elemental carbon, EC), OC and TC wet and dry deposition data to represent Finland. Our sampling location, north of 60 deg. N, can be useful for other high-latitude studies and Arctic assessments, too.Acknowledgements. We gratefully acknowledge support from the Academy of Finland NABCEA-project of Novel Assessment of Black Carbon in the Eurasian Arctic (no. 296302) and the Academy of Finland Flagship funding (grant no. 337552).

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Warming alters surface soil organic matter composition despite unchanged carbon stocks in a Tibetan permafrost ecosystem

Functional Ecology ◽

10.1111/1365-2435.13489 ◽

2020 ◽

Vol 34 (4) ◽

pp. 911-922 ◽

Cited By ~ 3

Author(s):

Fei Li ◽

Yunfeng Peng ◽

Leiyi Chen ◽

Guibiao Yang ◽

Benjamin W. Abbott ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Surface Soil ◽

Carbon Stocks ◽

Organic Matter Composition ◽

Soil Organic Matter Composition

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Estimation of surface soil organic matter using a ground-based active sensor and aerial imagery

Precision Agriculture ◽

10.1007/s11119-010-9158-5 ◽

2010 ◽

Vol 12 (1) ◽

pp. 82-102 ◽

Cited By ~ 11

Author(s):

D. F. Roberts ◽

V. I. Adamchuk ◽

J. F. Shanahan ◽

R. B. Ferguson ◽

J. S. Schepers

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Surface Soil ◽

Aerial Imagery ◽

Active Sensor

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Atmospheric total gaseous mercury (TGM) concentrations and wet and dry deposition of mercury at a high-altitude mountain peak in south China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-23465-2009 ◽

2009 ◽

Vol 9 (6) ◽

pp. 23465-23504 ◽

Cited By ~ 11

Author(s):

X. W. Fu ◽

X. Feng ◽

Z. Q. Dong ◽

R. S. Yin ◽

J. X. Wang ◽

...

Keyword(s):

South China ◽

Dry Deposition ◽

Urban Areas ◽

Wet Deposition ◽

Ambient Air ◽

Total Gaseous Mercury ◽

Deposition Fluxes ◽

Wet And Dry Deposition ◽

Gaseous Mercury ◽

Seasonal And Diurnal Variations

Abstract. China is regarded as the largest contributor of mercury (Hg) to the global atmospheric Hg budget. However, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric total gaseous mercury (TGM) were carried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Wet and dry deposition fluxes of Hg were also calculated following collection of precipitation, throughfall and litterfall. Atmospheric TGM concentrations averaged 2.80±1.51 ng m−3, which was highly elevated compared to global background values but much lower than semi-rural and industrial/urban areas in China, indicating great emissions of Hg in central, south and southwest China. Seasonal and diurnal variations of TGM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Wet deposition of Hg was quite low, while its dry deposition of Hg (litterfall + throughfall-direct wet deposition) constituted a major portion of total deposition (~88% for total mercury (THg) and 84% for methyl mercury (MeHg)). This highlights the importance of vegetation to Hg atmospheric cycling. In a remote forest ecosystem of China, dry deposition of TGM, especially gaseous elemental mercury (GEM), was very important for the depletion of atmospheric Hg. Elevated TGM level in ambient air may accelerate the foliar uptake of Hg through air which may partly explain the elevated Hg dry deposition fluxes observed in Mt. Leigong.

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Key predictors of soil organic matter vulnerability to mineralization differ with depth at a continental scale

Biogeochemistry ◽

10.1007/s10533-021-00856-x ◽

2021 ◽

Author(s):

Tyler L. Weiglein ◽

Brian D. Strahm ◽

Maggie M. Bowman ◽

Adrian C. Gallo ◽

Jeff A. Hatten ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Field Capacity ◽

Climate Feedbacks ◽

Organic C ◽

Continental Scale ◽

Broad Array ◽

The Relationship ◽

Boruta Algorithm ◽

Som Decomposition

AbstractSoil organic matter (SOM) is the largest terrestrial pool of organic carbon, and potential carbon-climate feedbacks involving SOM decomposition could exacerbate anthropogenic climate change. However, our understanding of the controls on SOM mineralization is still incomplete, and as such, our ability to predict carbon-climate feedbacks is limited. To improve our understanding of controls on SOM decomposition, A and upper B horizon soil samples from 26 National Ecological Observatory Network (NEON) sites spanning the conterminous U.S. were incubated for 52 weeks under conditions representing site-specific mean summer temperature and sample-specific field capacity (−33 kPa) water potential. Cumulative carbon dioxide respired was periodically measured and normalized by soil organic C content to calculate cumulative specific respiration (CSR), a metric of SOM vulnerability to mineralization. The Boruta algorithm, a feature selection algorithm, was used to select important predictors of CSR from 159 variables. A diverse suite of predictors was selected (12 for A horizons, 7 for B horizons) with predictors falling into three categories corresponding to SOM chemistry, reactive Fe and Al phases, and site moisture availability. The relationship between SOM chemistry predictors and CSR was complex, while sites that had greater concentrations of reactive Fe and Al phases or were wetter had lower CSR. Only three predictors were selected for both horizon types, suggesting dominant controls on SOM decomposition differ by horizon. Our findings contribute to the emerging consensus that a broad array of controls regulates SOM decomposition at large scales and highlight the need to consider changing controls with depth.

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Soil organic matter relationships with the geotechnical-hydrological parameters, mineralogy and vegetation cover of hillslope deposits in Tuscany (Italy)

Bulletin of Engineering Geology and the Environment ◽

10.1007/s10064-020-01819-6 ◽

2020 ◽

Vol 79 (8) ◽

pp. 4005-4020 ◽

Cited By ~ 1

Author(s):

Elena Benedetta Masi ◽

Gabriele Bicocchi ◽

Filippo Catani

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Vegetation Cover ◽

Central Italy ◽

Mineralogical Composition ◽

Friction Angle ◽

Unit Weight ◽

Geotechnical Parameters ◽

Main Fraction ◽

Index Unit

Abstract Soil organic matter (SOM) represents a main fraction of superficial soil characterized by a mechanical-hydrological behaviour different from that of the inorganic fractions. In this study, a method to measure the SOM content was applied to 27 selected sites in Tuscany (central Italy) characterized by the presence of soil types common in the region: cambisols and regosols. The method included the contribution from root fragments, which is a fraction often neglected or underestimated in measurements, in the overall estimate of the SOM content. The retrieved SOM contents were analysed considering the vegetation cover at the sites and the selected attributes of geological interest, such as geotechnical parameters and the mineralogical composition of the soils. The SOM normalized to the bulk samples ranges between 1.8 and 8.9% by weight, with the highest values of the SOM content being associated with vegetation cover classes of forest and woodlands without shrubs. The SOM values showed close relationships with the abundance of the finer fractions (silt and clay) of the soil samples, and considering the relations with geotechnical properties, moderate correlations were found with the plasticity index, unit weight and effective friction angle, overall demonstrating the importance of considering SOM when the geotechnical and hydrological properties of soils are evaluated.

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