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

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.

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

2020 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Gang Li ◽  
Lei Yang ◽  
Guo-Xin Sun
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Solar Radiation ◽  
Dry Deposition ◽  
Vegetation Cover ◽  
Wet Deposition ◽  
Surface Soil ◽  
Wet And Dry Deposition ◽  
Continental Scale ◽  
Low Emission

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.

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

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

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;The aerosol model of the IFS, IFS-AER, is a simple sectional-bulk scheme that forecasts seven species: &amp;#160;dust, sea-salt, black carbon, organic matter, sulfate, and &amp;#160;since July 2019, nitrate and ammonium. &amp;#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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;The simulated surface concentration of nitrate and ammonium are frequently strongly overestimated over Europe and the &amp;#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.&lt;/p&gt;&lt;p&gt;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 &amp;#160;nitrate and ammonium.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;

Earth’s Middle Ages: What Came after the GOE

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Middle Ages ◽  
Atmospheric Oxygen ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Dissolved Iron ◽  
Great Oxidation Event ◽  
Low Levels ◽  
Substantial Rise

This chapter considers the aftermath of the great oxidation event (GOE). It suggests that there was a substantial rise in oxygen defining the GOE, which may, in turn have led to the Lomagundi isotope excursion, which was associated with high rates of organic matter burial and perhaps even higher concentrations of oxygen. This excursion was soon followed by a crash in oxygen to very low levels and a return to banded iron formation deposition. When the massive amounts of organic carbon buried during the excursion were brought into the weathering environment, they would have represented a huge oxygen sink, drawing down levels of atmospheric oxygen. There appeared to be a veritable seesaw in oxygen concentrations, apparently triggered initially by the GOE. The GOE did not produce enough oxygen to oxygenate the oceans. Dissolved iron was removed from the oceans not by reaction with oxygen but rather by reaction with sulfide. Thus, the deep oceans remained anoxic and became rich in sulfide, instead of becoming well oxygenated.

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 ◽  
2000 ◽  
Vol 38 (2) ◽  
pp. 345 ◽  
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.

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

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.

Dry deposition of ammonia gas drives species change faster than wet deposition of ammonium ions: evidence from a long-term field manipulation

2011 ◽  
Vol 17 (12) ◽  
pp. 3589-3607 ◽  
Author(s):  
Lucy J. Sheppard ◽  
Ian D. Leith ◽  
Toshie Mizunuma ◽  
John Neil Cape ◽  
Alan Crossley ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Wet Deposition ◽  
Ammonium Ions ◽  
Ammonia Gas ◽  
Species Change ◽  
Field Manipulation ◽  
Term Field

scholarly journals Characteristics of atmospheric mercury deposition and size-fractionated particulate mercury in urban Nanjing, China

2014 ◽  
Vol 14 (5) ◽  
pp. 2233-2244 ◽  
Author(s):  
J. Zhu ◽  
T. Wang ◽  
R. Talbot ◽  
H. Mao ◽  
X. Yang ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Wet Deposition ◽  
Fine Particles ◽  
Unit Area ◽  
Atmospheric Mercury ◽  
Anthropogenic Sources ◽  
Deposition Flux ◽  
Coarse Particles ◽  
Mercury Deposition ◽  
Particulate Mercury

Abstract. A comprehensive measurement study of mercury wet deposition and size-fractionated particulate mercury (HgP) concurrent with meteorological variables was conducted from June 2011 to February 2012 to evaluate the characteristics of mercury deposition and particulate mercury in urban Nanjing, China. The volume-weighted mean (VWM) concentration of mercury in rainwater was 52.9 ng L−1 with a range of 46.3–63.6 ng L−1. The wet deposition per unit area was averaged 56.5 μg m−2 over 9 months, which was lower than that in most Chinese cities, but much higher than annual deposition in urban North America and Japan. The wet deposition flux exhibited obvious seasonal variation strongly linked with the amount of precipitation. Wet deposition in summer contributed more than 80% to the total amount. A part of contribution to wet deposition of mercury from anthropogenic sources was evidenced by the association between wet deposition and sulfates, as well as nitrates in rainwater. The ions correlated most significantly with mercury were formate, calcium, and potassium, which suggested that natural sources including vegetation and resuspended soil should be considered as an important factor to affect the wet deposition of mercury in Nanjing. The average HgP concentration was 1.10 ± 0.57 ng m−3. A distinct seasonal distribution of HgP concentrations was found to be higher in winter as a result of an increase in the PM10 concentration. Overall, more than half of the HgP existed in the particle size range less than 2.1 μm. The highest concentration of HgP in coarse particles was observed in summer, while HgP in fine particles dominated in fall and winter. The size distribution of averaged mercury content in particulates was bimodal, with two peaks in the bins of < 0.7 μm and 4.7–5.8 μm. Dry deposition per unit area of HgP was estimated to be 47.2 μg m−2 using meteorological conditions and a size-resolved particle dry deposition model. This was 16.5% less than mercury wet deposition. Compared to HgP in fine particles, HgP in coarse particles contributed more to the total dry deposition due to higher deposition velocities. Negative correlation between precipitation and the HgP concentration reflected the effect of scavenging of HgP by precipitation.

scholarly journals Temporal and Spatial variation of Contribution from Ship Emissions to the concentration and deposition of air pollutants in the Baltic Sea

2016 ◽  
Author(s):  
Karin Haglund ◽  
Björn Claremar ◽  
Anna Rutgersson
Keyword(s):  
Atmospheric Deposition ◽  
Baltic Sea ◽  
Dry Deposition ◽  
Air Pollutants ◽  
Wet Deposition ◽  
Sulphur Content ◽  
The Baltic Sea ◽  
Near Surface ◽  
Baltic Sea Region ◽  
The Baltic

Abstract. The shipping sector contributes significantly to increasing emissions of air pollutants. In order to achieve sustainable shipping, primarily through new regulations and techniques, greater knowledge of dispersion and deposition of air pollutants is required. Regional model calculations of the dispersion and deposition of sulphur, nitrogen and particulate matter from the international maritime sector in the Baltic Sea and the North Sea have been made for the years 2009 to 2013. In some areas in the Baltic Sea region the contribution of sulphur dioxide, nitrogen oxide and nitrogen dioxide from international shipping represented up to 80 % of the total near surface concentration of the pollutants. Contributions from shipping of PM2,5 and PM10 were calculated to a maximum of 21 % and 13 % respectively. The contribution of wet deposition of sulphur from shipping was maximum 29 % of the total wet deposition, and for dry deposition the contribution from shipping was maximum 84 %. The highest percentage contribution of wet deposition of nitrogen from shipping reached 28 % and for dry deposition 47 %. The highest concentrations and deposition of the pollutants in the study were found near large ports and shipping lanes. High concentrations were also found over larger areas at sea and over land where many people are exposed. With enhanced regulations for sulphur content in maritime fuel, the cleaning of exhausts through scrubbers has become a possible economic solution. Wet scrubbers meet the air quality criteria but their consequences for the marine environment are largely unknown. The resulting potential of future acidification in the Baltic Sea, both from atmospheric deposition and from open-loop scrubber water along the shipping lanes, based on different assumptions about sulphur content in fuel and scrubber usage has been assessed. Shipping is expected to increase globally and in the Baltic Sea region, deposition of sulphur due to shipping will depend on traffic density, emission regulations and technology choices for the emission controls. To evaluate future changes scenarios are developed considering the amount of scrubber technology used. The increase in deposition for the different scenarios differs slightly for the basins in the Baltic Sea. The proportion of ocean acidifying sulphur from ships increases when taking scrubber water into account and the major reason to increasing acidifying nitrogen from ships are due to increasing ship traffic. This study also generates a database of scenarios for atmospheric deposition and scrubber exhaust from the period 2011 to 2050.

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