A STUDY OF WET DEPOSITION FLUX USING THE SEQUENTIAL SAMPLING TECHNIQUE

2011 ◽  
Author(s):  
O. Akkoyunlu
Keyword(s):  
Wet Deposition ◽  
Sequential Sampling ◽  
Sampling Technique ◽  
Deposition Flux ◽  
Wet Deposition Flux

scholarly journals Impacts of Anthropogenic Emissions and Meteorological Variation on Hg Wet Deposition in Chongming, China

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1301
Author(s):  
Yi Tang ◽  
Qingru Wu ◽  
Wei Gao ◽  
Shuxiao Wang ◽  
Zhijian Li ◽  
...  
Keyword(s):  
Wet Deposition ◽  
Warm Season ◽  
Meteorological Condition ◽  
Anthropogenic Emissions ◽  
Deposition Flux ◽  
Wet Deposition Flux ◽  
Meteorological Variation ◽  
Global Concern ◽  
The Impact

Mercury (Hg) is a ubiquitous environmental toxicant that has caused global concern due to its persistence and bioaccumulation in the environment. Wet deposition is a crucial Hg input for both terrestrial and aquatic environments and is a significant indicator for evaluating the effectiveness of anthropogenic Hg control. Rainwater samples were collected from May 2014 to October 2018 in Chongming Island to understand the multi-year Hg wet deposition characteristics. The annual Hg wet deposition flux ranged from 2.6 to 9.8 μg m−2 yr−1 (mean: 4.9 μg m−2 yr−1). Hg wet deposition flux in Chongming was comparable to the observations at temperate and subtropical background sites (2.0–10.2 μg m−2 yr−1) in the northern hemisphere. Hg wet deposition flux decreased from 8.6 μg m−2 yr−1 in 2014–2015 to 3.8 μg m−2 yr−1 in 2016 and was attributed to a decrease in the volume-weighted mean (VWM) Hg concentration (−4.1 ng L−1 yr−1). The reduced VWM Hg was explained by the decreasing atmospheric Hg and anthropogenic emissions reductions. The annual Hg wet deposition flux further decreased from 3.8 μg m−2 in 2016 to 2.6 μg m−2 in 2018. The reduction of warm season (April–September) rainfall amounts (356–845 mm) mainly contributed to the Hg wet deposition flux reduction during 2016–2018. The multi-year monitoring results suggest that long-term measurements are necessary when using wet deposition as an indicator to reflect the impact of anthropogenic efforts on mercury pollution control and meteorological condition variations.

scholarly journals Subtropical subsidence and surface deposition of oxidized mercury produced in the free troposphere

2017 ◽  
Vol 17 (14) ◽  
pp. 8999-9017 ◽  
Author(s):  
Viral Shah ◽  
Lyatt Jaeglé
Keyword(s):  
Boundary Layer ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Transport Model ◽  
Lower Troposphere ◽  
Deposition Flux ◽  
Surface Deposition ◽  
Middle Troposphere ◽  
Western Us ◽  
Wet Deposition Flux

Abstract. Oxidized mercury (Hg(II)) is chemically produced in the atmosphere by oxidation of elemental mercury and is directly emitted by anthropogenic activities. We use the GEOS-Chem global chemical transport model with gaseous oxidation driven by Br atoms to quantify how surface deposition of Hg(II) is influenced by Hg(II) production at different atmospheric heights. We tag Hg(II) chemically produced in the lower (surface–750 hPa), middle (750–400 hPa), and upper troposphere (400 hPa–tropopause), in the stratosphere, as well as directly emitted Hg(II). We evaluate our 2-year simulation (2013–2014) against observations of Hg(II) wet deposition as well as surface and free-tropospheric observations of Hg(II), finding reasonable agreement. We find that Hg(II) produced in the upper and middle troposphere constitutes 91 % of the tropospheric mass of Hg(II) and 91 % of the annual Hg(II) wet deposition flux. This large global influence from the upper and middle troposphere is the result of strong chemical production coupled with a long lifetime of Hg(II) in these regions. Annually, 77–84 % of surface-level Hg(II) over the western US, South America, South Africa, and Australia is produced in the upper and middle troposphere, whereas 26–66 % of surface Hg(II) over the eastern US, Europe, and East Asia, and South Asia is directly emitted. The influence of directly emitted Hg(II) near emission sources is likely higher but cannot be quantified by our coarse-resolution global model (2° latitude  ×  2.5° longitude). Over the oceans, 72 % of surface Hg(II) is produced in the lower troposphere because of higher Br concentrations in the marine boundary layer. The global contribution of the upper and middle troposphere to the Hg(II) dry deposition flux is 52 %. It is lower compared to the contribution to wet deposition because dry deposition of Hg(II) produced aloft requires its entrainment into the boundary layer, while rain can scavenge Hg(II) from higher altitudes more readily. We find that 55 % of the spatial variation of Hg wet deposition flux observed at the Mercury Deposition Network sites is explained by the combined variation of precipitation and Hg(II) produced in the upper and middle troposphere. Our simulation points to a large role of the dry subtropical subsidence regions. Hg(II) present in these regions accounts for 74 % of Hg(II) at 500 hPa over the continental US and more than 60 % of the surface Hg(II) over high-altitude areas of the western US. Globally, it accounts for 78 % of the tropospheric Hg(II) mass and 61 % of the total Hg(II) deposition. During the Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) aircraft campaign, the contribution of Hg(II) from the dry subtropical regions was found to be 75 % when measured Hg(II) exceeded 250 pg m−3. Hg(II) produced in the upper and middle troposphere subsides in the anticyclones, where the dry conditions inhibit the loss of Hg(II). Our results highlight the importance the subtropical anticyclones as the primary conduits for the production and export of Hg(II) to the global atmosphere.

scholarly journals Temporal and Spatial Variations of Wet Deposition Flux of Mineral Dust in Japan

SOLA ◽  
2011 ◽  
Vol 7 ◽  
pp. 49-52 ◽  
Author(s):  
K. Osada ◽  
S. Ura ◽  
M. Kagawa ◽  
M. Mikami ◽  
T. Y. Tanaka ◽  
...  
Keyword(s):  
Wet Deposition ◽  
Mineral Dust ◽  
Spatial Variations ◽  
Deposition Flux ◽  
Temporal And Spatial Variations ◽  
Wet Deposition Flux ◽  
Temporal And Spatial

scholarly journals Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

2017 ◽  
Vol 17 (4) ◽  
pp. 2689-2708 ◽  
Author(s):  
Francesca Sprovieri ◽  
Nicola Pirrone ◽  
Mariantonia Bencardino ◽  
Francesco D'Amore ◽  
Helene Angot ◽  
...  
Keyword(s):  
Wet Deposition ◽  
Observation System ◽  
Deposition Flux ◽  
Data Set ◽  
New Findings ◽  
Tropical Areas ◽  
Wet Deposition Flux ◽  
Wet Scavenging ◽  
Northern And Southern Hemispheres ◽  
Precipitation Events

Abstract. The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.

scholarly journals Environmental effect of heavy metals deposition in arid city

2019 ◽  
Keyword(s):  
Heavy Metals ◽  
Dry Deposition ◽  
Arid Region ◽  
Wet Deposition ◽  
Environmental Effect ◽  
Deposition Flux ◽  
Rain Event ◽  
Heating Period ◽  
Deposition Fluxes ◽  
Wet Deposition Flux

<p>This paper analysis the contents and variation of heavy metals in wet and dry deposition in Changji (Xinjiang, China) revealed their reducing regularity for heavy metals in atmosphere in arid area. Samples (including 84 dry deposition samples and 16 wet deposition samples) were collected from January 2016 to December 2016, and the contents of heavy metals (Ni, Cu, Cd and Pb) were analyzed by AA-7000 atomic absorption spectrophotometer. The dry deposition fluxes of Ni, Cu, Cd and Pb are 3.70 mg/( m2.a), 4.81 mg/( m2. a), 0.53 mg/( m2•a) and 22.74 mg/( m2•a), respectively; the wet deposition fluxes of Ni, Cu, Cd and Pb are 0.77mg/( m2•a), 3.25mg/( m2•a), 0.04mg/( m2•a) and 0.11mg/( m2•a), respectively. Each of the four heavy metals deposition fluxes during heating period was higher than non-heating period, especially for Pb and Cd, which is mainly due to the emission of coal combustion for heating. During sampling periods, the ratio of wet deposition flux to total for Ni, Cu, Cd and Pb are 17.21%, 40.33%, 7.67% and 0.48%, respectively; the wet deposition flux is far less than dry deposition, especially for Pb. The rate of dry deposition is lower than wet deposition, however dry deposition plays an important role in scavenging heavy metals in arid region. Arid region has a low intensity and frequency of rain event, heavy metals were mainly scavenging by dry deposition attribute to its continuous and dependable process. Dry deposition has much more environmental effect on heavy metal in arid region.</p>

Wet Deposition Fluxes of Nitrate and Ammonium at a Rural Agricultural Site in north India

2021 ◽  
Author(s):  
Sudesh Yadav ◽  
Umesh Kulshrestha
Keyword(s):  
Wet Deposition ◽  
Major Ions ◽  
Monsoon Season ◽  
North India ◽  
Reactive Nitrogen ◽  
Deposition Flux ◽  
Deposition Fluxes ◽  
Average Value ◽  
Wet Deposition Flux ◽  
Agricultural Site

&lt;p&gt;The chemical composition of rainwater is an indicator of the air quality and sources of influence. In this study, pH and ionic concentrations were measured in rain samples collected during monsoon season of 2018 at a rural agricultural site located in northern part of India. Wet deposition fluxes of reactive nitrogen species NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; over NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; were calculated to estimate their annual deposition. The pH of samples varied between 5.2 and 6.14, with an average value of 5.72 which is in alkaline range considering 5.6 as the neutral pH of cloud water with atmospheric CO&lt;sub&gt;2&lt;/sub&gt; equilibrium. These relatively high pH values indicate the neutralisation of acidity in precipitation. Samples were analysed for their cationic and anionic content using ion chromatography. The results showed that NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; concentrations were higher than NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;- &lt;/sup&gt;with the VWM concentrations of 187.23 &amp;#956;eql&lt;sup&gt;-1&lt;/sup&gt; and 26.79 &amp;#956;eql&lt;sup&gt;-1&lt;/sup&gt; respectively. Furthermore, wet deposition flux of NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;-N was calculated as 4.25 kg ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; while that of NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;-N was as 2.10 kg ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;. VWM concentrations of major ions decreased in the following order NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; &gt; Ca&lt;sup&gt;2+&lt;/sup&gt; &gt; SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; &gt; NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; &gt; K&lt;sup&gt;+&lt;/sup&gt; &gt; Cl&lt;sup&gt;-&lt;/sup&gt; &gt; Na&lt;sup&gt;+&lt;/sup&gt; &gt; Mg&lt;sup&gt;2+&lt;/sup&gt;. In this study, relatively high NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; concentrations in rainwater can be attributed to nearby agricultural activities, excreta and biomass burning.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords:&lt;/strong&gt; Rainwater, Neutralisation, VWM concentration, Agricultural site, Reactive Nitrogen.&lt;/p&gt;

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