scholarly journals Chlorine oxidation of VOCs at a semi-rural site in Beijing: Significant chlorine liberation from ClNO<sub>2</sub> and subsequent gas and particle phase Cl-VOC production

2018 ◽  
Author(s):  
Michael Le Breton ◽  
Åsa M. Hallquist ◽  
Ravi Kant Pathak ◽  
David Simpson ◽  
Yujue Wang ◽  
...  
Keyword(s):  
Chlorine Atom ◽  
Ambient Air ◽  
Anthropogenic Sources ◽  
Rural Site ◽  
Anthropogenic Source ◽  
High Time Resolution ◽  
Particle Phase ◽  
Night Time ◽  
Relative Contribution ◽  
High Concentrations

Abstract. Nitryl Chloride (ClNO2) accumulation at night-time acts as a significant reservoir for active chlorine and impacts the following day's photochemistry when the chlorine atom is liberated at sunrise. Here, we report simultaneous measurements of N2O5, a suite of inorganic halogens including ClNO2 and Cl-VOCs in the gas and particle phase utilizing the FIGAERO-ToF-CIMS during an intensive measurement campaign 40 km Northwest of Beijing in May and June 2016. A maximum concentration of 2900 ppt of ClNO2 was observed with a mean campaign night-time concentration of 487 ppt, appearing to have an anthropogenic source supported by correlation with SO2, CO and benzene, which often persisted at high levels after sunrise until midday. This was attributed to such high concentrations persisting after numerous e-folding times of the photolytic lifetime enabling the chlorine atom production to reach 2.3 × 105 molecules cm−3 from ClNO2 alone, peaking at 9:30 am and up to 8.4 × 105 molecules cm−3 when including the supporting inorganic halogen measurements. Cl-VOCs were measured in the particle and gas phase for the first time at high time resolution and illustrate how the iodide ToF-CIMS can detect unique markers of chlorine atom chemistry in ambient air from both biogenic and anthropogenic sources. Their presence and abundance can be explained via time series of their measured and steady state calculated precursors, enabling the assessment of competing OH and chlorine atom oxidation via measurements of products from both of these mechanisms and their relative contribution to SOA formation.

scholarly journals Chlorine oxidation of VOCs at a semi-rural site in Beijing: significant chlorine liberation from ClNO<sub>2</sub> and subsequent gas- and particle-phase Cl–VOC production

2018 ◽  
Vol 18 (17) ◽  
pp. 13013-13030 ◽  
Author(s):  
Michael Le Breton ◽  
Åsa M. Hallquist ◽  
Ravi Kant Pathak ◽  
David Simpson ◽  
Yujue Wang ◽  
...  
Keyword(s):  
Chlorine Atom ◽  
Ambient Air ◽  
Anthropogenic Sources ◽  
Rural Site ◽  
Anthropogenic Source ◽  
High Time Resolution ◽  
Mixing Ratio ◽  
Mixing Ratios ◽  
Relative Contribution ◽  
Unique Markers

Abstract. Nitryl chloride (ClNO2) accumulation at night acts as a significant reservoir for active chlorine and impacts the following day's photochemistry when the chlorine atom is liberated at sunrise. Here, we report simultaneous measurements of N2O5 and a suite of inorganic halogens including ClNO2 and reactions of chloride with volatile organic compounds (Cl–VOCs) in the gas and particle phases utilising the Filter Inlet for Gas and AEROsols time-of-flight chemical ionisation mass spectrometer (FIGAERO-ToF-CIMS) during an intensive measurement campaign 40 km northwest of Beijing in May and June 2016. A maximum mixing ratio of 2900 ppt of ClNO2 was observed with a mean campaign nighttime mixing ratio of 487 ppt, appearing to have an anthropogenic source supported by correlation with SO2, CO and benzene, which often persisted at high levels after sunrise until midday. This was attributed to such high mixing ratios persisting after numerous e-folding times of the photolytic lifetime enabling the chlorine atom production to reach 2.3  ×  105 molecules cm−3 from ClNO2 alone, peaking at 09:30 LT and up to 8.4  ×  105 molecules cm−3 when including the supporting inorganic halogen measurements.Cl–VOCs were observed in the particle and gas phases for the first time at high time resolution and illustrate how the iodide ToF-CIMS can detect unique markers of chlorine atom chemistry in ambient air from both biogenic and anthropogenic sources. Their presence and abundance can be explained via time series of their measured and steady-state calculated precursors, enabling the assessment of competing OH and chlorine atom oxidation via measurements of products from both of these mechanisms and their relative contribution to secondary organic aerosol (SOA) formation.

scholarly journals Hydrochemical assessment and groundwater pollution parameters in arid zone: Case of the Turonian aquifer in Béchar region, southwestern Algeria

2018 ◽  
Vol 39 (1) ◽  
pp. 109-117
Author(s):  
Ikram Mokeddem ◽  
Meriem Belhachemi ◽  
Touhami Merzougui ◽  
Noria Nabbou ◽  
Salih Lachache
Keyword(s):  
Irrigation Water ◽  
Major Ions ◽  
Arid Zone ◽  
Water Source ◽  
Anthropogenic Sources ◽  
Anthropogenic Source ◽  
Water Sampling ◽  
Drinking And Irrigation ◽  
Groundwater Samples ◽  
High Concentrations

AbstractGroundwater samples from Turonian aquifer of Béchar region were evaluated as drinking and irrigation water sources. physicochemical parameters including pH, EC, TH, Na+, Ca2+, Mg2+, Cl−, SO42– and NO3− were determined for 16 water sampling points. These characterizations show that the groundwater is fresh to brackish, slightly alkaline and the major ions are Na+, Ca2+, Mg2+, Cl− and SO42–. According to WHO standards, 50% of the analysed water are suitable as a drinking source while the other samples are not in compliance with drinking water standards. This non-compliance is basically due to the high concentrations of Na+, Cl−, and SO42– requesting further treatment to reach the stringent standards. According to the results of nitrate concentrations, anthropogenic source seems to influence the groundwater quality. The present study shows that Béchar groundwater may represent an important drinking and irrigation water source. However, a specific management strategy should be adapted in order to avoid the contamination by anthropogenic sources.

scholarly journals Measurements of higher alkanes using NO<sup>+</sup>PTR-ToF-MS: significant contributions of higher alkanes to secondary organic aerosols in China

2020 ◽  
Author(s):  
Chaomin Wang ◽  
Caihong Wu ◽  
Sihang Wang ◽  
Jipeng Qi ◽  
Baolin Wang ◽  
...  
Keyword(s):  
North China Plain ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Rural Site ◽  
Urban Site ◽  
Accurate Estimation ◽  
High Time Resolution ◽  
Single Ring ◽  
High Concentrations ◽  
Tof Ms

Abstract. Higher alkanes are a major class of intermediate-volatility organic compounds (IVOCs), which have been proposed to be important precursors of secondary organic aerosols (SOA) in the atmosphere. Accurate estimation of SOA from higher alkanes and their oxidation processes in the atmosphere are limited, partially due to difficulty in their measurements. High-time resolution (10 s) measurements of higher alkanes were performed using a novel online mass spectrometry method at an urban site of Guangzhou in Pearl River Delta (PRD) and at a rural site in North China Plain (NCP), respectively. High concentrations were observed in both environments, with significant diurnal variations. At both sites, SOA production from higher alkanes is estimated from their photochemical losses and SOA yields. Higher alkanes account for significant fractions of SOA formation at the two sites, with average contributions of 7.0 ± 8.0 % in Guangzhou and 7.1 ± 9.5 % in NCP, which are comparable or even higher than both single-ring aromatics and naphthalenes. The significant contributions of higher alkanes in SOA formation suggests that they should be explicitly included in current models for SOA formation. Our work also highlights the importance of NO+PTR-ToF-MS in measuring higher alkanes and quantifying their contributions to SOA formation.

scholarly journals Winter Ozone Pollution in Utah’s Uinta Basin is Attenuating

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 4
Author(s):  
Marc L. Mansfield ◽  
Seth N. Lyman
Keyword(s):  
Ground Level ◽  
Ambient Air ◽  
Quality Standard ◽  
Ozone Pollution ◽  
Uinta Basin ◽  
Concentration Data ◽  
Previous Decade ◽  
High Concentrations ◽  
Ambient Air Quality Standard ◽  
Ozone Precursor

High concentrations of ground-level ozone have been observed during wintertime in the Uinta Basin of western Utah, USA, beginning in 2010. We analyze existing ozone and ozone precursor concentration data from 38 sites over 11 winter seasons and conclude that there has been a statistically significant (p < 0.02) decline in ozone concentration over the previous decade. Daily exceedances of the National Ambient Air Quality Standard for ozone (70 ppb) have been trending downward at the rate of nearly four per year. Ozone and NOx concentrations have been trending downward at the rates of about 3 and 0.3 ppb per year, respectively. Concentrations of organics in 2018 were at about 30% of their values in 2012 or 2013. Several markers, annual ozone exceedance counts and median ozone and NOx concentrations, were at their largest values in the period 2010 to 2013 and have never recovered since then. We attribute the decline to (1) weakening global demand for oil and natural gas and (2) more stringent pollution regulations and controls, both of which have occurred over the previous decade. We also see evidence of ozone titration when snow cover is absent.

scholarly journals Six-year source apportionment of submicron organic aerosols from near-continuous measurements at SIRTA (Paris area, France)

2019 ◽  
Author(s):  
Yunjiang Zhang ◽  
Olivier Favez ◽  
Jean-Eudes Petit ◽  
Francesco Canonaco ◽  
Francois Truong ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Ambient Air ◽  
Carbonaceous Aerosols ◽  
Time Resolved ◽  
Pronounced Increase ◽  
Paris Area ◽  
Multi Wavelength ◽  
High Concentrations

Abstract. Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly-time resolved year-round characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of Aerosol Chemical Speciation Monitor (ACSM) and multi-wavelength aethalometer from November 2011 to March 2018 at a background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase of LO-OOA concentrations and contributions (50–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely high concentrations and OA contributions (32–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter, and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about 200 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil fuel and biomass burning black carbon components), and no trend for LO-OOA over the 6+-year investigated period.

scholarly journals Air Pollution, housing and respirfatory tract Infections in Children: NatIonal birth Cohort study (PICNIC): study protocol

BMJ Open ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. e048038
Author(s):  
Graziella Favarato ◽  
Tom Clemens ◽  
Steven Cunningham ◽  
Chris Dibben ◽  
Alison Macfarlane ◽  
...  
Keyword(s):  
Air Pollution ◽  
Cohort Study ◽  
Respiratory Tract Infections ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Birth Cohort Study ◽  
Housing Conditions ◽  
Relative Contribution ◽  
Housing Characteristics ◽  
Tract Infections

IntroductionRespiratory tract infections (RTIs) are the most common reason for hospital admission among children <5 years in the UK. The relative contribution of ambient air pollution exposure and adverse housing conditions to RTI admissions in young children is unclear and has not been assessed in a UK context.Methods and analysisThe aim of the PICNIC study (Air Pollution, housing and respiratory tract Infections in Children: NatIonal birth Cohort Study) is to quantify the extent to which in-utero, infant and childhood exposures to ambient air pollution and adverse housing conditions are associated with risk of RTI admissions in children <5 years old. We will use national administrative data birth cohorts, including data from all children born in England in 2005–2014 and in Scotland in 1997–2020, created via linkage between civil registration, maternity and hospital admission data sets. We will further enhance these cohorts via linkage to census data on housing conditions and socioeconomic position and small area-level data on ambient air pollution and building characteristics. We will use time-to-event analyses to examine the association between air pollution, housing characteristics and the risk of RTI admissions in children, calculate population attributable fractions for ambient air pollution and housing characteristics, and use causal mediation analyses to explore the mechanisms through which housing and air pollution influence the risk of infant RTI admission.Ethics, expected impact and disseminationTo date, we have obtained approval from six ethics and information governance committees in England and two in Scotland. Our results will inform parents, national and local governments, the National Health Service and voluntary sector organisations of the relative contribution of adverse housing conditions and air pollution to RTI admissions in young children. We will publish our results in open-access journals and present our results to the public via parent groups and social media and on the PICNIC website. Code and metadata will be published on GitHub.

Geochemistry of cobalt, nickel, chromium, and vanadium in the sediments of the estuary and open Gulf of St. Lawrence

1979 ◽  
Vol 16 (6) ◽  
pp. 1196-1209 ◽  
Author(s):  
D. H. Loring
Keyword(s):  
Mineral Deposit ◽  
Source Rocks ◽  
Anthropogenic Sources ◽  
Terrestrial Organic Matter ◽  
Lawrence Estuary ◽  
Fine Grained ◽  
Hydrous Oxides ◽  
High Concentrations ◽  
St Lawrence Estuary ◽  
Local Anomalies

Total Co (3–22 ppm), Ni (4–160 ppm), V (4–168 ppm), and Cr (8–241 ppm) concentrations vary regionally and with textural differences in the sediments of the St. Lawrence estuary and Gulf of St. Lawrence. They are, except for local anomalies, at or near natural levels relative to their source rocks and other marine sediments.Chemical partition and mineralogical analyses indicate that small but biochemically significant quantities (2–24%) of the total element concentrations are potentially available to the biota and are most likely held by fine-grained organic material, hydrous iron oxides, and ion exchange positions in the sediments. In the upper estuary, nondetrital Ni, Cr, and V supplied from natural and anthropogenic (Cr) sources are apparently preferentially scavenged from solution by terrestrial organic matter and hydrous oxides and concentrated in fine-grained sediments deposited below the turbidity maximum. In the lower estuary, the fine-grained sediments are relatively enriched in nondetrital V supplied from anthropogenic sources in the Saguenay system. Elsewhere the sedimentation intensities of the nondetrital elemental contributions have remained relatively constant with fluctuations in total sediment intensity.Seventy-six to 98% of the total Co, Ni, Cr, and V is not, however, available to the biota, but held in various sulphide, oxide, and silicate minerals. The host minerals have accumulated at the same rate as other fine-grained detrital material except for some local anomalies. In the upper estuary, detrital V concentrations are highest in the sands as an apparent result of an enrichment of ilmenite and titaniferous magnetite from a nearby mineral deposit. In the open gulf, relatively high concentrations of Ni, Cr, and V occur in sediments from the Bay of Islands, Newfoundland, and probably result from the seaward dispersal of detrital Ni, Cr, and V bearing minerals from nearby ultrabasic rocks.

Night-time chemistry of biomass burning plumes in urban areas: A dual mobile chamber study

2021 ◽  
Author(s):  
Spiro Jorga ◽  
Kalliopi Florou ◽  
Christos Kaltsonoudis ◽  
John Kodros ◽  
Christina Vasilakopoulou ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Urban Areas ◽  
Mass Spectra ◽  
Prescribed Burning ◽  
Organic Aerosol ◽  
Photochemical Activity ◽  
Organic Nitrate ◽  
Night Time ◽  
Starting Point ◽  
High Concentrations

&lt;p&gt;Biomass burning including residential heating, agricultural fires, prescribed burning, and wildfires is a major source of gaseous and particulate pollutants in the atmosphere. Although, important changes in the size distributions and the chemical composition of the biomass burning aerosol during daytime chemistry have been observed, the corresponding changes at nighttime or in winter where photochemistry is slow, have received relatively little attention. In this study, we tested the hypothesis that nightime chemistry in biomass burning plumes can be rapid in urban areas using a dual smog chamber system.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Ambient urban air during winter nighttime periods with high concentrations of ambient biomass burning organic aerosol is used as the starting point. Ozone was added in the perturbed chamber to simulate mixing with background air (and subsequent NO&lt;sub&gt;3&lt;/sub&gt; production and aging) while the second chamber was used as a reference. Following the injection of ozone rapid organic aerosol (OA) formation was observed in all experiments leading to increases of the OA concentration by 20-70%. The oxygen to carbon ratio of the OA increased by 50% on average and the mass spectra of the produced OA was quite similar to that of the oxidized OA mass spectra reported during winter in urban areas. Good correlation was also observed with the produced mass spectra from nocturnal aging of laboratory biomass burning emissions showing the strong contribution of biomass burning emissions in the SOA formation during cold nights with high biomass burning activities. Concentrations of NO&lt;sub&gt;3&lt;/sub&gt; radicals as high as 25 ppt were measured in the perturbed chamber with an accompanying production of 0.2-1.2 &amp;#956;g m&lt;sup&gt;-3&lt;/sup&gt; of organic nitrate. These results strongly indicate that the OA in biomass burning plumes can evolve rapidly even during wintertime periods with low photochemical activity.&lt;/p&gt;

Hydrochemistry and carbonate sediment characterisation of Bacalar Lagoon, Mexican Caribbean

2019 ◽  
Vol 70 (3) ◽  
pp. 382 ◽  
Author(s):  
Nidia I. Tobón Velázquez ◽  
Mario Rebolledo Vieyra ◽  
Adina Paytan ◽  
Kyle H. Broach ◽  
Laura M. Hernández Terrones
Keyword(s):  
Trace Elements ◽  
Water Column ◽  
Saturation Index ◽  
Major Elements ◽  
Anthropogenic Sources ◽  
Pollution Indices ◽  
Mexican Caribbean ◽  
High Concentrations ◽  
Geochemical Analyses ◽  
Changes Over Time

The aim of the study is to determine the distribution of trace and major elements in the water and in the sediments of the south part of the Bacalar Lagoon and to identify the sources of the trace elements and their changes over time. The western part of the lagoon water column is characterised by high concentrations of Ca2+, HCO3– and Sr2+, derived from groundwater input. In contrast, the eastern part of the lagoon is characterised by high concentrations of Mg2+, Na+ and Cl–. The lagoon is not affected by present-day seawater intrusion. Water column and sediment geochemical analyses performed in Bacalar Lagoon show clear spatial distribution of different parameters. The saturation index of the water column indicates three main groups: (1) a zone oversaturated with regard to aragonite, calcite and dolomite; (2) an undersaturated area where all three minerals are dissolving; and (3) an area with calcite equilibrium and undersaturation with regard to the other minerals. Herein we present the first measurements of trace element (Ba2+, Mn2+, K+, Ni2+, Zn2+) concentrations in carbonates obtained from sediments in Bacalar Lagoon. In order to evaluate whether the trace elements are derived from natural or anthropogenic sources, four pollution indices were calculated. The results confirmed that Bacalar Lagoon sediments are not contaminated with Ni2+, K+, Mn2+ and Ba2+, and that the Zn2+ seems to have a predominantly anthropogenic origin.

scholarly journals Polyfluoroalkyl compounds in the Canadian Arctic atmosphere

2011 ◽  
Vol 8 (4) ◽  
pp. 399 ◽  
Author(s):  
Lutz Ahrens ◽  
Mahiba Shoeib ◽  
Sabino Del Vento ◽  
Garry Codling ◽  
Crispin Halsall
Keyword(s):  
Gas Phase ◽  
Environmental Concern ◽  
Canadian Arctic ◽  
High Volume ◽  
Ambient Air ◽  
Coast Guard ◽  
The Arctic ◽  
Particle Phase ◽  
Method Performance ◽  
Arctic Atmosphere

Environmental contextPerfluoroalkyl compounds are of rising environmental concern because of their ubiquitous distribution in remote regions like the Arctic. The present study quantifies these contaminants in the gas and particle phases of the Canadian Arctic atmosphere. The results demonstrate the important role played by gas–particle partitioning in the transport and fate of perfluoroalkyl compounds in the atmosphere. AbstractPolyfluoroalkyl compounds (PFCs) were determined in high-volume air samples during a ship cruise onboard the Canadian Coast Guard Ship Amundsen crossing the Labrador Sea, Hudson Bay and the Beaufort Sea of the Canadian Arctic. Five PFC classes (i.e. perfluoroalkyl carboxylates (PFCAs), polyfluoroalkyl sulfonates (PFSAs), fluorotelomer alcohols (FTOHs), fluorinated sulfonamides (FOSAs), and sulfonamidoethanols (FOSEs)) were analysed separately in the gas phase collected on PUF/XAD-2 sandwiches and in the particle phase on glass-fibre filters (GFFs). The method performance of sampling, extraction and instrumental analysis were compared between two research groups. The FTOHs were the dominant PFCs in the gas phase (20–138 pg m–3), followed by the FOSEs (0.4–23 pg m–3) and FOSAs (0.5–4.7 pg m–3). The PFCAs could only be quantified in the particle phase with low levels (<0.04–0.18 pg m–3). In the particle phase, the dominant PFC class was the FOSEs (0.3–8.6 pg m–3). The particle-associated fraction followed the general trend of: FOSEs (~25 %) > FOSAs (~9 %) > FTOHs (~1 %). Significant positive correlation between ∑FOSA concentrations in the gas phase and ambient air temperature indicate that cold Arctic surfaces, such as the sea-ice snowpack and surface seawater could be influencing FOSAs in the atmosphere.

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