The importance of non-fossil sources in carbonaceous aerosols in a megacity of central China during the 2013 winter haze episode: A source apportionment constrained by radiocarbon and organic tracers

TL;DR: In this paper, a source apportionment of different carbonaceous aerosols (CAs) was conducted in a megacity in central China (Wuhan, Hubei Province) by using the measurements of radiocarbon and molecular organic tracers.

About: This article is published in Atmospheric Environment.The article was published on 2016-11-01 and is currently open access. It has received 26 citations till now. The article focuses on the topics: Haze & Total organic carbon.

Summary

Introduction

• Testing for anaemia in pregnancy is ubiquitous across low and high income countries and usually begins at the booking (first antenatal) appointment.
• Screening may range from looking for risk factors and clinical features of anaemia in the history, to point of care testing or laboratory assessment of the full blood count with or without assessment of iron parameters from a venous sample.
• (1) Which of these provides the most reliable and cost effective assessment remains unanswered.
• The authors will provide an overview of the landscape of the literature surrounding the use of haemoglobin as a screening tool for anaemia in pregnancy, the implications this has on clinical care, resource allocation and national and international policy.

Why is anaemia screening important?

• It is widely acknowledged that anaemia in pregnancy is associated with significant morbidity and mortality (if severe) for the mother, independently of other factors.
• (3) Anaemia has also been associated with adverse outcomes for the developing baby, including low birth weight and preterm delivery.
• This reduces the need for additional screening tests and avoids delays in management.
• (8) This may make a case for routine iron supplementation.
• (7) The ongoing high prevalence of anaemia globally and the lack of evidence demonstrating safety and efficacy of routine iron supplementation in pregnancy highlights unmet clinical and research needs.

Low and middle income countries

• More than 1.6 billion people are anaemic, with 42% of all pregnant women worldwide affected.
• In these settings the causes of anaemia are often complex, however the global focus currently remains on iron deficiency anaemia.
• (1) Those found to be anaemic should be offered daily iron supplementation and those not yet anaemic offered iron and folic acid weekly.
• Below the authors discuss a few key issues briefly.
• (16) While each micronutrients have specific roles, multiple deficiencies tend to cluster within individuals, acting synergistically increasing the burden of disease.

Soil-transmitted helminths

• Infectious diseases such as hookworm reduce absorption and metabolism of key micronutrients (notably iron) in addition to increasing gastrointestinal tract losses.
• Hookworm infections contribute greatly to the high prevalence of anaemia in sub-Saharan Africa and Southeast Asia, with an estimated 576–740 million infections.
• There are clear benefits from pooled estimates of randomized controlled trials of deworming and concomitant iron supplementation strategies showing improvements in mean haemoglobin concentration across sub-Saharan Africa. (18).
• As a result, the current WHO recommendation for preventive chemotherapy include using single-dose albendazole (400 mg) or mebendazole (500 mg), as a public health intervention for pregnant women, after the first trimester, living in areas where both anaemia and soil transmitted helminth infections are considered endemic. (19).

Malaria

• Malarial infection, particularly plasmodium falciparum can lead to and worsen preexisting anaemia.
• (20) The balance of iron supplementation in the context of malarial infection (suspected or confirmed) requires careful consideration; it has been an area of considerable debate.
• (20, 21) In areas such as Africa, WHO recommends prevention and treatment of malaria during pregnancy using of long-lasting insecticidal nets ; in all areas with moderate to high malaria transmission in Africa, intermittent preventive treatment in pregnancy (IPTP) with sulfadoxine-pyrimethamine (SP), as part of antenatal care services and prompt diagnosis and effective treatment of malaria infections.

HIV related causes

• HIV infection and anaemia are closely related, with anaemia being both a common complication in addition to being a marker of disease progression.(22, 23) HIV/AIDS-related anaemia is more common in sub-Saharan Africa.
• The mechanism of HIV/AIDS-related anaemia is complex, and beyond the scope of this review.
• Anaemia is known directly result from HIV infection and anaemia of chronic disease, and indirectly affected by antiretroviral therapy and AIDS-related illnesses. (23).

Genetic causes

• Haemoglobin disorders affect populations in LMICs disproportionately more than other areas of the world, particularly Africa and South East Asian regions where 18.2% and 6.6% of the population, respectively, carry a significant haemoglobin variant, as a result affecting more than 7% of pregnant women worldwide.
• Values of haemoglobin below this disease defining threshold necessitate treatment, but cannot suggest what treatment should be offered, as a fall in haemoglobin is multifactorial.
• There is increasing awareness that the evidence base behind widely used thresholds for anaemia and iron biomarkers in pregnancy is poor.
• Currently there is ongoing work by WHO to look at the evidence behind anaemia defining haemoglobin levels used in clinical practice and research, which may change the tide in this area.
• As a consequence, guidelines and policy may be frustratingly vague.

What next?

• There are emerging Australian data suggesting testing and treatment of non-anaemic iron deficiency would be beneficial in reducing transfusion post-delivery, however this has not been tested in trial settings.
• (38) There are limited data on the use of other laboratory tests as screening tools.
• In routine clinical practice a low haemoglobin, mean cell volume (MCV) and mean cell haemoglobin (MCH), and mean cell haemoglobin concentration (MCHC) are suggestive of iron deficiency, but need cautious interpretation.
• Further testing and cost effectiveness analyses would be required before this could be implemented outside of research.
• (28) Other markers such as serum hepcidin (a key homeostatic regulator of iron metabolism) are currently being tested in pregnancy settings, but are not routinely available for clinical use. (41).

Conclusion

• Haemoglobin is still widely used as a screening tool for anaemia in pregnancy.
• In the UK, a fall in haemoglobin is most commonly as a result of iron deficiency and so current guidelines recommend oral iron therapy as first line management.
• In LMIC settings, iron supplementation alone is unlikely to improve anaemia prevalence.

Figures

Fig. 2. Percentages of secondary organic carbon (SOC) in organic carbon (OC) and fossil fuelderived SOC (OCf_sec) in SOC with the increase of PM2.5 concentrations.

Table 1. Information of the samples selected for radiocarbon measurements.

Table 2. Relative contribution of fossil fuel sources to different carbon fractions (%).

Fig. 1. Total carbon composition patterns regarding emission sources and carbon species. (A): average (n = 12); (B): individual samples and the meteorological parameters.

Table 4. Concentrations (ng/m3) for monoterpene, isoprene, β-carophyllenene and aromatic tracer compounds observed at Wuhan (central China) in winter.

Table 3. Relative fossil fuel source contributions (%) to carbon fractions around the world.

Frequently asked questions

Q1. What are the contributions in "The importance of non-fossil sources in carbonaceous aerosols in a megacity of central china during the 2013 winter haze episode: a source apportionment constrained by radiocarbon and organic tracers" ?

The importance of non-fossil sources in carbonaceous aerosols in a megacity of central China during the 2013 winter haze episode: A source apportionment constrained by radiocarbon and organic tracers Junwen Liu a, b, Jun Li a, *, Matthias Vonwiller b, c, Di Liu a, Hairong Cheng d, Kaijun Shen a, Gary Salazar b, Konstantinos Agrios b, c, Yanlin Zhang b, c, 1, Quanfu He a, Xiang Ding a, Guangcai Zhong a, Xinming Wang a, Sönke Szidat b, * *, Gan Zhang a a State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China b Department of Chemistry and Biochemistry & Oeschger Centre for Climate Change Research, University of Bern, Berne, 3012, Switzerland c Laboratory of Radiochemistry, Paul Scherrer Institute, Villigen-PSI, 5232, Switzerland d Department of Environmental Engineering, School of Resource and Environmental Science, Wuhan University, Wuhan, 430079, China * Corresponding author. 

Q2. What is the main factor leading to the formation of this haze?

Using an aerodyne aerosol chemical speciation monitor, Sun et al. (2014) found that stagnant meteorological conditions, coal combustion, secondary production, and regional transport were the main factors leading to the formation of this haze in Beijing. 

Q3. Why did the public, government, and scientists raise concerns about the haze?

Because a high PM2.5 loading can cause a reduction in visibility, climate changes, and human respiratory-cardiovascular diseases (Brunekreef and Holgate, 2002; Menon et al., 2002; Deng et al., 2008; Wang et al., 2014b), many concerns were raised by the public, government, and scientists. 

Q4. What are the sources of carbon in the atmosphere?

These carbon particles in the atmosphere have two sources: fossil fuel (FF, e.g., from traffic exhaust, coal combustion, industry) and non-fossil (NF, e.g., from open/forest fire, biofuel burning, biogenic emission) emissions. 

Q5. What is the source-apportionment method for OC?

A source-apportionment method for OC, including primary and secondary sources, was implemented using the measured carbon fractions, anhydrosugars, and 14C isotopic signals. 

Q6. What is the composition of the gross domestic product in Wuhan?

According to the annual report of the Editorial Department of Wuhan Statistical Yearbook-2014, the gross domestic product was composed of agriculture (3.7%), industry (48.6%), and other sectors (47.7%). 

Q7. What is the contribution of FF to EC?

Andersson et al. (2015) found that during this haze period FF sources on average contributed 74%, 68% and 68% to EC in Beijing, Shanghai and Guangzhou, respectively. 

Q8. What is the origin of haze particles in Wuhan?

To determine the origins of haze particles, the authors measured 14C isotopic signals and unique organic tracers in PM2.5 samples with various levels in Wuhan (Fig. S1), the largest (~550 km2) and most densely populated metropolis (~10 million) in central China. 

Q9. What was the RSD for the WSOC and TC measurements?

Values of fm for WSOC and TC were calculated from the isotopic mass conservation, and the fm(OC) values reported here were corrected by a field blank (0.45 µg C/cm2; fm = 0.61 ± 0.02). 

Q10. What is the effect of biomass burning on the haze phenomenon in china?

These results suggest that biomass burning is an important driver for the haze phenomenon in Chinese cities, which probably because the burning of biofuel is still very extensive in China, especially in winter season. 

Q11. What is the reason for the haze crisis?

this large-scale haze crisis was very likely caused by the convergence of materials from numerous point sources in regions with different sources. 

Q12. What is the effect of BB on OCnf_sec?

These results show a significantly dominant influence of BB on OCnf_sec during this long-lasting winter haze, corresponding to the very low levels of biogenic VOCs in winter. 

Q13. What is the important factor in the calculation of SOCbb?

In this study, a rough estimation of SOCbb (SOCbb = OCnf_sec - SOCbio) was obtained based on the combination of 14C and molecular markers of biogenic emissions (Table S2).