Centennial records of PAHs and black carbon in Altay mountain peatlands, Xinjiang, China

Nana Luo,Rui Yu,Bolong Wen,Kunshan Bao,Yelebolat Tuoliuhan,Xingtu Liu

doi:10.5194/egusphere-egu21-1515

Abstract

&lt;p&gt;Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) are potentially proxies of changes in natural and human activities during the past century. It is important to identify historical BC sources and differentiate human activities contribution to BC in the environment. In this study, a 30 cm peat profile from the Jiadengyu (JDY) peatland in Altay Mountain was dated by the &lt;sup&gt;137&lt;/sup&gt;Cs and &lt;sup&gt;210&lt;/sup&gt;Pb methods. BC, total PAHs content and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;BC&lt;/sub&gt; in JDY peat were tested. The results showed that the TOC, BC and PAHS contents in JDY peat core were 17.09 ~ 47.16%, 1.14 ~ 67.138 mg/g and 260.58 ~ 950.98 ng/g, respectively. The value of &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;BC&lt;/sub&gt; ranged -31.5&amp;#8240; ~ -27.43&amp;#8240;, with an average of -30.52&amp;#8240;. The range of total PAHs concentrations in JDY peat core were between 260.59 ng/g and 950.98 ng/g. The BC was significantly correlated with PAHs and regional population.&amp;#160;The BC fluxes have slightly increased since 1900s with the increasing population and cultivate area, and more significantly in 1980s.&lt;strong&gt; &lt;/strong&gt;The burning of biomass and yak dung, fossil fuels, and human activities (mining, coking coal) may have important effects on the BC emission of soil in the Altay region. The change of BC and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;BC&lt;/sub&gt; reflected the change of local energy structure. With the regional reclamation increasing and environment- friendly industry developing, the BC source of JDY peatland is mainly the result of the interaction between biomass combustion and fossil fuel combustion.&lt;/p&gt;

Highlights

Black carbon (BC) is produced by incomplete combustion of fossil fuels or biomass in environment and plays an important role in the carbon biogeochemical process of ecosystem (Hammes et al, 2007; Meehl et al, 2008; Ramanathan and Carmichael, 2008)
The DBD and Ash decreased while total organic carbon (TOC) and WC increased from 1–7 cm and from 11–18 cm; DBD and Ash increased while TOC and WC decreased from 7–11 cm and from 18–30 cm (Fig. 2)
Because BC and polycyclic aromatic hydrocarbons (PAHs) were always co-emitted from the same pyrolysis sources, the proportion of different PAHs sources could be used to estimate the proportion of BC sources (Bucheli et al, 2004; Cao et al, 2020; Yunker et al, 2002)

Summary

Introduction

Black carbon (BC) is produced by incomplete combustion of fossil fuels or biomass in environment and plays an important role in the carbon biogeochemical process of ecosystem (Hammes et al, 2007; Meehl et al, 2008; Ramanathan and Carmichael, 2008). Global BC was emitted by 50–270 Tg C a− 1 as residues of vegetation fires (Kuhlbusch, 1995), and 4.4 Tg C a− 1 from fossil fuel consumption with a liner increase trend (Bond et al, 2007). The increased industrial and agricultural activities have significantly changed the global carbon cycle through the emission of greenhouse gases and BC particles (Hu et al, 2020; Kuhlbusch, 1995). Previous methods for identifying soil BC sources included potassium dichromic oxidation, 375°C thermal oxidation, Thermal-light transmission carbon analyzer (TOT) and Thermoscopic carbon analyzer (TOT/RT), ratio between BC and total organic carbon (TOC) analysis, stable carbon isotope analysis (δ13CBC) and scanning electron microscope observation (SEM) (Gao et al, 2014b; Li et al, 2019; Neupane et al, 2020). The diagnostic ratios of PAHs are useful for indicating the sources of PAHs, mainly by the ratios of Flt/(Flt + Pyr), BaA/(BaA + Chr) and Ant/(Ant + Phe) (Gao et al, 2018; Yunker et al, 2002)

Methods

Results

Discussion

Conclusion