Molecular properties of ultrafiltered dissolved organic matter and dissolved black carbon in headwater streams as determined by pyrolysis-GC⿿MS

Abstract

This study aimed to assess the molecular properties of dissolved organic matter (DOM) and dissolved black carbon (DBC) using analytical pyrolysis (Py-GC-MS). The sample set was comprised of ultrafiltered DOM (UDOM) from North American headwater streams associated with Long Term Ecological Research network sites. Pyrolysis products for each UDOM sample were categorized as being sourced from non-pyrogenic sources and DBC. Major non-pyrogenic components of the headwater stream UDOM were comprised of phenolic compounds derived from lignin and chitin markers from microbial biomass, and their relative contributions indicated differences in organic matter dynamics of these ecosystems. The DBC pyrolyzates included benzene, PAHs and benzonitriles, which accounted for 12.5 ± 4.5 % of total quantified peak area (TPQA), and decreased in the order Alaskan boreal forest (19 %), Alaskan tundra (17 %), Appalachian deciduous forest (11 %), Colorado alpine tundra (9 %), Puerto Rican mountainous tropical rainforest (9 %) and Kansas tallgrass prairie (7 %). Pyrolysis products were compared to DBC content as determined by the benzenepolycarboxylic acid (BPCA) method. Although Py-GC-MS has quantitative limitations, this technique can detect weakly condensed and other DBC structures which fall outside of the BPCA analytical window.

Remobilization of polycyclic aromatic hydrocarbons and organic matter in seawater during sediment resuspension experiments from a polluted coastal environment: Insights from Toulon Bay (France)

“…Nonetheless, humic-like material was evidenced in these Toulon sediments by Dang et al (2014) and we can reasonably make the assumption of a high presence of sedimentary soot BC because of PAHs originating mainly from combustion-residue-sources (Fig. S2, Readman et al, 1987;Zhou et al, 1999) that can be both released in seawater during our SRE (Dong et al, 2016;Kaal et al, 2016).…”

“…This does not necessarily exclude the hypothesis of the third phase distribution for 5-6 ring PAHs, but rather suggests that the latter would occur from their interaction with other OM moieties. Since PAHs in sediment most likely originated from combustion processes, the mobility of 5-6 ring PAHs could be related preferentially to the release of dissolved black carbon (Kaal et al, 2016).…”

Transformation of dissolved organic matter in a constructed wetland: A molecular-level composition analysis using pyrolysis-gas chromatography mass spectrometry

“…Pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) is a tool for defining organic molecular structure. Because of its low selectivity, this system has been used to investigate the structure of organic matter in many environmental samples [13][14][15]. Schulten and Gleixner [13] classified pyrolyzed fragments into ten groups: carbohydrates, phenols and lignin monomers, lignin dimers, lipids, alkylaromatics, aromatic nitrogen compounds, sterols, peptides, suberin, and loosely bound fatty acids.…”

Molecular characterization of the thermally labile fraction of biochar by hydropyrolysis and pyrolysis-GC/MS

“…Moreover, the labile fraction, which evolves in the short-term during its storage in soil, can influence the soil microbial community structure [9], and therefore affect the functioning of the soil [10]. Biochar application on land may impact the carbon cycle in the ocean due to the mobility of the water soluble labile fraction [11,12]. The knowledge of recalcitrance of carbon in biochar and the potential contamination from labile components are crucial issues for evaluating the agroenvironmental impact of biochar.…”