Dissolved Organic Matter Characteristics and Composition of Saline Lakes in the Badain Jaran Desert, China

Zhang, Qiang; Wang, Yinghui; Zhang, Xiaolang; Mo, Xiaohan; Zhang, Peng; Li, Hailong; Jiao, Jiu Jimmy; He, Chen; Shi, Quan; Fu, Qinglong; Chen, Baiyang; Wang, Junjian

doi:10.1021/acsearthspacechem.3c00179

Cited by 3 publications

(1 citation statement)

References 88 publications

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“…Within the 965 halogenated organic molecules, a total of 541 molecules were further identified as chlorinated organic molecules (Supporting Figure S3), according to the assignment rule given in Section . This result is consistent with the preferential chlorination of DOM in brine lakes . Halogenated DOM molecules are widely presented in various environments and are majorly linked to disinfection byproducts during water disinfection with chlorine or chloramines. − Photochemical halogenation of natural DOM is another source of halogenated organic molecules in natural environments. , Specifically, the halogenated organic molecules could be produced through photochemical reactions of DOM with reactive halogen species, which are induced by reactive oxygen species (ROS) .…”

Section: Resultssupporting

confidence: 67%

The Hunt for Chemical Dark Matter across a River-to-Ocean Continuum

Cai,

Yao,

et al. 2024

Environ. Sci. Technol.

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Thousands of mass peaks emerge during molecular characterization of natural dissolved organic matter (DOM) using ultrahigh-resolution mass spectrometry. While mass peaks assigned to certain molecular formulas have been extensively studied, the uncharacterized mass peaks that represent a significant fraction of organic matter and convey biogenic elements and energy have been previously ignored. In this study, we introduce the term dark DOM (DDOM) for unassigned mass peaks and have explored its characteristics and environmental behaviors using a data set of 38 DOM extracts covering the Yangtze River-to-ocean continuum. We identified a total of 9141 DDOM molecules, which exhibited higher molecular weight and greater diversity than the DOM subset with assigned DOM formulas. Although DDOM contributed a smaller fraction of relative abundance, it significantly impacted the molecular weight and molecular composition of bulk DOM. A portion of DDOM with higher molecular weight was found to increase molecular abundance across the river-to-ocean continuum. These compounds could contain halogenated organic molecules and might have a high potential to contribute to the refractory organic carbon pool. With this study, we underline the contribution of dark matter to the total DOM pool and emphasize that more DDOM research is needed to understand its contribution to global biogeochemical cycles and carbon sequestration.

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Section: Resultssupporting

confidence: 67%

The Hunt for Chemical Dark Matter across a River-to-Ocean Continuum

Cai,

Yao,

et al. 2024

Environ. Sci. Technol.

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Aromatic Structures Govern the Formation of Chlorinated Byproducts in Dichlorine Radical Reactions

Guan,

Lei,

Fan

et al. 2024

Environ. Sci. Technol.

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Radical-induced disinfection byproduct (DBP) formation is drawing attention with increasing applications of advanced oxidation processes (AOPs). Cl 2•− represents one of the extensively generated radicals in AOPs, whose behavior in DBP formation remains unknown. In this study, we found that aromatic structures serve as the main DBP precursors in Cl 2•− reactions by employing diverse groups of model compounds. At a typical Cl 2exposure of 1.2 × 10 −9 M•s, the sum concentrations of 7 regulated aliphatic DBPs (e.g., trichloromethane, chloroacetic acids) are ∼0.10 to 0.48 μM for aromatic precursors and <0.05 μM for aliphatic ones. The DBP formation mechanisms from Cl 2 •− reactions involved the formation of chlorinated aromatics, radical-induced oxygen incorporation followed by ring cleavage, and the interactions of Cl 2•− with ring-cleavage intermediates. In reacting with DOM, Cl 2 •− reactions produced much fewer aliphatic DBPs (5% of the total organochlorine vs 40% for chlorination) and chloroacetic acids dominated the aliphatic DBPs (usually trihalomethane for chlorination), which can be well interpreted by the precursors and mechanisms proposed. This work comprehensively reveals the precursors, formation patterns, and mechanisms of DBPs during the less-studied Cl 2•− reactions, highlighting the importance of eliminating the aromatic structures of DOM before the AOPs.

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Characterization of bacterial community dynamics dominated by salinity in lakes of the Inner Mongolian Plateau, China

Xin,

Xiaohong,

Yujiao

et al. 2024

Front. Microbiol.

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Microorganisms in lakes are sensitive to salinity fluctuations. Despite extensive prior research on bacterial communities, our understanding of their characteristics and assembly mechanisms in lakes, especially in desert lakes with different salinities. To address this issue, we collected three samples from freshwater lakes, six from brackish lakes, and five from salt lakes in the Badanjilin Desert. The 16S rRNA gene sequencing was applied to investigate the bacterial interactions with rising salinity, community coexistence patterns, and assembly mechanisms. Our findings suggested that the increased lake salinity significantly reduces the bacterial community diversity and enhanced the community differentiation. Significant variations were observed in the contribution of biomarkers from Cyanobacteria, Chloroflexi, and Halobacterota to the composition of the lake bacterial communities. The bacterial communities in the salt lakes exhibited a higher susceptibility to salinity limitations than those in the freshwater and brackish lakes. In addition, the null modeling analyses confirmed the quantitative biases in the stochastic assembly processes of bacterial communities across freshwater, brackish, and saline lakes. With the increasing lake salinity, the significance of undominated and diffusion limitation decreased slightly, and the influence of homogenizing dispersal on community assembly increased. However, the stochasticity remained the dominant process across all lakes in the Badanjilin Desert. The analysis of co-occurring networks revealed that the rising salinity reduced the complexity of bacterial network structures and altered the interspecific interactions, resulting in the increased interspecies collaboration with increasing salinity levels. Under the influence of salinity stress, the key taxon Cyanobacteria in freshwater lakes (Schizothrix_LEGE_07164) was replaced by Proteobacteria (Thalassobaculum and Polycyclovorans) in brackish lakes, and Thermotogota (SC103) in salt lakes. The results indicated the symbiotic patterns of bacterial communities across varying salinity gradients in lakes and offer insights into potential mechanisms of community aggregation, thereby enhancing our understanding of bacterial distribution in response to salinity changes.

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Dissolved Organic Matter Characteristics and Composition of Saline Lakes in the Badain Jaran Desert, China

Cited by 3 publications

References 88 publications

The Hunt for Chemical Dark Matter across a River-to-Ocean Continuum

The Hunt for Chemical Dark Matter across a River-to-Ocean Continuum

Aromatic Structures Govern the Formation of Chlorinated Byproducts in Dichlorine Radical Reactions

Characterization of bacterial community dynamics dominated by salinity in lakes of the Inner Mongolian Plateau, China

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