Dong Chen

University of Maryland, College Park

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Co-Authors

Tatiana Loboda

University of Maryland, College Park

Gerald V. Frost

Alaska Biological Research (United States)

Nancy H. F. French

Michigan Technological University

Logan T. Berner

Northern Arizona University

Elizabeth Hoy

Goddard Space Flight Center

Randi Jandt

University of Alaska Fairbanks

S. J. Goetz

Northern Arizona University

Liza K. Jenkins

Michigan Technological University

Jiaying He

Institute of Geographic Sciences and Natural Resources Research

Scott J. Davidson

University of Waterloo

Cooperative Institutions

Chinese Academy of Sciences

University of Maryland, College Park

University of Chinese Academy of Sciences

Ministry of Natural Resources

Nanjing University

Nanjing University of Information Science and Technology

Second Institute of Oceanography

State Key Laboratory of Pollution Control and Resource Reuse

China Meteorological Administration

Shanghai Jiao Tong University

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DFT investigations on the mechanisms and kinetics for the DMS + O₃ reaction

Journal of Physical Organic Chemistry (2023)

Shuangjun Wang Hui Zhao Dong Chen Chenggang Lu Yizhen Tang

Abstract The potential energy surface (PES) for the reaction of ozone with dimethyl sulfide (DMS) was calculated at the CCSD(T)/6‐311++G(3df,2pd)//M06‐2X/6‐311++G(d,p) levels of theory. Result shows that on the singlet PES the addition–elimination mechanism is dominant, and H‐abstraction mechanism is less competitive. The major channel starts from the addition of ozone and DMS leading to a weak intermediate IM1, which decomposes subsequently to DMSO and 1 O 2 via a barrier around 38.8 kJ/mol. With a barrier of 64.0 kJ/mol, the formation of HO 3 + CH 3 SCH 2 via H‐abstraction mechanism is subdominant. Besides, DMSO + 1 O 2 can take place further reactions to produce several products. The substitution mechanism was located on the triplet PES, however, with a rather high barrier it is negligible. Furthermore, the rate constants for the two channels leading to DMSO + 1 O 2 and HO 3 + CH 3 SCH 2 were calculated from 200 to 1000 K. The total rate constant is 1.13 × 10 ‐20 cm 3 ·molecule ‐1 ·s ‐1 at 298 K and 1 atm, in good agreement with previous experimental data. The overall rate constants are positive temperature dependent in the whole temperature range.

Atmospheric temperature range

Dimethyl sulfide

Potential energy surface

10.1002/poc.4558

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Impacts of wildfire and landscape factors on organic soil properties in Arctic tussock tundra

Environmental Research Letters (2021)

Jiaying He Dong Chen Liza K. Jenkins Tatiana Loboda

Abstract Tundra ecosystems contain some of the largest stores of soil organic carbon among all biomes worldwide. Wildfire, the primary disturbance agent in Arctic tundra, is likely to impact soil properties in ways that enable carbon release and modify ecosystem functioning more broadly through impacts on organic soils, based on evidence from a recent extreme Anaktuvuk River Fire (ARF). However, comparatively little is known about the long-term impacts of typical tundra fires that are short-lived and transient. Here we quantitatively investigated how these transient tundra fires and other landscape factors affected organic soil properties, including soil organic layer (SOL) thickness, soil temperature, and soil moisture, in the tussock tundra. We examined extensive field observations collected from nearly 200 plots across a wide range of fire-impacted tundra regions in AK within the scope of NASA’s Arctic Boreal Vulnerability Experiment. We found an overall shallower SOL in our field regions (∼15 cm on average) compared to areas with no known fire record or the ARF (∼20 cm or thicker), suggesting that estimations based on evidence from the extreme ARF event could result in gross overestimation of soil organic carbon (SOC) stock and fire impacts across the tundra. Typical tundra fires could be too short-lived to result in substantial SOL consumption and yield less robust results of SOL and carbon storage. Yet, repeated fires may amount to a larger amount of SOC loss than one single severe burning. As expected, our study showed that wildfire could affect soil moisture and temperature in the tussock tundra over decades after the fire, with drier and warmer soils found to be associated with more frequent and severe burnings. Soil temperature was also associated with vegetation cover and air temperature.

Tussock

Soil carbon

Arctic vegetation

Biome

10.1088/1748-9326/ac1192

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Citations (20)

CO2 efflux from two biologically-crusted soils in response to drying-rewetting cycles with different frequencies in the Tengger Desert.

Shengtaixue zazhi (2015)

Dong Chen Rong Zhao Xiaojun Li Yang Zhao Yang Hao-Tian

Desert (philosophy)

Efflux

Source

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Citations (1)

Transcriptional Analysis of Microcystis aeruginosa Co-Cultured with Algicidal Bacteria Brevibacillus laterosporus

International Journal of Environmental Research and Public Health (2021)

Yulei Zhang Dong Chen Ning Zhang Feng Li Xiaoxia Luo

Harmful algal blooms caused huge ecological damage and economic losses around the world. Controlling algal blooms by algicidal bacteria is expected to be an effective biological control method. The current study investigated the molecular mechanism of harmful cyanobacteria disrupted by algicidal bacteria. Microcystis aeruginosa was co-cultured with Brevibacillus laterosporus Bl-zj, and RNA-seq based transcriptomic analysis was performed compared to M. aeruginosa, which was cultivated separately. A total of 1706 differentially expressed genes were identified, which were mainly involved in carbohydrate metabolism, energy metabolism and amino acid metabolism. In the co-cultured group, the expression of genes mainly enriched in photosynthesis and oxidative phosphorylation were significantly inhibited. However, the expression of the genes related to fatty acid synthesis increased. In addition, the expression of the antioxidant enzymes, such as 2-Cys peroxiredoxin, was increased. These results suggested that B. laterosporus could block the electron transport by attacking the PSI system and complex I of M. aeruginosa, affecting the energy acquisition and causing oxidative damage. This further led to the lipid peroxidation of the microalgal cell membrane, resulting in algal death. The transcriptional analysis of algicidal bacteria in the interaction process can be combined to explain the algicidal mechanism in the future.

Microcystis aeruginosa

Microcystis

10.3390/ijerph18168615

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Citations (11)

Spatio-temporal patterns of optimal Landsat data for burn severity index calculations: Implications for high northern latitudes wildfire research

Remote Sensing of Environment (2021)

Dong Chen Cheng Fu Joanne Hall Elizabeth Hoy Tatiana Loboda

10.1016/j.rse.2021.112393

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Citations (16)

Long-Term Record of Sampled Disturbances in Northern Eurasian Boreal Forest from Pre-2000 Landsat Data

Remote Sensing (2014)

Dong Chen Tatiana Loboda Saurabh Channan A. Hoffman‐Hall

Stand age distribution is an important descriptor of boreal forest structure, which is directly linked to many ecosystem processes including the carbon cycle, the land–atmosphere interaction and ecosystem services, among others. Almost half of the global boreal biome is located in Russia. The vast extent, remote location, and limited accessibility of Russian boreal forests make remote sensing the only feasible approach to characterize these forests to their full extent. A wide variety of satellite observations are currently available to monitor forest change and infer its structure; however, the period of observations is mostly limited to the 2000s era. Reconstruction of wall-to-wall maps of stand age distribution requires merging longer-term site observations of forest cover change available at the Landsat scale at a subset of locations in Russia with the wall-to-wall coverage available from coarse resolution satellites since 2000. This paper presents a dataset consisting of a suite of multi-year forest disturbance samples and samples of undisturbed forests across Russia derived from Landsat Thematic Mapper and Enhanced Thematic Mapper Plus images from 1985 to 2000. These samples provide crucial information regarding disturbance history in selected regions across the Russian boreal forest and are designed to serve as a training and/or validation dataset for coarse resolution data products. The overall accuracy and Kappa coefficient for the entire sample collection was found to be 83.98% and 0.83%, respectively. It is hoped that the presented dataset will benefit subsequent studies on a variety of aspects of the Russian boreal forest, especially in relation to the carbon budget and climate.

Biome

Thematic Mapper

10.3390/rs6076020

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Assessment of land degradation in Guizhou Province, Southwest China using AVHRR/NDVI and MODIS/NDVI data

Qiuhao Huang Manchun Li Chong Chen Kun Mao Zhenjie Chen

Monitoring and assessing land degradation is important to local sustainable development in Guizhou province, Southwest China, where limestone distributed about 61.7 %. Using the 1 km Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index (AVHRR/NDVI) data (1992-1993) and 500 m, Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index (MODIS/NDVI) (2002-2003) in growing seasons (AprilSeptember), this paper assessed land degradation in Guizhou Province, Southwest China from 1992 to 2003. Comparison of NDVI change in limestone-distributed area and non-limestone distributed area in 7 biophysical geography zones were also performed. The final result shows the spatial pattern of land degradation during the past 10 years and suggests that lime-distributed areas are easily degraded than non-limestone distributed areas. All these finding may serve as a strong basis for decision making in regard to land resource management and environmental rehabilitation.

Advanced very-high-resolution radiometer

Moderate-resolution imaging spectroradiometer

10.1109/geoinformatics.2010.5568119

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Seafloor Hydrothermal Activity around a Large Non-Transform Discontinuity along Ultraslow-Spreading Southwest Indian Ridge (48.1–48.7° E)

Journal of Marine Science and Engineering (2021)

Dong Chen Chunhui Tao Yuan Wang Sheng Chen Jin Liang

Non-transform discontinuity (NTD) is one category of tectonic units along slow- and ultraslow-spreading ridges. Some NTD-related hydrothermal fields that may reflect different driving mechanisms have been documented along slow-spreading ridges, but the discrete survey strategy makes it hard to evaluate the incidence of hydrothermal activity. On ultraslow-spreading ridges, fewer NTD-related hydrothermal activities were reported. Factors contributing to the occurrence of hydrothermal activities at NTDs and whether they could be potential targets for hydrothermal exploration are poorly known. Combining turbidity and oxidation reduction potential (ORP) sensors with a near-bottom camera, Chinese Dayang cruises from 2014 to 2018 have conducted systematic towed surveys for hydrothermal activity around a large NTD along the ultraslow-spreading Southwest Indian Ridge (SWIR, 48.1–48.7° E). Five new potential hydrothermal anomaly sites (2 inferred and 3 suspected) of high or low temperature and the previously inferred Sudi hydrothermal field occurred in diverse morphotectonic settings along a 78 km long ridge axis. The calculated vent frequency (Fs, sites/100 km) was ~7.7 over the entire study area, higher than the modified value (Fs ≈ 6.5) between 48 and 52° E of SWIR. Even only for the 54 km long large NTD, three hydrothermal anomaly sites yielded an Fs of ~5.6, which is higher than that of most ridge sections and is comparable to some fast-spreading ridges with high-resolution surveys. This indicates that NTDs along ultraslow-spreading ridges could be promising areas in fertilizing hydrothermal activities. Moreover, the deeply penetrating faults on the rift valley walls and strain-focused areas may contribute to the formation of NTD-related hydrothermal circulations. We suggest that NTDs along ultraslow-spreading ridges may be potential targets for further exploration of hydrothermal activities and seafloor sulfide deposits.

Seafloor Spreading

Discontinuity (linguistics)

10.3390/jmse9080825

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Citations (3)

Disturbances in North American boreal forest and Arctic tundra: impacts, interactions, and responses

Environmental Research Letters (2022)

Adrianna Foster Jonathan Wang Gerald V. Frost Scott J. Davidson Elizabeth Hoy

Abstract Ecosystems in the North American Arctic-Boreal Zone (ABZ) experience a diverse set of disturbances associated with wildfire, permafrost dynamics, geomorphic processes, insect outbreaks and pathogens, extreme weather events, and human activity. Climate warming in the ABZ is occurring at over twice the rate of the global average, and as a result the extent, frequency, and severity of these disturbances are increasing rapidly. Disturbances in the ABZ span a wide gradient of spatiotemporal scales and have varying impacts on ecosystem properties and function. However, many ABZ disturbances are relatively understudied and have different sensitivities to climate and trajectories of recovery, resulting in considerable uncertainty in the impacts of climate warming and human land use on ABZ vegetation dynamics and in the interactions between disturbance types. Here we review the current knowledge of ABZ disturbances and their precursors, ecosystem impacts, temporal frequencies, spatial extents, and severity. We also summarize current knowledge of interactions and feedbacks among ABZ disturbances and characterize typical trajectories of vegetation loss and recovery in response to ecosystem disturbance using satellite time-series. We conclude with a summary of critical data and knowledge gaps and identify priorities for future study.

10.1088/1748-9326/ac98d7

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Citations (39)

Strong cooling induced by stand-replacing fires through albedo in Siberian larch forests

Scientific Reports (2018)

Dong Chen Tatiana Loboda Tao He Yi Zhang Shunlin Liang

Abstract The Siberian larch forests, taking up about a fifth of the global boreal biome, are different from the North American boreal forests in that they generally do not undergo a secondary succession. While wildfires in the boreal forests in North America have been shown to exert a cooling effect on the climate system through a sharp increase in surface albedo associated with canopy removal and species composition change during succession, the magnitude of the surface forcing resulting from fire-induced albedo change and its longevity in Siberia have not been previously quantified. Here we show that in contrast to previous expectations, stand-replacing fires exert a strong cooling effect similar in magnitude to that in North America. This cooling effect is attributable to the increase in surface albedo during snow-on periods. However, the observed earlier snowmelt in the region, and subsequently a longer snow-free season, has resulted in a warming effect which has the potential to offset the fire-induced cooling. The net albedo-induced forcing of the Siberian larch forests in the future would hinge on the interaction between the fire-induced cooling effect and the climate-induced warming effect, both of which will be impacted by the expected further warming in the region.

Snowmelt

Albedo (alchemy)

Biome

Forcing (mathematics)

10.1038/s41598-018-23253-1

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Citations (34)