| 1. |
|
|
| 2. |
- Li, Furong, et al.
(författare)
-
A Review of Relative Pollen Productivity Estimates From Temperate China for Pollen-Based Quantitative Reconstruction of Past Plant Cover
- 2018
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 9
-
Forskningsöversikt (refereegranskat)abstract
- Model-based quantitative reconstruction of past plant cover in Europe has shown great potential for: (i) testing hypotheses related to Holocene vegetation dynamics, biodiversity, and their relationships with climate and land use; (ii) studying long term interactions between climate and land use. Similar model-based quantitative reconstruction of plant cover in China has been restricted due to the lack of standardized datasets of existing estimates of relative pollen productivity (RPP). This study presents the first synthesis of all RPP values available to date for 39 major plant taxa from temperate China and proposes standardized RPP datasets that can be used for model-based quantitative reconstructions of past plant cover using fossil pollen records for the region. We review 11 RPP studies in temperate China based on modern pollen and related vegetation data around the pollen samples. The study areas include meadow, steppe and desert vegetation, various woodland types, and cultural landscapes. We evaluate the strategies of each study in terms of selection of study areas and distribution of study sites; pollen- and vegetation-data collection in field; vegetation-data collection from satellite images and vegetation maps; and data analysis. We compare all available RPP estimates, select values based on precise rules and calculate mean RPP estimates. We propose two standardized RPP datasets for 31 (Alt1) and 29 (Alt2) plant taxa. The ranking of mean RPPs (Alt-2) relative to Poaceae (= 1) for eight major taxa is: Artemisia (21) > Pinus (18.4) > Betula (12.5) > Castanea (11.5) > Elaeagnaceae (8.8) > Juglans (7.5) > Compositae (4.5) > Amaranthaceae/Chenopodiaceae (4). We conclude that although RPPs are comparable between Europe and China for some genera and families, they can differ very significantly, e.g., Artemisia, Compositae, and Amaranthaceae/Chenopodiaceae. For some taxa, we present the first RPP estimates e.g. Castanea, Elaeagnaceae, and Juglans. The proposed standardized RPP datasets are essential for model-based reconstructions of past plant cover using fossil pollen records from temperate China.
|
|
| 3. |
- Algaba, Juan-Carlos, et al.
(författare)
-
Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
-
Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
|
|
| 4. |
- Cui, Song, et al.
(författare)
-
Modeling primary and secondary fractionation effects and atmospheric transport of polychlorinated biphenyls through single-source emissions
- 2019
-
Ingår i: Environmental Geochemistry and Health. - : Springer. - 0269-4042 .- 1573-2983. ; 41:5, s. 1939-1951
-
Tidskriftsartikel (refereegranskat)abstract
- The Chinese Gridded Industrial Pollutants Emission and Residue Model (ChnGIPERM) was used to investigate potential fractionation effects and atmospheric transport of polychlorinated biphenyls (PCBs) derived from single-source emissions in China. Modeling the indicative PCBs (CB28, CB101, CB153, and CB180) revealed spatiotemporal trends in atmospheric transport, gas/particle partitioning, and primary and secondary fractionation effects. These included the inference that the Westerlies and East Asian monsoons affect atmospheric transport patterns of PCBs by influencing the atmospheric transport time (ATT). In this study, dispersion pathways with long ATTs in winter tended to have short ones in summer and vice versa. The modeled partitioning of PCB congeners between gas and particles was mainly controlled by temperature, which can further influence the ATT. The potential for primary and secondary fractionation was explored by means of numerical simulations with single-source emissions. Within ChnGIPERM, these phenomena were mainly controlled by the temperature and soil organic carbon content. The secondary fractionation of PCBs is a slow process, with model results suggesting a timescale of several decades.
|
|
| 5. |
- Cui, Song, et al.
(författare)
-
Optimization preparation of biochar from garden waste and quantitative analysis for Cd2+ adsorption mechanism in aqueous solution
- 2024
-
Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6815 .- 2190-6823. ; 14:12, s. 12761-12773
-
Tidskriftsartikel (refereegranskat)abstract
- To develop a market for biochar, it is imperative that solutions are found to producing biochars that are both high performance and economically viable. While biochar performance can be enhanced via chemical modification, it is likely that optimization of pyrolysis time and temperature is a more cost-effective approach to enhancing performance. This was explored via the transformation of urban garden waste into biochar using a range of preparation conditions (heating temperature, residence time, and heating rate). Biochar yield and Cd2+ adsorption performance were optimized using response surface methodology. The "best compromise" yield and Cd2+ adsorption performance (49.9% and 40.0 mg/g, respectively) of garden waste biochar were achieved using preparation conditions of 398 degrees C, 10 degrees C/min, and 30 min. In addition, the quantification of adsorption mechanisms suggested mineral precipitation, ion exchange, functional group complexation, and physical adsorption, accounted for 47.9%, 41.5%, 10.3%, and 0.3% of total adsorbed Cd2+ in biochar, respectively. Overall, transformation of garden waste into adsorbents might offer a new market for the utilization of urban garden waste, especially given the size of this waste stream and the challenges it presents to municipal administrations.
|
|
| 6. |
- Cui, Song, et al.
(författare)
-
Polycyclic aromatic hydrocarbons in fresh snow in the city of Harbin in northeast China
- 2019
-
Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 215
-
Tidskriftsartikel (refereegranskat)abstract
- Characterizing levels of polycyclic aromatic hydrocarbons (PAHs) in snow and their toxicity is important for understanding snow scavenging of PAHs and associated human health and environmental risks in cold regions. A total of 48 fresh snow samples were collected from six precipitation events during the winter of 2014-2015 at eight (5 urban, 2 suburban and 1 rural) sites across the heavily industrialized and agricultural city of Harbin in northeast China, and were analyzed for the USEPA priority 16 PAHs. Concentrations of the sum of the 16 PAHs from individual snow samples ranged from 0.3 to 2549.6 pg L-1 or nearly four orders of magnitude. The arithmetic mean concentration (+/- standard deviation) of the 48 samples was 218.1 +/- 623.7 mu g L-1, and the median value was 10.7 mu g L-1. The most abundant PAHs averaged from all the samples were Pyrene (17.1%), followed by Phenanthrene (14.9%), Naphthalene (14.4%), and Fluoranthene (10.2%). The important carcinogenic Sigma(7)PAHs accounted for 58.4% of the total PAHs at locations directly impacted by road traffic. Source apportionment analysis using diagnostic ratios coupled with principal component analysis (PCA) indicated that coal and biomass combustion and vehicle exhausts are the major sources of PAHs in winter. Concentrations of PAHs in snow were significantly correlated with measured levels of PAHs in airborne particulate matter (PM2.5 (R = 0.857, p < 0.05); PM10 (R = 0.831, p < 0.05)), as well as with ambient temperature (R = -0.851, p < 0.05). Almost all (99%) of PAHs measured in the snow were present in particulate phase. The practice of clearing snow by removing it from urban areas and disposing it in suburban and rural areas may create a new pathway of exposure, which needs to be assessed further.
|
|
| 7. |
- Jiang, Fangyuan, et al.
(författare)
-
Relative pollen productivities of the major plant taxa of subtropical evergreen-deciduous mixed woodland in China
- 2020
-
Ingår i: Journal of Quaternary Science. - : John Wiley & Sons. - 0267-8179 .- 1099-1417. ; 35:4, s. 526-538
-
Tidskriftsartikel (refereegranskat)abstract
- Quantifying the relationship between pollen and vegetation is an essential step in the pollen-based quantitative reconstruction of past vegetation cover. In this study, we use the Extended R-Value (ERV) model and a modern dataset of pollen (collected from moss polsters) and related vegetation from 50 sites in the Daba Mountains (subtropical China) to (i) estimate the relevant source area of pollen (RSAP) of the moss samples and the relative pollen productivities (RPPs) of nine major plant taxa-characteristic of the region, and (ii) evaluate the obtained RPPs. The RSAP estimates of moss polsters vary between 225 and 610 m depending on the ERV submodels and models of pollen dispersal and deposition used. The RPP estimates are different from values published in previous studies from temperate and subtropical China. This may be explained by differences in methodology, climate and vegetation (species composition and spatial distribution), of which vegetation is probably the most important factor. The ranking of the RPP estimates for the nine taxa is Pinus > Juglandaceae > D - Quercus (deciduous Quercus) > Poaceae > Rosaceae > Cyperaceae > Anacardiaceae > Castanea > Fabaceae. We use a 'leave-one-out' cross-validation strategy and the Landscape Reconstruction Algorithm (LRA) for pollen-based reconstruction of regional and local plant cover to evaluate the ERV model-based RPP estimates. Both the REVEALS (Regional Estimates of VEgetation Abundance from Large Sites)-based and the LOVE (LOcal Vegetation Estimates)-based plant cover using the RPP estimates are closer to the modern vegetation composition than pollen percentages, thus confirming the applicability of the ERV model and the LRA approach in subtropical China.
|
|
| 8. |
- Shen, Qian, et al.
(författare)
-
The Genome of Artemisia annua Provides Insight into the Evolution of Asteraceae Family and Artemisinin Biosynthesis
- 2018
-
Ingår i: Molecular Plant. - : Cell Press. - 1674-2052 .- 1752-9867. ; 11:6, s. 776-788
-
Tidskriftsartikel (refereegranskat)abstract
- Artemisia annua, commonly known as sweet wormwood or Qinghao, is a shrub native to China and has long been used for medicinal purposes. A. annua is now cultivated globally as the only natural source of a potent anti-malarial compound, artemisinin. Here, we report a high-quality draft assembly of the 1.74-gigabase genome of A. annua, which is highly heterozygous, rich in repetitive sequences, and contains 63 226 protein-coding genes, one of the largest numbers among the sequenced plant species. We found that, as one of a few sequenced genomes in the Asteraceae, the A. annua genome contains a large number of genes specific to this large angiosperm clade. Notably, the expansion and functional diversification of genes encoding enzymes involved in terpene biosynthesis are consistent with the evolution of the artemisinin biosynthetic pathway. We further revealed by transcriptome profiling that A. annua has evolved the sophisticated transcriptional regulatory networks underlying artemisinin biosynthesis. Based on comprehensive genomic and transcriptomic analyses we generated transgenic A. annua lines producing high levels of artemisinin, which are now ready for large-scale production and thereby will help meet the challenge of increasing global demand of artemisinin.
|
|
