| 41. |
- Berntell, Ellen, et al.
(författare)
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Mid-Pliocene West African Monsoon rainfall as simulated in the PlioMIP2 ensemble
- 2021
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 17:4, s. 1777-1794
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Tidskriftsartikel (refereegranskat)abstract
- The mid-Pliocene warm period (mPWP; ∼3.2 million years ago) is seen as the most recent time period characterized by a warm climate state, with similar to modern geography and ∼400 ppmv atmospheric CO2 concentration, and is therefore often considered an interesting analogue for near-future climate projections. Paleoenvironmental reconstructions indicate higher surface temperatures, decreasing tropical deserts, and a more humid climate in West Africa characterized by a strengthened West African Monsoon (WAM). Using model results from the second phase of the Pliocene Modelling Intercomparison Project (PlioMIP2) ensemble, we analyse changes of the WAM rainfall during the mPWP by comparing them with the control simulations for the pre-industrial period. The ensemble shows a robust increase in the summer rainfall over West Africa and the Sahara region, with an average increase of 2.5 mm/d, contrasted by a rainfall decrease over the equatorial Atlantic. An anomalous warming of the Sahara and deepening of the Saharan Heat Low, seen in >90 % of the models, leads to a strengthening of the WAM and an increased monsoonal flow into the continent. A similar warming of the Sahara is seen in future projections using both phase 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5). Though previous studies of future projections indicate a west–east drying–wetting contrast over the Sahel, PlioMIP2 simulations indicate a uniform rainfall increase in that region in warm climates characterized by increasing greenhouse gas forcing. We note that this effect will further depend on the long-term response of the vegetation to the CO2 forcing.
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| 42. |
- Botvinik-Nezer, Rotem, et al.
(författare)
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Variability in the analysis of a single neuroimaging dataset by many teams
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 582, s. 84-88
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Tidskriftsartikel (refereegranskat)abstract
- Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses(1). The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset(2-5). Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed. The results obtained by seventy different teams analysing the same functional magnetic resonance imaging dataset show substantial variation, highlighting the influence of analytical choices and the importance of sharing workflows publicly and performing multiple analyses.
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| 43. |
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| 44. |
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| 45. |
- Chen, Yongqin David, et al.
(författare)
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Multiscale streamflow variations of the Pearl River basin and possible implications for the water resource management within the Pearl River Delta, China
- 2010
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 226:1-2, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- Long monthly streamflow series of three control hydrological stations of the Pearl River basin were analyzed by using the scanning t-test and the scanning F-test. Possible implications of the changing properties of streamflow variations for the water resource management of the Pearl River Delta are also discussed. The results indicated that: 1) more complicated changes were observed in terms of the second center moment when compared to the first original moment More significant abrupt changes of the second center moment imply more sensitive response of streamflow stability to climate changes and human activities; 2) abrupt behaviors of the first (second) center moment of the streamflow variations tend to be more sensitive to climate changes and/or human activities in the larger river basin when compared to those in the smaller river basin. These phenomena are attributed to buffering functions of more storage space of longer river channel, and more complicated and longer runoff yield and concentration processes in the river basin of larger drainage area; 3) annual minimum streamflow of the Pearl River basin tends to be increasing. This will be helpful for better human mitigation of the salinity intrusion in dry seasons across the Pearl River Delta. Annual maximum streamflow, when compared to annual minimum streamflow, shows larger-magnitude variability reflected by larger standard deviation, implying unfavorable conditions for flood mitigation in the Pearl River Delta. The results of this paper are of scientific and practical merits for water resource management and sound human mitigation to water hazards across the Pearl River Delta, and also are a good case study for similar researches in other river deltas in the world under the changing environment. (C) 2009 Elsevier Ltd and INQUA. All rights reserved.
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| 46. |
- Cui, Song, et al.
(författare)
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Heavy Metals in Sediment from the Urban and Rural Rivers in Harbin City, Northeast China
- 2019
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 16:22
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Tidskriftsartikel (refereegranskat)abstract
- The concentrations and ecological risk of six widespread heavy metals (Cu, Cr, Ni, Zn, Cd and Pb) were investigated and evaluated in sediments from both urban and rural rivers in a northeast city of China. The decreasing trend of the average concentration of heavy metals was Zn > Cr > Cu > Pb > Ni > Cd in Majiagou River (urban) and was Zn > Cr > Pb > Cu > Ni > Cd in Yunliang River (rural). The results showed that the concentrations of Cd and Zn were significantly elevated compared to the environmental background value (p < 0.05). Half of all sampling locations were deemed 'contaminated' as defined by the improved Nemerow pollution index (P-N' > 1.0). Applying the potential ecological risk index (RI) indicated a 'high ecological risk' for both rivers, with Cd accounting for more than 80% in both cases. Source apportionment indicated a significant correlation between Cd and Zn in sediments (R = 0.997, p < 0.01) in Yunliang River, suggesting that agricultural activities could be the major sources. Conversely, industrial production, coal burning, natural sources and traffic emissions are likely to be the main pollution sources for heavy metals in Majiagou River. This study has improved our understanding of how human activities, industrial production, and agricultural production influence heavy metal pollution in urban and rural rivers, and it provides a further weight of evidence for the linkages between different pollutants and resulting levels of heavy metals in riverine sediments.
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| 47. |
- Cui, Song, et al.
(författare)
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Polycyclic aromatic hydrocarbons in fresh snow in the city of Harbin in northeast China
- 2019
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 215
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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.
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| 48. |
- Cui, Song, et al.
(författare)
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Spatial and temporal variations of open straw burning based on fire spots in northeast China from 2013 to 2017
- 2021
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 244
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Tidskriftsartikel (refereegranskat)abstract
- Open straw burning releases significant amounts of particulate matter (PM) and trace gases into the air and thus is an important source of atmospheric pollutants in China. In this study, based on fire spots in northeast China from 2013 to 2017, we analyzed pollution concentration degree (PCD) and pollution concentration period (PCP), and assessed spatial and temporal variations of open straw burning. Straw types and burning areas were then determined according to the distributions of fire spots and land use dataset. The amounts of several major atmospheric pollutants (PM10, PM25, CO, NOx and NMVOCs (non-methane volatile organic compounds)) emitted into the atmosphere from open straw burning were estimated according to crop production, Residue/Grain ratio (R/G), combustion efficiency and emission factor. Open straw burning occurred frequently in dry and paddy fields, mainly in areas of West and Northeast Heilongjiang Province, Midwest Jilin Province and Central Liaoning Province. The temporal variations of open straw burning tended to be dispersed with PCD varying from >0.8 during 2013-2015 to <0.4 during 2017 and PCP changing from 28.2 to 36.0 during autumn-winter seasons of 2013-2015 to 5.4-7.9 during winter-spring seasons of 2016-2017. During the five-year period (2013-2017), the total straw yield reached 628.7 million tons, of which 10.9 million tons were open burned in northeast China. The total amounts emitted from open straw burning were 108.9, 106.9, 552.9, 36.9 and 99.4 thousand tons for PM10, PM25, CO, NOx and NMVOCs, respectively. Among these emissions, corn straw burning contributed 81.7%, 81.6%, 71.4%, 86.8% and 74.9% while rice straw burning contributed 18.2%, 18.4%, 28.5%, 13.2% and 25.0%, respectively. Emissions from open straw burning have significant impacts on pollutants ambient concentrations, especially for PM2.5 in the autumn-winter seasons as indicated by their good correlations (p < 0.05).
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| 49. |
- Cui, Song, et al.
(författare)
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Understanding the risks from diffuse pollution on wetland eco-systems : The effectiveness of water quality classification schemes
- 2020
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Ingår i: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- Eco-environmental safety and health is an important concept for the protection of flora and fauna in the wetland eco-system. Identifying impacts of human activities on wetland ecology and risk factors of environmental decline have become significant components of habitat protection. In this study, the Qixing River wetland, one of the Ramsar Sites, was taken as the research area. Seven water quality indices, including dissolved oxygen (DO), chemical oxygen demand (COD), ammonia nitrogen (NH3 - N), total phosphorus (TP), total nitrogen (TN), nitrates and nitrites were monitored at fifteen sampling locations. Entropy weight-set pair analysis, combined with discriminant analysis, was used to identify the most sensitive indicators for changes in water quality. Average concentrations for the indicators measured were: DO 7.24 (4.64-9.98) mg/L; COD 21.67 (5-50) mg/L; NH3-N 1.09 (0.41-2.15) mg/L; TP 0.18 (0.10-0.73) mg/L; TN 1.38 (0.76-2.17) mg/L, nitrite 0.016 (ND - 0.030) mg/L and nitrate concentration was 0.420 (0.315-0.613) mg/L. Water quality was found to be poorest at locations closer to sources of diffuse pollution such as agricultural land. In contrast, the more remote buffer zone and core zone of the wetland was characterized by improved indicators of water quality. The results of entropy weight-set pair analysis showed that the overall water quality grade of Qixing River wetland conforms to Class III of the "Environmental Quality Standards for Surface Water" of China (GB3838-2002). Discriminant analysis indicated that TP was the main contributory factor to reduced water quality classification while COD, ammonia nitrogen and total nitrogen were the key drivers of improving water quality grade and responsible for the Class III award. The prominence of these indicators is indicative of long-term use of fertilizers and pesticides in agricultural production. The more remote core area of the wetland was less affected by human activities, reflected in improved water quality results. The results showed that entropy weight-set pair analysis coupled with discriminant analysis adds value to widely used water environment quality indices and helps identify the main environmental factors driving water quality classification. In the case of the Qixing River wetland, there is clear potential to protect wetland eco-system safety by improving the water quality classification and reforming agronomic and land management practices.
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| 50. |
- Feng, Boya, et al.
(författare)
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Structural and Functional Insights into the Mode of Action of a Universally Conserved Obg GTPase
- 2014
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 12:5, s. e1001866-
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Tidskriftsartikel (refereegranskat)abstract
- Obg proteins are a family of P-loop GTPases, conserved from bacteria to human. The Obg protein in Escherichia coli (ObgE) has been implicated in many diverse cellular functions, with proposed molecular roles in two global processes, ribosome assembly and stringent response. Here, using pre-steady state fast kinetics we demonstrate that ObgE is an anti-association factor, which prevents ribosomal subunit association and downstream steps in translation by binding to the 50S subunit. ObgE is a ribosome dependent GTPase; however, upon binding to guanosine tetraphosphate (ppGpp), the global regulator of stringent response, ObgE exhibits an enhanced interaction with the 50S subunit, resulting in increased equilibrium dissociation of the 70S ribosome into subunits. Furthermore, our cryo-electron microscopy (cryo-EM) structure of the 50S? ObgE? GMPPNP complex indicates that the evolutionarily conserved N-terminal domain (NTD) of ObgE is a tRNA structural mimic, with specific interactions with peptidyl-transferase center, displaying a marked resemblance to Class I release factors. These structural data might define ObgE as a specialized translation factor related to stress responses, and provide a framework towards future elucidation of functional interplay between ObgE and ribosome-associated (p) ppGpp regulators. Together with published data, our results suggest that ObgE might act as a checkpoint in final stages of the 50S subunit assembly under normal growth conditions. And more importantly, ObgE, as a (p) ppGpp effector, might also have a regulatory role in the production of the 50S subunit and its participation in translation under certain stressed conditions. Thus, our findings might have uncovered an under-recognized mechanism of translation control by environmental cues.
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