Institute of Earth Environment
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Impacts of Biomass Burning in Peninsular Southeast Asia on PM2.5 Concentration and Ozone Formation in Southern China During Springtime-A Case Study
No full textBiomass burning (BB) affects fine particulate matter (PM2.5) concentration and ozone (O-3) formation by emitting gaseous precursors and primary aerosols. The Impacts of BB in peninsular Southeast Asia (BB-PSEA) on PM2.5 concentration and O-3 formation in southern China are evaluated using a source-oriented WRF-Chem model to simulate an air pollution episode from March 21 to March 25, 2015. The source-oriented model separates the emissions from BB-PSEA and other sources and can evaluate the effects of aerosol-radiation interactions (ARIs) and aerosol-photolysis interactions (APIs) from BB-PSEA. Comparisons with observations reveal that the model performs well in simulating the air pollution episode. Sensitivity experiments show that BB-PSEA increases PM2.5 concentrations on the regional average by 39.3 mu g m(-3) (68.0%) in Yunnan Province (YNP) and 8.4 mu g m(-3) (24.1%) in other downwind areas (ODAs) in southern China, including the provinces of Guizhou, Guangxi, Hunan, Guangdong, Jiangxi, Fujian, and Zhejiang. PM2.5 enhancement is mainly attributed to primary aerosols in YNP and to secondary aerosols in ODA. BB-PSEA increases O-3 concentrations by 18.1 mu g m(-3) (19.4%) in YNP and decreases O-3 concentrations by 3.7 mu g m(-3) (5.3%) in ODA. The O-3 increase in YNP is attributed to the gaseous emissions of BB-PSEA, and the O-3 decrease in ODA is caused by the effects of ARI and API from BB-PSEA. NH3 emissions from BB-PSEA play a key role in enhancing secondary inorganic aerosols in southern China and determining increases in PM2.5 concentrations in ODA
Pollution characteristics, spatial distribution, and source identification of heavy metals in road dust in a central eastern city in China: a comprehensive survey
No full textRoad dust enriched with heavy metals (HMs) is detrimental to ecosystems and human health in urban environments. In this study, it is to explore the concentrations, spatial distribution, contaminated levels, and source identification of six HMs (lead (Pb), zinc (Zn), copper (Cu), cobalt (Co), chromium (Cr), and nickel (Ni)) based on 130 road dusts in Xinyang urban area. The results indicated that the contents of Pb, Zn, Cu, and Co were higher than the background values in more than 99% of the samples, and their average concentrations were 15.2, 9.2, 8.6, and 6.3 times the background value, respectively. The spatial distribution of high-value areas for Pb, Zn, Cu, Cr, and Ni was more similar, which was associated with traffic density near major roads and population and settlement patterns. Co was relatively different from the five elements, which was distributed in the areas of residence, commerce, and industry. Furthermore, the investigated HMs were clearly polluted, with Pb, Zn, Cu, and Co indicating high levels of contamination, while Cr and Ni were moderately polluted. The comprehensive pollution of the six HMs was mostly moderate to heavy in this study. Moreover, three sources of HMs designated by correlation analysis (CA) and principal component analysis (PCA) were mixed traffic emissions and industrial waste for Cu and Cr; automotive emissions for Pb, Ni, and Zn; and mixed domestic waste and industrial activities for Co, with contributions of 42.3%, 46.4%, and 11.3% via the principal component analysis-multiple linear regression (PCA-MLR) model. The multi-factor index for pollution assessment combined with source identification is extremely effective and practical for providing reliable data support and a theoretical reference for pollution monitoring and governance
Pollution characteristics, spatial distribution, and source identification of heavy metals in road dust in a central eastern city in China: a comprehensive survey
No full textRoad dust enriched with heavy metals (HMs) is detrimental to ecosystems and human health in urban environments. In this study, it is to explore the concentrations, spatial distribution, contaminated levels, and source identification of six HMs (lead (Pb), zinc (Zn), copper (Cu), cobalt (Co), chromium (Cr), and nickel (Ni)) based on 130 road dusts in Xinyang urban area. The results indicated that the contents of Pb, Zn, Cu, and Co were higher than the background values in more than 99% of the samples, and their average concentrations were 15.2, 9.2, 8.6, and 6.3 times the background value, respectively. The spatial distribution of high-value areas for Pb, Zn, Cu, Cr, and Ni was more similar, which was associated with traffic density near major roads and population and settlement patterns. Co was relatively different from the five elements, which was distributed in the areas of residence, commerce, and industry. Furthermore, the investigated HMs were clearly polluted, with Pb, Zn, Cu, and Co indicating high levels of contamination, while Cr and Ni were moderately polluted. The comprehensive pollution of the six HMs was mostly moderate to heavy in this study. Moreover, three sources of HMs designated by correlation analysis (CA) and principal component analysis (PCA) were mixed traffic emissions and industrial waste for Cu and Cr; automotive emissions for Pb, Ni, and Zn; and mixed domestic waste and industrial activities for Co, with contributions of 42.3%, 46.4%, and 11.3% via the principal component analysis-multiple linear regression (PCA-MLR) model. The multi-factor index for pollution assessment combined with source identification is extremely effective and practical for providing reliable data support and a theoretical reference for pollution monitoring and governance
Diverse Regional Sensitivity of Summer Precipitation in East Asia to Ice Volume, CO2 and Astronomical Forcing
No full textThe relative influence of insolation, CO2, and ice sheets on the East Asian summer monsoon (EASM) is not well understood especially at regional scale. Here a Gaussian emulator based on simulations with HadCM3 is used to quantitatively assess how astronomical forcing, CO2, and northern hemisphere ice sheets affect the variation of the summer precipitation over the last 800 ky. Our results show that in the EASM domain north of 25 degrees N, the variation of the summer precipitation is dominated by precession, leading to strong 23-ky cycles, while the ice sheets only modulate the effect of insolation by influencing the land-sea pressure gradient. In the southern part, ice sheets play a more important role, generating 100-ky cycles, through influencing the latitude of the Intertropical Convergence Zone and the Hadley cell. Obliquity and CO2 have little effect on the summer precipitation as compared to precession and ice sheets
Characteristics and sources of hourly elements in PM10 and PM2.5 during wintertime in Beijing
No full textCharacteristics and sources of ambient particle elements in urban Beijing were studied by hourly ob-servations in two size fractions (PM10 and PM2.5) during November and December 2017 using an online multi-element analyzer. The reconstructed oxide concentrations of 24 elements (from Al to Pb) comprise an appreciable fraction of PM10 and PM2.5, accounting for 37% and 17%, respectively on average. We demonstrate the benefit of using high-time-resolution chemical speciation data in achieving robust source apportionment of the total elemental PM10 (PM10el) and elemental PM2.5 (PM2.5el) mass using positive matrix factorization (PMF). Biomass burning, coal combustion, secondary sulfate, industry, non -exhaust traffic and dust were identified in both size fractions (with varying relative concentrations), which accounted on average for 4%, 12%, 5%, 2%, 14%, and 63%, respectively to the total PM10el, and 14%, 35%, 21%, 6%, 12% and 12%, respectively to the total PM2.5el. Biomass burning and coal combustion exhibited higher concentrations during haze episodes of the heating season. In contrast, secondary sulfate and industry contributed more to haze episodes during the non-heating season. The fractional contribution of dust was mostly high during clean days, while the fractional non-exhaust traffic emission contribution was similar throughout the measurement period. The non-exhaust traffic emissions contributed locally, while the remaining sources were dominated by neighboring areas. Furthermore, trajectory analysis showed that the origin of the industrial sources roughly agreed with the locations of the main point sources. Overall, this work provides detailed information on the characteristics of the elements during different haze events during heating and non-heating seasons. (C) 2021 The Author(s). Published by Elsevier Ltd
In situ synthesis of micro-plastics embedded sewage-sludge co-pyrolyzed biochar: Implications for the remediation of Cr and Pb availability and enzymatic activities from the contaminated soil
No full textCareful designing of biochar (BC) employing biological and industrial waste materials has gained much attention to improve soil health via reducing the bioavailability of heavy metals (HMs) in the contaminated-soil. Herein, a forty-day pot experiment was conducted to explore the influence of micro plastic (MP) embedded sewage-sludge (SS). The effects of SS and MP dosage ratios (0e15%) on the physicochemical properties of the modified-biochars were also studied with slow-pyrolyzed (SBC-500 degrees C) and flash-pyrolyzed biochar (FSBC-70 0 degrees C). Our investigations found remarkable positive synergistic effects for the SBC-15% involving increased soil pH, CEC, high carbon contents, and alleviation in Cr and Pb leaching than control and FSBC-70 0 degrees C. Besides, SBC-15% containing high carbon functional groups can effectively mitigate the Cr and Pb availability stress by intensifying the adsorption or passivation in the amended-soil, thereby, significantly reducing the Cr and Pb EDTA-extractable contents. Chemical fractionation analyses further confirmed that SBC-15% addition was more helpful for Cr and Pb immobilization and ultimately reducing transfer-rate, bioconcentration-factor, and translocation-factor as compared to FSBC-15% and control due to its higher alkalinity, surface area/porosity, and available carbon functional groups. The maize biomass (root and shoot) increased by more than 50%, and the activities of soil enzymes such as urease, alkaline phosphatase, and glucosidase enzyme activities were also enhanced. This ecologically feasible strategy would pave an efficient way to make full use of the SS and MP for the biochar synthesis with excellent soil remediation performance. (C) 2021 Elsevier Ltd. All rights reserved
Anthropogenic Influences on Heavy Precipitation during the 2019 Extremely Wet Rainy Season in Southern China
No full textAnthropogenic forcings have reduced the likelihood of heavy precipitation in southern China like the 2019 March-July event by about 60
Numerical study of SALSCS demonstration unit in Xi 'an, China, with non-uniform solar irradiation
No full textSolar-Assisted Large-Scale Cleaning System (SALSCS) is a new attempt to alleviate outdoor air pollution by using solar energy. A demonstration unit was built in Xi'an, China, in 2016. Field tests and numerical simulations were carried out on the demonstration unit in January 2017. Results show that the thermal airflow rate of the south collector is well predicted, while that of the north collector is seriously overestimated, with a deviation between the simulated value and the measured value being as larger as 47.07%. In this paper, an improved numerical simulation method considering the non-uniformity of solar irradiation, the effects of weather condition and the photovoltaic panels of the collector top is presented. Simulation results show that the deviation between the simulated thermal airflow rate of the north collector and the measured value is only 2.13%. Photovoltaic panels on the collector top have a little influence on the thermal airflow rate of the collectors. If the roof of the north and south collectors is covered with all photovoltaic panels, the thermal airflow rate will be reduced only by 6.93% and 7.99%, respectively. (C) 2021 Elsevier Ltd. All rights reserved
Potential Associations between Low-Level Jets and Intraseasonal and Semi-Diurnal Variations in Coastal Chlorophyll-A over the Beibuwan Gulf, South China Sea
No full textLow-level jet (LLJ) significantly affects the synoptic-scale hydrometeorological conditions in the South China Sea, although the impact of LLJs on the marine ecological environment is still unclear. We used multi-satellite observation data and meteorological reanalysis datasets to study the potential impact of LLJs on the marine biophysical environment over the Beibuwan Gulf (BBG) in summer during 2015-2019. In terms of the summer average, the sea surface wind vectors on LLJ days became stronger in the southwesterly direction relative to those on non-LLJ days, resulting in enhanced Ekman pumping (the maximum upwelling exceeds 10 x 10(-6) m s(-1)) in most areas of the BBG, accompanied by stronger photosynthetically active radiation (increased by about 20 mu mol m(-2) s(-1)) and less precipitation (decreased by about 3 mm day(-1)). These LLJ-induced hydrometeorological changes led to an increase of about 0.3 degrees C in the nearshore sea surface temperature and an increase of 0.1-0.5 mg m(-3) (decrease of 0.1-0.3 mg m(-3)) in the chlorophyll-a (chl-a) concentrations in nearshore (offshore) regions. Intraseasonal and diurnal changes in the incidence and intensity of LLJs potentially resulted in changes in the biophysical ocean environment in nearshore regions on intraseasonal and semi-diurnal timescales. The semi-diurnal peak and amplitude of chl-a concentrations on LLJ days increased with respect to those on non-LLJ days. Relative to the southern BBG, LLJ events exhibit greater impacts on the northern BBG, causing increases of the semi-diurnal peak and amplitude with 1.5 mg m(-3) and 0.7 mg m(-3), respectively. This work provides scientific evidence for understanding the potential mechanism of synoptic-scale changes in the marine ecological environment in marginal seas with frequent LLJ days
Variability of PDO identified by a last 300-year stalagmite delta O-18 record in Southwest China
No full textStalagmite oxygen isotope (delta O-18) record has been widely used in characterizing Asian Monsoon variations. In southwest (SW) China, although the stalagmite delta O-18 was usually suggested as a precipitation proxy, it remains a subject of debate. Here we present two replicated, high-precise-dated stalagmite delta O-18 records for the interval 1710-2003 AD from Yunnan province, SW China. The stalagmite delta O-18 shows no correlation with the local monsoon precipitation, but a significantly positive correlation with the Pacific Decadal Oscillation (PDO) index. It demonstrates that the stalagmite delta O-18 in SW China is most likely influenced by the atmospheric circulation associated with the PDO through the upstream depletion mechanism. During the warm (cold) PDO period, the deficit rainfall over India would make the delta O-18 of water vapor transporting to SW China less (more) negative due to the weaker Rayleigh distillation process, which would lead to the less (more) negative stalagmite delta O-18. Consequently, the stalagmite delta O-18 in SW China is suitable to reconstruct the PDO variations. It is important to note that the other factors, such as El Nino-Southern Oscillation (ENSO) or sea surface temperature (SST) also possibly affect the stalagmite delta O-18 in SW China, and the relationship between them requires further studies. (C) 2021 Elsevier Ltd. All rights reserved