scholarly journals Aerosol pH and its influencing factors in Beijing

2018 ◽  
Author(s):  
Jing Ding ◽  
Pusheng Zhao ◽  
Jie Su ◽  
Qun Dong ◽  
Xiang Du
Keyword(s):  
Inorganic Ions ◽  
Dilution Effect ◽  
Liquid Water Content ◽  
Factors Affecting ◽  
Aerosol Acidity ◽  
Four Seasons ◽  
Different Seasons ◽  
Fine Mode ◽  
Autumn And Winter ◽  
Physical And Chemical

Abstract. Acidity (pH) plays a key role in the physical and chemical behavior of aerosol and cannot be measured directly. In this work, aerosol liquid water content (ALWC) and size-resolved pH are predicted by thermodynamic model (ISORROPIA-II) in 2017 of Beijing. The mean aerosol pH over four seasons is 4.3±1.6 (spring), 4.5±1.1 (winter), 3.9±1.3 (summer), 4.1±1.0 (autumn), respectively, showing the moderate aerosol acidity. The aerosol pH in fine mode is in the range of 1.8 ~ 3.9, 2.4 ~ 6.3 and 3.5 ~ 6.5 for summer, autumn and winter, respectively. And coarse particles are generally neutral or alkaline. Diurnal variation of aerosol pH follows both aerosol components (especially the sulfate) and ALWC. For spring, summer and autumn, the averaged nighttime pH is 0.3~0.4 unit higher than that on daytime. Whereas in winter, the aerosol pH is relatively low at night and higher at sunset. SO42− and RH are two crucial factors affecting aerosol pH. For spring, winter and autumn, the effect of SO42− on aerosol pH is greater than RH, and it is comparable with RH in summer. The aerosol pH decreases with elevated SO42− concentration. As the NO3− concentration increases, the aerosol pH firstly increases and then decreases. Sulfate-dominant aerosols are more acidic with pH lower than 4, whereas nitrate-dominated aerosols are weak in acidity with pH ranges 3~5. In recent years, the dominance of NO3− in inorganic ions may be another reason responsible for the moderately acidic aerosol. ALWC has a different effect on aerosol pH in different seasons. In winter, the increasing RH could reduce the aerosol pH whereas it shows a totally reverse tendency in summer, and the elevated RH has little effect on aerosol pH in spring and autumn when the RH is between 30 % and 80 %. The dilution effect of ALWC on Hair+ is only obvious in summer. The elevated NH3 and NH4+ could reduce aerosol acidity by decreasing Hair+ concentration exponentially.

Year-Round Behavior of Micro-plastics in Coastline Sand

2021 ◽  
Vol 58 (2) ◽  
pp. 185-191
Author(s):  
Sara Seyfi ◽  
Homayoun Katibeh ◽  
Monireh Heshami
Keyword(s):  
Water Analysis ◽  
Caspian Sea ◽  
Optical Microscope ◽  
Chemical Processes ◽  
The Caspian Sea ◽  
Four Seasons ◽  
Microscope Images ◽  
Different Seasons ◽  
Physical And Chemical ◽  
Number Of Particles

This article aims to identify the behavior of light and heavy micro-plastics on the southern shore of the Caspian Sea during different seasons of the year. For this purpose, data from 15 sampling stations were gathered in four seasons, and subjected to various analyses after the samples were prepared. To separate light and heavy micro-plastics, the samples were washed with water. Analysis of TGA-DSC and FTIR imaging ‎was used to quantitatively and qualitatively identify microplastic samples and optical microscope images were used to quantify the number of particles. According to the results, the amount of light microplastics in the spring and winter is less than in the summer and autumn‎. In the spring, the highest levels of pollutants are PVC, PES, PET and PU. In the summer and autumn, the values of PE, PP, PA, PAT, PU and PVC are at a ‎relatively equal range. In the winter, most pollutants are PVC, PES, and PU.‎ In conclusion, PE, PP, PPA, and PET should be removed from the environment before they can be modified by physical and chemical processes.

scholarly journals Sensitivity study on polarized aerosol retrievals of PARASOL in Beijing and Kanpur

2011 ◽  
Vol 4 (5) ◽  
pp. 5773-5806 ◽  
Author(s):  
X. F. Gu ◽  
S. P. Wang ◽  
L. Fang ◽  
T. Yu ◽  
J. Gao
Keyword(s):  
Size Distribution ◽  
Sensitivity Study ◽  
Relative Difference ◽  
Aerosol Size Distribution ◽  
Retrieval Algorithm ◽  
Aerosol Retrieval ◽  
Different Seasons ◽  
Fine Mode ◽  
Retrieval Errors ◽  
Autumn And Winter

Abstract. Sensitivity study on the PARASOL aerosol retrieval algorithm over land is presented for aerosol mixtures composed of fine mode pollution particles combined with coarse mode desert dust. First an assessment of the PARASOL aerosol products during the period of 2005–2009 is investigated by comparison with AOD derived by AERONET (Aerosol Robotic Network) at Beijing and Kanpur. Validation against AERONET fine mode AOD shows an overall high correlation of R2 = 0.79 for Beijing and R2 = 0.83 for Kanpur. However, the PARASOL retrievals are found to underestimate aerosol optical depth by about 27% and 34% for Beijing and Kanpur, respectively. The AOD agreement is obviously poorer as compared to AERONET total AOD, showing underestimation by 60% and 67%. At both sites, the PARASOL retrieval algorithm performs better in autumn and winter seasons with the best appearing in autumn. As PARASOL aerosol algorithm is sensitive to the accumulation mode of the aerosol size distribution, we conduct study on the threshold radius of this fraction of size distribution, named as sensitive radius, for different seasons at both Beijing and Kanpur. The results show that the sensitive radius for polarized aerosol retrieval is 0.35 μm for all seasons. And the agreement is significantly improved by employing comparison against the AERONET AOD recomputed for radius <0.35 μm, showing a correlation coefficient (R2) of 0.82 with relative difference being 12% for Beijing and 0.87 with relative difference being 19% for Kanpur. The sensitivity study on uncertainty of PARASOL aerosol retrieval demonstrates that uncertainties caused by the algorithm-assumed refractive index and size distribution are significantly higher in spring than those of autumn and winter seasons. The aerosol retrieval errors caused by aerosol polarized phase function qa(Θ) for spring are found to be higher at Kanpur, due to the obviously higher content of coarse dust particles. For all seasons the aerosol retrieval errors contributed by uncertainty in qa(Θ) are much close to the total retrieval errors (accounts for about 65% to 94% in different seasons), indicating that the overestimate of qa(Θ) in PARASOL algorithm accounts for most of the underestimate of retrieved AOD at both sites. Investigation on the uncertainty of surface contribution shows that the surface model overestimates surface polarization from about 20% to 50% with the maximum uncertainties occurring in winter.

scholarly journals Aerosol pH and its driving factors in Beijing

2019 ◽  
Vol 19 (12) ◽  
pp. 7939-7954 ◽  
Author(s):  
Jing Ding ◽  
Pusheng Zhao ◽  
Jie Su ◽  
Qun Dong ◽  
Xiang Du ◽  
...  
Keyword(s):  
The United States ◽  
Driving Factors ◽  
High Temporal Resolution ◽  
Aerosol Formation ◽  
Ph Variation ◽  
Factors Affecting ◽  
The North ◽  
Aerosol Acidity ◽  
Coarse Mode ◽  
Four Seasons

Abstract. Aerosol acidity plays a key role in secondary aerosol formation. The high-temporal-resolution PM2.5 pH and size-resolved aerosol pH in Beijing were calculated with ISORROPIA II. In 2016–2017, the mean PM2.5 pH (at relative humidity (RH) > 30 %) over four seasons was 4.5±0.7 (winter) > 4.4±1.2 (spring) > 4.3±0.8 (autumn) > 3.8±1.2 (summer), showing moderate acidity. In coarse-mode aerosols, Ca2+ played an important role in aerosol pH. Under heavily polluted conditions, more secondary ions accumulated in the coarse mode, leading to the acidity of the coarse-mode aerosols shifting from neutral to weakly acidic. Sensitivity tests also demonstrated the significant contribution of crustal ions to PM2.5 pH. In the North China Plain (NCP), the common driving factors affecting PM2.5 pH variation in all four seasons were SO42-, TNH3 (total ammonium (gas + aerosol)), and temperature, while unique factors were Ca2+ in spring and RH in summer. The decreasing SO42- and increasing NO3- mass fractions in PM2.5 as well as excessive NH3 in the atmosphere in the NCP in recent years are the reasons why aerosol acidity in China is lower than that in Europe and the United States. The nonlinear relationship between PM2.5 pH and TNH3 indicated that although NH3 in the NCP was abundant, the PM2.5 pH was still acidic because of the thermodynamic equilibrium between NH4+ and NH3. To reduce nitrate by controlling ammonia, the amount of ammonia must be greatly reduced below excessive quantities.

scholarly journals Water Quality Assessment of the Central Himalayan Lake, Nainital

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Madhuben Sharma
Keyword(s):  
Water Quality ◽  
Water Quality Assessment ◽  
International Standards ◽  
Total Alkalinity ◽  
Central Himalayas ◽  
Four Seasons ◽  
Different Seasons ◽  
Physical And Chemical ◽  
Sediment Basin

The Nainital Lake, situated in the central Himalayas of India, is an important water body and a major tourist spot. This study aims to identify factors or processes that determine the water quality of the lake. For this purpose, water samples from two different points were collected—highly polluted (Mallital) and least polluted (Tallital)—to represent the actual level of pollution in the lake in four different seasons (January, April, July, and October). The collected samples were analyzed for different physical and chemical parameters. In order to assess the state of the lake’s water quality, the samples were compared with the standard water quality values. Turbidity, electrical conductivity, total alkalinity, and heavy metal (lead, iron, and copper) concentration were found to be above the desirable limit of the prescribed national and international standards in all four seasons at both Mallital and Tallital. Reasons affecting the water quality were found to be natural (thermal stratification and lead-bearing rocks) and anthropogenic (domestic sewage, runoff, and illegal construction activities in the vicinity of lake). Various lake restoration alternatives/interventions have been suggested that can lead to an improvement in the lake’s water quality, such as afforestation, phytoremediation, and sediment basin.

scholarly journals Temporal and spatial changes of macrobenthos communities in south east shores of the Caspian sea

2021 ◽  
Vol 34 (04) ◽  
pp. 1403-1412
Author(s):  
Nadia Javandel ◽  
Maryam Akhoundian
Keyword(s):  
Species Richness ◽  
Diversity Index ◽  
Sampling Period ◽  
The Caspian Sea ◽  
Four Seasons ◽  
Spatial Changes ◽  
Two Factors ◽  
Different Seasons ◽  
Autumn And Winter ◽  
The Impact

In this research, Sampling of macrobenthos of Mazandaran beaches was performed in 7 stations at two depths of 5 and 10 meters during four seasons in 2020 using a grab with 8 replications in each station. In this study, a total of 10472 individuals were counted, which belonging to 22 species from 13 families. The highest frequency of macrobenthos (648 ± 170.79) was observed in spring and the highest amount of biomass (36.21 ±2.5 gr / m2) was observed in winter. Moreover, the highest prevalence of macrobenthos predominant groups during the sampling period was observed in Bivalves (40%), Crustaceans (36%), Annelids (22%) and Gastropoda (2%), respectively.  The results of PERMANOVA analysis showed that the effect of two factors of season and depth impacted the biomass, abundance, species richness, species composition and community structure of macrobenthos significantly. Furthermore, the results showed that with increasing the depth from 5 to 10 meters, macrobenthos abundance increased by 4, 2, 1 and 9 times in spring, summer, autumn and winter, respectively. Moreover, increase in depth from 5 to 10m, the values of biomass and species richness have increased. In according to these results, it can be concluded that biomass and diversity index of macrobenthos communities change considerably in different seasons and depths. Therefore, natural changes of these variables should be considered when using these macrobenthos communities to assess the impact of environmental factors.

scholarly journals Effect of harvest season on the nutritional value of bee pollen protein

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0241393
Author(s):  
Saad N. Al-Kahtani ◽  
El-Kazafy Taha ◽  
Khalid Ali Khan ◽  
Mohammad Javed Ansari ◽  
Soha A. Farag ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nutritional Value ◽  
Nutritive Value ◽  
Bee Pollen ◽  
Four Seasons ◽  
Adult Humans ◽  
Different Seasons ◽  
Amino Acid Requirements ◽  
Limiting Amino Acid ◽  
Autumn And Winter

Bee pollen is a natural product that has valuable nutritional and medicinal characteristics and has recently garnered increasing attention in the food industry due to its nutritive value. Here, we harvested pollen loads from the Al-Ahsa oasis in eastern Saudi Arabia during spring, summer, autumn, and winter in 2018/2019 to compare the nutritional value of bee pollen protein with the amino acid requirements of honeybees and adult humans. Based on the nutritional value of bee pollen protein, the optimal season for harvesting bee pollen was determined. The composition of the bee pollen showed the highest contents of crude protein, total amino acids, leucine, glutamic acid, valine, isoleucine, threonine, and glycine in samples collected in spring. The highest contents of lysine, phenylalanine, threonine, tryptophan, arginine, tyrosine, and cysteine were observed in samples collected in winter. The highest contents of histidine, methionine, and serine were in samples collected in autumn. Moreover, the highest levels of aspartic acid, proline, and alanine were in samples collected in summer. Leucine, valine, lysine, histidine, threonine, and phenylalanine (except in autumn bee pollen) contents in pollen from all four seasons were above the requirements of honeybees. Leucine, valine, histidine, isoleucine (except in autumn bee pollen), lysine (except in spring and summer bee pollen), and threonine (except in winter and spring bee pollen) in all tested samples were above the requirements of adult humans. In comparison with the minimal amino acid requirements of adult humans and honeybees, the 1st limiting amino acid in bee pollen collected during the different seasons was methionine. Bee pollen collected during spring (March–May) and winter (December–February) can be considered a nutritive food source for adult humans and honeybees.

scholarly journals Seasonal Variations of the Urban Thermal Environment Effect in a Tropical Coastal City

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Yao Yuan ◽  
Chen Xi ◽  
Qian Jing ◽  
Ndayisaba Felix
Keyword(s):  
Land Surface ◽  
Thermal Environment ◽  
Shenzhen City ◽  
Four Seasons ◽  
Different Seasons ◽  
Urban Heat ◽  
Surface Urban Heat Island ◽  
Autumn And Winter ◽  
Urban Thermal Environment ◽  
The City

Shenzhen city was selected to analyze the Surface Urban Heat Island (SUHI) variations based on land surface temperature (LST) in four different seasons of 2015. UHI intensity (UHII) as an indicator of SUHI was established and the method of density segmentation was utilized to classify the SUHI after LSTs were normalized. The gravity center model of UHII and Moran’s I (a spatial autocorrelation index) were used to analyze the spatiotemporal variations of SUHI. Results indicated that LST was higher in the west than in the east of the city. The values of UHII were higher in spring and summer and lower in autumn and winter. Five profiles were drawn to analyze the distribution of UHII in different seasons, and it was found that the No. 1 path profiles, corresponding to the western urban development axis, had higher UHII than other path profiles. The center of UHII gravity shifts converged in the Longhua, Baoan, and Nanshan Districts throughout the four seasons and Moran’s I values were higher in summer and spring. From the UHII’s spatial distribution pattern analysis, a spatially discontinuous pattern was observed in four seasons; there was a compact pattern of high temperature zones.

Study on Seasonal Characteristics of PM 2.5 in Harbin

2011 ◽  
Vol 183-185 ◽  
pp. 1246-1249 ◽  
Author(s):  
Li Kun Huang ◽  
Guang Zhi Wang
Keyword(s):  
Coal Combustion ◽  
Industrial Emissions ◽  
Seasonal Characteristics ◽  
Four Seasons ◽  
Significant Seasonal Variation ◽  
Different Seasons ◽  
Natural Emissions ◽  
Seasonal Characteristic ◽  
Autumn And Winter ◽  
Distribution Trends

In order to investigate the seasonal characteristic of PM2.5, PM2.5 were collected in four seasons. This study investigates the elemental characteristics of PM2.5. The results show that the distribution trends of Ca, Na, and Mg are consistent and they are the highest in summer, lowest in winter. S is lower in summer and higher in autumn and winter, which is also caused by heating in autumn and winter. Si is higher in winter and lower in autumn, fly ash emissions from coal combustion is the main reason. Zn and K have a significant seasonal variation which is influenced by environmental factors in different seasons. Al and Fe mainly come from industrial emissions and natural emissions, Al is higher in summer and lower in winter, Fe is higher in winter lower in autumn. Cu, Cr, Cd, Ni, Mn, Sr, V, As, and Ba concentrations have lower content in four seasons, which indicates that emissions sources of these elements are more stable.

scholarly journals Determining the Role of Acidity, Fate and Formation of IEPOX-Derived SOA in CMAQ

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 707
Author(s):  
Petros Vasilakos ◽  
Yongtao Hu ◽  
Armistead Russell ◽  
Athanasios Nenes
Keyword(s):  
Significant Influence ◽  
Organic Aerosol ◽  
Liquid Water Content ◽  
Anthropogenic Emissions ◽  
So2 Emissions ◽  
Aerosol Acidity ◽  
A Value ◽  
Future Emission ◽  
The Impact

Formation of aerosol from biogenic hydrocarbons relies heavily on anthropogenic emissions since they control the availability of species such as sulfate and nitrate, and through them, aerosol acidity (pH). To elucidate the role that acidity and emissions play in regulating Secondary Organic Aerosol (SOA), we utilize the 2013 Southern Oxidant and Aerosol Study (SOAS) dataset to enhance the extensive mechanism of isoprene epoxydiol (IEPOX)-mediated SOA formation implemented in the Community Multiscale Air Quality (CMAQ) model (Pye et al., 2013), which was then used to investigate the impact of potential future emission controls on IEPOX OA. We found that the Henry’s law coefficient for IEPOX was the most impactful parameter that controls aqueous isoprene OA products, and a value of 1.9 × 107 M atm−1 provides the best agreement with measurements. Non-volatile cations (NVCs) were found in higher-than-expected quantities in CMAQ and exerted a significant influence on IEPOX OA by reducing its production by as much as 30% when present. Consistent with previous literature, a strong correlation of isoprene OA with sulfate, and little correlation with acidity or liquid water content, was found. Future reductions in SO2 emissions are found to not affect this correlation and generally act to increase the sensitivity of IEPOX OA to sulfate, even in extreme cases.

Further Studies upon Chemical Factors Affecting the Breeding of Anopheles in Trinidad

1934 ◽  
Vol 25 (4) ◽  
pp. 491-494 ◽  
Author(s):  
P. A. Buxton
Keyword(s):  
Analytical Study ◽  
Chemical Constituents ◽  
Physical Factors ◽  
Factors Affecting ◽  
Early Stages ◽  
Freshwater Biology ◽  
Chemical Technique ◽  
Chemical Factors ◽  
Physical And Chemical

During the last decade, entomologists have made progress in understanding the environment in which certain insects live; in particular, we begin to understand the effect of certain physical and chemical factors, which make up a part of the environment. With this gain in knowledge, it is sometimes possible to forecast outbreaks of insects and of diseases conveyed by them, and one can sometimes say that a particular alteration of the environment will result in loss or gain. But so far as mosquitos are concerned, one must admit that though much work has been devoted to the analytical study of the water in which the early stages are passed, the results are disappointing. A consideration of the published work suggests several reasons for this. Investigation into the ecology of the mosquito has had a vogue, and much of it has been done by workers who were isolated and whose knowledge of chemical technique and freshwater biology was limited. Apart from that, the inherent difficulties are great, for the worker must hunt for the limiting chemical and physical factors among a host of others which are doubtless unimportant, and there are few clues to indicate which of the chemical constituents of the water affects the mosquito. The data are therefore voluminous and it is difficult to reduce them to order and present them so that they can be readily understood.

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