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Bioaerosols play significant roles in causing health and climate effects. Sugar compounds in air have been widely used to trace the source of bioaerosols. However, knowledge about the association of sugar molecules and the microbial community at taxonomic levels in atmospheric aerosols remains limited. Here, microbial community compositions and sugar molecules in total suspended particles collected from a typical rural site, Gucheng, in the North China Plain were investigated by gas chromatography–mass spectrometry and high-throughput gene sequencing, respectively. Results show that fungal community structure exhibited distinct diurnal variation with largely enhanced contribution of Basidiomycota at night, while bacterial community structure showed no obvious difference between daytime and night. SourceTracker analysis revealed that fungi and bacteria were mainly from plant leaves and unresolved sources (presumably human-related emissions and/or long-distance transport). All the detected anhydrosugars and sugar alcohols and trehalose showed diurnal variations with lower concentrations in the daytime and higher concentrations at night, which may be affected by enhanced fungal emissions at night, while primary sugars (except trehalose) showed an opposite trend. Mantel's test showed that more sugar compounds exhibited significant associations with fungal community structure than bacterial community structure. Co-occurrence analysis revealed the strong associations between sugar compounds and a few saprophytic fungal genera with low relative abundances, e.g., Hannaella, Lectera, Peniophora, Hydnophlebia, Sporobolomyces and Cyphellophora. This study suggests that the entire fungal community, rather than specific fungal taxa, likely greatly contributes to sugar compounds in rural aerosols, while the contribution of bacteria is limited. [ABSTRACT FROM AUTHOR]

Brown carbon (BrC) aerosols exert vital impacts on climate change and atmospheric photochemistry due to their light absorption in the wavelength range from near-ultraviolet (UV) to visible light. However, the optical properties and formation mechanisms of ambient BrC remain poorly understood, limiting the estimation of their radiative forcing. In the present study, fine particles (PM 2.5) were collected during 2016–2017 on a day/night basis over urban Tianjin, a megacity in northern China. Light absorption and fluorescence properties of water extracts of PM 2.5 were investigated to obtain seasonal and diurnal patterns of atmospheric water-soluble BrC. There were obvious seasonal, but no evident diurnal, variations in the light absorption properties of BrC. In winter, BrC showed much stronger light-absorbing ability, with a mass absorption efficiency at 365 nm (MAE 365) in winter (1.54±0.33 m 2 gC -1) that was 1.8 times larger than MAE 365 in summer (0.84±0.22 m 2 gC -1). Direct radiative effects by BrC absorption relative to black carbon in the UV range were 54.3±16.9 % and 44.6±13.9 % in winter and summer, respectively. In addition, five fluorescent components in BrC, including three humic-like fluorophores and two protein-like fluorophores were identified with excitation–emission matrix fluorescence spectrometry and parallel factor (PARAFAC) analysis. The less oxygenated components contributed more to winter and nighttime samples, while more oxygenated components increased in summer and daytime samples. The higher humification index (HIX), together with lower biological index (BIX) and fluorescence index (FI), suggests that the chemical compositions of BrC were associated with a high aromaticity degree in summer and daytime due to photobleaching. Fluorescent properties indicate that wintertime BrC were predominantly affected by primary emissions and fresh secondary organic aerosol (SOA), while summer ones were more influenced by aging processes. Results of source apportionments using organic molecular compositions of the same set of aerosols reveal that fossil fuel combustion and aging processes, primary bioaerosol emission, biomass burning, and biogenic and anthropogenic SOA formation were the main sources of BrC. Biomass burning contributed much more to BrC in winter and at nighttime, while biogenic SOA contributed more in summer and during the daytime. In particular, our study highlights that primary bioaerosol emission is an important source of BrC in urban Tianjin in summer. [ABSTRACT FROM AUTHOR]

In order to better understand the molecular composition and sources of organic aerosols in Tianjin, a coastal megacity in North China, ambient fine aerosol (PM 2.5) samples were collected on a day/night basis from November to December 2016 and from May to June 2017. The organic molecular composition of PM 2.5 components, including aliphatic lipids (n -alkanes, fatty acids, and fatty alcohols), sugar compounds, and photooxidation products from isoprene, monoterpene, β -caryophyllene, naphthalene, and toluene, was analysed using gas chromatography–mass spectrometry. Fatty acids, fatty alcohols, and saccharides were identified as the most abundant organic compound classes among all of the tracers detected in this study during both seasons. High concentrations of most organics at night in winter may be attributed to intensive residential activities such as house heating as well as the low nocturnal boundary layer height. Based on tracer methods, the contributions of the sum of primary and secondary organic carbon (POC and SOC respectively) to aerosol organic carbon (OC) were 24.8 % (daytime) and 27.6 % (night-time) in winter and 38.9 % (daytime) and 32.5 % (night-time) in summer. In detail, POC derived from fungal spores, plant debris, and biomass burning accounted for 2.78 %–31.6 % (12.4 %; please note that values displayed in parentheses in the following are average values) of OC during the daytime and 4.72 %–45.9 % (16.3 %) at night in winter, and 1.28 %–9.89 % (5.24 %) during the daytime and 2.08 %–47.2 % (10.6 %) at night in summer. Biomass-burning-derived OC was the predominant source of POC in this study, especially at night (16.0±6.88 % in winter and 9.62±8.73 % in summer). Biogenic SOC from isoprene, α - /β -pinene, and β -caryophyllene exhibited obvious seasonal and diurnal patterns, contributing 2.23±1.27 % (2.30±1.35 % during the daytime and 2.18±1.19 % at night) and 8.60±4.02 % (8.98±3.67 % and 8.21±4.39 %) to OC in winter and summer respectively. Isoprene and α - /β -pinene SOC were obviously elevated in summer, especially during the daytime, mainly due to strong photooxidation. Anthropogenic SOC from toluene and naphthalene oxidation showed higher contributions to OC in summer (21.0±18.5 %) than in winter (9.58±3.68 %). In summer, toluene SOC was the dominant contributor to aerosol OC, and biomass burning OC also accounted for a high contribution to OC, especially at night-time; this indicates that land/sea breezes also play an important role in the aerosol chemistry of the coastal city of Tianjin in North China. [ABSTRACT FROM AUTHOR]

Tropical seabirds play a key role in coral island ecosystems, but there are still many uncertainties regarding their paleoecology. Seabird paleoecology was investigated on Nandao Island, Xisha Islands, South China Sea, from sub-fossil remains spanning the past 800 years. Ornithogenic sediments were collected beneath seabird-inhabited shrubs where a large number of seabird/fish sub-fossils were recovered. We used reflectance spectroscopy to show that seabird population size was overall higher during the Little Ice Age (LIA) compared to periods before and after this event. Nonetheless, the number of seabirds also fluctuated during the LIA. Seabird populations on Nandao reached their highest points at 1480–1550 and 1650–1800 CE, respectively, but the population remained low from 1550 to 1650 CE. A large migration of seabirds from Nandao Island to the adjacent Beidao Island, where the population size surged at that time, is hypothesized to explain the corresponding decrease in the seabirds at Nandao. Stable isotope (δ 15 N and δ 13 C) analyses also suggest a change in foraging behavior by seabirds at Nandao during the period 1550–1650 CE. Seabirds at low population size foraged near the island and preyed upon smaller flying fish as inferred from low δ 15 N and high δ 13 C values in fish scales, but fed upon larger flying fish farther from the island during times of high population. This shift in foraging behavior is in accordance with predictions for Ashmole's Halo in that islands with high densities of birds will cause a depletion of resources near the colonies and force more distant foraging away from the colony. [ABSTRACT FROM AUTHOR]

The Tongling district is one of the most important non-ferrous metal producers in China. The origin of Cu-Au deposits in the region is closely related to Late Mesozoic intermediate intrusions, which are mainly high-K calc-alkaline and shoshonitic series. Geochemical characteristics indicate that these granitic rocks are mixtures of more than two compositional end-members, i.e. mantle-derived melts and crust components incorporated through assimilation. Three important magmatic intrusions related to the Cu-Au deposits in the Tongling region - the Jiguanshi quartz monzodiorite, the Xishizishan quartz diorite and the Miaojia diorite porphyry - were selected for this study. Zircon U-Pb dating by LA ICP-MS yielded two groups of ages (∼130-132 and 138-140 Ma) for these intrusions. Pyrite Re-Os age for the Xinqiao Cu-Fe-S deposit in the Tongling region is 126±11 Ma. Trace elements of zircon grains show that the earlier Cu-Au mineralization event was associated with adakitic rocks characterized by high positive Ce anomalies, produced at an elevated oxygen fugacity range. In contrast, later iron-sulphur mineralization was closely related to low positive Ce anomalies, reflecting low oxygen fugacities. Considering that Pacific lithospheric subduction was the dominant factor that controlled major tectonic evolution in eastern China during the Early Cretaceous, the geochemical characteristics of these coeval ore-forming intermediate intrusive rocks in the Tongling district were likely the result of Pacific plate underflow. [ABSTRACT FROM AUTHOR]

Lipids are important biogenic markers to indicate the sources and chemical process of aerosol particles in the atmosphere. To better understand the influences of biogenic and anthropogenic sources on forest aerosols, total suspended particles (TSP) were collected at Mt. Changbai, Shennongjia, and Xishuangbanna that are located at different climatic zones in northeastern, central and southwestern China. n- Alkanes, fatty acids and n- alcohols were detected in the forest aerosols based on gas chromatography-mass spectrometry. The total concentrations of aliphatic compounds ranged from 15.3 ng m−3 to 566 ng m−3, and fatty acids were the most abundant (44–95%) followed by n- alkanes and n- alcohols. Low molecular weight- (LFAs) and unsaturated fatty acids (UnFAs) showed diurnal variation with higher concentrations during the nighttime in summer, indicating the potential impact from microbial activities on forest aerosols. The differences of oleic acid (C 18:1) and linoleic acid (C 18:2) concentrations between daytime and nighttime increased at lower latitude, indicating more intense photochemical degradation occurred at lower latitude regions. High levels of n- alkanes during daytime in summer with higher values of carbon preference indexes, combining the strong odd carbon number predominance with a maximum at C 27 or C 29 , implied the high contributions of biogenic sources, e.g., higher plant waxes. In contrast, higher concentrations of low molecular weight n- alkanes were detected in winter forest aerosols. Levoglucosan showed a positive correlation (R2 > 0.57) with high- and low molecular weight aliphatic compounds in Mt. Changbai, but such a correlation was not observed in Shennongjia and Xishuangbanna. These results suggest the significant influence of biomass burning in Mt. Changbai, and fossil fuel combustion might be another important anthropogenic source of forest aerosols. This study adds useful information to the current understanding of forest organic aerosols at different geographical locations in China. [Display omitted] • Seasonal differences in impact of biogenic/anthropogenic sources on forest aerosols. • The photodegradation of unsaturated fatty acids was more severe in lower latitudes. • Both biomass burning and fossil fuel combustion contributed to the Mt. Changbai aerosols. • Different patterns of lipids in forest aerosols at different locations in China. [ABSTRACT FROM AUTHOR]

Low molecular weight organic compounds are ubiquitous in the atmosphere. However, knowledge on their concentrations and molecular distribution in fresh snow remains limited. Here, twelve fresh snow samples collected at eight sites in China were investigated for dicarboxylic acids and related compounds (DCRCs) including oxocarboxylic acids and α-dicarbonyls. Dissolved organic carbon (DOC) concentrations in the snow samples ranged from 0.99 to 14.6 mg C L−1. Concentrations of total dicarboxylic acids were from 225 to 1970 μg L−1 (av. 650 μg L−1), while oxoacids (28.3–173, av. 68.1 μg L−1) and dicarbonyls (12.6–69.2, av. 31.3 μg L−1) were less abundant, accounting for 4.6–8.5% (6.2%), 0.45–1.4% (0.73%), and 0.12–0.88% (0.46%) of DOC, respectively. Molecular patterns of dicarboxylic acids are characterized by a predominance of oxalic acid (C 2) (95.0–1030, av. 310 μg L−1), followed by phthalic (Ph) (9.69–244, av. 69.9 μg L−1) or succinic (C 4) (23.8–163, av. 63.7 μg L−1) acid. Higher concentrations of Ph in snow from Beijing and Tianjin than other urban and rural regions suggest significant emissions from vehicular exhausts and other fossil fuel combustion sources in megacities. C 2 constituted 40–54% of total diacids, corresponding to 1.5–2.6% of snow DOC. The total measured DCRCs represent 5.5–10% of snow DOC, which suggests that there are large amounts of unknown organics requiring further investigations. The spatial distributions of diacids exhibited higher loadings in megacities than rural and island sites. Molecular distributions of diacids indicated that the photochemical modification was restrained under the weak solar radiation during the snow events, while anthropogenic primary sources had a more significant influence in megacities than rural areas and islands. • Dicarboxylic acids and related compounds were analyzed in urban, rural and island snow samples. • Total measured dicarboxylic acids and related compounds represent 5.5–10% of snow DOC. • High abundance of phthalic acid in urban snow suggests strong emission from fossil fuel combustion. [ABSTRACT FROM AUTHOR]

The role of agricultural versus vehicle emissions in urban atmospheric ammonia (NH 3 ) remains unclear. The lockdown due to the outbreak of COVID-19 provided an opportunity to assess the role of source emissions on urban NH 3 . Concentrations and δ 15 N of aerosol ammonium (NH 4 + ) were measured before (autumn in 2017) and during the lockdown (summer, autumn, and winter in 2020), and source contributions were quantified using SIAR. Despite the insignificant decrease in NH 4 + concentrations, significantly lower δ 15 N-NH 4 + was found in 2020 (0.6 ± 1.0‰ in PM 2.5 and 1.4 ± 2.1‰ in PM 10 ) than in 2017 (15.2 ± 6.7‰ in PM 2.5 ), which indicates the NH 3 from vehicle emissions has decreased by∼50% during the lockdown while other source emissions are less affected. Moreover, a reversed seasonal pattern of δ 15 N-NH 4 + during the lockdown in Changsha has been revealed compared to previous urban studies, which can be explained by the dominant effect of non-fossil fuel emissions due to the reductions of vehicle emissions during the lockdown period. Our results highlight the effects of lockdown on aerosol δ 15 N-NH 4 + and the importance of vehicle emissions to urban atmospheric NH 3 , providing conclusive evidence that reducing vehicle NH 3 emissions could be an effective strategy to reduce PM 2.5 in Chinese megacities., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Strict emission controls were implemented in Beijing and the surrounding regions in the North China Plain to guarantee good air quality during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. Thus, the APEC period provides a good opportunity to study the sources and formation processes of atmospheric organic aerosol. Here, fine particles (PM 2.5 , particulate matter with a diameter of 2.5 μm or less) collected in urban Beijing before and during the APEC period were analyzed for molecular tracers of primary and secondary organic aerosol (SOA). The primary organic carbon (POC) and secondary organic carbon (SOC) were also reconstructed using a tracer-based method. The concentrations of biogenic SOA tracers ranged from 1.09 to 34.5 ng m -3 (mean 10.3 ± 8.51 ng m -3 ). Monoterpene oxidation products were the largest contributor to biogenic SOA, followed by isoprene- and sesquiterpene-derived SOA. The concentrations of biogenic SOA tracers decreased by 50 % during the APEC, which was largely attributed to the implementation of emission controls by the Chinese government. The increasing mass fractions of biogenic SOA tracers from isoprene and sesquiterpene during the pollution episodes implied that their photooxidation processes contributed to the poor air quality in urban Beijing. The reconstructed biogenic and anthropogenic SOC and POC concentrations were 89.6 ± 96.8 ng m -3 , 570 ± 611 ng m -3 , and 2.49 ± 2.08 μg m -3 , respectively, accounting for 21.9 ± 11.4 % of OC in total. Biomass-burning derived OC was the largest contributor to carbonaceous aerosol over the North China Plain. By comparing the results before and during the APEC, the emission controls effectively mitigated about 34 % of the estimated OC and were more effective at reducing SOC than POC. This suggests that the reduction of the primary organic aerosol loading is harder than SOA over the North China Plain., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Rainwater dissolved organic matter (DOM) plays an important role in the biogeochemical cycle and evolution of organic matter in the land-atmosphere interface. To better understand their sources and molecular composition in the atmosphere, rainwater samples were collected at six different locations along the Yangtze River Basin. Based on the application of a combined approach including excitation-emission matrix (EEM) fluorescence and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), various sources (terrestrial, anthropogenic, and autochthonous sources) of rainwater DOM were revealed. Results show that the derivatives of biogenic volatile organic compounds were widely distributed and contributed to rainwater DOM along the Yangtze River Basin. In the up-river city Batang, rainwater DOM was affected by the long-range atmospheric transport due to the Indian summer monsoon. Lijiang, a city on the southeastern edge of Tibetan plateau, was related to strong local biomass burning. The industrial cities of Panzhihua and Luzhou showed large differences in organic composition due to distinct industrial types. Fuling, a district in Chongqing Municipality, was significantly contributed by aged organics from biomass burning. While rainwater DOM in Shanghai, a coastal megacity, contained a high fraction of sea spray organics. Further, more than 70% of rainwater DOM molecules are associated with 36 typical transformation mechanisms during rainwater-scavenging processes, e.g., oxidation reactions, dealkylation and decarboxylation. Our study demonstrates that local natural and anthropogenic emissions and climatic conditions strongly shaped the chemodiversity and possible precursor-product pairs of rainwater DOM along the Yangtze River Basin, which helps to better understand the biogeochemical cycles of organic matter in a large-scale watershed under the influence of human activities., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Primary biological particles are an important subset of atmospheric aerosols. They have significant impacts on climate change and public health. Tianjin is a coastal megacity in the North China Plain, which is affected by both anthropogenic activities and marine air masses. To study the abundance and dynamic change of bioaerosols in Tianjin, fluorescent biological aerosol particles (FBAPs) in Tianjin were investigated by a wideband integrated bioaerosol sensor (WIBS-4A) in terms of number concentrations and size distributions in summer (11th -25th August 2018). Meanwhile, total suspended particles were collected and analyzed for chemical compounds to identify potential sources of bioaerosols. WIBS data showed that fluorescent biological particles exhibited two peaks at sunrise (~7:00) and in the evening (~20:00), which were probably caused by the enhancement of fungal spores and bacteria. Three rain events occurred during the observation period. Precipitation enhanced the abundance of biological particles, which were likely released from vegetation leaves, resuspended from soil surfaces, and/or carried by raindrops from high altitudes. The abundance of biological particles showed no significant correlation with Na + (r = -0.17), indicating the air masses from marine areas carried limited biological particles compared to those from continental areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Black carbon (BC) plays a vital role in atmospheric environment and climate change. Temporal variations and transport pathways of BC in Xiamen, China with the impacts of synoptic circulation were investigated in 2014 with Aethalometer. Annual mean BC concentration was 4270 ng m -3 . BC exhibited clear diurnal (seasonal) variations, with the maximum of 6182 (4755) ng m -3 at 6:00 (in spring) and minimum of 2847 (3774) ng m -3 at 13:00 (in summer). Conditional probability function analysis indicated that high BC concentrations were associated with northwesterly winds with low wind speed. Air masses originating from the East China Sea and passing along with East China Coast had the highest BC concentrations. Potential source contribution function and concentration weighted trajectory analysis suggested that major sources for BC included the surrounding region, southwestern Fujian and eastern Guangdong to the southwest, Hubei, Hunan and Jiangxi to the northwest, the East China Sea and the South China Sea. Of the nine synoptic circulation patterns, three cyclone-related patterns were associated with low BC concentrations and small biomass burning (BC bb ) contributions. Of the six anticyclone-related patterns, the three cold-high circulations around winter were associated with moderate BC concentrations and large BC bb contributions. The two cold-high patterns in spring and autumn were associated with high BC concentrations and small BC bb contributions, while the warm-high pattern was associated with moderate BC concentration and small BC bb contribution. The findings provide insights into the transport mechanisms of BC with the impacts of synoptic pattern in China., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

To examine whether historical fish bones can record the magnitude of heavy metal pollution, we analyzed up to 700 years old fish bone remains extracted from an ornithogenic sediment profile on Nandao Island, South China Sea. Bulk sediments and subfossil fish bones were analyzed for elemental and mineralogical composition, as well as stable carbon and nitrogen isotopes. The results showed that pre-1850 CE fish bones experienced significant diagenesis, and could not be used to reconstruct historical record of heavy metal pollution. Fish bone diagenesis was mainly attributed to the erosion from guano in sediment profile. In contrast, the fish bones from in post-1850 CE time were well preserved and could provide useful information on historical pollution loads over the past 160 years. Since 1850 CE, relatively high concentrations of heavy metals from anthropogenic sources, especially Zn, were recorded in fish bone subfossils on Nandao Island, South China Sea., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

We analyzed 13 C characteristics in samples of bird bones, feathers, eggshell carbonate and membrane from modern specimens of red-footed booby (Sula sula) as well as fish muscle, scales, and bones from its predominant food source, flying fish (Exocoetus volitans), and muscle from its secondary food source squid (Loligo chinensis), as well as in ancient sub-fossil samples of seabird and flying fish at the Xisha Islands, South China Sea. δ 13 C is tissue-specific in both seabirds and flying fish due to the variance in turn-over among the tissues and differences in the type and content of amino acids across a diverse range of tissues. The δ 13 C discrimination factors also differed significantly among the various tissues between tropical seabirds and their prey. A Suess effect, caused by fossil fuel combustion and the emission of carbon with fewer 13 C isotopes, was observed in the bird and fish tissue from ancient to modern time. Our study provides a multiple variability index for δ 13 C in organisms along a food chain, and verifies that tissue-specific 13 C analysis is essential to identify diet and species and thus is a valuable tool for research on tropical seabird ecology.

We measured total mercury (Hg) and selenium (Se) concentrations as well as stable nitrogen (N) isotopic composition in flyingfish and squid muscle tissues from the eastern Indian Ocean and western South China Sea. The results showed that the mean Hg concentration in squid muscle from the western South China Sea was lower than that in the eastern Indian Ocean. The Hg concentrations in flyingfish and squid muscle samples were positively correlated with organism size (length and weight) and δ 15 N in all the study areas. Furthermore, we found a negative correlation between Se and Hg in molar content of flyingfish and squid muscle from the western South China Sea. The Se:Hg molar ratio was significantly negative correlated with fish weight and δ 15 N, suggesting that the Se:Hg molar ratio decreases with the increase of fish size and trophic level in the food web.

Objective: In order to minimize lead pollution and to protect the identified individuals with high blood lead level from lead contamination, an epidemiological study was carried on children living around the village and township-owned lead industries in Tianying town., Methods: Environmental monitoring: lead levels in air, soil, drinking water and crops were measured. Biological monitoring: 959 children aged 5 - 12 years were selected from villages where the lead smelters located near the residential areas and the battery disassembling was done in some families. The control children (207 pupils) were from other villages without lead exposure. Blood lead, ZnPP and teeth lead were determined. Height, weight and head circle of children and IQ scores were measured., Results: The environment was seriously polluted. The average lead concentrations in air and soils were 8.5 times and 10 times of the MACs (national health standard) respectively. Eighty-five per cent the air samples with lead concentrations higher than the national health standard. Local crops and wheat at farmers' home were also contaminated by lead dust, with. Lead content being 24 times higher than the standard. The mean blood lead and ZnPP levels of children lived in the polluted areas were 496 microgram/L and 9.41 microgram/g Hb respectively. The lead exposure caused adverse effects on children's IQ and physical development., Conclusion: It is necessary to remove and reduce currently active sources of lead pollution in the community and to increase public awareness of potential health effects of lead exposure.