Microbial communities,sulfur isotope of sulfides(δ^(34)S_(AVS)and δ^(34)S_(CRS)),and sulfur and oxygen isotopes of sulfate(δ^(34)S_(SO_(4))and δ^(18)O_(SO_(4)))in sediments were analyzed to reveal the biogeochemic...Microbial communities,sulfur isotope of sulfides(δ^(34)S_(AVS)and δ^(34)S_(CRS)),and sulfur and oxygen isotopes of sulfate(δ^(34)S_(SO_(4))and δ^(18)O_(SO_(4)))in sediments were analyzed to reveal the biogeochemical transformations of sulfur in a seabird-affected lake Y2 and a se abird-free YO from Fildes Peninsula,Antarctic Peninsula.The microbial communities in Y2 were mainly associated with penguin activities,while those in YO were limited by nutrients.The much enriched δ^(34)S_(SO_(4))recorded at depth of 30,41,and 52 cm in Y2indicates very strong sulfate reduction therein.The sulfur-degrading bacteria Pseudomonas in 0-23 cm of Y2 was 3.5 time s as abundant as that of sulfur oxidizing bacteria(SOB),indicating remarkable remineralization of organic sulfur.The abundant SOB and ^(34)S-depleted sulfate indicate considerable sulfur oxidation in 34-56-cm layer in Y2.In YO sediments,the highest abundance of Desulfotalea and the most enriched δ^(34)S_(SO_(4))(35.2‰)and δ^(34)S_(CRS)(2.5‰)indicate the strongest sulfate reduction in 28-cm layer.High abundance of Pseudomonas indicates active remineralization of organic sulfur in 3-5-cm layer in YO.The medium δ^(34)S_(SO_(4))and considerable abundance of SOB and sulfate-reducing bacteria(SRB)indicate concurrence of sulfur oxidation and sulfate reduction in other layers in YO.Therefore,a high level of organic matter input from penguin populations supported the diverse microbial community and transformations of sulfur in aquatic ecosystems in Antarctica.展开更多
Short-lived climatically important atmospheric aerosols and trace gases such as ozone play major roles in global and regional climates,the chemistry of the atmosphere,and the biogeochemical cycling of nutrients such a...Short-lived climatically important atmospheric aerosols and trace gases such as ozone play major roles in global and regional climates,the chemistry of the atmosphere,and the biogeochemical cycling of nutrients such as phosphorus.Because of the large spatial and temporal variations in their characteristics,it is of the utmost importance to have展开更多
Despite millions of seafarers and passengers staying on ships each year, few studies have been conducted on the indoor air quality inside ship hulls. In this study, we investigated the levels and size distribution of ...Despite millions of seafarers and passengers staying on ships each year, few studies have been conducted on the indoor air quality inside ship hulls. In this study, we investigated the levels and size distribution of indoor particulate matter during two cruises of the research vessel “Xuelong” from Shanghai to Antarctica. The results showed that the particle size less than 2.5 μm(PM_(2.5)), and particle size less than 10 μm(PM_(10)) concentrations in different rooms of the ship widely varied. We observed high particulate matter(PM) levels in some of the rooms. The mass concentration distribution was dominated by 1–4 μm particles, which may have been caused by the hygroscopic growth of fine particles. The dominant factors influencing PM concentrations were indoor temperature, relative humidity, and human activity. We quantified contributions of these factors to the levels of indoor particles using a generalized additive model. In clean rooms, the levels of indoor particles were controlled by temperature and relative humidity, whereas in polluted rooms, the levels of indoor particles were mainly influenced by temperature and human activity, which implied that controlling temperature and human activity would efficiently reduce the levels of indoor particles.展开更多
Beijing–Tianjin–Hebei area is suffering from atmospheric pollution from a long time. The understanding of the air pollution mechanism is of great importance for officials to design strategies for the environmental g...Beijing–Tianjin–Hebei area is suffering from atmospheric pollution from a long time. The understanding of the air pollution mechanism is of great importance for officials to design strategies for the environmental governance. Mixing layer height(MLH) is a key factor influencing the diffusion of air pollutants. It plays an important role on the evolution of heavy pollution events. Light detection and ranging(lidar), is an effective remote-sensing tool, which can retrieve high spatial and temporal evolution process within mixing layer(ML), especially the variation of MLH. There are many methods to retrieve MLH, but each method has its own applicable limitations. The Mie-lidar data in Beijing was firstly used to compare three different algorithms which are widely used under different pollution levels.We find that the multi-layer structure near surface may cause errors in the detection of mixing layer. The MLH retrieved based on image edge detection was better than another two methods especially under heavy polluted episode. Then we applied this method to investigate the evolution of the mixing layer height during a pollution episode in December2016. MLH at Gucheng county showed the positive correlation with the concentration of particulate matters during the start of this pollution episode. The elevated pollution level in Gucheng was not associated with MLH's decrease, and the significantly increased particulate matters raised the boundary layer, which trapped the pollutants near the surface.展开更多
We present mobile vehicle lidar observations in Tianjin, China during the spring, summer, and winter of 2016. Mobile observations were carried out along the city border road of Tianjin to obtain the vertical distribut...We present mobile vehicle lidar observations in Tianjin, China during the spring, summer, and winter of 2016. Mobile observations were carried out along the city border road of Tianjin to obtain the vertical distribution characteristics of PM_(2.5). Hygroscopic growth was not considered since relative humidity was less than 60% during the observation experiments. PM_(2.5) profile was obtained with the linear regression equation between the particle extinction coefficient and PM_(2.5) mass concentration. In spring, the vertical distribution of PM_(2.5) exhibited a hierarchical structure. In addition to a layer of particles that gathered near the ground, a portion of particles floated at 0.6–2.5-km height. In summer and winter, the fine particles basically gathered below 1 km near the ground. In spring and summer, the concentration of fine particles in the south was higher than that in the north because of the influence of south wind. In winter, the distribution of fine particles was opposite to that measured during spring and summer. High concentrations of PM_(2.5) were observed in the rural areas of North Tianjin with a maximum of 350 μg m–3 on 13 December2016. It is shown that industrial and ship emissions in spring and summer and coal combustion in winter were the major sources of fine particles that polluted Tianjin. The results provide insights into the mechanisms of haze formation and the effects of meteorological conditions during haze–fog pollution episodes in the Tianjin area.展开更多
We investigated the acidity and concentrations of water-soluble ions in PM_(2.5) aerosol samples collected from an urban site in Beijing and a rural site in Gucheng, Hebei Province from November 2016 to January 2017 t...We investigated the acidity and concentrations of water-soluble ions in PM_(2.5) aerosol samples collected from an urban site in Beijing and a rural site in Gucheng, Hebei Province from November 2016 to January 2017 to gain an insight into the formation of secondary inorganic species. The average SO_4^(2–), NO_3~–, and NH_4^+ concentrations were 8.3,12.5, and 14.1 μg m^(–3), respectively, at the urban site and 14.0, 14.2, and 24.2 μg m^(–3), respectively, at the rural site.The nitrogen and sulfur oxidation ratios in urban Beijing were correlated with relative humidity(with correlation coefficient r = 0.79 and 0.67, respectively) and the aerosol loadings. Based on a parameterization model, we found that the rate constant of the heterogeneous reactions for SO_2 on polluted days was about 10 times higher than that on clear days, suggesting that the heterogeneous reactions in the aerosol water played an essential role in haze events.The ISORROPIA II model was used to predict the aerosol pH, which had a mean(range) of 5.0(4.9–5.2) and 5.3(4.6–6.3) at the urban and rural site, respectively. Under the conditions with this predicted pH value, oxidation by dissolved NO_2 and the hydrolysis of N_2O_5 may be the major heterogeneous reactions forming SO_4^(2–) and NO_3~– in haze.We also analyzed the sensitivity of the aerosol p H to changes in the concentrations of SO_4^(2–), NO_3~–, and NH_4^+ under haze conditions. The aerosol p H was more sensitive to the SO_4^(2–) and NH_4^+ concentrations with opposing trends, than to the NO_3~– concentrations. The sensitivity of the p H was relatively weak overall, which was attributed to the buffering effect of NH_3 partitioning.展开更多
New particle formation(NPF)events are an increasingly interesting topic in air quality and climate science.In this study,the particle number size distributions,and the frequency of NPF events over Hefei were investiga...New particle formation(NPF)events are an increasingly interesting topic in air quality and climate science.In this study,the particle number size distributions,and the frequency of NPF events over Hefei were investigated from November 2018 to February 2019.The proportions of the nucleation mode,Aitken mode,and accumulation mode were 24.59%,53.10%,and 22.30%,respectively,which indicates the presence of abundant ultrafine particles in Hefei.Forty-six NPF events occurred during the observation days,accounting for 41.82%of the entire observation period.Moreover,the favorable meteorological conditions,potential precursor gases,and PM_(2.5)range of the NPF events were analyzed.Compared to non-NPF days,the NPF events preferentially occurred on days with lower relative humidity,higher wind speeds,and higher temperatures.When the PM_(2.5) was 15–20,70–80,and105–115μg/m^(3),the frequency of the NPF events was higher.Nucleation mode particles were positively related to atmospheric oxidation indicated by ozone when PM_(2.5) ranged from 15 to 20μg/m^(3),and related to gaseous precursors like SO_(2) and NO_(2) when PM_(2.5)was located at 70-80 and 105–115μg/m^(3).On pollution days,NPF events did not directly contribute to the increase in the PM_(2.5) in the daytime,however,NPF events would occur during the night and the growth of particulate matter contributes to the nighttime PM_(2.5) contents.This could lead to pollution that lasted into the next day.These findings are significant to the improvement of our understanding of the effects of aerosols on air quality.展开更多
基金Supported by the National Natural Science Foundation of China(No.41476165)the University Natural Science Research Project of Anhui Province(No.KJ2019A0042)。
文摘Microbial communities,sulfur isotope of sulfides(δ^(34)S_(AVS)and δ^(34)S_(CRS)),and sulfur and oxygen isotopes of sulfate(δ^(34)S_(SO_(4))and δ^(18)O_(SO_(4)))in sediments were analyzed to reveal the biogeochemical transformations of sulfur in a seabird-affected lake Y2 and a se abird-free YO from Fildes Peninsula,Antarctic Peninsula.The microbial communities in Y2 were mainly associated with penguin activities,while those in YO were limited by nutrients.The much enriched δ^(34)S_(SO_(4))recorded at depth of 30,41,and 52 cm in Y2indicates very strong sulfate reduction therein.The sulfur-degrading bacteria Pseudomonas in 0-23 cm of Y2 was 3.5 time s as abundant as that of sulfur oxidizing bacteria(SOB),indicating remarkable remineralization of organic sulfur.The abundant SOB and ^(34)S-depleted sulfate indicate considerable sulfur oxidation in 34-56-cm layer in Y2.In YO sediments,the highest abundance of Desulfotalea and the most enriched δ^(34)S_(SO_(4))(35.2‰)and δ^(34)S_(CRS)(2.5‰)indicate the strongest sulfate reduction in 28-cm layer.High abundance of Pseudomonas indicates active remineralization of organic sulfur in 3-5-cm layer in YO.The medium δ^(34)S_(SO_(4))and considerable abundance of SOB and sulfate-reducing bacteria(SRB)indicate concurrence of sulfur oxidation and sulfate reduction in other layers in YO.Therefore,a high level of organic matter input from penguin populations supported the diverse microbial community and transformations of sulfur in aquatic ecosystems in Antarctica.
文摘Short-lived climatically important atmospheric aerosols and trace gases such as ozone play major roles in global and regional climates,the chemistry of the atmosphere,and the biogeochemical cycling of nutrients such as phosphorus.Because of the large spatial and temporal variations in their characteristics,it is of the utmost importance to have
基金supported by the National Natural Science Foundation of China (Nos. 41941014, 41676173)the Ministry of Natural Resources of the People’s Republic of China (No. IRASCC_(2)020-2022-No.01-01-02E)supported by China Arctic and Antarctic Administration。
文摘Despite millions of seafarers and passengers staying on ships each year, few studies have been conducted on the indoor air quality inside ship hulls. In this study, we investigated the levels and size distribution of indoor particulate matter during two cruises of the research vessel “Xuelong” from Shanghai to Antarctica. The results showed that the particle size less than 2.5 μm(PM_(2.5)), and particle size less than 10 μm(PM_(10)) concentrations in different rooms of the ship widely varied. We observed high particulate matter(PM) levels in some of the rooms. The mass concentration distribution was dominated by 1–4 μm particles, which may have been caused by the hygroscopic growth of fine particles. The dominant factors influencing PM concentrations were indoor temperature, relative humidity, and human activity. We quantified contributions of these factors to the levels of indoor particles using a generalized additive model. In clean rooms, the levels of indoor particles were controlled by temperature and relative humidity, whereas in polluted rooms, the levels of indoor particles were mainly influenced by temperature and human activity, which implied that controlling temperature and human activity would efficiently reduce the levels of indoor particles.
基金supported by grants from National Key Research and Development Program of China (Nos. 2016YFC0203302, 2018YFC0213100, 2018YFC0213104)the National Natural Science Foundation of China (Nos. 41722501, 91544212, 51778596, 41575021)the National High-Resolution Earth Observation Project of China under grant of 05Y20A16-9001-15/17-2
文摘Beijing–Tianjin–Hebei area is suffering from atmospheric pollution from a long time. The understanding of the air pollution mechanism is of great importance for officials to design strategies for the environmental governance. Mixing layer height(MLH) is a key factor influencing the diffusion of air pollutants. It plays an important role on the evolution of heavy pollution events. Light detection and ranging(lidar), is an effective remote-sensing tool, which can retrieve high spatial and temporal evolution process within mixing layer(ML), especially the variation of MLH. There are many methods to retrieve MLH, but each method has its own applicable limitations. The Mie-lidar data in Beijing was firstly used to compare three different algorithms which are widely used under different pollution levels.We find that the multi-layer structure near surface may cause errors in the detection of mixing layer. The MLH retrieved based on image edge detection was better than another two methods especially under heavy polluted episode. Then we applied this method to investigate the evolution of the mixing layer height during a pollution episode in December2016. MLH at Gucheng county showed the positive correlation with the concentration of particulate matters during the start of this pollution episode. The elevated pollution level in Gucheng was not associated with MLH's decrease, and the significantly increased particulate matters raised the boundary layer, which trapped the pollutants near the surface.
基金Supported by the National Key Project of Ministry of Science and Technology of China(2016YFC0203302)National 863 Program for High Technology Research and Development(2014AA06A512)+2 种基金National(Key)Basic Research and Development(973)Program of China(2014CB447900)National Natural Science Foundation of China(91544232,41305126,and 41605020)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB05040300)
文摘We present mobile vehicle lidar observations in Tianjin, China during the spring, summer, and winter of 2016. Mobile observations were carried out along the city border road of Tianjin to obtain the vertical distribution characteristics of PM_(2.5). Hygroscopic growth was not considered since relative humidity was less than 60% during the observation experiments. PM_(2.5) profile was obtained with the linear regression equation between the particle extinction coefficient and PM_(2.5) mass concentration. In spring, the vertical distribution of PM_(2.5) exhibited a hierarchical structure. In addition to a layer of particles that gathered near the ground, a portion of particles floated at 0.6–2.5-km height. In summer and winter, the fine particles basically gathered below 1 km near the ground. In spring and summer, the concentration of fine particles in the south was higher than that in the north because of the influence of south wind. In winter, the distribution of fine particles was opposite to that measured during spring and summer. High concentrations of PM_(2.5) were observed in the rural areas of North Tianjin with a maximum of 350 μg m–3 on 13 December2016. It is shown that industrial and ship emissions in spring and summer and coal combustion in winter were the major sources of fine particles that polluted Tianjin. The results provide insights into the mechanisms of haze formation and the effects of meteorological conditions during haze–fog pollution episodes in the Tianjin area.
基金Supported by the National Key Project of Ministry of Science and Technology of China(2016YFC0203302)National Natural Science Foundation of China(91544103)
文摘We investigated the acidity and concentrations of water-soluble ions in PM_(2.5) aerosol samples collected from an urban site in Beijing and a rural site in Gucheng, Hebei Province from November 2016 to January 2017 to gain an insight into the formation of secondary inorganic species. The average SO_4^(2–), NO_3~–, and NH_4^+ concentrations were 8.3,12.5, and 14.1 μg m^(–3), respectively, at the urban site and 14.0, 14.2, and 24.2 μg m^(–3), respectively, at the rural site.The nitrogen and sulfur oxidation ratios in urban Beijing were correlated with relative humidity(with correlation coefficient r = 0.79 and 0.67, respectively) and the aerosol loadings. Based on a parameterization model, we found that the rate constant of the heterogeneous reactions for SO_2 on polluted days was about 10 times higher than that on clear days, suggesting that the heterogeneous reactions in the aerosol water played an essential role in haze events.The ISORROPIA II model was used to predict the aerosol pH, which had a mean(range) of 5.0(4.9–5.2) and 5.3(4.6–6.3) at the urban and rural site, respectively. Under the conditions with this predicted pH value, oxidation by dissolved NO_2 and the hydrolysis of N_2O_5 may be the major heterogeneous reactions forming SO_4^(2–) and NO_3~– in haze.We also analyzed the sensitivity of the aerosol p H to changes in the concentrations of SO_4^(2–), NO_3~–, and NH_4^+ under haze conditions. The aerosol p H was more sensitive to the SO_4^(2–) and NH_4^+ concentrations with opposing trends, than to the NO_3~– concentrations. The sensitivity of the p H was relatively weak overall, which was attributed to the buffering effect of NH_3 partitioning.
基金supported by grants from the National Key Research and Development Program of China(Nos.2017YFC0210002,2018YFC0213104,2016YFC0203302 and 2017YFC0212800)the National Natural Science Foundation of China(Nos.41722501,51778596,and 41977184)+5 种基金the Anhui Science and Technology Major Project(No.18030801111)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23020301)the National Key Project for Causes and Control of Heavy Air Pollution(Nos.DQGG0102 and DQGG0205)the Natural Science Foundation of Anhui Province(No.1908085QD170)the Key Research and Development Project of Anhui Province(No.202004i07020002)the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment,CAS(No.CERAE202004)。
文摘New particle formation(NPF)events are an increasingly interesting topic in air quality and climate science.In this study,the particle number size distributions,and the frequency of NPF events over Hefei were investigated from November 2018 to February 2019.The proportions of the nucleation mode,Aitken mode,and accumulation mode were 24.59%,53.10%,and 22.30%,respectively,which indicates the presence of abundant ultrafine particles in Hefei.Forty-six NPF events occurred during the observation days,accounting for 41.82%of the entire observation period.Moreover,the favorable meteorological conditions,potential precursor gases,and PM_(2.5)range of the NPF events were analyzed.Compared to non-NPF days,the NPF events preferentially occurred on days with lower relative humidity,higher wind speeds,and higher temperatures.When the PM_(2.5) was 15–20,70–80,and105–115μg/m^(3),the frequency of the NPF events was higher.Nucleation mode particles were positively related to atmospheric oxidation indicated by ozone when PM_(2.5) ranged from 15 to 20μg/m^(3),and related to gaseous precursors like SO_(2) and NO_(2) when PM_(2.5)was located at 70-80 and 105–115μg/m^(3).On pollution days,NPF events did not directly contribute to the increase in the PM_(2.5) in the daytime,however,NPF events would occur during the night and the growth of particulate matter contributes to the nighttime PM_(2.5) contents.This could lead to pollution that lasted into the next day.These findings are significant to the improvement of our understanding of the effects of aerosols on air quality.
