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Author

Junwen Liu

Bio: Junwen Liu is an academic researcher from Jinan University. The author has contributed to research in topics: Medicine & Environmental science. The author has an hindex of 16, co-authored 37 publications receiving 788 citations. Previous affiliations of Junwen Liu include Chinese Academy of Sciences & Oeschger Centre for Climate Change Research.

Papers published on a yearly basis

Papers
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Journal ArticleDOI
TL;DR: Investigation of the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon ((14)C) and biomass burning/secondary organic aerosol (SOA) tracers during winter in Guangzhou, China found that haze episodes were formed either abruptly by local emissions or through the accumulation of particles transported from other areas.
Abstract: We conducted a source apportionment and investigated the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon (14C) and biomass burning/secondary organic aero...

129 citations

Journal ArticleDOI
TL;DR: In this paper, the presence of butyltin compounds was investigated for the first time in selected lakes, rivers and coastal environments of China using headspace solid phase micro-extraction after hydride generation with sodium tetrahydroborate (NaBH4).

97 citations

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TL;DR: The need of spatio-temporal monitoring of OCPs at local and regional scale to assess and remediate the future adverse implications of organochlorine pesticides is emphasized.

79 citations

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TL;DR: In this paper, the USEPA priority polycyclic aromatic hydrocarbons (PAHs) and benzo[e]pyrene were detected in the air samples collected at two suburban sites in Lhasa city.

68 citations

Journal ArticleDOI
TL;DR: The contribution of atmospheric deposition to PAH concentrations in the sediments was estimated to be 30% to 40% in the coastal regions of South China as discussed by the authors, and the annual mean washout ratio, defined as the ratio between the particle-associated concentrations of PAHs in precipitations and aerosols, was 3.4 × 105 in this study.

61 citations


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01 Dec 2006
TL;DR: This paper showed that reactive anthropogenic VOCs (AVOCs) produce much larger amounts of SOA than these models predict, even shortly after sunrise, and a significant fraction of the excess SOA is formed from first-generation AVOC oxidation products.
Abstract: [1] The atmospheric chemistry of volatile organic compounds (VOCs) in urban areas results in the formation of ‘photochemical smog’, including secondary organic aerosol (SOA). State-of-the-art SOA models parameterize the results of simulation chamber experiments that bracket the conditions found in the polluted urban atmosphere. Here we show that in the real urban atmosphere reactive anthropogenic VOCs (AVOCs) produce much larger amounts of SOA than these models predict, even shortly after sunrise. Contrary to current belief, a significant fraction of the excess SOA is formed from first-generation AVOC oxidation products. Global models deem AVOCs a very minor contributor to SOA compared to biogenic VOCs (BVOCs). If our results are extrapolated to other urban areas, AVOCs could be responsible for additional 3–25 Tg yr−1 SOA production globally, and cause up to −0.1 W m−2 additional top-of-the-atmosphere radiative cooling.

947 citations

Journal ArticleDOI
TL;DR: It is essential to discuss the agricultural development process; the historical perspective, types and specific uses of pesticides; and pesticide behavior, its contamination, and adverse effects on the natural environment to provide the scientific information necessary for pesticide application and management in the future.
Abstract: Pesticides are indispensable in agricultural production. They have been used by farmers to control weeds and insects, and their remarkable increases in agricultural products have been reported. The increase in the world's population in the 20th century could not have been possible without a parallel increase in food production. About one-third of agricultural products are produced depending on the application of pesticides. Without the use of pesticides, there would be a 78% loss of fruit production, a 54% loss of vegetable production, and a 32% loss of cereal production. Therefore, pesticides play a critical role in reducing diseases and increasing crop yields worldwide. Thus, it is essential to discuss the agricultural development process; the historical perspective, types and specific uses of pesticides; and pesticide behavior, its contamination, and adverse effects on the natural environment. The review study indicates that agricultural development has a long history in many places around the world. The history of pesticide use can be divided into three periods of time. Pesticides are classified by different classification terms such as chemical classes, functional groups, modes of action, and toxicity. Pesticides are used to kill pests and control weeds using chemical ingredients; hence, they can also be toxic to other organisms, including birds, fish, beneficial insects, and non-target plants, as well as air, water, soil, and crops. Moreover, pesticide contamination moves away from the target plants, resulting in environmental pollution. Such chemical residues impact human health through environmental and food contamination. In addition, climate change-related factors also impact on pesticide application and result in increased pesticide usage and pesticide pollution. Therefore, this review will provide the scientific information necessary for pesticide application and management in the future.

451 citations

01 Dec 2007
TL;DR: In this article, the authors examined absorption spectra of primary organic carbon (OC) emitted from solid fuel pyrolysis and found that more than 92% was extractable by methanol or acetone compared with 73% for water and 52% for hexane.
Abstract: Abstract. Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While black carbon (BC) is highly absorbing, some organic carbon (OC) also has significant absorption, especially at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to positive direct aerosol radiative forcing. Quantification of that absorption is necessary so that radiative-transfer models can evaluate the net radiative effect of OC. In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble OC contributes to light absorption at both ultraviolet and visible wavelengths. However, a larger portion of the absorption comes from OC that is extractable only by methanol. Absorption spectra of water-soluble OC are similar to literature reports. We compare spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating OC with higher absorption; changing wood temperature from a devolatilizing state of 210 °C to a near-flaming state of 360 °C causes about a factor of four increase in mass-normalized absorption at visible wavelengths. A clear-sky radiative transfer model suggests that, despite the absorption, both high-temperature and low-temperature OC result in negative top-of-atmosphere radiative forcing over a surface with an albedo of 0.19 and positive radiative forcing over bright surfaces. Unless absorption by real ambient aerosol is higher than that measured here, it probably affects global average clear-sky forcing very little, but could be important in energy balances over bright surfaces.

446 citations

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TL;DR: It can be concluded that India is one of the major contributors of global persistent organic pesticide distribution and its impact on neighboring countries and regions is highlighted.

441 citations

Journal ArticleDOI
TL;DR: The data preliminarily reveal the state of contamination in this region and give insight into the fate of POPs in this sub-tropical area.

403 citations