Sensitivity analysis of the Ångstrom exponent for multimodal aerosol size distributions     

Chang H. Jung  Junshik Um  Ji Yi Lee  Yong P. Kim 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(5):625-634

This study characterizes the Ångstrom exponent for polydispersed aerosol size distributions. Under the assumption of a lognormal size distribution, the dependence of Ångstrom exponent on the size distribution and the refractive index with varying real and imaginary parts are determined. Further, the influence of coarse mode particles on the Ångstrom exponent is investigated quantitatively. The results show that the nuclei mode has less influence under the simulation conditions considered in this study. It is also shown that the refractive index is an important factor influencing the Ångstrom exponent. The effect of the coarse mode on the Ångstrom exponent computed with different aerosol number concentrations and as a function of a geometric standard deviation and a geometric mean diameter is tested. It is shown that the coarse mode is crucial for determining the Ångstrom exponent.  相似文献   

Radiative effect of black carbon aerosol on seasonal variation in snow depth in the Northern-Hemisphere     

Woo-Seop Lee  Maeng-Ki Kim 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(2):201-207

In this research, we studied the effects of black carbon (BC) aerosol radiative forcing on seasonal variation in the Northern Hemisphere (NH) using numerical simulations with the NASA finite-volume General Circulation Model (fvGCM) forced with monthly varying three-dimensional aerosol distributions from the Goddard Ozone Chemistry Aerosol Radiation and Transport Model (GOCART). The results show that atmospheric warming due to black carbon aerosols subsequently warm the atmosphere and land surfaces, especially those over Eurasia. As a result, the snow depth in Eurasia was greatly reduced in late winter and spring, and the reduction in snow cover decreased the surface albedo. Our surface energy balance analysis shows that the surface warming due to aerosol absorption causes early snow melting and further increases surface-atmosphere warming through snow/ice albedo feedback. Therefore, BC aerosol forcing may be an important factor affecting the snow/ice albedo in the NH.  相似文献   

Heat flux variations over sea ice observed at the coastal area of the Sejong Station,Antarctica     

Sang-Jong Park  Tae-Jin Choi  Seong-Joong Kim 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(4):443-450

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Learning and climate change     

Brian C. O'Neill  Paul Crutzen  Arnulf Grübler  Minh Ha Duong  Klaus Keller  Charles Kolstad 《Climate Policy》2013,13(5):585-589

Abstract

Learning—i.e. the acquisition of new information that leads to changes in our assessment of uncertainty—plays a prominent role in the international climate policy debate. For example, the view that we should postpone actions until we know more continues to be influential. The latest work on learning and climate change includes new theoretical models, better informed simulations of how learning affects the optimal timing of emissions reductions, analyses of how new information could affect the prospects for reaching and maintaining political agreements and for adapting to climate change, and explorations of how learning could lead us astray rather than closer to the truth. Despite the diversity of this new work, a clear consensus on a central point is that the prospect of learning does not support the postponement of emissions reductions today.  相似文献   

The Use of Stable Sulfur, Oxygen and Hydrogen Isotope Ratios as Geochemical Tracers of Sulfates in the Podwiśniówka Acid Drainage Area (South-Central Poland)   总被引：1，自引：0，他引：1  

Zdzisław M. Migaszewski  Agnieszka Gałuszka  Artur Michalik  Sabina Dołęgowska  Andrzej Migaszewski  Stanisław Hałas  Andrzej Trembaczowski 《Aquatic Geochemistry》2013,19(4):261-280

The paper presents the results of determinations of stable S and O isotopes of dissolved sulfates and O and H stable isotopes of waters from three ponds, that is, Marczakowe Do?y acid pond, Marczakowe Do?y fish pond and Podwi?niówka acid pit pond, located in the Holy Cross Mountains (south-central Poland). The δ³⁴S_V-CDT and δ¹⁸O_V-SMOW of SO₄ ^2? in waters of three ponds (n = 14) varied from ?16.2 to ?9.5 ‰ (mean of ?13.6 ‰) and from ?8.1 to ?3.2 ‰ (mean of ?4.8 ‰), respectively. The mean δ³⁴S–SO₄ ^2? values were closer to those of pyrite (mean of ?25.4 ‰) and efflorescent sulfate salts (mean of ?25.6 ‰), recorded previously in the Podwi?niówka quarry, than to sulfates derived from other anthropogenic or soil and bedrock sources. The SO₄ ^2? ions formed by bacterially induced pyrite oxidation combined with bacterial (dissimilatory) dissolved sulfate reduction, and presumably with subordinate mineralization of carbon-bonded sulfur compounds, especially in both Marczakowe Do?y ponds. In addition, the comparison of δ¹⁸O–SO₄ ^2? and δ¹⁸O–H₂O values indicated that 75–100 % of sulfate oxygen was derived from water. Due to the largest size, the Podwi?niówka acid pit pond revealed distinct seasonal variations in both δ¹⁸O–H₂O (?9.2 to ?1.6) and δD–H₂O (?29.7 to ?71.3) values. The strong correlation coefficient (r ² = 0.99) was noted between δ¹⁸O–H₂O and δD–H₂O values, which points to atmospheric precipitation as the only source of water. The sediments of both acid ponds display different mineral inventory: the Marczakowe Do?y acid pond sediment consists of schwertmannite and goethite, whereas Podwi?niówka acid pit pond sediment is composed of quartz, illite, chlorite and kaolinite with some admixture of jarosite reflecting a more acidic environment. Geochemical modeling of two acid ponds indicated that the saturation indices of schwertmannite and nanosized ε-Fe₂O₃ (Fe³⁺ oxide polymorph) were closest to thermodynamic equilibrium state with water, varying from ?1.44 to 3.05 and from ?3.42 to 6.04, respectively. This evidence matches well with the obtained mineralogical results.  相似文献   

Effect of anisotropic conductivity on suction and reliability index of unsaturated slope exposed to uniform antecedent rainfall     

Khalid Mahmood  Jeong Ho Ryu  Jin Man Kim 《Landslides》2013,10(1):15-22

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Hydrogeochemical and isotopic study of the Kumho River, Korea: implications for anthropogenic and seasonal effects     

Yeongkyoo Kim  Kangjoo Kim 《Environmental Earth Sciences》2013,68(7):2051-2064

The geochemical and isotopic compositions of river water are controlled by different factors. The seasonal and spatial variations in the geochemical composition, δD, δ¹⁸O, and δ¹⁵N–NO₃ of the Kumho River were investigated to reveal the geochemical processes occurring at different seasons. The Kumho River, which runs through different geologic terrains with different land use characteristics, is the largest tributary of the Nakdong River, the longest river in South Korea. The data varied significantly according to the land use and the season. Each monitoring station showed the lowest concentrations of various ions during July, the rainy season, due to the increase of precipitation rate. The ionic concentrations gradually increased downstream by the mineral weathering and anthropogenic activity. At the upper regions of the river, Ca and HCO₃, which are closely associated with mineral weathering, were the most dominant cation and anion, respectively. The relatively high Si concentration of the headwater samples, caused by the weathering of volcanic rocks, also showed the importance of weathering in the upper regions mainly composed of volcanic rocks. The downstream regions of the Kumho River are mainly influenced by sedimentary rocks. At the lower reaches of the river, especially near the industrial complexes in Daegu, the third largest city in Korea, Na, Cl, and SO₄ became the dominant ions, indicating that the anthropogenic pollution became more important in regulating the chemical composition of the river. The increasing (Ca + Mg + Na + K)/HCO₃ ratio downstream also indicates that the anthropogenic effects became more important as the river flows downstream. The isotopic compositions of δD and δ¹⁸O indicate that the river waters were significantly affected by evaporation during May and July, but the evaporation effect was relatively low during October. The isotopic composition of δ¹⁵N–NO₃ increased downstream, also confirming that anthropogenic effects became more significant at the lower reach of the river and near Daegu.  相似文献   

A study on carbon dioxide emissions from bituminous coal in Korea     

Jeongwoo Lee  Chang-Sang Cho  Ki-hyup Hong  Jae-Hak Jeong  Seungjin Kim  Eui-Chan Jeon 《Environmental Earth Sciences》2013,70(4):1709-1715

Consumption of primary energy in Korea increased 5.25 % per year over a 10 years span starting in 1990. Korea ranked 8th in primary energy consumption in 2011; coal consumption increased 35 % from 87,827 million tons in 2006–119,321 tons in 2010. Heavy energy-consuming countries consistently conduct research to develop an emission factor of Tier 2 level, reflecting the characteristics of the fuel that they use. To calculate the emission factor of bituminous coal for fuel, this study developed emission factor and calculated emission amount by implementing fuel analysis on bituminous coal consumed in Korea between 2007 and 2009. CO₂ emission factor calculated by fuel analysis method is 95,315 kg/TJ, which is 0.75 % higher than the default value suggested by IPCC. The emission amount calculated by using the CO₂ emission factor in this study is 231.881 million tons, which has a difference of 1.739 million tons compared to the IPCC default value.  相似文献   

Studies of crosslinked biopolymer structure for environmental tools in terms of the rate of weight swelling ratio, viscosity, and biodegradability: part A     

Hsuan-Ting Lai  Daeik Kim  Joon-Seok Park  Teh Fu Yen 《Environmental Earth Sciences》2013,70(5):2405-2413

The crosslinking reaction caused by blending different biopolymers and/or adding a crosslinking agent to biopolymers was studied. The rate of crosslinking reaction was estimated with weight swelling ratio (WSR), viscosity, and biodegradability. The crosslinked material from blending two biopolymers or mixing a crosslinking agent with a mixture of two biopolymers showed a polymeric volume change, a high microbial resistance even after 80 days, and a viscosity increased because of chemical functional groups to form extensive intra- and interpenetrating polymer networks (IPNs). The organized IPN is a base block in building a three-dimensional (3-D) crosslinked biopolymer structure. This 3-D structure can be utilized in the environmental and geotechnical applications such as an environmental barrier or containment to encapsulate and treat hazardous materials against toxic flow in a subsurface engineering system.  相似文献   

Reductive dechlorination of polychlorinated biphenyls (PCBs) by ultrasound-assisted chemical process (UACP)     

J. R. Chen  Daeik Kim  Joon-Seok Park  Kyung-Ik Gil  Teh Fu Yen 《Environmental Earth Sciences》2013,69(3):1025-1032

The dechlorination of aqueous polychlorinated biphenyls (PCBs) using the ultrasound-assisted chemical process (UACP), which is a combination of ultrasonic irradiation and radical generations using di-tert-butyl peroxide as a radical initiator and ferrous ion as a catalyst at moderate temperature in alkaline 2-propanol, was demonstrated with a high reduction of PCBs. A commercial PCB-containing compound, Aroclor 1260, was also decomposed with the removal efficiency of 97 % achieved within 3 h of UACP. The gas chromatograph was used as a quantitative method to measure the decomposition rate of PCBs. The competitive elimination among the ortho (2-position), meta (3-position), and para (4-position) chlorine atoms of PCB was also identified.  相似文献