Size distributions of 29 elements in aerosols collected at urban,rural and curbside sites in Beijing were studied.High levels of Mn,Ni,As,Cd and Pb indicate the pollution of toxic heavy metals cannot be neglected in B...Size distributions of 29 elements in aerosols collected at urban,rural and curbside sites in Beijing were studied.High levels of Mn,Ni,As,Cd and Pb indicate the pollution of toxic heavy metals cannot be neglected in Beijing.Principal component analysis （PCA） indicates 4 sources of combustion emission,crust related sources,traffic related sources and volatile species from coal combustion.The elements can be roughly divided into 3 groups by size distribution and enrichment factors method （EFs）.Group 1 elements are crust related and mainly found within coarse mode including Al,Mg,Ca,Sc,Ti,Fe,Sr,Zr and Ba;Group 2 elements are fossil fuel related and mostly concentrated in accumulation mode including S,As,Se,Ag,Cd,Tl and Pb;Group 3 elements are multi-source related and show multi-mode distribution including Be,Na,K,Cr,Mn,Co,Ni,Cu,Zn,Ga,Mo,Sn and Sb.The EFs of Be,S,Cr,Co,Ni,Cu,Ga,Se,Mo,Ag,Cd,Sb,Tl and Pb show higher values in winter than in summer indicating sources of coal combustion for heating in winter.The abundance of Cu and Sb in coarse mode is about 2–6 times higher at curbside site than at urban site indicating their traffic sources.Coal burning may be the major source of Pb in Beijing since the phase out of leaded gasoline,as the EFs of Pb are comparable at both urban and curbside sites,and about two times higher in winter than that in summer.展开更多
While green landscapes are known to influence drivers'visual attention,the optimal configurations for enhancing driving safety and performance remain unclear.This study employed eyetracking technology to investiga...While green landscapes are known to influence drivers'visual attention,the optimal configurations for enhancing driving safety and performance remain unclear.This study employed eyetracking technology to investigate eye fixation and gaze behaviors of 24 drivers during a 90-minute simulated urban highway driving task across six distinct landscape conditions across three primary Areas of Interest(AOIs).Within-subject analysis of variance(ANOVA)comparing barren,turf,and woody landscapes revealed that increased greenness significantly directs drivers'eye movements towards greenery.Comparative analysis of the six landscape conditions suggested that shrub landscape settings achieved the most balanced distribution of visual attention across AOls,preventing drivers from excessively focusing on either natural or artificial features.Moreover,the ANOVA examining two shrub settings and two tree settings revealed a trade-off effect between landscape greenness and complexity.This study provides crucial empirical evidence for a balanced configuration of greenness and complexity in landscape design,confirming its critical role in achieving optimal visual perception outcomes.Finally,it proposes a triangular theoretical framework linking visual perception,mental states,and driving performance,offering theoretical support and practical reference for future research and design of healthy and safe driving environments.展开更多
基金supported by the special fund of the State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 11K03ESPCT)the National Department Public Benefit Research Foundation (Ministry of Environmental Protection of the People’s Republic of China) (No. 201009001,201109002)
文摘Size distributions of 29 elements in aerosols collected at urban,rural and curbside sites in Beijing were studied.High levels of Mn,Ni,As,Cd and Pb indicate the pollution of toxic heavy metals cannot be neglected in Beijing.Principal component analysis （PCA） indicates 4 sources of combustion emission,crust related sources,traffic related sources and volatile species from coal combustion.The elements can be roughly divided into 3 groups by size distribution and enrichment factors method （EFs）.Group 1 elements are crust related and mainly found within coarse mode including Al,Mg,Ca,Sc,Ti,Fe,Sr,Zr and Ba;Group 2 elements are fossil fuel related and mostly concentrated in accumulation mode including S,As,Se,Ag,Cd,Tl and Pb;Group 3 elements are multi-source related and show multi-mode distribution including Be,Na,K,Cr,Mn,Co,Ni,Cu,Zn,Ga,Mo,Sn and Sb.The EFs of Be,S,Cr,Co,Ni,Cu,Ga,Se,Mo,Ag,Cd,Sb,Tl and Pb show higher values in winter than in summer indicating sources of coal combustion for heating in winter.The abundance of Cu and Sb in coarse mode is about 2–6 times higher at curbside site than at urban site indicating their traffic sources.Coal burning may be the major source of Pb in Beijing since the phase out of leaded gasoline,as the EFs of Pb are comparable at both urban and curbside sites,and about two times higher in winter than that in summer.
文摘While green landscapes are known to influence drivers'visual attention,the optimal configurations for enhancing driving safety and performance remain unclear.This study employed eyetracking technology to investigate eye fixation and gaze behaviors of 24 drivers during a 90-minute simulated urban highway driving task across six distinct landscape conditions across three primary Areas of Interest(AOIs).Within-subject analysis of variance(ANOVA)comparing barren,turf,and woody landscapes revealed that increased greenness significantly directs drivers'eye movements towards greenery.Comparative analysis of the six landscape conditions suggested that shrub landscape settings achieved the most balanced distribution of visual attention across AOls,preventing drivers from excessively focusing on either natural or artificial features.Moreover,the ANOVA examining two shrub settings and two tree settings revealed a trade-off effect between landscape greenness and complexity.This study provides crucial empirical evidence for a balanced configuration of greenness and complexity in landscape design,confirming its critical role in achieving optimal visual perception outcomes.Finally,it proposes a triangular theoretical framework linking visual perception,mental states,and driving performance,offering theoretical support and practical reference for future research and design of healthy and safe driving environments.
