Part physical and chemical characteristics of dust aerosol were determined for samples collected from Otindag Sandland of China in spring, 2001. Number con- centration, mass concentration, chemical element concentra- ...Part physical and chemical characteristics of dust aerosol were determined for samples collected from Otindag Sandland of China in spring, 2001. Number con- centration, mass concentration, chemical element concentra- tion and size distribution of aerosol particles with 0.5 μ m < Dp < 100.0 μ m were examined. The average number and mass concentrations of aerosols were 274.8 cm-3 and 0.54 mg/m3 for the field period respectively, and 31.4 cm-3 and 0.07 mg/m3 for the non-dusty days. PM10 played a dominant role in the aerosol mass concentrations. The particles with Dp < 8.0 μ m accounted for about 93.7% of total aerosol number loading in dusty days. The particle size distributions of aero- sols were characterized by bi-modal logarithm normal func- tion in heavy and moderate dusty days, and mono-modal in windblown and non-dusty days. Crustal elements such as Al, Fe, etc. in aerosols almost originated from soils. Pollutant elements of S, Pb, etc. associated with aerosols were affected by remote anthropogenic pollutant sources in upwind regions. Mo, V and Co in aerosols were possibly from other dust sources other than local soils. The aerosols over Otindag Sandland consisted of particles from local soils, upwind pol- lutant sources and other dust sources.展开更多
Responses of caryopsis germination, seedling emergence, and development of Agropyron cristatum （L.） Gaertn. （Gramineae） and Bromus inermis Leyss. （Gramineae）, two dominant perennial grasses in the Otindag Sandla...Responses of caryopsis germination, seedling emergence, and development of Agropyron cristatum （L.） Gaertn. （Gramineae） and Bromus inermis Leyss. （Gramineae）, two dominant perennial grasses in the Otindag Sandland of China, to different sand water content （SWC; 1%, 2%, 3%, 4%, 6%, 8%, 12%, 16%, and 20%） were studied comparatively. The results showed that the germination responses of the two grasses to SWC were similar （i.e. caryopses could not germinate when the SWC was below 3%; at SWC ranging from 3% to 12%, the higher the SWC, the higher the germination percentage; and at a SWC of 12%-20%, germination reached similarly high percentages）. At a sand burial depth of 0.5 cm, the threshold of SWC for seedling emergence was 6% forA. cristatum and 8% forB. inermis; at 12%-20% SWC, the seedling emergence of both species reached similarly high percentages. The seedling growth responses of these two species to SWC gradients were different. For A. cristatum, the biomass of seedlings increased with SWC from 6% to 12%, and decreased with SWC from 12% to 20%. For B. inermis, the biomass of seedlings always increased with SWC from 8% to 20%. The results also showed that the seedlings of both species allocated more biomass to the roots with decreases in SWC. The SWC changes from April to October in natural microhabitats of both species suggested that the SWC may play an important role in caryopsis germination, seedling emergence, and the growth characteristics of the two grasses. The responses of caryopsis germination, seedling emergence, and the growth characteristics of these two species to SWC may determine their distribution pattems in the Otindag Sandland.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.49790020).
文摘Part physical and chemical characteristics of dust aerosol were determined for samples collected from Otindag Sandland of China in spring, 2001. Number con- centration, mass concentration, chemical element concentra- tion and size distribution of aerosol particles with 0.5 μ m < Dp < 100.0 μ m were examined. The average number and mass concentrations of aerosols were 274.8 cm-3 and 0.54 mg/m3 for the field period respectively, and 31.4 cm-3 and 0.07 mg/m3 for the non-dusty days. PM10 played a dominant role in the aerosol mass concentrations. The particles with Dp < 8.0 μ m accounted for about 93.7% of total aerosol number loading in dusty days. The particle size distributions of aero- sols were characterized by bi-modal logarithm normal func- tion in heavy and moderate dusty days, and mono-modal in windblown and non-dusty days. Crustal elements such as Al, Fe, etc. in aerosols almost originated from soils. Pollutant elements of S, Pb, etc. associated with aerosols were affected by remote anthropogenic pollutant sources in upwind regions. Mo, V and Co in aerosols were possibly from other dust sources other than local soils. The aerosols over Otindag Sandland consisted of particles from local soils, upwind pol- lutant sources and other dust sources.
基金国家重点基础研究发展计划(973计划)，the National Natural Science Foundation of China，the Knowledge Innovation Program of the Chinese Academy of Sciences
文摘Responses of caryopsis germination, seedling emergence, and development of Agropyron cristatum （L.） Gaertn. （Gramineae） and Bromus inermis Leyss. （Gramineae）, two dominant perennial grasses in the Otindag Sandland of China, to different sand water content （SWC; 1%, 2%, 3%, 4%, 6%, 8%, 12%, 16%, and 20%） were studied comparatively. The results showed that the germination responses of the two grasses to SWC were similar （i.e. caryopses could not germinate when the SWC was below 3%; at SWC ranging from 3% to 12%, the higher the SWC, the higher the germination percentage; and at a SWC of 12%-20%, germination reached similarly high percentages）. At a sand burial depth of 0.5 cm, the threshold of SWC for seedling emergence was 6% forA. cristatum and 8% forB. inermis; at 12%-20% SWC, the seedling emergence of both species reached similarly high percentages. The seedling growth responses of these two species to SWC gradients were different. For A. cristatum, the biomass of seedlings increased with SWC from 6% to 12%, and decreased with SWC from 12% to 20%. For B. inermis, the biomass of seedlings always increased with SWC from 8% to 20%. The results also showed that the seedlings of both species allocated more biomass to the roots with decreases in SWC. The SWC changes from April to October in natural microhabitats of both species suggested that the SWC may play an important role in caryopsis germination, seedling emergence, and the growth characteristics of the two grasses. The responses of caryopsis germination, seedling emergence, and the growth characteristics of these two species to SWC may determine their distribution pattems in the Otindag Sandland.
