Responses of phytoliths in topsoil samples to temperature variation in temperate region.

Modern phytolith research is the premise to accurately reconstruct the regional paleovegetation and paleoclimate. It is thus particularly important to study the spatial distribution characteristics of the phytolith assemblages and the response of the phytolith to environmental factors. In this study, we collected 54 topsoil samples along the isohyet of 600 mm in Northeast China to examine the distribution patterns of phytolith along the gradient of single environmental factor. With this special sampling method, we targeted to reveal the responses of phytolith assemblages in the topsoil to the variation of temperature. The results showed that there were a large number of phytoliths with various morphotypes in the 54 topsoil samples in Northeast China. The phytolith morphotypes were the same, including elongate, lanceolate, blocky, cuneiform, tabular, saddle, rondel, bilobate, trapeziform polylobate, prism, silicified stomata, conduit, papillae, sclereid and carinate. In gene-ral, the contributions of elongate and lanceolate were high; the contributions of short cell phytoliths, blocky, tabular and cuneiform were small relatively; the contributions of the other types of phytoliths were less than 1.0% and appeared sporadically in the topsoil samples. Besides, the phytolith assemblages of the topsoil samples were different among Xiaoxing'an Mountains, Songliao Plain and Liaoxi hills. Combined with the discriminant analysis, the samples from the three regions could be effectively separated based on the phytoliths assemblages, with a total accuracy of 94.4%. Specifi-cally, the average percentage of elongate, lanceolate, prism was the largest in Xiaoxing'an Mountains, and was the smallest in Liaoxi hills; the percentage of saddle, bilobate, papillae was the largest in Liaoxi hills and the smallest in Xiaoxing'an Mountains; the percentage of blocky, tabular, cuneiform was the largest in Songliao Plain. Meanwhile, the percentages of the elongate, lanceolate, prism, saddle, bilobate, papillae, blocky, tabular, cuneiform were significant diffe-rences among the three regions. There were significant negative correlations between the percentages of elongate, lanceolate, prism and the annual average temperature, and positive relationships between the percentages of the blocky, tabular, cuneiform, bilobate, papillae and the annual average temperature. However, the percentage of saddle, rondel and trapeziform polylobate did not change with increasing annual average temperature.

Chemical characteristics of aerosol particles (PM2.5) at a site of Horqin Sand-land in northeast China.

The objective of this study was to characterize the mass concentration and chemical composition of aerosol particles (PM2.5) collected at Tongliao (Inner Mongolia Autonomous Region, China), a site in Horqin Sand-land in northeast China. During spring 2005, the mass concentration for PM2.5 was (126 +/- 71)microg/m3 in average. Five dust storm events were monitored with higher concentration of (255 +/- 77)microg/m3 in average than the non dusty days of (106 +/- 44)microg/m3. Concentrations for 20 elements were obtained by the PIXE method. Mass concentrations of Al, Mg, Si, K, Ca, Ti, Mn, and V, which increased with the PM2.5 concentration, were higher than the pollution elements (S, Cl, Zn, Ar, Se, Br, and Pb). Enrichment factor relative to crust material was also calculated, which showed dust trace elements were mainly from earth upper crust and pollution elements were dominated the anthropogenic aerosols. The Si/Al, Ca/Al, and Fe/Al ratios in PM2.5 samples at Tongliao were 4.07, 0.94, and 0.82, respectively, which were remarkably different with those on other source regions, such as "Western desert source region", "North desert source region" and central Asia source. Air mass back-trajectory analysis identified three kinds of general pathways were associated with the aerosol particle transport to Tongliao, but have the similar elemental ratios, implying that elemental signatures for dust aerosol from Horqin Sand-land were different with other regions.

[The material character of sand dust and analysis on the cause of formation of the sand-dust storm in northeast district in spring of 2002].

The paper analyzed the particle distribution, pollen combination of sand dust storm in northeast district in spring, 2002. It was found that there is abundant pollen, based on pollen combination sand source at new angle can be analyzed, and the distribution laws of the bowling sand and sand dust storm in season, in yearly, in geological periods and mankind historic periods can be explained. The blowing sand and sand dust storm often appeared in geological period and mankind historic period in northeast district, and mainly appeared in winter and in spring and they dropped fluctuationally in fifty years. The frequency of the sand dust storm increased since 2000. The frequency of blowing sand and sand dust storm was controlled by the strength of the monsoon wind in winter. Which the Enino and anti-Enino alternately occurs was influenced by the periodic change of the strength of monsoon wind in winter in Eastern Asia. The cold and dry climate combination in winter and spring was favorable of the occurrence of sand dust weather. The frequency of the sand dust weather will not obviously increase in several years.