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The quantity and quality of cropland plays an important role in ensuring food security. In order to explore spatiotemporal patterns of the extent to which cropland satisfies people's grain need, we integrate multi-source heterogeneous data to investigate in which era, and in which region, the cultivated land can meet people's food demands. It turns out that in the past 30 years, with the exception of the late 1980s, the amount of cropland could satisfy people's grain needs at the nation scale. However, more than 10 provinces (municipality/autonomous region), mainly located in western China and southeast coastal areas, have been unable to meet the grain needs of local people. We projected the guarantee rate to the late 2020s. Our study concludes that the guarantee rate of cropland is estimated to be higher than 150% in China. Compared to 2019, except Beijing, Tianjin, Liaoning, Jilin, Ningxia, as well as Heilongjiang in the Sustainability scenario, and Shanghai in the Sustainability and the Equality scenarios, the guarantee rate of cultivated land will increase in every province (municipality/autonomous region) in 2030. This study has reference value for the study of China's cultivated land protection system, as well as important significance for China's sustainable development. [ABSTRACT FROM AUTHOR]

Abstract: Sediments of Chinese tamarisk (Tamarix chinensis Lour.) nebkhas in China''s arid Ala Shan Plateau document both the formation processes of these vegetated dunes and the environmental changes and geomorphological evolution in this region. Dating of the nebkhas showed that after surface water disappeared, the wadis and playas evolved into gobi deserts (desert pavements) within two centuries. The δ13C trends in the litter deposited within the nebkhas revealed three stages of fluctuating moisture conditions during the past five centuries: before the 1580s, between the 1580s and the late 1990s, and from the early 2000s to the present. However, changes in the coarse fraction of the nebkha sediments show that this region experienced at least five phases of aeolian sediment transport during the same period. The early stages of nebkha formation coincided with the initial stage, when the wadis and playas evolved into gobi deserts and nebkha sizes increased rapidly due to the abundant sediment supply provided by the playas. However, after the playa surfaces stabilized, the nebkha sediments documented environmental changes in adjacent regions. Our results also show that the formation of the Tamarix nebkhas in this region was not controlled by the groundwater table, because in most periods, the water table depth remained above the depth that limits Tamarix survival. In the Ala Shan Plateau, nebkha formation was mainly controlled by aeolian processes, and revealed the integrated effects of environmental changes, thereby providing possibilities for climate and environment reconstructions with a relatively high resolution in extremely arid areas. [Copyright &y& Elsevier]

Abstract: A source analysis to characterize the composition of dust fallout in arid and semiarid North China, an important source area of dust for East Asia, was performed. Monthly samples were obtained from April 2001 to March 2002 at 29 sites in sandy and gobi deserts, steppes, and loess areas, and the following elements were analyzed: Ce, Co, Cs, Eu, Fe, Hf, Lu, Nd, Rb, Sc, Ta, Tb, Th, As, La, Na, Sb, Sm, U, Yb, Al, Ca, Mg, Mn, Ti, and V. Although the dust compositions differed, it was difficult to determine the potential dust source areas based solely on the elemental fingerprints of the dust. Principal components analysis showed that at most sites Sm, Sc, La, Ce, Eu, and Th were most strongly correlated (r >0.7) with other elements, whereas crustal elements such as Al, Fe, and Ti were only strongly correlated with the other elements at a few sites. Of the 26 elements that we analyzed, maybe only Sb was representative of anthropogenic pollution, but pollutant sources were unclear because at most sites, in different months, the crustal-derived elements and those derived from anthropogenic pollutants always appeared synchronously, creating difficulties and high uncertainties in source identification. [Copyright &y& Elsevier]

Abstract: Most areas of arid and semiarid China are covered by aeolian sand dunes, sand sheets, and desert steppes, and the existence of the nearly 80 million people who live in this region could be seriously jeopardized if climate change increases desertification. However, the expected trends in desertification during the 21st century are poorly understood. In the present study, we selected the ECHAM4 and HadCM3 global climate models (after comparing them with the results of the GFDL-R30, CGCM2, and CSIRO-Mk2b models) and used simulations of a dune mobility index under IPCC SRES climate scenarios A1FI, A2a, A2b, A2c, B1a, B2a, and B2b to estimate future trends in dune activity and desertification in China. Although uncertainties in climate predictions mean that there is still far to go before we can develop a comprehensive dune activity estimation system, HadCM3 simulations with most greenhouse forcing scenarios showed decreased desertification in most western region of arid and semiarid China by 2039, but increased desertification thereafter, whereas ECHAM4 simulation results showed that desertification will increase during this period. Inhabitants of thecentral region will benefit from reversed desertification from 2010 to 2099, whereas inhabitants of the eastern region will suffer from increased desertification from 2010 to 2099. From 2010 to 2039, most regions will not be significantly affected by desertification, but from 2040 to 2099, the environments of the western and eastern regions will deteriorate due to the significant effects of global warming (particularly the interaction between precipitation and potential evapotranspiration), leading to decreased livestock and grain yields and possibly threatening China''s food security. [Copyright &y& Elsevier]

Abstract: Objective.: To identify modifiable family and school environmental factors associated with Chinese adolescent smoking behaviors including never-smoking, experimental smoking, regular smoking, and attempting to quit. Methods.: A cross-sectional survey using self-reported questionnaires was conducted in Huangpu, Guangzhou in December of 2004. A total of 3957 pupils agreed to complete the questionnaires. The prevalence odds ratio (risk) of experimental smoking was compared to never-smoking, adjusting for gender and age in unconditional logistic regression analysis. The risk of regular smoking was compared to experimental smoking, and the risk of attempting quitting was analyzed in regular smokers. Results.: The cigarette smoking of peers, mothers, fathers, brothers, and supervising teachers, passive smoking, and seeing someone smoking on campus increased the risk of experimental smoking vs. nonsmoking, while no-smoking signs, perceived anti-tobacco atmosphere in school, and being taught smoking-related health knowledge decreased the risk. The factors associated with regular smoking compared to experimental smoking included the smoking of peers, brothers, fathers and supervising teachers, teacher''s tolerance, and passive smoking. Being taught smoking-related knowledge, perceived anti-tobacco atmosphere and no-smoking signs in school were positively associated with regular smoker''s attempt to quit, while supervising teacher''s smoking, parents'' and teachers'' tolerance could delay it. Conclusions.: These modifiable family and school environmental factors as well as their interaction with gender and age should be highly considered in adolescent smoking prevention in China. [Copyright &y& Elsevier]

• Dust emissions triggered by desertification in China are evaluated. • From 1970 to 2015, the mean PM 10 emitted in desertified lands is 29.40 Tg yr−1. • After the 2000s dust emissions in desertified lands decreased by 75%. • Spatio-temporal variations in dust emissions triggered by desertification existed. The spatial and temporal trends of potential dust emissions from severe aeolian desertified lands and Gobi desert surfaces in China were investigated based on field sample collections, wind tunnel experiments, and historical wind records. The results showed that aeolian desertified lands and Gobi desert surfaces are both key landscapes for dust emissions. The dust emission rate in Gobi deserts was approximately 19% of what originated from desertified lands at the beginning of the 1970s but this ratio increased to 26% in 2015. Considering temporal variations of dust emission over aeolian desertified lands and the Gobi desert surfaces, from the 1980s to the present, the contribution of the Gobi desert surfaces on dust emissions decreased from 71% to 31% of that originating in desertified lands. From the 1970s to 2015, the average amounts of PM 2.5 (particulate matter with diameter less than 2.5 μm), PM 5 , PM 10 , and PM 50 emitted from desertified lands are 17.6, 29.4, 39.6, and 65.2 Tg yr−1, while that of PM 5 , PM 10 , and PM 50 emitted from the Gobi desert surfaces are 18.4, 26.5, 40.4 Tg yr−1, respectively. Compared with that in the 1970s, potential dust emissions after 2000 from desertified lands and the Gobi desert surfaces decreased by 75% and 71%, respectively. In addition, the wind tunnel experiment results and statistics indicate that the potential dust emissions in China are far lower than that of model simulations. There are significant spatio-temporal variations in the potential dust aerosol source areas and intensities of dust emissions in China over the past decades. [ABSTRACT FROM AUTHOR]