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Climate conditions can significantly alter the vegetation net primary productivity (NPP) in many of Earth's ecosystems, although specifics of NPP–climate condition interactions, especially time-lag responses on seasonal scales, remain unclear in ecologically sensitive forest–grassland ecotones. Based on the Moderate-Resolution Imaging Spectroradiometer (MODIS) and meteorological datasets, we analyzed the relationship between NPP and precipitation, temperature, and drought during the growing season (April–August), considering the time-lag effect (0–5 months) at the seasonal scale in Hulunbuir, Inner Mongolia, China from 2000 to 2018. The results revealed a delayed NPP response to precipitation and drought throughout the growing season. In April, the precipitation in the 4 months before (i.e., the winter of the previous year) explained the variation in NPP. In August, the NPP in some areas was influenced by the preceding 1~2 months of drought. The time-lag effect varied with vegetation type and soil texture at different spatial patterns. Compared to grass and crop, broadleaf forest and meadow exhibited a longer legacy of precipitation during the growing season. The length of the time-lag effects of drought on NPP increased with increasing soil clay content during the growing season. The interaction of vegetation types and soil textures can explain 37% of the change in the time-lag effect of the NPP response to PPT on spatial pattern. Our findings suggested that preceding precipitation influences vegetation growth at the early stages of growth, while preceding drought influences vegetation growth in the later stages of growth. The spatial pattern of the time lag was significantly influenced by interaction between vegetation type and soil texture factors. This study highlights the importance of considering the time-lag effects of climate conditions and underlying drivers in further improving the prediction accuracy of NPP and carbon sinks in temperate semiarid forest–grassland ecotones. [ABSTRACT FROM AUTHOR]

Abstract: Coalfield fires are hazardous to the environment and human health as a result of the release of polycyclic aromatic hydrocarbons (PAHs). The incomplete combustion processes of the Ulanqab lignite from Inner Mongolia of northern China during coalfield fires were simulated in a tubular furnace, and 16 US Environmental Protection Agency priority pollutant PAHs in the flue gas were absorbed and analyzed. The results indicate that incomplete combustion results in a clear increase in PAH emission compared with other combustion methods; this is attributed to the formation of species with two and three benzene rings, such as naphthalene, acenaphthylene, and acenaphthene. Benzo[a]pyrene, dibenz[a,h]anthracene, and benz[a]anthracene make a large contribution to the toxicity equivalent value (TEQ), although they make up a small proportion of the PAHs. With temperature increasing, the total PAH yield peak occurs at 800°C with a yield of 923.41mg/kg at an air/coal ratio of 1m3/kg. As the air/coal ratio increases, the amount of PAHs varies with the addition of oxygen. At a ratio of 2m3/kg, the minimum PAH yield of 486.07mg/kg occurs at 800°C and the maximum concentrations of the most toxic species, benzo[a]pyrene, and dibenz[a,h]anthracene, are found. Increasing the coal particle size from 0.25 to 20mm results in a significant growth of both the yields and TEQs of the PAH species. [Copyright &y& Elsevier]