2012~2019年天津市公交站微环境空气质量改善

于2012年9月、2014年3月、2015年6月和2019年6月在天津市八里台公交站采集环境空气样品，分析该微环境中大气可吸入颗粒物（PM₁₀）污染的整体改善趋势以及PM₁₀中碳组分、水溶性离子组分以及元素组分的特征和4次采样之间的差异.结果表明，4次采样的PM₁₀浓度分别为281，217，188，78μg/m³，呈明显下降趋势.其中水溶性离子组分和元素组分浓度逐年降低，但其占比变化不大（平均浓度占比分别为22%和39%），4次采样的二次离子SNA（即SO₄^2-，NO₃^-和NH₄⁺）占PM₁₀比例分别为11%，9%，9%，17%；总碳质量浓度逐年降低，碳组分在PM₁₀中所占的比例呈波动上升的趋势（从18%上升至32%，平均为25%），根据估算结果，4次采样的二次有机碳（SOC）占PM₁₀比例分别为4%，9%，9%，13%.研究显示，天津市交通微环境空气质量改善效果显著，但二次组分（SNA和SOC）在PM₁₀中占比呈上升趋势，需进一步加强二次污染的控制.

Comparison of fungal community structure and diversity in typical paddy fields

To understand the differences in fungal community structure and diversity in paddy field soils developed from different parent materials in the main rice growing areas of China, five typical paddy soils, i.e., latosol, red soil, saline alkali soil, black soil and purple soil, were analyzed for the fungi species composition and community diversity by high-throughput sequencing technology. Soil water content, pH, salinity, and bulk density were significantly different (P<0.05) beween the five typical paddy soils. Chao1index indicated that the richness of the fungal community in the paddy soil types was in the order of red soil > black soil > latosol > purple soil > saline-alkali soil. The ACE index suggested that the richness of the fungal communities was in the order of black soil > red soil > latosol > purple soil > saline-alkali soil. Both Shannon index and Simpson index of community diversity were in the order of black soil > purple soil > red soil > latosol > saline-alkali soil. The phylum with the highest relative abundance was Ascomycota in all five typical paddy soils. The dominant fungi genera were Emericellopsis, (Emericellopsis, Cladorrhinum and Zopfiella), (Emericellopsis and Monographella), and Phialocephala for the paddy soils developed from latosol and red soil, purple soil, black soil and saline alkali soil, respectively. The relative abundance of Xanthoria, Cyberlindnera, Penicillium, and Westerdykella were significantly and negatively correlated with soil pH (P<0.05). Furthermore, the relative abundance of Ceroophora was significantly and negatively correlated with soil water content, and the relative abundance of Sarocladium was significantly and positively with dissolved organic carbon (P<0.01) across soil types. The fungi community structure and diversity were significantly affected by the paddy soil developed from previous reclamation types, and the fungi genera richness and dominant genera were sensitive to the changes of soil physical and chemical properties.