A 'Concentrate-&-Destroy' technology for enhanced removal and destruction of per- and polyfluoroalkyl substances in municipal landfill leachate.

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in landfill leachate due to their widespread applications in various industrial and consumer products. Yet, there has been no cost-effective technology available for treating PFAS in leachate because of the intrinsic persistency of PFAS and the high matrix strength of landfill leachate. We tested a two-step 'Concentrate-&-Destroy' technology for treating over 14 PFAS from a model landfill leachate through bench- and pilot-scale experiments. The technology was based on an adsorptive photocatalyst (Fe/TNTs@AC), which was able to selectively adsorb PFAS despite the strong matrix effect of the leachate. Moreover, the pre-concentrated PFAS on Fe/TNTs@AC were effectively degraded under UV, which also regenerates the material. The presence of 0.5 M H2O2 during the photocatalytic degradation enhanced the solid-phase destruction of the PFAS. Fresh Fe/TNTs@AC at a dosage of 10 g/L removed >95% of 13 PFAS from the leachate, 86% after first regeneration, and 74% when reused three times. Fe/TNTs@AC was less effective for PFBA and PFPeA partially due to the transformation of precursors and/or longer-chain homologues into these short-chain PFAS. Pilot-scale tests preliminarily confirmed the bench-scale results. Despite the strong interference from additional suspended solids, Fe/TNTs@AC removed >92% of 18 PFAS in 8 h under the field conditions, and when the PFAS-laden solids were subjected to the UV-H2O2 system, ~84% of 16 PFAS in the solid phase were degraded. The 'Concentrate-&-Destroy' strategy appears promising for more cost-effective removal and degradation of PFAS in landfill leachate or PFAS-laden high-strength wastewaters.

Changes in China's lakes: climate and human impacts.

Lakes have played a critical role in providing water and ecosystem services for people and other organisms in China for millennia. However, accelerating climate change and economic boom have resulted in unprecedented changes in these valuable lakes. Using Landsat images covering the entity of the country, we explored the changes in China's lakes and the associated driving forces over the last 30 years (i.e. mid-1980s to 2015). We discovered that China's lakes have changed with divergent regional trends: in the sparsely populated Tibetan Plateau, lakes are abundant and the lake area has increased dramatically from 38 596 to 46 831 km2 (i.e. increased by 8235 km2, or 21.3%), whereas, in the densely populated northern and eastern regions, lakes are relatively scarce and the lake area has decreased from 36 659 to 33 657 km2 (i.e. decreased by 3002 km2, or 8.2%). In particular, severe lake decreases occurred in the Mongolia-Xinjiang Plateau and the Eastern Plain (-2151 km2). Statistical analyses indicated that climate was the most important factor controlling lake changes in the Tibetan Plateau, the Yun-Gui Plateau and the Northeast Plain. However, the strength of climatic control on lake changes was low in the Eastern Plain and the Mongolia-Xinjiang Plateau, where human activities, e.g. impoldering, irrigation and mining, have caused serious impacts on lakes. Further lake changes will exacerbate regional imbalances between lake resources and population distribution, and thus may increase the risk of water-resource crises in China.

Patterns and determinants of wood physical and mechanical properties across major tree species in China.

The physical and mechanical properties of wood affect the growth and development of trees, and also act as the main criteria when determining wood usage. Our understanding on patterns and controls of wood physical and mechanical properties could provide benefits for forestry management and bases for wood application and forest tree breeding. However, current studies on wood properties mainly focus on wood density and ignore other wood physical properties. In this study, we established a comprehensive database of wood physical properties across major tree species in China. Based on this database, we explored spatial patterns and driving factors of wood properties across major tree species in China. Our results showed that (i) compared with wood density, air-dried density, tangential shrinkage coefficient and resilience provide more accuracy and higher explanation power when used as the evaluation index of wood physical properties. (ii) Among life form, climatic and edaphic variables, life form is the dominant factor shaping spatial patterns of wood physical properties, climatic factors the next, and edaphic factors have the least effects, suggesting that the effects of climatic factors on spatial variations of wood properties are indirectly induced by their effects on species distribution.