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The sediments of closed-basin lakes on the margin of the East Asian summer monsoon (EASM) are valuable archives of past changes in hydroclimate and dust activity and thus potentially can help us to understand future climate changes. We present high-resolution, well-dated records of the grain size and carbonate mineralogy from Lake Bayanchagan, northern China, spanning the last 11.5 ka. Grain-size endmember (EM) analysis distinguished four EMs, each linked to different sediment transport processes. EM1 (0.4–0.6 μm) and EM3 (14–102 μm) reflect the strength of regional dust activity, whereas EM2 (1.3–31 μm) represents variations in local hydrodynamic conditions related to lake-level changes and EM4 (68–500 μm) is associated with local dust activity. Our results show that a high lake level and weakened dust activity occurred during 10–5.8 ka, as indicated by increased EM2 and decreased EM3, respectively. After 5.8 ka, EM2 decreased as the three other EMs increased, and dolomite appeared in the sediments while calcite decreased—indicating both a decline in lake level and strengthened dust activity. The fluctuations in lake level and dust activity are in good agreement with precipitation variations reconstructed from other records, which are in turn correlated to movement of the EASM rainfall belt, in response to temperature changes. [ABSTRACT FROM AUTHOR]

Affordance refers to the opportunity available to a learning activity. Taking affordance as a theoretical and analytical construct, this exploratory study investigates learners' attitudes and the opportunities WeChat may provide for Chinese cultural knowledge (CCK) learning. The aim is to find out the potential new affordances and compare learners with different language levels. 24 participants were paired with native Chinese speakers and required to complete three-stage activities with the integration of WeChat. This study adopted a mix-method approach. Data were collected through questionnaires, two rounds of semi-structured interviews, chat logs, and WeChat moments. It is found that most learners were positive toward the activities and WeChat provided learners with opportunities for interaction and collaboration, for resource sharing, for knowledge internalization and construction, and for sustainable learning and friendship maintaining. The affordance of knowledge internalization and construction was mentioned with the highest frequency in the interview. The findings that distinguish this study from previous ones are: (1) the affordance for sustainable learning, and (2) differences between high-level (HL) and low-level (LL) learners. In comparison, the activities won more supports from HL learners, and HL learners' frequency in leveraging the affordance for resource sharing and sustainable learning was also higher. Pedagogical implications and research recommendations were provided respectively in discussion and conclusion parts. [ABSTRACT FROM AUTHOR]