This research investigates the experiences of Chinese heritage language learners (CHLLs) in a federally funded program of Teaching Chinese as a Foreign Language in the United States. Most pertinent studies on Chinese heritage language education focus on stakeholders such as teachers and parents. Instead, this study explores the agency of heritage language learners in their efforts toward heritage language maintenance. Adopting a three-pronged conceptual framework of language planning and policy as a sociocultural process, language ideology, and language identity, this study applies an ethnographically-informed qualitative approach to understanding how CHLLs develop and exercise implicit language policies—taken-for-granted norms about language that guide their language choices and practices—their language ideologies that undergird these policies and the relationship of these informal policies to these learners’ language identities.

This study suggests CHLLs participate in Chinese learning activities to reconnect to their family and culture. Their language maintenance efforts, however, do not necessarily change their language use dramatically. In CHLLs’ everyday social interactions, their language choices depend on the interlocutors, locations and topics of the conversation and are impacted by the dominant language ideologies toward Chinese and English. CHLLs’ Chinese language maintenance practices strengthen learners’ relationship with both the language and culture. But Chinese language can be absent from learners’ pursuit of their cultural heritage. Furthermore, the multilayered identities of CHLLs are constructed and negotiated in the heteroglossic and multicultural environments.

This is an endeavor in connecting the initiatives of increasing foreign language capacity at the national level with the efforts of maintaining heritage language at the individual level. This study can contribute to a holistic picture for teachers and parents to understand CHLLs’ language learning experience. It also offers strategies that can benefit heritage language education.

Using a CH[subscript 4]-based membrane biofilm reactor (MBfR), we studied perchlorate (ClO[subscript 4]–) reduction by a biofilm performing anaerobic methane oxidation coupled to denitrification (ANMO-D). We focused on the effects of nitrate (NO[subscript 3]–) and nitrite (NO[subscript 2]–) surface loadings on ClO[subscript 4]– reduction and on the biofilm community’s mechanism for ClO[subscript 4]– reduction. The ANMO-D biofilm reduced up to 5 mg/L of ClO[subscript 4]– to a nondetectable level using CH[subscript 4] as the only electron donor and carbon source when CH[subscript 4] delivery was not limiting; NO[subscript 3]– was completely reduced as well when its surface loading was ≤0.32 g N/m[superscript 2]-d. When CH[subscript 4] delivery was limiting, NO[subscript 3]– inhibited ClO[subscript 4]– reduction by competing for the scarce electron donor. NO[subscript 2]– inhibited ClO[subscript 4]– reduction when its surface loading was ≥0.10 g N/m[superscript 2]-d, probably because of cellular toxicity. Although Archaea were present through all stages, Bacteria dominated the ClO[subscript 4]–-reducing ANMO-D biofilm, and gene copies of the particulate methane mono-oxygenase (pMMO) correlated to the increase of respiratory gene copies. These pieces of evidence support that ClO[subscript 4]– reduction by the MBfR biofilm involved chlorite (ClO[subscript 2]–) dismutation to generate the O[subscript 2] needed as a cosubstrate for the mono-oxygenation of CH[subscript 4].