Funding for this research was provided by:
National Geographic Air and Water Conservation Fund (GSFC10–13)
Article History
Received: 31 October 2019
Accepted: 6 February 2020
First Online: 18 February 2020
Compliance With Ethical Standards
:
: The authors declare that they have no conflict of interest.
: The research protocol was approved by the institutional review board of Peking University (code: IRB00001052–14019), and informed consent was obtained from the subjects before the investigation.