You see these quite often around the city. I saw this particular notice at the entrance to a park, pasted onto a sign telling people that it is forbidden to bring bikes in.
"Huang Donghua went missing on 8 August, after leaving home in an upset and confused state. Anyone with information should call the family. There is a reward between 8000-10000 RMB [1170-1464 USD]."
The noticeboard at the East Bus Station had several missing person notices when I was there earlier this year: