Sampling sites: 1, Yangjiang county, Guangdong province (GDYJ); 2, Rong county, Zigong city, Sichuan province (ZGRX); 3, Xichang city, Liangshan prefecture, Sichuan province (LSXC); 4, Lizhou county, Liangshan prefecture, Sichuan province (LSLZ); 5, Dali city, Yunnan province (YNDL); 6, Xuancheng city, Anhui province (AHXC); 7, Huai’an city, Jiangsu province (JSHA); 8, Wenzhou city, Zhejiang province (ZJWZ); 9, Tai’an City, Shandong province (SDTA); 10, Chongqing Municipality (ZGCQ).