“…Spatial discontinuity of arsenic concentration has been reported in Bangladesh (Radloff et al, 2017), West Bengal in India (Biswas et al, 2014), China (Cai et al, 2015;Ma et al, 2016), Chianan Plain of Taiwan (Sengupta et al, 2014), Mekong Delta of Vietnam (Wilbers et al, 2014), the southern Pampa of Argentina (Díaz et al, 2016), the Duero River Basin of Spain (Pardo-Igúzquiza et al, 2015), Nova Scotia in Canada (Dummer et al, 2015), Wisconsin in the USA (Luczaj et al, 2015), the Águeda watershed area in Portuguese district of Guarda and the Spanish provinces of Salamanca and Caceres (Antunes et al, 2014), and so on.…”