Page 54 - AWSAR 2.0

30 || AWSAR Awarded Popular Science Stories - 2019
such as the development of
cancer, hence called as ‘worst
mass poisoning’. Geological
and hydrogeological studies
conducted in the recent past
have identified the source
rock, and the mineralogy of
the aquifer (groundwater) is
found to be the primary cause
of As toxicity, hence called
geogenic As problem. The
Ganges (G), Brahmaputra (B)
and Meghna (M) rivers flowing
from the Himalayan glaciers
carry massive amounts of rocks
through transportation and
deposit in the middle and lower
plains of India, forming the
largest fluvio-deltaic plain (GBM delta) basin
or Bengal basin. The subsurface sedimentary
rocks of the Bengal plain are composed the early twentieth century from the USA
of Fe-oxy-hydroxide/Al/Mn- oxides, where As (As3+ and As5+, as a crustal element) species adsorb onto the solid phases. These As-laden sediments with local geochemical factors drive the as release from the rock-minerals into the groundwater. It has also been seen that high groundwater abstraction for drinking and irrigation, groundwater flow, recharge–discharge, industrial pollution and agricultural inputs intensify the as problem more in groundwater. Previous studies highlighted some of the considerable facts regarding
By the twentieth to the twenty- first century, 10 districts (114 blocks) of West Bengal, other Indian states (Bihar, Jharkhand, Assam, Uttar Pradesh, etc.) and many South-Eastern Asiatic countries (Bangladesh, Vietnam, Cambodia, China and Thailand) were severely affected by groundwater As contamination (World Health Organization) limit of 5 μg/L As), threatening the lives of millions of people.
as problem, until the microbiological research came into existence. Few of the studies in