5 research outputs found
Pond-Derived Organic Carbon Driving Changes in Arsenic Hazard Found in Asian Groundwaters
Microbially mediated
reductive processes involving the oxidation
of labile organic carbon are widely considered to be critical to the
release of arsenic into shallow groundwaters in South and Southeast
Asia. In areas where there is significant pumping of groundwater for
irrigation the involvement of surface-derived organic carbon drawn
down from ponds into the underlying aquifers has been proposed but
remains highly controversial. Here we present isotopic data from two
sites with contrasting groundwater pumping histories that unequivocally
demonstrate the ingress of surface pond-derived organic carbon into
arsenic-containing groundwaters. We show that pond-derived organic
carbon is transported to depths of up to 50 m even in an arsenic-contaminated
aquifer in Cambodia thought to be minimally disturbed by groundwater
pumping. In contrast, in the extensively exploited groundwaters of
West Bengal, we show that pond-derived organic carbon is transported
in shallow groundwater to greater depths, in excess of 100 m in the
aquifer. Intensive pumping of groundwaters may potentially drive secular
increases in the groundwater arsenic hazard in this region by increasing
the contribution of bioavailable pond-derived dissolved organic carbon
drawn into these aquifer systems and transporting it to greater depths
than would operate under natural flow conditions
Number of rare non-synonymous and splice-site variants found in the 439 sequenced samples.
<p>*Based on our segregation analyses.</p><p>**Not present in the AD&FTD mutation database or in dbSNP.</p><p>Only the rare (MAF<0.05) non-synonymous, splice-site and nonsense sequence variants are shown.</p
Distribution of the families by the number of affected individuals in each family.
<p>The number of families with different numbers of affected individuals is shown. More than 50% of the families have 4 or 5 affected individuals. The number of sequence variants found in each group is also shown.</p