Preliminary trace element analysis of arsenic in Nepalese groundwater may pinpoint its origin

Abstract

Arsenic contamination of groundwater used as drinking water in South Asia poses a serious health threat to the inhabitants living on alluvial plains of the Himalayan foreland of countries like Bangladesh, India, Nepal and Myanmar. Although the geological and geochemical conditions favoring the release of the highly poisonous contaminant from the sediments hosting the groundwater are meanwhile quite well understood, there is still a significant debate about the origin of arsenic. The sediments forming a huge proportion of the Terai (lowlands of Nepal) aquifers are derived from two main sources, (i) sediments deposited by large rivers that erode the upper Himalayan crystalline rocks and (ii) weathered meta-sediments carried by smaller rivers originating in the Siwalik foothills adjacent to the Terai. In this article a so far underestimated source of As is discussed: the peraluminous leucogranites found ubiquitously in the Nepal Himalaya. The relationship between the trace elements analyzed in the groundwater in the Terai and trace elements found in such felsic rocks reflect the origin of the arsenic in the high Himalayas of Nepal. In addition to the high concentration of As, a striking feature is the presence of the lithophile trace elements like Li, B, P, Mn, Br, Sr and U in the groundwater. The mentioned elements point to a felsic initial source like metapelites or leucogranites—all rocks showing a high abundance of especially B, P and As as well as Cd and Pb.

Full text

Vol.:(0123456789)
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Environmental Earth Sciences (2018) 77:35
https://doi.org/10.1007/s12665-017-7154-z
INTERNATIONAL VIEWPOINT ANDNEWS
Preliminary trace element analysis ofarsenic inNepalese groundwater
may pinpoint its origin
BarbaraMueller1
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Abstract
Arsenic contamination of groundwater used as drinking water in South Asia poses a serious health threat to the inhabitants
living on alluvial plains of the Himalayan foreland of countries like Bangladesh, India, Nepal and Myanmar. Although the
geological and geochemical conditions favoring the release of the highly poisonous contaminant from the sediments host-
ing the groundwater are meanwhile quite well understood, there is still a significant debate about the origin of arsenic. The
sediments forming a huge proportion of the Terai (lowlands of Nepal) aquifers are derived from two main sources, (i) sedi-
ments deposited by large rivers that erode the upper Himalayan crystalline rocks and (ii) weathered meta-sediments carried
by smaller rivers originating in the Siwalik foothills adjacent to the Terai. In this article a so far underestimated source of
As is discussed: the peraluminous leucogranites found ubiquitously in the Nepal Himalaya. The relationship between the
trace elements analyzed in the groundwater in the Terai and trace elements found in such felsic rocks reflect the origin of the
arsenic in the high Himalayas of Nepal. In addition to the high concentration of As, a striking feature is the presence of the
lithophile trace elements like Li, B, P, Mn, Br, Sr and U in the groundwater. The mentioned elements point to a felsic initial
source like metapelites or leucogranites—all rocks showing a high abundance of especially B, P and As as well as Cd and Pb.
Keywords Arsenic· Groundwater· Trace Elements· Felsic· Leucogranite· Himalaya
Introduction
Arsenic contamination of groundwater used as drinking
water is meanwhile of major health concern in several coun-
tries of South Asia (Bangladesh, India, Nepal, Myanmar,
China, Vietnam, Cambodia, China). Particularly inhabitants
living on alluvial plains of the Himalayan foreland are in
danger to develop severe signs of a range of adverse health
effects. Arsenic has a clear geogenic source and its elevated
concentrations in natural groundwaters are considered to be
due to natural weathering of the Himalayan belt (Acharyya
etal. 2000; Gurung etal. 2005; Guillot and Charlet 2007;
Guillot etal. 2015; Mueller 2017). The sediments carried
by the Ganga–Brahmaputra river system build up the Hima-
layan foreland basin and the Bengal fan—one of the larg-
est modern fluvial deltas of the world (France-Lanord etal.
1993; Garzanti etal. 2004).
Arsenic is not of high abundance in the Earth’s continen-
tal crust. The ubiquitous mineral pyrite represents the largest
reservoir of As. Beside pyrite, As is mainly concentrated
in hydrous iron oxides and clay minerals. Arsenic can be
easily solubilized in groundwater depending on pH, redox
conditions, temperature, and solution composition. A small
number of source materials are now recognized as signifi-
cant contributors to arsenic in water supplies: organic-rich or
black shales, Holocene alluvial sediments with slow flushing
rates, mineralized and mined areas (most often gold depos-
its), volcanogenic sources, and thermal springs.
There is still an ongoing debate about the initial source
of the arsenic contaminating the groundwater in the allu-
vial plains of Nepal and other countries in South East Asia.
The aim of this study is to relate the trace element contents
of several groundwater samples from Nawalparasi district
(Terai, Nepal) to the trace element contents of the initial
source rocks. These trace elements in groundwater reflect
the origin of the arsenic in the high Himalayas of Nepal.
In the lowland of Nepal (the so called Terai) all four
major Himalayan tectonic units are exposed: (1) the Tethys
Himalaya, delimited at the base by the South Tibetan
* Barbara Mueller
barbara.mueller@erdw.ethz.ch
1 Bamugeobiochem, Horbenstrasse 4, 8356Ettenhausen,
Switzerland

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Detachment system (STDS); (2) the Higher Himalayan
Crystallines (HHC) delimited at the base by the Main
Central Thrust I (MCT I); (3) the Lesser Himalaya (LH)
divided into upper and lower Lesser Himalaya, delimited
at the base by the Main Boundary Thrust (MBT); and (4)
the Siwaliks, delimitated at its base by the Main Fron-
tal Thrust (MFT) and the Quaternary foreland basin. The
Archean crystalline formations deep beneath the Alluvium
of the Terai as well as the marine sedimentary deposits
forming the high Himalayas, and the Siwalik formation
built up by the then east–west flowing rivers can be found
within confined space (Yadav etal. 2015).
These four units span a wide range of various rocks of
metamorphic, sedimentary, and igneous origin, making it
possible for their differential erosion to account for some
of the groundwater arsenic heterogeneity that can be seen
in the foreland and delta (i.e. Gurung etal. 2005; Shah
2008; Geen etal. 2008; Guillot etal. 2015). In the region
of provenance of the Terai sediments, the Tethys Hima-
laya includes 10km of various metasedimentary rocks
(limestones, calc-schists, shales, quartzites) ranging from
Cambrian to Jurassic. Leucogranites like the Manaslu
leucogranite are also found emplaced within the Tethyan
rocks (e.g. Guillot and Le Fort 1995).
The geology of the Terai region of Nepal itself is on
the whole comparable to the Bengal Delta Plain and it
is the continuation of Indo-Gangetic trough. The Terai
Plain is an active foreland basin consisting of Quaternary
sediments that include molasse units consisting of gravel,
sand, silt, and clay. Most of the rivers in the Terai flow
from north to south. All major rivers originate in the high
Himalayas, whereas minor rivers also emanate from the
nearby Siwalik Hills, and therefore deposit sediments in
the form of a fan along the flank of the Terai basin. Fine
sediments and organic material are deposited in inter-fan
lowlands, in wetlands and swamps (Sharma 1995; Kansa-
kar 2004; Yadav etal. 2011).
Nawalparasi is the most intensively studied Terai prov-
ince concerning arsenic-contaminated groundwater in
Nepal. The lithology of the Nawalparasi province sedi-
mentary basin belongs to Holocene alluvium including
the present-day alluvial deposits, channel sand and gravel
deposits as well as outwash deposits (Yadav etal. 2014).
One major river, the Narayani/Gandaki, which originates
in the Higher Himalaya, flows along the eastern boundary
of the Nawalparasi district and has had a major influence
on the underlying unconsolidated Holocene fluvial depos-
its that comprise the floodplain aquifer system. Unlike
other regions of Terai, where finer sediments typically
increase toward the south, fines predominate in the north
and sand and gravels are found near the Nepal–India bor-
der (Shrestha etal. 2004). In the areas with fine-grained
sediments, elevated concentrations of As are typically
recorded (Brikowski etal. 2004a, b; Diwakar etal. 2015).
Using trace element analysis
The initiative for groundwater sampling was first taken by
CAWST (Centre for Affordable Water Sanitation Technol-
ogy) Calgary, Canada, in cooperation with Eawag (Swiss
Federal Institute for Environmental Science and Technol-
ogy), Dübendorf, Switzerland. Co-workers from CAWST
and ENPHO (Environment & Public Health Organization)
Kathmandu, Nepal, installed iron-assisted bio-sand filters
constructed on the basis of arsenic removal from water
using zero-valent iron (ZVI) media from the early 1990s.
The modified model now used in Nepal is known as the Kan-
chan filter (Ngai etal. 2006, 2007). As stated by Singh etal.
(2014) and CAWST, the efficacy of Kanchan filters under
field conditions operating for a long period has scarcely
been observed. Due to the growing concern that some of
the Kanchan filters still had effluent arsenic concentrations
exceeding the Nepal drinking water quality standard value
(50μg/l), a field campaign aiming to collect groundwater,
intermittently filtered and effluent water, inspect the filters
at household levels and analyse these samples for trace ele-
ments was organized in October 2015 (post-monsoon). A
second field campaign was arranged in the pre-monsoon
period (April 2017) in order to detect for differences in
arsenic concentration in the groundwater between the two
seasons. Measurements to improve the efficiency of the fil-
ters are under progress.
Ten water samples from Nawalparasi district were col-
lected from hand pumps in April 2017 for the analysis of a
wide range of trace elements. The pumps were all operated
before sample collection to remove all standing water in the
tube wells. Households for sample collections were chosen
according a register provided by ENPHO with filtered water
exceeding the Nepal drinking water quality standard value
(50μg/L). Sample locations include groundwater from pri-
vate tube wells found within the municipalities of Ramgram
(formerly Parasi, the capital of the Nawalparasi district),
Manari and Panchanagar (within proximity of Ramgram).
Water samples were acidified with HNO3 and sent to the
laboratory in Switzerland for further examination.
All trace elements in the groundwater samples were
determined by ICP-MS (Agilent Technology, 7500 Series,
Agilent Technologies, Waldbronn, Germany) at Eawag,
Dübendorf, Switzerland, after 1:2 dilution with 0.5 M
HNO3. Each measurement was conducted in triplicate. All
ICP-MS determinations agreed to within 3–5% standard
deviation (Wenk etal. 2014).
Average geochemical compositions (major and trace ele-
ments) of 10 groundwater samples of Nawalparasi boreholes

Environmental Earth Sciences (2018) 77:35
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Page 3 of 6 35
are reported in Table1. Lithium, B, P, V, Cr, Mn, Fe, Cu, Zn,
Se, Br, Sr, Mo, Cd, P and U are among the most prominent
main and trace elements beside arsenic and could be found in
relevant concentrations. The average content of arsenic was
0.25ppm (226.97µg/l), the range of arsenic concentration
in the water samples varied between 0.04ppm (41.04µg/l)
and 0.75ppm (745.2µg/l) with most data well above the
Nepal drinking water quality standard value (50μg/l). The
average concentration of Fe present is rather low (1.30mg/l).
The anion S was hardly detectable—in only 3 samples a
significant concentration was detected.
Initial source ofthetrace elements
ingroundwater
A striking feature besides the high concentration of As is the
presence of the lithophile trace elements like Li, B, P, Mn,
Br, Sr and U. But also Fe exhibits a significant concentration
in groundwater, while Cu, Zn, Mo, Cd and Pb could be found
in minor concentrations. Boron drew inasmuch the attention
immediately, as it is very rarely found in significant amounts
in common minerals like silicates. Tourmaline is one of the
very few minerals incorporating a significant portion of
boron in its structure. As already mentioned by Yousafzai
etal. (2010), boron in springwaters in the Peshawar basin
and surroundings in the Himalayan foreland of Pakistan is
closely associated with igneous complexes (most probably
with the tourmaline-rich Tertiary leucogranites). Boron is
well known to be an ubiquitous constituent of groundwater
e.g. in Bangladesh, Vietnam or Greece. The average con-
centration of boron in the 10 groundwater samples from the
Nepalese Terai is 56.92µg/l, the maximum concentration
of boron in Bangladesh is as high a 2.1mg/l and has been
ascribed to the presence of residual salt water in the aqui-
fers (Ravenscroft and McArthur 2008). Concentrations of
boron in Vietnam increase from <50µg/l inland to 260
to 2100µg/l towards the seashore (Winkel etal. 2011). In
Greece, boron was detected at concentrations above 1mg/L.
The high boron concentrations were detected only in the
groundwaters of the Kalikratia area and it was believed that
boron contamination was caused by the mixing of ground-
waters with underlying thermal waters rich in boron, which
are often found in the area (Katsoyiannis etal. 2007). As
Nepal presents a landlocked country having no link to the
ocean, an influence of salt water can be excluded. In the
Himalayas of Nepal some thermal springs can be found
but their influence is considered to be marginal taking the
widespread occurrence of Tertiary leucogranites besides
metapelites and black shales into account. Consistently Rai
(2003) reports about elevated boron in metasedimentary
rocks of the lesser Himalaya (up to 322ppm) and as well in
the Manaslu leucogranite (up to 950ppm) in which tourma-
line represents the boron-containing mineral. Stueben etal.
(2003) report about tourmaline-containing aquifers enriched
in As in West Bengal, India and concludes that the heavy
mineral assemblage of the these aquifers (opaque minerals,
garnet, tourmaline, kyanite, rutile, zircon) indicate a mixed
metamorphic and igneous provenance for the eroded and
deposited materials.
The anion S was hardly detectable. Despite this fact, some
authors like Acharyya etal. (1999) suggested an oxidation
of pyrite in the sediments that would lead to an increased
concentration of SO4 in the groundwater. This mechanism
can be clearly ruled out. Even pyrite oxidation is unlikely
to be a major source of arsenic to anoxic water, which is
a prevalent type beneath the southern lowlands of Nepal;
ophiolites were seen as the initial source of arsenic con-
tained in arsenopyrite (e.g. Stanger 2005; Guillot and Char-
let 2007). However, ophiolites do not exist in the Nepalese
Himalaya. In addition, Berg etal. (2008) report about an
average molar Fe/As ratio between 60 and 68 in arsenic-
contaminated groundwater in the Hanoi area of Vietnam.
The average molar Fe/As ratio from the samples of this study
adds up to 7.7. This ratio and the low value of Fe is another
good indicator for sediments representing a heterogenous
mixture of parent rocks of felsic origin (Gurung etal. 2005;
Guillot etal. 2015; Verma etal. 2016).
Figure1 shows the most prominent trace elements in
groundwater from Nawalparasi district compared with the
few available data of the Macusani obsidian glass (peralu-
minous in composition, enriched in As-B-F-P). The data for
comparison are taken from Borisova etal. (2010). In this
article Borisova etal. (2010) were the first to report about
a significant enrichment of arsenic in a peraluminous glass
from Macusani (SE Peru) that is representative of anatectic
Table 1 Average major and trace element concentrations in 10 groundwater samples from Nawalparasi district, Terai, Nepal. Standard deviation
3–5% (Wenk etal. 2014)
Only a limited number of analyses were feasible for S (3 samples). Therefore these results are not included in the table. All other elements ana-
lyzed were below LOD
Average Li (µg/l) B (µg/l) Na (mg/l) Mg (mg/l) Al (µg/l) Si (mg/l) P (mg/l) Cl (mg/l) K (mg/l) Ca (mg/l) V (µg/l) Cr (µg/l)
4.45 56.92 45.98 23.47 5.63 14.13 0.12 10.83 1.28 88.73 0.07 0.13
Average Mn (mg/l) Fe (mg/l) Cu (µg/l) Zn (µg/l) As (µg/l) Se (µg/l) Br (µg/l) Sr (µg/l) Mo (µg/l) Cd (µg/l) Pb (µg/l) U (µg/l)
0.06 1.34 0.38 10.12 226.97 0.01 0.04 453.80 7.44 0.02 0.07 0.06

Environmental Earth Sciences (2018) 77:35
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35 Page 4 of 6
melts derived from metasedimentary crustal protoliths. The
glass used by Borisova etal. (2010) showed enrichments,
by factors of 10 to 100, in comparison with the mean con-
tinental crust values, for As and other incompatible trace
elements (e.g., Be, B, Rb, Sn, Sb, and Ta), and by factors
of 100 to 200 for Li, Cd, and Cs. Moreover, Borisova etal.
(2010) report about arsenic being present in the peralumi-
nous glass in trivalent state in the form of oxy-hydroxide
complexes like AsO(OH)2
− and/or As(OH)3, similar to those
dominant in the aqueous fluid vapor phases at hydrothermal-
magmatic conditions. The depolymerized melt structure
caused by elevated H2O, F, and P contents would likely to
allow accommodation of high concentrations of metalloid
hydroxide/hydrated complexes. Thus, these melts may be
highly enriched in volatile and incompatible elements hav-
ing similar structures and affinities for water and hydroxide
ligands. Such enrichment is likely to occur by the presence
of large concentrations of the volatile components like B,
F, P, and H2O.
In another article Borisova etal. (2012) report about Cd
(up to~300ppm) found in quartz-hosted fluid and melt
inclusions in hydrous peraluminous systems (pegmatites
and leucogranites) for the first time. Some of the ground-
water samples in Nawalparasi show detectable concentra-
tions of Cd. In a fluid inclusion study of the Huanuni tin
deposit in Bolivia (hosted in peralumious granites with
ASI≥1.1), Mueller etal. (2001) detected Li, B, Zn, As
and Pb in quartz-hosted inclusions. The indicative trace ele-
ments in leucogranites (Li, B, P, Mn, Zn, As, Sr, Pb, U) are
similarly detected in the groundwater in Nawalparasi. The
high concentration of Sr in groundwater can be explained by
frequent occurrence of calcium carbonates in the soil hosting
the groundwater.
Low-grade metapelites are often considered as proto-
liths of peraluminous granites [see e.g. Guillot and Le Fort
(1995), Godin etal. (2006), Searle etal. (2016)] and in turn
demonstrate concentrations of As, Sb, Be, B, Ba and Rb by
a factor of 5 to 10 higher than their average crustal abun-
dances [2–5ppm, Onishi and Sandel (1955); Turekian and
Wedepohl (1961); Rudnick and Gao (2003)]. Therefore, such
enrichments allow the use of arsenic as a geochemical tracer
of subduction-zone and collision-zone environments (Bori-
sova etal., 2010). The leucogranites found in the Himalayas
of Nepal are clearly peraluminous in composition [see e.g.
Guillot and Le Fort (1995); Guo and Wilson (2012); Carosi
etal. (2013)] and therefore a comparison with the findings
from Borisova etal. (2010) is clearly warranted. Most of the
leucogranites analyzed by Guo and Wilson (2012) are per-
aluminous (ASI>1) to strongly peraluminous (ASI≥1.1).
According to Finger and Schiller (2012), lead is one of
the few elements that behave generally incompatibly dur-
ing crustal melting. Pb can become significantly enriched in
low-T S-type granite melts, particularly if the proportion of
partial melting remains low. In addition, muscovite, a major
constituent of metapelitic sources, can accumulate relatively
high Pb contents. The leucogranites in the Nepal Himala-
yas are therefore considered to be of crustal origin and are
formed from vapour-absent muscovite-dehydration melting
of pelitic and psammitic protoliths during the Late Miocene
(see e.g. Deniel etal. 1987; Inger and Harris 1993; Ayres
and Harris 1997; Streule etal. 2010; Rubatto etal. 2013;
Bikramaditya Singh 2013; Searle etal. 2016).
This study links the detected trace elements of groundwa-
ter samples from the lowlands in Nepal to known trace ele-
ments contained in peraluminous obsidian glasses from Peru
enriched in As-B-F-P. Significant enrichments of arsenic in
these peraluminous glasses are representative of anatectic
melts derived from metasedimentary crustal protoliths. The
peraluminous leucogranites of the high Nepal Himalayas
are also reported being derived from such crustal protoliths.
As a consequence, trace elements including As reported to
be found in peraluminous glasses and melts turn up again
in the groundwater in the Terai of Nepal. They have been
deposited as sediments by large rivers that erode the upper
Himalayan crystalline rocks containing minerals exhibiting
elevated As concentrations.
The help and analytical skills of Dr. Stephan Hug, Eawag,
Dübendorf, Switzerland greatly contributed to this work.
Preparations for fieldwork and assistance in the field were
possible through the support of Tommy Ngai and Candice
Young-Rojanschi (CAWST, Calgary, Canada), Bipin Dan-
gol and Hari Boudhatoki (ENPHO, Kathmandu, Nepal), and
Gyan Prakash Yadav (Parasi, Nepal). Special thanks go to
Shankar Rai and Som Rai, my loyal expedition and trekking
guides in Nepal who were responsible for the logistics over
many years.
Fig. 1 The most noticeable trace elements in groundwater from
Nawalparasi district (blue squares) compared with the few available
data of the Macusani obsidian glass (peraluminous in composition,
enriched in As-B-F-P). The data for comparison (red circles) are
taken from Borisova etal. (2010). Note the logarithmic scale for com-
parison of concentrations

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Page 5 of 6 35
References
Acharyya SK, Chakraborty P, Lahiri S, Raymahashay BC, Guha S,
Bhowmik A (1999) Arsenic poisoning in the Ganges delta. Nature
401:545–547
Acharyya SK, Lahiri S, Raymahashay BC, Bhowmik A (2000) Arsenic
toxicity of groundwater in parts of the Bengal basin in India and
Bangladesh: the role of Quaternary stratigraphy and Holocene
sea-level fluctuation. Environ Geol 39:1127–1137
Ayres M, Harris N (1997) REE fractionation and Nd–isotope disequi-
librium during crustal anatexis: constraints from Himalayan leu-
cogranites. Chem Geol 139:249–269
Berg M, Trang PTK, Stengel C, Buschmann J, Viet PH, Dan NV,
Giger W, Stüben D (2008) Hydrological and sedimentary con-
trols leading to arsenic contamination of groundwater in the hanoi
area, vietnam: the impact of iron–arsenic ratios, peat, river bank
deposits, and excessive groundwater abstraction. Chem Geol
249:91–112
Bikramaditya Singh RK (2013) Origin and emplacement of the higher
himalayan leucogranite in the eastern himalaya: constraints from
geochemistry and mineral chemistry. J Geol Soc India 81:791–803
Borisova AY, Pokrovski GS, Pichavant M, Freydier R, Candaudap
F (2010) Arsenic enrichment in hydrous peraluminous melts:
insights from femtosecond laser ablation-inductively coupled
plasma-quadrupole mass spectrometry, and insitu X-ray absorp-
tion fine structure spectroscopy. Am Miner 95:1095–1104
Borisova AY, Thomas R, Salvi S, Candaudap F, Lanzanova A, Chmel-
eff J (2012) Tin and associated metal and metalloid geochemistry
by femtosecond LA-ICP-QMS microanalysis of pegmatite– leu-
cogranite melt and fluid inclusions: new evidence for melt–melt–
fluid immiscibility. Miner Mag 76:91–113
Brikowski TH, Smith LS, Shei TC, Shrestha SD (2004) Correlation
of electrical resistivity and groundwater arsenic concentration,
Nawalparasi, Nepal. J Nepal Geol Soc 30:99–106
Brikowski TH, Neku A, Shrestha SD, Smith LS (2014) Hydrologic
control of temporal variability in groundwater arsenic on the Gan-
ges floodplain of Nepal. J Hydrol 518:342–353
Carosi R, Montomoli C, Rubatto D, Visona D (2013) Leucogranite
intruding the South Tibetan detachment in western Nepal: impli-
cations for exhumation models in the Himalayas. Terra Nova
25:478–489
Deniel C, Vidal P, Fernandez A, Le Fort P, Peucat JJ (1987) Isotopic
study fo the Manaslu granite (Himalaya, Nepal): inferences on
the age and source of Himalayan leucogranites. Contrib Mineral
Petrol 96:78–92
Diwakar J, Johnston SG, Burton ED, Shrestha SD (2015) Arsenic
mobilization in an alluvial aquifer of the Terai region, Nepal. J
Hydrol Reg Stud 4:59–79
Finger F, Schiller D (2012) Lead contents of S-type granites and their
petrogenetic significance. Contrib Miner Petrol 64:747–755
France-Lanord C, Derry LMichard A (1993) Evolution of the Himalaya
since Miocene time: isotopic and sedimentologic evidence from
the Bengal fan. In: Treloar PJ, Searle MP (eds) Himalayan tecton-
ics, vol 74. Geol Soc Spec Pub, London, pp 445–465
Garzanti E, Vezzoli G, Ando S, France-Lanord C, Singh SK, Foster G
(2004) Sand Petrology and focused erosion in collision orogens:
the Brahmaputra case. Earth Planet Sci Lett 220:157–174
Godin L, Grujic D, Law RD, Searle MP (2006) Channel flow, duc-
tile extrusion and exhumation in continental collision zones: an
introduction. In: Law RD, Searle MP, Godin L (eds) Channel
Flow, Ductile Extrusion and Exhumation in Continental Collision
Zones, vol 268. Geol Soc Spec Pub, London, pp 1–23
Guillot S, Charlet L (2007) Bengal arsenic, an archive of Hima-
laya orogeny and paleohydrology. J Environ Sci Health A
42:1785–1794
Guillot S, Le Fort P (1995) Geochemical constraints on the bimodal
origin of high himalayan leucogranites. Lithos 35:221–234
Guillot S, Garçon M, Weinman B, Gajurel A, Tisserand D, France-
Lanord C, van Geen A, Chakraborty S, Huyghe P, Upreti BN,
Charlet L (2015) Origin of arsenic in Late Pleistocene to Holo-
cene sediments in the Nawalparasi district (Terai, Nepal). Envi-
ron Earth Sci. http s://doi.org/10.1007 /s126 65-015-4277 -y
Guo Z, Wilson M (2012) The Himalayan leucogranites: constraints
on the nature of their crustal source region and geodynamic
setting. Gondwana Res 22:360–376
Gurung JK, Ishiga H, Khadka M (2005) Geological and geochemi-
cal examination of arsenic contamination in groundwater in the
Holocene Terai Basin, Nepal. Environ Geol 49:98–113
Inger S, Harris N (1993) Geochemical constraints on leucogranite
magmatism in the Langtang Valley, Nepal Himalaya. J Petrol
34:345–368
Kansakar DR (2004) Geologic and geomorphologic characteristics
of arsenic contaminated groundwater area in Terai, Nepal. In:
Arsenic testing and finalization of groundwater legislation pro-
ject, summary project report. In: D. R. Department of Irrigation,
Lalitpur, Nepal, HMG/Nepal, pp 85–96
Katsoyiannis IA, Hug SJ, Ammann A, Zikoudi A, Hatziliontos C
(2007) Arsenic speciation and uranium concentrations in drink-
ing water supply wells in Northern Greece: correlations with
redox indicative parameters and implications for groundwater
treatment. Sci Total Environ 383:128–140
Mueller B (2017) Arsenic in groundwater in the southern lowlands
of Nepal and its mitigation options: a review. Environ Rev
25:296–305
Mueller B, Frischknecht R, Seward TM, Heinrich CA, Camargo
Gallegos W (2001) A fluid inclusion study of the Huanuni tin
deposit Bolivia: some insights with LA-ICP-MS analysis. Miner
Deposita 36:680–688
Ngai TKK, Murcott SE, Shrestha RR, Dangol B, Maharjan M (2006)
Development and dissemination of Kanchan™ arsenic filter in
rural Nepal. Water Sci Technol 6:137–146
Ngai TKK, Shrestha RR, Dangol B, Maharjan M, Murcott SE (2007)
Design for sustainable development–Household drinking water
filter for arsenic and pathogen treatment in Nepal. J Environ
Sci Health—A Tox Hazard Subst Environ Eng 42:1879–1888
Onishi H, Sandell EB (1955) Geochemistry of arsenic. Geochim
Cosmochim Acta 7:1–33
Rai SM (2003) Distribution of boron in the rocks of central Nepal
Himalaya. J Nepal Geol Soc 28:57–62
Ravenscroft P, McArthur JM (2008) Mechanism of regional enrich-
ment of groundwater by boron: the examples of Bangladesh and
Michigan, USA. Appl Geochem 19:1413–1430
Rubatto D, Chakraborty S, Dasgupta S (2013) Timescales of crustal
melting in the Higher Himalayan Crystallines (Sikkim, Eastern
Himalaya) inferred from trace element-constrained monazite
and zircon chronology. Contrib Miner Petrol 165:349–372
Rudnick RL, Gao S (2003) Composition of the continental crust. In:
Holland HD, Turekian KK (eds) Treatise on Geochemistry, vol
3. Elsevier, Amsterdam, pp 1–64
Searle MP, Avouac JP, Elliott J, Dyck JE (2016) Ductile shearing
to brittle thrusting along the Nepal Himalaya: linking Miocene
channel flow and critical wedge tectonics to 25th April 2015
Gorkha earthquake. Tectonophysics. http s://doi.org/10.1016
/j.tect o.2016 .08.003
Shah BA (2008) Role of Quaternary stratigraphy on arsenic–con-
taminated groundwater from parts of Middle Ganga Plain, UP–
Bihar, India. Environ Geol 53:1553–1561
Sharma CK (1995) Shallow (phreatic) aquifers of Nepal, 1st edn.
Sangeeta Publishing Kathmandu, Nepal

Environmental Earth Sciences (2018) 77:35
1 3
35 Page 6 of 6
Shrestha SD, Brikowski T, Smith L, Shei TC (2004) Grain size con-
straints on arsenic concentration in shallow wells of Nawalparasi,
Nepal. J Nepal Geol Soc 30:93–98
Singh A, Smith LS, Shrestha S, Maden N (2014) Efficacy of arse-
nic filtration by Kanchan Arsenic Filter in Nepal. J Water Health
12:596–599
Stanger G (2005) A palaeo-hydrogeological model for arsenic con-
tamination in southern and south-east Asia. Environ Geochem
Health 27:59–367
Streule MJ, Searle MP, Waters DJ, Horstwood MSA (2010) Meta-
morphism, melting, and channel flow in the Greater Himalayan
Sequence and Makalu leucogranite: constraints from thermo-
barometry, metamorphic modeling, and U-Pb geochronology.
Tectonics. http s://doi.org/10.1029 /2009 TC00 2533
Stueben D, Berner Z, Chandrasekharam D, Karma J (2003) Arsenic
enrichment in groundwater of West Bengal, India: geochemical
evidence for mobilization of under reducing conditions. Appl
Geochem 18:1417–1434
Turekian KK, Wedepohl KH (1961) Distribution of the elements
in some major units of the earth’s crust. Geol Soc Amer Bull
72:175–192
van Geen A, Radloff K, Aziz Z, Cheng Z, Huq MR, Ahmed KM,
Weinman B, Goodbred S, Jung HB, Zheng Y, Berg M, Trang
PTK, Charlet L, Metral J, Tisserand D, Guillot S, Chakraborty P,
Gajurel AP, Upreti BN (2008) Comparison of arsenic concentra-
tions in simultaneously-collected groundwater and aquifer parti-
cles from Bangladesh, India, Vietnam and Nepal. Appl Geochem
23:3244–3251
Verma S, Mukherjee A, Choudhury R, Mahanta C (2016) Brahmaputra
river basin groundwater: solute distribution, chemical evolution
and arsenic occurrences in different geomorphic settings. J Hydrol
Reg Stud 4:131–153
Wenk C, Kaegi R, Hug SJ (2014) Factors affecting arsenic and uranium
removal with zero-valent iron: laboratory tests with Kanchan-type
iron nail filter columns with different groundwaters. Environ
Chem 11:547–557
Winkel L, Trang PTK, Lan VM, Stengel C, Amini M, Ha NT, Viet
PH, Berg M (2011) Arsenic pollution of groundwater in Vietnam
exacerbated by deep aquifer exploitation for more than a century.
PNAS 108(4):1246–1251
Yadav IC, Dhuldhaj UP, Mohan D, Singh S (2011) Current status of
groundwater arsenic and its impacts on health and mitigation
measures in the Terai basin of Nepal: an overview. Environ Rev
19:55–67
Yadav IC, Devi NL, Sing (2014) Spatial and temporal variation in arse-
nic in the groundwater of upstream of Ganges River Basin. Envi-
ron Earth Sci, Nepal. http s://doi.org/10.1007 /s126 65-014-3480 -6
Yadav IC, Devi NL, Sing S (2015) Reductive dissolution of iron-oxyhy-
droxides directs groundwater arsenic mobilization in the upstream
of Ganges River basin, Nepal. J Geochem Explor 148:150–160
Yousafzai A, Eckstein Y, Dahl PS (2010) Hydrochemical signatures of
deep groundwater circulation in a part of the Himalayan foreland
basin. Environ Earth Sci 59:1079–1098