Decadal Variation In The Major Ion Chemistry Biology Essay
Glaciers, while normally regarded as sensitive indexs of clime alteration, can besides be affected by assorted factors like atmospheric deposition. Study of major ions ( Mg2+ , Ca2+ , Na+ , K+ , HCO3- , SO42- and Cl- ) of meltwater run outing from Chhota Shigri glacier was carried out to understand weathering and geochemical procedures commanding the major ion chemical science of the glacier meltwater. Chhota Shigri glacier meltwater was sampled in August 2008. Mg2+ is the dominant cation followed by Ca2+ , K+ and Na+ .
Whereas HCO3- is the dominant anion followed by SO42- and Cl- . The high ratio of Ca+Mg/TZ+ i.e. 0.77 and low ratio of Na+K/TZ+ i.e. 0.
23 shows that carbonate weathering is the dominant mechanism commanding major ion chemical science followed by silicate weathering in the survey country. In this paper we aim to measure the possible consequence of assorted procedures that affect the chemical science of meltwater of Chhota Shigri glacier.Decadal fluctuation in the major ion chemical science of Chhota Shigri glacier meltwater was carried out by comparing the hydrochemistry of August 2008 with old survey carried out in 1987. Comparison between the two informations sets shows that cations like Ca2+ increased about 6 times, Mg2+ 87 times, Na+ 10 times and K+ 19 times, while anions like Cl- increased about 12 times, HCO3- 85 times and SO42- 49 times between 1987 and 2008.
This could be attributed to increased weathering rates due to climate heating, atmospheric deposition or a combination of both. Annual specific mass balance of Chhota Shigri glacier was frequently aggressively negative during 2002 to 2010, indicating to glacier recession, which may be besides attributed to planetary climatic alteration.
Temporal fluctuation, Major ion chemical science, Mass balance, Weathering, Chhota Shigri glacier, Atmospheric deposition
The Himalayas are normally referred to as “ the residence of ageless snow ” being the largest depot of snow and ice outside the polar part [ 1 ] .
Indus, Ganga and Brahmaputra basins put together have 32392 glaciers busying 71182.08 Km2 of glaciated country [ 2 ] . Assorted surveies of glaciers in Himalaya such as Ahmad and Hasnain [ 3 ] , Kumar et Al.
[ 4 ] and in Alpine part by Rainwater and Guy [ 5 ] , Beherens et Al. [ 6 ] , Lorrain and Souchez [ 7 ] , Collins [ 8 ] , Tranter and Raiswell [ 9 ] have suggested that the principal flow constituent of meltwater coming out of the glacier end point passes through the subglacial environment. These surveies indicate that rate of chemical weathering is high in glaciated catchments ensuing from long abode times of meltwater in contact with the bed stone. Hydrochemistry of glacier evolves from precipitation ( rainfall and snow ) and gets enriched during the crossbeam through sub-glacial channels and stone ice interface [ 10 ] .Conceptual commixture theoretical accounts have produced by clip series analysis of fluctuations in dissolved ion concentrations of meltwaters run outing from neb of glacier, which elucidate hydrological features of glacier on seasonal and diurnal graduated tables ( Tranter et al 1993, Theakston and Knudsen 1996 a, B, Fairchild et al 1999a, Yde and Knudsen 2004 ) . Assorted hydrochemical surveies on Alpine glaciers carried out by Tranter et al 1993, Rainwater and Guy 1961, Brown et al 1996a, B and in Himalayan glaciers by Hasnain et al 1989, Dhanpal 1990, Singh et al 1998, Ahmad and Hasnain 2000, 2001, Kumar et Al. 2009 and Singh et Al.
2012 indicate that by and large calcium is the dominant cation in glacier meltwater with lesser concentrations of Mg, K and Na. Whereas hydrogen carbonate and sulfate are dominant anions with changing proportions. Hydrogeochemical word picture of meltwater run outing from glacier helps in placing the nature and concentration of solute embedded in the implicit in bedrock and part from atmospheric deposition. In glacierised countries, solute acquisition procedures vary in infinite and clip. Hence, long-run monitoring of hydrochemical survey helps to quantify the comparative parts of natural and anthropogenetic components in glacier ice melt overflow ( Ramanathan 2011 ) .The morphology, bedrock topography, meteoric and hydrogeochemical parametric quantities every bit good as kineticss of Chhota Shigri glacier have been studied by assorted writers [ 11-15 ] . Chandra river, one of the of import beginnings of H2O for Himachal Pradesh is fed by several glaciers including Chhota Shigri glacier. Information on mass balance and chemical science of meltwater of Chhota Shigri glacier is unequal, and needs to be substantiated by comprehensive surveies.
First clip mass balance in Indian Himalayan glaciers were started by Geological Survey of India on Gara glacier ( Himachal Pradesh ) in 1974 ( Raina et al 1977 ) . In Himachal Pradesh, Gor-Garang glacier during the period 1976-1985 and Shaune Garang glacier during the period 1984-1989 showed negative mass balance of -0.572 thousand w.e.a-1 ( Shankar 2001 ) and -0.
407 m w.e.a-1 ( Singh and Sangewar 1989 ) , severally. Whereas in Uttarakhand, Tipra Bamak glacier during the period 1981-1988, Dunagri glacier during the period 1984-1990 and Dokriani glacier during the period 1993-2000 besides experient negative mass balance of -0.241 thousand w.e.
a-1 ( Gautam and Mukherjee 1989 ) , -1.038 m w.e.a-1 ( Srivastava and Swaroop 1989 ) and -0.320 m w.e.
a-1 ( Dobhal et al 2008 ) , severally. Mass balance measuring and accretion appraisals of Chhota Shigri glacier were carried out during 1987-89 [ 13, 15, 16 ] . Keeping these facts in head this paper aims to turn to the decadal fluctuation in the hydrogeochemical procedures and their possible consequence on the long-run alterations in the chemical science of meltwater of Chhota Shigri glacier.
Area of survey
Geographically Chhota-Shigri glacier is located between 32a?? 11/-32a?? 17/ N and 77a?? 29/- 77a?? 33/ Tocopherol and is a valley type glacier.
It lies on the northern ridge of the Pir Panjal scope in the Lahaul-Spiti vale of Himachal Pradesh, India, in the western Himalaya. This glacier is oriented approximately north-south in its extirpation country, and has a assortment of orientations in the accretion country. Table 1 gives the geographical and topographical features of Chhota Shigri glacier [ 17 ] . The meltwater watercourse from Chhota Shigri glacier flows in a NW way and meets Chandra river at right angles at about 2.5 kilometers downstream of the neb.
Geology of country
Chhota Shigri glacier lies within the Central Crystallines of the Pir Panjal scope of the Himachal Himalaya. Meso- to ketazonal metamorphites, migmatites and gneisses are found here [ 14 ] . The chief lithologic unit of the Chhota Shigri glacier catchment is Rohtang gneiss [ 18 ] , while 3 kilometers upstream of Chhota Dara, in the upper Chandra vale, older Palaeozoic flinty stones are exposed.
The Haimanta formation overlies these within a tectonic interruption, where black slates, phyllites and powdered biotite schists are exposed [ 14 ] . The stones found between Chhota Shigri and Bara Shigri glaciers are granite, granite gneiss, augen gneiss, porphyritic granite, schistose gneiss, milky-white muscovite-quartzite and muscovite-biotite schist. Late phase pegmatitic venas are rather common in which light gray-green felspar crystals are found [ 18 ] .
Climatic records of glacier basins are extremely imperative to understand glacier-climate relationship. Climate of Chhota Shigri glacier is typical of monsoon-arid passage zone where both the winter mid-latitude westerlies ( January-April ) and summer Asian monsoon ( July-September ) influence the climatic status of this glacier ( Wagnon et al 2007 ) . Very few meteoric surveies are carried out on Chhota Shigri glacier, largely of really short period of clip. Highest maximal temperature observed on glacier surface is about 10.
5°C, 11°C, 8.1°C, 7.5°C, 9.
64 °C and 11.85°C and lowest minimal temperature of about -4.5 °C, -1.
3°C, -5.2°C, -1.6°C, -6.22°C and -13.64°C in 18 August-8 September 1986, 18 July -17 August 1987, 2 August – 5 September 1988, 17 August-11 September 1989, 2-8 October 2003 and 18 August- 10 October 2009 severally ( Rizvi 1987, IMD 1987, Apte et al 1988, Kulandivelu et al 1988, Upadhyay et al 1989, Sharma 2007, JNU-IFCPAR 2009 ) .Total rainfall during the thaw season June, July, August and September 2010 is recorded as 25.
5, 122.5, 22.0 and 161.
0 millimeter severally ( Singh 2011 ) . During the summer season in most of the yearss average environmental oversight rate on Chhota Shigri glacier remained pseudo-adiabatic and varied from 0.38 to 0.67°C/100m ( Bhutiyani and Sharma 1989 ) .
Materials and Methods
Meltwater samples ( n=15 ) were collected from Chhota Shigri glacier during 1-15 August 2008. Electrical conduction ( EC ) and pH were measured utilizing portable multi-parameter metre ( HACH-Sension156 ) . Suspended deposits were separated from the H2O samples in the research lab by utilizing 0.45 micrometer millipore membrane filters of 47mm diameter.
Vacuum pump was used to speed up the filtration. Bicarbonate was determined by following potentiometric titration method [ 19 ] . Chloride ion concentration was measured by the quicksilver ( II ) thiocynate method ; Sulphate concentration was measured by turbidimetric method [ 19 ] . Major cations ( Na+ , K+ , Ca2+ and Mg2+ ) were determined by atomic soaking up spectrophotometer ( Shimadzu-AA-6800 ) . Na+ and K+ were analysed in the emanation manner and Ca2+ and Mg2+ in the optical density manner. The analytical preciseness for the analysis of dissolved ions was better than A±5 % .
Mili-Q H2O was used for all analyses. The meltwater trying site was located at 32a?? 17/24.58// N and 77a?? 31/55.21// Tocopherol on the Chhota Shigri glacier watercourse at about 3900 m a.s.l.
, 2.0 kilometer downstream from the neb of Chhota Shigri glacier ( Fig.1 ) .
Consequences and Discussion
The major ion composings of meltwater run outing from Choota Shigri glacier during August 2008 is given in Table 2.
The mean pH and EC values of the Chhota Shigri glacier meltwater were found as 7.4 ( 6.7-7.8 ) and 15.3 Aµs/cm ( 10.
0-30.0 Aµs/cm ) , severally. HCO3- is the dominant anion followed by SO42- and Cl- . HCO3- concentration ranges from 4.
48-24.0 mg/l with an mean value of 10.9 mg/l. Whereas SO42- and Cl- concentration varies from 2.40-5.
17 mg/l with an mean value 3.43 mg/l and 0.27-0.
77 mg/l with an mean value of 0.51 mg/l, severally. Mg2+ is the dominant cation and its concentration varies from 0.65-1.33 mg/l with an mean value of 0.96 mg/l. Whereas the mean concentration of Ca2+ , K+ and Na+ are found as 0.
72 mg/l ( 0.54-0.94 mg/l ) , 0.62 mg/l ( 0.
53-0.73 mg/l ) and 0.45 mg/l ( 0.
16-0.59 mg/l ) , severally. TDS value of Chhota Shigri glacier meltwater varies from 11.3-33.3 mg/l with an mean value of 20.2 mg/l.
Meltwaters run outing through subglacial channels become chemically enriched by interacting with basal moranic stuffs ( Bezinge et al. 1973 ) . The ( Ca+Mg ) vs entire cations spread secret plan ( Fig. 2 ) shows that all points fall above 1:1 line with an mean tantamount ratio of 0.77 ( 0.
73-0.83 ) . This shows that carbonate weathering is the dominant mechanism commanding chemical composing of meltwater run outing from Chhota Shigri glacier, as reported by earlier workers ( Sharma 2007, Ramanathan et al. 2009, Singh 2011 ) . The spread secret plan of Na+K/TZ+ ( Fig. 3 ) shows that low mean tantamount ratio i.
e. 0.23 ( 0.17-0.
27 ) , bespeaking a comparatively little part of solute from silicate weathering.Chemical features of meltwater run outing from the glacier are chiefly controlled by enduring of newly weathered stone stuff at the base of the glacier and solid or liquid precipitation ( Ahmad and Hasnain 1999 ) . Higher temperatures are responsible for increasing biological activities, but besides the physical and chemical weathering of stone ( Rogora et al.
2003 ) . Surface H2O is peculiarly sensitive to alterations in temperature and precipitation government in mountain countries [ 20-22 ] . The partial or entire disappearing of lasting snowfields and the decrease of the ice screen period could take to a pronounced addition in the mineral disintegration owing to the greater proportion of precipitation fluxing over open stones and into the dirt [ 23, 24 ] . Decadal fluctuation in the major ion chemical science of meltwater run outing from Chhota Shigri glacier was studied by comparing the meltwater chemical science of August 2008 with antecedently published informations [ 11 ] in 1987 ( Fig. 4 and 5 ) . Table 2 summarizes the hydrochemistry of the meltwater in 1987 and 2008. Most cations like Ca2+ increased about 6 times, Mg2+ 87 times, Na+ 10 times and K+ 19 times, while anions like Cl- increased about 12 times, HCO3- 85 times and SO42- 49 times between 1987 and 2008, which could hold resulted from the warming that is reported in the Northwestern Himalaya [ 25 ] . Higher air temperatures would ensue in decrease of snow and ice screen and greater exposure of stones in glaciated water partings therefore heightening the weathering procedure, which could be the major factor responsible for increasing solute concentrations in the meltwater of Chhota Shigri glacier.
Mg2+ and HCO3- show a extremely important addition, which may be due to heighten carbonate weathering in a heating environment. Harmonizing to Rogora et Al. [ 26 ] fluctuations in base cations, alkalinity and sulfate can be explained in footings of an addition in solute export from the catchment due to intensified weathering in a heater clime. In cool climes enduring can besides accelerated by more exposure of minerals due to physical weathering of ice ( Turner et al. 2010 ) .
Very limited meteoric informations from Chhota Shigri glacier catchment is available during the studied period, and so it is hard to straight correlate the ascertained addition in ionic concentration in meltwater to climate alteration. However, mass balance, snout retreat, thinning and glacier shrinking are of import indexs of clime alteration. The available mass balance informations of Chhota Shigri glacier revealed a negative tendency ( Table 3 ) , and is discussed here in support of climatic impact playing a important function in heightening the ionic concentration in Chhota Shigri glacier meltwater. Shrinking or cutting of the glaciers is linked with clime alteration that consequences in lessening in winter precipitation ( solid ) and addition in summer precipitation ( liquid ) and atmospheric temperature [ 27 ] . Position of glacier neb is the simplest index of glacier retreat or progress over a period of the clip which by and large linked with climatic fluctuations ( Ramanathan 2011 ) . Snout retreat of Chhota Shigri glacier was estimated to be 53.3 myr-1 between 1988 and 2003 by field observation and remote feeling survey ( Kulkarni et al 2007 ) .
Whereas retreat of neb was estimated to be 25 myr-1 between 1972 and 2006 ( Shruti 2008 ) , but this survey has its ain restriction due to declaration of different images. Snout retreat of the glacier shows that glacier resigning portion of the country occupied by it means a greater exposure of stones, therefore heightening the weathering procedures. Which may be responsible for increasing the dissolved ions concentration of meltwater run outing from Chhota Shigri glacier.
Mass balance survey on Chhota Shigri glacier was carried out by Glacier Research Group, Jawaharlal Nehru University, New Delhi during the period 2002-2010, during which Chhota Shigri glacier showed negative mass balance. Annual specific mass balance of Chhota Shigri glacier was -1.4, -1.2, +0.1 and -1.4 m w.e.
in 2002-2003, 2003-2004, 2004-2005 & amp ; 2005-2006 severally [ 17 ] . Between 2002 and 2010, Chhota Shigri glacier experienced a negative glacier-wide mass balance of -0.67A±0.40m w.e.
a-1 [ 28 ] , bespeaking the possible glacier recession may be caused either by planetary clime alteration or local warming consequence in the part. Some recent distant feeling surveies indicate that overall deglaciation in Himachal Pradesh was every bit high as 21 % during the period 1962-2007 ( Kulkarni et al. [ 29 ] , 466 glaciers investigated ) , while during the period 1999-2004, a general cutting of glaciers in the Western Himalaya is observed ( Berthier et al. [ 30 ] , with an overall specific mass balance of -0.7 to -0.
85 thousand w.e.a-1 obtained over a 915 km2 ice covered country including Chhota Shigri glacier ) . Harmonizing to Wagnon et Al. [ 17 ] this fluctuation is due to increase in the gait of glacier wastage in the western Himalaya, likely related to planetary heating.Mass balance is strongly dependent on incoming solar radiation, which is irregularly absorbed by the glacier harmonizing to surface reflective power ( snow or ice, presence or absence of dust ) [ 17 ] .
Hence surface reflective power is likely to play an of import function in the thaw of glacier i.e. less albedo resulting in increased thaw and finally to negative mass balance. Negative glacier mass balance is besides the consequence of glacier resigning portion of the country occupied by it, therefore heightening the weathering procedures and the ionic concentrations in the meltwater watercourse. Warming besides gives rise to an addition in meltwater temperatures, which would speed up chemical weathering, let go ofing more ions into the portal meltwater.Change in ionic concentration of Chhota Shigri glacier meltwater during this period ( 1987-2008 ) can be partially explained as the impact of warming. Apart from clime alteration, chemical science of atmospheric deposition besides can play an of import function in finding chemical features of surface Waterss in distant countries, if we consider the geo-lithology of the water partings as a invariable, a farther variable strongly act uponing H2O chemical science [ 31, 32 ] . Thus the atmospheric radioactive dust over the Himalayan part could hold played a function in heightening the solute concentration observed in Chhota Shigri glacier meltwaters from the 1987 to 2008.
However, quantification of atmospheric radioactive dust to the hydrochemistry of Chhota Shigri glacier demands to be carried out to confirm the above illation in relation to the function of clime alteration.
The present survey was aimed at look intoing the factors responsible for heightening the major ion concentrations in Chhota Shigri glacier meltwater based on empirical grounds every bit good as time-series informations and secondary information. A comparing between the meltwater chemical science of 1987 and 2008 shows that most cations and anions increased 6 to 87-fold in concentration. This tendency can be related to higher air temperatures ensuing in decrease of snow and ice screen and attendant greater exposure of stones in this glaciated catchment, heightening the weathering procedure. At the same clip, the atmospheric radioactive dust over the Himalayan part in recent times could hold played a important function in supplying easy available beginning stuff for the enhanced solutes in glacier meltwaters.
The Writers are grateful to Department of Science and Technology ( DST ) , Govt. of India for funding the research undertaking on Chhota Shigri glacier. The writers are besides thankful to Jawaharlal Nehru University for supplying infrastructural installations for carry throughing this work.