Characterization of Major Inorganic Ions in Precipitation in Area of Hisar, India

Abstract

The rainwater samples were collected on event basis during June-July-August-2012 and were analyzed for pH, major anions (Cl, NO₃, SO₄) and cations (Ca, Mg, Na, K, NH₄). The pH value varied from 6.0 to 3 4 4 7.2 indicating alkaline nature of rainwater. The pH of the rainwater was found well above the reference pH (5.6), showing alkalinity during the monsoon season. The average and standard deviation of ionic composition was found to be 98.1±9.8 l eq L-1. The total anions contribute 48% and cations 52%, respectively to rainwater. Neutralization factors (NF) followed a sequence of NFCaNFMg (NFNH₄) with factors of 1.1, 0.36 4 and 0.16 indicating the crystal components are responsible for neutralization of anions. The average ratio of (NO₃+ Cl)/SO₄ observed as 1.2 indicates that nitric and hydrochloric acid influences the acidity of rainwater. 3 4 The ratio of NH₄/NO₃ and NH₄/SO₄ was observed as 0.7 and 0.3 thus indicates that the possible compounds which may predominate in the atmosphere are NH₄NO₃ and (NH₄)₂SO₄. Ionic correlation was established to 4 3 4 2 4 identify sources of origin. A good correlation was seen between Ca and Mg (r = 0.98); suggesting the common occurrence of these ions from crustal origin. Similarly, the acidic ions SO₄ and NO₃ correlated well (r = 70) indicating their origin from similar sources. Other relatively significant correlations were observed between Ca and SO₄ (r=0.93), Mg and SO₄ (r=0.76), Ca and NO₃ (r=0.07), Ca and Cl (r=0.28) and Mg and Cl (r=0.32), and Mg and NO₃ (r=0.69). The observed rainwater ratio of Cl/Na (1.4) is closer to that of seawater ratio (1.18) 3 indicates fractionation of sea-salt and modifications by non-marine constituents as the site is 2040 km away from the sea coast. The nss-Ca contribution was observed as 95.7% suggesting their crustal origin whereas nss-Mg and nss-K shows their contribution as 86.8% and 83.9% indicating influence of soil sources. The nss-SO₄ contributed as 86.7% shows anthropogenic origin.