Assessment of nitrate-N contamination in the Chunnakam aquifer system, Jaffna Peninsula, Sri Lanka

Abstract

Jaffna peninsula in Sri Lanka is an area of intensive agriculture using extensive organic and inorganic nitrogenous compounds and hence, this study was focused on assessing vulnerability of karstic aquifer system with specific focus on nitrate contamination, and compare loads of nitrate from agriculture. The total number of the wells sampled in the Chunnakam aquifer is 44. The coverage of wells with measurements of nitrate and nitrite concentrations in the database covering the study period from Januray, 2011 to August, 2011. The intrinsic vulnerability of the area is estimated by the DRASTIC model and the modified DRASTIC method was used to determine the nitrate-specific vulnerability of the aquifers. Average concentrations of nitrate-N and nitrite-N during the study period were 4.869 and 0.014 mg/L respectively. The average number of wells exceeding permissible level of NO3–N is approximately 6–12, which means that about 14-28% out of the 44 wells. Modified DRASTIC (DI) index value computed as explained above increased from DI = 177 to a range of 182 to 197. In spite of the increase, the Modified DI values show that the aquifer vulnerability specific to nitrate contamination remains in “high” category. Although nitrogen loading at the domestic sources and irrigation is of the same order of magnitude, the loading from fertilizer input is much larger which is about 15 times higher. This finding suggests that the fertilizer input in agricultural areas constitute a significant contribution to the nitrogen content in the groundwater and soils in agricultural areas of Jaffna.

Using intrinsic vulnerability and anthropogenic impacts to evaluate and compare groundwater risk potential at northwestern and western coastal aquifers of Sri Lanka through coupling DRASTIC and GIS approach

“…Most previous research in various regions of Sri Lanka has been carried out to characterize the impact of groundwater quality from anthropogenic sources, but not much tried with the detailed assessment of groundwater vulnerability to predict and delineate the groundwater protection area of the area by determining their natural vulnerability against the contaminant from acts of human using GIS-based DRASTIC method/model. Up to now, several applications of DRASTIC method have been studied at some areas of Sri Lanka such as Kalpitiya peninsula and part of Puttalam area at the northwestern coast (Jayasekera et al 2008 and, Kalpitiya and Mannar area at the north-western coast (Jayasingha et al 2015), Jaffna peninsula at the northern coast (Vithanage et al 2014), and Walawe River Basin at the southern region (Ranjan 2005;Sarukkalige et al 2007). Even though there are several studies on application of DRASTIC method, it could provide some conceptual clues and light to compose a comprehensive research at the north-western and western coastal aquifers, particularly Kalpitiya Peninsula, Vanathavillu Basin, and Katana area.…”

Geochemical Characterization and Water Quality Index Based Assessment of Groundwater Quality Using GIS In Tropical River Basin: Case Study in Kirama-Ara River Basin, Southern Province, Sri Lanka.

“…NO3contamination affects 6.25% (G16) of samples, according to WHO (2017). Nitrogenous fertilizer usage in agricultural areas has a deleterious influence on NO3accumulation in groundwater (Vithanage et al, 2014). Additionally, improper domestic sewage disposal, animal and organic waste, and septic tank leaking can all raise groundwater nitrate levels (Udeshani et al, 2022).…”

“…DWQI also has a significant positive connection with NO 3-, PO4 3-, SO4 2-, Ca 2+ , K + , and Na + . Nitrate is a water quality component that has been identified as having a major detrimental influence on human health (Dissanayake & Chandrajith, 2018;Indika et al, 2022;Vithanage et al, 2014). in the water sample can also alter how limestone and sandstone weather (Adimalla & Taloor, 2020;Qureshi et al, 2021).…”

Farmer Perception, Environmental Awareness, and Overuse of Fertilizer in Kalpitiya: A Preliminary Investigation using Bayesian Econometrics

“…In the present scenario, most agricultural lands have been used for more than 100 or several years for agricultural purposes. Because of this continuous usage of lands and the application of chemical fertilizer, soil quality is being declined In the Sri Lankan context, farmers often resort to easily available chemical fertilizers and in most intensively cultivated vegetable fields; farmers rely on applying high quantities of chemical fertilizers (Vithanage, et al, 2014).…”