Nitrate contamination of groundwater in the Republic of Lithuania

Abstract

In many countries nitrate contamination of groundwater has become a serious ecological problem and Lithuania is no exception.In fact,irrational, unbalanced development of the economy coupled with specific geological and climatic condi- tions have led to nitrate contamination on such a scale that it has become the object of interest for specialists of neighbouring countries. Contamination is worst in the vicinity of fertilizer factories and intensity manured agricultural land. Excessive nitrogen concentrations, typically as nitrates, are common in unconfined groundwater which is vulnerable to direct contamination from the land surface and the atmosphere. In deeper aquifers, apparently relatively isolated from surface pollution, ammonium is prevalent. Nitrogen contamination of groundwater shows a clear increasing tendency with time. Nitrogen compounds are not necessarily stable. They can be affected by various biochemical reactions. In these reactions, interconversion between nitrates, nitrites and ammonium can occur, as well as denitrification (i.e. loss to the atmosphere as nitrogen gas). Thus, groundwater can purify itself from such contamination with time.