Identification of groundwater contamination zone around a reclaimed landfill using carbon isotopes

Abstract

Chemical and isotopic analyses of groundwater from piezometers localized around a reclaimed landfill were performed in order to identify the boundaries of groundwater contamination zone. Spatial distribution of dissolved inorganic carbon (DIC) concentration and stable carbon isotopes in the groundwater was used to distinguish the piezometers localized within the contaminated aquifer. Background groundwater was characterized by low DIC concentration (from 1.8 to 5.0 mmol/L) and negative values of δC (from -20.6‰ to -12.4‰). Higher DIC concentrations (from 6.0 to 12.5 mmol/L) and higher values of δC (from -10.9 to +3.6‰) were determined in groundwater contaminated by landfill leachate. The study confirmed that δC value in the groundwater was a useful tracer in determining the extent of the contamination zone around the landfill. In general, upgradient from the landfill, carbon isotopic composition of groundwater depended on natural sources of carbon and δC values were negative. Downgradient from the landfill, where groundwater was contaminated by the landfill leachate, δC values were higher, sometimes even positive.

Application of 2H and 18O Isotopes for Tracing Municipal Solid Waste Landfill Contamination of Groundwater: Two Italian Case Histories

“…Several studies [14,[29][30][31] have highlighted how methanogenesis processes can affect leachate enrichment in δ 2 H. As a matter of fact, the methanogenic bacteria, during the methane production, use first the "lighter" isotope of hydrogen ( 1 H), therefore leaving enriched the "heavier" isotope of hydrogen in leachate ( 2 H) [8,22,23,32].…”

Precipitation Method for Determination of Carbon and Oxygen Isotopes to Detect Groundwater Contamination Near a Municipal Landfill

“…2 [8,9,11]. The leachate-contaminated groundwater is isotopically distinct from the natural groundwater.…”

“…2 Relationship between δ 13 C DIC and 1/DIC [8,9,11] leachate-contaminated groundwater and heavy carbon isotope ratios δ 13 C DIC can be used to diagnose the landfill contamination. Leachate-contaminated groundwater was characterized by high values of δ 13 C DIC (from −10.9 to +3.6‰) and high DIC concentration (from 6.0 to 12.5 mmol/L) [8,9,11]. Lower values of δ 13 C DIC (from −20.6 to −12.4‰) and lower DIC concentration (from 1.8 to 5.0 mmol/L) were determined in the natural groundwater.…”

“…Usefulness of carbon isotope studies to assess the impact of municipal landfills on groundwater is discussed by many authors [5][6][7][8][9][10][11][12][13][14]. Sometimes the researchers measure water content of δ 2 H, δ 18 O, and δ 13 C DIC to identify the leachate-contaminated groundwater near the landfills [13].…”

“…This knowledge is crucial for a consistent interpretation the results of environmental analyses especially from polluted sites, and pollution source characterization and tracking, where there is often substantial heterogeneity of the environmental samples. Usefulness of isotope studies to assess the impact of municipal landfills on groundwater is widely discussed by many authors [4][5][6][7][8][9][10][11][12][13][14]. The stable isotopic methods are highly trusted and commonly uses to distinguish reaction mechanisms within the degrading compounds.…”