Variability of Anaerobic Animal Waste Lagoon delta¹⁵N Source Signatures

Abstract

High ammonium-N concentrations derived from animal wastes stored and partially treated in earthen anaerobic lagoons at confined feeding facilities can seep to groundwater. δ 15 N-NH 4 + values from +2.0 to +59.1‰ in 13 lagoons complicate identification of lagoon seepage as well as land-applied lagoon effluent in ground and surface waters. The spectrum of δ 15 N values requires site-specific isotope characterization of the potential source. Feed and fresh manure and urine δ 15 N values indicate that most N isotopic fractionation occurs after excretion. Lagoon management clearly affects enrichment. δ 15 N-total Kjeldahl N (TKN) and δ 15 N-NH 4 + within each lagoon were not statistically different. δ 15 N-NH 4 + within the top 1.5 m of the lagoons was spatially uniform (CV [coefficient of variation] <5%).

Integrated Deep Soil N and Groundwater Isotope Investigation of N Sources Captured by Municipal Wells

“…While the δ 15 N values of fresh cattle urine and manure (+1.7 and + 4.8‰, respectively) (Gormly and Spalding ) are quite light, they become rapidly enriched via ammonia volatilization after excretion and deposition on soils or storage in waste lagoons. Gormly and Spalding () reported δ 15 N values for total reduced N in compacted manure of feedlots exceeded +13‰ while δ 15 N NH4 values in 13 CAFO lagoons collected during five sampling events averaged +13.7 to +21.8‰ (Mariappan et al ).…”

Spatial and temporal patterns of nitrogen isotopic composition of ammonia at U.S. ammonia monitoring network sites

“…Throughout the warming season, the 'pool' of δ 15 N-NH 4 + in livestock waste storage units (e.g. lagoons) can increase up to 20‰ (Karr et al, 2003;Mariappan et al, 2009) due to continued favorable volatilization of lighter 14 NH 3 . If the δ 15 N of the NH 3 emission source is increasing up to 20‰ and the NH 4 + (aq) to NH 3(g) fractionation stays relatively consistent, the overall δ 15 N-NH 3 of emitted NH 3 can increase up to 20‰ over the course of a summer season.…”

An extraction method for nitrogen isotope measurement of ammonium in a low-concentration environment

“…One study of the δ 15 N(NH + 4 ) composition of atmospheric particles in Lyon (150 km from Mont Blanc) has shown that the pollution peaks of ammonium nitrate in spring were accompanied by a strong decrease in δ 15 N (Favez et al, 2021), potentially explained by agricultural sources (livestock or fertilizers). However, this and other studies highlight the lack of broad understanding of isotopic variations over the rest of the year and difficulties in assigning diagnostic isotopic labelling to different emission pools (Mariappan et al, 2009;Felix et al, 2017;Favez et al, 2021).…”