Using natural 15N abundances to trace the fate of waste-derived nitrogen in forest ecosystems: New Zealand case studies.

Treatment of wastewater generally results in elevated natural 15N abundance (δ15N) in the effluent and sludges. For example, high δ15N values are found in treated sewage effluent, biosolids, and other wastes that are commonly applied to land. In contrast, N deficient coniferous forest soils usually have a low δ15N. When wastes with high δ15N values are applied to land, their distinctive δ15N signature can potentially be used to trace the fate of waste-derived N in the ecosystem. In this paper, we provide an overview of the use of δ15N in land application of wastes, including New Zealand case studies on tracing nitrogen in forest ecosystems.