Nitrate sources and formation of rainwater constrained by dual isotopes in Southeast Asia: Example from Singapore.

Emission of reactive nitrogen species has a major impact on atmospheric chemistry, ecosystem and human health. The origin and formation mechanisms of wet-deposited nitrate are not well understood in Southeast Asia (SEA). In this study, we measured stable isotopes of nitrate (δN and δO) and chemical compositions of daily rainwater from May 2015 to July 2017 in Singapore.