Fig. 4. Relationships between N deposition and gross domestic product per capita on a global scale.

Relationships between total N (a, d), NHx (b, e) and NOy (c, f) deposition and gross domestic product per capita (GDPpc). The data used in a–c are observations of N deposition and GDPpc; those in d–f are the logarithmic values of N deposition and of GDPpc. African countries are Niger, Mali, Cameroon and Cote d’Ivoire. Southeast Asian countries are Vietnam, Malaysia, Indonesia and Thailand. East Asian countries are China, South Korea and Japan. Western European countries are EU countries (EU27). North American countries are the United States and Canada. R² is the coefficient of determination, ** represents the significance level at P = 0.01. Source data are provided as a Source Data file.