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Abstract: Monthly nitrogen isotopes of ammonium and nitrate in wet deposition in the city of Guangzhou, and the causes of their variability, are reported in this paper. Nitrate δ15N showed nearly constant values around zero in the dry season (October to April), but oscillating values from negative to positive in the rainy season (May to September). By contrast, ammonium δ15N displayed lower values during the rainy season than in the dry season. The rural area north of the city was considered as the prominent source of ammonium and nitrate in spring and early summer (May and June), as suggested by their concurrent negative isotopic trends and higher NH4 +/NO3 − ratios. From July to September, different dominating sources from the city, i.e., fossil fuel combustion for nitrate, and sewage and waste emission for ammonium, caused disparate δ15N trends of the two species, showing positive nitrate δ15N, but still negative ammonium δ15N. During the cool dry season, the high values of ammonium δ15N and concurrently low NH4 +/NO3 − ratios suggested the decrease in NH3 volatilization and relatively important thermogenic origin of ammonium, but the intermediate nitrate δ15N values around zero may be a result of a balanced emission of NOx from the city and the rural areas. The isotopic effects of chemical conversion of NOx to nitrate and washout of nitrate were ruled out as significant causes of nitrate δ15N variability, but ammonium washout, during which 15N is assumed to be preferentially removed, may partly contribute to the ammonium δ15N variability. [Copyright &y& Elsevier]

The escalation of risks associated with environmental and climatic aspects has accelerated the introduction of voluntary personal carbon trading (PCT), a policy instrument for promotion and facilitation of low-carbon behavior in the domestic sector. This paper examines participants' motivation in the Guangdong pilot project, which aims to develop the first voluntary PCT scheme (Carbon Generalized System of Preferences, CGSP) in China to reduce the domestic sector's emissions and increase the liquidity of the Guangdong pilot emission trading scheme. The CGSP acceptance model is based on the technology acceptance model and explores the drivers of the public's participation willingness (PW) in the CGSP scheme. Further, the structural equation model has been adopted to explore the influence paths of each driver by using survey data (N = 1190) collected from Guangzhou, Guangdong Province, China. The empirical results demonstrated that the strong and direct drivers are associated with the institutional technical environment, perceived usefulness and participation risk. However, other drivers affect PW through the mediation effect of perceived usefulness. Notably, implementation cost had no significant effect on PW. • An innovative voluntary personal carbon trading scheme in China was introduced. • A conceptual model was proposed to study the determinants of public acceptance. • Structural equation model was used to study the influence path of each determinant. • Both the direct and indirect paths of each determinant have been analyzed in depth. [ABSTRACT FROM AUTHOR]