Methylmercury biomagnification in aquatic food webs of Poyang Lake, China: Insights from amino acid signatures.

As the dominant mercury species in fish, methylmercury (MeHg) biomagnifies during its trophic transfer through aquatic food webs. MeHg is known to bind to cysteine, forming the complex of MeHg-cysteine. However, relationship between MeHg and cysteine in large-scale food webs has not been explored and contrasted with MeHg biomagnification models.

How aerosol pH responds to nitrate to sulfate ratio of fine-mode particulate.

Aerosol acidity (pH), one of key properties of fine-mode particulate (PM), depends largely on nitrate and sulfate in particle. The mass contribution of nitrate relative to sulfate in PM has tended to increase in many regions globally, but how this change affects aerosol pH remains in debate. In this way, we measured PM ionic species and oxygen isotopic composition of nitrate in the eastern China, and predicted aerosol pH using the ISORROPIA-II model.

Rayleigh based concept to track NOx emission sources in urban areas of China.

Despite the implementation of some effective measures to control emissions of nitrogen oxides (NOx = NO + NO) in recent years, the ambient NOx concentration in urban cities of China remains high. Therefore, a quantitative understanding of NOx emission sources is critical to developing effective mediation policies. In the present study, the dual isotopic compositions of nitrate (p-NO) in fine-particle aerosol (PM) collected daily at a regional scale (Beijing-Tianjin-Shijiazhuang) were measured to better constrain the NOx emission sources.

Reducing N losses through surface runoff from rice-wheat rotation by improving fertilizer management.

To better understand N runoff losses from rice-wheat rotation and demonstrate the effectiveness of improved fertilizer management in reducing N runoff losses, a field study was conducted for three consecutive rice-wheat rotations. Nitrogen losses through surface runoff were measured for five treatments, including CK without N application, C200, C300 simulating the conventional practices, CO200, and CO300. Optimum N rate was applied for C200 and CO200, and 30% of chemical fertilizer was substituted with organic fertilizer for CO200 and CO300 with respect to C200 and C300, respectively.