Papers by Author: Jin Feng Song

Abstract: The seasonal variation and influence factors of emission of greenhouse gasses (CH₄ and N₂O) from the different water depths were studied during the growing seasons in a marsh wetland of Sanjiang Plain of China. The results showed that the wetland was a source of both CH₄ and N₂O during the growing seasons and emissions showed conspicuous temporal and spatial variations. Emission rates of CH₄ were higher in July and August while N₂O were higher in June and July. The highest average CH₄ flux among the four sites was in the water depth at 40cm with a rate of 37.00 mg•m^-2•h^-1 and the lowest was in the water depth at 0cm with a rate of 8.13 mg•m^-2•h^-1. While the highest average N₂O flux was in the water depth at 0cm with a rate of 0.063 mg•m^-2•h^-1 and the lowest was in the water depth at 60cm with a rate of 0.034 mg•m^-2•h^-1. Further analysis indicated that water depth at 40cm and the soil temperature at 5cm were the main factors affecting CH₄ emission. Water depths at 0 and 40cm were the main factors affecting N₂O emission. Air temperature and surface soil temperature were not the main factors affecting CH₄ and N₂O emissions.

Abstract: The effects and mechanism of different concentration organic acids and organic salts solution on Al availability of dark brown forest soil were studied. It was resulted that, oxalic acid/oxalate and citric acid/citrate substantially stimulated soil Al release of dark brown forest soil. The effect of organic acids/salts on Al release would be strengthen with increasing of their concentrations.The contents of Al released from A1 horizon was higher than that from B horizon. Organic salt solutions had much higher effects than organic acid the same in concentration, i.e. citrate>citric acid, oxalate>oxalic acid. Therefore, the mechanism of organic acid/salts triggering release of soil Al was assumed to be dominated by complexation reactions of organic anions. Citric acid/ citrate had much higher effect than oxalic acid/ oxalate at same concentration to A1 and B horizons, i.e. citrate> oxalate, citric acid>oxalic acid, which was primarily related with the greater complexing capacities and dissociation constants of citric acid.

Abstract: By simulating oxalic and citric acid concentrations in forest litter leachates,a series of experiments were conducted to study the effects of oxalic acid and citric acid solutions on chlorophyll contents and photosynthesis of Fraxinus mandshurica seedlings.It resulted that, organic acids of appropriate concentrations increased chlorophyll contents, chlorophyll a and chlorophyll b contents varied more than carotenoid content, and 1.0mmol/L solution was best. To photosynthesis, the variability treads of net photosynthetic rates with organic acids were probably consistent to those with distilled water, but the values all increased, and 5.0mmol/L solution was best. Effects of different organic acids on chlorophyll contents and photosynthesis followed the series: citric acid >oxalic acid, and it might be relative to chemical structure, dissociation constants and organic ligand-metal stabilities of two kinds of organic acids.