PAHs pass through the cell wall and partition into organelles of arbuscular mycorrhizal roots of ryegrass.

The subcellular process and distribution of polycyclic aromatic hydrocarbons (PAHs) in arbuscular mycorrhizal plants remains to be elucidated. This work used a greenhouse experiment to show that, accompanied by the apoplastic and symplastic water movement through the root, acenaphthene (ACE) as a representative PAH passed through the cell-wall boundary, dissolved in the cell solution, and partition organelles in arbuscular mycorrhizal roots of ryegrass (Lolium multiflorum Lam.). The observed concentrations of ACE in organelles were 0.6 to 4.4 times higher than in the cell walls. The cell wall and organelles were the dominant storage domains for ACE in the root, and the distribution of ACE in cells of mycorrhizal ryegrass roots was, in descending order, cell organelles (40.8-70.8%) > cell wall (19.7-3.8%) cell solution (9.6-20.5%).

Characteristics and kinetics of ammonia and N2O emissions of aged refuse irrigated from landfill leachate.

This is the first attempt to report the gaseous nitrogen emissions from landfill leachate filtration methods by irrigating the aged refuse. A first-order reaction model was a good fit for the increase in ammonia emissions from aged refuse, clay and sandy soil incubated for 120 h after adding the leachate-N solution. The emissions of ammonia and N2O by the three experimental materials fit well to first-order and zero-order models, respectively. The maximum ammonia emission from aged refuse was approximately 1.17 mg NH4(+)-Nkg(-1) d.w. and the calculated emission factor was 1.95‰, which was 3.76 and 2.67 times lower than that of sandy and clay soils, respectively. The tendencies of NH4(+)-N nitrification and NO3(-)-N generations fit well to the zero-order reaction model and the net nitrification rate by the aged refuse was 1.30 (p<0.05) and 1.71 (p<0.05) times that of clay soil and sandy soil, respectively. At the same time, the net NO4(-)-N generation rate by the aged refuse was 1.56 (p<0.05) and 2.33 (p<0.05) times that of clay soil and sandy soil, respectively. The quantity of nitrogen emitted by aged refuse as N2O was 2.46 times greater than that emitted as ammonia. The emission factor for N2O from aged refuse was 8.28 (p<0.05) and 16.11 (p<0.05) times greater than that of clay and sandy soils, respectively. For the leachate irrigation, N2O emissions should be of greater concern than ammonia emissions.