Leaching of metals from asphalt pavement incorporating municipal solid waste incineration fly ash.

Rising municipal solid waste incineration (MSWI) makes it imperative to recycle the fly ash (FA). FA can be solidified by asphalt and then applied in the asphalt road. However, little information on the metal leaching and associated with risks from asphalt solidified forms for FA is available. In the present study, metal leaching characteristics and long-term leaching potential from the asphalt-based FA matrices was determined based on the national standard method and simulating the actual using of the solidified forms in highways, respectively. The immobilization effect of asphalt on MSWI FA is well. Leaching velocity was in the order of magnitude of 10~10-6 cm h-1 during the entire leaching period. At the early age, leaching velocity of metals is high, especially Zn, Cd, and Ba. Cumulative leaching concentration of metals and leaching time has positive correlation. Only considering the leaching of simulating acid, leaching of metals in asphalt-based matrices is very slow, and the leaching toxicity of metals is lower than the Chinese National Standard.

Characteristics of groundwater recharge on the North China Plain.

Groundwater recharge is an important component of the groundwater system. On the North China Plain (NCP), groundwater is the main water supply. Because of large-scale overexploitation, the water table has declined, which has produced severe adverse effects on the environment and ecosystem. In this article, tracer experiment and watershed model were used to calculate and analyze NCP groundwater recharge. In the tracer experiment, average recharge was 108 mm/year and recharge coefficient 0.16. With its improved irrigation, vegetation coverage and evapotranspiration modules, the INFIL3.0 model was used for calculation of groundwater recharge. Regional modeling results showed an average recharge of 102 mm/year and recharge coefficient 0.14, for 2001-2009. These values are very similar to those from the field tracer experiment. Influences in the two methods were analyzed. The results can provide an important reference for NCP groundwater recharge.

[Ear shape of corn and its relations to grain yield under stress].

To quantify the ear shape of corn (Zea mays L.) and to understand the effects of growth stress on the ear shape are of importance in corn crop science. By means of digital image analysis on whole ear RGB images, and using the definition of extent (E), volumetric odds (V), longitudinal centroid (L), transverse centroid (T), and sphericity (S) to represent the similarity to rectangle, volumetric equality, longitudinal symmetry, transverse symmetry, and similarity to sphere, respectively, the ear shape data from the field experiment with 2 corn cultivars, 2 contrast growth conditions, and 2 defoliation treatments in a split plot design were analyzed by cluster analysis, canonical variate analysis, and variance analysis. It was found that within the first 2 weeks after silking, the ear shape varied obviously, namely, the E increased from 0.72 to 0.78, the S from 0. 40 to 0. 48, while the L decreased from 0.56 to 0.51, the T decreased from 0.02 to 0.01, and the V decreased from 0.25 to 0.21. Afterwards, all the 5 shape traits tended to be stable. Growth stress (high planting density and zero fertilizer application) shifted the E by -4.5% and the V by +17.7% at maturing stage, which, combined with the variation of ear length and width, contributed 87% - 97% of grain yield change. Throughout the ear growth duration, the ear shape traits L, V, and S were more sensitive to growth stress, being considered as the potential quantitative indicators of stress.