Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.

In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase

Inhibiting Aspergillus flavus growth and degrading aflatoxin B1 by combined beneficial microbes

Aflatoxin B1 (AFB1) is a type of toxin produced by Aspergillus flavus, which has a negative effect on animal production and economic profits. In order to inhibit A. flavus growth and degrade aflatoxin, the optimal  proportion of beneficial microbes such as Lactobacillus casei, Bacillus subtilis and Pichia anomala were selected. The results show that AFB1 production and mycelium weight of A. flavus was decreased by more than 34 folds (161.05 vs. 4.69 µ/L) and 7.7 folds (6.98 vs. 0.90 mg/ml) with the free-cell supernatants of L. casei and B. subtilis (P<0.05), respectively. The optimal proportion of L. casei, B. subtilis and P. anomala was 2:1:2 for inhibiting A. flavus growth determined by 3x3 orthogonal design. Based on the optimal proportion of three microbial species, the maximum AFB1 degradation was during 24 to 48 h incubation (P<0.05). When three species of beneficial microbes were mixed with yeast cell wall and oligosaccharide, both of them could not help the microbes in AFB1 degradation. The combined microbial incubation showed that AFB1 contents in the supernatant and cells were 10.25 (P<0.05) and 3.34 µg/L, lower than the control group (68.55 µg/L), indicating that most of the AFB1 were degraded by the microbes and only a little of them were absorbed and deposited in microbial cells.Key words: Aspergillus flavus, aflatoxin B1 detoxification, beneficial microbes, yeast cell wall, oligosaccharide