[Evaluation indices of greenhouse gas mitigation technologies in cropland ecosystem].

In spite of the increasing studies on greenhouse gas (GHG) emissions mitigation technologies, there is still a lack of systematic indices for evaluation of their overall impacts in croplands. In this study, we collected all the indices relating to greenhouse gas emissions and analyzed each index following the principles of representativeness, objectivity, completeness, dominance and operability. Finally, we proposed evaluation indices for mitigation technologies based on the current situation of China. Crop yield per unit area was proposed as a constrained index, and greenhouse gas emissions intensity, defined as GHG emissions per unit of produced yield, was proposed as comprehensive index to evaluate the greenhouse effect of various croplands mitigation technologies. Calculation of GHG emissions intensity involved yield, change of soil organic carbon, direct N2O emissions, paddy CH4 emissions and direct and indirect emissions from inputs into croplands. By following these evaluation indices, the greenhouse effect of the technologies could be well evaluated, which could provide scientific basis for their further adoption.

[Application of DNDC model in estimating cropland nitrate leaching].

The leaching amount of soil water and nitrate from winter wheat field under typical planting system in Jinan City of Shandong Province was measured with lysimeter during the whole growth season in 2008, and the feasibility of applying DNDC model to estimate this leaching amount was tested by the obtained data. On the whole, DNDC model could better simulate the soil water movement in the crop field, with the accuracy being acceptable. However, there existed definite deviation in the simulation of nitrate leaching. The simulated value (18.35 kg N x hm(-2)) was 3.46 kg N x hm(-2) higher than the observed value (14.89 kg N x hm(-2)), with a relative error of about 20%, which suggested that some related parameters were required to be further modified. The sensitivity test of DNDC model showed that cropland nitrate leaching was easily to be affected by irrigation and fertilization. It was proved that the model had definite applicability in the study area.

In vivo study effect of particulate Bioglass in the prevention of infection in open fracture fixation.

There are many in vitro experiments showing that particulate bioactive glasses have a broad and certain antibacterial effect, but there is no report about this antibacterial effect in vivo so far. The aim of this study is to examine the efficacy of particulate Bioglass in reducing the rate of infection with Staphylococcus aureus after the fixation of open tibial fractures in rabbits. The test in vivo was carried out with male rabbits split into two groups infected with Staphylococcus aureus at the right tibial fracture sites fixed with plate and screw, either with or without bioactive glass respectively. Culture results show that six of ten rabbits from the control group had a positive culture for the strain of Staphylococcus aureus ATCC25923, compared with six of the nine rabbits from the Bioglass group. The median radiographic score is 4.5 points for the rabbits from the control group and 4 points for the rabbits from the Bioglass group. The median histopathological score was 2.5 points for the rabbits in the control group and 3 points for the rabbits in the Bioglass group. In conclusion, this study showed no significant difference between the rates of infection of two groups. Particulate Bioglass did not reduce the rate of infection with Staphylococcus aureus after the fixation of open tibial fractures in rabbits.

[Estimation of CO2 and N2O emissions from farmland soils in Hebei Province in Huang-Huai-Hai Plain].

Taking Hebei Province in Huang-Huai-Hai Plain as a study case, the DNDC model was tested with field observation data, and used to estimate the farmlands CO2 and N2O emissions. The results showed that the simulated results could better reflect the characters of soil CO2 and N2O emissions, and the total CO2 and N2O emissions from the farmland soils in 111 counties of Hebei Province in 2003 were estimated to be 3.758 x 10(6) t C and 40.345 x 10(6) kg N, respectively. Winter wheat/ summer maize rotation fields contributed about 40% of the CO2 and N2O emissions, and thus, the mitigation of farmland soil CO2 and N2O emissions should be focused on the high CO2 and N2O emission counties, especially on the winter wheat/summer maize rotation fields in these regions. It could be unnecessary or non-effective to mitigate the CO2 and N2O emissions at large scale.