Through the river model test,the relation between the critical sediment concentration and the ratio of width to depth of river channel under different widths,depths,discharges and sediment concentrations conditions is analyzed.

This paper summarizes recent research results on soil element background values and heavy metal environmental capacity in the region, and discusses the differentiation pattern of the environmental background value and critical content of the main zonal soils in Guangdong.

By pot culture experiment, the effects of lead added to latosol with different concentrations on peanut crop growth and remains were studied, and the referential critical content of lead in peanut crop was fut forward from the aspects of hygienic quality of agricultural product and effect of crop.

Firstly,this paper experimentally made a study of the explosion limit rules of flammable gas(CH4)and its change rule of critical content of oxygen after inert gas(N2)was added into it,and measured the explosion limit range of methane and its safety content of oxygen.

Dynamics of absorption and accumulation of Lentinula edodes accumulated heavy metals from culture medium and critical contents;

The characteristic drying curve of PVC was achieved and it can be expressed by The critical moisture content xc and the mass transfer coefficient K was measured, and its value was about 2% and 6×10-4 kg·-2 m-2· s-1 respectively.

The replacement medium and concentration, critical oxygen content, critical methane content are determined by analyzing the components of inflammable gases and their explosive limits.