III. SHENYANG CITY: CURRENT ENVIRONMENTAL SITUATION
B. Assessment and changing trends of environmental quality in Shenyang City
1. Air quality
The air quality in Shenyang City lies within the middle level of pollution. The pollution problem is serious during winter, slight in the summer, and moderate during the other seasons. It is serious in the industrial and communicational areas and slight in the residential areas, and is heavier in the morning and lighter in the evening. Data on atmospheric environmental quality in 1995, in accordance with national standards, showed that TSP and S02 were at the third class level, while CO and NOx were at the second class level.
The atmospheric environmental quality in Shenyang is evaluated by the synthetic index method. The evaluation standard is the second class standard for the daily average (GB3095-82). Table 2 shows the index classification. Table 3 shows the annual averages of the air index calculated from 1991 to 1995.
Table 2. Classification of the synthetic index
Table 3. Average of atmospheric synthetic index in Shenyang, 1991 to 1995
Based on data for 1985 to 1995, the changing trends in the levels of the key pollutants (TSP, SO2 and NOx, dust and CO) are given in figures 8-10. Figures 11 and 12 show the changes in COD and BOD levels and the annual average levels of oil and volatile phenolphthalein in the Shenyang section of the Hunhe River.
<>Note: the values on the graph for TSP = the measuring values in 1986.
Figure 8 Changes in TSP levels
Note: the values on the graph, of SO2 and NOX = the measuring values in 1986
Figure 9. Changes in SO2 and NOx levels
Note: the values on the graph for dust and CO = the measuring values in 1986.
Figure 10. Changes in dust and CO levels