III. SHENYANG CITY: CURRENT ENVIRONMENTAL SITUATION
B. Assessment and changing trends of environmental quality in Shenyang City
3. Underground water
According to data collected during many years of monitoring wells for irrigation and factory use, underground water is polluted mainly by organic pollutants, similarly to surface water pollution. The key pollutants are volatile phenolphthalein, NO-3-N, NO-2-N and NH3-N.
On the basis of the assessment method stipulated in the national GB/T14848-93 (standard of underground water quality), 15 indexes were selected and a synthetic assessment was made using monitoring data for 1995. A map of the comprehensive assessment of underground water quality in Shenyang is given in figure 15. Changes in underground water pollution levels are illustrated in figures 14, 16 and 17.
Note: the values on the graph, of volatile phenolphthalein = the measuring values in 1986.
Figure 14. Average annual changes in volatile phenolphthalein levels in underground water.
Figure 15. Synthetic assessment of underground water in Shenyang, 1995
Note: the values on the graph, of NO3-N = the measuring values in 1986.
Figure 16. Average annual changes in NO3-N levels in underground water
Note: the values on the graph, of NH3-N = the measuring values in .
Figure 17. Average annual changes in NH-3-N levels in underground water