(5) Health risk assessment of groundwater environment
Based on the hydrogeological conditions of the landfill and the basic conditions
around the site, the groundwater recharged by precipitation infiltrates into the
magmatic rock aquifer or it is discharged into Shenxian Ditch through short-range
runoff. A total of 107 households in Fengshui Village are distributed 403–1083 m
from the landfill, of which 8 households use wells to draw water, and the rest 99
households rely on surface water, so the pollution plume of the landfill covers
drinking water sources. Using the pollutant identification method provided by the
Guidelines for Health Risk Assessment for Contaminated Groundwater (Trial),
combined with the water quality monitoring results in Table 5.64, pollutants covered by the drinking water standards do not exceed the limits, but chloride,
ammonia nitrogen and fluoride which are not covered by such standards are
detected. Hence, the health risk assessment of groundwater environment considers
chloride, ammonia nitrogen and fluoride only. The screening levels for chloride,
ammonia nitrogen, and fluoride are calculated using the HERA model.
Table 5.64 Water quality monitoring results for samples Q1–Q3 (Unit: mg/L)
Item
Observed
values
Evaluation
values
Grade III standards
Q1
Q2
Q1
Q2
pH
8.1
7.8
0.733
0.533
6.5–8.5
Total hardness
275
245
0.611
0.544
450
Total soluble solids
308
302
0.308
0.302
1000
Sulfate
20.8
42.5
0.083
0.170
250
Chloride
0.40
0.46
0.002
0.002
250
Iron
0.026
ND
0.087
ND
0.3
Manganese
ND
ND
ND
ND
0.1
Copper
ND
ND
ND
ND
1.0
Zinc
ND
ND
ND
ND
1.0
Volatile phenols
ND
ND
ND
ND
0.002
Permanganate index
1.3
1.6
0.433
0.533
3.0
Nitrate
0.35
0.18
0.018
0.009
20
Nitrite
ND
ND
ND
ND
0.02
Ammonia nitrogen
ND
ND
ND
ND
0.2
Fluoride
0.23
0.09
0.230
0.090
1.0
Cyanide
ND
ND
ND
ND
0.05
Mercury
ND
ND
ND
ND
0.001
Arsenic
ND
ND
ND
ND
0.05
Cadmium
ND
ND
ND
ND
0.01
Chromium (hexavalent)
ND
ND
ND
ND
0.05
Lead
ND
ND
ND
ND
0.05
Selenium
ND
ND
ND
ND
0.01
Anionic synthetic detergents
ND
ND
ND
ND
0.3
5.3 Southwest China
215
Based on the hydrogeological conditions of the landfill and the basic conditions
around the site, the groundwater recharged by precipitation infiltrates into the
magmatic rock aquifer or it is discharged into Shenxian Ditch through short-range
runoff. A total of 107 households in Fengshui Village are distributed 403–1083 m
from the landfill, of which 8 households use wells to draw water, and the rest 99
households rely on surface water, so the pollution plume of the landfill covers
drinking water sources. Using the pollutant identification method provided by the
Guidelines for Health Risk Assessment for Contaminated Groundwater (Trial),
combined with the water quality monitoring results in Table 5.64, pollutants covered by the drinking water standards do not exceed the limits, but chloride,
ammonia nitrogen and fluoride which are not covered by such standards are
detected. Hence, the health risk assessment of groundwater environment considers
chloride, ammonia nitrogen and fluoride only. The screening levels for chloride,
ammonia nitrogen, and fluoride are calculated using the HERA model.
Table 5.64 Water quality monitoring results for samples Q1–Q3 (Unit: mg/L)
Item
Observed
values
Evaluation
values
Grade III standards
Q1
Q2
Q1
Q2
pH
8.1
7.8
0.733
0.533
6.5–8.5
Total hardness
275
245
0.611
0.544
450
Total soluble solids
308
302
0.308
0.302
1000
Sulfate
20.8
42.5
0.083
0.170
250
Chloride
0.40
0.46
0.002
0.002
250
Iron
0.026
ND
0.087
ND
0.3
Manganese
ND
ND
ND
ND
0.1
Copper
ND
ND
ND
ND
1.0
Zinc
ND
ND
ND
ND
1.0
Volatile phenols
ND
ND
ND
ND
0.002
Permanganate index
1.3
1.6
0.433
0.533
3.0
Nitrate
0.35
0.18
0.018
0.009
20
Nitrite
ND
ND
ND
ND
0.02
Ammonia nitrogen
ND
ND
ND
ND
0.2
Fluoride
0.23
0.09
0.230
0.090
1.0
Cyanide
ND
ND
ND
ND
0.05
Mercury
ND
ND
ND
ND
0.001
Arsenic
ND
ND
ND
ND
0.05
Cadmium
ND
ND
ND
ND
0.01
Chromium (hexavalent)
ND
ND
ND
ND
0.05
Lead
ND
ND
ND
ND
0.05
Selenium
ND
ND
ND
ND
0.01
Anionic synthetic detergents
ND
ND
ND
ND
0.3
5.3 Southwest China
215