Natural Background Level and Contamination of Shallow Groundwater Salinity in Various Aquifers in a Coastal Urbanized Area, South China

Table 2

Groundwater salinity contamination in areas with different urbanization levels in the Pearl River Delta.

Contamination levels	PRD			Unit A			Unit B			Unit C
	UA	PUA	NUA	UA	PUA	NUA	UA	PUA	NUA	UA	PUA	NUA
Uncontaminated (%)	70.3	75	90.9	57.4	76.8	81.5	77.3	80.5	97.5	80	68.4	91.8
Low (%)	24.3	18.5	7.0	40.7	18.6	11.1	17	17.1	2.5	12.5	21.1	8.2
Moderate (%)	4.7	5.6	1.4	1.9	2.3	3.7	3.8	2.4	0	7.5	10.5	0
High (%)	0.7	0.9	0.7	0	2.3	3.7	1.9	0	0	0	0	0