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

Table 1

Groundwater salinity contamination in various groundwater units in the Pearl River Delta.

Contamination levels	PRD	Unit A	Unit B	Unit C	Unit D
Uncontaminated (%)	78.9	69.4	84.7	84.8	44.5
Low (%)	16.5	26.6	12.4	11.4	11.1
Moderate (%)	3.8	2.4	2.2	3.8	44.4
High (%)	0.8	1.6	0.7	0	0