Study on the Relationship between Manganese Concentrations in Rural Drinking Water and Incidence and Mortality Caused by Cancer in Huai’an City

Table 2

The comparison of Mn concentrations in drinking water during different periods.

Periods	Water sources		Mean	Std.
High flow period	Surface water	28	437.85	439.79	7.19	0.00
	Shallow groundwater	28	286.56	429.09
	Deep groundwater	28	72.01	130.91
	All	84	265.47	388.83
Low flow period	Surface water	19	607.24	168.38	3.50	0.04
	Shallow groundwater	27	871.35	753.13
	Deep groundwater	28	503.65	406.83
	All	74	664.41	544.82