Analysis on the Influencing Factors of Iron and Manganese Content in
Shallow Groundwater in the Water Source-Area near the Feng River in
Xi'an
Abstract
Iron and manganese ions, as the main contribution indicator of
super-class Ⅲ shallow groundwater in the western suburbs of Xi’an,
seriously threaten the safety of local water supply and the health of
residents. Based on data collection and hydrogeological survey, this
paper studies the concentration of iron and manganese in groundwater by
collecting and analyzing 52 groups of groundwater samples, and analyzes
the possible sources of iron and manganese in consideration of human
factors such as hydrogeological conditions and surface pollution input.
The results showed: (1) The highest iron content exceeded the Class Ⅲ
water quality standard by 1.03 times, and the highest manganese content
exceeded the Class Ⅲ water quality standard by 3.92 times. The water
sample points exceeding Class Ⅲ accounted for 9.5% and 26.2% of the
total water sample points respectively. (2) The content of iron and
manganese in the water of Feng River is 8.47% and 19.69% of the
groundwater respectively. Therefore, the higher iron and manganese in
individual wells near the source of Feng River have no obvious
relationship with Feng River. (3) According to drilling data, the iron
and manganese content in different rock masses is silty
clay>round gravel>fine sand, medium-coarse
sand, and the distribution of iron and manganese content is positively
correlated. (4) In the experiment of the iron and manganese release law
in the rock mass, it was observed that the iron and manganese in the
overlying water experienced three stages of rapid increase, fall and
stabilization. When the final release stabilizes, the release rate of
manganese in the rock mass is higher than that of iron. The manganese
content in the overlying water is 0.010~0.057mg/L, the
release rate is 0.02%~0.05%, and the iron content is
0.004~0.023mg/ L, the release rate is less than 0.01%,
and the higher pH in the water environment has a significantly higher
inhibitory effect on the release of iron in the rock mass than
manganese.