Investigation of Water Leakage of Metro Segments Caused by Metro Underpass Structures

Table 4

Main indicators of water composition analysis.

Composition
Item	SO4^2−(mg/L)	Mg^2+ (mg/L)	Total salinity (mg/L)	pH	CO2 (mg/L)	Cl^−(mg/L)
Instrument and equipment	Conical flask, pipette, burette, volumetric flask, acidity meter and matching compound electrode, evaporating dish
Reagent	HCl solution, EDTA-2 Na solution, solution of Ba and Mg	Ammonium buffer solution, chromium black solid indicator, Na2S solution	1% Na2CO3 solution	Standard buffer solution, saturated KCl solution	CaCO3 powder, indicator, Na2CO3 solution, HCl solution	K2CrO4 indicator, NaCl solution, AgNO3 solution
Method	Volumetric method	EDTA-2Na complexometric titration	Weight method	Acidometer titration	Acid-base titration	AgNO3 volumetric method
Leakage section	84.50	274.87	1418	6.44	11.31	722.62
Phreatic water	10.96	13.45	149	7.26	3.51	23.13
Confined water	72.45	226.38	5094	6.63	7.02	2838.23