Comparing on the chemic features of the ground water in and around the Jinfoshan Natural Reserve in Chongqing

In light of the hydrochemical monitoring data of 22 groundwater discharge points, the differences of the hydrochemic features and the impact factors of the ground water in and around the Jinfoshan natural reserve, Chongqing is compared in the article. The results show that the pH values of the springs outside the reserve are lower than those inside, but the conductivity is higher. The median concentration of Ca2+, Mg2+, Na+, K+, Cl-, NO3-, SO42- and HCO3- around the reserve are respectively 27.78 mg/L, 3.23 mg/L, 3.47 mg/L, 0.97 mg/L, 2.38 mg/L, 9.29 mg/L,15.06 mg/L and 42.03 mg/L higher than those inside the natural reserve. The Mg2+/Ca2+ (mole ratio) in dolomite aquifer is 0.76~1.33, obviously higher than that in limestone or clastic rock aquifer. But in the same limestone aquifer the Mg2+/Ca2+ around the reserve is higher than those inside. The results indicate that GSICa2+ is 0.097, GSIHCO3- is 0.125, GSINO3- is 0.008 in the reserve, and GSICa2+ is 0.415, GSIHCO3- is 0.334, GSINO3- is 0.648 around the reserve. The water quality of the reserve is mostly grade I andⅡ. But affected by agricultural fertilization, industrial pollution and sewage discharge, the springs water outside the reserve isⅢ andⅤ,and the NO3- concentration is higher in springs N0.1, NO.16 and NO.19. Over all, the water quality inside the reserve is significantly better than the outside. It can clearly be seen that the establishment of natural reserves has positive significance for karst water protection.