Reanalysis of spring water and its pollution causes of the Niangziguan spring in Shanxi

As one of the largest karst spring in North China, the Niangziguan spring in Shanxi well known one in the world, with an average annual natural flux of 12.6 m3/s. This work was based on the 1∶50，000 project of hydrogeology and environmental geology investigation to this spring and adjacent areas. The purpose was to reanalyze the two issues,(1) The genesis of the Niangziguan spring water；(2) The causes of its pollution. Exploration data show that the Wulong and Weizeguan springs, located at the south bank of the Mianhe river, mainly receive the recharge of karst water from the middle and upper Cambrian water-bearing formation rather than the recharge karst water from the upper middle Ordovician to lower Ordovician aquifers as suggested by previous studies. In combination with hydrogeological conditions, analysis of isotopes considers that part of the coal mine gob water flow is the primary cause for accelerating pollution of the spring in recent years.