Analysis on the Causes for Arsenic Enrichment of Deep Groundwater in Costal Tangshan

摘要

In some coastal area of Tangshan,38.5% of the water samples of As from deep groundwater exceed the limit of Quality standard for ground water,10ug/L, and excessive water samples mainly from continued pumping water wells of living water. Continued field pumping water for As testing, we found that arsenic concentrations continued to rise as the pumping time, steady about 24 hours later and declined gradually after the pumping stopped. By the hypothetic-deductive method, we rule out the possibility of man-made pollution. By means of correlation analysis, principal component analysis and other means identify the connection of arsenic and carbonic acid balance,as well as Fe,and draw on previous results properly verified by experiments this time for the analysis. Finally we found dynamic changes concentrations of arsenic caused by the pumping of the deep groundwater,resulting in the rise on Eh in wells which lead to the transform between Fe (OH)_2 and Fe (OH)_3.The differences of their adsorption capacity may be the significant factor accounting for the dynamic changes of arsenic concentration in the relatively open groundwater system.