Application Of Portable X-ray Fluorescence(pXRF)for In Situ Analysis Of Water Polluted By Heavy Metals

Pollution is a serious environmental problem on a global basis,and mining is one of the most major sources of hazardous metals that contaminate soil and water.As a technique of rapid,multi-elemental,nondestructive,and inexpensive analysis,portable X-ray fluorescence spectrum(pXRF)is widely used in the assessment of soil pollution.The relatively high limits of detection(LOD)and the water damage to the instrument are the main factors limit the application of pXRF in water analysis.However,the LOD of ppm level is quite low with respect to the heavy metal concentrations of polluted water.In this research,I attempted to explore the effectiveness of analyzing metal-bearing water in situ using pXRF and quantitatively evaluate influencing factors including the thickness of cling films used for water insulation,the distance between the instrument and solution,and the penetration depth of Xray fluorescence in solution.Through analysis of standard Cu,Pb-bearing solutions prepared in laboratory,it has been found that there was a good correlation between the pXRF readings and the certified concentration values(r2>0.99),and an equation of linear regression was established.The penetration depth of X-ray fluorescence in solution was found to be less than 4 mm in experiment.Finally,a copper mine is chosen as our field research area in which heavy metal-bearing water was produced in the heap leaching process,and based on our samples,the pXRF was effective for ca.80-200 ppm Cu-bearing solution,obtaining excellent correlation(r2>0.95)to the ICP-MS data.Consequently,pXRF is an effective method and has potential for applications in rapid and in situ analysis of water with heavy metal pollution,especially for environmental monitoring during metal ore mining.