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Cyanide and mercury level determination in small scale mining areas in the Philippines

Jinky Leilanie Lu

Free cyanide and totalmercury concentrationswere measured fromthe 196 water samples collected from the different water sources - rivers, dams, creeks, springswithin the vicinity of 40 small scalemining areas in Benguet, Philippines which is the largest mining area in the northern Philippines. Ninety-eight water samples each were subjected for free cyanide and total mercury analysis.While none of the water samples exceeded the maximum limit for free cyanide, there were 90 water samples (92%) had positive readings. The average reading of all the samples of cyanide analysis was 0.047ppm(s.d. 0.0098).While 83%of the water sampleswere positive with mercury, only twenty-nine percent exceeded the standard. Themean reading of all the positive results ofmercurywas 0.064ppb (s.d.0.061).The source of mercury and cyanide residues found can be due to historic and current mining operations in the tenmunicipalities and also to thewidespread smallmining operations in the province as a source of livelihood of the people.