Trace Metal Content of Sediments Close to Mine Sites in the Andean Region

Table 2

Metal concentration (mg/kg) in sediment samples with grain size < 63 μm for tributaries of Rejo subbasin with median, mean, standard deviation and skew for R1, R2, and R3 (mainstream points), threshold effect level (TEL), and probable below level (PEL).

	R1	R2	R3	R4	Median^a	Mean^a	SD^a	Skew^a	TEL	PEL
pH	—^c	—	—	—	—	—	—	—	—	—
EC^b	37	—	32	—	34.5	34.5	—	—	—	—
AI	15605	13574.6	9601.9	14330.4	13575	12927	3053.5	−0.9	—	—
As	55.93	63.3	48.78	56.82	55.9	56	7.3	0.0	5.9	17
Cd	12.3	4.5	5.4	3.1	5.4	7.4	4.3	1.6	0.6	3.5
Cr	3.3	7.6	4.8	6.7	4.8	5.2	2.2	0.9	37.3	90
Cu	198	34.4	42.8	16.6	42.8	91.7	92.1	1.7	35.7	197
Fe	15360.1	16810.3	15261	14731.7	15360.1	15810	867.3	1.7	—	—
Hg	0.1	0.17	0.1	0.09	0.1	0.12	0.0	1.7	0.17	0.49
Mn	3711.8	878.6	932.2	349.9	932.2	1841	1620.5	1.7	—	—
Ni	12	11.8	7	6.4	11.8	10.3	2.8	−1.7	—	—
Pb	92.6	54.7	40.5	47.9	54.7	62.6	26.9	1.2	35	91
Sb	n.d.^d	n.d.	n.d.	n.d.	—	—	—	—	—	—
Sn	76.3	79.7	62.8	87.5	76.3	72.9	8.9	−1.5	—	—
Zn	452.7	122.2	149.9	55.3	149.9	241.6	183.3	1.7	123	315

^aCalculated for mainstream samples (R1, R2, R3); ^bOhms*1000; ^cno available; ^dno detectable (n.d.).