Spatial/Temporal Characterization and Risk Assessment of Trace Metals in Mangla Reservoir, Pakistan

Table 2

Descriptive statistics for trace metals (µg/L) and water quality parameters in comparison with national/international guidelines.

	Cd	Co	Cr	Cu	Fe	Mn	Ni	Pb	Zn		pH	TDS	DO
Premonsoon
Mean	36.3	235	75.1	20.3	128	13.1	313	339	31.2	31.6	7.9	92.0	4.3
Median	30.5	231	52.5	16.0	127	10.0	322	241	30.5	31.5	8.1	82.4	4.6
Max	103	501	312	56.0	381	59.0	682	1501	76.0	32.5	8.3	229	4.9
Monsoon
Mean	31.1	157	67.2	14.4	88.5	8.16	126	226	7.84	24.3	7.4	139	6.1
Median	30.5	116	54.0	11.0	66.5	8.00	127	228	5.00	24.4	7.4	131	6.1
Max	53.0	547	194	55.0	278	24.0	415	465	72.0	28.1	7.8	384	6.5
Postmonsoon
Mean	18.3	103	21.0	13.7	109	18.9	124	129	11.7	13.8	6.4	79.4	6.5
Median	17.0	99.0	17.0	12.5	78.5	18.0	116	124	10.5	13.8	6.4	77.0	6.5
Max	40.0	254	63.0	30.0	454	43.0	405	267	31.0	14.2	6.8	139	7.4
Water quality criteria for drinking water
WHO (2008)	3	40	50	2000	300	100	70	10	3000	—	6.5–8.5	1200	—
USEPA (2009), MCL	5		100	1300	300	50	700	15	5000	—	6.5–8.5	500	—
EC (1998)	5		50	2000	200		20	10	100		—	—	—
Pak-EPA (2008)	10		50	2000		500	20	50	5000	—	6.5–8.5	1000	—
Freshwater quality criteria for protection of aquatic life
USEPA (2006), CMC (acute)	2		16	13	1000		470	65	120	—	—	—	—
USEPA (2006), CCC (chronic)	2.5		11	9	1000		52	3		—	—	—	—

: temperature (°C); TDS: total dissolved solids (mg/L); DO: dissolved oxygen (mg/L); CMC: criterion maximum concentration; CCC: criterion continuous concentration.