Table 2.

Concentration of cadmium, lead and mercury in muscle of fish collected from water reservoirs of Chihuahua County in different seasons ¹.

Water Reservoirs	Species	Sampling Season	Cadmium (mg/kg Wet Weight)	Lead (mg/kg Wet Weight)	Mercury (mg/kg Wet Weight)
El Rejón	Channel catfish	Spring	0.061 ± 0.013a	2.327 ± 0.080b	0.041 ± 0.022
		Summer	0.235 ± 0.013b	<0.042a	0.039 ± 0.022
		Autumn	<0.0025a	3.154 ± 0.080c	0.059 ± 0.022
		Winter	<0.0025a	<0.042a	0.047 ± 0.022
	Green sunfish	Spring	0.027 ± 0.014	1.718 ± 0.560a,b	<0.005a
		Summer	<0.0025	<0.042a	0.098 ± 0.012b
		Autumn	<0.0025	3.516 ± 0.560b	0.059 ± 0.012a,b
		Winter	<0.0025	<0.042a	0.034 ± 0.012a,b
Chihuahua	Channel catfish	Spring	<0.0025	0.729 ± 0.103b	<0.005a
		Summer	0.010 ± 0.007	<0.042a	0.047 ± 0.010a,b
		Autumn	0.024 ± 0.007	2.110 ± 0.103c	0.042 ± 0.010a,b
		Winter	<0.0025	<0.042a	0.089 ± 0.010b
	Green sunfish	Spring	<0.0025	2.746 ± 0.087b	<0.005a
		Summer	0.121 ± 0.055	<0.042a	0.465 ± 0.256b
		Autumn	<0.0025	1.525 ± 0.087b	<0.005a
		Winter	<0.0025	<0.042a	<0.005a
San Marcos	Blue gill	Spring	<0.0025a	0.623 ± 0.329	0.744 ± 0.119
		Summer	0.036 ± 0.0004b	<0.042	0.333 ± 0.119
		Autumn	<0.0025a	0.976 ± 0.329	0.395 ± 0.119
		Winter	<0.0025a	<0.042	0.275 ± 0.119
Chuviscar	Channel catfish	Spring	0.090 ± 0.005b	4.298 ± 0.626b	<0.005
		Autumn	<0.0025a	<0.042a	0.013 ± 0.004
		Winter	<0.0025a	<0.042a	<0.005

Notes: ¹ Expressed as least squares means ± standard error of mean; n = 46; < Below the detection limit of analytical technique; ^{a, b, c} = Different letters in column show statistical differences at a 0.05 confidence level according to the ANOVA and Tukey tests.