Table 2.

Descriptive statistics for the studied variables (TOC, Al, and heavy metals)

	TOC (%)	Al (mg/kg)	Cr (mg/kg)	Ni (mg/kg)	Cu (mg/kg)	Zn (mg/kg)	As (mg/kg)	V (mg/kg)	Pb (mg/kg)	Hg (mg/kg)
Min.	0.29	41,506	72.3	27.74	15.12	46.4	5.86	54.40	16.50	0.02
Max	3.73	67,871	103.0	57.60	83.50	133.0	17.70	95.90	34.46	0.14
Mean	2.47	49,772	83.70	42.53	34.27	84.40	12.49	76.45	26.30	0.06
SD	0.86	4529	7.0	6.45	11.18	16.1	2.99	9.06	4.71	0.02
CV (%)	34.8	9.1	8.3	15.2	32.6	19.1	23.9	11.8	17.9	38.4