Reference values (mg/kg) and toxicity coefﬁcients (Tr) of heavy metals in sediments.

Table 4: Reference values $C_{n}^{i}$ (mg/kg) and toxicity coefficients ( $T_{r}$ ) of heavy metals in sediments.

Heavy Metals	Cr	Cd	Cu	Zn	Pb
Tr	2	30	5	1	5
ERM	370	9.6	270	410	220
PEL	160	4.2	108	271	112
ERL	81	1.2	34	150	47
TEL	52.3	0.68	18.6	124	30.2
Geochemical background	90	0.3	45	95	20

TEL: Threshold Effect Level; PEL: Probable Effect Level; ERL: Effects Range Low; ERM: Effects Range Median; $C_{n}^{i}$ : Background/ Reference values(mg/kg) and $T_{r}$ : Toxicity Coefficients [22,60].