NO₂ (mg/l)

NO₃ (mg/l)

DO (mg/l)

PH

Research

2

2

4

1

Abrahão et al., 2007

3

4

1

Boyacioglu, 2007

4

4

Chougule et al., 2009

4

4

Dwivedi and Pathak, 2007

2

2

4

1

Kannel et al., 2007

2

2

4

1

Karakaya and Evrendilek, 2009

4

4

Pathak and Banerjee, 1992

2

2

4

1

Pesce and Wunderlin, 2000

2

2/2

4

2/1

Mean