Table 2 Permissible limits for surface waters according to standards of the World Health Organization [38–41], United States Environmental Protection Agency [42–44], and Turkish Standard Institute surface water regulations [45]

As (μg/L)

10^a

50^a

≤20

>100

Ba (μg/L)

700^b

2000^c

≤1000

>2000

Co (μg/L)

–

–

≤10

>200

Cr (μg/L)

50^a

100^a

≤20

>200

Cu (μg/L)

2000^a

1300^a

≤20

>200

Fe (μg/L)

300^a

300^b,c

≤300

>5000

Mn (μg/L)

100^a

50^c

≤100

>3000

Ni (μg/L)

70^a

–

≤20

>200

Pb (μg/L)

10^a

15^a

≤10

>50

Sb (μg/L)

20^b

6^b

–

–

–

–

Zn (μg/L)

3000/1000^a

5000^c

≤200

>2000

Sr (μg/L)

10\(^{\mathrm{c},\mathrm{d}}\)

–

–

–

–

–

a—[41]

a—[44]

b—[39]

b—[43]

c—[38]

c—[42]

d—[40]