Metal

(mg/L)

Sampling time

Annual average

Standards of environmental protection organization

Spring

Summer

Fall

Winter

Sewage to ground waters

Sewage to absorption wells

Agricultural and irritation usages

Lead

0.157

0.165

0.090

0.120

0.133

1

1

1

Copper

0.210

0.230

0.103

0.098

0.160

1

1

0.2

Nickel

0.293

0.354

0.238

0.205

0.273

2

2

2

Chromium

0.017

0.009

0.009

0.012

0.012

0.5

1

*1

2

2

*2

Zinc

0.070

0.060

0.098

0.049

0.069

2

2

2