... ocean 320 million tons of Fe; 2.3 million tons of Pb; 1.6 million tons of Mg; 320 million tons of Ca; Phosphate 6.5 million tons, 10 million tons of oil; and 700 tons of Hg (The National Centre ... Current situation of Da River Left-bank Industrial Zone’s wastewater 41 4.2.1.1 Situation of wastewater of Da River Left-bank Industrial Zone in 2013 41 v 4.2.1.2 Situation of wastewater ... 35 million km3 of wastewater annually, of which there are 4,000 tons of acids, 1,300 tons of caustic soda, 300 tons of benzene, 25 tons of organic materials and other substances that contaminated...