Parameter Unit 2010 2011 Standard1 Influent Effluent Influent Effluent Temperature °C 25.3 (25.1−25.9) 25.4 (24.3−26.9) 26.4 (20.9−29.9) 26.0 (21.9−30.1) n.a. Salinity ppt 41.5 (39.0−44.0) 44.2 (30.0−52.0) 18.38 (0.0−32.5) 16.7 (0,0−35.0) 0.5−30.0 pH   7.7 (7.6−7.9) 8.0 (8.0−8.1) 6.9 (6.3−7.9) 7.0 (6.5−7.6) 6.0−9.0 DO mg/L 4.7 (4.6−4.9) 8.2 (6.0−10.2)* 5.2 (2.6−7.4) 8.7 (5.0−15.4)* >4.0 TAN mg/L 0.55 (0.01−1.55) 2.55 (1.15−3.50)* 1.57 (0.01−1.31) 2.35 (0.95−3.25)* ≤ 0.40 Ammonia mg/L 0.01 (0.0−0.01) 0.20 (0.04−0.47)* 0.02 (0.0−0.2) 0.14 (0.07−0.22)* n.a. Nitrate mg/L 0.5 (0.5−0.6) 1.1 (1.0−1.5)* 0.3 (0.2−0.5) 0.9 (0.6−1.5)* ≤ 0.40 Nitrite mg/L 0.01 (0.0−0.01) 0.04 (0.03−0.05)* 0.02 (0.0−0.05) 0.04 (0.1−0.07)* ≤ 0.07 Total phosphorus mg/L 0.08 (0.06−0.09) 0.20 (0.11−0.40)* 0.08 (0.01−0.20) 0.20 (0.10−0.31)* ≤ 0.12 Chlorophyll a µg/L 1.5 (1.0−2.0) 30.0 (15.0−45.0)* 1.8 (1.0−4.0) 15.2 (8.0−21.0)* ≤ 30.0 BOD mg/L 1.2 (0.4−2.1) 8.4 (3.0−13.9)* 3.7 (1.4−6.3) 12.7 (4.7−25.0) n.a. Turbidity NTU 1.5 (1.0−2.0) 37.5 (4.0−62.0)* 7.0 (4.0−13.0) 11.7 (6.0−18.0) n.a.

Na: Not Available; 1CONAMA (Brazilian National Environment Council) Resolution number 357 of March 17, 2005 (Brazilian water quality standard for industrial effluents discharged into brackish water). *Significant differences between Influent and effluent for each year studied. Table 3: Characteristics of the influent and effluent from shrimp ponds in the Coreaú river estuary.