The initial ultimate bod after mixing of the river is 12.0 mg · l−1. the do in the river after the wastewater and river have mixed is at saturation. the river temperature is 10◦c. at 10◦c, the deoxygenation rate constant (kd) is 0.30 day−1, and the reaeration rate constant (kr) is 0.40 day−1. determine the critical point (tc) and the critical do.

Researchers determine that the biodiversity in a woodland region is declining. they identify two major threats to the region's biodiversity, a method to address each threat, and the expected outcome of each method. this information is shown in the table. a) reforestation would not benefit many species because most forest species live on the ground. b) reforestation would take the longest time to be effective because trees take several years to grow. c) biological augmentation would benefit only a few species because is is typically not very effective. d) biological augmentation would take less time to ve effective because it targets the majority of prey species.