Hot-Soda Process Paper Mill Effluent Effects on Fishes and Macroinvertebrates in the Narayani River, Nepal

Abstract

ABSTRACT Although the effects of effluent from many paper production processes have been studied extensively, the effects of hot-soda process effluent have not been investigated. To determine the impacts of this process on a riverine ecosystem in Nepal, we sampled fishes, macroinvertebrates, and physicochemical/microhabitat parameters of the Narayani River in south-central Nepal upstream and downstream from the Bhrikuti Paper Mill before and after its opening. After the mill began operation, species richness of fish collections decreased downstream, relative to the upstream reference site. We also found a decrease in abundance of macroinvertebrates, as well as a downstream decrease in dissolved oxygen and an increase in alkalinity. Changes in benthic microhabitat were also apparent, including an increase in plant fiber detritus. Our results suggest that the environmental impact of this untreated soda-process effluent is similar to that of effluent from other paper production processes, and that operation of such mills can have a negative impact on riverine ecosystems.