Estimation and congener-specific characterization of polychlorinated naphthalene emissions from secondary nonferrous metallurgical facilities in China.

Secondary nonferrous production is addressed as one of the potential sources of the unintentionally produced persistent organic pollutants (UP-POPs) due to the impurity of raw material. Although there are inventories of dioxin emissions from secondary nonferrous metallurgical facilities, release inventories of polychlorinated naphthalenes (PCNs) are scarce. This study selected typical secondary copper, aluminum, zinc, and lead plants to investigate the emissions of PCNs in secondary nonferrous production in China. The toxic equivalency (TEQ) emission factor for PCNs released to the environment is highest for secondary copper production, at 428.4 ng TEQ t(-1), followed by secondary aluminum, zinc, and lead production, at 142.8, 125.7, and 20.1 ng TEQ t(-1), respectively. PCNs released in secondary copper, aluminum, lead, and zinc production in China are estimated to be 0.86, 0.39, 0.009, and 0.01 g TEQ a(-1), respectively. Analysis of stack gas emission from secondary nonferrous production revealed that less-chlorinated PCNs are the dominant homologues, with mono- to tri-CNs making the most important contributions to the concentration. However, for fly ash, the more highly chlorinated PCNs such as octa-CN are the dominant homologues.