Photodegradation of polychlorinated naphthalene in mixtures.

Solutions of technical polychlorinated naphthalene (PCN) Halowax formulations (Halowax 1014 and Halowax 1051) diluted with Milli-Q water and sealed in the Pyrex glass tubes and quartz tubes were subjected to artificial solar and natural solar irradiation under different time intervals and field conditions. In particular, the results of several field irradiation experiments have shown increased PCN photodegradation as altitude increases above sea level. Irradiation in artificial solar conditions caused a substantial change in the PCN congener profiles of Halowax 1014 and Halowax 1051 test solutions. Interestingly, in long-term experiments, the relative abundance of congeners that contribute to dioxin-like activity, i.e. the compounds such as 1,2,3,5,7- and 1,2,4,6,7-PentaCN (PeCNs #52/60), 1,2,3,4,6,7- and 1,2,3,5,6,7-HexaCN (HxCNs #66/67), and 1,2,3,4,5,6,7-HeptaCN (HpCN #73), temporally increased substantially. In the field photodegradation experiments, the PCNs #52/60 and #66/67 were formed, while a relative persistence of PCN #73 was evident. Highest chlorinated octachloronaphthalene (OcCN #75), exposed to strong UV radiation at high altitude, was much less stable than lower molecular mass PCNs. Photodegradation of the technical PCN formulations produced also an unidentified aromatic compound. We conclude, that photodegradation of PCNs, which are considered as a widespread anthropogenic pollutants, is not restricted to any specific environmental condition. It can also be observed at low altitudes. Image 1 • Halowax 1014 and 1051 photodegrade with yield in a few most persistent CNs. • Most toxic PCNs are also formed from a higher molecular mass PCN. • Photodegradation of PCNs accelerate as altitude increases above sea level. • Photodegradation of PCNs is not restricted to any specific environmental condition. • Unidentified aromatic compound was photoproduct from degraded PCNs. Photodegradation of polychlorinated naphthalene is not restricted to any specific environmental condition, while increases with altitude above sea level. A dioxin-like active 1,2,3,5,7- and 1,2,4,6,7-PentaCN (PeCNs #52/60), 1,2,3,4,6,7- and 1,2,3,5,6,7-HexaCN (HxCNs #66/67), and 1,2,3,4,5,6,7-HeptaCN (HpCN #73) are temporally abundant products of photodegradation of higher chlorinated congeners. [ABSTRACT FROM AUTHOR]