Premium
Comparison of Changes in Metal Toxicity Following Exposure of Water with High Dissolved Organic Carbon Content to Solar, UV‐B and UV‐A Radiation
Author(s) -
Winch Susan,
Lean David
Publication year - 2005
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2005-05-29-ra-552
Subject(s) - dissolved organic carbon , chemistry , absorbance , environmental chemistry , irradiation , metal , total organic carbon , metal toxicity , toxicity , carbon fibers , nuclear chemistry , heavy metals , chromatography , materials science , physics , organic chemistry , composite number , nuclear physics , composite material
This study examines the effects of natural solar radiation on the metal‐binding capacity of dissolved organic matter (DOM). Newington Bog water (35.5 mg L −1 dissolved organic carbon [DOC]) was irradiated for 20 days under UV‐B lamps in the laboratory and under natural solar radiation. In the presence of irradiated DOM, IC 50 (contaminant concentration required to reduce algal growth by 50%) was significantly decreased with UV‐B treatment for four metals: Pb, 64%; Cu, 63%; Ni, 35% and Cd, 40%. Solar radiation also significantly decreased IC 50 of Pb (58%) and Cu (49%), DOC concentration (11%), DOM fluorescence (DOMFL, 33%) and DOC‐specific UV absorbance. Further experiments on Raisin River water (20.7 mg DOC L −1 ) exposed to 20 days of artificial UVA and UV‐B radiation produced significant decreases in IC 50 for Cu (48%) with UV‐A and for Pb (43%) with UV‐B. DOC concentration was decreased 20% by UV‐B and 24% by UV‐A. DOMFL decreased 51.5% in the first 5 days of UV‐A exposure, an effect that was not observed with the UV‐B treatment. The UV‐A treatment decreased UV absorbance more at longer wavelengths and over a broader wavelength band than did the UV‐B treatment. Change in toxicity with UV irradiation was inconsistent among the metals tested in this study, indicating that some organic metal‐binding ligands were more quickly removed or altered than others. The DOM remaining after irradiation appears to be qualitatively different from the unirradiated DOM. The much greater irradiance of UV‐A makes its contribution to the removal and/or alteration of DOM at least as important as the influence of higher energy UV‐B.