Sources and Sinks of Hydroxyl Radicals upon Irradiation of Natural Water Samples
详细信息 查看全文
- 作者：Davide Vione ; Gianpaolo Falletti ; Valter Maurino ; Claudio Minero ; Ezio Pelizzetti ; Mery Malandrino ; Roberto Ajassa ; Romeo-Iulian Olariu ; and Cecilia Arsene
- 刊名：Environmental Science & Technology
- 出版年：2006
- 出版时间：June 15, 2006
- 年：2006
- 卷：40
- 期：12
- 页码：3775 - 3781
- 全文大小：131K
- 年卷期：v.40,no.12(June 15, 2006)
- ISSN：1520-5851
文摘
Hydroxyl radical formation rates, steady-state concentration,and overall scavenging rate constant were measuredby irradiation of surface lake water samples from Piedmont(NW Italy) and nitrate-rich groundwater samples fromMoldova (NE Romania). Dissolved organic matter (DOM)was the main source and sink of 
OH upon lake waterirradiation, with [OH] being independent of DOM amount.Water oxidation by photoexcited DOM is a likely OHsource in the presence of very low levels of nitrate anddissolved iron. Under different circumstances it is not possibleto exclude other processes, e.g., DOM-enhanced photo-Fenton reactions. Under the hypotheses of no interaction andabsence of mutual screening of radiation, nitrate wouldprevail over DOM as OH source for a NO3-/DOM ratio higherthan 3.3 × 10-5 (mol NO3-) (mg C)-1, DOM prevailing forlower values. Substantial DOM photolability was observedupon irradiation of nitrate-rich groundwater, mainly dueto the elevated OH generation rate. For the first time to ourknowledge, evidence was also obtained of the photoformation of potentially toxic and/or mutagenic nitroaromaticcompounds upon irradiation of natural lake water andgroundwater samples, proportionally to the nitrate levels.
OH upon lake waterirradiation, with [OH] being independent of DOM amount.Water oxidation by photoexcited DOM is a likely OHsource in the presence of very low levels of nitrate anddissolved iron. Under different circumstances it is not possibleto exclude other processes, e.g., DOM-enhanced photo-Fenton reactions. Under the hypotheses of no interaction andabsence of mutual screening of radiation, nitrate wouldprevail over DOM as OH source for a NO3-/DOM ratio higherthan 3.3 × 10-5 (mol NO3-) (mg C)-1, DOM prevailing forlower values. Substantial DOM photolability was observedupon irradiation of nitrate-rich groundwater, mainly dueto the elevated OH generation rate. For the first time to ourknowledge, evidence was also obtained of the photoformation of potentially toxic and/or mutagenic nitroaromaticcompounds upon irradiation of natural lake water andgroundwater samples, proportionally to the nitrate levels.