Hydrogen peroxide formation: The interaction of ultraviolet radiation and dissolved organic carbon in lake waters along a 43–75°N gradient

Abstract

Abstract-Hydrogen peroxide (H,O,) formation rates (nM h-l), photoproductive capacity (nM W-l h-l m-*), and H202 formation efficiency (bH202) were measured on water samples exposed to a standard light source with a spectral composition similar to natural sunlight. Samples were from lakes and wetlands with varying levels of dissolved organic C (DOC), P, Fe, Ca, and pH. The relationship between H,O, formation rates and DOC was a power function @ItO = 49.65 DOC1-71; r* = 0.94), whereas the relationships between formation rates and DOC fluorescence (DOCFLJ w202 = 118.32 '+ 33.06 DOCm, r* = 0.98) and absorption coefficients at 3 10 (J&,) were linear (H202 = 185.0 + 55.50 Kaslo; r* = 0.9 1). +H202 was independent of DOC (r* = 0.12). Apparent quantum yields decreased with increasing wavelengths (300-400 nm). However, when apparent quantum yields were corrected with solar irradiance data, values were greatest in the UV-A (320-400 nm) region. The patterns observed were consistent for samples from temperate to arctic regions.

Photochemical production of hydrogen peroxide and methylhydroperoxide in coastal waters

“…For samples other than the Elizabeth River, there is no statistically significant relationship between peroxide production and [DOC]. Scully et al (1996) observed a power relationship between H 2 O 2 production and DOC content in freshwaters, similar to that observed for the Elizabeth River sample. Whether relationships of this type should be extended to seawater systems is still unclear.…”

“…H 2 O 2 production in Elizabeth River water was similar to that of freshwater systems, such as Lake Ontario (160-1473 nM h À 1 ) and other temperate lakes (695-2120 nM h À 1 ) (Scully et al, 1996). Surface waters with substantial terrigenous run-off influence exhibited the greatest production of both H 2 O 2 and MHP, with the majority of production occurring at wavelengths less than 320 nm.…”

“…Given the proposed mechanism for H 2 O 2 production, where the photochemical production is initiated by CDOM photon absorption, one would expect a relationship between H 2 O 2 production and CDOM. Many freshwater systems exhibit relationships between DOC content and/or absorbance, and H 2 O 2 production (Scully et al, 1996). For our experiments, predominantly using surface seawaters, there is no clear relationship between H 2 O 2 production and the mass-specific absorbance [a* (m 2 Ag (Fig.…”

“…A number of studies have determined the photochemical production of H 2 O 2 in freshwater and ground waters (Cooper et al, 1988, Scully et al, 1996. Zuo and Hoigne (1992) examined the formation of H 2 O 2 in atmospheric water that results from iron(III)-oxalato complex photolysis.…”

Photodegraded dissolved organic matter from peak freshet river discharge as a substrate for bacterial production in a lake-rich great Arctic delta

“…Because DOM is an important component of carbon budgets in aquatic ecosystems, an understanding of how photodegradation alters DOM bioavailability is critical to understand carbon fluxes through the landscape. In contrast to the positive effects of increased substrate availability on bacterial metabolism, photodegradation also exerts indirect negative effects on aquatic bacteria through the production of free radicals and reactive oxygen species (ROS) (e.g., singlet oxygen, peroxides, and superoxides) (Scully et al 1996). These by-products of the photodegradation process are short-lived, but nevertheless inhibit bacterial growth and production (Lund and Hongve 1994;Henle and Linn 1997;Anesio et al 2005).…”