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

Abstract

Hydrogen peroxide (H2O2) formation rates (nM h−1), photoproductive capacity (nM W−1 h−1 m−2), and H2O2 formation efficiency (ϕH2O2) 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 H2O2 formation rates and DOC was a power function (H2O2 = 49.65 DOC1.71; r2 = 0.94), whereas the relationships between formation rates and DOC fluorescence (DOCFL) (H2O2 = 118.32 + 33.06 DOCFL; r2 = 0.98) and absorption coefficients at 310 (Ka310) were linear (H2O2 = 185.0 + 55.50 Ka310; r2 = 0.91). ϕH2O2 was independent of DOC (r2 = 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.