Photochemical Characterization of Surface Waters from Lakes in the Adirondack Region of New York

Abstract

The Adirondack Mountain region of New York, a historical hotspot for atmospheric sulfur and nitrogen deposition, features abundant lakes that are experiencing browning associated with recovery from acidification. Yet, much remains unknown about the photoreactivity of Adirondack lake waters. We quantified the apparent quantum yields (Φ app,RI ) of photochemically produced reactive intermediates (RIs), such as excited triplet states of dissolved organic matter ( 3 DOM*), singlet oxygen ( 1 O 2 ), and hydroxyl radicals ( • OH), for surface waters collected from 16 representative Adirondack lakes. Φ app, 3 DOM* and Φ app, 1 O 2 for native Adirondack lake waters fell within ranges reported for whole waters and DOM isolates from various sources, while Φ app, • OH were substantially lower than those measured for other aquatic samples. Orthogonal partial least squares and multiple linear regression analyses identified the spectral slope coefficient from 290 to 400 nm (S 290−400 ) as the most effective predictor of Φ app,RI among measured water chemistry parameters and bulk DOM properties. Φ app,RI also exhibited divergent responses to controlled pH adjustment and aluminum or iron addition simulating hypothetical scenarios relevant to past and future water chemistry conditions of Adirondack lakes. This study highlights the need for continued research on changes in photoreactivity of acid-impacted aquatic ecosystems in response to browning and subsequent impacts on photochemical processes.

Photogeneration of Reactive Species from Biochar-Derived Dissolved Black Carbon for the Degradation of Amine and Phenolic Pollutants

“…19,25 In addition, the rate constant of a one-electron-transfer reaction between 3 DBC* and TMP was estimated as ∼9.3 × 10 8 M −1 s −1 in this study, which is generally higher than those of reference NOM samples. 44,54 Thus, compared with many well-studied DOM, 3 DBC* with high one-electron oxidation capacity is likely to be a more efficient sensitizer for photodegradation of selected PPCPs, with rate constants in the range of (0.4−1.7) × 10 9 M −1 s −1 determined in this study. Moreover, the • OH formed from DBC also participated in the degradation and accounted for ∼18% in the removal of propylparaben.…”

“…26 Thus, the triplet lifetime in air-saturated solutions was estimated as 3.97 ± 0. NOM* with TMP (∼8.5 × 10 8 M −1 s −1 ) under similar reaction conditions and the measuring method, 44 which suggested that 3 DBC* has a stronger capacity for oneelectron-transfer TMP oxidation. This result agrees with the finding of a previous study that 3 DBC* exhibited a higher TMP quantum yield coefficient (f TMP ) than 3 NOM*.…”

“…13 The quantum yield of 3 DBC* (Φ 3 DBC* , measured with TMP) was calculated as an average value of 4.8% (Table 1), which is also greater than that of 3 NOM* (∼2.8%). 44 Therefore, the higher quantum yield and electron-transfer capacity of 3 DBC* can give rise to more rapid triplet-sensitized degradation of PPCPs in the DBC-containing waters. 1 O 2 and • OH were captured by TEMP and DMPO using ESR spin trap experiments, respectively (Figures 2a,c and S8).…”

Changes in acidity, DOC, and water clarity of Adirondack lakes over a 30-year span

“…During recovery, the chronically acidified lakes exhibited large declines in mono-Al which were accompanied by increased DOC, CDOM and light attenuation. Recent laboratory studies have documented the inhibitory effect of Al under acidic conditions on the formation of photoreactive forms of DOM (Wasswa et al 2020). DOC-specific light absorption increased by twofold indicating that the proportional contribution of CDOM increased at a faster rate than for DOC.…”

Coupling Suspect and Nontarget Screening with Mass Balance Modeling to Characterize Organic Micropollutants in the Onondaga LakeThree Rivers System

“…PNA was analyzed by an Agilent 1260 Infinity II high-performance liquid chromatograph with a variable wavelength detector. 46 For each OMP, the depth-dependent photolysis rate constants in the epilimnion of Onondaga Lake, k OMP_epi (d -1 ), were approximated as:…”