Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil
Systems rich in terrigenous dissolved organic carbon (DOC), like the Rio Negro, can contribute significant amounts of carbon dioxide back to the atmosphere and support important microbial communities. We investigated photo-oxidation in the Rio Negro: (1) the depth to which light causes complete phot...
| Autor principal: | Johannsson, Ora E. |
|---|---|
| Outros Autores: | Ferreira, Márcio Soares, Smith, David Scott, Crémazy, Anne, Wood, Chris M., Val, Adalberto Luis |
| Grau: | Artigo |
| Idioma: | English |
| Publicado em: |
Science of the Total Environment
2020
|
| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/23244 |
| id |
oai:repositorio:1-23244 |
|---|---|
| recordtype |
dspace |
| spelling |
oai:repositorio:1-23244 Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil Johannsson, Ora E. Ferreira, Márcio Soares Smith, David Scott Crémazy, Anne Wood, Chris M. Val, Adalberto Luis Carbon Dioxide Fluorophores Microorganisms Organic Carbon Stream Flow Water Resources Dissolved Organic Carbon Fluorophore emission Humic-acid-like Light exposure Microbial communities Natural light Natural sunlight Rate of change Oxidation Carbon Dioxide Dissolved Organic Carbon fluorochrome Humic Acid Organic Carbon Unclassified Drug Dissolved Organic Carbon Diurnal Variation Factor Analysis Fluorescence Light Effect Photooxidation Water Depth Absorption Brazil Carbon Footprint Carbonization Chemical Analysis Chemical Structure Controlled Study depth perception Dry Season Fluorescence light adaptation Light exposure Light Intensity Microbial Community Photooxidation photoreactivity Priority Journal rainy season River Ecosystem Seasonal Variation Sunlight Surface Property ultraviolet radiation Rio Negro [south America] Systems rich in terrigenous dissolved organic carbon (DOC), like the Rio Negro, can contribute significant amounts of carbon dioxide back to the atmosphere and support important microbial communities. We investigated photo-oxidation in the Rio Negro: (1) the depth to which light causes complete photo-oxidation to CO2 and changes in DOC structure, (2) the daily rate of change of absorbance indices, (3) the relationship between sub-surface rates of photo-oxidation to CO2 and light exposure, (4) the areal rates of photo-oxidation, and (5) the stability of fluorophore signals. Experiments were run in an outdoor pool of Rio Negro water, under natural sunlight during the dry seasons of 2015 and 2018. In 2018, rates of complete photo-oxidation and changes in absorbance indices decayed exponentially, approaching their asymptotes between 9 and 15 cm depth. In 2015, direct absorbance indices ceased changing at 14 cm depth. Fluorescence of humic acid-like moieties continued to decrease, sometimes to 35–43 cm depth. This indicates that partial photo-oxidation of DOC, and thus interaction with the microbial community, occurs to greater depths than previously expected. Areal rates of CO2 production were 28.8 and 39.3 mg C m−2 d−1 (two experiments, October 2018). Sub-surface (1.1 cm) rates were strongly related to light levels, reaching a maximum of 0.68 mg C l−1 d−1 in September. Complete photo-oxidation ceased below 29.6 mW cm−2 d−1 UV radiation, providing a daily baseline for observable production of CO2. Absorbance indices changed by 9 to 14% d−1 at high light levels, except for R254/365 (4.4% d−1). Fluorophore emission ranges were stable between 2014 and 2018, indicating that emissions can be compared across time and space. This study contributes to better estimates and understanding of photo-oxidation in tropical, black-water rivers, which will be useful for carbon modelling. © 2020 Elsevier B.V. 2020-07-03T21:06:29Z 2020-07-03T21:06:29Z 2020 Artigo https://repositorio.inpa.gov.br/handle/1/23244 10.1016/j.scitotenv.2020.139193 en Volume 733 Attribution-NonCommercial-NoDerivs 3.0 Brazil http://creativecommons.org/licenses/by-nc-nd/3.0/br/ Science of the Total Environment |
| institution |
Instituto Nacional de Pesquisas da Amazônia - Repositório Institucional |
| collection |
INPA-RI |
| language |
English |
| topic |
Carbon Dioxide Fluorophores Microorganisms Organic Carbon Stream Flow Water Resources Dissolved Organic Carbon Fluorophore emission Humic-acid-like Light exposure Microbial communities Natural light Natural sunlight Rate of change Oxidation Carbon Dioxide Dissolved Organic Carbon fluorochrome Humic Acid Organic Carbon Unclassified Drug Dissolved Organic Carbon Diurnal Variation Factor Analysis Fluorescence Light Effect Photooxidation Water Depth Absorption Brazil Carbon Footprint Carbonization Chemical Analysis Chemical Structure Controlled Study depth perception Dry Season Fluorescence light adaptation Light exposure Light Intensity Microbial Community Photooxidation photoreactivity Priority Journal rainy season River Ecosystem Seasonal Variation Sunlight Surface Property ultraviolet radiation Rio Negro [south America] |
| spellingShingle |
Carbon Dioxide Fluorophores Microorganisms Organic Carbon Stream Flow Water Resources Dissolved Organic Carbon Fluorophore emission Humic-acid-like Light exposure Microbial communities Natural light Natural sunlight Rate of change Oxidation Carbon Dioxide Dissolved Organic Carbon fluorochrome Humic Acid Organic Carbon Unclassified Drug Dissolved Organic Carbon Diurnal Variation Factor Analysis Fluorescence Light Effect Photooxidation Water Depth Absorption Brazil Carbon Footprint Carbonization Chemical Analysis Chemical Structure Controlled Study depth perception Dry Season Fluorescence light adaptation Light exposure Light Intensity Microbial Community Photooxidation photoreactivity Priority Journal rainy season River Ecosystem Seasonal Variation Sunlight Surface Property ultraviolet radiation Rio Negro [south America] Johannsson, Ora E. Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil |
| topic_facet |
Carbon Dioxide Fluorophores Microorganisms Organic Carbon Stream Flow Water Resources Dissolved Organic Carbon Fluorophore emission Humic-acid-like Light exposure Microbial communities Natural light Natural sunlight Rate of change Oxidation Carbon Dioxide Dissolved Organic Carbon fluorochrome Humic Acid Organic Carbon Unclassified Drug Dissolved Organic Carbon Diurnal Variation Factor Analysis Fluorescence Light Effect Photooxidation Water Depth Absorption Brazil Carbon Footprint Carbonization Chemical Analysis Chemical Structure Controlled Study depth perception Dry Season Fluorescence light adaptation Light exposure Light Intensity Microbial Community Photooxidation photoreactivity Priority Journal rainy season River Ecosystem Seasonal Variation Sunlight Surface Property ultraviolet radiation Rio Negro [south America] |
| description |
Systems rich in terrigenous dissolved organic carbon (DOC), like the Rio Negro, can contribute significant amounts of carbon dioxide back to the atmosphere and support important microbial communities. We investigated photo-oxidation in the Rio Negro: (1) the depth to which light causes complete photo-oxidation to CO2 and changes in DOC structure, (2) the daily rate of change of absorbance indices, (3) the relationship between sub-surface rates of photo-oxidation to CO2 and light exposure, (4) the areal rates of photo-oxidation, and (5) the stability of fluorophore signals. Experiments were run in an outdoor pool of Rio Negro water, under natural sunlight during the dry seasons of 2015 and 2018. In 2018, rates of complete photo-oxidation and changes in absorbance indices decayed exponentially, approaching their asymptotes between 9 and 15 cm depth. In 2015, direct absorbance indices ceased changing at 14 cm depth. Fluorescence of humic acid-like moieties continued to decrease, sometimes to 35–43 cm depth. This indicates that partial photo-oxidation of DOC, and thus interaction with the microbial community, occurs to greater depths than previously expected. Areal rates of CO2 production were 28.8 and 39.3 mg C m−2 d−1 (two experiments, October 2018). Sub-surface (1.1 cm) rates were strongly related to light levels, reaching a maximum of 0.68 mg C l−1 d−1 in September. Complete photo-oxidation ceased below 29.6 mW cm−2 d−1 UV radiation, providing a daily baseline for observable production of CO2. Absorbance indices changed by 9 to 14% d−1 at high light levels, except for R254/365 (4.4% d−1). Fluorophore emission ranges were stable between 2014 and 2018, indicating that emissions can be compared across time and space. This study contributes to better estimates and understanding of photo-oxidation in tropical, black-water rivers, which will be useful for carbon modelling. © 2020 Elsevier B.V. |
| format |
Artigo |
| author |
Johannsson, Ora E. |
| author2 |
Ferreira, Márcio Soares Smith, David Scott Crémazy, Anne Wood, Chris M. Val, Adalberto Luis |
| author2Str |
Ferreira, Márcio Soares Smith, David Scott Crémazy, Anne Wood, Chris M. Val, Adalberto Luis |
| title |
Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil |
| title_short |
Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil |
| title_full |
Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil |
| title_fullStr |
Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil |
| title_full_unstemmed |
Effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the Rio Negro, Brazil |
| title_sort |
effects of natural light and depth on rates of photo-oxidation of dissolved organic carbon in a major black-water river, the rio negro, brazil |
| publisher |
Science of the Total Environment |
| publishDate |
2020 |
| url |
https://repositorio.inpa.gov.br/handle/1/23244 |
| _version_ |
1787143787725717504 |
| score |
11.755432 |