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Conversion of Forest to Agriculture Increases Colored Dissolved Organic Matter in a Subtropical Catchment and Adjacent Coastal Environment
Author(s) -
Felgate Stacey L.,
Barry Christopher D. G.,
Mayor Daniel J.,
Sanders Richard,
Carrias Abel,
Young Arlene,
Fitch Alice,
MayorgaAdame Claudia G.,
Andrews Gilbert,
Brittain Hannah,
Cryer Sarah E.,
Evans Chris D.,
GoddardDwyer Millie,
Holt Jason T.,
Hughes Bethany K.,
Lapworth Dan J.,
Pinder Adam,
Price David M.,
Rosado Samir,
Evans Claire
Publication year - 2021
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2021jg006295
Subject(s) - dissolved organic carbon , environmental science , terrigenous sediment , subtropics , land use , grassland , biogeochemical cycle , land use, land use change and forestry , organic matter , ecology , hydrology (agriculture) , geology , structural basin , biology , paleontology , geotechnical engineering
Land‐ocean dissolved organic matter (DOM) transport is a significant and changing term in global biogeochemical cycles which is increasing as a result of human perturbation, including land‐use change. Knowledge of the behavior and fate of transported DOM is lacking, particularly in the tropics and subtropics where land‐use change is occurring rapidly. We used Parallel Factor (PARAFAC) Analysis to investigate how land‐use influenced the composition of the DOM pool along a subtropical land‐use gradient (from near‐pristine broadleaf forest to agri‐urban settings) in Belize, Central America. Three humic‐like and two protein‐like components were identified, each of which was present across land uses and environments. Land‐use mapping identified a strong ( R 2 = 0.81) negative correlation between broadleaf forest and agri‐urban land. All PARAFAC components were positively associated with agri‐urban land‐use classes (cropland, grassland, and/or urban land), indicating that land‐use change from forested to agri‐urban exerts influence on the composition of the DOM pool. Humic‐like DOM exhibited linear accumulation with distance downstream and behaved conservatively in the coastal zone whilst protein‐like DOM exhibited nonlinear accumulation within the main river and nonconservative mixing in coastal waters, indicative of differences in reactivity. We used a hydrodynamic model to explore the potential of conservative humics to reach the region's environmentally and economically valuable coral reefs. We find that offshore corals experience short exposures (10 ± 11 days yr −1 ) to large (∼120%) terrigenous DOM increases, whilst nearshore corals experience prolonged exposure (113 ± 24 days yr −1 ) to relatively small (∼30%) terrigenous DOM increases.