Conversion of Forest to Agriculture Increases Colored Dissolved Organic Matter in a Subtropical Catchment and Adjacent Coastal Environment
Conversion of Forest to Agriculture Increases Colored Dissolved Organic Matter in a Subtropical Catchment and Adjacent Coastal Environment
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DOI：
10.1029/2021jg006295
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发表时间：
2021-05
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通讯作者：
S. Felgate;C. Barry;D. Mayor;R. Sanders;Abel Carrias;Arlene Young;A. Fitch;C. G. Mayorga‐Adame;G. Andrews;Hannah Brittain;S. Cryer;C. Evans;Millie Goddard‐Dwyer;J. Holt;Bethany Hughes;D. Lapworth;A. Pinder;D. M. Price;Samir Rosado;C. Evans
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作者：
S. Felgate;C. Barry;D. Mayor;R. Sanders;Abel Carrias;Arlene Young;A. Fitch;C. G. Mayorga‐Adame;G. Andrews;Hannah Brittain;S. Cryer;C. Evans;Millie Goddard‐Dwyer;J. Holt;Bethany Hughes;D. Lapworth;A. Pinder;D. M. Price;Samir Rosado;C. Evans
陆地-海洋溶解有机物（DOM）迁移是全球生态地球化学循环中的一个重要且不断变化的术语，由于人类扰动，包括土地利用变化，DOM迁移正在增加。对迁移DOM的行为和命运的了解还很缺乏，特别是在土地利用变化迅速的热带和亚热带地区。我们使用平行因子（PARAFAC）分析来研究土地利用如何影响中美洲伯利兹亚热带土地利用梯度（从近原始阔叶林到农业城市环境）沿着DOM池的组成。确定了三种腐殖酸样和两种蛋白质样成分，每种成分都存在于土地利用和环境中。土地利用制图确定了阔叶林和农业用地之间的强负相关性（R2 = 0.81）。所有PARAFAC成分与农业-城市土地利用类别（耕地，草地和/或城市土地）呈正相关，表明从森林到农业-城市的土地利用变化对DOM池的组成产生影响。腐殖类DOM随下游距离呈线性积累，在沿海地区表现保守，而蛋白质类DOM在主要河流中呈非线性积累，在沿海沃茨中呈非保守混合，表明反应性存在差异。我们使用了一个水动力学模型，以探讨潜在的保守腐殖酸，以达到该地区的环境和经济价值的珊瑚礁。我们发现，近海珊瑚经历短期暴露（10 ± 11天/年）的大（120%）陆源DOM增加，而近岸珊瑚经历长期暴露（113 ± 24天/年）相对较小（130%）陆源DOM增加。
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 (R2 = 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.