Land-use changes in Amazon and Atlantic rainforests modify organic matter and black carbon compositions transported from land to the coastal ocean
Land-use changes in Amazon and Atlantic rainforests modify organic matter and black carbon compositions transported from land to the coastal ocean
复制标题
亚马逊和大西洋雨林的土地利用变化改变了从陆地输送到沿海海洋的有机物和黑碳成分
DOI：
10.1016/j.scitotenv.2023.162917
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发表时间：
2023
影响因子：
9.8
通讯作者：
de Rezende, Carlos Eduardo
中科院分区：
文献类型：
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作者：
Soares Gonçalves Serafim, Tassiana;Gomes de Almeida, Marcelo;Thouzeau, Gérard;Michaud, Emma;Niggemann, Jutta;Dittmar, Thorsten;Seidel, Michael;de Rezende, Carlos Eduardo
本研究评估了南美洲东北部流域沿海沉积物中的黑碳 (BC) 动态、浓度和有机质 (OM) 同位素碳组成。南帕拉伊巴（PSR；巴西大西洋雨林）沿海沉积物显示出比亚马逊和 Sinnamary（法属圭亚那和巴西的亚马逊雨林）沉积物更多的 13 C 富集值（−22.6 ± 1.3 ‰ [n= 13]）（−25.0 ± 3.1 ‰ [n= 14] 和 − 26.1 ± 1.0 ‰ [n= 6]，分别），表明当地土地利用流域的变化改变了有机质的组成，即从天然 C3 植物的贡献到 C4 植物的贡献。对于亚马逊、Sinnamary 和 PSR 样品，归一化为总有机碳 (TOC) 含量的 BC 含量分别为 0.32 ± 0.24 (n= 8)、0.73 ± 0.67 (n= 6) 和 0.95 ± 0.74 (n= 13) mg g−1TOC，BC 来源似乎根据不同流域植被覆盖而有所不同。随着距河口距离的增加，BC含量在沿海地区之间表现出不同的趋势，PSR值增加，亚马逊样本值减少。 Sinnamary 沿海沉积物中的 BC 分布没有表现出特定的模式。对于亚马逊沿海地区，BC 含量下降，但 B6CA:B5CA 比率没有显示出规律，这可能表明该地区的 BC 源自河流运输（老化 BC），并且溶解的 BC 的疏水成分被去除。 BC含量主要在PSR沿海地区增加，而B6CA：B5CA比率在整个梯度中没有改变，表明BC稳定性和可能的烟尘大气沉积。我们的研究结果表明，不同的来源、转化过程和水文条件会影响沿海地区的黑碳含量。亚马逊和大西洋雨林的持续土地覆盖变化可能会导致大规模的海洋碳循环影响。
This study assessed black carbon (BC) dynamics, concentrations, and the organic matter (OM) isotopic carbon composition in northeastern South America drainage basin coastal sediments. Paraíba do Sul (PSR; Atlantic Rainforest, Brazil) coastal sediments displayed more13C-enriched values (−22.6 ± 1.3 ‰ [n= 13]) than Amazon and Sinnamary (Amazon Rainforest in French Guiana and Brazil) sediments (−25.0 ± 3.1 ‰ [n= 14] and − 26.1 ± 1.0 ‰ [n= 6], respectively), indicating that local land-use basin changes have altered the OM composition, i.e., from natural C3plant to C4plants contributions. BC contents normalized to total organic carbon (TOC) content were 0.32 ± 0.24 (n= 8), 0.73 ± 0.67 (n= 6), and 0.95 ± 0.74 (n= 13) mg g−1TOC for Amazon, Sinnamary and PSR samples, respectively, with BC sources appearing to differ according to different drainage basin vegetation covers. With increasing distance from the river mouths, BC contents exhibited different trends between the coastal zones, with values increasing for the PSR and decreasing values for the Amazon samples. BC distribution in Sinnamary coastal sediments did not display specific patterns. Regarding the Amazon coastal zone, BC contents decreased while the B6CA:B5CA ratios did not show a pattern, which could indicate that BC in the area originates from river transport (aged BC) and that the hydrophobic component of dissolved BC is removed. The BC content mostly increased in the PSR coastal zone, while the B6CA:B5CA ratios were not altered for the entire gradient, indicating the BC stability and possible atmospheric deposition of soot. Our findings indicate that different sources, transformation processes, and hydrological conditions affect BC contents within coastal zones. Continuous land cover changes in both the Amazon and Atlantic Rainforests may result in large-scale marine carbon cycling impacts.