Scholarlink

<p>The stable isotopes of rainfall (δ<sup>18</sup>O, δ<sup>2</sup>H or δD) are important tracers of hydrological and climatological processes. However, the isotopic data remain sparse in tropical regions. This study presents a comprehensive isotopic characterization of rainfall in Cameroon. It is based on 224 monthly samples collected between 2012 and 2015 from 13 stations spanning diverse climatic and ecological zones. The main objectives were to evaluate spatial and seasonal variations, their controlling factors, establish local meteoric water lines (LMWLs), and the first Cameroon meteoric water line (CmrMWL). The results revealed wide variations (δ<sup>1</sup>⁸O: -9.49 to + 3.86‰, δD: -65.56 to + 38.61‰, d-excess: 1.18‰ to 21.37‰). Isotopically enriched values were observed in low-altitude coastal areas, while depleted signatures dominated high-altitude inland locations, indicating an altitude effect, though with a weak correlation (R<sup>2</sup> = 0.19). Similarly, the latitude effect was weak (R<sup>2</sup> = 0.06), and d-excess showed no strong correlation with altitude (R<sup>2</sup> = 0.08) or latitude. However, elevated d-excess values (&gt; &gt;+ 10‰) across both lowland and highland areas suggested significant contributions of precipitation from recycled continental moisture sources, particularly from the dense rainforests and inland water bodies. Strong negative correlations between monthly isotopes and rainfall depths marked the “amount effect.” Isotopic variability in Cameroon is shaped by the combined influence of regional factors (latitude, proximity to the coast) and local controls (altitude, vegetation, and seasonality). However, local climatic and seasonal dynamics tend to obscure the expected isotopic gradients. The slopes of LMWLs were similar to that of the Global Meteoric Water Line (GMWL), suggesting equilibrium conditions, while deviations in the semi-arid north reflected evaporation effects. Complemented by literature data, the first CmrMWL, δD = 8.12δ<sup>1</sup>⁸O + 13.83 (R<sup>2</sup> = 0.97, <i>n</i> = 383), exhibited a slope similar to that of the GMWL but with a higher intercept, highlighting the role of recycled moisture. Despite the uneven spatial coverage, the results provide baseline data for environmental studies and underscore the need for long-term monitoring to enhance water resource management in Cameroon and other tropical regions.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Spatial and temporal variations of stable isotopes in precipitation and its controlling factors across Cameroon: Local, regional and the first Cameroon meteoric water lines

  • 期刊论文

  • 发表日期：

    2025年11月3日

查看全文
  • Mengnjo Jude Wirmvem,
  • Aïcha Foupouagnigni,
  • Engome Regina Wotany,
  • Wiylahnyuy Edith Kongnso,
  • Mumbfu Ernestine Mimba,
  • Muga Yaguchi,
  • Brice Tchakam Kamtchueng,
  • Justice Yuven Suila,
  • Gloria Eneke Takem,
  • Wilson Yetoh Fantong,
  • Ako Andrew Ako,
  • Samuel Ndonwi Ayonghe,
  • Takeshi Ohba

摘要

The stable isotopes of rainfall (δ18O, δ2H or δD) are important tracers of hydrological and climatological processes. However, the isotopic data remain sparse in tropical regions. This study presents a comprehensive isotopic characterization of rainfall in Cameroon. It is based on 224 monthly samples collected between 2012 and 2015 from 13 stations spanning diverse climatic and ecological zones. The main objectives were to evaluate spatial and seasonal variations, their controlling factors, establish local meteoric water lines (LMWLs), and the first Cameroon meteoric water line (CmrMWL). The results revealed wide variations (δ1⁸O: -9.49 to + 3.86‰, δD: -65.56 to + 38.61‰, d-excess: 1.18‰ to 21.37‰). Isotopically enriched values were observed in low-altitude coastal areas, while depleted signatures dominated high-altitude inland locations, indicating an altitude effect, though with a weak correlation (R2 = 0.19). Similarly, the latitude effect was weak (R2 = 0.06), and d-excess showed no strong correlation with altitude (R2 = 0.08) or latitude. However, elevated d-excess values (> >+ 10‰) across both lowland and highland areas suggested significant contributions of precipitation from recycled continental moisture sources, particularly from the dense rainforests and inland water bodies. Strong negative correlations between monthly isotopes and rainfall depths marked the “amount effect.” Isotopic variability in Cameroon is shaped by the combined influence of regional factors (latitude, proximity to the coast) and local controls (altitude, vegetation, and seasonality). However, local climatic and seasonal dynamics tend to obscure the expected isotopic gradients. The slopes of LMWLs were similar to that of the Global Meteoric Water Line (GMWL), suggesting equilibrium conditions, while deviations in the semi-arid north reflected evaporation effects. Complemented by literature data, the first CmrMWL, δD = 8.12δ1⁸O + 13.83 (R2 = 0.97, n = 383), exhibited a slope similar to that of the GMWL but with a higher intercept, highlighting the role of recycled moisture. Despite the uneven spatial coverage, the results provide baseline data for environmental studies and underscore the need for long-term monitoring to enhance water resource management in Cameroon and other tropical regions.