DOI: 10.1002/2015GB005095
Scopus记录号: 2-s2.0-84955201394
论文题名: Terrestrial pyrogenic carbon export to fluvial ecosystems: Lessons learned from the White Nile watershed of East Africa
作者: Güereña D ; T ; , Lehmann J ; , Walter T ; , Enders A ; , Neufeldt H ; , Odiwour H ; , Biwott H ; , Recha J ; , Shepherd K ; , Barrios E ; , Wurster C
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2015
卷: 29, 期: 11 起始页码: 1911
结束页码: 1928
语种: 英语
英文关键词: black carbon
; fire
; slash and burn
; soil carbon
; soil organic matter
; watershed
Scopus关键词: agricultural land
; baseflow
; biogeochemical cycle
; black carbon
; carbon flux
; catchment
; concentration (composition)
; fire
; fluvial process
; forest ecosystem
; gauge
; global change
; learning
; organic carbon
; shifting cultivation
; soil carbon
; soil organic matter
; streamwater
; suspended sediment
; terrestrial environment
; total organic carbon
; transport process
; upland region
; watershed
; East African Lakes
; Kenya
; Lake Victoria
; Sudan
; White Nile
英文摘要: Pyrogenic carbon (PyC) is important because of its role in the global organic C (OC) cycle and in modifying soil properties. However, our understanding of PyC movement from terrestrial to fluvial ecosystems is not robust. This study examined (i) whether erosion or subsurface transport was more important for PyC export from headwaters, (ii) whether PyC was exported preferentially to total OC (TOC), and (iii) whether the movement of PyC from terrestrial to aquatic ecosystems provides an explanation for the coupling of PyC and non-PyC observed in rivers at a global scale. In the Guineo-Congolian highland forest region of western Kenya, duplicate catchments with sizes of 1-12 ha were equipped with stream gauges in primary forest and adjacent mixed agricultural landscapes that were cleared by fire 10, 16, or 62 years before. Stream water samples were taken weekly throughout 1 year and compared with runoff to assess PyC movement. Additional stream samples were taken from all major tributaries of the White Nile watershed of Lake Victoria. PyC was not found to be preferentially eroded relative to TOC or non-PyC, as topsoil (0-0.15 m) PyC concentrations (6.3 ± 0.3% of TOC; means and standard errors) were greater than runoff sediment (1.9 ± 0.4%) and dissolved PyC concentrations (2.0 ± 0.4%, n = 252). In addition, PyC proportions in eroded sediment were lower than and uncorrelated (r2 = 0.04; P = 0.14) with topsoil PyC. An enrichment of PyC was found with depth in the soil, from 6.3 ± 0.3% of TOC in the topsoil (0-0.15 m) to 12.3 ± 0.3% of TOC at 1-2 m. Base flow PyC proportions of TOC correlated well with subsoil PyC (r2 = 0.57; P < 0.05) but not with topsoil PyC (r2 = 0.18; P > 0.05). Similar PyC proportions were found in the studied headwater streams (2.7 ± 0.2%), their downstream inflow into Lake Victoria (3.7%), the other nine major rivers into Lake Victoria (4.9 ± 0.8%), and its outflow into the White Nile (1.1%). A strong positive correlation between dissolved PyC and non-PyC (r2 = 0.91; P < 0.0001) in the headwater streams reflect relationships previously seen for a range of globally important rivers, and contrasts with a negative relationship for suspended sediments (r2 = -0.5; P < 0.0001). The estimated PyC export from the Lake Victoria watershed of 11 Gg yr-1 may therefore originate to a large extent from subsoil pathways in dissolved form that appeared to be an important source of PyC in aquatic environments and may explain the coupling of PyC and non-PyC at a global scale. © 2015. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77906
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Crop and Soil Sciences, Cornell University, Ithaca, NY, United States; Atkinson Center for A Sustainable Future, Cornell University, Ithaca, NY, United States; Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, United States; World Agroforestry Centre (ICRAF), Nairobi, Kenya; International Livestock Research Institute, Nairobi, Kenya; College of Science, Technology and Engineering James Cook University, Townsville, QLD, Australia; Centre for Tropical Environmental and Sustainability Sciences, James Cook University, Townsville, QLD, Australia
Recommended Citation:
Güereña D,T,, Lehmann J,et al. Terrestrial pyrogenic carbon export to fluvial ecosystems: Lessons learned from the White Nile watershed of East Africa[J]. Global Biogeochemical Cycles,2015-01-01,29(11)