title: The size distribution of organic carbon in headwater streams in the Amazon basin.
abstract: Despite the strong representativeness of streams in the Amazon basin, their role in the accumulation of coarse particulate organic carbon (CPOC), fine particulate organic carbon (FPOC), and dissolved organic carbon (DOC) in transport, an important energy source in these environments, is poorly known. It is known that the arboreal vegetation in the Amazon basin is influenced by soil fertility and rainfall gradients, but would these gradients promote local differences in organic matter in headwater streams? To answer this question, 14 low-order streams were selected within these gradients along the Amazon basin, with extensions that varied between 4 and 8 km. The efficiency of the transformation of particulate into dissolved carbon fractions was assessed for each stream. The mean monthly benthic organic matter storage ranged between 1.58 and 9.40 t ha(-1) month(-1). In all locations, CPOC was the most abundant fraction in biomass, followed by FPOC and DOC. Rainfall and soil fertility influenced the distribution of the C fraction (p = 0.01), showing differentiated particulate organic carbon (POC) storage and DOC transportation along the basin. Furthermore, the results revealed that carbon quantification at the basin level could be underestimated, ultimately influencing the global carbon calculations for the region. This is especially due to the fact that the majority of studies consider only fine particulate organic matter and dissolved organic matter, which represent less than 50 % of the stored and transported carbon in streambeds.
authors.affiliation: Instituto Nacional de Pesquisas da Amazônia/CPEC-Coordenação de Pesquisas em Ecologia, Av. Efigênio Sales, campus III, Manaus, AM, CEP 69011-970, Brazil. jddpaula@gmail.com.|Universidade Nilton Lins-Coordenação de Pós Graduação em Biologia Urbana, Av. Professor Nilton Lins, 3259, Parque das Laranjeiras, Manaus, CEP 69058-030, Brazil. jddpaula@gmail.com.|Large Scale Program on Biosphere-Atmosphere Interactions in Amazonia - LBA, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Aleixo, campus II, Manaus, CEP 69060-001, AM, Brazil. jddpaula@gmail.com.
authors.forename: Joana D'Arc
authors.initials: JD
authors.lastname: de Paula
authors.affiliation: Large Scale Program on Biosphere-Atmosphere Interactions in Amazonia - LBA, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Aleixo, campus II, Manaus, CEP 69060-001, AM, Brazil.
authors.forename: Flávio Jesus
authors.initials: FJ
authors.lastname: Luizão
authors.affiliation: Coordenação de Pesquisas em Biologia Aquática, Ecology, Monitoring and Sustainable Use of Flooding Areas - MAUA, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Aleixo, campus I, Manaus, CEP 69060-001, AM, Brazil.
authors.forename: Maria Teresa Fernandez
authors.initials: MT
authors.lastname: Piedade
mesh_terms: D001938:Brazil; D002244:Carbon / Q000032:analysis*; D006812:Humic Substances / Q000032:analysis*; D052638:Particulate Matter / Q000032:analysis*; D010568:Peru; D045483:Rivers / Q000737:chemistry*; D013020:South America; D060753:Water Quality
chemical_list: D006812:Humic Substances; D052638:Particulate Matter; D002244:Carbon
keywords: Benthic organic matter; Coarse particulate organic carbon; Dissolved organic carbon; Fine particulate organic carbon; Global carbon cycle; Tropical streams