Methane concentrations and fluxes in agricultural and preserved tropical headwater streams

Taniwaki, Ricardo Hideo; Cunha, Daví Gasparini Fernandes; Bento, Camila Bolfarini; Martinelli, Luiz Antônio; Stanley, Emily H.; Filoso, Solange; Ferreira, M.; França, Marcus Vinícius; Júnior, José Wagner Ribeiro; Schiesari, Luís; Carmo, Janaína Braga do

doi:10.1016/j.scitotenv.2022.157238

Cited by 5 publications

(1 citation statement)

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“…CH 4 concentration data from agricultural streams in the tropics are scarce. In a sugarcane‐dominated catchment of Brazil, streamwater CH 4 concentrations were lower compared to forest, which was attributed to the lower OC loading from the agricultural land‐use (i.e., lower DOC and POC inputs; Taniwaki et al., 2022). In this study, the higher relative OC loading combined with the higher probability of anoxia within the streambed of the Ag site likely explains the difference from the study in Brazil.…”

Section: Resultsmentioning

confidence: 99%

Agricultural Land‐Use Increases Carbon Yields in Lowland Streams of the Congo Basin

Drake,

Baumgartner,

Barthel

et al. 2024

JGR Biogeosciences

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As the dominant mode of deforestation in the Congo Basin, shifting agriculture is expected to increase with the projected four‐fold population growth for the region by 2,100. To assess how this land‐use change will affect the export of carbon (C) to rivers in a typical lowland forest ecosystem, we studied paired watersheds near Kisangani, Democratic Republic of the Congo. Two streams, one draining an intact forest (Forest) and one draining an agricultural landscape (Ag), were gauged, equipped with sensors, and sampled fortnightly for one year. Annual average specific discharge was 1.4 mm d−1 (+76%) higher in the Ag compared to the Forest. Average annual dissolved organic C (DOC) and particulate organic C (POC) concentrations were 5.2 mg L−1 (+163%) and 1.3 mg L−1 (+81%) higher in the Ag stream, which, along with the higher discharge, resulted in 8.3 (+410%) and 2.4 g C m−2 yr−1 (+97%) larger C yields, respectively. Baseflow dissolved inorganic carbon, carbon dioxide, and methane yields were also higher in the Ag stream. Despite the higher yields of organic C (OC), the composition of OC did not differ significantly. Carbon to nitrogen ratios, along with isotopic signatures, revealed that both streams contained young, semi‐degraded organic matter derived from C3 vegetation. Correspondingly, biodegradable DOC (BDOC) proportions did not differ between the streams, although the Ag stream yielded more total BDOC. These results show that agricultural land‐use likely exports a greater proportion of Net Primary Productivity (NPP) to aquatic ecosystems, which may affect both C storage in soils and the proportion of gross PP that is ultimately respired.

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Section: Resultsmentioning

confidence: 99%