CO₂ efflux from Amazonian headwater streams represents a significant fate for deep soil respiration

Abstract

[1] Large Amazonian rivers are known to emit substantial amounts of CO 2 to the atmosphere, while the magnitude of CO 2 degassing from small streams remains a major unknown in regional carbon budgets. We found that 77% of carbon transported by water from the landscape was as terrestrially-respired CO 2 dissolved within soils, over 90% of which evaded to the atmosphere within headwater reaches of streams. Hydrologic transport of dissolved CO 2 was equivalent to nearly half the gaseous CO 2 contributions from deep soil (>2 m) to respiration at the soil surface. Dissolved CO 2 in emergent groundwater was isotopically consistent with soil respiration, and demonstrated strong agreement with deep soil CO 2 concentrations and seasonal dynamics. During wet seasons, deep soil (2 -8 m) CO 2 concentration profiles indicated gaseous diffusion to deeper layers, thereby enhancing CO 2 drainage to streams. Groundwater discharge of CO 2 and its subsequent evasion is a significant conduit for terrestrially-respired carbon in tropical headwater catchments. Citation: Johnson, M. S.,

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

“…Besides lake productivity, other factors are thought to influence the metabolism and partial pressure of CO 2 (pCO 2 ) in the surface waters of lakes, such as temperature, dissolved organic carbon concentration, and dissolved inorganic carbon inputs from the watershed (e.g. Hanson et al, 2003;Johnson et al, 2008;Kosten et al, 2010). Lake's pCO 2 is then the result of the interaction of many factors and the extent to which each factor controls CO 2 likely varies among systems and across time scales.…”

Effects of agricultural land use on fluvial carbon dioxide, methane and nitrous oxide concentrations in a large European river, the Meuse (Belgium)

“…Groundwater can be a source of GHGs to riverine systems in particular in lower order streams and headwaters (Johnson et al, 2008;Hotchkiss et al, 2015). The comparison of CO 2 and CH 4 in groundwater and riverine waters of the Meuse basin (Fig.…”

A system for environmental monitoring of hydroelectric reservoirs in Brazil

“…The acquisition of meteorological data is also important for water quality monitoring since the intensity of precipitation events determines runoff intensity and the transport of organic and inorganic elements from the soils to the aquatic ecosystems (Johnson et al 2008). In this way, changes in the intensity and frequency of precipitation may contribute to higher input of nutrients and consequently enhance the eutrophication process.…”