Role of dry watercourses of an arid watershed in carbon and nitrogen processing along an agricultural impact gradient
Metadata
Show full item recordEditorial
Elsevier
Materia
Greenhouse gas emissions Nitrate Denitrification Drying-rewetting Dry riverbeds Campo de Cartagena
Date
2023-02-08Referencia bibliográfica
María Isabel Arce... [et al.]. Role of dry watercourses of an arid watershed in carbon and nitrogen processing along an agricultural impact gradient, Journal of Environmental Management, Volume 333, 2023, 117462, ISSN 0301-4797, [https://doi.org/10.1016/j.jenvman.2023.117462]
Sponsorship
Spanish Ministry of Economy and Competitiveness (FJCI- 2015-26192); (IJC 2018-036969-I); aría Zambrano postdoctoral grant by the Spanish Ministry of Universities and Next Generation European UnionAbstract
In the Mediterranean arid region such as Southeast (SE) Spain, a considerable part of the fluvial network runs
permanently dry. Here, many dry watercourses are embedded in catchments where agriculture has brought
changes in carbon (C) and nitrogen (N) availability due to native riparian vegetation removal and the establishment
of intensive agriculture. Despite their increasing scientific recognition and vulnerability, our knowledge
about dry riverbeds biogeochemistry and environmental drivers is still limited, moreover for developing proper
management plans at the whole catchment scale. We examined CO2 and N2O emissions in five riverbeds in SE
Spain of variable agricultural impact under dry and simulated rewetted conditions. Sediment denitrifying capacity
upon rewetting was also assessed. We found that, regardless of agricultural impact, all riverbeds can emit
CO2 under dry and wet conditions. Emissions of N2O were only observed in our study when a long-term rewetting
driving saturated sediments was conducted. Besides, most biogeochemical capabilities were enhanced in summer,
reflecting the sensitiveness of microbial activity to temperature. Biogeochemical processing variation across
rivers appeared to be more controlled by availability of sediment organic C, rather than by agriculturally derived
nitrate. We found that the studied dry riverbeds, agriculturally affected or not, may be active sources of CO2 and
contribute to transitory N2O emissions during rewetting phenomena, potentially through denitrification. We
propose that management plans aiming to support ecosystem biogeochemistry through organic C from native
vegetation rather than agricultural exudates would help to reduce anthropogenic greenhouse gases emissions and
excess of nutrients in the watershed and to control the nitrate inputs to coastal ecosystems.