Using catchment characteristics to model seasonality of dissolved organic carbon fluxes in semi-arid mountainous headwat

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Using catchment characteristics to model seasonality of dissolved organic carbon fluxes in semi-arid mountainous headwaters Kazem Nosrati

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Adrian L. Collins & Peter Fiener

Received: 4 June 2020 / Accepted: 20 September 2020 # Springer Nature Switzerland AG 2020

Abstract Prediction of dissolved organic carbon (DOC) based on catchment characteristics is a useful tool for efficient and effective water management, but in the case of arid and semi-arid regions, such predictive capacity is scarce. Accordingly, the main objective of this study was to evaluate the significance of principal components for predicting DOC concentrations and fluxes in nine headwater catchments of the Hiv catchment located in the Southern Alborz Mountains in the west of Tehran, Iran. To achieve this aim, data were assembled on 24 headwater catchment characteristics comprising soil properties, physiography, seasonal rainfall, and flow attributes, as well as estimates of DOC concentrations and fluxes across four seasons. The results revealed a major positive correlation between DOC and soil organic matter parameters related to soil biological processes. Using general linear modelling, an organic matter component related to soil biology, a seasonal component related to the dummy effect of sampling seasons, and a soil physical component related

K. Nosrati (*) Department of Physical Geography, Faculty of Earth Sciences, Shahid Beheshti University, Tehran 1983969411, Iran e-mail: [email protected] A. L. Collins Sustainable Agriculture Sciences Department, Rothamsted Research, North Wyke, Okehampton EX20 2SB, UK P. Fiener Water and Soil Resources Research, Institut für Geographie, Universität Augsburg, Augsburg, Germany

to soil texture were found to be the best predictors for DOC responses in the study area. Keywords Organic matter . Soil enzyme activities . Modelling . Headwater catchments . General linear model

Introduction Lateral organic carbon fluxes from land into inland waters and ultimately oceans are of growing interest in unravelling the global carbon (C) cycle (Brunet et al. 2009; Janeau et al. 2014; Raymond et al. 2013). Accordingly, these were explicitly addressed within the latest scientific report of the IPCC (IPCC 2007), wherein, carbon reaches the atmosphere indirectly as DOC (Wohl et al. 2017). Organic carbon delivery from catchments into inland waters results mostly from erosioninduced redistribution of particle bound or particulate carbon and from dissolved organic carbon fluxes via surface runoff, interflow, and groundwater transport (Manninen et al. 2018; Wang et al. 2014, 2017). Evaluation of the effect of anthropogenic (accelerated) soil erosion on C fluxes, based on a comprehensive global database, showed that erosion processes on agricultural land have had an enormous impact on the C cycle and during the period 6000 BC to AD 2015, the net absorption of C in terrestrial landscapes has therein increased by about 78 Pg C (Wang et al. 2017). The effect of soil erosion on the global C cycle has been extensively debated f