Event based high resolution measurement of DOC-concentration and quality in a rural headwater catchment
Abstract. The export of dissolved organic carbon (DOC) from small river systems is a significant factor in the global carbon cycle. DOC quality can be used to identify the sources of carbon in headwater systems. High-resolution in-situ measurements in small headwater catchments can unveil fast changing patterns of DOC export and DOC quality during events. In this study, the influence of precipitation events on DOC export and changing DOC quality was analyzed using highly resolved discharge and DOC concentration and quality data of 5-minute time steps. Data analysis was conducted using spearman correlation analysis, hysteresis analysis and visual comparison of pre-event and event conditions. Measurements took place from January 2021 until August 2022 in a German lower mountain catchment with predominantly agricultural land use. While DOC export was lower than in other catchments the DOC quality followed a well-observed seasonal pattern and was significantly influenced by the antecedent wetness of the catchment and the length of precipitation events. The results showed that the use of in-situ high resolution measurements can provide a detailed insight into the DOC export dynamics of a catchment and can help to identify the most important drivers of DOC quality changes.
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