Environmental pollution (1987), 2021-03, Vol.272, p.116412-116412, Article 116412
2021
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- Autor(en) / Beteiligte
- Titel
- Optical properties and 14C ages of stream DOM from agricultural and forest watersheds during storms
- Ist Teil von
- Environmental pollution (1987), 2021-03, Vol.272, p.116412-116412, Article 116412
- Ort / Verlag
- Elsevier Ltd
- Erscheinungsjahr
- 2021
- Quelle
- ScienceDirect
- Beschreibungen/Notizen
- Forest and agricultural land use affects the concentration and composition of dissolved organic carbon (DOC) in streams and rivers. To elucidate the impacts of forest and agricultural land use on stream DOC during storm events, we investigated DOC concentration ([DOC]), optical properties of dissolved organic matter (DOM), and Δ14C-DOC in both forest- and agriculture-dominated headwater streams in South Korea in the summer of 2012. One forested and five agricultural streams were investigated. During storms, the peak [DOC] of forest stream increased to 5.8 mg L−1, approximately two times larger than that of the most agricultural stream (3.2 mg L−1), demonstrating the weaker storm responses of the [DOC] of agricultural streams to hydrological change. Five PARAFAC components were identified, including three terrestrial humic-like substances (C1, C2, C3), one microbial humic substance (C4), and one microbial protein-like substances (C5). The mean (C4+C5)/(C1+C2+C3) of all storm events at the most agricultural stream was 1.5 times larger than that of the most forested stream, suggesting that more protein-like DOM is exported from agricultural watersheds. Whereas a forest stream was primarily composed of terrestrially derived and 14C-enriched modern DOC, the 14C-age of the most agricultural stream was up to ∼1000 years old. The results suggest that agricultural practices could decrease the old organic carbon pools from soils. However, how quickly the aged DOC can be degraded to CO2 in streams is unknown, warranting future investigation on lability of the aged DOC and their effects on CO2 evasion from rivers and estuaries downstream. [Display omitted] •Agricultural watersheds release more protein-like materials to streams compared to forested watersheds during storms.•Relatively old DOC was released from an agricultural watershed to a stream during storms.•Agricultural practices could reduce the pool of stable soil organic carbon. Stream DOM from agricultural watershed is older and more protein-like substances than that from forest watersheds during storms.