Sensitivity of river catchments to discharge-controlled dissolved carbon export: a study of eight catchments in southern Patagonia

Abstract

Understanding the role of catchment sensitivity to dissolved carbon export to aquatic systems is crucial to predict future changes in carbon fluxes under changing climatic conditions. We present 1-year variations in dissolved organic (DOC) and inorganic carbon (DIC) concentrations and fluxes in eight river catchments differing in size (3–300 km2), morphology (steep to flat), and vegetation cover (grassland, forest and peatland) along a precipitation gradient in southern Patagonia, Chile. The results show large differences between catchments in terms of river DOC (2–47 mg L−1; 1–44 tons km−2 year−1) and DIC (0.1–38 mg L−1; 1–5 tons km−2 year−1) concentrations and fluxes in response to changes in discharge. Small and steep catchments hosting organic rich forest soils and peatlands were the most sensitive and showed the highest and fastest DOC release if evaluated on a per unit area basis. Here, rain events caused a rapid exponential increase in DOC release, while DIC export decreased exponentially. A negative correlation between DOC and DIC reveals the minor importance of DIC production through mineralization of DOC in most catchments. Catchments hosting large peatlands had low sensitivity to discharged controlled DOC release attributed to their high hydrological buffer capacity. Similarly, flat and relatively dry Patagonian steppe catchments have comparatively low sensitivity but have short-term high release of DOC accumulated during dry periods. In conclusion, morphology, rather than catchment size or vegetation cover, was found to show the major influence on sensitivity to DOC release.

Small, Coastal Temperate Rainforest Watersheds Dominate Dissolved Organic Carbon Transport to the Northeast Pacific Ocean

“…The range of magnitudes for our modeled watershed DOC yields (1–29 g‐C m −2 yr −1 ; Table 1) agrees with measured DOC yields from our study region including the central coast of British Columbia (24–38 g‐C m −2 yr −1 ; Oliver et al., 2017) and southeast Alaska (11–30 g‐C m −2 yr −1 ; D’Amore et al., 2015), as well as similar coastal temperate rainforest watersheds in Chile (Pérez‐Rodríguez & Biester, 2022; 1–44 g‐C m −2 yr −1 ). Moreover, our yield estimate for southeast Alaska is consistent with recent modeled yields of DOC (6.2 g‐C m −2 yr −1 ; Edwards et al., 2021) and total organic carbon (dissolved + particulate OC; 12.7 g‐C m −2 yr −1 ; Stackpoole, Stets, et al., 2017) for this region, given that particulate organic carbon (POC) can constitute more than 50% of the total riverine OC flux in the glacier‐dominated watersheds found in the region (Bhatia et al., 2013; Hood et al., 2020).…”

Revisiting the Origins of the Power‐Law Analysis for the Assessment of Concentration‐Discharge Relationships

“…For example, in the assessment of multiple base cation C ‐ Q relationships from the Hydrological Benchmark Network the power‐law did not always provide the best fit (Godsey et al., 2009). Yet, there are relatively few examples of log‐linear analyses (i.e., Equation 3) in the C ‐ Q literature, although log‐linear relationships have been used to predict solute fluxes in montane tropical streams (McDowell & Asbury, 1994) and characterize carbon export regimes across catchments in Patagonia (Perez‐Rodriguez & Biester, 2022). The transformation of both concentration and discharge data may not always be appropriate to meet the assumptions of normality given the distribution of the data (McDowell & Asbury, 1994).…”

Fire, volcanism and climate change: the main factors controlling mercury (Hg) accumulation rates in Tropical Lake Lantoa, Sulawesi, Indonesia (∼16,500–540 cal yr BP)

“…The major climatic and environmental processes that influence Hg deposition in lakes include: i) catchment erosion, ii) wet and dry deposition, iii) lake primary productivity, and iv) forest fires (Parkman and Meili, 1992;Lintern et al, 2020;Pérez-Rodríguez and Biester, 2022). Understanding these processes and how they affect HgAR over time is critical to understanding the impacts of anthropogenically-induced environmental and climatic changes on the natural Hg cycle.…”