Kathleen A. Lohse Alison P. Appling Zane K Cram Erin Murray Sarah E. Godsey Steve Van Vactor Emma P McCorkle Mark Seyfried Frederick B Pierson Kayla L Glossner 2022 <div class="abstract-group"><div class="article-section__content en main"><p>Long-term (&gt;20 y) suspended sediment (SS) and particulate organic carbon (POC) records are relatively rare and yet are necessary for understanding linkages between climate, erosion and carbon export. We estimated long-term (&gt;23 y) SS and POC yields from four nested catchments that ranged from &lt;1 to 54 km²<span>&nbsp;</span>in area across the Reynolds Creek Experimental Watershed and Critical Zone Observatory (RCEW-CZO) in southwestern Idaho, USA. We found strong relationships between log₁₀SS and log₁₀POC (R²&nbsp;=&nbsp;0.38–0.86) that varied across catchments but remained robust across years, one dry and one of the wettest water years on record. Mean annual SS yields varied from 18 to 89 g SS m⁻²&nbsp;y⁻¹<span>&nbsp;</span>and POC from 0.6 to 11.0&nbsp;g C m⁻²&nbsp;y⁻¹<span>&nbsp;</span>across the four catchments. Water yield explained much of the temporal variation (72%–85%) in SS and POC yields except in a small, snow-dominated headwater catchment where it explained 15%–51%. The largest five water years accounted for 69%–84% of the total SS and POC yields in catchments with 24 y records. All catchments had positive slopes (&gt;0) for SS and POC concentration-discharge (C-Q) relationships, with large catchments exhibiting greater slopes (0.66–0.97) than smaller ones (0.14–0.16). In addition, most catchments were dominated (80%) by clockwise hysteretic curves. Lack of seasonal exhaustion in the SS-POC relationships, positive C-Q and clockwise relations indicated that these systems were transport-rather than supply limited, and that sediment and POC appeared to be sourced from channel/bank erosion and remobilization. POC yields represent 1%–10% of mean water year net ecosystem exchange depending on elevation; lower elevation catchments may shift from being carbon sinks to sources after accounting for fluvial POC export associated with changes in climate.</p></div></div> application/pdf 10.1002/hyp.14484 en Wiley Long-term suspended sediment and particulate organic carbon yields from the Reynolds Creek Experimental Watershed and Critical Zone Observatory article