Progress 07/01/24 to 06/30/25
Outputs
Target Audience: Private industry professionals responsible for designing and constructing stream and floodplain restorations. University researchers, faculty, students, and extension personnel. Federal, state, and local governments Nonprofit environmental organizations Changes/Problems:The only key change that has happened is the delay in the removal of Roller milldam - our primary study site addressing Question 2 on this project. The delay has been associated with funding and other logistical challenges associated with removal of the 12 ft dam. We expect that this dam removal will occur in 2026. If not, we will seek other dam removal sites to address the hypotheses posed under question 2. What opportunities for training and professional development has the project provided?This study has been very valuable for professional development of postdoc Dr. Eric Moore who was funded on this project. While Eric was the only person directly funded on the project he was assisted by numerous research group members for sampleing and data analysis. Three PhD students - Alexis Yaculak, Bisesh Joshi and Matthew Sena, and two other postdocs - Moklesur Rahman and Joe Galella also assisted with the sediment sampling. The project has also been important for the professional development of the PIs - Shreeram Inamdar, Jinjun Kan, and Marc Peipoch and their lab managers Laura Borecki. How have the results been disseminated to communities of interest?Results have been disseminated by submitting work to journals as well as presenting the findings at conferences and other meetings with stakeholders and government agencies. Manuscript in review: Moore et al. (In review). Dams and their legacies sahpe riparian soil evolution. Science Advances (In review). Conference and meeting Presentations: Moore, E. et al. Evolution of Riparian Terrace Sediments Following Dam Removal and Soil Drainage. 2024 AGU Fall Meeting. Washington, DC, December 9-13, 2024. Moore et al. 2025. Regional ESA Meeting at Longwood Gardens, Evondale, PA. April 2025. What do you plan to do during the next reporting period to accomplish the goals?We plan to complete the microbial manuscript and submit it to a top microbial ecology journal by July 2025. The removal of the Roller milldam has been delayed until 2026. Question 2 addressed the immediate changes in sediment characteristics post removal. Hence, we will have to wait for this sampling and anlaysis until this dam removal. We will however also lookout for other potential dam removals that could replace this site to expedite the results on this project.
Impacts
What was accomplished under these goals?
All riparian terrace sampling upstream of dams to address Q1 has been completed. The physicochemical analysis and interpretation of the sediment results was completed, a manuscript was drafted and is currently in review with Science Advances (submitted April 2025). The microbial community analysis and interpretation is currently in progress and we intend to submit the manuscript to a top refereed journal by July 15, 2025. Key details are provided below. Twelve riparian sites with three existing and nine previously breached/removed milldams were selected across three watersheds in the mid-Atlantic region of the US (Table 1). Streams/watersheds sampled included the Chiques Creek, Big Elk Creek, and Christina River. Milldam breach/removal dates, along with location coordinates, sampled terrace depths, drainage watershed area at the dam location, and SSURGO soil types in the immediate proximity are presented in Table 1. Milldam State Latitude Longitude Stream Sampled Depth (m) Year Breached & age Drainage area (km2) SSURGO Soil Type Heistand PA 40.0553 -76.5268 Chiques 2.13 2015 (9) 326.34 Lindside-Linden complex Johnston PA 40.0634 -76.5154 Chiques 1.22 1926 (98) 279.72 Lindside silt loam Krady PA 40.0689 -76.4998 Chiques 2.74 2018 (6) 162.13 Lindside-Linden complex Siegrist PA 40.0749 -76.4685 Chiques 2.74 Existing 153.85 Hagerstown silty clay loam Roller PA 40.1083 -76.4431 Chiques 3.35 Existing 127.43 Hagerstown silt loam Shenck PA 40.1165 -76.4239 Chiques 1.52 1954* (70) 108.26 Hagerstown silt loam White Oak PA 40.2060 -76.3943 Chiques 2.13 1972 (52) 47.40 †Bowmansville silt loam Parks MD 39.6751 -75.8288 Big Elk 3.96 1935 (89) 125.36 Hatboro-Codorus complex Scott MD 39.6889 -75.8272 Big Elk 3.96 1935 (89) 122.25 Hatboro-Codorus complex Springlawn PA 39.7389 -75.8671 Big Elk 3.96 1958* (66) 81.58 Codorus silt loam Cooch DE 39.6456 -75.7424 Christina 3.35 existing 49.73 Hatboro-Codorus complex Old Cooch DE 39.6415 -75.7371 Christina 2.13 1790 (234) 49.99 Hatboro-Codorus complex Sediment sampling was conducted between April and May 2024. One sediment core was collected 100 - 300 m upstream from the milldam locations using a manual auger (3.5 cm diameter), approximately 2-5 m from the stream bank. Sediment cores were collected to refusal when possible, and the augered depth varied from 1.2 m - 4 m (Table 1). However, a shovel was used to collect surface soils at two sites (Cooch, Old Cooch) where augering was difficult due to high sand content, and at another site (Springlawn) sediment samples were collected from the stream bank face (after scraping away exposed soil with a hand trowel) due to difficulty with augering on the riparian terrace. Sediment/soil samples were collected for each auger cylinder (i.e., every 0.3 m), placed into labeled Ziplock bags, and preserved on ice until they could be refrigerated in the lab. RESULTS (summary): Our results revealed that sediment/soil physical and chemical characteristics: (a) changed considerably with riparian depth and time post dam removal/breach; (b) some metrics displayed a more pronounced change than others; and (c) soil metrics evolved asynchronously. Soil NH4+, NO3-, FeM3, Feo, and ripeness revealed strong patterns with depth and time; TOC, TN, and BD, were not as pronounced but followed expectations, while Fec changes did not conform to our expectations. Also, while the overall patterns of change were similar for the Chiques and Christina-Big Elk creek watersheds, there were key differences in the rates of change of individual metrics between the drainage basins. Differences in the rates of change for sediment metrics could suggest important differences in the processes and kinetics and the factors responsible. Riparian GW levels before and after dam breach/removal and associated redox conditions appeared to be a primary regulator for these changes. Secondarily, sediment/soil evolution pre and post drainage was also likely shaped by soil textural differences, organic matter contents, and the presence of the relict, pre-dam floodplain soil horizon. We elaborate on these spatiotemporal patterns and the factors responsible in the discussion below. Understanding these changes and the drivers involved will advance the science of pedogenesis, allow for development of new paradigms for soil evolution, and provide a better assessment of human impacts on riparian ecosystems. This study highlighted that physicochemical characteristic for riparian sediments changed substantially and predictably with depth and time post dam removal/breach. We also found that physiochemical parameters evolved asynchronously at different rates. Redox sensitive N and Fe forms and physical ripeness changed rapidly within years and decades while TOC, TN, BD, and soil aggregation took a longer time. These assessments suggest that legacy sediments are maturing into soils at variable rates and these changes could extend from decades to centuries. A complex interaction of GW levels/drainage, sediment texture, and buried pre-dam soil horizons shaped this evolution. These results demonstrate that anthropogenic disturbance legacies can have a significant influence on soil pedogenesis, and these effects continue to persist for decades to centuries. Given the ubiquity of existing and removed dams and ongoing removals across the US and worldwide, hundreds to thousands of miles or kilometers of riparian zones and their sediment profiles are likely in the range of pedogenic evolutionary states described in this study. Understanding these pedogenic changes and the drivers involved is crucial for advancing our knowledge of soil evolution and for developing new paradigms that account for the role of human activities and legacies. Furthermore, riparian zones and their soils are also a cornerstone of contemporary watershed management practices, recognized for their ability for buffering upland nutrient pollution (particularly N) under natural conditions (Vidon et al., 2010). Our observations highlight that dams alter riparian sediment/soil N retention and long-term biogeochemical trajectories. Given that national soil survey maps rarely mention or characterize the effects of dams on riparian soils, identifying these changes are particularly important for assessing the buffering capacity (current and future) and pollution mitigation potential of riparian zones. Legacy effects of dams for riparian soils provide valuable information for floodplain restorations indicating which soil metrics are expected to recover early versus late and the rates of recovery post dam removals.
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Progress 07/01/23 to 06/30/24
Outputs
Target Audience:University researchers, faculty, students, and extension personnel. Federal, state, and local governments Nonprofit environmental organizations Changes/Problems:There are no major problems to report. The only change is that the Roller Mill dam that was slated to be removed in 2024 has been delayed to 2025. This has been because of some delays associated with funding for dam removal and time to address the concerns of residents near the dam. We expect the dam will be removed in 2025 and that will allow us to do the short-term high frequency sampling of the upstream riparian sediments post dam removal. What opportunities for training and professional development has the project provided?This project has provided important opportunities for training and development for multiple personnel - those funded directly on the project as well as those who are not supported by the project. Postdoc Dr. Eric Moore is leading the field sampling campaigns with the assistance of multiple other postdocs and graduate students from Inamdar's research group. These unfunded personnel include - Drs. Moklesur Rahman and Joe Galella and PhD students Matt Sena, Bisesh Joshi and Alexis Yaculak. The project is also supporting the professional development of the PIs (Inamdar, Peipoch and Kan) and two technicians - Laura Borecki and Stephanie Bernasconi. As a result of this study, PIs have also been able to develop new collaborations and partnerships with researchers and floodplain restoration practitioners in Pennsylvania, Delaware and Maryland. How have the results been disseminated to communities of interest?The first conference presentation from this project is planned for the 2024 AGU Meeting in Washington DC in December 2024. Dr. Eric Moore will make this presentation and we expect a manuscript from this work will be submitted in early spring 2025. Plans and sampling for this project have been shared with state and local environmental agencies in Pennsylvania, Delaware and Maryland and they are very interested in the results from this study. This study has major implications for relict dam removal projects in these states. What do you plan to do during the next reporting period to accomplish the goals?We expect 1-2 manuscripts will be submitted during the next report period addressing Objectives 1, 3, and 4. These manuscripts will discuss the long term physical, chemical, and microbial changes in riparian sediments post dam removals and evaluate how these changes align with soil development models post drainage. Sampling to address Objective 2 will be initiated following the removal of the Roller Mill dam on Chiques Creek in Pennsylvania. This sampling will provide important short-term changes in soil physiochemical properties post dam removal. We expect multiple conference presentations on these two issues during the next reporting period.
Impacts
What was accomplished under these goals?
Extensive sampling was performed this year to address objectives O1 and O3. This sampling exceeds the scope that we had proposed (details below). Riparian sediment sampling was performed across four watersheds with existing and removed milldams. These watersheds include - Chiques Creek (originally proposed) in Pennsylvania, Big Elk Creek in Maryland, Christina River in Delaware, and White Clay Creek in Delaware. 13 distinct riparian soil cores have been collected to date from the four drainage systems as listed below. Chiques Creek Watershed: - name of dam, existing or breached/removed dam and date of removal, number of depths sampled and max depth Heistand dam, breached, 2015, 7 samples, 84 inches Shenck dam, breached, 1954, 5 samples, 60 inches Johnston dam, breached, 1926, 4 samples, 48 inches Krady dam, breached, 2018, 9 samples, 108 inches White Oak dam, breached, 1972, 7 samples, 84 inches Siegrist dam, existing since mid 1700s, 9 samples, 108 inches Roller mill dam, existing since mid 1700s, 11 samples, 120 inches Big Elk Creek Watershed: Scotts dam, breached, 1935, 13 samples, 156 inches Parks dam, breached, 1935, 13 samples, 156 inches Spring lawn dam, breached, 11 samples 132 inches Christina River Watershed Cooch dam, existing since 1792, 11 samples, 132 inches Old Cooch dam, breached, ~ date unknown, 7 samples, 72 inches White Clay Creek Watershed Woolen mill dam, existing since mid 1700s, 8 samples, 96 inches All sediment samples are currently being analyzed for - Texture (% sand, silt and clay) Aggregation (macro and micro aggregates) Bulk density Soil moisture Soil pH Electric conductivity %OM Nitrate-N Ammonium-N Total N and total C Mehlich3 extractable elements Crystalline and amorphous fractions of sediment Fe through extractions PLFA metrics on microbes Denitrification enzyme assays Functional genes for nitrogen Currently samples are being analyzed and data is coming in. RESULTS TO DATE: Preliminary results indicate important differences between riparian sediments with and without (breached/removed) dams. Sediment ammonium-N and Fe concentrations are elevated and increase with sediment depth for sites where dams still exist. These elevated concentrations are attributed to the saturated and reducing conditions in the sediments upstream of the existing dams. In contrast, sediment-bound nitrate-N concentrations are very low for the same reducing sediments. This is likely because of denitrification losses of nitrate-N. In contrast to existing dams, sediment ammonium-N concentrations at sites where dams have been long breached are very low or non-detectable. This suggests that ammonium-N in sediments declines following dam removal due to nitrification and subsequent loss of nitrate-N via drainage or denitrification. The sediments also reveal distinct patterns in texture (% sand, silt and clay) with sediment depths and across drainage watersheds. Chiques Creek watershed located in Pennsylvania has the lowest sand contents and the highest silt and clay percentages. The silt and clay in Chiques sites are generally elevated for the full legacy sediment profile upstream of the dams. In contrast to Chiques, the Big Elk Creek, Christina, and White Clay Creek watersheds show higher sand contents. This is not surprising given that these three watersheds are at the transition region from Piedmont to the Coastal plain physiographic region. The vertical changes texture are especially pronounced for the Big Elk Creek, Christina, and White Clay Creek riparian sites. Precolonial floodplains (located below the legacy sediments are coarse and have buried organic horizons that are indicated by elevated sand and organic carbon contents. Above the precolonial sediments, fine grained sediment sediments are the highest (highest % silt and clay). These sediments were trapped when the dams were constructed and had the highest sediment trapping efficiency. The % sand content then progressively increases towards the surface as the ponds upstream of the dams are filled up and the sediment trapping efficiency declines. The coarsest fractions are typically at the surface layer. The organic carbon contents are elevated in the precolonial sediments and closer to the riparian surface where a O horizon is stating to develop. Thus, vertical profiles of texture and organic carbon provide important insights into how precolonial and post-colonial sediments deposited and changed over time. Initial data also suggests that microbial and bacterial biomass declines with depth and is highest at the terrace surface. For the same surficial depths, microbial biomass appears to be greater at sites where the dams have been breached or removed versus sites with existing dams. We expect additional novel trends as we analyze and process the data that is coming in. Initial assessments suggest that sediment are maturing into soils at extremely slow rates that could extend from decades to centuries. Removal of the Roller mill dam in Pennsylvania has been delayed and is now expected to occur in the summer of 2025. Sampling of sediments post removal of this dam will allow us to address Objective 2.
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