An official website of the United States government
This is the AmeriFlux version of the carbon flux data for the site US-Skr Shark River Slough (Tower SRS-6) Everglades. Site Description - The Florida Everglades Shark River Slough Mangrove Forest site is located along the Shark River in the western region of Everglades National Park. Also referred to as site SRS6 of the Florida Coastal Everglades LTER program, freshwater in the mangrove riverine floods the forest floor under a meter of water twice per day. Transgressive discharge of freshwater from the Shark river follows annual rainfall distributions between the wet and dry seasons. Hurricane Wilma struck the site in October of 2005 causing significant damage. The tower was offline until the following October in order to continue temporally consistent measurements. In post-hurricane conditions, ecosystem respiration rates and solar irradiance transfer increased. 2007- 2008 measurements indicate that these factors led to an decline in both annual -NEE and daily NEE from pre-hurricane conditions in 2004-2005.
more »
« less
Comparative Use of Hydrologic Indicators to Determine the Effects of Flow Regimes on Water Quality in Three Channels across Southern Florida, USA
This study determines the relationships between water flow and water quality in three types of channels in southern Florida, USA: Shark River Slough, Peace River, and Hillsboro Canal. Peace River most resembles a natural channel with floodplain connectivity, sinuosity, and uninhibited flow. Shark River Slough has a natural, shallow channel with sheet flow, while the Hillsboro Canal is the most modified channel due to dredging, straightening, and regulated flow. Hydrologic indices for each channel were estimated to characterize flow regimes and flow variability, while concentration–discharge (C–Q) relationships were determined to quantify the impact of flow regime on water quality. The greatest variability in flow occurred at the Hillsboro Canal, followed by Peace River and Shark River Slough. Connectivity to floodplains and long durations of low and high flow pulses at Peace River and Shark River Slough contributed to the dilution of water quality constituent concentrations at higher flows. Conversely, the channelized characteristics of the Hillsboro Canal resulted in an enrichment of constituents, especially during high flows. This study suggests that C–Q relationships can be used in canal discharge management to prevent water quality degradation of sensitive downstream wetland and aquatic ecosystems.
more »
« less
- Award ID(s):
- 2025954
- PAR ID:
- 10287064
- Date Published:
- Journal Name:
- Water
- Volume:
- 13
- Issue:
- 16
- ISSN:
- 2073-4441
- Page Range / eLocation ID:
- 2184
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
How does the physical and chemical structure of the Critical Zone (CZ), defined as the zone from treetops to the bottom of groundwater, govern its hydro-biogeochemical functioning? Multiple lines of evidence from past and newly emerging research have prompted the shallow and deep partitioning concentration-discharge (C-Q) hypothesis. The hypothesis states that in-stream C-Q relationships are shaped by distinct source waters from flow paths at different depths. Base flows are often dominated by deep groundwater and mostly reflect groundwater chemistry, whereas high flows are often dominated by shallow soil water and thus mostly reflect soil water chemistry. The contrasts between shallow soil water versus deeper groundwater chemistry shape stream solute export patterns. In this context, the vertical connectivity that regulates the shallow and deep flow partitioning is essential in determining chemical contrasts, biogeochemical reaction rates in soils and parent rocks, and ultimately solute export patterns. This talk will highlight insights gleaned from multiple lines of recent studies that include collation of water chemistry data from soils, rocks, and streams in intensively monitored watersheds, meta-analysis of stream chemistry data at the continental scale, and integrated reactive transport modeling at the hillslope and watershed scales. The hypothesis underscores the importance of subsurface vertical structure and connectivity relative to the extensively studied horizontal connectivity. It also alludes to the potential of using streams as mirrors for subsurface water chemistry, and the potential of using C-Q relationships to infer flow paths and biogeochemical reaction rates and the response of earth’s subsurface to climate and human perturbations. Broadly, this simple conceptual framework links CZ subsurface structure to its functioning under diverse climate, geology, and land cover conditions.more » « less
-
null (Ed.)Northeast Shark River Slough (NESS), lying at the northeastern perimeter of Everglades National Park (ENP), Florida, USA, has been subjected to years of hydrologic modifications. Construction of the Tamiami Trail (US 41) in 1928 connected the east and west coasts of SE Florida and essentially created a hydrological barrier to southern sheet flow into ENP. Recently, a series of bridges were constructed to elevate a portion of Tamiami Trail, allow more water to flow under the bridges, and attempt to restore the ecological balance in the NESS and ENP. This project was conducted to determine aspects of soil physiochemistry and microbial dynamics in the NESS. We evaluated microbial respiration and enzyme assays as indicators of nutrient dynamics in NESS soils. Soil cores were collected from sites at certain distances from the inflow (near canal, NC (0–150 m); midway, M (150–600 m); and far from canal, FC (600–1200 m)). Soil slurries were incubated and assayed for CO2 emission and β-glucoside (MUFC) or phosphatase (MUFP) activity in concert with physicochemical analysis. Significantly higher TP contents at NC (2.45 times) and M (1.52 times) sites than FC sites indicated an uneven P distribution downstream from the source canal. The highest soil organic matter content (84%) contents were observed at M sites, which was due to higher vegetation biomass observed at those sites. Consequently, CO2 efflux was greater at M sites (average 2.72 µmoles g dw−1 h−1) than the other two sites. We also found that amendments of glucose increased CO2 efflux from all soils, whereas the addition of phosphorus did not. The results indicate that microbial respiration downstream of inflows in the NESS is not limited by P, but more so by the availability of labile C.more » « less
-
Abstract Intermittent streams that regularly dry up constitute over half of the world's river network. They exhibit biogeochemical processes distinct from those of continuously flowing perennial rivers. In perennial rivers, discharge is often perceived as predominantly driving water chemistry, as demonstrated by the widespread use of concentration–discharge (CQ) relationships. Does discharge similarly drive water chemistry in intermittent streams? Given its extended periods of no flow, we hypothesized that stream chemistry depends less on discharge alone but more on the granularity of dry‐wet transitions, including their direction (drying or rewetting), history (antecedent conditions), and intermittency. We tested this hypothesis by analyzing three decades of streamflow and solute chemistry data from an intermittent stream (N04D) in the Konza Prairie Biological Station, a Long‐Term Ecological Research site in Kansas, USA. Results showed that concentrations are generally higher at no flow compared to flow conditions and depend on dry‐wet transitions. Geogenic solutes were predominantly chemostatic (relatively constantCwithoutQdependence), contrasting primarily dilution patterns (decreasingCwithQ) in perennial rivers. Biogenic solutes did not exhibit pronounced discharge‐dependent patterns commonly observed in perennial rivers at decadal scale; at monthly scale, however, they exhibited a transition from highly variableCQpatterns at low flows to consistent flushing patterns (increasingCwithQ) at flows higher than 2.5–5 mm/day. These observations support our hypothesis of weaker chemistry dependence on discharge in intermittent streams. We further hypothesize that the emerging discharge thresholds signal a tipping point at which intermittent streams switch from a dry state governed by intermittency‐driven biogeochemistry to a wet, discharge‐driven state resembling perennial rivers. The hypothesis calls for intensive data collection at dry‐wet transitions to develop theories and models for intermittent streams that have become increasingly prevalent globally.more » « less
-
Abstract Water‐mediated linkages that connect landscape components are collectively referred to as hydrologic connectivity. In river‐floodplain systems, quantifying hydrologic connectivity is challenging yet enables descriptions of hydrologic function that emerge from complex, heterogeneous interactions of underlying geomorphic, climatic and biologic controls. Here, we quantify surface water hydrologic connectivity using field indicators and develop a connectivity strength metric across a river‐floodplain system. To measure connectivity strength, we analyzed hydrometric data, conservative tracers, and natural occurring geochemical and microbial tracers across streamflows. We developed empirical models of hydrologic connectivity and predicted daily connectivity strength values across sites and assessed the sensitivity of connectivity to streamflow variability. Some floodplain areas were consistently connected or disconnected to the river, while other floodplain areas exhibited variable connectivity strength through the season. Of the locations with intermittent connectivity, some disconnected quickly and others had a prolonged disconnection phase. At the river‐floodplain system scale, we found hydrologic connectivity always increased with streamflow while across‐system variance in connectivity peaked at intermediate streamflow. Floodplain locations with intermittent surface connectivity demonstrated inter‐annual variability in hydrologic connectivity as a function of climate variability. Our results suggest that intermediate flows are critical periods for seasonal connectivity regimes and understanding the influence of changing climate on full flow durations will be required to predict impacts on river‐floodplain connectivity.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.3390/w13162184
