More Like this

1. A multi-tracer model approach to estimate reef water residence times: A multi-tracer residence time model

   https://doi.org/10.4319/lom.2012.10.1078  

   Venti, A.; Kadko, D.; Andersson, A. J.; Langdon, C.; Bates, N. R. (December 2012, Limnology and Oceanography: Methods)
2. Estuarine Circulation, Mixing, and Residence Times in the Salish Sea

   https://doi.org/10.1029/2020JC016738  

   MacCready, P.; McCabe, R. M.; Siedlecki, S. A.; Lorenz, M.; Giddings, S. N.; Bos, J.; Albertson, S.; Banas, N. S.; Garnier, S. (February 2021, Journal of Geophysical Research: Oceans)

   Abstract A realistic numerical model is used to study the circulation and mixing of the Salish Sea, a large, complex estuarine system on the United States and Canadian west coast. The Salish Sea is biologically productive and supports many important fisheries but is threatened by recurrent hypoxia and ocean acidification, so a clear understanding of its circulation patterns and residence times is of value. The estuarine exchange flow is quantified at 39 sections over 3 years (2017–2019) using the Total Exchange Flow method. Vertical mixing in the 37 segments between sections is quantified as opposing vertical transports: the efflux and reflux. Efflux refers to the rate at which deep, landward‐flowing water is mixed up to become part of the shallow, seaward‐flowing layer. Similarly, reflux refers to the rate at which upper layer water is mixed down to form part of the landward inflow. These horizontal and vertical transports are used to create a box model to explore residence times in a number of different sub‐volumes, seasons, and years. Residence times from the box model are generally found to be longer than those based on simpler calculations of flushing time. The longer residence times are partly due to reflux, and partly due to incomplete tracer homogenization in sub‐volumes. The methods presented here are broadly applicable to other estuaries. 

   more » « less
3. Isotopic Heterogeneity of Stem Water in Conifers Is Correlated to Xylem Hydraulic Traits and Supports Multiple Residence Times

   https://doi.org/https://doi.org/10.3389/frwa.2022.861590  

   William Bowers and David Williams (January 2022, Frontiers in water)
4. Shelf‐Basin Interactions and Water Mass Residence Times in the Western Arctic Ocean: Insights Provided by Radium Isotopes

   https://doi.org/10.1029/2019JC014988  

   Kipp, Lauren E.; Kadko, David C.; Pickart, Robert S.; Henderson, Paul B.; Moore, Willard S.; Charette, Matthew A. (May 2019, Journal of Geophysical Research: Oceans)

   Abstract Radium isotopes are produced through the decay of thorium in sediments and are soluble in seawater; thus, they are useful for tracing ocean boundary‐derived inputs to the ocean. Here we apply radium isotopes to study continental inputs and water residence times in the Arctic Ocean, where land‐ocean interactions are currently changing in response to rising air and sea temperatures. We present the distributions of radium isotopes measured on the 2015 U.S. GEOTRACES transect in the Western Arctic Ocean and combine this data set with historical radium observations in the Chukchi Sea and Canada Basin. The highest activities of radium‐228 were observed in the Transpolar Drift and the Chukchi shelfbreak jet, signaling that these currents are heavily influenced by interactions with shelf sediments. The ventilation of the halocline with respect to inputs from the Chukchi shelf occurs on time scales of ≤19–23 years. Intermediate water ventilation time scales for the Makarov and Canada Basins were determined to be ~20 and >30 years, respectively, while deep water residence times in these basins were on the order of centuries. The radium distributions and residence times described in this study serve as a baseline for future studies investigating the impacts of climate change on the Arctic Ocean. 

   more » « less
5. Effects of Successive Peak Flow Events on Hyporheic Exchange and Residence Times

   https://doi.org/10.1029/2020WR027113  

   Singh, Tanu; Gomez‐Velez, Jesus_D; Wu, Liwen; Wörman, Anders; Hannah, David_M; Krause, Stefan (July 2020, Water Resources Research)

   Abstract Hyporheic exchange is a crucial control of the type and rates of streambed biogeochemical processes, including metabolism, respiration, nutrient turnover, and the transformation of pollutants. Previous work has shown that increasing discharge during an individual peak flow event strengthens biogeochemical turnover by enhancing the exchange of water and dissolved solutes. However, due to the nonsteady nature of the exchange process, successive peak flow events do not exhibit proportional variations in residence time and turnover, and in some cases, can reduce the hyporheic zones' biogeochemical potential. Here, we used a process‐based model to explore the role of successive peak flow events on the flow and transport characteristics of bedform‐induced hyporheic exchange. We conducted a systematic analysis of the impacts of the events' magnitude, duration, and time between peaks in the hyporheic zone's fluxes, penetration, and residence times. The relative contribution of each event to the transport of solutes across the sediment‐water interface was inferred from transport simulations of a conservative solute. In addition to temporal variations in the hyporheic flow field, our results demonstrate that the separation between two events determines the temporal evolution of residence time and that event time lags longer than the memory of the system result in successive events that can be treated independently. This study highlights the importance of discharge variability in the dynamics of hyporheic exchange and its potential implications for biogeochemical transformations and fate of contaminants along river corridors. 

   more » « less