Observatory infrastructure and sampling design

The LCZO infrastructure, sampling strategy, and integrated data management system are designed to provide a platform whereby collaborators can put geochemical and biogeochemical studies into a geomorphic and hydrologic perspective. The basic infrastructure of the LCZO is an integrated set of sampling sites (e.g. nodes in Table 2) that are built upon existing study sites that have long-term and ongoing records of rainfall, throughfall, litterfall, and streamflow (Schellekens et al 2004, Peters et al 2006, Heartsill et al 2007, Wei et al 2007). The atmospheric sampling nodes consist of 8 weather stations and an additional 8 rain gages that monitor climatic and geochemical inputs to the different lithologies and forest types across a precipitation gradient that ranges from 1000 mm/yr to 5000 mm/yr. Soil and deep weathering nodes consist of a sampled network of soils on the various lithologies and forest types and monitored hillslope catena’s that are underlain by VC and GD lithologies (Table 2). Soil and regolith water and gas samples are sampled using suction samplers installed according to our previous studies and CZEN standards. Aquatic nodes of the observatory focus on quantifying the fluxes of water, sediment, and solutes from the basin and how they are transformed as they move from pore spaces in the lithologic matrix to the coastal zone. These nodes include 8 stream gages and numerous georeferenced cross-sections and riparian sampling sites. A major limitation to previous studies has been the ability to monitor storm events and temporal variations in exports. To overcome this limitation, the LCZO is adding sensors to the existing stream gages to obtain continuous records of conductivity, and temperature.

Water chemistry is sampled weekly and on a campaign basis and will be processed at the USGS WEBB laboratories and at the University of New Hampshire. While the water chemistry at most of the proposed aquatic sampling nodes has been sampled before, sampling frequency has been erratic and the actual data is stored in different ways and at different institutions. The LCZO is ameliorating this situation by developing a centralized data management archive where researchers can access existing data and share the new data they collect.

Contact Information:

Luquillo-CZO@sas.upenn.edu
Luquillo Critical Zone Observatory
Department of Earth and Environmental Science
University of Pennsylvania
http://www.sas.upenn.edu/lczo

Table 2. Planned location of infrastructure and measurements proposed for the Luquillo Critical Zone Observatory. Ex = existing, no upgrade required, Ux = upgrade of existing infrastructure required, Nx = new installations, x = year of planned upgrade or installation.

Sampling Node (Principal)	Infrastructure and Measurements	Volcaniclastic (Bisley/Mameyes)	Granodiorite (Guaba/Icacos/Rio Blanco)
Soil and Deep Weathering Nodes
Deep Weathering (Brantley)	Surface to bedrock lysimeters, tensiometers, & gas samplers.  Periodic & event sampling, XRF, mineralogy, archived soils	Bisley Ridge (N1) Bisley Slope (N2) Bisley Riparian (N3)	Guaba Ridge (U1) Guaba Slope (U2) Icacos Riparian (N2)
Redox (Silver)	Surface to bedrock Apogee oxygen sensors, trace gas, H20 content, samplers,	Bisley Ridge (N1) Bisley Slope (N2) Bisley Riparian (N3)	Guaba Ridge (U1) Guaba Slope (U1) Icacos Riparian (N2)
Soil (Johnson)	Quantitative pits & bore holes, SOM, total and extractable nutrients, X-ray, grainsize, hydrologic properties	Multiple quantitative soil pits at the intensive research sites and throughout the Luquillo Mountains, stratified by climate, bedrock, and land cover (N1-5)
Aquatic Sampling Nodes
Fluvial (Jerlomack, Scatena McDowell Shanley)	Upgrade gages with permanent cross-sections (U1,2), bedload transport estimates (U1-3), Be10 denudation rates (N2-5) expand water sampling (U1), sensors for conductivity & temp (N1,2)	USGS 655 (U1) Bisley Q1-3 (U2) USGS 660 (E) USGS 670 (E)	Icacos USGS 750 (U1) Guaba USGS 749 (U2) Rio Blanco USGS (E)
Riparian (McDowell)	Piezometers, tensiometers, lysimeters & gas samplers, Periodic & event sampling	Bisley (U1,2) Multiple sites along R. Mameyes	Icacos (U1,2) Multiple sites along R. Blanco
Coastal (Horton)	Short cores and surface samples	Mameyes estuary and coastal zone	Rio Blanco estuary and coastal zone
Atmospheric Sampling Nodes
Atmospheric Climate Stations (E) (Shanley, Scholl, UPR)	Hourly & daily climate (precip, temp., radiation, RH, wind, soil moisture etc,) Periodic & event sampling of chemistry, stable isotopes	Upgrade and standardize existing network supported by USGS WEBB, USFS IITF, and UCB at Icacos, Bisley and Sabana. Isotope samplers will be established as needed. 8 stations and 8 rain gages will be operational
Data Management (Scatena)	Web site at UPENN (http://www.sas.upenn.edu/lczo/) will provide the portal to all LCZO activities.  Data will be managed by an integrated data management system that is linked to National CZO portal.

 

Literature Cited

Heartsill-Scalley T., Scatena F.N., Estrada C., McDowell W.H., Lugo A.E., 2007. Disturbance and long-term patterns of rainfall and throughfall nutrient fluxes in a subtropical forest in Puerto Rico.  Journal of Hydrology, 33:472-485

Peters N.E., Shanley J.B., Aulenback B.T., Webb R.M., Campbell, Huny R., Larsen M.C., Stallard R.F., Troester J., Walker J.F. 2006.  Water and solute mass balances of five relatively undisturbed watersheds in the U.S. Science of the Total Environment 358:221-242

Scatena F.N., Blanco J.B., Beard K., Waide R., Lugo A.E., Brokaw N., Silver W., Haines B., Zimmerman J., in press.  The Luquillo Disturbance Regime.  Chapter 4 in A Caribbean Forest Tapestry: A Multidimensional Nature of Disturbance and Response. Luquillo LTER Synthesis Book, Cambridge University Press

Scholl, M.A., Shanley J.B., in press, A new explanation for the stable isotope amount effect using NEXRAD echo tops: Luquillo Mountains, Puerto Rico. Water Resources Research

Schellekens J., Scatena F.N., Bruijnzeel L.A., van Dijk A.I. J.M., Groen M.M.A., van Hoogezand R.J.P., 2004.  Stormflow generation in a small rain-forest catchment in the Luquillo Experimental Forest, Puerto Rico.  Hydrological Processes 18. 505-530

Shanley J.B., Mast M.A., Campbell D., Aiken G.R., et al. 2008 Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach. Environmental Pollution 154: 1-12

Wei Wu, Hall C.A.S., Scatena F.N., 2007 Modeling the impact of land use change on the stream flows at the meso-scale watershed level in North-Eastern Puerto Rico.  Hydrological Processes V21 DOI: 10.1002/hyp.6515