Measuring Mass Fluxes of Nutrients to a First Order Stream within a Pristine Mountain Rainforest in Costa Rica

1Lia V. Gomez, 2William Ngyuen, 3Peter Knappett, 4Kelly Brumbelow, 5Gretchen Miller, 6Georgianne Moore, 7Abigail Keebler, 8Beth Prior, 9Alexander Duffy

1Iowa State University Dept. of Agriculture and Life Sciences; 2University of Maryland, College Park; 3Department of Geology & Geophysics, 4Texas A&M University; Texas A&M Univeristy; 5Zachry Dept. of Civil Engineering, 6Dept. of Ecosystem Science and Management, 7Westchester University, 8Auburn University, 9Texas A&M University

Funding for this Research Experiences for Undergraduate program is provided by the National Science Foundation’s Division of Earth Sciences (EAR-1659848).

Introduction

Differentiation: A double analysis

Costa Rica’s montane rainforests form an integral part of the economic, social, and environmental well-being of the country. They supply water for agriculture, hydroelectric power, and human consumption. Release of nutrients to streams from rainforests is poorly studied. This information will inform an ongoing public debate over the importance of restoring rainforests in areas formerly cleared for farming. The primary objective in this study was to measure the mass fluxes of nutrients to a first-order mountain stream within a pristine rainforest.

• The overarching goal was to assess the Peñas Blancas stream from various facets to:• Characterize streamflow and water table

responses to rainfall events as a function of watershed size

• Determine mass nutrient fluxes• This study was divided into two parts:

• a high frequency sampling period used for Isotope assessment

• Medium frequency sampling period that • The Pristine rainforest of Costa Rica are

underassessed; the above lens way to obtain a general notion towards the hydrology of the Peñas Blancas Watershed.

Objectives

• The sampling site is within the Texas A&M Soltis Center in Alajuela State, Costa Rica.

• A total length of the stream reach is 180 meters in length

• The stream assessed spans a 75m reach• The stream flows through an elevation

gradient of 68.6m

Site Description

• Determine total mass nutrient fluxes via End Member Mixing Analysis (EMMA), in a pristine rainforest catchment in the Alajuela State, Costa Rica

• Depict overall mass fluxes in a hydrograph model to illustrate their variance alongside precipitation levels

• Assess the feasibility of implementing EMMA in a pristine rainforest with a tremendous amount of biodiversity and numerous variables

Methodology

• A 75m reach of a first-order stream in the PeñasBlancas River watershed (Howler Monkey Stream) was intensively studied.

• Synoptic sampling every 2 hours was performed on the upstream and downstream ends of this reach for 48 hours

• Soil water and shallow groundwater was sampled from 4 piezometers and 2 seeps

• Analyses measured in the field included: (list all) which were measured in the field using a multi-meter and a hand-held spectrophotemeter

• In the laboratory at TAMU, (list all major ions) which were analyzed in the laboratory using an Ion Chromatograph.

Results and Discussion

Economic

Social

Environmental

Acknowledgements

Conclusion and Further Applications

Figure 1 Student researchers conduct a water quality analysis for labile parameters at the Peñas Blancas (upper) River transect.

Figure 2 Topographic map of the PeñasBlancas River sampling locations (Spacing=1m, Method = natural, Cont. Interval = 10 m (z)

Figure 3 Student Researchers assessing removing fallen tree debris from the Peñas Blancas River, lower gauge sampling point

Figure 4 Texas A&M University Soltis Center, Alajuela State, Costa Rica

Figure 6 Student Researchers assessing removing fallen tree debris from the Peñas Blancas River, lower gauge sampling point

Analyze Hypothesis

End Member Mixing Model

Isotope Assessment

High frequency rainwater sampling

Daily sampling

48 hour data

analysis

Gain a snapshot of

the watersheds

interworking's

Examine

Figure 5 A qualitative representation for the schematics and objective of the Watershed studied.

Figure 6 Student Researchers auguring a well into the left bank of the Peñas Blancas left bank

Figure 7 Student Researchers developing wells for piezometer installation.

Figure 8 Upstream view of the Peñas Blancas downstream weir/gauging site.

Figure 9 Student researcher preforming Nitrate analysis on the Peñas Blancas, upstream sampling location

Figure 10 Downstream view of Peñas Blancasupstream guage/temporary weir.

• The anticipated outcome is a separated hydrograph showing volumetric and mass fluxes from each of the source waters over the 48 hour period.

• Twelve major ions were analyzed with an ion chromatograph. Using End-member Mixing Analysis (EMMA) 7 source waters with unique chemistry supplied water to the stream along the study reach: 1) rain water; 2) fresh groundwater; 3) medium total dissolved solids (TDS) groundwater; 4) high TDS groundwater; 5) right bank seep; 6) left bank seep; and finally 7) upstream

• Further End member mixing analysis will be conducted to determine the variability and feasibility for implementing EMMA along pristine rainforest catchments

• A piper plot will be formulated to better assess correlations between cations and anions

• Nutrient concentrations from nitrates and nitrites will plotted against rainfall data to evaluate potential correlations

Figure 11 Preliminary, 11 parameter Principal Component Analysis

Figure 12 Preliminary, 9 parameter Principal Component Analysis

Figure 12 Bivariate End Member Mixing Analysis plotted against concentrations and potential end members for Peñas Blancas River watershed