Status: 

Completed

Title

Rio Icacos hyporheic and riparian chemistry
Summary

Short name: 

LUQMetadata109

Data set ID: 

109

Abstract: 

Hydrologic and chemical characteristics were determined for both riparian and hyporheic subsurface flow along a 100-m reach of a sandy-bottom tributary of the Rio Icacos in the Luquillo Experimental Forest, Puerto Rico. Hydrologic data (vertical hydraulic gradient and hydraulic conductivity of streambed sediments) and the topographic and morphological features of the watershed indicated diffuse inputs of groundwater from the near-stream riparian zone along this site. Cumulative groundwater discharge, determined by tracer dilution techniques, was ~1.5 L/s or 10% of the total stream discharge. Spatial heterogeneity in hydrologic and chemical properties of riparian and hyporheic sediments was large. Hydraulic conductivity explained much of the variation in NH4-N and dissolved organic carbon (DOC) concentrations, with highest concentrations in sites having low conductivity. A mass-balance approach was used to examine the influence of the near-stream zone on nutrient transport and retention. Outwelling riparian groundwater had the potential to increase stream N concentrations by up to 84% and DOC concentrations by up to 38% along our 100-m reach. Because stream concentrations were constant downstream despite this input, we conclude that significant N and C retention or loss were occurring in the near-stream zone. Lotic ecosystems and their associated riparian groundwater can have a quantitatively significant impact on the nutrient budgets of tropical headwater catchments.

Dates
Date Range: 
2003-01-28 00:00:00 to 2007-11-28 00:00:00

Publication Date: 

2011-06-07 00:00:00
People

Additional Project roles: 

Name: Eda Melendez-Colom Role: Data Manager
Name: Tamara Chestnut Role: Associated Researcher
Methodology

Methods: 

Soil solution was collected approximately every month from the zero tension lysimeters within the CTE plots. Samples were filtered through a pre-combusted GF/F filter, frozen and shipped to the Water Quality Analysis Lab for analysis at the University of New Hampshire, Durham, NH.

Instrumentation: 

Cl - liquid chromatography with conductivity detection

NO3-N - liquid chromatography with conductivity detection

SO4-S - liquid chromatography with conductivity detection

Na, K, Mg, and Ca - liquid chromatography with conductivity detection

NH4-N - automated colorimetric analysis (phenolhypochlorite)

PO4-P - automated colorimetric analysis (molybdate blue)

DOC - high temperature catalytic oxidation

TDN - high temperature catalytic oxidation with chemiluminescent detection

SiO2 - automated colorimetric analysis (molybdate blue)

DON - by difference (TDN - NO3-N - NH4-N)

Status: 

Completed

Time Period: 

Short-Term