nitrate

Nutrient tracer injection experiments in supraglacial streams on Canada Glacier, Antarctica, January 2019

Abstract: 

This dataset contains a series of grab samples collected from nutrient tracer injection experiments conducted in supraglacial streams on Canada Glacier in Taylor Valley, Antarctica. The purpose of these experiments was to measure potential nutrient uptake in supraglacial stream networks. We chose three reaches and co-injected nutrient tracer(s) and a conservative tracer (NaCl). Tracers were injected at the top of each reach, allowed to mix with the stream water, and move downstream. Grab samples in this dataset were collected at the base of the reach over the course of these tracer experiments, which ran from 14-19 January 2019.

Core Areas: 

Associated Personnel: 

1021
1025
1022
1023

Dataset ID: 

2017

Short name: 

GLACIER_SUPRA_TRACER

Data sources: 

GLACIER_SUPRA_TRACER

Methods: 

We performed a series of nutrient tracer experiments in each of the three study reaches over the week of 14-19 January 2019, starting farthest downstream at Reach 2. Three stream reaches were located in the lower Canada Glacier ablation zone of Taylor Valley, Antarctica (Reach 1: -77.62767, 163.96059; Reach 2: -77.6281, 163.957583; Reach 3: -77.629258, 163.964103). Prior to each addition, we collected at least two background samples from both the bottom and top of the study reach. For each experiment, we released known masses of nutrients (N as NaNO3, P as KH2PO43-, and C as glucose) and conservative tracer (NaCl) pre-dissolved in 1 L of stream water as an instantaneous slug at the head of the reach. At the base of the reach, we took grab samples at regular intervals of salt concentration change as measured by a handheld electrical conductivity probe. We analyzed grab samples for NO3-, PO43-, and major ions using an IC located at McMurdo Station. We released only one tracer per day in any given reach to assure all concentrations were fully at background levels before the next tracer experiment. We did a series of tracer injections combining different nutrients: N as NaNO3, N+P (NaNO3 and KH2PO43-), N+P+C (NaNO3, KH2PO43-, and glucose). We had deteriorating weather over the course of the six days in which we conducted tracer experiments. A 24 hour period of clouds and low temperatures caused the smaller upper reaches to freeze such that we were not able to conduct the N+P+C tracer on reaches 1 and 3. We instead moved back down to reach 2, which had low, but adequate, discharge to conduct an N+C tracer experiment. Data were analyzed using methods outlined in Covino et al., 2010 to calculate N and P uptake rates. 

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