The Green Valley through Patrick's Eyes, Guest Posting by Patrick Options

[John_Sode]

7/28/05

Hydrology field work in the Green Valley near Thule, NW Greenland, July 19th, 2005

The morning after we arrived at our Green Valley base camp, our group was shuttled by helicopter to the headwaters of the Green Valley drainage. We split into four groups working on soils, vegetation, hydrology, or GPS surveys. The first three groups moved down valley, periodically stopping to take measurements and samples, and the GPS crew hiked to a drop point for their equipment to begin the installation of monuments (large bolts) in rocks to measure the creep of solfluction lobes (down slope soil movement).
In our hydrology crew, we were focused on measuring pH, electrical conductivity (ion content), and temperature of the water, as well as taking samples for water chemistry analysis (such as carbonate and trace elements), and samples to specifically analyze nitrogen isotopes (N-15). We were particularly interested in the effect of the large dovekey populations in the valley and how this nitrogen-input changes downstream.
The story of the Green Valley is of a micro-ecosystem operating within a single valley where geology, chemistry, and biology all interact to create an extremely rich and fertile valley in a generally dry and barren region. The rocks here are beautifully banded and folded crystalline metamorphic rocks – gneiss mostly – unlike the dominantly carbonate lithology of the Thule region. This creates for slopes that erode to large blocky talus, rather than fine-grained sands and pebbles, which creates excellent nesting habitat for the dovekeys who need protection from foxes and raptors.
The dovekeys are the nutrient movers. They eat krill and other marine species from the coastal areas and then fly up valley, depositing their nitrogen-rich feces around the talus slopes. These nutrients move into the waters and are transported down valley. The result is a rich community of naturally fertilized arctic vegetation. This, in turn, provides a food source for the muskox populations in the valley.
So our group moved down valley from the helicopter drop off point in snowfields at the headwater divide, assessing the role that water plays in this nutrient cycle. We found that waters were more acidic near the talus slopes where the dovekeys nested (pH near 4.0), especially in springs emerging directly beneath the slopes, giving evidence for a higher nitrogen content at these locations. N-15 analysis will also be done on krill that the dovekeys are eating, to make sure that this is the nitrogen source.
In addition to water chemistry, we also measured discharge levels throughout the valley. One person wades out across a tape-measure line set perpendicular to current flow, measuring water depth and velocity approximately every 40 cm. A value for flow can then be calculated. These measurements are the real ‘fieldwork’ component of the hydro project….wading hip deep across a fast moving arctic stream that is only slightly above freezing.
This work will produce valuable results on nutrient cycling in the Green Valley, as well as a full water chemistry analysis, identification of the source waters (i.e. snowmelt vs. rainwater), and the change in flow levels from the drainage divide to the ocean. Look for published papers on this work in the coming year or so.
A beautiful raging arctic storm with 60 MPH wind gusts kept us tent bound the entire next day. We watched waves slamming against icebergs and headlands, while groups of dovekeys numbering in the hundreds and thousands still dove and twisted in their flocking patterns despite the extreme winds.
Our entire group offers great thanks to Birgit Hagedorn for leading the hydrology groups, and to Erin Whorton for assistance in the lab and field. Birgit and Erin are spending the entire summer season observing stream flow around Thule, and we are very privileged to learn from their experience and knowledge.

--Patrick Wright
High Arctic Field Camp, 2005.