The last hurrah

All of our sampling finally behind us, our expedition draws to a close. Yesterday was in some ways the simplest day, and in others the most ambitious. Most importantly, as you can see from the first photo, the skies graced us with an entire day of beautiful sunshine. Had it been pouring down rain, like the previous three days, our afternoon on the harbor patrol boat would have been less idyllic. But by some meteorological marvel, we were treated to lovely views of Vancouver and the surrounding Coast Range as we steamed around the Fraser delta.

Our sole objective at this station was to collect large volumes of water, 100 liters, at each of three different depths in the main channel. We had hoped to do this last year, but our plan to pump the water immediately through filters on site turned out to be completely ineffective because the very fine particles in the Fraser immediately clogged our filters. Our approach this year was to simply pump the water on board the boat and transport it back to our “lab” to filter at our leisure (with our new and improved filtration units).

With the help of our boat captain Felix and mate Jeffrey, we spent the morning scouting out the best location (a stretch with a stable bottom and light enough ship traffic that we could drift while pumping). We waited until the afternoon to begin collecting water because we wanted a point in the day when the tide was not flooding (to maximize the outflow of the river against the inflow of the tide and because low current speeds during slackwater allow particles to settle!). Once we were on station, the pumping went brilliantly and in less than two hours, we had 380 liters of water on board. The extra 80 liters were a replicate to conduct an experiment with a precipitating agent (aluminum sulfate or “alum”) to see if this method could be used in the future to expedite the filtration process.

Now the real work begins! We spent Wednesday evening and all day Thursday filtering the depth samples. We are still working through the alum water in a race against the clock to pack up all our gear and samples for shipping tomorrow. Then we must bid farewell to our friends at UFV and return to WHOI, where we will have more samples in our hands than we’ll know what to do with! A huge thanks to everyone who made this campaign possible, in particular the folks at Port Metro Vancouver for generously offering the services of the P/V Port Fraser for our delta sampling, and our colleagues at UFV and their students, who will be continuing the time series sampling for another exciting year. See you next spring for the freshet!

Training Days

An important aspect of the Global Rivers Project is acquiring a time series. For weekly samples from the Fraser Basin, we are indebted to our colleagues at the University of Fraser Valley --- Steven Marsh, Sharon Gillies, Alida Janmaat, and seven of their brightest undergraduate students. Yesterday, we met up with them at Fort Langley to demonstrate the newest, streamlined sampling procedure. After being rained on, and having our equipment peed on (by a dog), we were delighted to retire to a real laboratory (as opposed to our motel bathroom) and have a dedicated workforce in waiting…

Undergraduate students! They took the reins, using the two pressurized filtration units to filter 60 L of water. Today, they helped us run the filtered water through resin-filled cartridges that catch dissolved organic matter (including lignin compounds). Back at WHOI, the organic matter will be eluted off the cartridges and the lignin compounds separated for radiocarbon analysis by Yvonne Feng (a postdoc with Tim Eglinton), to constrain the rate of terrestrial organic matter cycling within, and export from, the Fraser River watershed.

Amazingly, the UFV students have agreed to repeat this lengthy lignin extraction three times a year (at high, intermediate, and low flow) as part of the time series. A big thank you to these budding scientists.

It's not easy being ionic

The follow-up to yesterday’s exciting tale of organic chemicals features our inorganic measurements! Refer to the photo from yesterday’s post for visuals of the samples (but refer to the photo at right for the awesome conglomerate at our Lillooet sampling site!).

In the inorganic corner, we are collecting samples for “major ion” concentrations (elements with concentrations greater than 1ppm including calcium, potassium, sodium, chloride, magnesium, bromide, and strontium), nutrient concentrations (compounds required by photosynthetic algae and microbes including nitrate, nitrite, phosphate, ammonium, and silicate), trace metal concentrations and isotopes (elements with concentrations below 1ppm including manganese, chromium, copper, molybdenum, osmium, and rhenium), dissolved inorganic carbon (DIC) concentration and its ¹⁴C content, and the deuterium/hydrogen (²H/¹H or D/H) content of water.

Major ions and DIC can tell us a lot about what types of rock are being weathered within the drainage basin, and DIC together with its radiocarbon value can inform about the degree of air-water exchange that takes place during river transit and the contribution of “old” carbonate rock material. Nutrients serve the dual purpose of describing biological activity within the river, as well as possible contamination from industrial and agricultural activity (think of issues like the Mississippi River dead zone). Trace metal concentrations are another potential indicator of industrial contamination, while the radiogenic isotope systems of some of these elements are indicative of bedrock age and weathering processes. The deuterium content of riverwater is a climatic indicator of the temperature of the precipitation that contributes to the river’s discharge. Colder precipitation (higher latitude and/or altitude) has less deuterium, so the D/H we measure in the river tells us about the source of the water itself (glacial melt, local runoff, etc.).

Each of these samples has its special requirements for preservation and storage. Some require cold temperature and dark to prevent outgassing and photodegradation (nutrients, optical properties, incubations), others acidification to stop biological activity (DOC, DON). DIC samples are very sensitive to contact with atmospheric gases, so in addition to poisoning to kill bacteria, we must seal them in special glass bottles with fancy grease to ensure total cutoff from the outside world. Trace metal concentrations in river water are so low that contamination with small amounts of dust can give erroneous measurements, so these samples are collected in specially acid-cleaned plastic bottles and stored in plastic bags. You can imagine an instruction sheet for this protocol going on for many pages and requiring lots of equipment. But after a few stations, we developed a rhythm and we can now fill all our bottles in a matter of about an hour. And in truth, our vehicle is stuffed to the gills with our gear when travelling from one base lab station (hotel room) to the next. But in the end, our sampling is nicely streamlined in this second campaign and the high-quality samples we are collecting should provide a great foundation for establishing what is possible in other basins.

We are now almost to the delta in our downstream journey. Coming up: adventures in lignin extraction with UFV undergrads!

Looking beyond particles, or: How I learned to stop worrying and love the dissolved phase

We decided the time has come to describe some of the other samples we’re collecting and what they add to the global rivers project. Our protocol reads a bit like a laundry list of standard water chemistry measurements, which exemplifies the overarching goal of this project and the Fraser’s special role in achieving these objectives. The Fraser is in many ways the easy river in this project, as it presents the fewest logistical obstacles (compared to the rivers being studied in Siberia, the Congo, the Indian subcontinent, and China). Not only is it feasible to transit the entire basin by car in a few weeks, we have local collaborators to help us acquire equipment and chemicals and ship samples back to WHOI, and we can rely on electrical power in the towns we visit. For this reason, we are not generally limited by the type and number of samples we can collect, so we try to collect everything we can!

In addition to the suspended particle and bank sediments, our water samples (for dissolved constituents) can generally be divided into two groups: inorganic and organic quantities. Today’s post will cover organics. This group includes dissolved organic carbon (DOC) concentration, dissolved organic nitrogen (DON) concentration, and radiocarbon (¹⁴C) content of DOC. DOC and DON give us an idea of which tributaries are the major sources of organic matter to the total river flux, but adding carbon isotopes (¹³C and ¹⁴C) tells us much more about the nature of the carbon sources. Different types of biota imprint different stable isotopic signatures on the organic matter they produce (leading to distinctive ¹³C values for carbon produced by trees, grasses, and algae growing in the river), and radiocarbon values are determined by the age of the organic matter (giving different ¹⁴C values for old material, such as aged soils, and young material, such as recently deceased plants).

We also collect samples which WHRC scientists will analyze for optical properties of DOC (a quick measurement which can give lots of information about the different compounds making up very complex DOC) and bacterial incubations (which quantifies the “lability” or freshness/tastiness of DOC to bacteria). These detailed characterizations of what kind of compounds make up DOC are of particular interest in the Arctic watersheds, and potentially also here in B.C., where climate change and other anthropogenic effects are altering the upper soil and permafrost layers. If very old reservoirs of carbon are being mobilized and exported by rivers, the nature and magnitude of fluxes of terrestrial carbon to the ocean could be changing significantly on short (human) timescales. We will also be sampling for lignins (organic compounds specific to terrestrial plants), but that’s a topic for a later post! Stay tuned for the inorganic side of the story...

Edelweiss, Edelweiss

After a long stint in Prince George (sampling the Willow, McGregor, Nechako, and Blackwater tributaries), yesterday we departed for Quesnel, a quaint vacation town and former hub of the gold rush. Along the way, we stopped at a Fraser main stem sampling site along the Cariboo Highway. We came upon this site almost by chance last year when our original site turned out to be less than ideal. We cruised up the highway a bit and spotted a potential access point…

Somewhat to our surprise, we discovered that the proprietors of the Stone Creek RV park hailed from Germany. German connections have been a curiously frequent theme of this sampling trip. First of all, all three members of this year’s team speak German (notably including one native speaker). In addition, Tim Eglinton’s lab at WHOI (also involved in the world rivers project) is currently relocating to ETH in Switzerland. But we have also discovered that there is a particular Swiss/German influence in British Columbia, highlighted by small businesses such as this RV park, a Bavarian bakery in Lillooet, and a Swiss bakery in Valemount. It seems many Swiss and Germans came to this area over the past decades, and it is interesting to encounter their unique contributions to local culture. Today at the RV park, the owner chatted with us about his previous employment in Kitimat (a community on the coast of central B.C. created to sustain the Alcan aluminum smelter, powered by water diverted from the Nechako River) and the pulp mills in Prince George which dump their waste into the Fraser, giving the stretch of river flowing by his home a distinctive aroma and sudsy surface. He gave us Edelweiss flowers carved from tree twigs before we descended to the river to sample.

Today we sampled the Chilcotin River, a tributary flowing through the dry belt between the Coast Range and Cariboo/Rocky Mountains. This truly unique corner of B.C. features bunchgrass, bighorn sheep, and stunning sedimentary hoodoos. Again, history and local traditions imprint themselves on our scientific endeavors, as our sampling site included abandoned log cabins from bygone ranching days and sights of First Nations fishing points. But even a spot like this is not static. When we returned to this site today we discovered newly built structures, likely used for the local practice of air-drying salmon under tarps in the arid winds of this region. On our drive back to the highway, we spotted a group of bighorn sheep, which the surrounding nature preserve is intended to protect – a real treat! We also watched as countless lumber trucks rolled into the hillsides empty and back towards Williams Lake fully loaded. Not all the wildlife in the Cariboo are given special sanction.

A Homemade Laboratory

Each evening we transform a hotel room into a laboratory. First, we move four 19-liter jugs and five 4-liter cubitainers from the backseat of our SUV into the closet. These samples are filtered to collect suspended particles. Next we carry in the portable freezer, which contains water samples from each site. Freezing is the ideal method of preservation for certain samples, because it inhibits outgassing of volatile chemicals (such as ammonia) and degradation of organic matter by microbes. When we return to WHOI, we will thaw frozen water samples and have them analyzed for nutrients, which include phosphate, nitrate, nitrite, ammonium, and silicate. We also collect a suite of other water samples, some of which have specific preservation requirements (more on this later!).

The next step is setting up the filtration station in the bathroom. On top of a garbage can we set a filtration unit that was designed by our colleague Dr. Valier Galy and his PhD advisor, Dr. Christian France-Lanord. We pressurize the unit using a bicycle pump so that we can force a large volume of river water through a membrane (made of polyethersulfone) with openings of 0.2 microns (a micron is 1/1,000 of a millimeter. To understand just how small this is, consider that human hairs measure between 30 and 120 microns). We are most interested in the particulate matter trapped on the membrane, as oppose to the water that passes through the membrane (since we collect all the filtered water we need on station). By collecting the particulate matter at many sites during different flow conditions, we hope to develop a record of the spatial and temporal variability of the sediment load.

Tributaries take center stage

Friday morning we departed Valemount for Prince George, a drive of about 300km. Halfway through the journey through the Rocky Mountain Trench, our surroundings quickly changed from rugged foothills to rolling plains. Our good luck with the weather has continued – we’ve only been rained out of one site so far! But of course we couldn’t cover this much distance without collecting a few samples…

We are particularly interested in more carefully defining the source of a very unique radioisotope signature we measured in our samples from the headwaters last summer. We found strontium isotope values (⁸⁷Sr/⁸⁶Sr) indicative of very old bedrock. The Rocky Mountains are an old terrain, however this value was so extreme (“radiogenic,” meaning a long time has passed during which ⁸⁷Sr has been produced from the decay of ⁸⁷Rb), we want to determine whether its source is widespread in this area or can be traced to a particular watershed. So we stopped at five small tributaries during our drive for “quick stations,” where we collected samples only for strontium isotopes and nutrients. We hope that this more highly resolved picture of the subdrainage basins of the upper reaches will tell us more about how the Fraser acquires its chemical identity further downstream.

We are now spending a few days in Prince George, which will serve as our base for a number of sampling sites around the first big bend in the Fraser’s path as it breaks out of the mountains and begins its southward flow. The highway does not follow the river in this area, so we are testing our vehicle’s SUV status on long hauls over dirt roads! We have also accumulated large volumes of water for filtration, which will keep us busy for the next day or two…

To the source

After taking advantage of the last remnants of daylight yesterday to collect water from the Robson River for filtration back in Valemount, today the sampling began in earnest. We started off under hesitatingly sunny skies at the Mount Fitzwilliam trailhead for our furthest upstream station. We were fortunate to have good weather while working out the kinks of our regimen, and even took a quick sample from the outflow of Yellowhead Lake, one of only two lakes on the Fraser’s main stem.

The day turned overcast as we made our way back to our station on the Robson River, where the visitor’s center just closed for the season on Monday. A few intrepid late-season hikers stopped to say hello as we pumped water through our filters into the collection of bottles we bring to each station.

Fearing poor weather prospects for tomorrow and energized by our success with the first two stations, we decided to drive to McBride for a third. We were greeted on the banks of the now muddy Fraser with light rain, cold wind, and lovely exposed bank deposits.

We are spending our last night in Valemount filtering today’s large-volume samples. We hope to collect enough particulate matter on these filters to measure a suite of bulk chemical characteristics (organic carbon and nitrogen content, stable carbon and nitrogen isotopes, radiocarbon, and trace metal content). The Fraser is dominated by very fine particles, which makes trapping large quantities of suspended material difficult. One of the main goals of our project is to collect sufficient suspended organic matter to make compound- or compound class-specific radiocarbon measurements to better constrain the specific sources of organic matter within the drainage basin. Here in the headwaters, where the river is carrying mainly products of mineral erosion, we will likely only collect enough organic carbon for bulk analyses. But hope springs eternal!

Headwaters ahoy!

The 13 boxes of shipped equipment arrived at the University of the Fraser Valley only hours before us. To fit everything into our rental car, we had to jettison a few items (including the 3rd row of seats and a personal piece of luggage).

Now we’re off to Valemount, where we will be sampling the headwaters of the Fraser River. The idea is that over the course of our fieldwork we will follow the same 1,375 km journey as the river water, albeit a little slower.

The Fraser begins as tiny rivulets fed by melting glaciers, and swiftly-grows, carving its way through the Rocky Mountain trench before turning south through its steep canyon, and finally curving into the floodplain to drop its organic-rich sediment in the large delta near Vancouver.

Fraser Fun Facts:

• The Fraser is the largest salmon spawning river in the world, and 1 of only 3 rivers in which North America’s largest game fish, the white sturgeon, live.
  
  
• Construction on the Canadian Northern Railway in 1913 nearly decimated Fraser River salmon runs.
  
  
• The Fraser is the largest river in British Columbia, and the fifth largest river in Canada.
  
  
• The Fraser has no dams in its main stem.
  

The Adventure Begins

Welcome to our blog for the second field campaign to the Fraser River! This project is part of the National Science Foundation’s Emerging Topics in Biogeochemical Cycles initiative and aims to quantify the flux, age, and composition of terrestrial organic carbon transported by large rivers to the ocean. Rivers are a critical link between carbon removed from the atmosphere by land plants and its eventual sequestration in the global ocean. Processing of this carbon during weathering and biological activity within drainage basins impacts its fate once it reaches the ocean. The Fraser River provides a valuable testing ground for the tools used in this project to quantify these processes owing to its wide range of bedrock geology and vegetation type, in addition to the natural state of its main stem, which is undammed. This year’s sampling campaign will capture low-flow conditions. This is also an opportunity to strengthen ties with our collaborators at the University of the Fraser Valley (who have been collecting time series samples in the floodplain for the past year) and expand outreach activities through exhibits of artwork by local schoolchildren.