Today, Earth Day, is an appropriate conclusion to this chapter of the Fraser River expedition. As I unpack the information held in these samples over the coming months, I hope to learn about how this river transmits the products of photosynthesis and respiration on land to the coastal ocean. What sort of role does the Fraser play in global exchanges of carbon between the air, rocks, plants, soil, and water? How will these processes change in the future as the Earth warms? For rivers, which cross the boundaries between land, ocean, and atmosphere, answering these questions has never been more important. Luckily, working on these problems also happens to be a lot of fun.
After two weeks of almost uninterrupted grey weather, even the stubborn locals here started to stay indoors. Thursday and Friday introduced me to a new experience: I finished sampling without a visit from a single rower, canoe team, or wandering dog-walker. Fort Langley felt deserted, save for the occasional passing freight train. Then suddenly, the sun returned and this afternoon the town was abuzz with shoppers, gelato-fueled children, and everyone else with an acute vitamin D deficiency within a 5-mile radius. But the sampling dock was still a peaceful haven with the quiet hum of the river and phenomenal views of the nearby mountains.
On Saturday, the whole UFV team came out for one last group sampling session. The skies defied the forecast and spared us from getting drenched. We celebrated our luck by posing for a few group photos. My ultra-high-frequency sampling is drawing to a close, but the students will keep coming out every week or two. My early-freshet samples have hopefully captured the rapid pulse of DOC in exciting detail, and the sampling throughout the summer will characterize the bulk of the year’s other chemical fluxes.
In the span of only a few short weeks, I’ve watched the water flow of the Fraser increase to about 3x its winter baseline level. Turbidity (or muddiness) has spiked twice, maxing out at over 20 times its initial value. Dissolved organic carbon concentration, according to the fluorescent probe, has approximately tripled. The other more nuanced changes will have to wait for sample analysis to be revealed. I can’t wait to see what these samples have to tell us about how the chemistry of the Fraser River responds to the transition into summer!