The Arctic Great Rivers Observatory (Arctic-GRO) project will assess river constituent (chemistry, isotopes, nutrients) fluxes and discharge in the Ob', Yenisey, Lena, Kolyma, Yukon and Mackenzie Rivers. These observations will be used to test hypotheses about the magnitude, controls and ecological significance of these fluxes, and will provide new information on inter-annual variability and trends in the major fluxes of constituents to the Arctic Ocean. By measuring the flux of water and constituents in these key rivers at the junction between the continents and the Arctic Ocean, it is possible to efficiently assess changes occurring across vast regions of the continents that may diagnose environmental change on land, and forecast imminent changes in circulation and biogeochemical processes in the Arctic and North Atlantic oceans. Monitoring the great arctic rivers is an essential component of any comprehensive Arctic Observatory program and is critical for understanding environmental change in the Arctic, a goal of SEARCH. The data collection will represent a pulse of activity within the IPY timeframe and will provide a legacy of data for future investigations. Arctic-GRO is based upon strong scientific collaborations among US, Canadian and Russian scientists. It also represents a major component of the Arctic Circumpolar Coastal Observatory Network (ACCO-Net), an overarching IPY initiative designed to link key coastal erosion monitoring sites established as part of the international Arctic Coastal Dynamics project with major arctic river sampling sites established as part of the NSF Freshwater Integration (FWI) study. The project will link with and extend the Student Partners Project, a science and education effort involving K-12 students and their teachers at each sampling site. Teachers and their students are educated in global change and in turn collect river samples of selected constituents at higher frequencies than would otherwise be possible, thereby improving the science.
project, funded by the US National Science Foundation (NSF) as part of the Arctic Observing Network (AON), is a collaboration among scientists and institutions from the United States, the Russian Federation, and Canada. Although the first installment of Arctic-GRO (2008-2012) is now complete, the project is ongoing, and has received renewed funding from NSF (Arctic-GRO II) beginning January 2012. Arctic-GRO (and, its predecessor, the PARTNERS Project) measures the flow of water-borne constituents in the six Great Arctic Rivers: the Ob', Yenisey, Lena, and Kolyma rivers in Siberia, and the Yukon and Mackenzie rivers in North America (Figure 1). Together, these rivers deliver more than two-thirds of the continental fresh water that is carried from land to the Arctic Ocean, which is the most landlocked and freshwater dominated of all the Earth's oceans. Understanding the chemistry of these large Arctic rivers is important for two major reasons. First, rivers can serve as sentinels of change that may be occurring across broad spatial scales, because changes occurring on land are captured by the water that flows across it, which is ultimately delivered to the aquatic environment. This is particularly important in the Arctic, where thawing permafrost and changes in vegetation are fundamentally affecting the Arctic system. In addition to this, however, the chemical composition of large rivers critically influences the chemistry and biology of coastal waters, and can also be used to track the movement of water within the Arctic Ocean. For these reasons, we chose our sampling sites to be as close to the Arctic Ocean as feasible (Figure 1), ensuring that the water we measure represents runoff from the broadest area of land possible, while at the same time accurately representing the chemical composition of the river water that empties into the Arctic Ocean. Before the advent of Arctic-GRO / PARTNERS, our ability to quantify the chemistry of the water flowing from land to the Arctic Ocean was severely hampered by a lack of seasonal coverage, the absence of common methodologies among rivers, and in some cases, poor data quality. These projects now ensure that the six largest Arctic rivers are sampled year-round, using common, reproducible field methodologies. Collected samples are all returned to the United States, where they are sent to specialist laboratories for analysis. Arctic-GRO samples are analyzed for a wide suite of chemical properties, including dissolved and particulate carbon and nutrients (nitrogen, phosphorus), carbon age, carbon and nitrogen stable isotopes which are used to assess the source of these materials, and major and trace ions. Project data are electronically published on the AON central data repository (www.aoncadis.org), and on the Arctic-GRO website (www.arcticgreatrivers.org), which also provides a project overview and lists project-related publications. Over the course of the Arctic-GRO project, the data we collect has been used by project scientists, collaborators, and researchers that are not affiliated with the project to make several major advances that have helped us to better understand the functioning of the Arctic system as a whole. These include: Calculating the amount of organic carbon and nutrients that are carried by rivers to the Arctic Ocean, and showing that these fluxes are much larger than previously suspected. Estimating the importance of riverine nitrogen for photosynthesis in the nearshore Arctic Ocean. Tracing how dissolved organic carbon moves through the Arctic Ocean, and calculating how quickly this land-derived carbon is broken down to CO2. Estimating the rate of CO2 fixation caused by the chemical weathering of rocks within these large Arctic watersheds. Finally, Arctic-GRO has had a continued emphasis on training and teaching, and has focused its efforts towards this end across a broad spectrum that ranges from university undergraduate and graduate students, to postdoctoral scientists, to the community members who live on the shores of these rivers and routinely help with, and are trained in, techniques for proper scientific sampling. The project is also unique in that it has created a tri-national (US-Russia-Canada) collaboration that has been ongoing for a decade, and facilitates the rigorous, quality controlled sampling of these major rivers. The project has also built a strong, collaborative network across multiple US institutions, which includes the Woods Hole Research Center, Marine Biological Laboratory, University of Texas at Austin, Yale University, Woods Hole Oceanographic Institution, and US Geological Survey. These multi-national and domestic partnerships will help to ensure our continued ability to understand this important component of the Arctic system, at an international level, for years to come.
