Boreal Rivers as Sources of Terpenoid Emissions.

Area of Science:

• Environmental Science
• Biogeochemistry
• Ecology

Background:

• Inland waters, particularly rivers, are recognized as significant sources of CO2 emissions.
• The contribution of rivers to biogenic volatile organic compound (BVOC) emissions, specifically terpenoids, is not well-established.

Purpose of the Study:

• To quantify terpenoid emissions from two boreal rivers in Finnish Lapland.
• To investigate the seasonal variability and drivers of these emissions.
• To assess the significance of boreal rivers as BVOC sources in a global context.

Main Methods:

• Quantification of monoterpene and sesquiterpene emissions from two boreal rivers over two growing seasons.
• Monthly observations were conducted in peatland and upland mineral soil catchments.
• Analysis of relationships between emissions and environmental factors like dissolved organic carbon and air temperature.

Main Results:

• Both rivers were identified as significant sources of terpenoid emissions, with mean annual emissions of monoterpenes (4.9 ± 2.8 mg m⁻² year⁻¹) and sesquiterpenes (1.2 ± 0.8 mg m⁻² year⁻¹).
• Emissions exhibited seasonal variation and were comparable to those from boreal forest floors.
• Dissolved organic carbon concentrations and air temperature were key drivers of emission variability, with distinct patterns observed between clearwater and brownwater rivers.

Conclusions:

• Boreal lotic ecosystems represent a substantial source of terpenoid emissions.
• Terpenoid emissions from these rivers are comparable to other major ecosystems.
• The findings highlight the need to incorporate riverine terpenoid emissions into global BVOC budgets.