Catchment and lake network modify export of anaerobic oxidation capacity in boreal freshwaters.

Anaerobic terminal electron acceptors (aTEAs, i.e. NO, Fe, SO) enable anaerobic respiration, and each has a specific ability to oxidize reduced compounds.

Efficient protection of the Baltic Sea needs a revision of phosphorus metric.

Eutrophication of the Baltic Sea is driven by phosphorus and nitrogen. While the anthropogenic point source loads of both nutrients have decreased markedly, further reductions are needed. This is true particularly for phosphorus, as highlighted by its stringent abatement targets in HELCOM's Baltic Sea Action Plan.

Diffuse sources dominate the sulfate load into Finnish surface waters.

Sulfate (SO) affects the cycling of ecologically important substances, such as carbon, nutrients and metals, but the contribution of anthropogenic activities in sulfate load entering aquatic systems is poorly known. We calculate specific sulfate loads for land cover types, atmospheric deposition and point sources, and then estimate the source-specific flux of sulfate to Finnish surface waters. The largest sulfate flux, entering mostly the Baltic Sea, originates from agricultural fields on acid sulfate soil (24% of total flux).

Runoff changes have a land cover specific effect on the seasonal fluxes of terminal electron acceptors in the boreal catchments.

Climate change influences the volume and seasonal distribution of runoff in the northern regions. Here, we study how the seasonal variation in the runoff affects the concentrations and export of terminal electron acceptors (i.e.

Labile organic carbon regulates phosphorus release from eroded soil transported into anaerobic coastal systems.

Coastal eutrophication is expected to increase due to expanding and intensifying agriculture which causes a large amount of soil-associated P to be transported into aquatic systems. We performed anaerobic long-term incubations on field soil to mimic the conditions that eroded soil encounters in brackish sediments. The release of P from soil increased with the amount of labile organic C (acetate) addition and decreased with the soil/solution ratio.

Does control of soil erosion inhibit aquatic eutrophication?

Much of the phosphorus (P) from erosive soils is transported to water bodies together with eroded soil. Studies clarifying the impact of soil erosion on eutrophication have sought largely to quantify the reserves of P in soil particles that can be desorbed in different types of receiving waters. Aquatic microbiology has revealed that the cycling of P is coupled to the availability of common electron acceptors, Fe oxides and SO₄, through anaerobic mineralization in sediments.

Coastal eutrophication thresholds: a matter of sediment microbial processes.

In marine sediments, the major anaerobic mineralization processes are Fe(III) oxide reduction and sulfate reduction. In this article, we propose that the two alternative microbial mineralization pathways in sediments exert decisively different impacts on aquatic ecosystems. In systems where iron reduction dominates in the recently deposited sediment layers, the fraction of Fe(III) oxides that is dissolved to Fe(II) upon reduction will ultimately be transported to the oxic layer, where it will be reoxidized.

Contamination of River Kymijoki sediments with polychlorinated dibenzo-p-dioxins, dibenzofurans and mercury and their transport to the Gulf of Finland in the Baltic Sea.

Kymijoki, the fourth largest river in Finland, has been heavily polluted by pulp mill effluents as well as the chemical industry. Up to 24,000 ton of wood preservative, chlorophenol known as Ky-5, was manufactured in the upper reaches of the river, an unknown amount of which was discharged into the river between 1940 and 1984. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) occurred as impurities in the final Ky-5 product.