Claremar, B., Wällstedt, T., Rutgersson, A. & Omstedt, A. 2013: Deposition of acidifying and neutralising compounds over the Baltic Sea drainage basin between 1960 and 2006. Boreal Env. Res. 18: 425–445.
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Tolvanen, H., Suominen, T. & Kalliola, R. 2013: Annual and long-term water transparency variations and the consequent seafloor illumination dynamics in the Baltic Sea archipelago coast of SW Finland. Boreal Env. Res. 18: 446–458.
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Jaakkola, L. M., Heiskanen, M. M., Lensu, A. M. & Kuitunen, M. T. 2013: Consequences of forest landscape changes on the availability of winter pastures for reindeer (Rangifer tarandus tarandus) from 1953 to 2003 in Kuusamo, northeast Finland. Boreal Env. Res. 18: 459–472.
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Kaitaranta, J., Niemistö, J., Buhvestova, O. & Nurminen, L. 2013: Quantifying sediment resuspension and internal phosphorus loading in shallow near-shore areas in the Gulf of Finland. Boreal Env. Res. 18: 473–487.
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Flener, C. 2013: Estimating deep water radiance in shallow water: adapting optical bathymetry modelling to shallow river environments. Boreal Env. Res. 18: 488–502.
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Claremar, B., Wällstedt, T., Rutgersson, A. & Omstedt, A. 2013: Deposition of acidifying and neutralising compounds over the Baltic Sea drainage basin between 1960 and 2006. Boreal Env. Res. 18: 425–445.

This study produced a gridded database of acidifying and eutrophying deposition in the Baltic Sea and its drainage basin for the period 1960–2006. Data from various data sets were combined to generate monthly atmospheric (wet) deposition of cations (Ca²⁺, Mg²⁺, Na⁺, K⁺ and NH₄⁺) and anions (SO₄^2–, NO₃^– and Cl^–). Output of a chemical transport model and interpolated measurements were used, and when these were not available, trends and seasonal cycles were constructed from historical emissions and deposition data. These methods lose some spatial patterns, but the mean trends reflect the influence of east-European emissions more than earlier studies with more westerly-centred observations. The calculated depositions of sulphur, nitrogen and calcium (correlated with sulphur emission) increased from 1960 to 1990 and then decreased until 2006. The trend is most evident for sulphur with a 100% increase followed by a 73% decrease.

Tolvanen, H., Suominen, T. & Kalliola, R. 2013: Annual and long-term water transparency variations and the consequent seafloor illumination dynamics in the Baltic Sea archipelago coast of SW Finland. Boreal Env. Res. 18: 446–458.

The availability of photosynthetically active radiation (PAR) is one of the limiting factors of marine primary production. In coastal waters, the proportions of optical constituents vary, causing changes in water transparency, and consequently the rate of seafloor illumination. We illustrate this phenomenon geographically in seasonal and long-term perspectives on the archipelago coast of SW Finland in the Baltic Sea, using data from 21 Secchi measurement stations. The results indicate vast spatial and temporal variation of the proportion of illuminated seafloor area, which, in this study, is defined as the seafloor above the estimated euphotic depth (where over 1% of the surface PAR remains). The seafloor illumination undergoes an annual cycle, during which a quarter of the studied seafloor area is illuminated only for a part of the growing season. Based on long-term Secchi data, we estimate a 50% decrease in the total illuminated seafloor area from 1930 to 2007.

Jaakkola, L. M., Heiskanen, M. M., Lensu, A. M. & Kuitunen, M. T. 2013: Consequences of forest landscape changes on the availability of winter pastures for reindeer (Rangifer tarandus tarandus) from 1953 to 2003 in Kuusamo, northeast Finland. Boreal Env. Res. 18: 459–472.

Using aerial photographs, we examined the changes in the forest matrix from 1953 to 2003 in the Oulanka National Park and commercial forests in the northern part of the municipality of Kuusamo. The changes concerned the potential winter grazing grounds available to the existing reindeer population. The main changes in the commercial forests took place between 1953 and 1977, during which time the mean forest-patch size shrank by 65%, and the number of patches increased by 78%. From 1953 to 2003, the total area of epiphytic lichens and ground-lichen pastures decreased by 48.6%. The area of ground-lichen pastures decreased by 20%, and the area of common hair grass pastures doubled. The forest matrix transition in the commercial forests changed not only the spatial configuration and areas of different pasture patches, but also the grazing pressure at the remaining pasture sites. In the national park, the changes in grazing pressure were related only to the changes in numbers of reindeer. In general, the conditions of reindeer pastures are a result of interaction between different land-use components.

Kaitaranta, J., Niemistö, J., Buhvestova, O. & Nurminen, L. 2013: Quantifying sediment resuspension and internal phosphorus loading in shallow near-shore areas in the Gulf of Finland. Boreal Env. Res. 18: 473–487.

Sediment resuspension was quantified in shallow, sheltered and semi-exposed coastal areas in the Gulf of Finland. Cylindrical sedimentation traps were placed at six locations including emergent aquatic vegetation stands (Phragmites australis), submerged vegetations stands (Myriophyllum spicatum, Potamogeton pectinatus and Potamogeton perfoliatus) and unvegetated shallow (1–1.5 m) areas. During the study period (19 May–29 September 2009, sampling interval of two weeks), there was a seasonal development of macrophyte stands, as well as variation in suspended matter and sediment resuspension. The resuspension-inhibiting effect of macrophytes was found as decreasing resuspension values in concordance with the increasing macrophyte density during the growing season. However, measured phosphorus resuspension was highest among emergent macrophytes due to high concentration of phosphorus in sediments. A linear regression model for resuspension in shallow coastal areas was developed with which sediment resuspension rate may be predicted.

Flener, C. 2013: Estimating deep water radiance in shallow water: adapting optical bathymetry modelling to shallow river environments. Boreal Env. Res. 18: 488–502.

The effect of deep-water radiance on modelling bathymetry in shallow rivers using Lyzenga's algorithm was investigated. To this end, a new method for estimating deep-water radiance in the absence of deep water is presented. This parameter is necessary for applying Lyzenga's optical bathymetry model to aerial photographs and other forms of remotely sensed data. The estimation was tested in the Tana river in northern Finland where the variable in question could be measured as well as estimated, and also in one of the Tana's optically shallow tributaries, where it was necessary to estimate deep-water radiance. The results show that the estimated values are very similar to measured deep-water radiance values in the larger river, but the effect of deep-water radiance in very shallow water seems to be negligible. The new technique described in this paper allows the Lyzenga optical bathymetry model to be employed in clear-water optically-shallow rivers, where deep-water radiance cannot be measured in the field, which is precisely where Lyzenga's model is able to deliver the highest accuracy. The method also provides a reproducible, unbiased method for estimating deep-water radiance even in water deep enough to digitize it manually from remotely sensed data.