Carl-Magnus Mörth

Landscape‐scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network

Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network

Management Options and Effects on a Marine Ecosystem: Assessing the Future of the Baltic

Abstract We are using the coupled models in a decision support system, Nest, to evaluate the response of the marine ecosystem to changes in external loads through various management options. The models address all the seven major marine basins and the entire drainage basin of the Baltic Sea. A series of future scenarios have been developed, in close collaboration with the Helsinki Commission, to see the possible effects of improved wastewater treatment and manure handling, phosphorus-free detergents, and less intensive land use and live stocks. Improved wastewater treatment and the use of phosphorus-free detergents in the entire region would drastically decrease phosphorus loads and improve the marine environment, particularly the occurrence of cyanobacterial blooms. However, the Baltic Sea will remain eutrophic, and to reduce other effects, a substantial reduction of nitrogen emissions must be implemented. This can only be obtained in these scenarios by drastically changing land use. In a final scenario, we have turned 50% of all agricultural lands into grasslands, together with efficient wastewater treatments and a ban of phosphorus in detergents. This scenario will substantially reduce primary production and the extension of hypoxic bottoms, increase water transparency in the most eutrophied basins, and virtually eliminate extensive cyanobacterial blooms.

Hydrological alterations with river damming in northern Sweden: Implications for weathering and river biogeochemistry

Hydrological alterations with river damming in northern Sweden : Implications for weathering and river biogeochemistry

Hydrogeochemistry of sulfur isotopes in the Kalix River catchment, northern Sweden

Abstract The34S-to-32S ratio in dissolved SO4 has been studied in the Kalix River, Northern Sweden, and its catchment. Weekly sampling over 17 months revealed temporal variations from +5.3‰ up to +7.4‰ in the δ34S values in the river. Snow and rain samples showed lower δ34S values (average +5.6‰ and +5.0‰, respectively). The atmosphere is the major source for S in surface waters in the catchment, and the heavier δ34S values in the river are a result of SO4 reduction within the catchment. Most of the temporal variations in the δ34S value in the river are caused by a mixing of water from the mountain areas (relatively light δ34S) and the woodland. The δ34S value is relatively heavy in the woodland tributaries because of bacterial SO4 reduction in peatland areas influenced by groundwater. The highest δ34S values were measured during the spring flood, in June and in November. These heavy δ34S values are related to different types of water with diverse origins. The heavy δ34S values coinciding with the early spring flood originate from peatland areas in the woodland. Relatively heavy δ34S values (up to +14.4‰) were registered in mire water. Smaller variations of the δ34S value during summer and early autumn most likely were caused by the input of ground-mire water during heavy rains. A correlation between increased TOC concentrations and increased δ34S values was observed. The heavy δ34S values in June and November probably originate from SO4 reduction in bottom water and sediments in lakes within the catchment. Bottom water, enriched in34S SO4, was transported in the river during the spring and autumn overturn.

Dissolution of microcline and labradorite in a forest O horizon extract : the effect of naturally occurring organic acids.

Dissolution of microcline and labradorite in a forest O horizon extract : the effect of naturally occurring organic acids.

Hydrogeochemical contrast between brown and grey sand aquifers in shallow depth of Bengal Basin: consequences for sustainable drinking water supply.

Delineation of safe aquifer(s) that can be targeted by cheap drilling technology for tubewell (TW) installation becomes highly imperative to ensure access to safe and sustainable drinking water sources for the arsenic (As) affected population in Bengal Basin. This study investigates the potentiality of brown sand aquifers (BSA) as a safe drinking water source by characterizing its hydrogeochemical contrast to grey sand aquifers (GSA) within shallow depth (<70 m) over an area of 100 km(2) in Chakdaha Block of Nadia district, West Bengal, India. The results indicate that despite close similarity in major ion composition, the redox condition is markedly different in groundwater of the two studied aquifers. The redox condition in the BSA is delineated to be Mn oxy-hydroxide reducing, not sufficiently lowered for As mobilization into groundwater. In contrast, the enrichments of NH(4)(+), PO(4)(3-), Fe and As along with lower Eh in groundwater of GSA reflect reductive dissolution of Fe oxy-hydroxide coupled to microbially mediated oxidation of organic matter as the prevailing redox process causing As mobilization into groundwater of this aquifer type. In some portions of GSA the redox status even has reached to the stage of SO(4)(2-) reduction, which to some extent might sequester dissolved As from groundwater by co-precipitation with authigenic pyrite. Despite having low concentration of As in groundwater of the BSA the concentration of Mn often exceeds the drinking water guidelines, which warrants rigorous assessment of attendant health risk for Mn prior to considering mass scale exploitation of the BSA for possible sustainable drinking water supply.

Modeling riverine nutrient transport to the Baltic Sea: A large-scale approach

Abstract We developed for the first time a catchment model simulating simultaneously the nutrient land-sea fluxes from all 105 major watersheds within the Baltic Sea drainage area. A consistent modeling approach to all these major watersheds, i.e., a consistent handling of water fluxes (hydrological simulations) and loading functions (emission data), will facilitate a comparison of riverine nutrient transport between Baltic Sea subbasins that differ substantially. Hot spots of riverine emissions, such as from the rivers Vistula, Oder, and Daugava or from the Danish coast, can be easily demonstrated and the comparison between these hot spots, and the relatively unperturbed rivers in the northern catchments show decisionmakers where remedial actions are most effective to improve the environmental state of the Baltic Sea, and, secondly, what percentage reduction of riverine nutrient loads is possible. The relative difference between measured and simulated fluxes during the validation period was generally small. The cumulative deviation (i.e., relative bias) [Σ(Simulated − Measured)/ΣMeasured × 100 (%)] from monitored water and nutrient fluxes amounted to +8.2% for runoff, to −2.4% for dissolved inorganic nitrogen, to +5.1% for total nitrogen, to +13% for dissolved inorganic phosphorus and to +19% for total phosphorus. Moreover, the model suggests that point sources for total phosphorus compiled by existing pollution load compilations are underestimated because of inconsistencies in calculating effluent loads from municipalities.

Metal transport in the boreal landscape-the role of wetlands and the affinity for organic matter.

Stream water concentrations of 13 major and trace elements (Al, Ba, Ca, Cr, Cu, La, Mg, Na, Ni, Si, Sr, U, Y) were used to estimate fluxes from 15 boreal catchments. All elements displayed a significant negative correlation to the wetland coverage, but the influence of wetlands was stronger for organophilic metals; 73% of the spatial differences in the normalized element fluxes could be explained based only on the wetland coverage and the affinity for organic matter, which was quantified using thermodynamic modeling. When the analysis was restrained to the smaller streams (<10 km(2)) the explanatory power increased to 88%. The results suggest that wetlands may decrease the fluxes of metals from boreal forests to downstream recipients by up to 40% at otherwise similar runoff. We suggest that the decrease in element fluxes is caused by a combination of low weathering in peat soils and accumulation of organophilic metals in peat. The model could not explain the spatial patterns for some metals with low affinity for organic matter, some redox-sensitive metals, and some metals with exceptionally high atmospheric deposition, but the results still demonstrate that wetlands play an important role for the biogeochemical cycling of many metals in the boreal landscape.

Modeling hydrology and silicon‐carbon interactions in taiga and tundra biomes from a landscape perspective: Implications for global warming feedbacks

Modelling hydrology and silicon-carbon interactions in taiga and tundra biomes from a landscape perspective : Implications for global warming feedbacks

Modeling Social—Ecological Scenarios in Marine Systems

Human activities have substantial impacts on marine ecosystems+ including rapid regime shifts with large consequences for human well-being. We highlight the use of model-based scenarios as a scientific tool for adaptive stewardship in the face of such consequences. The natural sciences have a long history of developing scenarios but rarely with an in-depth understanding of factors influencing human actions. Social scientists have traditionally investigated human behavior, but scholars often argue that behavior is too complex to be represented by broad generalizations useful for models and scenarios. We address this scientific divide with a framework for integrated marine social-ecological scenarios, combining quantitative process-based models from the biogeochemical and ecological disciplines with qualitative studies on governance and social change. The aim is to develop policy-relevant scenarios based on an in-depth empirical understanding from both the natural and the social sciences, thereby contributing to adaptive stewardship of marine social-ecological systems.