Coastal marine environments are critical transitional zones between the continents and the oceans. They are also strongly impacted by human activities on land and at sea. Understanding the cycling of carbon, nutrients and other elements in coastal environments means studying inputs from land, uptake in and release from biomass, and burial in sediments. Elements are transformed by numerous processes whose interactions eventually control water quality and the health of coastal ecosystems. Our research focuses on biogeochemical processes in sediments, where organic matter is broken down by microbes, releasing nutrients and methane.
SOFTDRINK is a Research Council of Finland-funded project awarded to Tom Jilbert in collaboration with
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Through an Research Council of Finland Fellowship to Tom Jilbert (2018-2023), the group studies the accumulation of trace metals (e.g. molybdenum, uranium, cadmium, lead, tin, zinc) in coastal sediments. These metals can be used as indicators of human impacts and hence to provide information on past environmental conditions in areas where monitoring records are sparse. Some trace metals from seawater can become naturally enriched in sediments under anoxic conditions, hence in areas of human-induced deoxygenation, sediment trace metal contents provide a record of historical oxygen concentrations. At the same time, other metals provide a record of direct pollution inputs to coastal systems. We study the mechanisms of enrichment of each metal and historical changes in their accumulation. This work is mainly focused on the Baltic Sea, Black Sea and other human impacted areas of the European coastal zone.
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Our group participates in the
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Freshwater systems worldwide are under intense pressure from human activities, including nutrient loading, industrial pollution and overfishing. Eutrophication is the dominant stressor in most lake ecosystems, caused by inputs of nitrogen and phosphorus from populated catchment areas. Eutrophication is exacerbated by processes in sediments that retain and recycle nutrients within the aquatic system, leading to so-called internal loading. Many lake ecosystems are now the subject of attempts to restore good water quality and usability of ecosystem services. At the same time, the importance of lakes as carbon sinks is being increasingly recognized. Our research focuses on understanding the timescales of internal loading following eutrophication, developing practical approaches to reduce sediment phosphorus pools, and understanding the role of lakes in carbon burial.
Boreal lake sediments may be a hitherto underestimated long-term sink for carbon. Organic matter from both autochthonous (in-lake) and allochthonous (external) sources accumulates in lake sediments and may be sequestered (buried) on geological timescales. Similarly to forests and soils, this carbon sink function of lakes is an important consideration for authorities planning carbon-neutral management strategies on various scales. In shallow boreal lakes, carbon can accumulate in near-shore areas associated with macrophyte stands, as well as open water areas where fine-grained sediments are focused into bathymetric depressions. In the project BlueLakes funded by the EU
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Through funding from a range of sources (Vesijärvi Foundation, LUVY, Hyvinkään kaupunki, Nurmijärven kunta) the group has been studying long-term accumulation and recycling of phosphorus in eutrophic lakes. Phosphorus is a key limiting nutrient for primary production and its accumulation in lake sediments is the main cause of internal loading. A host of microbial and geochemical processes control what happens to phosphorus after its has accumulated in the sediments, including release from organic matter, uptake into sedimentary minerals, and permanent burial. The latest project is a collaboration with Länsi Uudenmaan Vesi ja Ympäristö (LUVY) and focuses on establishing the downstream transport and cycling of phosphorus in the Siuntio river catchment in southern Finland
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Hypolimnetic withdrawal is a restoration technique in which phosphorus is removed from lakes through pumping of nutrient-rich deep water. In a pilot currently being tested in Lahti, Finland (combined funding from Finnish Environment Ministry, Hämeen ELY-keskus, Maa ja vesitekniikan tuki, Renlund Foundation), a closed circuit version of the technique allows phosphorus to be extracted by filtration. Our group studies optimization of the pumping and filtration system for maximum efficiency of phosphorus extraction. This includes studying seasonal cycles of phosphorus dynamics in the lake itself, as well as the oxidation and precipitation processes occurring in the filtration systems.
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