Juhani Virkanen

Effect of urbanization on metal deposition in the bay of Töölönlahti, Southern Finland

Abstract A sediment core from the Bay of Toolonlahti in the centre of Helsinki, Finland was analysed by a selective extraction method in order to examine the geochemical impacts of urbanization. Concentrations of Al, Ca, Cu, Fe, Mn and Zn in the extracts and total P and S were measured at intervals of 1 cm to a depth of 100 cm. The data were subjected to principal components analysis. Sedimentation rate was determined using 137Cs- and 14C-measurements and SCP-analysis and it varied from 0.4 to 0.6 mm·yr−1. Most of the background metal deposition in the basin is acid soluble. The intense eutrophication began around 1900 and is reflected in the sediment by a rise in the concentrations of S, P, organically bound Cu, Fe, Mn, Zn and hydroxide Zn, Total Al, Ca and Mn decrease towards the surface, probably because of dilution by organic inputs or by biogenic silica. The total Cu and Zn were high in the surface with a large proportion of labile forms.

Recent environmental changes in a naturally acidic rocky lake in southern Finland, as reflected in its sediment geochemistry and biostratigraphy

Paleolimnological methods are combined with statistical multivariate analyses (PCA and CCA) to study the effects of local environmental disturbances and changes in loading of atmospheric origin on water acidity and the physiochemical properties of the sediment in a small, naturally acidic rocky lake in southern Finland. The pH of the lake as calculated from the diatom flora increased by 0.9 pH units as a consequence of a forest fire in the catchment area at the turn of the last century, and the changes in the diatom assemblages point to an increase in dys(eu)trophy and turbulence. In terms of element influx (in µg cm-2 yr-1), the effects of the fire are seen in a slight increase in the accumulation of lithophilous elements. Diatom-inferred pH values decline upwards in the sediment, but do not regain the level recorded before the fire. This is attributed to reactions between Fe3+ and S, which has partly accumulated from the air as SO2-, producing internal alkalinity. Accumulation rates of many elements increase markedly after the 1960s, an effect for Al, Mg, Na, P and Zn may be connected mainly with the enhanced accumulation of dry matter, whereas the accumulation of K, Ni, Pb, Ti and V in surface sediment are obviously related to atmospheric loading. Measured accumulation rates of Cd and Cu are lower than the calculated values especially in the surface sediment, possibly because of diagenetic changes. Accumulation of Ca and Mn decreases towards the surface on account of acidification of anthropogenic origin.

Ethanol Inhibits Activation of NLRP3 and AIM2 Inflammasomes in Human Macrophages–A Novel Anti-Inflammatory Action of Alcohol

Objective In the pathogenesis of coronary atherosclerosis, local macrophage-driven inflammation and secretion of proinflammatory cytokines, interleukin-1β (IL-1β) in particular, are recognized as key factors. Moderate alcohol consumption is associated with a reduced risk of coronary artery disease mortality. Here we examined in cultured human macrophages whether ethanol modulates the intracellular processes involved in the secretion of IL-1β. Results Ethanol decreased dose-dependently the production of mature IL-1β induced by activators of the NLRP3 inflammasome, i.e. ATP, cholesterol crystals, serum amyloid A and nigericin. Ethanol had no significant effect on the expression of NLRP3 or IL1B mRNA in LPS-primed macrophages. Moreover, secretion of IL-1β was decreased in parallel with reduction of caspase-1 activation, demonstrating that ethanol inhibits inflammasome activation instead of synthesis of pro-IL-1β. Acetaldehyde, a highly reactive metabolite of ethanol, had no effect on the ATP-induced IL-1β secretion. Ethanol also attenuated the secretion of IL-1β triggered by synthetic double-stranded DNA, an activator of the AIM2 inflammasome. Ethanol conferred the inhibitory functions by attenuating the disruption of lysosomal integrity and ensuing leakage of the lysosomal protease cathepsin B and by reducing oligomerization of ASC. Conclusion Ethanol-induced inhibition of the NLRP3 inflammasome activation in macrophages may represent a biological pathway underlying the protective effect of moderate alcohol consumption on coronary heart disease.

A long-term record of human impacts on an urban ecosystem in the sediments of Töölönlahti Bay in Helsinki, Finland

Ecological impacts of urbanization are receiving increasing scientific attention, yet few data sets permit long-term effects on terrestrial and aquatic ecosystems to be assessed. Toolonlahti Bay, in the centre of Helsinki, Finland, provided on opportunity to characterize recent human impacts especially by means of chemical and biostratigraphical analyses of a sediment core. Periods of coniferous forest, forest clearance, urbanization and the development of parks, can be distinguished in the pollen record of the core. Palynological diversity was highest before the forest clearance at the turn of the century. The character of the sediment and the water have changed substantially in response to rapid population growth, the construction of sewage systems and building within the catchment of the bay. This is reflected in marked increases in organic matter, phosphorus and heavy metal (Cd, Cu, Ni, Zn and Pb) concentrations between 1890 and 1960, accompanied by a rapid increase in diatom species indicative of eutrophication and a decline in diatom species diversity. Since the cessation of waste-water disposal in the 1960s, concentrations of a number of pollutants have declined and water quality has gradually improved, but conditions are still affected by internal and atmospheric loadings. As a consequence of land uplift (2 mm per year) and the rapid sedimentation rate (6 mm per year), the volume of the bay is decreasing. Within 200 years, the shallow bay, which is skirted by extensive parks and famous cultural buildings such as the Finlandia and the Opera Houses, will fill with sediment unless it is dredged.

The effects of natural environmental changes on sedimentation in Lake Kuttanen, a small closed lake in Finnish Lapland

A sediment core from Lake Kuttanen, a small closed lake in Finnish Lapland, was investigated to determine the effects of Holocene water-table changes, aeolian activity and forest fires on sediment physical properties and sediment geochemistry. Sediment properties were examined by water content, loss-on-ignition (LOI) and dry matter sedimentation rate analyses. Sediment geochemistry was studied by determining the acid-soluble accumulation rates of Al, Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn. The Fe/Mn ratio was calculated to study changes in the redox potential and charcoal concentrations were measured to determine the occurrence of local and regional fires. The sediment accumulation rate was determined using 14C and b-activity measurements. Principal components analysis (PCA) was used to examine variations within the data and intercorrelations among the variables. After the isolation of the basin, all the element accumulation values were high because of the erosional supply from the catchment before stable soil formation. During the supposed termination of the early Holocene dry and warm period (6000–4000 cal. BP) the element and dry matter accumulation values decreased and LOI increased rapidly. The sedimentation rate increased gradually and the element accumulation values began to increase after 4000 cal. BP along with the increase in dry matter accumulation. The accumulation of Fe was affected also by chemical mobilization from the soils. The LOI values decrease gradually towards the sediment surface, suggesting higher water levels, increasing aeolian activity on a regional scale and dilution by Fe supply from the catchment soils. About 900 cal. BP this activity began locally very near the lake. Charcoal analysis shows that forest fires were a common feature on a regional scale. Their geochemical impact is somewhat unclear; perhaps because most were of little or no geochemical significance, which may have been related to the properties of the permeable soil of the catchment. The fires around 1600 and 900 cal. BP probably triggered the aeolian activity near the lake, which has led to the mobilization of Fe from the catchment, and reverse datings in the 14C analysis. Thus, natural environmental changes can cause rapid sedimentological and geochemical changes. The main force behind the changes appears to be climatic.

Hemin and Cobalt Protoporphyrin Inhibit NLRP3 Inflammasome Activation by Enhancing Autophagy: A Novel Mechanism of Inflammasome Regulation

Inflammasomes are intracellular protein platforms, which, upon activation, produce the highly proinflammatory cytokines interleukin (IL)-1β and IL-18. Heme, hemin and their degradation products possess significant immunomodulatory functions. Here, we studied whether hemin regulates inflammasome function in macrophages. Both hemin and its derivative, cobalt protoporphyrin (CoPP), significantly reduced IL-1β secretion by cultured human primary macrophages, the human monocytic leukemia cell line and also mouse bone marrow-derived and peritoneal macrophages. Intraperitoneal administration of CoPP to mice prior to urate crystal-induced peritonitis alleviated IL-1β secretion to the peritoneal cavity. In cultured macrophages, hemin and CoPP inhibited NLRP3 inflammasome assembly by reducing the amount of intracellular apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC). The reduction of ASC was associated with enhanced autophagosome formation and autophagic flux. Inhibition of autophagy prevented the CoPP-induced depletion of ASC, implying that the depletion was caused by increased autophagy. Our data indicate that hemin functions as an endogenous negative regulator of the NLRP3 inflammasome. The inhibition is mediated via enhanced autophagy that results in increased degradation of ASC. This regulatory mechanism may provide a novel approach for the treatment of inflammasome-related diseases.

Calpain Activity Is Essential for ATP-Driven Unconventional Vesicle-Mediated Protein Secretion and Inflammasome Activation in Human Macrophages

Extracellular ATP is an endogenous danger signal that is known to activate inflammatory responses in innate immune cells, including macrophages. Activated macrophages start to secrete proteins to induce an immune response, as well as to recruit other immune cells to the site of infection and tissue damage. In this study, we characterized the secretome (i.e., the global pattern of secreted proteins) of ATP-stimulated human macrophages. We show that ATP stimulation activates robust vesicle-mediated unconventional protein secretion, including exosome release and membrane shedding, from human macrophages. Pathway analysis of the identified secreted proteins showed that calpain-related pathways were overrepresented in the secretome of ATP-stimulated cells. In accordance with this, calpains, which are calcium-dependent nonlysosomal cysteine proteases, were activated upon ATP stimulation through a P2X purinoceptor 7 receptor–dependent pathway. Functional studies demonstrated that calpain activity is essential for the P2X purinoceptor 7 receptor–mediated activation of unconventional protein secretion. Unconventional protein secretion was followed by cell necrosis and NLRP3 inflammasome–mediated secretion of the mature form of the proinflammatory cytokine IL-1β. Furthermore, ATP-driven NLRP3 inflammasome activation was also dependent on calpain activity. Interestingly, pro–IL-1β and inflammasome components ASC and caspase-1 were released by ATP-activated macrophages through a vesicle-mediated secretion pathway. In conclusion, to our knowledge, we provide the first global characterization of proteins secreted by ATP-activated human macrophages and show a pivotal role for calpains in the activation of the inflammatory response during ATP exposure.

Metal Distribution in Lakes Surrounding the Kostomuksha Iron Mine and Ore Dressing Mill in Northwestern Russia

Metal distributions in lakes surrounding Kostomuksha iron mine and ore dressing mill were explored to study the effects of the mill on the state of the lakes. Both surface water and 10 cm sediment core samples were taken from six lakes in the Russian side and another two in the Finnish side at a maximum distance of 70 kilometres from the plant. Concentrations of thirteen metals, phosphorus and sulphur were determined in waters and sediments by ICP-MS after filtration of the water samples and acid digestion of the sediment samples. No increase of these elements was observed in lakes in southwestern direction towards Finland where air transport was the only pathway. In the northwestern direction where there are also water releases from a waste pond of the plant increasing concentrations of Ca, Mn, S, Fe and As towards the plant were seen both in water and sediments phases. This was also the trend for Na, K and Mg in water and for Zn, Pb, Cd and Hg in the sediment. No systematic change was seen in case of Al, P and Ni. It is likely that elevated water concentrations of at least K, S and As are due to water releases from the waste pond but for other elements the source is not quite evident.