Natural isotopes support groundwater origin as a driver of mire type and biodiversity in Slitere National Park, Latvia

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Artificial Recharging of Ground Water Resources Experience in Well Field “Baltezers” (Latvia)

In several well fields in the region Baltezers the Quaternary shallow groundwater with artificial groundwater recharge system is used For Riga city water supply. A Hidrogeological modelling and field investigation was done to asses the risk for groundwater quality and for optimisation of the system of artificial recharge of groundwater resources. Detailed investigations shows, that Steady state HM cannot provide information needed for elaboration of optimal recharge rates and method of controlling them, the transient HM of the Baltezers well fields must be used for those purposes. Artificial recharging of groundwater resources in the Baltezers region does not make risk for groundwater quality to exceed permitted parameters’ values for drinking water, and make substation contribution to protect groundwater quality from possible contamination from new urban territories in NW from the siphon lines in Baltezers region

Natural isotopes support groundwater origin as a driver of mire type and biodiversity in Slitere National Park, Latvia

Slitere National Park in Latvia is home to rich fens with many endangered and threatened plant species. This study aims to address how the hydrological systems affect vegetation biodiversity (cf. Wolejko et al. 2019) in the mire systems of the National Park: the base-rich inter-dune mires and extremely base-rich calcareous fens. Groundwater samples from these areas were collected for measurements of ion composition and natural isotopes of C, H and O. Also, we simulated groundwater flow paths from the highest local topographical point (a nearby sandy plateau) to the sea, and calculated the residence times of these groundwater flows. The results show that the inter-dune mires are supplied by a mixture of local and regional groundwater systems. The groundwater supply at one of the inter-dune mires was dominated by local groundwater flow from adjacent dunes, but we also detected a small input of calcareous water. This dominance of local groundwater may have resulted from the presence of drainage ditches and a small stream that drains into the Baltic Sea. In contrast, the extremely base-rich fens were found to be solely dependent on regional groundwater which is likely to discharge at the plateau foothills due to the presence of fault structures. Thus, the mires in Slitere National Park are not as undisturbed as was previously believed. Drainage may have affected the original hydrological flow paths. Further research on the extent of these changes is recommended to preserve the endangered species and high biodiversity of these fens. Also, in order to trace the origin of groundwater flows, further investigation into the larger landscape beyond the plateau might be required

The biocenotic values of Slitere National Park, Latvia: With special reference to inter-dune mires

Inter-dune wetlands in Europe harbour many Red List species because they are very nutrient-poor ecosystems. Most of these wetlands are geologically very young and no or little peat formation has occurred. In Slitere National Park the numerous inter-dune wetlands are relatively old, up to 4500 years old, and most mire communities are peat forming and they are well preserved. However, the hydrological systems that have conserved the mires are largely unknown. In the present study we analysed 128 vegetation relevees of dune mires in order to assess the variation in ecological mire types. We also carried out several short-time studies to get an insight into the peat development and hydrological conditions that sustain the mires. We describe peat profiles and measured temperature profiles and electrical conductivity in 26 dune valleys. We distinguished three main vegetation units and ten sub-units, representing various stages in peat formation. Based on electrical conductivity and temperature profiles we hypothesised that the mires were sustained by both local and more regional groundwater flows, of which the latter were possibly disturbed by anthropogenic influences, mainly outside the National Park. The importance of the Park was evaluated by comparing it to species lists of wetlands from all countries bordering the Baltic Sea. On the European scale the inter-dune wetlands of Slitere National Park are very important because they represent well-developed examples of mire formation on a landscape scale, which elsewhere in most of Europe are rare or have become extinct due to intensive land use

The peatland map of Europe

Based on the 'European Mires Book' of the International Mire Conservation Group (IMCG), this article provides a composite map of national datasets as the first comprehensive peatland map for the whole of Europe. We also present estimates of the extent of peatlands and mires in each European country individually and for the entire continent. A minimum peat thickness criterion has not been strictly applied, to allow for (often historically determined) country-specific definitions. Our 'peatland' concept includes all 'mires', which are peatlands where peat is being formed. The map was constructed by merging national datasets in GIS while maintaining the mapping scales of the original input data. This 'bottom-up' approach indicates that the overall area of peatland in Europe is 593,727 km(2). Mires were found to cover more than 320,000 km (2) (around 54 % of the total peatland area). If shallow-peat lands (<30 cm peat) in European Russia are also taken into account, the total peatland area in Europe is more than 1,000,000 km(2), which is almost 10 % of the total surface area. Composite inventories of national peatland information, as presented here for Europe, may serve to identify gaps and priority areas for field survey, and help to cross-check and calibrate remote sensing based mapping approaches