Aquatic effects of peat extraction and peatland forest drainage: a comparative sediment study of two adjacent lakes in Central Finland

The aquatic effects of forestry practices and peat extraction continue to cause serious concerns. The effect mechanisms of peat extraction on water quality and aquatic ecology of the receiving surface waters are well known, but the impacts are often difficult to differentiate from those of forest management. A pairwise temporal sediment study was conducted on two adjacent lakes in Central Finland to study whether the unique effects of peat extraction can be detected in an area of intensive forest drainage. Both lakes are affected by forestry, but the reference lake has no history of peat extraction in its watershed. The deepest parts of the lakes were cored through the lacustrine sediments,…

Accuracy of 210Pb dating in two annually laminated lake sediments with high Cs background

Abstract A low-background gamma ray spectroscopy system has been used for nondestructive determination of 210Pb, 226Ra, 134Cs and 137Cs in lake sediment samples. Two Finnish sediment cores with high 137Cs activity originating from the Chernobyl accident have been analysed and dated using 210Pb. The accuracy of the 210Pb dating method was checked by varve counting of replicate samples. In one lake the 210Pb method gave similar dating results as varves, but in the other lake significant differences were detected. It was found that a high Cs concentration significantly impairs the accuracy of the 210Pb activity measurement. However, tha reliability of the dating result depends mostly on the co…

Benthic Invertebrates in Relation to Acidity in Finnish Forest Lakes

In order to examine the effects of acidity on abundance and community structure of the benthic invertebrates in forest lakes and to evaluate the applicability of certain benthic animals as early warning indicators of lake acidification, 140 lakes, situated mainly in southern Finland, were studied by quantitative and qualitative sampling methods.

Recent environmental history of a large, originally oligotrophic lake in Finland: a palaeolimnological study of chironomid remains

The sedimentary chironomid stratigraphy in short-core samples covering approx. the past 150 years was studied in the northernmost basin of Lake Paijanne, southern Finland (62° 11′ N, 25° 48′ E). The basin has received effluent loading from the wood-processing industry and municipal waste water. Four developmental stages were distinguished based on the changes in chironomid assemblages: 1. Pre-industrial stage (dated by the210Pb method as covering approximately the period 1838–1936), 2. Stage of increasing pollution (approx. 1944–1973), 3. The ‘black decade’, or the period of worst pollution (approx. 1973–1983), and 4. Water protection stage (approx. 1983 onwards). During the first stage the…

Pohjan liejukerrostumat kertovat Jyväsjärven ympäristöhistorian

Jyväsjärven ympäristöhistoriaa ja ekologisen tilan muuttumista 1700-luvulta nykypäiviin selvitettiin eliöjäänteiden ja sedimentin fysikaalisten ja kemiallisten ominaisuuksien perusteella. Liejunäytteistä tutkittiin 32 alkuaineen ja orgaanisten haitta-aineiden, kuten hartsihappojen, PCB:n, DDT:n ja sen hajoamistuotteiden esiintymistä sekä piilevien ja surviaissääsken toukkien jäänteitä. Tämän ajanjakson, runsaan kahden vuosisadan aikana Jyväsjärvi muuttui erämaajärvestä kaupunkijärveksi. Tämä jakso sisältyy Jyväsjärvessä noin 80 cm:n paksuiseen liejukerrokseen. Yhden vuoden tapahtumat mahtuvat tässä liejuisessa historiankirjassa sivuun, jonka paksuus vaihtelee esiteollisen ajan noin kahdesta…

The relevance of ecological status to ecosystem functions and services in a large boreal lake

Summary Environmental conventions aim to protect ecosystem structures and functions to provide goods and services for mankind. The degree of aquatic ecosystem naturalness, or ecological status as it is defined in the Water Framework Directive (WFD) of the European Union, is notionally linked to supplies of ecosystem services. In practice, these links have rarely been documented or even investigated, and to justify conservation and management objectives based on the status indicators, it is essential to demonstrate their relationships to ecosystem functions and services. The WFD requires member states to classify their surface waters aiming to achieve good ecological status of water bodies. …

Contrasting Patterns in Chironomid (Chironomidae) Communities of Shallow and Deep Boreal Lakes Since the 1960s

Chironomids have been widely used as indicators of trophic conditions of lakes due to their species-specific environmental requirements. In order to understand resilience and deterioration of aquatic ecosystems due to increases and/or decreases in external loading, recent chironomid community and water chemistry data of seven southern Finnish lakes with varying anthropogenic pressures and bathymetric properties were compared with similar data from the 1960s. Altogether 64 taxa were found. At present, the most numerous taxa are Procladius spp., Chironomus f.l. plumosus, Chironomus f.l. salinarius, Stictochironomus f.l. psammophilus, Benthalia spp., Tanytarsus spp. and Cladotanytarsus. In fou…

Sample size in the monitoring of benthic macrofauna in the profundal of lakes: evaluation of the precision of estimates

We discuss here the influence of sample size (number of replicates) on the accuracy and precision of the results when sampling profundal benthos with an Ekman grab according to the Finnish standard, SFS 5076, which is equivalent to the Swedish and Norwegian standards. The aim was to find criteria for choosing a sample size which would avoid any powerful influence of chance on the results without entailing an unreasonable amount of work for monitoring purposes.

Environmental history of an urban lake: a palaeolimnological study of Lake Jyväsjärvi, Finland

Sedimentary diatom frustules and chironomid remains, in addition to the chemical stratigraphy of 32 elements and organic pollutants such as resin acids, PCB, DDT and its metabolites, were studied from core samples taken from Lake Jyvasjarvi in Central Finland (64° 14′ N, 25° 47′ E). The sediment profile covered over 200 years, with the oldest samples representing a period of very low human interference. The town of Jyvaskyla was established on the lake shore in 1837, and the lake received untreated municipal wastewater from the town up until, 1977. A paper mill started operations in 1872 and began discharging effluent into Lake Jyvasjarvi. In recent years this effluent loading has been redu…

Long-term dynamics of water-borne nitrogen, phosphorus and suspended solids in the lower Don River basin (Russian Federation)

A long-term study (1986–2002) of water-borne nutrient and suspended solids dynamics was undertaken on the lower Don River, which plays an extremely important role in the water supply of the Black Sea and Azov Sea basin. Suspended solids were greatest in spring and summer and were correlated to river discharge. Mean annual nitrogen concentrations increased from 1986 to 1995 and then decreased from 1996 to 2002. Unlike nitrogen, phosphorus concentrations (both phosphates and total phosphorus) gradually increased throughout the study period changing the river from an oligotrophic to upper mesotrophic status. If this trend continues phytoplankton could become nitrogen-limited leading to the dev…

Successive alkalinity producing system for the treatment of acid sulphate soil runoff: preliminary results of a field trial

A successive alkalinity producing system (SAPS) has been investigated as a potential passive treatment option for acid, metal containing runoff from acid sulphate soil. A pilot-scale system was installed at an agricultural land site in Rintala embankment area in mid-western Finland. The experimental layout consists of three parallel treatment units: two different SAPS cells and one limestone-filled cell for comparison of performance. The SAPS cells are composed of a bottom layer of limestone and a top layer of compost supplemented with sand. One of the SAPS cells contains sulphate-rich, waste gypsum mixed with the compost layer in order to enhance the metal reduction by sulphate reducing-ba…

Okavirsut ja voimatölkki : julkaisemattoman tiedon lähteillä

Data from: The relevance of ecological status to ecosystem functions and services in a large boreal lake

1. Environmental conventions aim to protect ecosystem structures and functions to provide goods and services for mankind. The degree of aquatic ecosystem naturalness, or ecological status as it is defined in the Water Framework Directive (WFD) of the European Union, is notionally linked to supplies of ecosystem services. In practice these links have rarely been documented or even investigated and, to justify conservation and management objectives based on the status indicators, it is essential to demonstrate their relationships to ecosystem functions and services. 2. The WFD requires member states to classify their surface waters aiming to achieve good ecological status of water bodies. How…