Arvydas Povilaitis

Factors affecting seasonal and spatial patterns of water quality in Lithuanian rivers

Abstract In this study the main processes influencing water quality of the Lithuanian rivers have been identified. Factor analysis was tested on river hydrochemical data from 108 sites for the period of 1999–2004. It enabled the identification of main factors determining water quality each season. As a result, monitoring stations were grouped into clusters each representing the influence of relevant factor. The tested multivariate statistical procedures can be applied in practice when the reasons for water quality impairments are to be investigated. The findings reveal that Wastewater factor is prominent in small rivers downstream larger towns; Agro-geological factor – in Northern Lithuanias rivers of heavy carbonated soils and intensive agriculture lands as well as in South eastern Lithuanias rivers of more acidic soils; Hardly degradable organics factor – in Northern and Middle Lithuanias rivers of heavy-textured and fertile agricultural soils. The photosynthesis-vegetation and Aeration factors are p...

Agricultural drainage in Lithuania: a review of practices and environmental effects

In Lithuania, artificial drainage is a common agricultural practice. The country remains one of the most extensively drained in the world. The total drained land area occupies 47% of the countrys land area and 86% of the agricultural land area, of which 87% is tile-drained. Although the introduction of drainage has improved the quality of agricultural land, the benefits of drainage are associated with many changes in the local environment. Therefore, a review is presented of the results from various investigations and research studies conducted in Lithuania which have reported the historical and economic aspects of the development of agricultural drainage as well as its environmental effects on landscape structure, local hydrology and nutrient losses in the soil. Temporal changes in drainage run-off since the 1970s are also discussed. Furthermore, positive bidirectional effects of natural processes in and around open drain ditches on both environment and practice are highlighted which show the possibility of fostering them intentionally.

Temporal trends in phosphorus concentrations and losses from agricultural catchments in the Nordic and Baltic countries

This paper in a uniform manner examines temporal trends in phosphorus (P) concentrations and losses from small and well-monitored agricultural catchments in the Nordic and Baltic countries. Thirty-four catchments (range 0.1–33 km2) in Norway (8), Denmark (5), Sweden (8), Finland (4), Estonia (3), Latvia (3) and Lithuania (3) were selected for the study. The time series ranged from 10 (2002–2011) to 21 years (1989–2009). The monthly P concentration and loss time series were tested for significant monotone trends (p < 0.05; two-sided test) using the partial Mann–Kendall test with stream discharge as an explanatory variable. The results show a large variation in concentrations and losses of total phosphorus (TP) among the 34 studied catchments, where the long-term mean annual losses varied from 0.09 to 7.5 kg TP ha−1. In addition, a large interannual variability in losses within catchments was found with up to a factor of 23 between years within the same catchment. Six catchments showed downward temporal trends in the TP loss time series. One upward trend in TP losses was detected in a catchment in south-west Sweden. Eight downward trends were detected in the TP concentration time series. Overall, our results show (1) a huge variability in mean P losses and concentrations among catchments, (2) a huge temporal variability in losses within catchments and (3) few detectable changes in P losses and concentrations over the study period. The results showcase the need for implementation of mitigation strategies towards reduced P losses from agricultural landscapes in the Nordic/Baltic Sea region in order to improve P water quality and ecology in surface waters.