Trends in nutrient concentrations in Latvian rivers and the response to the dramatic change in agriculture

Stålnacke, Per; Grimvall, Anders; Libiseller, Claudia; Laznik, M.; Kokorìte, Ilga

doi:10.1016/s0022-1694(03)00266-x

Cited by 142 publications

(127 citation statements)

References 51 publications

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“…The use of fertilizer and livestock densities decreased dramatically following the economic breakdown in 1990 (Figs. 4a and b;Löfgren et al, 1999;Stålnacke et al, 2003;Vagstad et al, 2004;Eriksson et al, 2007). However, the overall nutrient load to the Baltic Sea has not changed significantly during the last 30 years (Fig.…”

Section: Past and Possible Future Changes In N And P Fluxesmentioning

confidence: 91%

“…However, the overall nutrient load to the Baltic Sea has not changed significantly during the last 30 years (Fig. 5;HELCOM, 2004, and references therein; Stålnacke et al, 1999b) although recently decreasing trends in N and P concentrations of several minor rivers have been reported (Iital et al, 2005;Kronvang et al, 2005). Interestingly, rivers draining countries with a large N-surplus -that is all N added to a hectare sown area such as fertilizer and manure, atmospheric deposition and agricultural imports as feed minus all outputs such as agricultural export and human consumption (Löfgren et al, 1999;Campling et al, 2005) -actually showed decreasing TN and TP river concentrations after the collapse of the agricultural sector.…”

Section: Past and Possible Future Changes In N And P Fluxesmentioning

confidence: 99%

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Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives

Humborg

Mörth

Sundbom

et al. 2007

Hydrol. Earth Syst. Sci.

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Abstract. The paper reviews critical processes for the landsea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage treatment, agricultural practices and increased hydropower demand (for N, P and Si) and of global warming, i.e., changes in hydrological patterns (for C). These most significant drivers will not only change the total amount of nutrient inputs and fluxes of organic and inorganic forms of carbon to the Baltic Sea, their ratio (C:N:P:Si) will alter as well with consequences for phytoplankton species composition in the Baltic Sea. In summary, we propose that N fluxes may increase due to higher livestock densities in those countries recently acceded to the EU, whereas P and Si fluxes may decrease due to an improved sewage treatment in these new EU member states and with further damming and still eutrophic states of many lakes in the entire Baltic Sea catchment. This might eventually decrease cyanobacteria blooms in the Baltic but increase the potential for other nuisance blooms. Dinoflagellates could eventually substitute diatoms that even today grow below their optimal growth conditions due to low Si concentrations in some regions of the Baltic Sea. C fluxes will probably increase from the boreal part of the Baltic Sea catchment due to the expected higher temperatures and heavier rainfall. However, it is not clear whether dissolved organic carbon and alkalinity, which have opposite feedbacks to global warming, will increase in similar amounts, because the spring flow peak will be smoothed out in time due to higher temperatures that cause less snow cover and deeper soil infiltration.

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Section: Past and Possible Future Changes In N And P Fluxesmentioning

confidence: 91%

Section: Past and Possible Future Changes In N And P Fluxesmentioning

confidence: 99%

Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives

Humborg

Mörth

Sundbom

et al. 2007

Hydrol. Earth Syst. Sci.

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“…The impact of instream physical and biological processes on regulation of P fluxes through river systems is still poorly understood (Stålnacke et al 2003). Sorption onto bottom sediments and to a lesser extent uptake by aquatic plants is the main causes of retention (Hill 1981).…”

Section: Background: Leaching and Transport Of Phosphorusmentioning

confidence: 99%

Process Based Modelling of Phosphorus Losses from Arable Land

Ekstrand

Wallenberg

Djodjic

2010

AMBIO

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Improved understanding of temporal and spatial Phosphorus (P) discharge variations is needed for improved modelling and prioritisation of abatement strategies that take into account local conditions . This study is aimed at developing modelling of agricultural Phosphorus losses with improved spatial and temporal resolution, and to compare the accuracy of a detailed process-based model with a rainfall-runoff coefficient-based model. The process-based SWAT model (Soil and Water Assessment Tool) was implemented for five river basins in central Sweden, and results compared with the rainfall-runoff coefficient-based model WATSHMAN (Watershed Management System) for one of these river basins. Parameter settings and attribute values were adapted to Scandinavian soil conditions, crops and management practices. Model performance regarding flow dynamics was overall satisfactory. Comparable results were achieved at several scales. The modelled P load was of high accuracy for the days when monitoring data were available for validation, generally once a month. Modelled monthly P load did not fit as well with averaged monthly monitoring load values, mainly since monthly monitoring often partly or entirely misses the peak flows. The comparison of SWAT and WATSHMAN gave slightly better results for the processbased model (SWAT). Better spatial resolution for input data such as Soil-P content and agricultural management practices will be required to reach modelling results that enable identification of measures adapted to local conditions.

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“…For the Baltic outflow into the North Sea more information on time-dependent nutrient loads have become available, because of the intensive work on the eutrophication of the Baltic Sea (Wulff et al 2001). Stalnacke et al (2003) presented time series of river loads for rivers discharging into the Bay of Riga (Baltic Sea) for the period 1987-1998, which reflect the drastic reduction of fertilizers in the Baltic states Estonia, Latvia, and Lithuania. All of these time series of river loads are important building blocks for establishing time-dependent budgets of nutrients in the continental coastal zone.…”

Section: Riverine Inputs In Relation To Other Budget Contributions Tomentioning

confidence: 99%

Variability of continental riverine freshwater and nutrient inputs into the North Sea for the years 1977–2000 and its consequences for the assessment of eutrophication

Radach¹,

Pätsch²

2007

Estuaries and Coasts

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We determined the monthly and annual riverine freshwater, nitrogen (N) and phosphorus (P) loading into the North Sea from Belgium, The Netherlands, and Germany for the years 1977-2000. An average of 133 km 3 yr 21 of the 309 km 3 yr 21 precipitation into the watershed is carried by the rivers into the sea. Total freshwater discharge fluctuates with a strong 6-7 yr periodicity, is strongly correlated with precipitation, and exhibits a slight long-term decrease. The temporal changes of regional patterns of precipitation lead to changing ratios of annual discharge of the western rivers compared to the eastern rivers, varying between 2.2 and 3.5. The long-term oscillations in discharge were more pronounced as discharge increased. The annual means of total and dissolved inorganic N and P loads were estimated to be 722 and 582 kt N yr 21 and 48 and 26 kt P yr 21 , respectively. The monthly N loads were much more strongly correlated with discharge, compared to the monthly P loads. Total N and P as well as dissolved inorganic N also demonstrated a 6-7 yr periodicity. The annual N loads decreased by about 17 kt N yr 21 from 1977 to 2000. The total phosphorus and phosphate loads decreased from about 80 and 50 kt P yr 21 in the 1980s to 25 and 12 kt P yr 21 , respectively, in the 1990s. The western rivers contributed the major part of the nutrient loads. The long-term oscillations in their nutrient loads were much more pronounced, compared to the eastern rivers. The area-specific loading rates estimated for all rivers are comparable to earlier estimates using shorter data records, smaller sample sizes, and a less complete watershed monitoring program. The monthly and annual average N:P ratios and their variability increased considerably for individual rivers during the study interval. These results confirm that the water quality of European continental rivers is strongly influenced by intense land use. They demonstrate the necessity for using long time series monitoring results to assess change and evaluate the effects of climate change on the North Sea coastal ecosystems, using ecosystem models on decadal time scales.

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Trends in nutrient concentrations in Latvian rivers and the response to the dramatic change in agriculture

Cited by 142 publications

References 51 publications

Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives

Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives

Process Based Modelling of Phosphorus Losses from Arable Land

Variability of continental riverine freshwater and nutrient inputs into the North Sea for the years 1977–2000 and its consequences for the assessment of eutrophication

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