Nutrient pressures and ecological responses to nutrient loading reductions in Danish streams, lakes and coastal waters

Kronvang, Brian; Jeppesen, Erik; Conley, Daniel J.; Søndergaard, Martin; Larsen, Søren E.; Ovesen, Niels Bering; Carstensen, Jacob

doi:10.1016/j.jhydrol.2004.07.035

Cited by 266 publications

(171 citation statements)

References 39 publications

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“…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%

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: 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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“…Today, most western countries have implemented measures to target pointsource related nutrient loadings with a special focus on sewage, and diffuse loading is therefore now of particular importance for the overall nutrient input to freshwater systems in this part of the world (Kronvang et al 2005). For developing countries, however, point sources, especially sewage discharges associated with rural living, remain an excessive source of nutrients entering freshwater ecosystems and they continue to increase in parallel with the growing economy and improvement of rural life quality (Chen et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Assessing ways to combat eutrophication in a Chinese drinking water reservoir using SWAT

Nielsen

Trolle

et al. 2013

Mar. Freshwater Res.

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Abstract. Across China, nutrient losses associated with agricultural production and domestic sewage have triggered eutrophication, and local managers are challenged to comply with drinking water quality requirements. Evidently, the improvement of water quality should be targeted holistically and encompass both point sources and surface activities within the watershed of a reservoir. We expanded the ordinary Soil Water Assessment Tool -(SWAT) with a widely used empirical equation to estimate total phosphorus (TP) concentrations in lakes and reservoirs. Subsequently, we examined the effects of changes in land and livestock management and sewage treatment on nutrient export and derived consequences for water quality in the Chinese subtropical Kaiping (Dashahe) drinking water reservoir (supplying 0.4 million people). The critical load of TP was estimated to 13.5 tonnes yr À1 in order to comply with the minimum drinking water requirements, which corresponds to 87% of the simulated load to the reservoir at present. Both the implementation of buffer zones along rivers and removal of sewage discharges showed marked improvement in reservoir water quality. Future research should focus on both hydrological model performance and nutrient transport pathways, which are challenged by a complex artificially altered water infrastructure in the form of ditches, channels and ponds in monsooninfluenced subtropical watersheds.

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“…Agriculture represents a large sector of Danish economy due to a suitable climate and relatively good soils. Manure is the main fertiliser source for agricultural production (Dalgaard et al, 2011b) and represents more than 80 % of the N source in Danish streams, lakes and coastal waters (Kronvang et al, 2005(Kronvang et al, , 2008National Environmental Research Institute, 2006). We investigated the fractions of dissolved inorganic nitrogen (DIN) and DON within total dissolved nitrogen (TDN) concentrations and fluxes in the stream water, respectively.…”

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confidence: 99%

Spatial distribution of soils determines export of nitrogen and dissolved organic carbon from an intensively managed agricultural landscape

Wohlfart¹,

Exbrayat

Schelde

et al. 2012

Biogeosciences

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Abstract. The surrounding landscape of a stream has crucial impacts on the aquatic environment. This study pictures the hydro-biogeochemical situation of the Tyrebaekken creek catchment in central Jutland, Denmark. The intensively managed agricultural landscape is dominated by rotational croplands. The small catchment mainly consist of sandy soil types besides organic soils along the streams. The aim of the study was to characterise the relative influence of soil type and land use on stream water quality. Nine snapshot sampling campaigns were undertaken during the growing season of 2009. Total dissolved nitrogen (TDN), nitrate (NO − 3 ), ammonium nitrogen and dissolved organic carbon (DOC) concentrations were measured, and dissolved organic nitrogen (DON) was calculated for each grabbed sample. Electrical conductivity, pH and flow velocity were measured during sampling. Statistical analyses showed significant differences between the northern, southern and converged stream parts, especially for NO − 3 concentrations with average values between 1.4 mg N l −1 and 9.6 mg N l −1 . Furthermore, throughout the sampling period DON concentrations increased to 2.8 mg N l −1 in the northern stream contributing up to 81 % to TDN. Multiple-linear regression analyses performed between chemical data and landscape characteristics showed a significant negative influence of organic soils on instream N concentrations and corresponding losses in spite of their overall minor share of the agricultural land (12.9 %). On the other hand, organic soil frequency was positively correlated to the corresponding DOC concentrations. Croplands also had a significant influence but with weaker correlations. For our case study we conclude that the fractions of coarse textured and organic soils have a major influence on N and DOC export in this intensively used landscape. Meanwhile, the contribution of DON to the total N losses was substantial.

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Nutrient pressures and ecological responses to nutrient loading reductions in Danish streams, lakes and coastal waters

Cited by 266 publications

References 39 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

Assessing ways to combat eutrophication in a Chinese drinking water reservoir using SWAT

Spatial distribution of soils determines export of nitrogen and dissolved organic carbon from an intensively managed agricultural landscape

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