Phosphorus in settling matter and bottom sediments in lakes loaded by agriculture

Krogerus, Kirsti; Ekholm, Petri

doi:10.1023/a:1024879309946

Cited by 21 publications

(14 citation statements)

References 33 publications

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“…High DIN:SRP ratios are frequent in other Mediterranean coastal lagoons that receive high levels of freshwater discharge (Lucena et al, 2002). The greatest part of phosphate input to the lagoon might be trapped in lagoon sediments as insoluble phosphate and then liberated in anoxic conditions (Perkins, 1974) or by wind induced resuspension of particulate matter (Krogerus and Ekholm, 2003).…”

Section: Discussionmentioning

confidence: 99%

Nutrient And Particulate Inputs Into The Mar Menor Lagoon (Se Spain) From An Intensive Agricultural Watershed

Velasco

Lloret

Millán

et al. 2006

Water Air Soil Pollut

128

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Abstract. The Mar Menor is a Mediterranean coastal lagoon of high conservation interest, but highly threatened by non-point pollution derived from agricultural lands. This is the first comprehensive study that evaluates the inputs into the Mar Menor from a drainage channel and the Albujón wadi, the main watercourse, and their influence on the trophic state of the lagoon. Discharge variation during the study period was closely related to the precipitation pattern. Suspended sediments and particulate organic matter loads greatly increased with flash floods. Nitrate concentrations, too, increased after heavy autumn rains through washing of the nitrates accumulated in soils, although no significant correlations were found between nitrate concentrations and precipitation or discharge. The nitrate load depended on several factors including the intensity and frequency of precipitation, and the nitrates accumulated in soils as a result of fertilisation. Phosphate concentrations decreased with higher flows. The total input into the lagoon from the two discharges estimated for the period September 2002-October 2003 were 10,142 t.yr −1 of suspended sediments, 389 t.yr −1 of particulate organic matter, 2,010 t.yr −1 of dissolved inorganic nitrogen (93 % as NO − 3 ) and 178 t.yr −1 of soluble reactive phosphorus. The Albujón wadi exported about 80% of the N load and 70% of the P load. Higher flows contributed approximately 80% of the total discharge and nutrient loads, 99% of suspended sediment and 88% of the particulate organic matter. Mean suspended solids and nutrient concentrations in the lagoon followed a spatial pattern, decreasing with distance from the mouth of the Albujón wadi. Water nitrate and phosphate concentrations in the Mar Menor lagoon were lower than reference limits for eutrophic conditions, except after heavy rains. Nutrient concentrations were positively correlated with precipitation variables and particulate and nutrient inputs. Phosphorus was the most limiting nutrient in the Mar Menor, the DIN:SRP ratios found being higher than the Redfield ratio on all sampling dates. Phytoplankton bloom in the lagoon was only found next to the Albujón mouth during late summer and extending 5000 m into the lagoon in autumn as a consequence of large freshwater discharge caused by flash floods. Around 53.6% of the variation in chlorophyll a in the lagoon was explained by the NH 4 and NO 3 inputs and distance from the Albujón mouth. A good deal of P input into the lagoon is retained in the sediments, supporting a high biomass of the benthic macroalga Caulerpa prolifera in spring and summer.

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Section: Discussionmentioning

confidence: 99%

Nutrient And Particulate Inputs Into The Mar Menor Lagoon (Se Spain) From An Intensive Agricultural Watershed

Velasco

Lloret

Millán

et al. 2006

Water Air Soil Pollut

128

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“…Such a phenomenon can only be attributed to internal processes, since the bulk of the nutrient load from agriculture enters the waters outside the productive period. In fact, in some Finnish agricultural lakes the summertime concentration of Tot-P is higher in the lake than in the inflow (Kauppi et al, 1988;Krogerus and Ekholm, 2003). In Danish P-rich lakes (Tot-P in summer >100 μg L −1 ), the summertime Tot-P concentrations have typically been 2-4 times the wintertime values (Søndergaard et al, 1999), mainly due to increased efflux of P from the sediment.…”

Section: General Characteristicsmentioning

confidence: 99%

“…Although numerous studies have focussed on the amount, pathways, mechanisms and reduction of agricultural nutrient losses to aquatic systems (Särkkä, 1972;Kauppi, 1984;Turtola and Paajanen, 1995;Yli-Halla et al, 1995;Vuorenmaa et al, 2002;Koskiaho et al, 2003), relatively little information is available on the actual impact of these losses on lakes in Finland. The response of a specific lake to present and historical loads has been examined by Kukkonen and Tynni (1970), Kauppi et al (1988), Räsänen et al (1992), Salonen et al (1993), Knuuttila et al (1994), Ekholm et al (1997), Itkonen and Olander (1997), Räsänen et al (2004) and Krogerus and Ekholm (2003). However, with the exception of the survey of Kauppi et al (1990a,b) on the relationship between land-use and blue-green algal blooms, no large-scale studies have been conducted on general spatial and temporal trends in the water quality of agricultural lakes.…”

Section: Introductionmentioning

confidence: 99%

Agricultural Lakes in Finland: Current Water Quality and Trends

Ekholm

Mitikka

2006

Environ Monit Assess

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Agriculture is the largest source of nutrients into surface waters in Finland, and yet relatively little is known about the actual impact of the agricultural load on the state of lakes. We analysed the water quality data of 20 Finnish agricultural lakes and found that they had higher levels of nutrients, chlorophyll a and turbidity than did the other types of lakes (e.g. those receiving point-source load) in the national monitoring network (the Finnish Eurowaternet). Currently, six of the agricultural lakes can be classified as eutrophic and 14 as hypertrophic. Trend analysis (based on Kendall's tau-b) indicated that during 1976-2002 the water quality of the lakes either remained constant or showed signs of increasing eutrophication and elevated turbidity. Decreasing nutrient concentrations were found only in one intensively restored lake. In none of the lakes had the chlorophyll a concentration decreased. The results of the trend analysis are compatible with the recent finding that, despite vigorous efforts, the nutrient load from agriculture has not declined in Finland. Recovery of the most eutrophied agricultural lakes would call for a drastic reduction in the external nutrient load, possibly supplemented with in-lake restoration.

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“…These studies 0925-8574/$ -see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ecoleng.2006.06.002 include: (a) the origin and eutrophication of lakes (Scheren et al, 2000;Gulati and van Donk, 2002;Coveney et al, 2002;Xie and Xie, 2002;Krogerus and Ekholm, 2003), and some long-term studies following restoration measures (van Duin et al, 1998;Kleeberg and Kohl, 1999;Coveney et al, 2002); (b) Restoration techniques involving hydrological and chemical manipulation aimed at P reductions in the inflows and in the lake itself, and manipulation of lake biota (biomanipulation) and case studies (Stuben et al, 1998;Xie et al, 2004); (c) Effect of release of sediment nutrients on the water quality and restoration projects (Murphy et al, 2001;Kim et al, 2003;Fytianos and Kotzakioti, 2005), including achievements and failures, and future research directions, and (d) Modelling studies based on both empirical and theoretical information (Rydin, 2000;Tao et al, 2000;Kim et al, 2004;Ruley and Rusch, 2004) and the role of fish, macrophytes and zooplankton in lake restoration (Qiu et al, 2001;Ostroumov, 2004).…”

Section: Introductionmentioning

confidence: 99%

Estimation of the natural purification rate of a eutrophic lake after pollutant removal

Jiang

Shen

2006

Ecological Engineering

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Phosphorus in settling matter and bottom sediments in lakes loaded by agriculture

Cited by 21 publications

References 33 publications

Nutrient And Particulate Inputs Into The Mar Menor Lagoon (Se Spain) From An Intensive Agricultural Watershed

Nutrient And Particulate Inputs Into The Mar Menor Lagoon (Se Spain) From An Intensive Agricultural Watershed

Agricultural Lakes in Finland: Current Water Quality and Trends

Estimation of the natural purification rate of a eutrophic lake after pollutant removal

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