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Gunnars, Anneli; Blomqvist, Sven

doi:10.1023/a:1005744610602

Cited by 150 publications

(28 citation statements)

References 71 publications

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“…The implications of this relationship are central to understanding sediment P cycling in shallow bays because the redox state of the environment can significantly affect Fe and Mn oxide minerals that are important reservoirs of sorbed P (Gunnars and Blomquist 1997;Roden and Edmonds 1997;Petticrew and Arocena 2001).…”

Section: Discussionmentioning

confidence: 99%

Relating sediment phosphorus mobility to seasonal and diel redox fluctuations at the sediment–water interface in a eutrophic freshwater lake

Smith

Watzin

Druschel

2011

Limnology & Oceanography

122

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Relationships between phosphorus cycling and redox conditions in the sediments of eutrophic Missisquoi Bay, Lake Champlain were investigated over diel and seasonal timescales in three consecutive summers (2007)(2008)(2009), one of which (2007) did not experience a cyanobacteria bloom for the first time in a decade. Sediment extraction data showed that reactive phosphorus (RP) is strongly correlated to reactive iron (RFe), suggesting that the mobility of a large portion (30-40%) of the total sediment phosphorus pool is associated with nanocrystalline iron oxide minerals that may be influenced by redox conditions. RP concentrations in the top sediments increased throughout 2007 but decreased throughout 2008; calculations indicate that , 1 mm of sediment could account for the increased total dissolved phosphorus observed in overlying water. Redox conditions were measured over 24 h in situ within sediment cores and at the sediment-water interface (SWI) at different stages of each season using voltammetry. SWI redox conditions became progressively more reduced across the season and overnight and were significantly more reducing in the presence of a bloom. Soluble RP and cyanobacteria cell counts measured at five depths through the water column strongly correlated with the most reducing conditions at the SWI. Observations suggest that redox controlled nutrient flux between the sediments and the water column is variable over diel and seasonal cycles. Cyanobacteria blooms most significantly affect SWI redox conditions, suggesting that blooms may enhance RP flux from sediments, setting up a positive feedback loop that can propagate and sustain blooms in shallow freshwater systems.

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Section: Discussionmentioning

confidence: 99%

Relating sediment phosphorus mobility to seasonal and diel redox fluctuations at the sediment–water interface in a eutrophic freshwater lake

Smith

Watzin

Druschel

2011

Limnology & Oceanography

122

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“…Moreover, these methods do not quantify the settling fluxes of P to the sediment and thus are not sufficient to determine whether the sediment is a net P sink or source (Nielsen et al, 2001;Hupfer and Lewandowski, 2008). Unfortunately, direct sedimentation measurements are prone to large uncertainties (Blomqvist and Larsson, 1994;Gustafsson et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

A Baltic Sea estuary as a phosphorus source and sink after drastic load reduction: seasonal and long-term mass balances for the Stockholm inner archipelago for 1968–2015

et al. 2018

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Abstract. Internal phosphorus (P) loading from sediments, controlled by hypoxia, is often assumed to hamper the recovery of lakes and coastal areas from eutrophication. In the early 1970s, the external P load to the inner archipelago of Stockholm, Sweden (Baltic Sea), was drastically reduced by improved sewage treatment, but the internal P loading and its controlling factors have been poorly quantified. We use two slightly different four-layer box models to calculate the area's seasonal and annual P balance (input-export) and the internal P exchange with sediments in 1968-2015. For 10-20 years after the main P load reduction, there was a negative P balance, small in comparison to the external load, and probably due to release from legacy sediment P storage. Later, the stabilized, near-neutral P balance indicates no remaining internal loading from legacy P, but P retention is low, despite improved oxygen conditions. Seasonally, sediments are a P sink in spring and a P source in summer and autumn. Most of the deep-water P release from sediments in summer-autumn appears to be derived from the settled spring bloom and is exported to outer areas during winter. Oxygen consumption and P release in the deep water are generally tightly coupled, indicating limited iron control of P release. However, enhanced P release in years of deep-water hypoxia suggests some contribution from redox-sensitive P pools. Increasing deep-water temperatures that stimulate oxygen consumption rates in early summer have counteracted the effect of lowered organic matter sedimentation on oxygen concentrations. Since the P turnover time is short and legacy P small, measures to bind P in Stockholm inner archipelago sediments would primarily accumulate recent P inputs, imported from the Baltic Sea and from Lake Mälaren.

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“…This capability has been used to support the argument that P will ultimately be the limiting nutrient, since N 2 fixation represents an avenue for helping satisfy N requirements under these circumstances (Doremus 1982;Tyrell 1999). Moreover, inorganic and organic forms of N are often more soluble and hence more available than P (Gunnars and Blomqvist 1997;Wetzel 2001), potentially exacerbating P limitation. Indeed, there are numerous examples of freshwater ecosystems in which P input controls have effectively controlled primary production and successfully arrested the unwanted symptoms of eutrophication (Likens 1972;Smith 1990Smith , 2003.…”

Section: Introductionmentioning

confidence: 99%

Controlling Eutrophication along the Freshwater–Marine Continuum: Dual Nutrient (N and P) Reductions are Essential

Paerl

2009

Estuaries and Coasts

450

272

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Expanding human activities along the freshwater to marine continuum of coastal watersheds increasingly impact nutrient inputs, nutrient limitation of primary production, and efforts to reduce nutrient over-enrichment and eutrophication. Historically, phosphorus (P) has been the priority nutrient controlling upstream freshwater productivity, whereas nitrogen (N) limitation has characterized coastal waters. However, changing anthropogenic activities have caused imbalances in N and P loading, making it difficult to control eutrophication by reducing only one nutrient. Furthermore, upstream nutrient reduction controls can impact downstream nutrient limitation characteristics. Recently, it was suggested that only reducing P will effectively control eutrophication in both freshwater and coastal ecosystems. However, controls on production and nutrient cycling in estuarine and coastal systems are physically and chemically distinct from those in freshwater counterparts, and upstream nutrient management actions (exclusive P controls) have exacerbated N-limited downstream eutrophication. Controls on both nutrients are needed for long-term management of eutrophication along the continuum.

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Untitled

Cited by 150 publications

References 71 publications

Relating sediment phosphorus mobility to seasonal and diel redox fluctuations at the sediment–water interface in a eutrophic freshwater lake

Relating sediment phosphorus mobility to seasonal and diel redox fluctuations at the sediment–water interface in a eutrophic freshwater lake

A Baltic Sea estuary as a phosphorus source and sink after drastic load reduction: seasonal and long-term mass balances for the Stockholm inner archipelago for 1968–2015

Controlling Eutrophication along the Freshwater–Marine Continuum: Dual Nutrient (N and P) Reductions are Essential

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