Biogeochemical nutrient cycles and nutrient management strategies

Conley, Daniel J.

doi:10.1007/978-94-017-2163-9_10

Cited by 173 publications

(175 citation statements)

References 37 publications

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“…Inputs of organic matter, nitrogen and phosphorus to coastal ecosystems have increased greatly (Nixon 1995;Howarth et al 1996;Conley 2000;Stedmon et al 2006;Sharp 2010). Although eutrophication is the major concern related to these inputs, the pH of coastal waters is also influenced through the enhanced CO 2 uptake from primary production and CO 2 release from respiration associated with increased nutrient inputs.…”

Section: Impacts Of Anthropogenic Watershed Perturbations On Seawater Phmentioning

confidence: 99%

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Duarte

Hendriks

Moore

et al. 2013

Estuaries and Coasts

612

452

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Ocean acidification due to anthropogenic CO 2 emissions is a dominant driver of long-term changes in pH in the open ocean, raising concern for the future of calcifying organisms, many of which are present in coastal habitats. However, changes in pH in coastal ecosystems result from a multitude of drivers, including impacts from watershed processes, nutrient inputs, and changes in ecosystem structure and metabolism. Interaction between ocean acidification due to anthropogenic CO 2 emissions and the dynamic regional to local drivers of coastal ecosystems have resulted in complex regulation of pH in coastal waters. Changes in the watershed can, for example, lead to changes in alkalinity and CO 2 fluxes that, together with metabolic processes and oceanic dynamics, yield high-magnitude decadal changes of up to 0.5 units in coastal pH. Metabolism results in strong diel to seasonal fluctuations in pH, with characteristic ranges of 0.3 pH units, with metabolically intense habitats exceeding this range on a daily basis. The intense variability and multiple, complex controls on pH implies that the concept of ocean acidification due to anthropogenic CO 2 emissions cannot be transposed to coastal ecosystems directly. Furthermore, in coastal ecosystems, the detection of trends towards acidification is not trivial and the attribution of these changes to anthropogenic CO 2 emissions is even more problematic. Coastal ecosystems may show acidification or basification, depending on the balance between the invasion of coastal waters by anthropogenic CO 2 , watershed export of alkalinity, organic matter and CO 2 , and changes in the balance between primary production, respiration and calcification rates in response to changes in nutrient inputs and losses of ecosystem components. Hence, we contend that ocean acidification from anthropogenic CO 2 is largely an open-ocean syndrome and that a concept of anthropogenic impacts on marine pH, which is applicable across the entire ocean, from coastal to open-ocean environments, provides a superior framework to consider the multiple components of the anthropogenic perturbation of marine pH trajectories. The concept of anthropogenic impacts on seawater pH acknowledges that a regional focus is necessary to predict future trajectories in the pH of coastal waters and points at opportunities to manage these trajectories locally to conserve coastal organisms vulnerable to ocean acidification.

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Section: Impacts Of Anthropogenic Watershed Perturbations On Seawater Phmentioning

confidence: 99%

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Duarte

Hendriks

Moore

et al. 2013

Estuaries and Coasts

612

452

View full text Add to dashboard Cite

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“…Despite concern over recent eutrophication, the increase in nutrients between pristine conditions and the end of the 19th century may actually have been larger (Conley 2000). Billen et al (1999) estimated the potential pollution load to the river Seine at the turn of the 19th century.…”

Section: Eutrophication Histories In Roskilde Fjord and Laajalahtimentioning

confidence: 99%

Long‐term trends in eutrophication and nutrients in the coastal zone

Clarke

Weckström

Conley

et al. 2006

Limnology & Oceanography

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We used high‐resolution paleoecological records of environmental change to study the rate and magnitude of eutrophication over the last century in two contrasting coastal ecosystems. A multiproxy approach using geochemical and biological indicators and diatom‐based transfer functions provides a long‐term perspective on changes in nutrient concentrations and the corresponding biological and sedimentary responses. In Roskilde Fjord, Denmark, total nitrogen (TN) increased 85% during the last century, with the most rapid increase occurring after the 1950s, corresponding to the postwar increase in N fertilizer use. In Laajalahti Bay, an urban embayment near Helsinki, Finland, total dissolved nitrogen (TDN) increased with growing wastewater inputs and decreased with the remedial actions taken to reduce these discharges. These changes are small relative to the order of magnitude increases in nutrient loading that have occurred in northwestern Europe, where the dissolved inorganic nitrogen (DIN) load has increased more than threefold in certain areas.

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“…This increase in aquatic N has resulted from the doubling of terrestrial N inputs from a mixture of fertilizer production, cultivation of N-fixing crops, and combustion of fossil fuels [6,7]. Likewise, P levels have increased because P-rich rock deposits have been mined to produce fertilizer and detergents which are transported with runoff and wastewater inputs [5,8,9]. In the United States, nearly two-thirds of coastal rivers and estuaries have been significantly impacted by excess nutrients [10,11].…”

Section: Introductionmentioning

confidence: 99%

Nutrient Retention in Restored Streams and Rivers: A Global Review and Synthesis

Johnson

Kaushal

Mayer

et al. 2016

Water

126

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Excess nitrogen (N) and phosphorus (P) from human activities have contributed to degradation of coastal waters globally. A growing body of work suggests that hydrologically restoring streams and rivers in agricultural and urban watersheds has potential to increase N and P retention, but rates and mechanisms have not yet been analyzed and compared across studies. We conducted a review of nutrient retention within hydrologically reconnected streams and rivers, including 79 studies. We developed a typology characterizing different forms of stream and river restoration, and we also analyzed nutrient retention across this typology. The studies we reviewed used a variety of methods to analyze nutrient cycling. We performed a further intensive meta-analysis on nutrient spiraling studies because this method was the most consistent and comparable between studies. A meta-analysis of 240 experimental additions of ammonium (NH 4 + ), nitrate (NO 3´) , and soluble reactive phosphorus (SRP) was synthesized from 15 nutrient spiraling studies. Our results showed statistically significant relationships between nutrient uptake in restored streams and specific watershed attributes. Nitrate uptake metrics were significantly related to watershed surface area, impervious surface cover, and average reach width (p < 0.05). Ammonium uptake metrics were significantly related to discharge, velocity, and transient storage (p < 0.05). SRP uptake metrics were significantly related to watershed area, discharge, SRP concentrations, and chl a concentrations (p < 0.05). Given that most studies were conducted during baseflow, more research is necessary to characterize nutrient uptake during high flow. Furthermore, long-term studies are needed to understand changes in nutrient dynamics as projects evolve over time. Overall analysis suggests the size of the stream restoration (surface area), hydrologic connectivity, and hydrologic residence time are key drivers influencing nutrient retention at broader watershed scales and along the urban watershed continuum.

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Biogeochemical nutrient cycles and nutrient management strategies

Cited by 173 publications

References 37 publications

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Long‐term trends in eutrophication and nutrients in the coastal zone

Nutrient Retention in Restored Streams and Rivers: A Global Review and Synthesis

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