Current Browning of Surface Waters Will Be Further Promoted by Wetter Climate

Wit, Heleen de; Valinia, Salar; Weyhenmeyer, Gesa A.; Futter, Martyn N.; Kortelainen, Pirkko; Austnes, Kari; Hessen, Dag O.; Räike, Antti; Laudon, Hjalmar; Vuorenmaa, Jussi

doi:10.1021/acs.estlett.6b00396

Cited by 280 publications

(219 citation statements)

References 46 publications

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“…Compared to the average values in Table 1, the concentrations have increased by 7%-15%. This is in agreement with a recent study covering the same geographical area, where a trend of 1%-2% annual increase for organic carbon concentrations during a time period of 1990-2013 was calculated and partially attributed to an increase of annual rainfall [16]. However, the MAR processes have not been changed even though the quality of the raw water has changed.…”

Section: Comparison Of the Raw Water Sources And Mar Processessupporting

confidence: 92%

Raw Water Quality and Pretreatment in Managed Aquifer Recharge for Drinking Water Production in Finland

Jokela¹,

Eskola

Heinonen³

et al. 2017

Water

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Abstract:The main objective of managed aquifer recharge (MAR) in Finland is the removal of natural organic matter (NOM) from surface waters. A typical MAR procedure consists of the infiltration of surface water into a Quaternary glaciofluvial esker with subsequent withdrawal of the MAR treated water from wells a few hundred meters downstream. The infiltrated water should have a residence time of at least approximately one month before withdrawal to provide sufficient time for the subsurface processes needed to break down or remove humic substances. Most of the Finnish MAR plants do not have pretreatment and raw water is infiltrated directly into the soil. The objectives of this paper are to present MAR experiences and to discuss the need for and choice of pretreatment. Data from basin, sprinkling, and well infiltration processes are presented. Total organic carbon (TOC) concentrations of the raw waters presented here varied from 6.5 to 11 mg/L and after MAR the TOC concentrations of the abstracted waters were approximately 2 mg/L. The overall reduction of organic matter in the treatment (with or without pretreatment) was 70%-85%. Mechanical pretreatment can be used for clogging prevention. Turbidity of the Finnish lakes used as raw water does not necessitate pretreatment in basin and sprinkling infiltration, however, pretreatment in well infiltration needs to be judged separately. River waters may have high turbidity requiring pretreatment. Biodegradation of NOM in the saturated groundwater zone consumes dissolved oxygen. Thus, a high NOM concentration may create conditions for dissolution of iron and manganese from the soil. These conditions may be avoided by the addition of chemical pretreatment. Raw waters with TOC content up to at least approximately 8 mg/L were infiltrated without any considerations of chemical pretreatment, which should be evaluated based on local conditions.

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Section: Comparison Of the Raw Water Sources And Mar Processessupporting

confidence: 92%

Raw Water Quality and Pretreatment in Managed Aquifer Recharge for Drinking Water Production in Finland

Jokela¹,

Eskola

Heinonen³

et al. 2017

Water

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“…Increased temperatures have been shown to increase soil DOM concentrations, and depending on hydrologic conditions, can lead to increased organic matter runoff to nearby inland waters (Freeman et al 2001;Nguyen and Choi 2015). Moreover, increased precipitation, especially extreme events, is often linked to the brownification and eutrophication of lakes (Williamson et al 2015;de Wit et al 2016;Carpenter et al 2018). In the present study, for example, the brownification of blue lakes in the northeastern U.S. may be facilitated by longer-term regional changes in climate; a 27% increase in precipitation and > 1.5 C increase in annual temperature has been observed here since 1901 (U.S. GCRP 2017).…”

Section: Number Of Lakesmentioning

confidence: 99%

Fewer blue lakes and more murky lakes across the continental U.S.: Implications for planktonic food webs

Leech

Pollard

Labou

et al. 2018

Limnology & Oceanography

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Elevated allochthonous inputs of organic matter are increasingly recognized as a driver of ecosystem change in lakes, particularly when concurrent with eutrophication. Evaluation of lakes in a nutrient-color paradigm (i.e., based on total phosphorus and true color) enables a more robust approach to research and management. To assess temporal and spatial patterns in nutrient-color status for U.S. lakes and associated food web attributes, we analyzed the U.S. Environmental Protection Agency's National Lakes Assessment (NLA) data. With 1000+ lakes sampled in 2007 and 2012 in a stratified random sampling design, the NLA enables rigorous assessment of lake condition across the continental U.S. We demonstrate that many U.S. lakes are simultaneously experiencing eutrophication and brownification to produce an abundance of "murky" lakes. Overall, "blue" lakes decreased bỹ 18% (46% of lakes in 2007 to 28% in 2012) while "murky" lakes increased by almost 12% (24% of lakes in 2007 to 35.4% in 2012). No statistical differences were observed in the proportions of "green" or "brown" lakes. Regionally, murky lakes significantly increased in the Northern Appalachian, Southern Plains, and Xeric ecoregions. Murky lakes exhibited the highest epilimnetic chlorophyll a concentrations, cyanobacterial densities, and microcystin concentrations. Total zooplankton biomass was also highest in murky lakes, primarily due to increased rotifer and copepod biomass. However, zooplankton : phytoplankton biomass ratios were low, suggesting reduced energy transfer to higher trophic levels. These results emphasize that many lakes in the U.S. are simultaneously "greening" and "browning", with potentially negative consequences for water quality and food web structure.

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“…Current changes in aquatic ecosystems include warming of surface waters, shortened periods of ice cover and hence longer growing seasons, as well as altered light and nutrient availability through increased strength of stratification (Adrian et al 2009;Doney et al 2012). At the same time, many temperate lakes experience an increase in water color that is predicted to continue over the next century (Hansson et al 2013;de Wit et al 2016;Weyhenmeyer et al 2016). Causes are still debated, but include increasing input of dissolved organic carbon (DOC) in the form of humic and fulvic acids due to altered land-use patterns, changed precipitation frequencies, and reversal from acidification (Hongve et al 2004;Evans et al 2005;Kritzberg and Ekstr€ om 2012;de Wit et al 2016).…”

mentioning

confidence: 99%

“…At the same time, many temperate lakes experience an increase in water color that is predicted to continue over the next century (Hansson et al 2013;de Wit et al 2016;Weyhenmeyer et al 2016). Causes are still debated, but include increasing input of dissolved organic carbon (DOC) in the form of humic and fulvic acids due to altered land-use patterns, changed precipitation frequencies, and reversal from acidification (Hongve et al 2004;Evans et al 2005;Kritzberg and Ekstr€ om 2012;de Wit et al 2016). Both warming and browning can have pronounced impacts on aquatic organisms, their metabolism and ecological interactions.…”

mentioning

confidence: 99%

Primary producers or consumers? Increasing phytoplankton bacterivory along a gradient of lake warming and browning

Wilken

Soares

Urrutia‐Cordero

et al. 2017

Limnology & Oceanography

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Eukaryotic phytoplankton form the basis of aquatic food webs and play a key role in the global carbon cycle. Many of these evolutionarily diverse microalgae are also capable of feeding on other microbes, and hence simultaneously act both as primary producers and consumers. The net ecosystem impact of such mixotrophs depends on their nutritional strategy which is likely to alter with environmental change. Many temperate lakes are currently warming at unprecedented rates and are simultaneously increasing in water color (browning) due to increased run‐off of humic substances. We hypothesized that the resulting reduction in light intensity and increased bacterial abundances would favor mixotrophic phytoplankton over obligate autotrophs, while higher temperatures might boost their rates of bacterivory. We tested these hypotheses in a mesocosm experiment simulating a gradient of increasing temperature and water color in temperate shallow lakes as expected to occur over the coming century. Mixotrophs showed a faster increase in abundance under the climate change scenario during spring, when they dominated the phytoplankton community. Furthermore, both bacterial abundances and rates of phytoplankton bacterivory increased under future climate conditions. Bacterivory contributed significantly to phytoplankton resource acquisition under future climate conditions, while remaining negligible throughout most of the season in treatments resembling today's conditions. Hence, to our knowledge, we here provide the first evidence for an increasing importance of bacterivory by phytoplankton in future temperate shallow lakes. Such a change in phytoplankton nutritional strategies will likely impact biogeochemical cycles and highlights the need to conceptually integrate mixotrophy into current ecosystem models.

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Current Browning of Surface Waters Will Be Further Promoted by Wetter Climate

Cited by 280 publications

References 46 publications

Raw Water Quality and Pretreatment in Managed Aquifer Recharge for Drinking Water Production in Finland

Raw Water Quality and Pretreatment in Managed Aquifer Recharge for Drinking Water Production in Finland

Fewer blue lakes and more murky lakes across the continental U.S.: Implications for planktonic food webs

Primary producers or consumers? Increasing phytoplankton bacterivory along a gradient of lake warming and browning

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