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Kjensmo, Johannes

doi:10.1023/a:1003035705729

Cited by 28 publications

(7 citation statements)

References 6 publications

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“…Hutchinson [1957] refers to Hemmelsdorfer See, near Kiel in Germany, which was flooded by a storm from the Baltic in 1872 and remained meromictic until the 1930s. Other deep lakes have become meromictic by inflowing salt water from deicing roads (Schalkenmehrener Maar [see Scharf and Oehms, 1992]) or lost meromictic stability by inflow of road salt to the epilimnion [Kjensmo, 1997].…”

Section: Ectogenic and Crenogenic Meromixismentioning

confidence: 99%

Stratification of lakes

Boehrer

Schultze

2008

Reviews of Geophysics

567

381

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Many lakes show vertical stratification of their water masses, at least for some extended time periods. Density differences in water bodies facilitate an evolution of chemical differences with many consequences for living organisms in lakes. Temperature and dissolved substances contribute to density differences in water. The atmosphere imposes a temperature signal on the lake surface. As a result, thermal stratification can be established during the warm season if a lake is sufficiently deep. On the contrary, during the cold period, surface cooling forces vertical circulation of water masses and removal of gradients of water properties. However, gradients of dissolved substances may be sustained for periods much longer than one annual cycle. Such lakes do not experience full overturns. Gradients may be a consequence of external inflows or groundwater seepage. In addition, photosynthesis at the lake surface and subsequent decomposition of organic material in the deeper layers of a lake can sustain a gradient of dissolved substances. Three more geochemical cycles, namely, calcite precipitation, iron cycle, and manganese cycle, are known for sustaining meromixis. A limited number of lakes do not experience a complete overturn because of pressure dependence of temperature of maximum density. Such lakes must be sufficiently deep and lie in the appropriate climate zone. Although these lakes are permanently stratified, deep waters are well ventilated, and chemical differences are small. Turbulent mixing and convective deep water renewal must be very effective. As a consequence, these lakes usually are not termed meromictic. Permanent stratification may also be created by episodic partial recharging of the deep water layer. This mechanism resembles the cycling of the ocean: horizontal gradients result from gradients at the surface, such as differential cooling or enhanced evaporation in adjacent shallow side bays. Dense water parcels can be formed which intrude the deep water layer. In the final section, stratification relevant physical properties, such as sound speed, hydrostatic pressure, electrical conductivity, and density, are discussed. The assumptions behind salinity, electrical conductance, potential density, and potential temperature are introduced. Finally, empirical and theoretical approaches for quantitative evaluation from easy to measure properties conclude this contribution.

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Section: Ectogenic and Crenogenic Meromixismentioning

confidence: 99%

Stratification of lakes

Boehrer

Schultze

2008

Reviews of Geophysics

567

381

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“…Road salt has been linked in the transformation of lentic environments from holomictic to meromictic. Lakes in the USA (Judd 1970;Bubeck et al 1971;Hoffman et al 1981;Novotny et al 2008;Novotny and Stefan 2012;Wyman and Koretsky 2018;Dupuis et al 2019;Wiltse et al 2020) and Norway (Kjensmo 1997) have moved toward monomixis or Fig. 5.…”

Section: Effects Of Road Salt In Lentic Environments On Water and Sed...mentioning

confidence: 99%

“…Lakes within 1 km of a gravel highway had higher values for alkalinity, conductivity, total dissolved solids, pH, Ca 2+ , Mg 2+ , hardness, NO 3 -N, NO 2 + NO 3 -N, SO4 2− , and Sr 2+ , which were attributed to the influence of road dust (Gunter 2017). Dust suppressants (MgCl 2 and CaCl 2 ) used to inhibit the generation of dust from roads can also contribute to ion loading in lentic environments, being a source of Ca 2+ , Mg 2+ , and Cl − (Kjensmo 1997;Palmer et al 2011;MacDougall et al 2017). Road dust can also affect water clarity and the composition of lake sediments.…”

Section: Effects Of Road Dust and Dust Suppressants In Lentic Environ...mentioning

confidence: 99%

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The effects of roadways on lakes and ponds: a systematic review and assessment of knowledge gaps

et al. 2022

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As the global population increases, the expansion of road networks has led to the destruction and disturbance of terrestrial and aquatic habitats. Road-related stressors have significant effects on both lotic and lentic habitats. While there are several systematic reviews that evaluate the effects of roads on lotic environments, there are none that consider their effects on lentic habitats only. We conducted a literature review to achieve two objectives: 1) to summarize the effects of roads on the physical, chemical, and biological properties of lentic environments; and 2) to identify biases and gaps in our current knowledge of the effects of roads on lentic habitats so that we could find promising areas for future research. Our review found 172 papers published between 1970-2020. The most frequently studied stressors associated with roads included road salt and heavy metal contamination (67 and 43 papers respectively), habitat fragmentation, (37 papers) and landscape change (14 papers). These stressors can lead to alterations in conductivity and chloride levels, changes in lake stratification patterns, increases in heavy metal concentrations in water and organisms, and significant mortality as amphibians disperse across roadways. We also identified a variety of other stressors that may be understudied based on their frequency of appearance in our search results, including polycyclic aromatic hydrocarbons, road dust, increased accessibility, hydrological changes, noise pollution, dust suppressants, sedimentation, invasive species introductions, and water withdrawal. Our review indicated that there are strong geographic biases in published studies, with 57.0% examining North American sites and 30.2% examining European sites. Furthermore, there were taxonomic biases in the published literature, with most studies focusing on amphibians (41.7%), fish (15.6%), and macroinvertebrates (14.6%), while few considered zooplankton (8.3%), diatoms (7.3%), amoebas (5.2%), water birds (3.1%), reptiles (2.1%) and macrophytes (1.0%). Based on our review, we have identified promising areas for future research for each of the major stressors related to roadways. However, we speculate that rectifying the geographic and taxonomic bias of our current knowledge could significantly advance our understanding of the impacts of roads on lentic environments, thereby better informing environmental management of these important habitats.

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“…Continuous reduction in oxygen can decrease the habitability of a lake leading to a "dead lake" with little biotic activity (Koretsky et al, 2012;MacLeod et al, 2011). Examples of significant vertical stratification caused by road salt is tied to formation of suburbs near a lake in California (Judd, 1970), urban and rural lakes in Michigan (Judd, 1970;Koretsky et al, 2012;MacLeod et al, 2011) and rural lakes in Norway (Kjensmo, 1997).…”

Section: Density Stratification Of Lakesmentioning

confidence: 99%

Geostatistical modelling of in-stream chloride concentrations across seasonal flow states in three urbanizing watersheds

Ash¹

2022

Preprint

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Road salt causes increasing environmental chloride (Cl-) concentrations which threaten aquatic ecosystems. Environment Canada recommends that road authorities should develop salt management plans including identification of salt vulnerable areas. In this thesis, a Spatial Stream Network (SSN) geostatistical modelling approach was used with seasonal longitudinal field data to develop reach scale models of in-stream Cl- concentrations in three Southern Ontario watersheds. Significance of potential drivers (lane length density (LLD), agricultural & undifferentiated rural land (AURL), and permeability of surficial geology) of stream Cl- were assessed. Results suggest that SSN models are not consistently better than Euclidean models across watersheds. Unexpectedly, LLD was the most important predictor in the rural watershed, and AURL was most important in the urban watershed. Results also show that spatial structure in stream Cl- concentrations was lost under higher flow conditions, which has important implications for when data should be collected to map salt vulnerable areas.

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Untitled

Cited by 28 publications

References 6 publications

Stratification of lakes

Stratification of lakes

The effects of roadways on lakes and ponds: a systematic review and assessment of knowledge gaps

Geostatistical modelling of in-stream chloride concentrations across seasonal flow states in three urbanizing watersheds

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