Nitrogen Transformations in Lake Ontario

1987 ◽  
Vol 44 (12) ◽  
pp. 2133-2143 ◽  
Author(s):  
D. R. S. Lean ◽  
R. Knowles
Keyword(s):  
Surface Waters ◽  
Lake Ontario ◽  
Ammonium Uptake ◽  
Small Cells ◽  
Nitrogen Transformations ◽  
Size Fractionation ◽  
Nitrate Losses ◽  
Zooplankton Excretion ◽  
Highly Correlated ◽  
Chemoautotrophic Bacteria

Concentrations of ammonium plus nitrite in Lake Ontario were highly correlated with ammonium regeneration from zooplankton excretion (r = 0.966), inferring that elevated nitrite concentrations result from nitrification. Nitrapyrin-sensitive dark 14C-labeled bicarbonate assays confirmed high rates of nitrification by chemoautotrophic bacteria. 15N-labeled nitrate experiments showed that nitrate, not ammonium, was the principal form of N used for total microbial protein synthesis. Size fractionation experiments also suggested that small cells were responsible for most of the ammonium uptake, while large cells used mostly nitrate. Nitrate depletion in the surface waters during summer stratification resulted from movement to particulate N, nitrite, and ammonium as well as losses in particulate N due to sedimentation. At least one third, however, was unaccounted for (i.e. 30 mg N∙m−2∙d−1) and may have been converted to protein which would move up the food chain to larger organisms (e.g. fish) not sampled during conventional water chemistry. Nitrous oxide profiles showed that nitrate losses through denitrification are unlikely to occur. Consequently, unless nitrate loading to Lake Ontario is reduced, nitrate concentrations should be expected to continue to increase.

scholarly journals Prominent bacterial heterotrophy and sources of <sup>13</sup>C-depleted fatty acids to the interior Canada Basin

2013 ◽  
Vol 10 (11) ◽  
pp. 7065-7080 ◽  
Author(s):  
S. R. Shah ◽  
D. R. Griffith ◽  
V. Galy ◽  
A. P. McNichol ◽  
T. I. Eglinton
Keyword(s):  
Fatty Acids ◽  
Particulate Matter ◽  
Organic Carbon ◽  
Suspended Particulate Matter ◽  
Surface Waters ◽  
Canada Basin ◽  
The Arctic ◽  
Deep Basin ◽  
Suspended Particulate ◽  
Chemoautotrophic Bacteria

Abstract. In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and 13C-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are more 13C-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20–24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.

Size fractionation highlights the mobility of copper from urban stormwater to river

2021 ◽  
Author(s):  
Du Phuc Tho Dang ◽  
Béatrice Béchet ◽  
Liliane Jean-Soro
Keyword(s):  
Surface Waters ◽  
Urban Areas ◽  
Stormwater Runoff ◽  
Essential Element ◽  
Aquatic Organisms ◽  
Road Transport ◽  
Major And Trace Elements ◽  
Copper Accumulation ◽  
Size Fractionation ◽  
Particulate Copper

&lt;p&gt;Copper is an ubiquitous essential element but also toxic to aquatic organisms, Environmental Quality Standards being 1 &amp;#181;g.L&lt;sup&gt;-1&lt;/sup&gt; for surface water (annual mean concentration). Rivers and estuaries are mainly concerned by copper accumulation in sediments and in organisms. Copper can originate from various manufactured products (antifouling painting, vineyards fungicides, brake linings&amp;#8230;.) and anthropic activities (industrial, landfills&amp;#8230;). As a result, copper French median concentration in oysters is about 200 mg.kg&lt;sup&gt;-1&lt;/sup&gt; DM (Ifremer, 2017).&lt;/p&gt;&lt;p&gt;Transportation, especially road transport, is the main French source of copper air emissions (92% of total emissions) (CITEPA, 2019). Then, urban areas, mainly impervious, constitute a major non-point source of copper from abrasion of brake pads and tires, and fuels. This contaminant is released from the road surfaces through stormwater runoff directly to water bodies or after collection in sustainable urban drainage systems (SUDS). As the epuration performance of SUDS for copper was shown to be low, this study is carried out to evaluate if copper mobility can be explained by its physical speciation. The distribution of copper among dissolved, colloidal and particulate fractions is studied by size fractionation, assuming that the mobility of copper is related to a high dissolved and colloidal occurrence.&lt;/p&gt;&lt;p&gt;The study site is a retention-infiltration basin collecting the runoff waters of the main bridge of Nantes (France; about 90&amp;#160;000 vehicles/day), and overflowing to the Loire river . Size fractionation by in series filtration and ultrafiltration was performed on stormwater runoff and surface waters sampled within the basin. Five fractions were analyzed for major and trace elements: ] ; 8&amp;#181;m ], ] 8&amp;#181;m ; 1,2&amp;#181;m ], ] 1,2&amp;#181;m ; 0,45&amp;#181;m ], ] 0,45&amp;#181;m ; 5kDa ] and ] 5kDa. Among these fractions ] ; 8&amp;#181;m ] correspond to particulate copper, ] 8&amp;#181;m ; 1,2&amp;#181;m ], ] 1,2&amp;#181;m ; 0,45&amp;#181;m ], ] 0,45&amp;#181;m ; 5kDa ] to colloidal copper and ] 5kDa ; [ to dissolved copper. Size fractionations were implemented for 8 samples with 2 replicates for each sample and over 1 year. 0.45 &amp;#181;m filtrations were also conducted as a reference.&lt;/p&gt;&lt;p&gt;The total copper concentration in runoff was around 100&amp;#181;g.L&lt;sup&gt;-1&lt;/sup&gt;, which is in the upper part of the concentrations observed in the area of Nantes in SUDS. The results of the size fractionation are as follows : 1) for the stormwater runoffs, particulate copper is about 70% of the total amount, colloidal copper is present for 20% and 10% of dissolved copper is measured. Thus 30 % of copper are mobile; 2) for the surface waters in the basin, the distribution of copper among the dissolved, colloidal and particulate fractions, is respectively 20 %, 70 % and 10 %.&lt;/p&gt;&lt;p&gt;We concluded that 1) the concentration of copper is 100 times higher the regulation value for natural environment, and 2) particulate fractions of copper are trapped at the entrance of the basin, and an high content of mobile copper (dissolved and colloidal fractions) is observed in the basin that could either be overflowed or infiltrated in the sub-soil of the basin.&lt;/p&gt;

Composition of Phytoplankton in Surface Waters of Lake Ontario

1966 ◽  
Vol 23 (11) ◽  
pp. 1715-1725 ◽  
Author(s):  
C. Nalewajko
Keyword(s):  
Surface Water ◽  
Surface Waters ◽  
Central Area ◽  
Lake Ontario ◽  
Abundant Species ◽  
Phytoplankton Species ◽  
Important Species ◽  
Asterionella Formosa ◽  
A Cell ◽  
Inshore Waters

Stephanodiscus tenuis Hust., Melosira islandica O. Müll., and Diatoma elongatum (Lyngb.) Ag., on a cell volume basis, were the three most important species from January 1964 to July 1965 in the surface water of Lake Ontario near Gibraltar Point.Stephanodiscus tenuis was by far the most abundant species. It was present during most of the year and accounted for about 87% of the total number of algae present during the spring outbursts.In more central areas of the lake Melosira islandica and Asterionella formosa Hass. replaced Stephanodiscus tenuis as the most important species.On the basis of the major phytoplankton species present the central area of Lake Ontario appears to be oligotrophic. High numbers of Stephanodiscus tenuis in inshore waters may be indicative of a more eutrophic environment.

Differentiation of the Chloride Extrusion Mechanism During Seawater Adaptation of a Teleost Fish, The Cichlid Sarotherodon Mossambicus

1981 ◽  
Vol 93 (1) ◽  
pp. 209-224 ◽  
Author(s):  
J. KEVIN FOSKETT ◽  
CRAIG D. LOGSDON ◽  
TIMOTHY TURNER ◽  
TERRY E. MACHEN ◽  
HOWARD A. BERN
Keyword(s):  
Fluorescence Microscopy ◽  
Time Course ◽  
Chloride Secretion ◽  
Chloride Cell ◽  
Small Cells ◽  
Chloride Cells ◽  
Seawater Adaptation ◽  
Sarotherodon Mossambicus ◽  
Highly Correlated ◽  
Chloride Extrusion

Opercular membranes isolated from the freshwater-adapted euryhaline teleost, Sarotherodon mossambicus, and mounted in Ussing-style chambers, have low conductance and current and do not actively transport chloride. In contrast, membranes isolated from seawater-adapted S. mossambicus have high conductance and generate large currents representing net chloride extrusion. Full development of this chloride secretion process requires 1-2 weeks, the time-course of which provides the first unambiguous measurement of changes in net extrarenal salt secretion associated with a teleost's adaptation to seawater. Tissues from seawater-adapted fish contain typical chloride cells, when observed with the electron microscope, which appear as large cells with fluorescence microscopy after staining with dimethylaminostyrylaethylpyridiniumiodine. These cells are absent from the freshwater tissue, although rudimentary chloride cells are present, appearing as small cells with fluorescence microscopy. Following seawater transfer, the number of chloride cells increases only during the first 3 days. Subsequent chloride cell hypertrophy is highly correlated with the quantity of chloride extrusion. These data strongly implicate the chloride cell as the salt-secretory cell-type. When cortisol was injected into freshwater fish, chloride cell density increased but chloride secretion was not activated. It appears that development of salt extrusion involves increased numbers (controlled, at least in part, by cortisol) and differentiation of chloride cells, including activation of membrane active-transport sites. The opercular membrane from S. mossambicus provides a valuable model for studying these physiological and morphological events.

Seasonal Variations of Temperature and Nutrients in the Surface Waters of Lakes Ontario and Erie

1974 ◽  
Vol 31 (3) ◽  
pp. 275-290 ◽  
Author(s):  
R. Gächter ◽  
R. A. Vollenweider ◽  
W. A. Glooschenko
Keyword(s):  
Primary Production ◽  
Surface Waters ◽  
Seasonal Variations ◽  
Early Onset ◽  
Lake Erie ◽  
Nutrient Concentration ◽  
Spring Bloom ◽  
Lake Ontario ◽  
Nutrient Supply ◽  
Nutrient Patterns

During 1970, temperature and nutrient distributions were measured in surface waters of lakes Ontario (12 cruises) and Erie (10 cruises). Nutrient patterns are compared and discussed in relation to temperature, primary production, and nutrient sources.In Lake Erie, due to the early onset of the phytoplankton spring bloom, nutrient concentration started to decrease much earlier than in Lake Ontario. During spring, patterns of nutrients, chlorophyll a, and primary production were influenced by the thermal bar in Lake Ontario. In Lake Erie the nutrient supply controlled such patterns. In Lake Erie inorganic nutrients were depleted lake-wide in summer; in Lake Ontario, nutrients were highest in regions where upwelling occurred or inputs were high. Due to the earlier onset of fall overturn in Lake Erie, the nutrient concentration started to increase earlier in the fall than in Lake Ontario.

scholarly journals Prominent bacterial heterotrophy and sources of <sup>13</sup>C-depleted fatty acids to the interior Canada Basin

2013 ◽  
Vol 10 (4) ◽  
pp. 6695-6736 ◽  
Author(s):  
S. R. Shah ◽  
D. R. Griffith ◽  
V. Galy ◽  
A. P. McNichol ◽  
T. I. Eglinton
Keyword(s):  
Fatty Acids ◽  
Particulate Matter ◽  
Organic Carbon ◽  
Suspended Particulate Matter ◽  
Surface Waters ◽  
Canada Basin ◽  
The Arctic ◽  
Deep Basin ◽  
Suspended Particulate ◽  
Chemoautotrophic Bacteria

Abstract. In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to depth, particularly as our baseline understanding of organic carbon cycling in the deep basin is limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are 13C-enriched compared to even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. A source of saturated even-numbered fatty acids is also suggested below surface waters which could represent contributions from laterally advected organic carbon or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20–24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon on benthic particulate matter. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.

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