Historical Nutrient Enrichment of Lake Ontario: Paleolimnological Evidence

1991 ◽  
Vol 48 (8) ◽  
pp. 1529-1538 ◽  
Author(s):  
Claire L. Schelske
Keyword(s):  
Primary Productivity ◽  
Nutrient Enrichment ◽  
Lake Ontario ◽  
Phosphorus Loading ◽  
Moderate Increase ◽  
Sediment Record ◽  
Carbon Production ◽  
European Settlement ◽  
Exponential Increase ◽  
Major Nutrients

Recent studies of Lake Ontario show four periods of nutrient enrichment that can be identified from the sediment record in this phosphorus-limited system: pristine phosphorus loads (early 1800s before European settlement), moderate increase in phosphorus loading after settlement (beginning approximately 1850), exponential increase in phosphorus loading from urban sources (approximately 1940–70), and decreased phosphorus loading as the result of phosphorus abatement strategies (beginning in mid-1970s). Paleolimnological data are used to infer new paradigms about historical dynamics and cycling of major nutrients. The temporal pattern of organic carbon production closely parallels changes in phosphorus loading. Silica supplies which were replete for diatom production before forest clearance in the mid-1800s became limiting for diatom production in the summer epilimnion after 1865 and in the water column after 1950. Silica reserves were depleted by increased diatom production and sedimentation that resulted from increased phosphorus loading. Biologically induced precipitation of calcite began after 1940 as an indirect effect of increased urban phosphorus loading on primary productivity. Calcite began to be precipitated when historical increases in CO2 utilized for primary productivity increased epilimnetic pH and the calcium carbonate saturation product was exceeded.

Historical Relationships between Phosphorus Loading and Biogenic Silica Accumulation in Bay of Quinte Sediments

1985 ◽  
Vol 42 (8) ◽  
pp. 1401-1409 ◽  
Author(s):  
Claire L. Schelske ◽  
Daniel J. Conley ◽  
William F. Warwick
Keyword(s):  
Biogenic Silica ◽  
Drainage Basin ◽  
Sediment Accumulation ◽  
Lake Ontario ◽  
Domestic Sewage ◽  
Phosphorus Loading ◽  
Accumulation Rates ◽  
Urban Centers ◽  
European Settlement ◽  
Historical Relationship

Sediments from Warwick's 1972 Glenora-B core from the Bay of Quinte, Lake Ontario, were analyzed to compare the historical relationship between the accumulation of biogenic silica (BSi) and total phosphorus (TP). The similarities in patterns provide evidence that increased phosphorus (P) inputs caused increased diatom production and BSi accumulation. BSi accumulation increased soon after initial European settlement by French Sulpicians in 1669 and reached maximum levels during the early 1850s when forest clearance and erosion of the deforested drainage basin increased sediment accumulation rates 110-fold compared with rates before 1669. Maximum rates of BSi and TP accumulation increased 170-fold and 150-fold, respectively, during the same period. Ratios of BSi:TP were about sixfold greater in the sediments deposited after 1888 than in those deposited prior to 1669, indicating that the proportion of available P in TP inputs increased with increased disposal of domestic sewage into the bay as populations shifted to urban centers. Increases in BSi accumulation above the Ambrosia horizon (dated at 1852) indicate that sediments can be a significant sink for BSi. Although the onset of Si depletion cannot be confirmed with data from this core, there is clear evidence that BSi accumulation increased as the result of increased P inputs.

Impacts of Phosphorus Loading Temporal Pattern on Benthic Algae Growth in Lake Ontario

2021 ◽  
pp. 126449
Author(s):  
Yuan Hui ◽  
Zhenduo Zhu ◽  
Joseph F. Atkinson ◽  
Angshuman M. Saharia
Keyword(s):  
Temporal Pattern ◽  
Lake Ontario ◽  
Benthic Algae ◽  
Phosphorus Loading ◽  
Algae Growth

scholarly journals Path Planning for 3-D In-Hand Manipulation of Micro-Objects Using Rotation Decomposition

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 986
Author(s):  
Pardeep Kumar ◽  
Michaël Gauthier ◽  
Redwan Dahmouche
Keyword(s):  
Main Idea ◽  
Robotic Manipulation ◽  
Moderate Increase ◽  
Adhesion Forces ◽  
Dexterous Manipulation ◽  
Confined Spaces ◽  
Direct Extension ◽  
Exponential Increase ◽  
Simulation Results ◽  
Arbitrary Objects

Robotic manipulation and assembly of micro and nanocomponents in confined spaces is still a challenge. Indeed, the current proposed solutions that are highly inspired by classical industrial robotics are not currently able to combine precision, compactness, dexterity, and high blocking forces. In a previous work, we proposed 2-D in-hand robotic dexterous manipulation methods of arbitrary shaped objects that considered adhesion forces that exist at the micro and nanoscales. Direct extension of the proposed method to 3-D would involve an exponential increase in complexity. In this paper, we propose an approach that allows to plan for 3-D dexterous in-hand manipulation with a moderate increase in complexity. The main idea is to decompose any 3-D motion into a 3-D translation and three rotations about specific axes related to the object. The obtained simulation results show that 3-D in-hand dexterous micro-manipulation of arbitrary objects in presence of adhesion forces can be planned in just few seconds.

Plants sustain the terrestrial silicon cycle during ecosystem retrogression

Science ◽  
2020 ◽  
Vol 369 (6508) ◽  
pp. 1245-1248 ◽  
Author(s):  
F. de Tombeur ◽  
B. L. Turner ◽  
E. Laliberté ◽  
H. Lambers ◽  
G. Mahy ◽  
...  
Keyword(s):  
Biological Control ◽  
Carbon Cycling ◽  
Primary Productivity ◽  
Terrestrial Ecosystems ◽  
Ecosystem Development ◽  
Silicon Cycle ◽  
Weathered Soils ◽  
Major Nutrients ◽  
Silicon Sources

The biogeochemical silicon cycle influences global primary productivity and carbon cycling, yet changes in silicon sources and cycling during long-term development of terrestrial ecosystems remain poorly understood. Here, we show that terrestrial silicon cycling shifts from pedological to biological control during long-term ecosystem development along 2-million-year soil chronosequences in Western Australia. Silicon availability is determined by pedogenic silicon in young soils and recycling of plant-derived silicon in old soils as pedogenic pools become depleted. Unlike concentrations of major nutrients, which decline markedly in strongly weathered soils, foliar silicon concentrations increase continuously as soils age. Our findings show that the retention of silicon by plants during ecosystem retrogression sustains its terrestrial cycling, suggesting important plant benefits associated with this element in nutrient-poor environments.

The Lake Ontario Life Support System

1987 ◽  
Vol 44 (12) ◽  
pp. 2230-2240 ◽  
Author(s):  
D. R. S. Lean ◽  
H-J. Fricker ◽  
M. N. Charlton ◽  
R. L. Cuhel ◽  
F. R. Pick
Keyword(s):  
Primary Productivity ◽  
Life Support ◽  
Lake Ontario ◽  
Trophic Levels ◽  
Phosphorus Concentration ◽  
Nutrient Regeneration ◽  
Particulate Carbon ◽  
Calcium Carbonate Precipitation ◽  
Mixing Processes ◽  
Aquatic Food

Primary productivity provides most of the energy to support aquatic food chains. The rate is not only influenced by available solar radiation but also by temperature, availability of phosphorus, and the influence of physical mixing processes. The special features of Lake Ontario such as changes in phosphorus concentration, calcium carbonate precipitation, and silica deficiency on primary productivity, concentration of particulate carbon, and chlorophyll are discussed. Our lack of understanding of food chain and nutrient regeneration processes is illustrated through our failure to balance carbon production with losses through zooplankton grazing and sedimentation. It was demonstrated, however, that bacteria are not responsible for nutrient regeneration through "mineralization" but nutrients are effectively recycled in the water column at the second and third trophic levels.

Recent Changes in the Phytoplankton of the Bay of Quinte, Lake Ontario: the Relative Importance of Fish, Nutrients, and Other Factors

1989 ◽  
Vol 46 (5) ◽  
pp. 770-779 ◽  
Author(s):  
K. H. Nicholls ◽  
D. A. Hurley
Keyword(s):  
Phytoplankton Biomass ◽  
White Perch ◽  
Control Period ◽  
Model Fitting ◽  
Correlation Coefficients ◽  
Lake Ontario ◽  
Multiple Regression Model ◽  
Phosphorus Loading ◽  
Alosa Pseudoharengus ◽  
Blue Green Algae

A 50% reduction in phosphorus loading to the upper Bay of Quinte (Lake Ontario) from municipal sources in 1977 was followed by a major decline in phytoplankton biomass in 1978. However, by 1984–85, biomasses again approached those of the pre-phosphorus control period, despite continued low phosphorus loadings. No major shifts in phytoplankton composition occurred; domination by the diatoms Melosira and Stephanodiscus spp. and the blue-green algae Anabaena and Aphanizomenon spp. has continued. Highly significant positive correlation coefficients (r = 0.92–0.98) were found for phytoplankton — fish relationships during both the pre- and postphosphorus removal periods which coincided with pre- and postdie-off periods of white perch (Morone americana) and alewife (Alosa pseudoharengus). For the entire 16-yr period of data collection, a multiple regression model fitting upper bay phytoplankton biomass (with an adjusted R2 of 0.83) was developed with five input variables. White perch biomass alone explained more than 50% of the variance in the model. It is hypothesized that trophic interactions among other biotic components in the Bay of Quinte may be very important in controlling phytoplankton biomass.

Sediment Record of Biogeochemical Responses to Anthropogenic Perturbations of Nutrient Cycles in Lake Ontario

1988 ◽  
Vol 45 (7) ◽  
pp. 1291-1303 ◽  
Author(s):  
Claire L. Schelske ◽  
John A. Robbins ◽  
Wayne S. Gardner ◽  
Daniel J. Conley ◽  
Richard A. Bourbonniere
Keyword(s):  
Sediment Cores ◽  
Lake Ontario ◽  
Inorganic Phosphorus ◽  
Relative Increase ◽  
Stratigraphic Correlation ◽  
Sediment Record ◽  
Calcite Precipitation ◽  
Order Of Magnitude ◽  
Recent Sediments ◽  
Secondary Consequence

Two sediment cores collected from the Rochester basin of Lake Ontario were dated with 210Pb and stratigraphic correlation and analyzed to determine whether nutrient accumulation with time was consistent with previous computer-simulated total phosphorus (TP) loadings. Relative increases in TP and nonapatite inorganic phosphorus (NAIP) accumulation were less than the fivefold increase in TP loading from 1800 to 1950 predicted independently from Chapra's simulation model. In addition, increases in TP accumulation occurred mainly after 1940 and the proportion of NAIP relative to TP increased in one core and decreased in the other. Of the nutrients studied, only increases in organic carbon (OC) paralleled the increases in modelled TP loadings. The relative increase in inorganic carbon (IC) was greatest, with accumulation increasing an order of magnitude after 1940 in one core. This large increase in IC, amounting to 20% calcite in recent sediments, was attributed to biologically induced calcite precipitation, a secondary consequence of increased planktonic photosynthetic removal of carbon dioxide that resulted from accelerated eutrophication after 1940 when modelled TP concentrations increased rapidly. Biogenic silica (BSi) accumulation, an indicator of increased diatom production, peaked between 1850 and 1870 when increases in TP and NAIP fluxes were minimal. Results provide evidence that historic biogeochemical responses inferred from OC, IC, and BSi accumulation in the sediment record provide stronger signals of phosphorus enrichment effects than can be inferred directly from changes in accumulation of different forms of phosphorus in the sediment record.

Recycling of Polyphosphate accumulated in picoplankton in coastal Lake Ontario

2020 ◽  
Author(s):  
Maria Dittrich ◽  
Jiying Li ◽  
Diane Diane Plouchart ◽  
Arthur Zastepa
Keyword(s):  
Primary Productivity ◽  
Lake Ontario ◽  
Aquatic Systems ◽  
Marine Waters ◽  
Coastal Lake ◽  
Common View ◽  
Low Phosphorus ◽  
Essential Nutrient ◽  
P Recycling ◽  
The Common

<p>Phytoplankton can accumulate polyphosphate (polyP) to alleviate the limitation of essential nutrient phosphorus (P). Yet polyP metabolisms in aquatic systems and their roles in P biogeochemical cycle remain elusive. Previously reported polyP enrichment in low-phosphorus oligotrophic marine waters contradicts the common view of polyP as a luxury P-storage molecule. Here, we show that in a P-rich eutrophic bay of Lake Ontario, planktonic polyP is controlled by multiple mechanisms and responds strongly to seasonal variations. Plankton accumulates polyP as P storage under high-P conditions via luxury uptake and uses it under acute P stress. Low phosphorus also triggers enrichment of polyP that can be preferentially recycled to attenuate P lost. We discover that picoplankton, despite their low production rates, are responsible for the dynamic polyP metabolisms. Picoplankton store and liberate polyP to support the high primary productivity of blooming algae. PolyP mechanisms enable and P exchange and efficient P recycling on the ecosystem and even larger scales.</p>

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