Lake Ontario: the predominant source of triazine herbicides in the St. Lawrence River

2000 ◽  
Vol 57 (S1) ◽  
pp. 78-85 ◽  
Author(s):  
T -T Pham ◽  
B Rondeau ◽  
H Sabik ◽  
S Proulx ◽  
D Cossa
Keyword(s):  
Lake Ontario ◽  
Quebec City ◽  
Triazine Herbicides ◽  
Triazine Herbicide ◽  
Ottawa River ◽  
River Water Samples ◽  
The Difference ◽  
High Concentrations ◽  
Dissolved Phase ◽  
St Lawrence River

To estimate triazine herbicide concentrations and sources in the St. Lawrence River, water samples were collected at its two major inlets (from the Great Lakes, Cornwall station, and from the Ottawa River, Carillon station) and at the outlet (Quebec City station) of the fluvial section. Sampling was carried out over an 18-month period between 1995 and 1996. Triazines were detected only in the dissolved phase at concentrations ranging from 2 to 91, from <0.4 to 15, and from <0.4 to 13 ng·L-1 for atrazine, cyanazine, and simazine, respectively. Dilution models show that, despite the presence of sporadically high concentrations of herbicides in St. Lawrence tributaries during periods of their application, loading from the tributaries is minor. Mass balance calculations show that Lake Ontario is clearly the main source of triazines (~90%) to the St. Lawrence River. During the 1995-1996 hydrological year, Lake Ontario contributed 15.1 × 103 of the 16.6 × 103 kg of atrazine outflowing the St. Lawrence River to the estuary. The difference (1.5 × 103 kg·year-1) can be attributed to tributaries in Quebec, which represent 0.75% of the amount of atrazine spread on farmlands. There is no evidence of the degradation of triazine compounds during their transit time in the river.

Water at the Outlet of the St. Lawrence River Part I - Sampling and Major Cations

1993 ◽  
Vol 28 (2) ◽  
pp. 415-432
Author(s):  
C. Barbeau ◽  
J.-B. Sérodes ◽  
M. Paquet
Keyword(s):  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Water Treatment Plant ◽  
Daily Basis ◽  
High Flow ◽  
Quebec City ◽  
Water Composition ◽  
Many Sources ◽  
Dissolved Phase ◽  
St Lawrence River

Abstract The St. Lawrence River exports important loads of contaminants to the estuary, but good estimates of annual loadings are presently not available. During two years (1989–91), discrete and composite samples were taken on a daily basis at the water intake of the drinking water treatment plant of Lévis in front of Québec City. Our data indicate that discrete samples are representative of the bulk of the water and that magnesium or calcium measurements provide valuable information on the species transported to the estuary in the dissolved phase. Any decrease in magnesium concentrations at Lévis is the result of relative flow increases from the tributaries of the river. Using high flow episodes in tributaries and daily magnesium measurements at Lévis, the time of transport of the dissolved phase from many sources along the river has been evaluated. At high flow, the time of transport from the Carillon Dam (on the Ottawa River) to Lévis is 11 days, while it is 8 days from Beauharnois. With these data, a predictive model using magnesium (or calcium) as the chemical parameter characterizing the dissolved phase of the St. Lawrence River at the mouth of the estuary was developed. Loadings to the estuary of any dissolved contaminant can now be estimated by combining daily calculated flow values with daily measured water composition at Levis.

Water at the Outlet of the St. Lawrence River Part II - Suspended Matter and Solid Loadings from 1989 to 1991

1993 ◽  
Vol 28 (2) ◽  
pp. 433-450
Author(s):  
C. Barbeau ◽  
J.-B. Sérodes ◽  
J.-E. Côté
Keyword(s):  
Suspended Matter ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Lake Ontario ◽  
Water Treatment Plant ◽  
Daily Basis ◽  
Mean Value ◽  
Quebec City ◽  
High Concentration ◽  
St Lawrence River

Abstract During two years (1989–91), water samples of the St. Lawrence River were taken on a daily basis at the intake of the drinking water treatment plant of Lévis, in front of Québec City, and analyzed for suspended matter. Data indicate that the physical behaviour of the particulate phase is identical to that observed for the dissolved phase (see paper I) and, in contrast to the steady concentrations at the exit of Lake Ontario, the suspended matter at the outlet of the St. Lawrence River varies on a monthly and seasonal basis. The concentration varies from a mean value of 8 mg/L in winter to 30 mg/L in spring, 10 to 15 mg/L in summer, and 14 to 19 mg/L during fall, with an annual mean of 17 mg/L. The maxima occur in spring and are higher than 100 mg/L (108–179). High concentrations of solids are observed at dates of high flow, except in November, when a heavy solid discharge is noted independently of water flow. Tributaries on the south shore contribute little to the flow of water but they carry half of the suspended matter at Levis during periods of low concentration of solids and more than the two-thirds during periods of high concentration. The calculated sediment load of the St. Lawrence River at Lévis for 1990 is 7 million tons and the annual load based on the 1989–91 period is 6.6 million tons. More than 95% of the solids come from downstream of Lake Ontario. Seasonally, 50% of the annual load occurs during spring, 10% in winter, while fall and summer contributes each 20%.

Colonization, Ecology, and Population Structure of the "Quagga'' Mussel (Bivalvia: Dreissenidae) in the Lower Great Lakes

1993 ◽  
Vol 50 (11) ◽  
pp. 2305-2314 ◽  
Author(s):  
Edward L. Mills ◽  
Ron M. Dermott ◽  
Edward F. Roseman ◽  
Donna Dustin ◽  
Eric Mellina ◽  
...  
Keyword(s):  
Great Lakes ◽  
Zebra Mussel ◽  
Dreissena Polymorpha ◽  
Lake Erie ◽  
New York State ◽  
Lake Ontario ◽  
Quebec City ◽  
Quagga Mussel ◽  
Eastern Basin ◽  
St Lawrence River

An invasive dreissenid mussel given the working name of "quagga" has a present (spring 1993) distribution in the Laurentian Great Lakes from the western basin of Lake Erie to Quebec City. In Lake Erie, quaggas were collected as early as 1989 and now are most common in the eastern basin. In Lakes Erie and Ontario, proportions of quaggas increased with depth and decreasing water temperature. In the eastern basin of Lake Erie, quaggas outnumbered zebra mussel (Dreissena polymorpha) by 14 to 1 in deeper waters (>20 m). In Lake Ontario, quaggas were observed at depths as great as 130 m, and both quagga and zebra mussel were found to survive at depths (>50 m) where temperatures rarely exceed 5 °C. Quaggas were sparse or absent along inland waterways and lakes of New York State. Mean shell size of quagga mussel was larger than that of zebra mussel at sites in the Niagara River, Lake Ontario, and the St. Lawrence River. The largest quaggas (38 mm) were observed in the St. Lawrence River at Cape Vincent.

Mercury and Organochlorinated Hydrocarbons in Surficial Sediments of the St. Francis

1991 ◽  
Vol 26 (1) ◽  
pp. 41-60 ◽  
Author(s):  
Harm H. Sloterdijk
Keyword(s):  
Lake Ontario ◽  
Toxic Substances ◽  
Surficial Sediments ◽  
Chlorinated Pesticides ◽  
Polybrominated Biphenyls ◽  
Local Sources ◽  
High Concentrations ◽  
General Source ◽  
St Lawrence River

Abstract In order to evaluate the role of Lake St. Francis as a depositional zone for toxic substances coming from Lake Ontario and the international section of the St. Lawrence River, a sediment survey was carried out in the early eighties. Samples from 98 stations were analyzed for particle size, organic carbon, mercury (Hg), polychlorinated biphenyls (PCB’s), and organo-chlorinated pesticides, and those from 10 stations for chlorobenzenes, pentachlorophenol, and polybrominated biphenyls. Only PCB’s and Hg were found at high concentrations, up to 1900 and 1500 ng·g−1, respectively. Although Lake Ontario remains a general source of contaminants (especially PCB’s and mirex) for the Quebec stretch of the St. Lawrence River, its contribution to Lake St. Francis is of less importance than that of local sources along the Canada/USA international section of the rivers, such as Cornwall (Hg) and the Massena area (PCB’s).

Loadings of Selected Chemicals into the St. Lawrence River System from Lake Ontario, 1986/87

1989 ◽  
Vol 24 (4) ◽  
pp. 589-608 ◽  
Author(s):  
I.K. Tsanis ◽  
J. Biberhofer ◽  
C.R. Murthy ◽  
A. Sylvestre
Keyword(s):  
Mass Balance ◽  
Lake Ontario ◽  
River System ◽  
Vertical Gradient ◽  
The South ◽  
Measured Concentration ◽  
Chemical Monitoring ◽  
The North ◽  
Loading Estimates ◽  
St Lawrence River

Abstract Determination of the mass output through the St. Lawrence River outflow system is an important component in computing mass balance of chemical loadings to Lake Ontario. The total flow rate in the St. Lawrence River System at the Wolfe Island area was calculated from detailed time series current meter measurements from a network of current meters and Lagrangian drifter experiments. This flow is roughly distributed in the ratio of 55% to 45% in the South and North channel, respectively. Loading estimates of selected chemicals have been made by combining the above transport calculations with the ongoing chemical monitoring data at the St. Lawrence outflow. A vertical gradient in the concentration of some organic and inorganic chemicals was observed. The measured concentration for some of the chemicals was higher during the summer months and also is higher in the South Channel than in the North Channel of the St. Lawrence River. These loading estimates are useful not only for modelling the mass balance of chemicals in Lake Ontario but also for serving as input loadings to the St. Lawrence River system from Lake Ontario.

Zebra Mussels as Biomonitors for Organic Contaminants in the Lower Great Lakes

1996 ◽  
Vol 31 (2) ◽  
pp. 411-432 ◽  
Author(s):  
Michael E. Comba ◽  
Janice L. Metcalfe-Smith ◽  
Klaus L.E. Kaiser
Keyword(s):  
Great Lakes ◽  
Organic Contaminants ◽  
Lake Erie ◽  
Soft Tissues ◽  
Lake Ontario ◽  
Dry Weight ◽  
Zebra Mussels ◽  
Organic Contamination ◽  
Contamination Levels ◽  
St Lawrence River

Abstract Zebra mussels were collected from 24 sites in Lake Erie, Lake Ontario and the St. Lawrence River between 1990 and 1992. Composite samples of whole mussels (15 sites) or soft tissues (9 sites) were analyzed for residues of organochlo-rine pesticides and PCBs to evaluate zebra mussels as biomonitors for organic contaminants. Mussels from most sites contained measurable quantities of most of the analytes. Mean concentrations were (in ng/g, whole mussel dry weight basis) 154 ΣPCB, 8.4 ΣDDT, 3.5 Σchlordane, 3.4 Σaldrin, 1.4 ΣBHC, 1.0 Σendosulfan, 0.80 mirex and 0.40 Σchlorobenzene. Concentrations varied greatly between sites, i.e., from 22 to 497 ng/g for ΣPCB and from 0.08 to 11.6 ng/g for ΣBHC, an indication that mussels are sensitive to different levels of contamination. Levels of ΣPCB and Σendosulfan were highest in mussels from the St. Lawrence River, whereas mirex was highest in those from Lake Ontario. Overall, mussels from Lake Erie were the least contaminated. These observations agree well with the spatial contaminant trends shown by other biomoni-toring programs. PCB congener class profiles in zebra mussels are also typical for nearby industrial sources, e.g., mussels below an aluminum casting plant contained 55% di-, tri- and tetrachlorobiphenyls versus 31% in those upstream. We propose the use of zebra mussels as biomonitors of organic contamination in the Great Lakes.

The metachor as a characteristic of the association of electrolytes in aqueous solutions

1984 ◽  
Vol 49 (5) ◽  
pp. 1061-1078 ◽  
Author(s):  
Jiří Čeleda ◽  
Stanislav Škramovský
Keyword(s):  
Aqueous Solutions ◽  
Apparent Volume ◽  
Solutions Of Electrolytes ◽  
Molal Volumes ◽  
The Difference ◽  
High Concentrations ◽  
Experimental Values ◽  
Suitable Characteristic ◽  
Association Of Ions ◽  
Very High

Based on the earlier paper introducing a concept of the apparent parachor of a solute in the solution, we have eliminated in the present work algebraically the effect which is introduced into this quantity by the additivity of the apparent molal volumes. The difference remaining from the apparent parachor after substracting the contribution corresponding to the apparent volume ( for which the present authors suggest the name metachor) was evaluated from the experimental values of the surface tension of aqueous solutions for a set of 1,1-, 1,2- and 2,1-valent electrolytes. This difference showed to be independent of concentration up to the very high values of the order of units mol dm-3 but it was directly proportional to the number of the free charges (with a proportionality factor 5 ± 1 cm3 mol-1 identical for all studied electrolytes). The metachor can be, for this reason, a suitable characteristic for detection of the association of ions and formation of complexes in the solutions of electrolytes, up to high concentrations where other methods are failing.

Distribution and fluxes of metals in the St. Lawrence River from the outflow of Lake Ontario to Qu�bec City

1991 ◽  
Vol 53 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Ken R. Lum ◽  
K. L. E. Kaiser ◽  
C. Jaskot
Keyword(s):  
Lake Ontario ◽  
St Lawrence River

scholarly journals Thunderstorm outflows preceding epidemics of asthma during spring and summer

Thorax ◽  
2001 ◽  
Vol 56 (6) ◽  
pp. 468-471
Author(s):  
G B Marks ◽  
J R Colquhoun ◽  
S T Girgis ◽  
M Hjelmroos Koski ◽  
A B A Treloar ◽  
...  
Keyword(s):  
Pollen Grains ◽  
Ground Level ◽  
Fold Increase ◽  
Underlying Mechanism ◽  
Detailed Examination ◽  
Asthma Exacerbations ◽  
Eastern Australia ◽  
The Difference ◽  
High Concentrations ◽  
Thunderstorm Outflow

BACKGROUNDA study was undertaken to assess the importance of thunderstorms as a cause of epidemics of asthma exacerbations and to investigate the underlying mechanism.METHODSA case control study was performed in six towns in south eastern Australia. Epidemic case days (n = 48) and a random sample of control days (n = 191) were identified by reference to the difference between the observed and expected number of emergency department attendances for asthma. The occurrence of thunderstorms, their associated outflows and cold fronts were ascertained, blind to case status, for each of these days. In addition, the relation of hourly pollen counts to automatic weather station data was examined in detail for the period around one severe epidemic of asthma exacerbations. The main outcome measure was the number of epidemics of asthma exacerbations.RESULTSThunderstorm outflows were detected on 33% of epidemic days and only 3% of control days (odds ratio 15.0, 95% confidence interval 6.0 to 37.6). The association was strongest in late spring and summer. Detailed examination of one severe epidemic showed that its onset coincided with the arrival of the thunderstorm outflow and a 4–12 fold increase in the ambient concentration of grass pollen grains.CONCLUSIONSThese findings are consistent with the hypothesis that some epidemics of exacerbations of asthma are caused by high concentrations of allergenic particles produced by an outflow of colder air, associated with the downdraught from a thunderstorm, sweeping up pollen grains and particles and then concentrating them in a shallow band of air at ground level. This is a common cause of exacerbations of asthma during the pollen season.

Sign in / Sign up

Export Citation Format

Share Document