Detection of petroleum contamination in river sediments from Quebec City region using GC–IRMS

Although widely detected in marine ecosystems, microplastic pollution has only recently been documented in freshwater environments, almost exclusively in surface waters. Here, we report microplastics (polyethylene microbeads, 0.40–2.16 mm diameter) in the sediments of the St. Lawrence River. We sampled 10 freshwater sites along a 320 km section from Lake St. Francis to Québec City by passing sediment collected from a benthic grab through a 500 μm sieve. Microbeads were discovered throughout this section, and their abundances varied by four orders of magnitude across sites. Median and mean (±1 SE) densities across sites were 52 microbeads·m−2 and 13 832 (±13 677) microbeads·m−2, respectively. The highest site density was 1.4 × 105 microbeads·m−2 (or 103 microbeads·L−1), which is similar in magnitude to microplastic concentrations found in the world’s most contaminated marine sediments. Mean diameter of microbeads was smaller at sites receiving municipal or industrial effluent (0.70 ± 0.01 mm) than at non-effluent sites (0.98 ± 0.01 mm), perhaps suggesting differential origins. Given the prevalence and locally high densities of microplastics in St. Lawrence River sediments, their ingestion by benthivorous fishes and macroinvertebrates warrants investigation.

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INFLUENCE OF TIME OF EMERGENCE AND PLANT DENSITY ON GROWTH OF HEMP-NETTLE (Galeopsis tetrahit)

Canadian Journal of Plant Science ◽

10.4141/cjps89-019 ◽

1989 ◽

Vol 69 (1) ◽

pp. 171-183 ◽

Cited By ~ 3

Author(s):

ANNE LÉGÈRE ◽

JEAN-MARC DESCHÊNES

Keyword(s):

Plant Density ◽

Plant Biomass ◽

Biomass Accumulation ◽

Quebec City ◽

Total Biomass ◽

City Region ◽

Higher Plant ◽

Peak Period ◽

Plant Densities ◽

Broadleaf Species

The effects of time of emergence and plant density on hemp-nettle growth (Galeopsis tetrahit) were measured in natural field populations from the Québec City region and in a greenhouse experiment. In the field, more than 80% of the plants emerged during a peak period of about 2 wk in early May. Few hemp-nettle plants emerged after this peak period. Late-emerging plants produced relatively little biomass compared to plants that had emerged during the early emergence flush. Total biomass accumulation increased with density on three out of four sites. Stands from the lowest density (80 plants m−2) generally produced less biomass than stands of higher plant densities. Average plant biomass production decreased with increasing density. Plants from low density stands displayed a bushy profile compared to the etiolated, single-stemmed plants from high density stands. Mature hemp-nettle stands did not develop strong hierarchical population structures such as found for other annual broadleaf species. Hemp-nettle plants within a stand were distributed rather evenly over a number of height classes. A large proportion of the total biomass was produced by a relatively considerable number of plants 45–59 cm in height rather than by a few dominating individuals.Key words: Hemp-nettle, Galeopsis tetrahit, weed populations, emergence pattern, population density, population structure

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Parasite Contamination of Sand and Soil from Daycare Sandboxes and Play Areas

Canadian Journal of Infectious Diseases ◽

10.1155/1994/786090 ◽

1994 ◽

Vol 5 (1) ◽

pp. 17-20 ◽

Cited By ~ 2

Author(s):

Theresa W Gyorkos ◽

Evelyne Kokoskin-Nelson ◽

J Dick MacLean ◽

Julio C Soto

Keyword(s):

Health Risk ◽

Practice Guidelines ◽

Environmental Conditions ◽

Surface Soil ◽

Human Infection ◽

Quebec City ◽

Helminth Parasites ◽

City Region ◽

Surface Sand

Objectives: To determine if there was parasite contamination in the sand and soil in daycare sandboxes and play areas, with the goal of developing practice guidelines for their management.Methods: One hundred samples of sand and soil from 10 daycare centres in different regions of the province of Quebec, collected between April 22 and May 6, 1991, were examined.Results: Toxocara eggs were found in both surface and subsurface sand from two Montreal centres and co-occurred withAscarisspecies (surface sand) in one centre and with hookworm (surface soil) in the second. Hookworm eggs were also recovered from one centre in the Quebec City region.Conclusions: These results document the presence of potentially pathogenic helminth parasites in the daycare environment. Evidence from the literature regarding the health risk to children is insufficient and highlights the need for further research into the assessment of the risk of human infection and morbidity, the viability of these parasites under different environmental conditions and practical issues related to the management of sand and soil.

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