Spatial Variations in Particle Size and Magnetite Concentration on Cedar Beach:Implications for Grain-Sorting Processes,Western Lake Erie,Canada

This study examined spatial variations in the concentration,grain size and heavy mineral assemblages on Cedar Beach（Lake Erie,Canada）.Magnetic studies of heavy mineral-enriched,dark-reddish sands present on the beach showed that magnetite（～150μm） is the dominant magnetic mineral.Surficial magnetic susceptibility values defined three zones：a lakeward region close to the water line（Zone 1）,the upper swash zone（Zone 2） and the region landwards of the upper swash zone （Zone 3）.Zone 2 showed the highest bulk and mass susceptibility（κ,χ） and the highest mass percentage of smaller grain-size（250μm） fractions in the bulk sand sample.Susceptibility（i.e.κandχ） values decreased and grain size coarsened from Zone 2 lakewards（into Zone 1） and landwards （into Zone 3）,and correlated with the distribution of the heavy mineral assemblage,most probably reflecting preferential separation of large,less dense particles by waves and currents both along and across the beach.The eroded western section of Cedar Beach showed much higher concentrations of heavy minerals including magnetite,and finer sand grain sizes than the accreting eastern section, suggesting that magnetic techniques could be used as a rapid,cost-effective way of examining erosion along sensitive coastline areas.

St Lawrence Seaway: Eastern Great Lakes, the Niagara River and Welland Canal Replacement, Maintenance and Protection

The Eastern Great Lakes region covers 51,000 square km of land, and is home to 15 million people. This region is rich in natural resources, industry and agriculture, and forms the heartland of both Canada and the United States. The development of this region has a history that is closely tied to waterways, and the development of canals that promoted growth and prosperity. The St. Lawrence Seaway connects Western and Eastern Great Lakes to the St Lawrence River and the Gulf of Saint Lawrence. The New York State Canal and the St. Lawrence Seaway were linked by the Oswego canal and provided a shorter route for cargo via barges to New York City. The New York State (NYS) Barge Canal and the St. Lawrence Seaway provided pathways for the settlement of the Eastern Great Lakes. Lake Erie drains into Lake Ontario via the Niagara River but the river was not navigable due to the obstacles of Niagara Falls and the Niagara Escarpment. Until the 1820s ships could not travel into Lake Erie. It was not possible to engineer a bypass of Niagara Falls with a series of locks due to the 100 m high Niagara escarpment. This escarpment obstacle to Niagara River navigation was overcome in 1829 with the completion of the first of four Welland Canals with locks 40 kilometers west of the Niagara River through the glacial till and alluvium that overlays the Niagara Escarpment. This permitted ocean going ships to enter Lake Erie and to continue on to Lake Michigan, Lake Huron and Lake Superior. The Eastern Great Lake shorelines, river banks and canals are actively eroding as a consequence of high surface water levels and flooding. The settlement of millions of people into the Eastern Great Lakes via the NYS Barge Canal and St. Lawrence Seaway migration pathways have created environmental and natural resource risks and challenges. These challenges and risks include deterioration of the Fourth Welland Canal and the need to replace it with the Fifth Welland Canal, industrial and urban wastewater disposal, shoreline, river bank and canal erosion as results of high water levels, the building of structures on the shoreline banks, invasive species and flooding.

Effectiveness of a fixed-depth sensor deployed from a buoy to estimate water-column cyanobacterial biomass depends on wind speed

Water quality sondes have the advantage of containing multiple sensors,extended deployment times,high temporal resolution,and telecommunication with stakeholder accessible data portals.However,sondes that are part of buoy deployments often suffer from typically being fixed at one depth.Because water treatment plants are interested in water quality at a depth of the water intake and other stakeholders(ex.boaters and swimmers)are interested in the surface,we examined whether a fixed depth of approximately 1 m could cause over-or under-estimation of cyanobacterial biomass.We sampled the vertical distribution of cyanobacteria adjacent to a water quality sonde buoy in the western basin of Lake Erie during the summers of 2015–2017.A comparison of buoy cyanobacteria RFU(Relative Fluorescence Unit)at 1 m to cyanobacteria chlorophyll a(chla)measured throughout the water column showed occurrences when the buoy both under and overestimated the cyanobacteria chl a at specific depths.Largest differences between buoy measurements and at-depth grab samples occurred during low wind speeds(<4.5 m/sec)because low winds allowed cyanobacteria to accumulate at the surface above the buoy’s sonde.Higher wind speeds(>4.5 m/sec)resulted in better agreement between the buoy and at-depth measurements.Averaging wind speeds 12 hr before sample collection decreased the difference between the buoy and at-depth samples for high wind speeds but not low speeds.We suggest that sondes should be placed at a depth of interest for the appropriate stakeholder group or deploy sondes with the ability to sample at various depths.