Metallic elements and oxides and their relevance to Laurentian Great Lakes geochemistry

Abstract

The Laurentian Great Lakes are the most studied system in lake geochemistry and have well-preserved chronological profiles. Metals play numerous critical roles in natural and anthropogenic characteristics of lake ecosystems, so patterns in the historical records of metals from sedimentary cores provide important information about environmental baselines and human impacts. Relevant studies of Great Lakes geochemistry are listed, and we follow with encyclopedic descriptions of metals and their oxides in the lakes. These descriptions include likely natural and anthropogenic sources of elements, their known history from previous paleoecological studies, and their status as potential contaminants of concern. Despite the well-studied geology of the Great Lakes catchment, sourcing elements was sometimes difficult due to materials often being moved long distances by glaciation and the global prevalence of atmospheric pollutants. We summarized available information on metals and their roles as geochemical indicators in the Great Lakes.

Low cobalt limits cyanobacteria heterocyst frequency in culture but potential for cobalt limitation of frequency in nitrogen-limited surface waters is unclear

“…The majority of the total Co concentrations in Canadian High Arctic freshwaters were less than the relatively high detection limit of 17 nmol L -1 but the proportion in the subnanomolar range relevant to Co limitation of heterocyst frequency is unknown. Low Co in Arctic regions is expected because of low weathering rates caused by long periods of freezing temperatures and low precipitation (Statistics Canada, 2017) and the absence of mining, industrial activities and urbanization in most areas (Aliff et al, 2020). However, Co content in bedrock and overburden can vary regionally which would affect aquatic concentrations.…”

The Laurentian Great Lakes: A Biogeochemical Test Bed

“…A comprehensive summary of the extensive literature on the geochemistry of metallic elements in the Great Lakes (Aliff et al 2020) shows how humans have directly altered trace metal cycling, especially through mining. Trace metal (Cu, Cd, Pb, Ni) concentrations from the sediments of the western basin of Lake Erie track overall level of anthropogenic perturbations, with a gradual increase in metal in sediments starting in 1880, a rapid rise in concentrations between 1950 and 1970, and a gradual and still incomplete return to lower levels thereafter (Yuan et 2015).…”