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This is calling out for a large microbiome study: Salt from icy roads is contaminating North America’s lakes

It seems to me that this is calling out for some large scale comparative microbial community study:

Salt from icy roads is contaminating North America’s lakes – The Washington Post

Basically, there is evidence that lakes throughout North America have seen a big increase in salt levels connected to salt used to try and deal with ice on roads.

From the Post:

Of 371 lakes reviewed in the new study, 44 percent showed signs of long-term salinization.Extrapolating that finding for all of North America, at least 7,770 lakes are at risk of elevated salt levels — a likely underestimate, the researchers said.

This article is based on a new paper in PNAS: Salting our freshwater lakes by Hilary Dugan et al.

From their paper:

Significance

In lakes, chloride is a relatively benign ion at low concentrations but begins to have ecological impacts as concentrations rise into the 100s and 1,000s of mg L−1. In this study, we investigate long-term chloride trends in 371 freshwater lakes in North America. We find that in Midwest and Northeast North America, most urban lakes and rural lakes that are surrounded by >1% impervious land cover show increasing chloride trends. Expanding on this finding, thousands of lakes in these regions are at risk of long-term salinization. Keeping lakes “fresh” is critically important for protecting the ecosystem services freshwater lakes provide, such as drinking water, fisheries, recreation, irrigation, and aquatic habitat.

Abstract
The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L−1), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue.

Although they do not really discuss this – it seems to me that there could be some very interesting microbial ecology to be done on these lakes.  We know that the microbial communities in various bodies of water is related to salinity levels (e.g., see this or this) and microbial data might be of interest or of use here. This would be an interesting case of the interaction between the built environment (in this case, roads) and global microbial communities. I wonder if anyone is working on this.

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