A schematic of the mechanism that explains why shallow lakes are more sensitive to shallow water pollution with Arsenic than deep lakes.
A schematic of the mechanism that explains why shallow lakes are more sensitive to shallow water pollution with Arsenic than deep lakes. During the warm season, a warmer layer develops on top of a cold layer. The cold layer becomes depleted of oxygen as it is cutoff from the atmosphere by the warm layer. This leads to the mobilization of Arsenic. During episodic mixing events that can occur under night-time cooling of the upper layer, the Arsenic is transported to the lake surface where it is taken up by the organisms living there. Credit: Fung et al. [2022], Figure 8
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Water Resources Research

Lakes in urbanized areas accumulate arsenic in their bottom sediments as a result of human activities, such as mining, smelting, and the application of arsenic-containing pesticides. If this arsenic ends up in the water column close to the surface, it can endanger lake ecosystems and human health. Shallow lakes are more susceptible to high arsenic concentrations in their waters than deep lakes, but the cause of this was unknown.

Fung et al. [2022] found the explanation by using a combination of dedicated observations of lake turbulence intensity, temperature, and concentrations of dissolved oxygen and arsenic. Understanding this mechanism will be highly beneficial in guiding measures to keep arsenic concentrations in shallow lakes at bay.

Citation: Fung, S. R., Hull, E. A., Burkart, K., Gawel, J. E., Horner-Devine, A. R., & Neumann, R. B. (2022). Seasonal patterns of mixing and arsenic distribution in a shallow urban lake. Water Resources Research, 58, e2022WR032564. https://doi.org/10.1029/2022WR032564

—Marc F. P. Bierkens, Editor, Water Resources Research

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