Hydrogeologists at the University of Texas at Austin have found that the Mississippi River network’s natural filtering process is close to full capacity, which means that the network’s ability to filter out nitrates as water passes through sediment along its banks may be inadequate to deal with the high levels of the contaminant that find their way into the network’s waterways. Their research, which appears in the journal Nature Geoscience, suggests that the system is being overwhelmed. (phys.org)

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