Amaranth greens can clean toxic soil, but also absorb it
Galahitigama H, Sandamali WHP, Jayarathne DGDDS, Sugathadasa SGAR, Weerasekara WMPH
Phytoremediation
If you're growing amaranth greens in a city plot, near an old industrial lot, or along a roadside, the same traits that make it a hardy, fast-growing green also make it exceptionally good at soaking up whatever heavy metals are lurking in the soil.
Amaranth, the leafy green also used as a grain crop, grows fast and tolerates a lot of environmental stress, including soil polluted with metals like lead, cadmium, and chromium. Scientists reviewing decades of studies found the plant actively pulls these metals out of soil through its roots and stores them in its tissues, which is great for cleaning up contaminated land but risky if that same plant ends up on someone's dinner plate. The review calls for better guidelines on when amaranth is safe to eat versus when it should be used strictly as a pollution-fighting tool.
Key Findings
Amaranthus species can extract or stabilize at least nine trace metal(loid)s: cadmium, lead, copper, zinc, chromium, nickel, barium, cesium, and others
Metal tolerance and accumulation are driven by transporter proteins, chelation, vacuolar storage, antioxidant defenses, and interactions with soil microbes
Effectiveness varies widely by species, contaminant type, soil conditions, and whether agronomic or microbial enhancement strategies are used
chevron_right Technical Summary
Amaranth plants, including species grown as leafy greens, can pull heavy metals like lead and cadmium out of contaminated soil, but the same fast growth that makes them good cleanup plants also means they can accumulate toxins in leaves people eat.
Abstract Preview
Original paper
Exploring the phytoremediation capacity of Amaranthus species in trace metal(loid)-impacted terrestrial environments.
Environmental contamination by trace metal(loid)s threatens human health and ecological sustainability. Plants possess natural mechanisms to mitigate contaminated environments. This review synthesi...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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Amaranthus is a genus of plants commonly known as amaranths. Some species are known by variants of the common name "pigweed". Some members are annual and others are perennial. The plant can grow from 1 to 2.5 metres tall with a succulent, hollow stem. Parts of the plant vary from green to reddish...