BAGUIO CITY, Philippines??KANGKONG? (RIVER spinach) and ?gabi? (taro) are staple household vegetables often consumed by poor Filipinos or fed to backyard animals.

But these crops could be the solutions to mine river pollution that has tainted the mining industry for more than a century.

This year?s National Mine Safety and Environment Conference tackled climate change on Friday by presenting test cases of wetlands that have absorbed toxic minerals from waters discharged by the mines.

Rachel James, environmental consultant of the Canadian-led TVI Resource Development Philippines Inc., shared the results of an experiment that tried to determine how much mineral particles in mine waste water could be absorbed by the roots and shoots of seven plant species. TVI operates a mining operation in Zamboanga del Norte.

The wetland vegetation, which TVI harnessed at their Canatuan sulfide mineral deposits in Siocon town, includes water lily, ?tambo? (reed), water hyacinth, Vetiver grass and a local plant that James identified only as ?bugong.?

These plants form the first stage of a three-level cleansing process that requires two more sets of chemical treatments for run-off mine water.

Jesus Castillo, mill manager of the Lepanto Consolidated Mining Co. (LCMC), said polluted mine water has become a threat to their operations because of rising treatment costs.

Castillo said the reddish tint discharged with run off mine water would provoke hostility once the waste water invades the river used by outlying communities.

LCMC consultants said the acidity detected in the water discharged from the mines was supposed to be temporary, ?but experience told a different story,? Castillo said.

Castillo said LCMC used a combination of ?copper cementation? (a technique for obtaining copper lost in mine waters) and heavy metal precipitation to reduce at extreme low levels the residue of particulates of cadmium, copper, lead, nickel or silver in the discharged water.

It was James? experiments with plants that caught the attention of participants.

Her list drew amusement and skepticism from mining engineers.

Eliza Laudencia, a geologist, pointed out that gabi and kangkong, valued highly by low-income and neighboring communities, could end up harvesting toxic crops.

James said the wetland vegetation is ?toxic to humans and other living species,? compelling firms that use this process to isolate these mine wetland systems from populated areas.

It is the grass species which proved to have better mineral absorption capacities compared to the vegetables, James said, based on samples collected on Sept. 18 and Oct. 30.

She said vegetation would not remove all of the minerals discharged into mine water and must undergo a series of treatments.