Wednesday, June 30, 2010

Sugar cane : arsenic :: love : marriage

Whew! Deriving today's title required summoning dusty recollections of analogies from the recesses of my mind. Anyway, many locals know one of Hilo's worst-kept secrets: that Hilo Bay and environs are polluted with arsenic, a by-product of the Canec industry. Canec is a building material, made only in Hawaii, that was popular and cheap, and made from sugar cane stalks treated with arsenic.

From 1932 to 1963 the Hawaiian Cane Products plant in Hilo manufactured Canec from bagasse, the fiber left after sugar cane stalks are crushed for their juices. The process included treating Canec with arsenic to deter insects and minimize mildew. Although Canec hasn't been manufactured in decades, contamination survived. At least one study reported arsenic concentrations in the sediments of Hilo Bay as high as 6370 ppm, approximately 34 times higher than anywhere else in the state.

A few years ago the plan was to cover shoreline soils with three feet of fresh soil. I'm not quite sure what that would--or did--accomplish, since the proposed fix seemed as ineffective as the discredited "solution to pollution is dilution." Nevertheless, as recently as late April, the Hawaii Tribune Herald reported that work was continuing on efforts to cover up contaminated soil on the site of the future Target and Safeway stores in Hilo, where high levels of arsenic, dioxins and petroleum compounds were found.

So, if covering up a heavy metals problem, well, only covers it, what's the alternative? Yup, you guessed it. Vetiver!

Research conducted at least since the mid 1980s confirms that Vetiver tolerates a wide range of soil acidity, alkalinity, salinity, sodicity, and elevated levels of Aluminium, Manganese, and heavy metals such as Arsenic, Cadmium, Chromium, Nickel, Lead, Zinc, Mercury, Selenium and Copper in the soil. (Truong, P., et al).

It also absorbs large quantities of heavy metals from industrial waste and, in the process, protects ground water from contamination, claim a duo of researchers at India's Kerala University.

In a paper presented at the Kerala Environment Congress 2010, concluded on Saturday, researchers D.S. Jaya and G. Dhanya report that the penetrating roots of fast-growing
Vetiver can effectively remove hazardous heavy metals from industrial effluents.

Since industrial waste poses a great threat to the environment, Vetiver will become a great boon, say the researchers, who are the faculty members of the Department of Environment Science of Kerala University. Vetiver planted around industrial firms that flush out metal-rich waste water will remove the metals from the water. "Thus the soil and ground water of the region will be protected without being degraded," Jaya said.

Large numbers of Vetiver plants could be grown in artificial wetlands around factories and industrial units and thus protect the environment, she said, adding that technologies were also available to recover the metals from the plant material.

"Another interesting fact is that the plants have shown different efficiency for absorbing different metals. Good results are shown for zinc, lead and cadmium," Jaya said.

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