Suchergebnisse

AbstractPhytoremediation is an emerging technique that can be used to economically remediate sites contaminated with
trace elements and/or man‐made organic contaminants. This technique was used on Pearl Harbor (Oahu,
Hawaii) dredged material (PHDM) containing polycyclic aromatic hydrocarbons (PAHs) and
some heavy metals. The dredged material was first amended with a high‐calcium soil (Waialua
Mollisol) and a biosolids‐based compost at different proportions to yield varying salinity levels. A
mixture that yielded an electrical conductivity (EC, a measure of salinity) of the saturated paste
extract of 15 to 20 dS/m was identified and used to evaluate the salt tolerance of five plant species. Relative
germination and one‐month‐old biomass indicated that common bermuda grass (Cynodon
dactylon), seashore paspalum (Paspalum vaginatum), beach pea
(Vigna marina), and cow pea (Vigna unguiculata) can produce
at least 40 percent of biomass of the control at an EC of approximately 18 dS/m, suggesting the four plants are
relatively salt tolerant. In contrast, Desmodium intortum either did not germinate or died within
two weeks after germination at the same salinity level. A subsequent greenhouse experiment, using mixtures of the
PHDM (0 or 25 percent dry weight), organic amendments (10 percent leucaena green manure or
biosolids‐based compost), and a Mollisol (65 or 90 percent dry weight) in 6‐liter pots
containing 4 kilograms of material yielded the following results: (1) a combination of transplanted
seashore paspalum, seeded bermuda grass, and seeded beach pea was effective in taking up sodium (Na),
thereby reducing salinity and making the medium more amenable to diversified microbes and plants, which may be
effective PAH degraders; (2) total PAH concentration was reduced by about 30 percent after three
months of active plant growth, but degradation of individual PAH members varied significantly, however;
(3) leguminous green manure, as a soil amendment, was more effective than compost for use in bio‐
and/or phyto‐remediations; and (4) soil amendments, when applicable, could supplement
living plants in reducing organic contaminants, such as PAHs. © 2003 Wiley Periodicals, Inc. Reprinted from
Remediation Volume 12, Number 4.