Toxicity and Bioavailability of Heavy Metals and Hydrocarbons in Mangrove Wetlands and Their Remediation - Environmental Contamination: Health Risks and Ecological Restoration - page 377

A. corniculatum

50
40

30
20
10
0

a

abab

N S

N S

b

b NS

1 3 5 7

B. gymnorrhiza

0
200
400
600
800

a

50
40

b b b b

30
20
10
0

NS

NS NS

1 3 5 7

R. stylosa

50
40

a

a

30
20
10
0

b

b b

b a NS

b

b

b b

b b b b

1 3 5 7

FIGURE 17.2
Spatial.patterns.of.ROL.along.the.lateral.roots.of.three.mangrove.seedlings.receiving.differ-
ent.concentrations.of.Zn.(mg/kg).under.greenhouse.conditions..Different.letters.in.the.same.
group.of.bars.indicate.signiicant.differences.at.P.≤.0.05.as.determined.by.LSD..NS,.not.signii-
cant..(Data.used.for.plotting.are.from.Cheng,.H..et.al.,. Environ. Pollut .,.158,.1189,.2010.)

for. B. gymnorrhiza ,.but.toward.the.root.tip.for. E. agallocha ..The.relationship.
between. ROL. and. Fe.plaque. was. not. signiicant,. suggesting. that. although.
ROL. had. a. signiicant. contribution. to. Fe. plaque. formation,. too. much. Fe.
plaque.would.serve.as.a.“barrier”.to.ROL..Actually,.Fe.plaque.not.only.acts.
as. a. “barrier”. to. ROL. but. also. reduces. the. plant. uptake. of. heavy. metals,.
including.Zn,.Cd,.As,.Ni,.Mn,.Pb,.and.Cu,.and.nutrients.(such.as.P).through.
immobilization.and.coprecipitation.(Taylor.and.Crowder.1983,.Christensen.
and. Sand-Jensen. 1998,. Ye. et. al.. 1998,. 2003a,. Liu. et. al.. 2004,. Machado. et. al..
2005,.Liang.et.al..2006)..The.relationships.among.ROL,.Fe.plaque.formation,.
and.immobilization.of.heavy.metals.are.shown.in.Figure.17.3..The.Fe.plaque.