Environmental Engineering Reference
In-Depth Information
or.higher.in.the.same.tissue.(Hemphill.1972,.Marschner.1995)..The.highest.
quantity.of.copper.can.be.found.in.seeds,.nuts,.and.legumes.of.plants,.with.
some.nuts.such.as.cashews.and.coconuts.reaching.levels.of.30.μg/g.or.more.
Copper.deicient.plants.can.display.a.wide.variety.of.symptoms.depend-
ing. on. the. plant. species. and. developmental. stage.. Symptoms. consist. of.
decreased. growth. rate,. distortion. or. whitening. of. young. leaves,. damage.
to. the. apical. meristem,. as. well. as. a. decrease. in. fruit. formation. (Childers.
et.al..1995,.Marschner.1995)..Secondary.effects.of.copper.deiciency.can.be.a.
decrease.in.cell.wall.formation.and.ligniication.in.several.tissues,.including.
xylem.tissue.which.would.result.in.insuficient.water.transport.(Marschner.
1995)..Due.to.the.elevated.levels.of.copper.found.in.reproductive.tissue,.dei-
ciency.has.a.severe.effect.on.pollen.development.and.viability,.fruit.and.seed.
production,. in. addition. to. embryo. development. and. seed. viability.. High.
nitrogen. concentrations. in. soils. can. induce. copper. deiciency. in. plants. by.
decreasing.copper.mobility.and.availability.(Marschner.1995).
Copper. toxicity. thresholds. vary. greatly. between. species. of. plants. and.
affect.tissues.differently.depending.on.metabolic.requirements..Excess.cop-
per. concentrations. in. the. soil. tend. to. decrease. root. growth. before. shoot.
growth. due. to. preferential. copper. accumulation. in. that. organ. (Marschner.
1995)..The.most.common.general.symptom.of.toxicity.is.chlorosis.of.vegeta-
tive.tissue..Increased.formation.of.free.radicals.resulting.in.oxidative.stress.
can.occur.when.high.amounts.of.Cu,.Cd,.Pb,.or.Al.are.observed.at.a.cellular.
level. (Pessarakli. 2005).. At. a. molecular. level,. photosynthesis. is. affected. by.
damage. to. thylakoid.membranes. resulting.in. changes. to.chloroplast. ultra-
structure,.inhibition.of.electron.transport.between.photosystem.II.(PSII).and.
photosystem.I.(PSI),.and.impairment.of.carboxylase.and.oxygenase.activities.
of.RUBISCO.(Pessarakli.2005)..Copper.toxicity.can.also.reduce.iron.up.take,.
even.to.the.point.of.deiciency,.depending.on.the.form.of.iron.available.in.the.
soil.(Marschner.1995).
Requirements for Metabolism
The. three. most. abundant. trace. elements. in. biochemical. systems. are.
iron,. zinc,. and. copper. (Bhattacharya. 2005).. Since. several. proteins. and.
enzymes. require. copper. for. proper. function,. copper. is. essential. for. sur-
vival.of.most.organisms.(Linder.and.Goode.1991)..Copper.containing.pro-
teins. have. three. major. functions:. dioxygen. transport,. catalytic,. or. copper.
transport/sequestration.(Bhattacharya.2005)..Photosynthetic.organisms.do.
not.contain.copper.proteins.that.function.in.dioxygen.transport..However,.
one.example.of.such.a.protein.is.hemocyanin.that.can.be.found.in.mollusks,.
arthropods,. and. annelids.. Hemocyanin. is. an. exceptionally. large. protein.
(4500-9000.kDa). that. is. oxygenated. in. the. gills. of. mollusks. and. transfers.
oxygen.to.tissues.throughout.the.organism.(Bhattacharya.2005).
Copper.proteins.that.have.catalytic.functions.include.oxidation,.electron.
transfer,. and. superoxide. dismutation.. Laccase. and. ascorbate. oxidase. are.
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