Environmental Chemistry of Arsenic (Books in Soils, Plants, and the Environment)

406 Pages·2001·3.27 MB·English

by  William T. Frankenberger Jr

ISBN:0-8247-0676-5
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Preface
Arsenic-contaminatedsoils,sediments,andsludgesarethemajorsourcesofarse-
nic contamination of the food chain, surface water, ground water, and drinking
water. Arsenic is a known carcinogen and mutagen posing serious health risks
tohumansandanimals.Healtheffectsincludingcancersoftheskinandinternal
organs have been linked to chronic exposure to arsenic in drinking water.
The effect of arsenic on human health is an issue of global concern. A
large-scaleshiftinwaterresourceallocationfromsurfacewatertogroundwater
in West Bengal, India, and Bangladesh (tube well water) and the exposure of
local populations to ground water containing arsenic at concentrations of sev-
eral hundred µg/L have resulted in very extreme environmental health effects.
Spurredbyincreasingconcernoverexposuretolowlevelsofarsenicindrinking
water,theU.S.EnvironmentalProtectionAgency(EPA)hasproposedlowering
the maximum contaminant level (MCL) for arsenic from 50 to 5–10 µg/L.
Thisbookcontainscontributionsfromworld-renownedinternationalscien-
tistsontopicsthatincludetoxicityofarsenic,analyticalmethods fordetermina-
tionofarseniccompoundsintheenvironment,healthandriskexposureofarse-
nic,biogeochemicalcontrolsofarsenic,treatmentofarsenic-contaminatedwater,
and microbial transformations of arsenic that may be useful in bioremediation.
Therehavebeenmanynewexcitingdiscoveriesintheenvironmentalchem-
istryofarsenic.Chapter1tracesthesordidhistoryofarsenicfromancienttimes
torecenttimesanddiscussesitsmanifoldusesinhumantherapy,dailycommodi-
ties, pesticides, animal husbandry, and wars. Arsenic is still affecting our daily
lives,andmillionsofpeoplearebeingchronicallyexposedto elevatedlevelsof
arsenic from food, air, water, and soils with unknown long-term health conse-
quences.
Chapters2and3focusonthedetectionofarsenicandarseniccompounds
iii
iv Preface
intheenvironment.Newanalyticalmethodsandinstrumentsallowdetermination
oftraceandultra-traceconcentrationsofarsenicandarseniccompounds(Chapter
2). With detection of trace levels, the toxic reputation of arsenic might change
fromthatasalife-threateningelementtoanessentialelement.Chapter3covers
extensive characterization of environmental arsenic compounds including arse-
nic-containingmineralsandspecificspeciesfoundinbothterrestrialandmarine
environments. This chapter focuses on environmental compartments of arsenic
compounds including marine life, terrestrial fungi and lichens, plants, and ani-
mals.
Chapters4,5,and6coverhumanexposuretoarsenicingestion,inhalation,
anddermalabsorption.Metabolismofarsenicinthebodydependsonthechemi-
cal species of arsenic absorbed. Association of arsenic in human urine is the
mostsuitablebiomarkertoassessexposuretoarsenic.Riskcharacterizationand
bioavailability of arsenic upon soil ingestion is critically evaluated. Arsenic oc-
currence in the United States is compared to that in Taiwan for health implica-
tions.Factorsthatmayinterferewitharsenicremovalduringwatertreatment,as
wellassignificantdiurnalandseasonalvariationsinarsenicconcentrationinU.S.
surface water supplies, are thoroughly discussed.
Chapter 7 covers the biogeochemical control of arsenic occurrence and
mobilityinwatersystems.Arsenicconcentrationsarecomparedingroundwater
and surface water supplies. Redox control as well as dissolution, precipitation,
adsorption, and desorption are important parameters in the biogeochemistry of
arsenic. Arseniciscycledin soilsand natural watersbyphysical,chemical, and
microbiological processes (Chapter 8). A greater understanding of these pro-
cesses in arsenic cycling has allowed the development of suitable models for
predictingarsenicspeciation,bioavailability,andsubsequentriskexposure.Arse-
nicmayentertheenvironmentnaturallyfromarsenic-containingmineralsaswell
asfromnaturalwasteasherbicides orasinsecticides.Arsenicindrinkingwater
canberemovedbyavarietyoftreatmentprocesses.Chapter9focusesonarsenic
treatment by metal oxide adsorption, ion exchange and iron III coagulation–
microfiltration.
Many microorganisms are known for their ability to reduce, oxidize, and
methylate arsenic.Chapter 10coversthemoleculargeneticsofbacterialarsenic
resistance and enzymatic transformations of inorganic arsenic oxyanions. Inor-
ganicarsenicoxyanions,frequentlypresentasenvironmentalpollutants,arevery
toxic to most microorganisms. Many microbial strains possess genetic determi-
nants that confer resistance by encoding specific efflux pumps able to extrude
arsenic from the cell.
Chapter 11 covers the exciting discovery of respiratory reduction of arse-
nateby prokaryotes,includingseven newand highlydiverse species ofEubact-
eria and one new and one previously isolated species of Cremoarchae. Detailed
biochemicalandgeneticcharacterizationoftheenzymesinvolvedintheseorgan-
Preface v
isms are thoroughly discussed. Chapter 12 reveals a unique mode of arsenate
respiration by Chrysogenes arsenatis and Desulfomicrobium sp. str. Ben-RB.
Theseorganismshavespecificrespirationarsenatereductasesinvolvedinenergy
generation and have potential for removal of arsenic from potable water.
Anumberofbacteriahavetheabilitytooxidizearseniteincludinghetero-
trophs and at least three autotrophic bacteria (Chapters 13–15). Some hetero-
trophsare ableto usearsenite asan auxiliarysource ofenergy, but others seem
tooxidizearsenitetoarsenatemerelyasameansofdetoxificationsincearsenite
is more toxic than arsenate (Chapter 13). Oxidation of arsenite in freshwater
and sewage, soil and the marine environment as well as oxidation of As(III)-
containingmineralsareextensivelyreviewed.Chapter14providesnewinforma-
tiononthediscoveryofsixnewchemolithoautotrophicarsenite-oxidizingbacte-
ria isolated from gold mines from different regions of Australia demonstrating
thatenergyforgrowthcanbeconservedduringtheoxidationofarsenitetoarse-
nate.Chapter15discussestheoxidationofarsenitebyAlcaligenesfaecalis.The
arsenite oxoreductase was purified and characterized and found to effectively
catalyze the oxidation of arsenite to arsenate.
Chapter 16 focuses on the methylation and volatilization of arsenic. Bio-
methylation of arsenic results in formation of mono-, di- and trimethylarsine,
which are volatile gases. In developing a bioremediation strategy to clean the
environmentofarsenic,special attentionmustbepaidto thetoxicnatureofmi-
crobiallytransformedarseniccompounds.Thischaptercoverstheenvironmental
parametersthatpromotearsenicvolatilizationundernaturalandengineeredcon-
ditions.
Inrecentyears,wehaveseendynamicgrowthinunderstandingarsenicas
a result of the teamwork of a worldwide community of researchers working on
arsenicspeciation,transformations,transportkinetics,seasonalcycling,accumu-
lation, geochemistry, and toxicology. New developments in arsenic biological
andgeochemicalbehaviorwillengenderbetterunderstandingindevelopingsafe
levelsforconsumptionofwaterforhumansworldwide.Itisnowevidentthattotal
elemental concentrations of arsenic are not reliable indicators of environmental
toxicity.Extensiveeffortsshouldbedevotedtodevelopingarsenic-specificspeci-
ation and soil fractionation techniques. New remediation strategies have been
developed that combine biological, chemical, and physical remediation tech-
niques.
Thisimportantinformationiscompiledintoasingleresourcefordistribu-
tion among scientists, regulators, and the general public. This book will have a
worldwideimpactonthetreatmentofpotablewaterscontaminatedwitharsenic.
William T. Frankenberger, Jr.
Joan M. Macy
In Memoriam
This book is dedicated to Professor Joan M. Macy.
ProfessorJoanMarieMacy’s25yearscientificcareerwasnotableprimarily
forherabilitytoisolateandcharacterizeunusualbacteriaaswellasforhergifted
teaching.
SheobtainedherPh.D.in1974fromUniversityofCalifornia,Davis,under
the supervision of Professor W. Hungate, one of the pioneers in the study of
anaerobes. An Alexander von Humboldt fellowship made it possible for her to
go to Germany, where she worked as a postdoctoral fellow from 1974 to 1976
with Professor G. Gottschalk at the Institut fu¨r Mikrobiologie, Georg-August-
Universita¨t,Go¨ttingenandcontinuedworkingwithanaerobes.WhileinGermany
shedevelopedaninterestinGermanculture—literatureandmusicinparticular.
She was awarded a second Fulbright in 1985 and returned to Germany to work
with Professor R. Thauer at FB Mikrobiologie, Biologie, Philips Universita¨t,
Marburg.
Aftera1990–1991sabbaticalatMonashUniversityinMelbourne,in1995
sheacceptedthe appointmentasChair ofMicrobiology atLaTrobeUniversity,
Melbourne, where she remained until her untimely death in 2000.
Hermostrecentscientificcontributionswereintheareasofbacterialsele-
nium and arsenic metabolism. Her interest in bioremediation began with sele-
nium-contaminated water found in the San Joaquin Valley in California, from
which she isolated the first bacterium able to respire with selenate (reducing it
to selenite and then to elemental selenium) using acetate as the electron donor/
carbon source. This organism was found to represent a new genus and named
Thaueraselenatis.Shestudiedtheorganismextensivelyforthepurposeofsele-
nium bioremediation. This involved the design and implementation of lab-scale
and then pilot-scale reactors.
vii
viii InMemoriam
Morerecently,shebecameinterestedintheproblemofarseniccontamina-
tion andisolatedthefirstbacteriumabletousearsenateastheterminalelectron
acceptor and acetate as the electron donor. This organism, a strict anaerobe, re-
duces arsenate to arsenite. It too was found to represent a new genus and was
namedChrysiogenesarsenatis(Chrysiogenes(cid:1)sprungfromagoldmine;arse-
natis(cid:1)ofarsenate).Morerecently,thisorganismwasdesignatedthefirstrepre-
sentative of a new phylum of the Bacteria. A separate group of novel bacteria,
which oxidize arsenite to arsenate, were isolated from gold mines in Australia.
Shehadhopedthattogetherthesebacteriawouldprovesuitableforuseinpurify-
ingarsenic-contaminatedwasteanddrinkingwater.Thisworkledhertopresent
a paper at the International Conference on Arsenic held in Dhaka, Bangladesh,
in 1998.
At the time of her death Professor Macy was at the forefront of her field
and was just starting to receive the accolades that she well deserved.
Contents
Preface iii
In Memoriam vii
Contributors xi
1. Arsenic Poisoning Through the Ages 1
Jerome O. Nriagu
2. Analytical Methods for the Determination of Arsenic and
Arsenic Compounds in the Environment 27
Walter Goessler and Doris Kuehnelt
3. Arsenic Compounds in the Environment 51
Kevin A. Francesconi and Doris Kuehnelt
4. Arsenic Speciation in the Environment and Humans 95
X. Chris Le
5. Bioavailability and Risk of Arsenic Exposure by the Soil
Ingestion Pathway 117
Nicholas T. Basta, Robin R. Rodriguez, and Stan W.
Casteel
6. Aspects of Arsenic Chemistry in Relation to Occurrence,
Health, and Treatment 141
Laurie S. McNeill, Hsiao-wen Chen, and Marc Edwards
ix