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Integrated acidification study and survey on acid rain impacts
in China
Soil and soilwater interactions
The Environmental Chemistry groupDepartment of ChemistryUniversety of Oslo, Norway
SteppingstonesSteppingstones inin our our Cooperation withCooperation with ChinaChina
19881988:: Cooperation with Cooperation with ResearchResearch center forcenter for EcoEco--Environmental SciencesEnvironmental Sciences, CAS, CAS19921992: Catchment: Catchment studies withstudies withGuizhou Institute ofGuizhou Institute of EnvironmentalEnvironmental Science Science &&Chongqing Inst. ofChongqing Inst. of EnvironEnviron. Science and. Science and MonitoringMonitoring19951995:: Collaboration agreement betweenCollaboration agreement betweenThe Norwegian ministry of environment The Norwegian ministry of environment andand SEPASEPA19961996: PIAC: PIAC fundedfunded by by Norwegian Agency for Development CoNorwegian Agency for Development Co--operationoperation (NORAD) (NORAD) and theand the World BankWorld Bank--ASTENASTEN19961996: PIAC: PIAC cooperation withcooperation with SEPA SEPA && CREASCREAS19971997: PIAC: PIAC cooperation withcooperation with South China Institute ofSouth China Institute of BotanyBotany, CAS, CAS
PIACPIACPlanningPlanning of anof an Integrated ACidificationIntegrated ACidification study study
andand surveysurvey onon acid rain impactsacid rain impacts in Chinain ChinaNorwegianNorwegian participantsparticipants::
In NorwayIn Norway: : Norwegian Institute of InternationalNorwegian Institute of International AffairsAffairsNorwegian Institute for AirNorwegian Institute for Air ResearchResearchNorwegian Institute forNorwegian Institute for Forest ResearchForest ResearchThe Norwegian foundation The Norwegian foundation forfor naturenature andand cultural heritage researchcultural heritage researchNorwegian Institute for WaterNorwegian Institute for Water ResearchResearchUniversity of OsloUniversity of Oslo
The PIACThe PIAC projectprojectEstablish contacts Obtain an overview Evaluate needsSelection of sites
WhyWhy AlAl leaching mechanismsleaching mechanismsare important to understandare important to understand
Al isAl isMobilisedMobilised inin acidification processesacidification processesToxicToxic toto plantsplants andand aquaticaquatic faunafauna
ToTo predict future effectspredict future effects ofof acidification acidification we mustwe must bebe ableable toto predictpredict futurefuture AlAl--concentrationsconcentrations
UnderUnder variousvarious anthropogenicanthropogenic deposition scenariosdeposition scenariosIn differentIn different environmentsenvironments
OverviewOverview (After(After BergrenBergren && MulderMulder, 1995), 1995)
Al in primary minerals
Al in secondarymineral phases
Al adsorbedby SOM andexchangeable
Adsorbed Al(OH)3and Al in secondary minerals
Al3+ (aq)
Al(OH)2+Al(OH)2 +
Al(OH)F+
AlSO4+ AlF2+AlF
2 +
Slowly Slowly reactingreactingsolidsolid phasesphases
Rapidly Rapidly reactingreactingsolidsolid phasesphases
1. Gibbsite1. GibbsiteSolubilitySolubility && IonexchangeIonexchange
Al(OH)Al(OH)3 3 (S)(S) + 3H+ 3H++ = Al= Al3+3+ + H+ H22OO
MayMay bebe expressedexpressed as:as:
pAl = 3pH +pAl = 3pH + pKpK
Reported values varymore than afactor 1000
Most reported valuesfor soilwater are
less than 3
2. 2. IonIon exchangeexchangewithwith base cationsbase cations
E.g. CaE.g. Ca2+2+::2Al2Al3+3+ + 3CaX = 3Ca+ 3CaX = 3Ca2+2+ + 2AlX+ 2AlX
TheGaines Thomas constant
is difficoult toestimate
3.3. Jurbanite Jurbanite SolubilitySolubility/Co/Co--adsorptionadsorption
Al(OH)SOAl(OH)SO4 4 (S)(S) + H+ H++ = Al= Al3+3+ + + SOSO4422-- + H+ H22OO
MayMay bebe expressedexpressed as:as:
pAl = pH pAl = pH -- pSOpSO4 4 ++ pKpKsp sp
ChallengeChallengeTheThe relationships betweenrelationships between
soilwater chemical parameters as pH, pSOsoilwater chemical parameters as pH, pSO44 and pAland pAlexhibitexhibit largelarge spatial variationspatial variation
TheThe questquest is tois to findfind::A simpleA simple soilsoil chemical parameterchemical parameterthatthat,, together with keytogether with keywater chemical parameters,water chemical parameters,decribesdecribes the Althe Al--activityactivity
4. SOM4. SOM--AlAlComplexationComplexation
AlAl complexedcomplexed to solidto solid Soil OrganicSoil Organic MatterMatter
{ }{ }
RAl H RH Al
RH
RAl
(3 ) 3
(3 )
− + + +
+
− + +
+ ⇔ +
=
aa
a
a a
a
KAl
HRAl
3
4. SOM4. SOM--AlAlContCont..
Rearranging the equationgives:
Approximation to identifyable parameters
gives:
{ } { }
{ }
Al RHRAl
K H
RHRAl
Al
pY pK
3(3 ) RAl
(3 )
3
RAl*
+
− +
+
− +
+
=
≈
=
= +
aa
a
aa
tot
org
tot
org
CAl
Y CAl
xpH
Amount of Carbon in soil
Al extracted with e.g. pyrophosphate
13
StrategyStrategy
ByBy analysing soilanalysing soil & soilwater& soilwater samplessamples from from differentdifferent environments we find empirical environments we find empirical relationships betweenrelationships between pAl, pH andpAl, pH and AlAlpyropyro/C/C
OtherOther relevant water parameters: SOrelevant water parameters: SO4422--, Ca, Ca2+2+, I, I
OtherOther relevantrelevant soilsoil parameters: Alparameters: AlCuClCuCl22,,AlAloxox
Field studiesField studiesPrecipitationPrecipitationThroughfallThroughfallSoilSoil waterwaterStreamStream waterwaterSoilsSoils
N
100 m
Liu Chong Guang siteSoil water samplers
Bottles for sample collection
Soil Soil
Throughfall sampler
IonsIons inin precipitationprecipitation µeq/L
HUMEXBirkenes Kosetice Czerniawka
Ratanica LCG TSP Guangzhou0
100
200
300
400
500
Locations
Ca2+Mg2+
Na+K+
NH4+
H+
NO3-
Cl-SO4²-
Norway CzechRepublic
Poland China
0.6 1.1
9.1
1.6
4.4
5.3
8-10
8-10
ExchangeableExchangeable cations incations in soilssoilsChinaChina PolandPoland/Norway/Norway
LeigongLeigong
ChonghuaGuiyang
NanshanTieshanPing
NanshanSiminanShan
LeigongDingHuShan
DingHuShanHeShan
DingHuShanBai Yun HUMEX
BrennaIngabekken
RatanicaJanow
BirkenesCzerniawka
Ciekon0
20
40
60
80
100
meq
/kg
BS HS AlS
13 11 11 83 34 31 44 53 47 26 37 39 34 22 7 58 30 28 16 43 26 74
IonsIons inin soilsoil waterwater
TieShanPingLiuChongGuang
RatanicaJanow
CzerniawkaBrenna
CiekonIngabekken
BirkenesHUMEX
0
200
400
600
800
1000
1200
1400
1600µe
q/L
H+ Ali NH4+ Na+K Ca+Mg SO4 NO3 F- Cl-
ChinaChina PolandPoland NorwayNorway
""Critical loadCritical load ratio"ratio"Al/(Ca+Mg)Al/(Ca+Mg)
““TheThe deposition below which significant harmful effectsdeposition below which significant harmful effectsdo notdo not occur accordingoccur according to presentto present knowledgeknowledge””
How doesHow does real soilwater datareal soilwater data fitfit the the GibbsiteGibbsite modelmodel??
3 4 5 6 7 82
4
6
8
10
12
pH
pAl
pK=-8.11
pK=-10.8
O
H
A
B
C
InIn manymany (most)(most) casescases the gibbsitethe gibbsite model model doesdoes notnot describedescribe the data at pH < 4.5the data at pH < 4.5
What doesWhat does the data tell us ?the data tell us ?
Gibbsite:Gibbsite:pAl =pAl = pKpKspsp + 3pH+ 3pH
Empirical fittingEmpirical fitting::pAl = pKpAl = pK00 ++ apHapH
ReussReuss et al., 1990: ret al., 1990: r22=0.75=0.75pAl = pAl = --2.29 + 1.65pH2.29 + 1.65pH
pKpKspsp::--8.118.11((synteticsyntetic))--10.8 10.8 ((amorphamorph))
Locality Hor. N r2 a pKAll All 797 0.58 1.6 -2.6
Birkenes H 85 0.93 1.7 -2.4Tieshanping A 44 0.84 1.7 -2.8Czerniawka A 15 0.94 2.6 -7.2Guiyang B 53 0.76 1.8 -4.0Tieshanping B 43 0.82 1.6 -2.7Guiyang C 84 0.80 1.7 -3.1Czerniawka C 70 0.87 2.2 -5.7Birkenes C 46 0.92 2.0 -4.3
DoesDoes thethe Jurbanite model describeJurbanite model describe thethefieldfield datadata better thanbetter than the Gibbsitethe Gibbsite modelmodel ? ?
0 2 4 6 8 10-14
-12
-10
-8
-6
-4
pK = pAl + pSO4 - pH (Jurbanite)
pK =
pA
l - 3
pH (G
ibbs
ite)
O
H
A
B
C
What doesWhat does the data tell us ?the data tell us ?pKsppKsp: 3.8: 3.8
((NordstomNordstom, 1982), 1982)JurbaniteJurbanite::pAl = pH - pSO4 + pKsp
EmpiricalEmpirical::pAl = apH + bpSO4 + pK
Locality Hor. N r2 a b pKAll All 796 0.63 1.6 0.7 -4.8Tieshanping All 86 0.83 1.5 0.5 -3.8Guiyang All 213 0.70 1.5 0.1 -2.8Czerniawka All 174 0.78 1.7 2.6 -12.5Birkenes All 214 0.57 1.3 0.4 -2.4
Birkenes H 84 0.93 1.6 0.3 -3.3Tieshanping A 43 0.84 1.6 0.3 -3.3Czerniawka A 14 0.95 2.7 -1.3 -2.7Tieshanping B 43 0.86 1.4 1.2 -5.6Guiyang C 83 0.80 1.7 0.1 -3.6Czerniawka C 69 0.87 2.2 0.4 -7.0Birkenes C 45 0.92 1.9 -0.3 -2.9
How doesHow does real datareal data fitfit the the SOMSOM--AlAl modelmodel ??
3 4 5 6 70
2
4
6
8
pH
pY
H
O
A
B
C
SOMSOM--AlAl modelmodelWesselinkWesselink et al., 1995: ret al., 1995: r22=0.82=0.82
pYpY = = --1.84 + 1.14pH1.84 + 1.14pH
Locality Hor. N r2 a pKAll All 295 0.67 1.6 -3.7Guiyang All 119 0.60 1.4 -2.9Czerniawka All 136 0.77 1.8 -4.6
Guiyang A 35 0.42 1.1 -1.9Czerniawka A 11 0.37 1.6 -3.1Guiyang B 35 0.62 1.3 -2.2Ratanica B 9 0.44 1.7 -4.0Guiyang C 42 0.65 1.2 -1.7Czerniawka C 45 0.82 3.0 -10.1
{ }pY p pK apH*RAl=
= ++Al3 C
Altot
org
What doesWhat does the data tell us ?the data tell us ?
ModelModel developmentdevelopment
pAl ispAl is empirically correlatedempirically correlated to:to:pH, pSOpH, pSO4 4 && p(p(AlAlorgorg//CCtottot))
We hypothesise that Al-mobilisation is controlledby a combined SOM-Al mechanismand sulfate desorption
RAlRAlnn++((nn½SO½SO4422--)+(3)+(3--nn)H)H++=RH =RH 33--nn+Al+Al3+3++(n½)SO+(n½)SO44
22--
pAl =pAl = pKpKSOMSOM--AlAl+ (3+ (3--n)pH n)pH -- (n½)pSO(n½)pSO4 4 + p(+ p(AlAlorgorg //CCTotTot))
Fitted empiricalFitted empirical to all data:to all data:pAl = pAl = -- 3.52 + 1.6 pH 3.52 + 1.6 pH -- 0.03 pSO4 + 0.8p(0.03 pSO4 + 0.8p(CCTotTot//AlAlpyropyro))
ModelModel testingtesting
pp∆∆ = = --loglog[(Σ[(Σ(10(10--pAlpAlmeasuredmeasured -- 1010--pAlpAlmodelledmodelled))22)/N])/N]1/21/2
GibbsiteGibbsite pAl = pAl = --2.6 + 1.6pH2.6 + 1.6pHJurbaniteJurbanite pAl = pAl = --4.8 + 1.6pH + 0.7pSO4.8 + 1.6pH + 0.7pSO44
SOMSOM--AlAl modelmodel pAl = pAl = --3.7 + 1.6pH + p(3.7 + 1.6pH + p(CCTotTot//AlAlorgorg))New combinedNew combined modelmodel pAl = pAl = --3.5 + 1.6pH 3.5 + 1.6pH -- 0.03pSO0.03pSO44 + 0.8p(+ 0.8p(CCTotTot//AlAlorgorg))
GibbsiteGibbsite JurbaniteJurbanite SOMSOM--AlAl NewNew
pp∆∆Alle 3.65 3.62 3.62 3.74Ciekonek 3.72 3.71 3.76 3.79Ratanika 4.21 4.42 4.19 4.51Guiyang 3.51 3.41 3.97 3.91Janow 4.07 4.10 3.47 3.71Czerniawka 3.53 3.73 3.66 3.69Tieshanping 3.92 3.57Birkeland 3.89 4.14
ConclusionsConclusions from from AlAl--mobilisation studiesmobilisation studies
DifferentDifferent mechanisms controlmechanisms control the Althe Al--mobilisation mobilisation dependingdepending on e.g. pH range and sulfateon e.g. pH range and sulfate concentrationsconcentrations
ComplexationComplexation of Al toof Al to soil organicsoil organic matter (SOMmatter (SOM--Al)Al) maymaydescribedescribe AlAl--activityactivity in mostin most Chinese soil watersChinese soil waters
In regions of high S-deposition Al mobilisationis best described by an combined pH dependent Al dissolution and sulfate desorption (“Jurbanite model”)
A combination of SOMA combination of SOM--AlAl dissolutiondissolution and and mobile anionmobile anion mobilisation appears promisingmobilisation appears promising
ConclusionsConclusions fromfrom field studiesfield studies
Very highVery high depositiondeposition ofof sulfursulfur atat some sitessome sitesWaterWater acidification onlyacidification only in small 1. orderin small 1. order streamsstreamsSoilSoil & soilwater& soilwater acidificationacidification isis likelylikely in largein large areasareas
LargeLarge spatial variationspatial variation inin soil chemistrysoil chemistryHighHigh concconc. of Al in. of Al in soilsoil water,water, but alsobut also high Cahigh Ca2+2+-- concconc..
Development in Development in S and CaS and Ca2+2+ deposition criticaldeposition critical
Laboratory experimentsLaboratory experimentsSoil columnsSoil columns:: Batch experimentBatch experiment::
1
1
2
Soil A Soil B
ConclusionsConclusions fromfromlaboratory experimentslaboratory experiments
SimpleSimple batch experiments yieldbatch experiments yield samesame resultsresults as moreas morecomprehensive soil column leaching experimentscomprehensive soil column leaching experimentsSulfateSulfate adsorptionadsorption onon YellowYellow-- and Redand Red soilsoil isis lowlowAlAl mobilisation correlatesmobilisation correlates best tobest to soilsoil pH andpH and AlAlorgorg
The base cationThe base cation weatheringweathering isis lowlow
Future soilFuture soil waterwater acidification depends acidification depends stronglystrongly onon changeschanges in base cationin base cationdepositiondeposition inin additionaddition to Sto S--depositiondeposition
Model workModel work
SimpleSimple equationsequations for:for:CationCation exchangeexchangeGibbsiteGibbsite solubilitysolubilitySulfateSulfate adsorptionadsorptionWeatheringWeatheringChargeCharge balancebalance
Model calibrationModel calibrationHindcastHindcast
ModelModel runningrunningSimulationSimulation && ForcastForcast
Magic simulationsMagic simulations
1970 1980 1990 2000 2010 2020 2030 2040 20500
0.2
0.4
0.6
0.8
Year
RC
L
No change +30%: Ca,Mg,SO4 - 80%: Ca,Mg,SO4
-30%: Ca,Mg -30%: SO4 +30%: SO4
1970 1980 1990 2000 2010 2020 2030 2040 20505
10
15
20
25
30
Year
BS
%
ConclusionsConclusions fromfrommodel studiesmodel studies
SoilSoil & soilwater& soilwater acidification may occuracidification may occur inin SouthernSouthern China China underunder longlong termterm acid depositionacid depositionPresentPresent deposition loadingdeposition loading givesgives minor changesminor changes
AnAn increaseincrease in sulfatein sulfate depositiondeposition or or aa decreasedecrease in base cationin base cation deposition deposition givegive rise torise to accelerated accelerated soilsoil and soilwaterand soilwater acidificationacidification
ConclusionsConclusions from PIACfrom PIACPrecursors for the formation of O3 and other photooxidants occur at high levels
Increased emissionsIncreased emissions of NOof NOxx may leadmay lead totoseriously increasedseriously increased OO33--concentrationsconcentrations
Damage to vegetation may be attributable to high levels of SO2, O3, lack of P or high Al content in soil water.Ecological effects of acidificationhave been observed on surface water organismsWaters low in dissolved saltsare found in rural areas with low acid loading at present
These watersThese waters areare poorly bufferedpoorly bufferedandand thereforetherefore very vulnerable tovery vulnerable to acidificationacidification