an investigation of the chemical composition of ... papers/pert vol. 7 (2) aug. 1984/08 pertanika...

9
Pertanika 7(2), 43-51 (1984) An Investigation of the Chemical Composition of Precipitation in and around Kuala Lumpur C. K. LEE andK. S. LOW Chemistry Department Faculty of Science and Environmental Studies Universiti Pertanian Malaysia, Serdang, Selangor. Malaysia, RINGKASAN Sampel hujan dikumpulkan pada tiga tempat di dalam dan di sekitar Kuala Lumpur dart Mei t 1982 ke Mei, 1983. Sampel-sampel dianalisiskan untuk pH t anion (sulfat, nitrat, klorida dan fluorida) dan kation (kalsium, magnesium, natrium dan kalium). Analisis korelasi dan regresi menunjukkan anion- anion utama kelihatan lebih berkaitan dengan kation-kation daripada ion hidrogen. Pencemar daripada kedua-dua sumber iaitu semulajadi dan oleh manusia nampaknya seolah-olah menentukan komposisi kimia bagi hujan. SUMMARY Individual rain event samples were collected at three sites in and around Kuala Lumpur from May, 1982 to May 1983. The samples were analysed for pH, anions (sulphate, nitrate, chloride and fluoride) and cations (calcium, magnesium, sodium and potassium). Correlation and regression analyses indicated that the major anions appeared to be more closely associated with the cations than the hydrogen ion. Pollutants from both natural and anthropogenic sources appeared to have contributed to the chemical composition of precipitation. INTRODUCTION The occurrence of acid precipitation has been well documented in the United States, Canada and Europe for more than a decade (Wisnienski and Keitz, 1983; Likens and Butler, 1981; Summers and Whelpdale, 1976; Martin and Barber, 1978, Ruppert, 1975). Source contributions to acid precipitation and the characterization of its chemical nature have also been investigated (Pratt*t al, 1983; Freely and Liljestrand, 1983; Me Naughton, 1981; Richardson and Merva, 1976). It was generally accepted that oxides of sulphur and nitrogen contributed to the acidity of the rain water. Previous work also suggested that acidity and concentrations of ionic components of precipitation have been increasing in certain geographic locations as a result of man's activities. Interest in precipitation chemistry in Malaysia was initiated by reports on the menace of acid rain and the knowledge that there has been increasing emission of pollu- tants to the atmosphere. The Malaysian Meteorological Service has been monitoring the pH of rainwater in the Klang Valley since 1976. Rainwater samples were collected monthly. The overall pH of rainwater samples in Petaling Jaya and Cameron Highlands were 4.5 and 5.4 respectively(New Straits Times, 13th June, 1983). There is, however, no data on the chemical com- position of rainwater. The present work was undertaken to investigate the acidity and chemical composition of rain in and around Kuala Lumpur. MATERIALS AND METHODS Individual rain event samples were collected from May, 1982 to May, 1983 at three sites: Kuala Lumpur city centre, Petaling Jaya resi- dential area and Serdang University Complex. The three sites are within 30 km of each other, with Petaling Jaya on the West and Serdang on the south of Kuala Lumpur. Kuala Lumpur has the highest traffic density. There *is no industrial polluting source in the immediate neighbourhood of the sampling sites, though there are some industrial activities in Kuala Lumpur and Petaling Jaya. Sequential static untis were used for col lection of rainfall samples through funnels into 250—cm 3 acid-washed polyethylene bottles (Copper et al, 1976). Only wet precipitation was collected. Following collection, the rainfall samples were taken to the laboratory and pH was measured within 24 hours of the event. 43

Upload: others

Post on 10-Mar-2020

9 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

Pertanika 7(2), 43-51 (1984)

An Investigation of the Chemical Composition ofPrecipitation in and around Kuala Lumpur

C. K. LEE andK. S. LOWChemistry Department

Faculty of Science and Environmental StudiesUniversiti Pertanian Malaysia,Serdang, Selangor. Malaysia,

RINGKASANSampel hujan dikumpulkan pada tiga tempat di dalam dan di sekitar Kuala Lumpur dart Meit

1982 ke Mei, 1983. Sampel-sampel dianalisiskan untuk pHt anion (sulfat, nitrat, klorida dan fluorida)dan kation (kalsium, magnesium, natrium dan kalium). Analisis korelasi dan regresi menunjukkan anion-anion utama kelihatan lebih berkaitan dengan kation-kation daripada ion hidrogen. Pencemar daripadakedua-dua sumber iaitu semulajadi dan oleh manusia nampaknya seolah-olah menentukan komposisikimia bagi hujan.

SUMMARY

Individual rain event samples were collected at three sites in and around Kuala Lumpur fromMay, 1982 to May 1983. The samples were analysed for pH, anions (sulphate, nitrate, chloride andfluoride) and cations (calcium, magnesium, sodium and potassium). Correlation and regression analysesindicated that the major anions appeared to be more closely associated with the cations than the hydrogenion. Pollutants from both natural and anthropogenic sources appeared to have contributed to the chemicalcomposition of precipitation.

INTRODUCTION

The occurrence of acid precipitation has beenwell documented in the United States, Canadaand Europe for more than a decade (Wisnienskiand Keitz, 1983; Likens and Butler, 1981; Summersand Whelpdale, 1976; Martin and Barber, 1978,Ruppert, 1975). Source contributions to acidprecipitation and the characterization of itschemical nature have also been investigated(Pratt*t al, 1983; Freely and Liljestrand, 1983;Me Naughton, 1981; Richardson and Merva,1976). It was generally accepted that oxidesof sulphur and nitrogen contributed to theacidity of the rain water. Previous work alsosuggested that acidity and concentrations ofionic components of precipitation have beenincreasing in certain geographic locations as aresult of man's activities. Interest in precipitationchemistry in Malaysia was initiated by reportson the menace of acid rain and the knowledgethat there has been increasing emission of pollu-tants to the atmosphere. The MalaysianMeteorological Service has been monitoring thepH of rainwater in the Klang Valley since 1976.Rainwater samples were collected monthly. Theoverall pH of rainwater samples in Petaling Jayaand Cameron Highlands were 4.5 and 5.4

respectively(New Straits Times, 13th June, 1983).There is, however, no data on the chemical com-position of rainwater. The present work wasundertaken to investigate the acidity and chemicalcomposition of rain in and around Kuala Lumpur.

MATERIALS AND METHODS

Individual rain event samples were collectedfrom May, 1982 to May, 1983 at three sites:Kuala Lumpur city centre, Petaling Jaya resi-dential area and Serdang University Complex.The three sites are within 30 km of each other,with Petaling Jaya on the West and Serdang onthe south of Kuala Lumpur. Kuala Lumpur hasthe highest traffic density. There *is no industrialpolluting source in the immediate neighbourhoodof the sampling sites, though there are someindustrial activities in Kuala Lumpur and PetalingJaya.

Sequential static untis were used for collection of rainfall samples through funnels into250—cm3 acid-washed polyethylene bottles(Copper et al, 1976). Only wet precipitationwas collected. Following collection, the rainfallsamples were taken to the laboratory and pHwas measured within 24 hours of the event.

43

Page 2: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

CK. LEE AND K. S. LOW

The sample bottles were then sealed and storedin a freezer until subsequent chemical analysis.

The pH measurements were made with astandard pH meter after calibrating at pH4.00 and 7.00. Chloride and fluoride concen-trations were determined using Orion ion-selective electrodes and the digital Orion ion-analyser 901. Nitrate concentrations were deter-mined using the brucine method (Jenkinsand Medsker, 1964). Sulphate concentrationswere quantified by inductively coupled emis-sion spectrometry (Miles and Cook, 1982), sowere the concentrations of calcium, magnesium,sodium and potassium. A labtest Plasmascan 710was used.

The data were converted to fjieq dm forstatistical analysis. Values below the detectionlimit for a given constituent were arbitrarilyassigned a value of one-half of the detection limitfor that component (Pratt et al.t 1983). Fluorideand potassium concentrations were not includedfor statistical analyses as their mean concen-trations were not significantly different from theirlimits of detection.

RESULTS AND DISCUSSION

The means, standard errors and ranges of themajor components for precipitation collectedfrom May, 1982 to May, 1983 are given in Table1. The monthly ranges of these major componentsare listed in Table 2. Partial data were obtainedfor nitrate and chloride concentrations as thevolume of these liquids was insufficient forall analyses.

The acidity of rain water collected at thethree sites are in the order of Petaling Jaya >Serdang > Kuala Lumpur. The relative acidityor alkalinity of rainfall is affected by thepresence of both acid-producing and alkali-producing constituents in the rainfall. Theseconstituents may be present in either easeousor particulate form and may be derived fromeither natural or anthropogenic sources. In theabsence of major pollutants, raindrops fallingthrough the atmosphere will reach anequilibrium with carbon dioxide which dissolvesin water to produce an equilibrium pH of 5.7(Gorham, 1976). The average pH of the rain waterare 4.10, 4.30 and 4.80 at Petaling Jaya,Serdang and Kuala Lumpur respectively. Thesevalues are below that of 'neutral* rainfall. There is,however, ^reat variation in the pH between events.In Kuala Lumpur, for example, it ranged from3.1 to 7.3.

In general, the concentrations of the majorcomponents are higher in Kuala Lumpur than inPetaling Jaya and Serdang. There is, however,wide variations in the ionic concentrationsbetween events. It has been observed that concen-trations of ions may vary within a rain event,between events and between locations (Liljestrand,1979; Hales, 1981, c.f. Pratt et at., 1983). Thisis due to differences in the origins of thematerials present in the precipitating air massand differences in the meteorology andatmospheric chemistry within events, betweenevents and between locations.

Concentrations of fluoride in all the eventsare below O.lmg dm"3. This is as expected asthere are no specific fluoride-emitting indus-tries in the vicinity of the sampling sites.

Sea spray has been cited as one of themajor natural sources of sulphate, nitrate, alkaliand alkaline earth elements in precipitation(Gorham, 1976; Martin and Barber, 1978). The

ratios of SO4 /Na, Cl/Na and Mg/Na in seaspray were ^quoted as 0.25, 1.8 and 0.12 respec-tively (Sverdrup et aL, c.f. Martin and Barber,1978). The ratios of SO4/Na are 3.69, 4.22and 3.23 in Kuala Lumpur, Petaling Jaya andSerdang respectively. This indicates that a veryhigh percentage of sulphate in rainwater is notof maritime origin. One of the likely sources isthe combustion of petroleum fuels and auto-mobile gasoline (Ruppert, 1979). On the otherhand, the ratios of Cl/Na are 1.4, 1.5 and 1.3,and the ratios of Mg/Na are 0.18, 0.12 and 0.09for Kuala Lumpur, Petaling Jaya and Serdangrespectively. It thus appears that sea spray isthe main source for chloride, magnesium andsodium in the rain water. These elements arestrongly correlated with one another (Tables3 and 4). Strong correlation between these ionicconcentrations is probably the result of commonresources, though it may also be the result ofcommon scavenging mechanisms or chemicalreaction mechanisms.

The ratio of Mg/Ca in sea spray is 3.16(Eriksson, 1952). The ratios calculated for rain-water samples at Kuala Lumpur, Petaling Jayaand Serdang are around 0.07. This clearlyindicates that like sulphate, a high percentageof calcium in rain water does not originate fromsea spray. Limestone and cement dust contributesa high percentage of calcium (Gorham, 1976).Combustion of refuse, both domestic andindustrial, supplied alkali and alkaline earthmetals to the fly dust (Ruppert, 1979). Themajor source of calcium in precipitation thusappears to be from man made activities.

44

Page 3: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

TABLE 1Rainfall (mm), pH, H (/ieg dm^3) and mean concentrations

(mg dm~3) of th e m a j o r components in precipitation

Site

Kuala Lumpur

Pctalingjaya

Serdang

MeanS.E:MinimumMaximumNo. of events/analysis

MeanS.E.MinimumMaximumNo. of events/analysis

MeanS.E.MinimumMaximumNo. of events/analysis

Rainfall

33.343.55

1.14166.40

120

27.542.24

.0896.62

99

34.183.072.44

117.73

80

pH

4.82.07

3.107.30

120

4.12.07

3.10

6.50

99

4.38.07

3.506.10

80

15.376.78.05

294.33

120

76.8911.17

.32794.33

99

42.356.26

.79316.23

80

Ca2 +

2.75

.20.19

12.23

112

.95

.08.11

4.44

98

1.25.12.14

5.94

80

Na+

1.07.11.05

4.11

119

.68

.09<D.L.

4.45

98

.96

.11<D.L.

5.54

80

Mg2 +

.20

.02<D.L.

1.30

117

.08

.007<D.L.

.38

97

.09

.008<D.L.

.40

80

<

1 V• M

niJ

* t^y%iii±f*.U

nFd

9

3.95.22.28

18.39

114

2.87.18.14

7.47

96

3.10.17.46

6.84

75

NO3

2.21.17

<D.L.9.66

63

1.36.11

D.L.3.77

62

1.08.20

<D.L.9.35

51

C l ~

1.54.44.61

5.63

49

1.05.09

.36 ;4.95

52

1.22.10.52

4.20

46

H

concentrations were < 0.1 mg dm 3 ;Q

[ueq dm~ / was calculated from pH values. - 3D.L. for Na+ , Mg2+ and NO^ are 0.002, 0.00004 and 0.04 mg dm D respectively.For concentrations below D.L., an arbitrary value of V2 D.L. was used in the computation of the mean and S.E.

<

O

ooH

tn

gIOrno

IH

5

3

mQ

o

>

o

arr

Page 4: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

TABLE 2 _i, Q

Monthly range of rainfall (mm), H £|Uegdm ) and major chemical components(mg dm~ ) in precipitation.

KualaLumpur

PetalingJaya

Serdang

Year

1982

1983

1982

1983

1982

1983

Month

MayJuneJulyAug.Sept.Oct.Nov.Dec.Jan.Feb.Mar.AprilMay

MayJuneJulyAug.Sapt.Oct.Nov.Dec.Jan.Feb.Mar.April.May

MayJuneJulyAug.Sept.Oct.Nov.Dec.Jan.Feb.Mar.AprilMay

* ^ _

Rainfall

L14-119.803.09-153.46

14.13-166.404.87-134.78L95-137.204.22- 94.026.98-113,355.20- 14.132-92- 60.081.95- 47.093.73- 56.845.68-106.044.22- 71.78

1.14-69.340.08-69.83

17.86-64.142.60-73.080.57-96.623.17-70.942.96-85.25

30.04-64.967.47-29.48

12,34-56.848.77-32.487.31-81.20

34.75-44.66

2.66-44.222.44-71.454.89-65,774.87-53.59

12.84-47.913.90-25.414.87-87.09

20.30-51.9610.26-66.264.96-26.28

10.23-89.3145-79-117.7310.23-108.30

H+

0.14-1.990.05-3.980.13-25.120.13-10.000.50-22.390.06-39.810.20-794.330.44-4.270.12-79.430.63-39.810.25-35.480.25-125.900.40-22.39

0.40-39.817.94-63.10

17.78-70.793-16-112.206.31-79.430.13-199.537.94-398.11

14.13-794.330.32-44.673.16-141.25

12.59-199.5335.48-398.1131.62-100,00

12.59-39.810.40-22.393.16-25.120.79-125.895.01-100.000.79-70.79

15.84-316.231.00-50.127.94-112.201.78-223.870.40-31.62

22.39-50.1215.84-125.89

uar ,,f events does not

Ca2+

2.46-10.492.26-12.233.48-5.332.78-6.110.36-2.150.69-8.100.55-2.951.71-2.700.19-1.700.62-2.610.71-4.300.75-4.300.69-2.64

0.30-1.380.12-2.120.18-0.880.29-1.770.30-0.880.16-1.080.11-1.170,28-1.760.19-4.440.96-3,001.36-2.550.81-3.510.20-1.54

0.32-1.700.20-4.100.35-4.510.68-3.130.43-3.850.16-5.940.14-1.630.40-0.920.73-3.120.50-0.841.91-3.150.90-1.950.48-1.98

Na+

0,59-2.210,90-8.100.98-2.780.83-2.940.36-2.150.41-4.110.09-2.900.20-0.790.05-1.650.10-1.310.10-3.010.15-0.950.07-2.22

0.07-0.710.08-1.810.53-0.900.13-2.60

<D.L.-0.5 3< D.L.-1.88< D.L.-0.47

0.08-0.690.01-4,450.29-1.321.11-2.370.96-2.74

< D.L.-0.70

0.28-1.510.22-2.090.28-1.580.29-3.340.17-1.630.20-2.75

< D.L.-0.930.14-1.741.71-5.340.84-1.471.14-5.540,18-1.540.02-3.29

Mg2+

0.12-0.990.16-1.300.16-0.350.13-0.390.08-0.680.04-0.520.03-0.220.19-0.230.02-0.270.06-0.260.06-0.46

<D.L.-0.340.04-0.15

0.02-0.060.01-0.070.03-0.160.03-0.380.02-0.100.01-0.080.08-0.130.03-0.110.02-0.230.08-0.28

mn 12-0.23<D.L.-0.19

0.02-0.07

<D.L.-0.120.02-0.290,05-0.400.06-0.300.07-0.210.02-0.260.01-0.120.03-0.150.04-0.230.05-0.100.10-0.150.04-0.110.02-0.10

3.82-7.562.71-18.394.28-7.973.10-9-391.17-7.851.24-9.351.01-2.932.82-3.870.28-4.941.34-5.171.44-6.402.21-6.720.82-3.87

1.80-4.320.21-4.370.79-5.062.02-6.192.074.850.84-5.321.04-2.810.36-1.160.14-7.471.38-7.473.60-5.151.91-6.210.534.55

2.23-5.071.27-5.073.51-4.752.71-5.622.684.652.05-6.8404*4.50

11.9.3.05-*./.2.824.421.234.39

necessarily equal to the number of analysis.

NOJ

5.23-8.335.09-9.664.65-7.532.30-5.322.48-4.611.95-4.74

< D.L.-2.610.27-2.57

< D.L-2.26< D.L.-2.04

0.22-1.550.35-2.300.02-1,73

0.66-0.950.22-1.020.31-1.281.28-3.280.71-1.150.75-2.04

<D.L.-2.300.53-0.660.84-3.771.86-3.061.86-2.440.31-3.26

<D.L.-1.37

0.09-0.440.660.44-1.731.11-1.331.02-2.530.27-1.200.27-2.44

< D.L.-0.841.334.390.58-3.010.58-1.990.09-9.35

< D.L.-3.29

C l ~

1.94-5.631.80-2.540.89-1.181.51-2.931.34-3.041.33-2.010,65-3.16N.D.0.70-1.431.660.64-1.180.730.61-1.16

0.96-1.330.71-1.751.094.951.40-2.420.85-1.740.78-1.370.36-1.370.73-1.370.66-1.220.71-0.941.11-1.210.89-1.200.55-0.82

0.67-1.530.59-0.781.00-2.701.69-1.771.18-2.340.63-2.180.63-1.380.60-0.961.39-1.651.08-1.111.304.200.72-1.330.52-1.27

•Numberof

events

696

107

1013577

121018

565

107

1517

675574

46466

1117

534347

nP

i>9c«

Q

Page 5: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

AN INVESTIGATION OF THE CHEMICAL COMPOSITION OF PRECIPITATION IN AND AROUND KUALA LUMPUR

TABLE 3Matrix of correlation coefficients for the major components

Q

(/Lteg dm ) and rainfall (mm) for all the samples.

H+

Ca2 +

Na+

Mg2 +

so^-NO3

cr

Ca2 +

-0.172**(290)

Na+

-0.096(294)

0.520***(290)

Mg2+

-0.164**(294)

0.888***(287)

0.454***(293)

SO^f

-0.056(285)

0.717***(278)

0,545***(285)

0.776***(283)

NOJ

-0.087(177)

0.669***(175)

0.402***(177)

0.592***(175)

0.608***(170)

C l "

-0.172*(H5)

0.529***(144)

0.550***(145)

0.673***(144)

0.603***(138)

0.458***(121)

Rainfall

-0.001(299)

-0.005(290)

-0.122(297)

-0.135(294)

-0.061(285)

0.238**•(177)0.027(145)

Level of significance : * p( ) • number of samples. •* p

*** c

<. 0.050.0050.0005

TABLE 4Correlation Coeff cients for the Major Components, (/ieg~ ) at

Kuala Lumpur, Petaling Jaya and Serdang separately.

H +

H +

H +

H +

H +

H +

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Na+

Na+

Na+

Na+

M g 2 lMg2/SO"1"

NOT

Relationship

vsvsvsvsvsvsvsvsvsvsvsvsvsvsvsvsvsvsvsvsvs

Ca*+

Na+

Mg2 +

SO4-NO 3

C l "Na+

Mg2+

S O | "NO 3

C l "Mg2+

SO 4 2-NO3

ca ;so4

2~NO3

ciiNO~C l "C l ~

Kuala Lumpur (n)

-0.127 (112)-0.112 (119)-0.095 (117)-0.082 (114)-0.224 (64)-0.284* (47)

0.489*** (112)0.874*** (111)0.765*** (107)0.807*** (62)0.633*** (46)0.394*** (117)0.509*** (114)0.723*** (64)0.693*** (47)0.799*** (113)0.656*** (63)0.766*** (47)0.775*** (62)0.593*** (44)0.685*** (41)

Petaling Jaya (n)

0.144 (98)0.033 (98)0.021 (97)0.116 (96)0.013 (62)0.031 (52)0.806*** (98)0.826*** (96)0.713*** (96)0.459*** (62)0.072 (52)0.730*** (96)0.610*** (96)0.375** (62)0.289* (52)0.774*** (95)0.451*** (61)0.424** (51)0.449*** (61)0.538*** (51)

-0.033 (42)

Serdang (n)

-0.187 (80)-0.106 (80)-0.189 (80)

0.013 (75)0.130 (51)

-0.128 (46)0.548*** (80)0.857*** (80)0.714*** (75)0.194 (51)0.660*** (46)0.536*** (80)0.567*** (75)0.314* (51)0.373* (46)0.744*** (75)0.198 (51)0.694*** (46)0.288* (47)0.538*** (43)0.116 (38)

Level of significance: * P < 0.05** P < 0.005

*** P ^ 0.0005

47

Page 6: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

CK. LEE AND K. S. LOW

Fig 1 shows the mean concentrations ofseveral ionic components as a function of pH.The mean concentrations of these ionic com-ponents generally increase with increasing pH.The increase is especially notable for calcium.This trend is expected for the cations but notfor the anions. Based on the assumption thatthe acidity of precipitation arises from thepresence of H2SO4 and HNO3, one would expectthe concentrations of sulphate and nitrate icnsto be highest at the lowest pH. However, this

is not observed in the present study. Thiscould partially be explained by the extremelyhigh concentrations of calcium which appearto have a buffering effect on acidity. Thisbuffering effect had also been observed earlier(Cooper et alM 1976; Gorham, 1976). Correla-tions between hydrogen ion and either sulphateor nitrate were low at all pH ranges (Table5). On the other hand, calcium, magnesium andsodium were highly correlated with sulphateand nitrate.

180

160 "

140 -

4 120

I2 100 -

8 80

8c

S 60

40 -

20 ~

qusA

* © 3

Ca 2 +

Fig. 1. Mean concentrations of chemical components (ixeq dm3) as a function ofpH.

48

Page 7: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

H +

H+-

H+

H+

H+

H+

C a 2 +

C a 2 +

C a 2 +

C a 2 +

C a 2 +

Na+

Na+

Na+

Na+

N g 2 +

M g 2 +

N g 2 +

so 2 -so2~NO~

Level

Relationship

vs

vs

vs

vs

vs

vs

vs

vs

vs

vs

VS

vs

vs

vs

vs

vs

vs

vs

vs

vs

vs

Ca2 +

Na+

Mg2 +

s o 2 -

Na+

Mg2 +

SO2""

N O "

Mg2 +

s o 2 -NO4-

o

C l "so 2 -NO~

C l ~

N O -3

Cl~c i -

of significance ~ *P

**p***p

< 4.0(n)

0.462*(30)0.098(30)0.307(29)0.098(30)0.167(15)0.119(17)0.793***(30)O.77O***(29)O.543**(3O)0.561*(15)0.550* (17)0.678***(29)

0.382*(30)O.7O7**(15)0.549*(17)0.702***(29)O.556*(14)0.731**(16)0.716**(15)0.383(17)0.257(13)

< 0.05< 0.005< 0.0005

TABLE 5Correlation coefficients by pH range

4.0-4.5(n)

-0.287*(71)-0.218(71)-0.211(70)-0.130(66)

0.037(50)-0.0.30(45)

0.442***(71)0.798***(70)0.678***(66)0.413**(50)0.201(46)0.380**(70)0.457***(66)0.203(50)0.281(46)0.807***(66)0.417**(50)0.375* (46)0.399**(47)0.523***(44)0.089(40)

> 4.5-5.0(n)

-0.166(67)0.006(67)

-0.164(68)-0.117(65)

0.038(44)0.024(41)0.570***(67)0.919***(67)0.838***(65)0.595***(44)0.670***(41)0.551***(67)0.602***(65)0.348*(44)0.637***(41)0.841***(65)0.574***(44)0.703***(41)0.673**(43)0.698***(39)0.582***(32)

>5.0-5.5(n)

-0.211(44)-0.108(45)-0.209(45)-0.205(44)

0.012(30)-0.381(16)

0.591***(44)0.901**(44)0.864***(43)0.520**(30)0.551*(16)0.502***(45)0.628***(44)0.673***(30)0.802***(16)0.917***(44)0.424*(30)0.558*(16)0.605**(29)0.751**(15)0.516*(15)

b .-

>5.5-6.0(n)

-0.208(34)-0.059(35)

-0.233(35)-0.161(33)-0.170(19)-0.015(10)

0.507**(34)0.880***(34)0.788***(32)0.789***(19)0.811**(10) i

0.496**(35)0.650***(33)0.380(19)0.634*(10)0.731***(33)0.580*(19)0.827**(10)0.660**(18)0.538(8)0.886**(9)

>6.0(n)

-0.083(44)^0.217(49)

0.021(47)0.140(47

-0.122(19)0.224(15)0.247(44)0.827***(43)0.715***(42)0.688**(17)

fc 0.152(14) ^0.152(47)0.380(47)0.088(19)0.356(15)0.632***(46)0.522*(18)0.644*(15)0.601*(18)0.334(15)0.166(12)

^ >

% ro :::j> **,i j „>

o *rO 5r

H ^X ...•-

cn ,

3 ::1 -O/—\

iO

H{**.\j

*Z

o

O

3z[—*>

1n)K

UA

L

a3P

Page 8: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

CK. LEE AND K. S. LOW

The variance in acidity in precipitationhas been attributed to sulphate ions alone(Me Naughton, 1981), nitrate ions alone (Lewisand Grant, 1980) and both the two anionstogether (Feeley and Liljestrand, 1983; Gallo-way and Likens, 1981; Richardson and Merva,1976). However, no significant correlationbetween hydrogen ions and either sulphate ornitrate ions is noted in the present study(Tables 3, 4 and 5). Kasina (1980) also foundno correlation between the increase in sulphateand the decrease in pH of precipitation.Acid components such as sulphate andnitrate ions can be neutralized partly by alkalinesubstances. Multiple regression analyses wereused to determine which cations may beassociated with the anions (Table 6). Forsulphate, magnesium was the best predictor inthe model while calcium was the bestpredictor for nitrate. This indicates that in themajority of rain events at our samplingsites, most of the sulphate and nitrate were notassociated with the hydrogen ion. Instead,they occurred as salts associated with other

cations [eg. MgSO4 and Ca(NO3)2]. Whilesome of the measured free hydrogen ionswere no doubt donated by strong acids ofsulphate and nitrate, weak and organicacid could have accounted for themajor portion. Similar observations weremade by Pratt et al. (1983). Possible explanationsare (i) the sampling sites may be recipients ofalkaline dust such as from limestone quarriesin the region and (ii) as the sampling sites are notin the vicinity of severe pollution sources, airmasses seem to have a long atmospheric residencetime in which to undergo chemical reactionsbefore deposition in a rain event.

Further work including analysis of dry pre-ciptation will have to be carried out to examinethe effect of dustfall on the chemical composi-tion of rain water. Data collected over severalyears are needed to arrive at meaningful eva-luations and correlations between differencesin composition with time and type ofmeteorological event.

TABLE 6Cationic predictors of sulphate and nitrate concentrations from

the stepwise multiple regression model.

Dependent variable All the three sites Individual sites

Kuala Lumpur Petaling Jaya Serdang

[so. Mg2+

Ca2+

R2 - ,61

Ca2+

2+Mg-

R2 • 47

Mg

Ca5

H +

2+Mg2+

Ca2+

R2 = .64

Ca 2 +

Na+

Mg2 +

RZ - .74

R2

2

= .62

Ca 2 +

= .22

.2+Mg

Na+

H+

R2 = .63

R2 = 10

The cations arc listed in order of importance.

50

Page 9: An Investigation of the Chemical Composition of ... PAPERS/PERT Vol. 7 (2) Aug. 1984/08 Pertanika Vol.07...An Investigation of the Chemical Composition of Precipitation in and around

AN INVESTIGATION OF THE CHEMICAL COMPOSITION OF PRECIPITATION IN AND AROUND KUALA LUMPUR

CONCLUSION

Precipitation was collected and analysedfor the period of May, 1982 to May, 1983 inand around Kuala Lumpur. Spatial and temporalvariations in the concentrations of chemicalcomponents in the rain water were observed.There appeared to be contributions ofboth natural and anthropogenic sources ofpollutants to the composition of precipitation.Sulphate and nitrate were the predominant,anions; they appeared to be associated morewith metallic cations than with hydrogenions.

ACKNOWLEDGEMENT

The authors wish to thank Mr. Loh ChoonFatt of Standards and Industrial ResearchInstitute, Malaysia, Ms Choo Chai Syam ancl Mr.Sri Jegan for assisting in the collection ofrainfall samples and measurement of pH.Thanks are also due to Mr. Tham Wing Soon forpartial analysis of fluoride and sulphate andMr. Siow Kiat Foo for assisting in statisticalanalyses.

REFERENCES

COGBILL, CV. (1976): The history and character ofacid precipitation in eastern north America. Water,Air and Soil Poll. 6 : 407^13.

COOPER, JR. H.B.H., LOPEZ, J.A. and DEMO, J.M.(1976): Chemical composition of acid precipitationin central Texas. Water, Air and Soil Poll. 6 : 351-359.

ERIKSSON. E. (1952) Composition of atmosphericprecipitation. I. Nitrogen compounds. Oikos :215-232.

FREELEY J.A. AND LILJESTRAND, H.M (1983):Source contributions to acid precipitation inTexas. Atm. Environ. 17 : 807-814.

GALLOWAY J.N. AND LIKENS. G.E. (1981): Acidprecipitation: the importance of nitric acid.Atm. Environ. 15 : 1081-1085.

GORHAM.E. (1976): Acid precipitation and its influenceupon aquatic ecosystem-an overview. Water, Airand Soil Poll 6 : 457-481.

HALES. J.M. (1981): Precipitation chemistry. Itsbehaviour and its calculation. In The InternationalConference on Air Pollutants and their Effectson the Terrestrial Ecosystem. John Wiley and Sons.

JACOBSON, J.S., HELLER, L.L and LEUKEN, P.V.(1976): Acid precipitation at a site within thenortheastern Conurbation. Water, Air and SoilPoll. 6 : 339-349.

JENKIS,D. and MEDSKER, L.L. (1964): Brucine methodfor determination of nitrate in ocean estuarineand fresh waters. Anal. Chem. 36 : 610-662.

KASINA, S. (1980): On precipitation acidity in south-eastern Poland. Atm. Environ. 14: 1217-1221.

LEWIS, W.M. Jr and GRANT M.C. (1980): Acid pre-cipitation in the Western United States. Science :207 : 176-177.

U K E N S G.E. and BUTTER, T.L. (1981): Recentacidification of precipitation in North America.Atm. Environ. 15 : 1103-1109.

LILJESTRAND, H.M. (1979): Atmospheric transportof acidity in Southern California by wet and drymechanisms. Ph.D. thesis, California Instituteof Technology, Pasadena, California.

MARTIN. A. and BARBER, F.R. (1978): Some obser-vations of acidity and sulphur in rainwater fromrural sites in central England and Wales. Atm.Environ. 12: 1481-1487.

MC NAUGHTQN. D.J. (1981): Relationships betweensulphate and nitrate ion concentrations, andrainfall pH for use in modelling applications. Atm.Environ. 15 : 1075-1079.

MILES, D.L. and COOK, J.M. (1982): The determinationof sulphate in natural waters by inductively-coupledplasma emission spectrometry. Anal. Chim. Acta,141 : 207-212.

New Straits Times, Malaysia, 13th June, 1983.

PRATT, G.C., Coscio, M.f GARDNER, D.W.,CHEVONE, B.L and KRUPA. S.V. (1983): Ananalysis of the chemical properties of rain in Minnes-ota, Atm. Environ. 17 : 347-355.

RICHARDSON, C.J. and MERVA. G.E. (1976): Thechemical composition of atmospheric precipitationfrom selected stations in Michigan. Water, Air andSoil Poll. 6 : 385-393.

RUPPERT, H. (1975): Geochemical investigations onatmospheric precipitation in a medium-sized city.Water, Air and Soil Poll 4 : 447^60.

SUMMERS, P.W. and WHELPDALE, D.M. (1976):Acid precipitation in Canada. Water, Air and SoilPoll 6 : 447-455.

SVERDRUP, H. U., JOHNSON. M.w. and FLEMING,R.H. (1949): The oceans, their physics, chemistry andgeneral biology. New Jersey Prentice-Hall, Engle-wood Cliffs.

WiSNIEWSKl, J. and KEITZ. E.L. (1983): Acid raindeposition patterns in the continental United States.Water, Air and Soil Poll. 19 : 327-339.

Received 7 January 1984.

51