Five-year monitoring study of chemical characteristics of Wetatmospheric precipitation in the southern region of Jordan

Omar Ali Al-Khashman & Aiman Qasem Jaradat &Elias Salameh

Received: 2 April 2012 /Accepted: 22 October 2012 /Published online: 10 November 2012# Springer Science+Business Media Dordrecht 2012

Abstract Wet atmospheric samples were collectedfrom different locations in the southern region ofJordan during a 5-year period (October 2006 toMay 2011). All samples were analyzed for pH,EC, major ions (Ca2+, Mg2+, Na+, K+, HCO3

−,Cl−, NO3

−, and SO42−), and trace metals (Fe2+,

Al3+,Cu2+, Pb2+, and Zn2+). The highest ion con-centrations were observed during the beginning ofthe rainfall events because large amounts of dustaccumulated in the atmosphere during dry periodsand were scavenged by rain. The rainwater in thestudy area is characterized by low salinity andneutral pH. The major ions found in rainwaterfollowed the order of HCO3>Cl

−>SO42− and

Ca2+>Na+ > Mg2+ > NH4+ > K+. Trace metals

were identified to be of anthropogenic originresulting from cement and phosphate mining activ-ities located within the investigated area and fromheating activities during the cold period of theyear (January to April). The wet precipitationchemistry was analyzed using factor component

analysis for possible sources of the measured spe-cies. Factor analysis (principal component analysis)was used to assess the relationships between theconcentrations of the studied ions and their sour-ces. Factor 1 represents the contribution of ionsfrom local anthropogenic activities, factor 2 repre-sents the contribution of ions from natural sources,and factor 3 suggests biomass burning and anthro-pogenic source. Overall, the results revealed thatrainwater chemistry is strongly influenced by localanthropogenic sources rather than natural and ma-rine sources, which is in a good agreement withthe results obtained by other studies conducted insimilar sites around the world.

Keywords Precipitation chemistry . Acidityneutralization .Major ions . Factor analysis . Jordan

Introduction

Wet precipitation is the most effective scavengingprocess for removing particulates and dissolved organ-ic gaseous pollutants from the atmosphere. The scav-enging of atmospheric pollutants affects the chemicalcomposition and the pH of wet precipitation (Al-Khashman 2005a). The chemical composition of wetprecipitation varied from site to site and from region toregion due to differences in the local sources, and it isstrongly affected by the chemical composition of theatmosphere (Cao et al. 2009). Atmospheric

Environ Monit Assess (2013) 185:5715–5727DOI 10.1007/s10661-012-2978-1

O. A. Al-Khashman (*) :A. Q. JaradatDepartment of Environmental Engineering, Faculty ofEngineering, Al-Hussein Bin Talal University,P.O. Box 20, Ma’an, Jordane-mail: omarkhashman@yahoo.com

E. SalamehDepartment of Applied Geological and EnvironmentalSciences, Faculty of Science, University of Jordan,Amman 11191, Jordan

precipitation contains substances of anthropogenic or-igin such as gases and particulates emitted from in-dustrial activities and of natural origin such as Mg2+,Ca2+, and HCO3

− originated from sea salt and soil dust(Budhavant et al. 2011).

The chemical composition of wet precipitationreflects all the local characteristics of air pollutants(Sakihama et al. 2008). Acidic precipitation is primar-ily related to the emissions of SO2 and NOx into theatmosphere since these gases are the precursors ofmajor acids H2SO4 and HNO3 (Anatolaki andTsitouridou 2009; Das et al. 2010; Migliavacca et al.2005). On the other hand, neutralization of acidity inrainwater can be either due to the presence of CaCO3

in airborne dust (Munger 1982; Salameh and Rimawi1988; Salameh et al. 1991) or due to ammonia releasefrom anthropogenic (industrial and agricultural) ornatural sources (Schuurkes et al. 1988).

The toxic metals, notably, Cu, Cr, Ni, and Pb,are present in the atmosphere as a result of theiremission from agricultural and industrial activities,particularly those that require high temperature inprocessing such as non-ferrous metal smelting andfossil fuel combustion. These metals can stay inthe atmosphere for a long time until they areremoved by a variety of cleaning processes suchas dry deposition, scavenging, and washout by rain(Bergametti et al. 1989).

Several studies addressing the rain water qualityin the Mediterranean region and the factors affect-ing its composition were conducted to date(Kubilay and Saydam 1995; Bergametti et al.1989; Gullu et al. 1998; Tuncer et al. 2001; Al-Khashman 2005a). They conclude that there aretwo main sources that strongly affect the compo-sition of atmospheric particles and precipitation inthe Mediterranean Basin, including the aeoliandust transported from North Africa and aerosolstransported from Europe. However, few attemptshave been made to investigate rain water qualityin Jordan (Salameh and Rimawi 1988; Al-Momaniet al. 2000; Al-Khashman 2005a; b). This paperrepresents a 5-year study (2006–2011) of wet pre-cipitation composition carried out on a daily basisin the Shoubak area located in the southern part ofJordan. The main objective of this study was toexamine the ionic composition of precipitation andto identify the sources of the various constituentsfound in the wet precipitation in this region.

Materials and methods

Sampling site

The study area is located in the southern part of Jordan(about 210 km south of Amman) and it is bounded bythe coordinates latitude 30°31′ N and longitude 35°32’E (Fig. 1). There is a great variation in the nature of thetopography in the area. The elevation varies from1,340 m above mean sea level in the western area toa maximum altitude of 1,734 m above sea level in thesouthern area. The study area in general is arid tosemiarid and is marked by sharp seasonal variationsin both temperature and precipitation. The mean an-nual rainfall amount measured during the last twodecades is around 285 mm (Department ofMeteorology 2010). Winter in Jordan (October untilthe end of April) is the principal season of rainfall. Theaverage temperature is 20.3 °C, with a minimum valueof −1.0 °C in January and a maximum of 33.5 °C inJuly (Department of Meteorology 2010; Shehdeh1991). The maximum sunshine duration occurs inJune with absolute values of 12.1 h/day, but in winter(December and January) the average minimum sun-shine is only about 4.3 h/day. The average relativehumidity varies from 73.6 to 44.4 % in winter monthsand from 38 to 57 % in summer. The prevailing winddirection is NW to SE.

Sample collection and analysis

A total of 205 daily moist precipitation samples, repre-senting 90 % of the rain events that occurred in theinvestigated area during the period of study, were col-lected at Shoubak weather station located within thestudy area. Two samplers, consisting of a polyethylenefunnel with 26-cm-diameter opening and connected to aneck-screwed polyethylene receiving bottle, with a filterholder between the funnel and the receiving bottle, wereused to collect the samples. Rain collected by the funnelwas filtered by gravity through a 0.45-μm-pore-sizemembrane filter in order to remove the insoluble par-ticles and then collected in the collection bottles. Thefunnel was stored in a clean plastic bag and was broughtout to be mounted on a stand (2.0m in height) just beforea rain. Sampling was done manually on an event basiswhere an event is defined as the span of rain between twodry periods of duration greater than 1 h. Polyethylenebottles and funnels were properly washed with detergent

5716 Environ Monit Assess (2013) 185:5715–5727

and HNO3 and then rinsed with deionized water anddried before use. The collectors (bottles and funnels)were deployed as soon as the rain began and wereretrieved immediately after the rain stopped. Each sam-ple was divided into two parts using two bottles: the firstpart was used for Cl−, NO3

−, SO42−, NH4

+, and pHmeasurements. The receiving bottle connected to thispart was rinsed several times by deionized water anddried before use. The other part was connected to anacid-washed bottle. These bottles were soaked in 20 %HNO3 for approximately 1 day, rinsed several times withdeionized water, and dried before use. After that, samplescollected in acid-washed bottleswere acidified by adding1 ml (5 %) reagent-grade HNO3 to prevent adsorption ofthe tracemetals by the surface of the polyethylene bottlesand to desorb them out of the dust particles (AlKhashman 2005a; Al Momani 2003; Al Momani et al.1995). Wet precipitation from this sampler was used forthe determination of major cations and trace metals (Al-Momani 2003; Al-Khashman 2005a). The precipitationsamples were collected soon after each rainfall and keptin a refrigerator at 4 °C until the time of chemicalanalysis, which was usually performed within 7 daysafter the collection of samples. Precipitation events with

less than 1 mm of rain were discarded. All glassware andpolyethylene bottles were soaked in 20 % HNO3 for1 day and rinsed several times with deionized waterbefore use. The pH values of the collected samples weremeasured for unacidified samples using a 370 JENWAYpH meter equipped with a combination of glass elec-trode. Calibration was always carried out before mea-surement using standard buffer solutions of pH 4.00 and7.00. To avoid junction potential errors due to the lowionic strength of rain samples, pH measurements werecarried out after adjusting the samples to 0.02M of KCL(Nguyen and Valenta 1987). Conductivity measurementswere carried out with a 470 JENWAY conductivity meterwith temperature compensation (Al-Khashman 2005a).The concentration of NH4

+ was determined spectropho-tometrically using Nessler method (Al-Momani 2003).The concentration of bicarbonate was determined bytitration with 0.01 hydrochloric acid usingmethyl orangeas indicator. Major cations, Na+, K+, Ca2+, and Mg2+,were measured by a 800 Varian Flame AtomicAbsorption Spectrophotometer, and major anions, F−,Cl−, NO3

−, and SO42−, were analyzed by 100 Dionex

Ion Chromatography instruments. The system was cali-brated with a certified standard from Dionex. Trace

Fig. 1 Location map of thestudy area

Environ Monit Assess (2013) 185:5715–5727 5717

metals, Fe2+, Al3+, Cu2+, Zn2+, Mn2+, and Pb2+, wereanalyzed with a graphite furnace atomic absorption spec-trophotometer using a Varian model GTA 100 instru-ment. Field blank consisting of 200 ml of deionizedwater was carefully added to the collectors after installa-tion in the field. The sampling bottles were removedimmediately and processed with the same procedure asthat of the precipitation samples. The detection limits ofthe ions, concentrations corresponding to three times thestandard deviation of ten replicate blank level measure-ments, were 0.04, 0.09, 0.03, 0.06, 0.11, 0.04, 0.06, and0.05 μgml− 1 for Cl−, Na+, K+, Mg2+, Ca2+, Cu2+, andFe2+, respectively, and below 0.21μgml− 1 for the rest ofthe trace metals. Precautions were taken in both field andlaboratory work to avoid any contamination of rainwatersamples. Prior to installation, the funnel and collectionbottles were carefully cleaned and dried before use. Anyanalysis of blanks (deionized water) passed through thefunnel to collection bottles were removed and replacedwith others. Pyrex and plastic containers were washedseveral times with soap and deionized water, treated with0.01 M HNO3, and finally rinsed with ultra-pure water.

Results and discussion

Ionic ratio

A total of 205 precipitation samples were collectedduring the rainy periods from October 2006 to May2011 and analyzed for the parameters presented inTable 1. The highest precipitation depths were

obtained during the rainy season of 2006/2007, partic-ularly in December (91.9 mm) followed by January(77.6 mm) (Fig. 2).

A statistical summary of volume-weighted meanmajor ion and heavy metal concentrations in the wetprecipitation samples and their pH and conductivityvalues is presented in Table 1. The ratio of total anionsto that of total cations (∑anions/∑cations) is an indi-cator of completeness of the measured major constit-uents. If all of the major anions and cations areincluded in the measurements, the (∑anions/∑cations)ratio is expected to be unity. Deviation from unityindicated that some of the ions are excluded (Granat1972; Loye-Pilot et al. 1986; Al Momani et al. 1995).The average equivalent sum of anions to that ofcations (∑anions/∑cations) was 0.9±0.2. Linearregression of cation sum versus anion sum gavevalue of R200.94, indicating that the quality of thedata was good.

The average volume-weighted concentrations ofions in the study area compared to those obtained byother researchers are shown in Table 1. The concen-trations of Ca2+ were higher than those reported forIsrael, Turkey, France, India, and China (Salameh andRimawi 1988; Herut et al. 2000; Topcu et al. 2002;Losno et al. 1991; Budhavant et al. 2011 and Huang etal. 2010). The observed high concentration of Ca2+ inthe study area is mainly attributed to the influence ofSaharan dust soil which contains large fractions ofCaCO3. NH4

+ was much higher in precipitation inTurkey compared to Jordan. In Europe for example,NH4

+ dominates all other ions due to the high level of

Table 1 Concentration of majorions in precipitation at the studyarea compared to different loca-tions worldwide

Concentration of ions in μeqL−1, except EC (μscm−1)aHerut et al. (2000)bTopcu et al. (2002)cLosno et al. (1991)dBudhavant et al. (2011)eHuang et al. (2010)

Parameters This study Galilee,Israela

Ankara,Turkeyb

Francec Pune,Indiad

Shenzhen,Chinae

pH 7.07±1.0 – 6.30 5.39 6.7 4.56

EC 85.0±93.0 – – – – –

H+ 0.62±0.6 18.3 – 19.7 – –

Ca2+ 125.4 ±0.1 44.7 71.4 32.7 101.0 35.4

Mg2+ 60.4±0.3 28.0 9.3 35.5 19.7 3.2

Na+ 70.2±0.1 166.0 15.6 261.2 49.3 11.2

K+ 15.2±0.3 3.70 9.8 8.5 6.7 1.7

NH4+ 25.7±0.1 24.3 86.4 24.7 15.8 33.5

HCO3− 121±12.1 – – – – –

Cl− 73.3±0.5 176.3 20.4 357.0 53.4 20.6

NO3− 31.5±0.1 28.0 29.2 28.0 19.4 21.9

SO42− 40.1±0.7 150.3 48.0 42.2 39.5 64.7

5718 Environ Monit Assess (2013) 185:5715–5727

fertilizer use in agricultural activities in addition to thecontribution of industrial activities (Salameh andRimawi 1988; Al Momani et al. 1995; Mouli et al.2005; Al-Khashman 2005b).

Chemical characteristics of precipitation

Wet precipitation samples in the investigated areacontained different concentrations of chemical constitu-ents depending on the amount of rainfall, direction ofrain front, and the length of the dry period between theprecipitation events (Granat 1972). The measured pHvalues ranged from 4.9 to 8.3 with a median value of 7±1, which is in the alkaline range as compared to 5.6 pH

of rainwater at equilibrium with atmospheric CO2. ThepH of rainwater in a clean atmosphere is generallyaround 5.6 due to the dissolution of CO2 in rain droplets(Boubel et al. 1994; Bayraktar and Turalioglu 2005). Asto pH data, the distribution of pH revealed that a largefraction (90 %) of all samples had a pH >5.6 and the rest(10.2 %) had a pH <5.6. Most pH values (55.6 % of allsamples) ranged between 7.5 and 8.5, while only 10.2%of the rainwater samples had pH values between 5.5 and4.5 (Fig. 3).

The observed alkalinity of rainwater is mostly due tothe high loading of particulate matter present in the localatmosphere of the study area. The suspended particulatematter, which is rich in carbonate/bicarbonate of calcium,

0

10

20

30

40

50

60

70

80

90

100

Ra

infa

ll (

mm

)

Oct Nov Dec Jan Feb Mar Apr May

Months

2006

2007

2008

2009

2010

Fig. 2 Monthly rainfall inthe study area during the in-vestigated period (from2006 to 2011)

0

5

10

15

20

25

30

Fre

qu

en

cy

2006 2007 2008 2009 2010

Years

4.5-5.5 5.5-6.5

6.5-7.5 7.5-8.5

Fig. 3 Frequency distribu-tion of pH measurements inrainwater samples

Environ Monit Assess (2013) 185:5715–5727 5719

buffers the acidity of rainwater (Özsoy and Örnektekin2009). The electrical conductivity (EC) of the precipita-tion samples was found to be highly variable within arange of 5–350 μS cm−1. The mean EC value measuredwas 85±93 μS cm−1, with the highest value of 93.7 μScm−1 measured in 2009, which was lower than that of thewestern site of Jordan (95±97) (Al-Khashman 2009). Avery high positive correlation (R200.89, p<0.05) wasfound between conductivity and calcium concentration.The rainwater samples with relatively high concentra-tions of calcite minerals and carbonate materials had veryhigh conductivity (130 μS cm−1), most likely due to thehigh content of soluble solids, high ion adsorption capac-ity of carbonate materials and dust surfaces, and adsorp-tion–desorption process taking place between the solidand liquid phases (Özsoy and Örnektekin 2009).

The percentage of ions to total ion mass in wetprecipitation samples is shown in Fig. 4. These resultsclearly show that the mean concentration of ionicspecies in precipitation followed the order ofHCO3

−>Cl->SO42−>NO3

− for anions and Ca2+ >Na+>Mg2+>NH4

+>K+ for cations, which is typicalfor the urban environment of arid and semiarid areas(Jain et al. 2000; Avila and Roda 2002; Kulshrestha etal. 2003; Anatolaki and Tsitouridou 2009). Amongthese ions, HCO3

−, Ca2+, Cl−, Na+, Mg2+, and SO42−

were the dominant ions accounting for almost 86 % ofthe total ions. HCO3

− was found to have the highestcontribution among all ions, representing 22 % of thetotal ion mass. While the highest value of bicarbonatewas measured during warmer dusty storms, the lowestvalue of bicarbonate (20 μeq L−1) was measured dur-ing the rainy period, particularly in January. This ismainly attributed to the fact that intensive precipitationduring the cold months effectively scavenged the dustfrom the atmosphere (Fig. 5).

The SO42− concentration was found to be high

(40 μeq L−1) and contributed almost 7 % to thetotal ions mass. One possible source leading to thehigh concentration of sulfate in rainwater samplesis the washout sea salt and the soil dust comingfrom North Africa and deserts around the countrycontaining large fractions of calcite, dolomite, gyp-sum, halite, and clay minerals (Foner and Ganor1992). Another possible source of SO4

2− in the atmo-sphere is coming from fuel combustion during the coldwinter months, releasing a sufficient amount of SO2 intothe atmosphere (Al-Khashman 2005a).

The yearly mean values of SO42−, NO3

−, NH4+, and

Ca2+ concentrations during five rainy seasons are pre-sented in Fig. 5. Chloride accounts for 13 % of thetotal mass of ions in rainwater samples. The highvalues of Cl− in rainwater samples were due to theSaharan dust storms in which the region was affectedduring the spring season. Mg2+ ions contribute almost11 % of the total ions mass. The observed Mg2+ valuesin rainwater samples generally resulted from both seasalt and dust particles in the atmosphere.

The mean concentrations of Na+ and K+ ions ac-count for 12 and 3 % of the total ion mass, respective-ly. The origins of Na+ and K+ were mainly dust seasalts, the aerosols of the Dead Sea and MediterraneanSea, and polar depressions that affected Jordan duringthe rainy seasons (Foner and Ganor 1992).

NO3− ion has a smaller contribution compared

to Cl− and SO42−. The main sources of NO3

− inthe rainwater samples are industries located towest and north of the investigated area such as apotash factory, cement factory, phosphate mines insouth Jordan, and airborne fertilizer particles.However, motor vehicle emissions make a signifi-cant contribution during the dry season when

Fig. 4 Percentage of ions tototal ion mass in wet pre-cipitation samples

5720 Environ Monit Assess (2013) 185:5715–5727

transport and tourist vehicle traffic increased (AlMomani et al. 1995). Additionally, agricultural ac-tivities in Wadi Araba and the Ghore area, inaddition to the intense thunderstorms, are otherpotential sources that cause an increase in NO3

−

concentration in some rainwater samples.

pH distribution and acidity neutralization

The pH of the collected rain samples ranged from 4.50to 8.24, with a mean value of 7±1. The relatively highmean pH value measured in this area is due to theneutralization of acidity in precipitation by carbonates.Neutralization is usually reported in the Mediterraneanregion, where the composition of rainwater is stronglyaffected by the alkaline minerals in Saharan dust (Loye-Pilot et al. 1986; Salameh and Rimawi 1988; Salameh etal. 1991; AlMomani 2003). In general, rainwater acidityis mainly due to H2SO4 and HNO3, while HCl, HF, andorganic acids are considered as negligible acidity con-tributors compared to H2SO4 and HNO3 (Anatolaki andTsitouridou 2009). To examine whether the acidity isneutralized or not, the fractional acidity (FA) was com-puted as FA0[H+]/([SO4

2−]+[NO3−]) according to

Balasubramanian et al. (2001). If this ratio (FA) is 1, itis considered that the acidity generated by these strongacids is not neutralized at all. The annual average valuewas 0.2±0.1, which means that approximately 80 %acidity was neutralized by alkaline constituents. Therelative contribution of SO4

2− to rain acidity was calcu-lated using equivalent ratio [NO3

−]/([NO3−] + [SO4

2−])The annual average was 0.43, reflecting that about 43 %

of the acidity of rain was due to NO3− and the remaining

57 % due to SO42− (Safai et al. 2004). The interaction

between acidic and alkaline constituents incorporated inrain, and thus the effect of the latter in the neutralizationprocess can be confirmed by means of neutralizationfactors (NF), which are calculated using the formulasuggested by Possanzini et al. (1988) and Kulshresthaet al. (1995) as follows:

NFXI ¼ Xi½ � SO42�� �þ NO3

�½ ��

where [Xi] is the concentration of the alkaline compo-nent: Ca2+, Mg2+, K+ , Na+, and NH4

+, expressed inμeq L−1. The NF values for Ca2+, NH4

+, Mg2+, K+, andNa+ in rainwater samples of this study were 1.75, 0.84,0.21, 0.98, and 0.36 respectively, showing that Ca2+,Mg2+, and Na+ were the dominant neutralization compo-nents in the rainwater, whereas the neutralization by crustcomponents such as K+ and NH4

+ was less important.To assess the balance between acidity and alka-

linity, the ratio of neutralizing potential (NP) toacidifying potential (AP) was computed asNP/AP 0 ([Ca2+] + [NH4

+])/([SO42−] + [NO3

−])(Safai et al. 2004). The NP/AP value was 2.11,which is higher than that recorded in South China(0.80) (Cao et al. 2009) and India (1.33) (Safai etal. 2004), indicating the overall dominance of al-kaline constituents that prevented the acidificationof rainwater. However, the decreasing trend of thisratio from 2.11 (rainy season 2006) to 1.83 (rainyseason 2011) showed that the neutralization capac-ity is declining.

0

20

40

60

80

100

120

140

160

180

Ca Mg Na K NH4 HCO3 Cl NO3 SO4

pp

m

ions

2006

2007

2008

2009

2010

Fig. 5 The yearly meanconcentrations of ions inrainwater samples

Environ Monit Assess (2013) 185:5715–5727 5721

SO42−/NO3

− Ratio

The SO42−/NO3

− ratio can be used to indicate thecontribution of anthropogenic sources in urban areas(Migliavacca et al. 2005). The results obtained in thisstudy are shown in Table 2 and are compared withthose reported in other locations. They show that theSO4

2−/NO3− ratio was lower than those found in other

studies such as in Guaiba, Galilee, Italy, and Spain.This might be due to the fact that the sites are located

beside or in industrialized urban areas. SO42−/NO3

−

are conventional acidic ions in wet precipitation, whilethe relative contribution of these ions to the acidity ofrainwater is variable. Until recently, the contributionof H2SO4 in atmospheric precipitation samples wasestimated at 60–70 % and that of HNO3 at 30–40 %(Al Momani et al. 1995; Tuncer et al. 2001;Migliavacca et al. 2005; Al-Khashman 2005b).

Determination of chemical sources

Relationships between ionic species were determined bycorrelation analysis. Table 3 gives the linear correlationcoefficients computed from 205 samples. As shownfrom the inspection of these values, there is no associa-tion between free acidity and SO4

2− and NO3−. This

suggests that SO42− and NO3

− salts in wet precipitationoriginated from the ionization of sulfate and nitrate salts,which are produced from neutralizing processes.

A strong correlation was found between NO3−

and SO42− (rNO3

−/SO42−c0ratio can be used to

indicate the contribution 0.85). The reason for thepresence of nitrate and sulfate in high quantitymight be due to the accumulation of these ionsin the upper atmosphere that is subsequently beingwashed out during the rainy season. In addition,industrial and agricultural activities located to thewest of the investigated area may contribute inincreasing NO3

− and SO42− concentrations during

summer and autumn.

Table 2 SO42−/NO3

− comparison ratio at various locations inthe world

Locations SO42−/NO3

− References

Present study 1.27

Italy 3.10 Le Bolloch and Guerzoni (1995)

Spain 2.22 Avila and Alarcon (1999)

Galilee 5.37 Herut et al. (2000)

Singapore 3.50 Balasubramanian et al. (2001)

Ankara 1.60 Topcu et al. (2002)

Guaiba 8.70 Migliavacca et al. (2005)

Jordan 1.91 Al-Khashman (2005b)

China 1.49 Li et al. (2007)

Romania 1.56 Arsene et al. (2007)

Guangzhou 3.05 Cao et al. (2009)

Taiwan 1.40 Cheng and You (2010)

Granada 1.29 Calvo et al. (2010)

Table 3 Spearman's rank correlation matrix for rainwater samples (n0205); all values are in μeq−1L except the conductivity (μscm−1)

Var. pH EC HCO3− Cl− Ca2+ Mg2+ Na+ K+ NO3

− SO42− NH4

+

pH 1.00

EC 0.34 1.00

HCO3− 0.06 0.34 1.00

Cl− −0.20 0.22 0.51 1.00

Ca2+ −0.33 0.15 0.55 0.79 1.00

Mg2+ −0.18 0.28 0.62 0.82 0.79 1.00

Na+ 0.19 0.41 0.73 0.33 0.18 0.54 1.00

K+ 0.10 0.25 −0.15 0.18 0.11 −0.14 0.19 1.00

NO3 −0.15 0.20 0.18 0.72 0.66 0.71 0.17 0.08 1.00

SO42− −0.08 0.38 0.40 0.74 0.70 0.79 0.41 0.14 0.85 1.00

NH4+ 0.27 0.32 −0.18 0.30 0.12 −0.15 0.07 0.10 0.22 0.20 1.00

Italicized text indicates strong correlations: 0.60–1.000strong correlation, 0.50–0.590moderate, 0.40–0.490weak, 0.00–0.390little orno association

5722 Environ Monit Assess (2013) 185:5715–5727

Strong correlations of HCO3− with Na+ and Mg2+

(rHCO3−/Na+ratio can be used to indicate the contri-

bution 0ratio can be used to indicate the contribution0.73; rHCO3

−/Mg2+ratio can be used to indicate thecontribution 0ratio can be used to indicate the contri-bution 0.62) were found, supporting as well the as-sumption of neutralization with soil dust and sea spray.There is a strong correlation of Cl− with Mg2+, Ca2+,SO4

2−, and NO3− (rCl−/Mg2+ 0 0.82; rCl−/Ca2+00.79;

rCl−/SO42−00.74; rCl−/NO3

−00.72). Ca2+ is well cor-related with Mg2+, SO4

2−, and NO3− (rCa2+/Mg2+0

0.79; rCa2+/SO42−00.70; rCa2+/NO3−00.66), sug-

gesting the presence of a natural contribution to theobserved concentrations of these ions. The Mg2+ con-centration is strongly correlated with NO3

− and SO42−

(rMg2+/SO42−00.79; rMg2+/NO3

−00.71).

Statistical analysis

The relationship between concentrations was deter-mined with factor analysis. Factor analysis allows theidentification of a small number of factors that couldexplain the variability of most of the original data(Möller et al. 2005). Factor analysis using methods

of principal component analysis was applied to helpidentify the source of ions in the rainwater samples byusing factor extraction with Eigenvalue larger than 1after varimax rotation.

The results of statistical analysis are given inTable 4. The loadings having a value greater than0.70 are marked in italics. Factor 1 accounts for29.6 % of the total variance and has high loading forCa2+, K+, NH4

+, HCO3−, Fe, Al, and Cu in decreasing

order. This factor is associated with soil and sea saltsources and has been identified as “crustal factor”.Factor 2 accounts for approximately 24.8 % of thetotal variance and has high loadings for Cl−, Na+,and Mg2+ and moderate loadings for K+, SO4

2−, andCa2+. This factor is associated with sea salt sourcesand has been identified as “marine factor”. The asso-ciation of sodium and chloride in factor 1 indicates thepresence of sea salts arriving in masses of polar sea air(Lee et al. 2000; Mello 2001). Mg2+ and Ca2+ arefrequently found in soil and dust (or particulate matter)as well as fallout of Saharan dust, and they contributeto neutralization reactions that occur in atmosphericprecipitation (Saxena et al. 1996; Migliavacca et al.2005; Ganor et al. 1991). Factor 3 showed high load-ings of the Pb and Zn and moderate loading of H+,explaining about 13.8 % of the total variance. Thenitrate and moderate NH4

+ found in atmospheric wetdeposition may come from several sources, includingthe volatilization of animal residues, human excre-ments, and natural loss by plants, biomass burning,and industrial activities, such as the use of fertilizers inagricultural activities (Migliavacca et al. 2005). Basedon statistical analysis, both Pb and Zn are character-istics of road traffic emissions (Al Momani 2003).

The mean mass contribution from identified sour-ces is presented in Table 5. It can be seen that forrainwater samples the marine source delivers the

Table 4 Factor analysis of chemical constituents in wetprecipitation

Parameters Factor 1 Factor 2 Factor 3

H+ 0.52 0.52

Ca2+ 0.81

Mg2+ 0.84

Na+ 0.80

K+ 0.66 0.50

NH4+ 0.69 0.51

HCO3− 0.77

Cl− 0.88

NO3− 0.78

SO42− 0.68

Fe 0.85

Al 0.89

Mn 0.82

Cu 0.84

Pb 0.88

Zn 0.89

Total variance (%) 29.6 24.8 13.8

Italicized entries indicate loadings having a value greater than0.70

Table 5 Mean mass contribution from identified sources forwet precipitation

Source Meancontribution

Percentage of totalpredicted mass

Soil dust (crustal) 441.1±11.3 63.6

Anthropogenic 137.3±11.8 19.5

Sea spray (marine) 122.7±14.2 17.1

Total predicted mass 701.1±45.3 –

μeq L−1 for the wet precipitation parameters

Environ Monit Assess (2013) 185:5715–5727 5723

dominant quantity of potassium, sodium, and chloride;the anthropogenic source emits mostly mainly ammoni-um and nitrate with additional contribution of chloridesand sulfates. The soil dust (Saharan soil dust) sourcecontributes bicarbonate, calcium, and magnesium withadditional contribution of chloride and sulfate.

Trace metals

The statistical analysis of trace metal values in rain-water samples collected within the study area duringthe rainy season is presented in Table 6. The meanvalues for Fe, Al, Cu, Pb, and Zn were 87, 115, 40,35.51, 39.1, and 32.87 μg L−1 respectively. The vari-ation of concentration of these metals in rainwatersamples can be explained by the scavenging of pollu-tants (Al-Khashman 2005b). The variation in the val-ues of trace metals between different rainfall events is

likely to be related to the source of pollutantemissions. The highest concentrations of metalswere measured at the beginning of a rainfall eventafter extended periods of no rain, while low valuesof metals were measured when rain continued forseveral days.

The relative abundance in rainwater is Al > Fe >Pb > Cu > Zn > Mn, which depends upon theirevaporation rate, relative concentration of metals inrainwater samples, and solubility of the metal solids(Fig. 6). The maximum concentrations appeared in thebeginning of the rainy season because of the fact thatthere is a large amount of pollutants accumulated inthe atmosphere due to local emissions and long-rangetransport. Metal concentrations in rainwater had agreat variability according to the origin and movementof the atmospheric depression, metrological condi-tions, and the amount of rainfall.

Table 6 Concentrations of trace metals in wet precipitation (μg L−1)

Element This study Worldwide reviewa Western Massachb Athensc Mersind Okinawae

Fe 87.0±93.8 – 65 4.38 3.2 2.4

Al 115.0±115.8 – 53 – 6.5 2.7

Mn 20.0±23.7 0.5 0.3 0.2 0.5 –

Cu 35.5±26.8 5.4 0.9 15.4 1.6 1.3

Pb 39.2±42.4 12.0 4.5 0.8 5.0 –

Zn 32.9±28.1 36.0 3.7 33.5 36.9 9.2

Concentration of metals in μg L−1

a Galloway et al. (1982)b Dasch and Wolff (1989)c Kanellopoulou (2001)d Özsoy and Örnektekin (2009)e Vuai and Tokuyama (2011)

Fe28%

AI37%

Mn1%

Cu11%

Pb13%

Zn10%

Fig. 6 The percent distribu-tion of metals in differentwet precipitation samples

5724 Environ Monit Assess (2013) 185:5715–5727

The highest concentration of metals occurred dur-ing the period from January to March, which is possi-bly due to the higher emission of these pollutantsduring the cold rainy season. Strong correlations wereobserved between Cu and Pb (R200.802) and betweenPb and Zn (R200.789). The high concentrations ofmetal in wet precipitation may be attributed to thelong-range atmospheric transport of anthropogenicemissions coming from other parts of Europe and localpoint sources of atmospheric pollution as well as thesoil dust which affect the composition of wet atmo-spheric deposition.

Conclusions

This study is essential for establishing a data base aboutrainwater quality around one of the most importantwatersheds in the southern region of Jordan. The pHof rainwater samples ranged from 4.9 to 8.3, with anaverage of 7±1, which is in the alkaline range as com-pared to 5.6 pH of rainwater at equilibrium with atmo-spheric CO2. The results obtained revealed that therainwater in the area is alkaline, while the acidity inrainwater is largely neutralized by Ca2+ and Mg2+,whereas NH4

+ played a minor role. The major ionsand their concentrations in rainwater followed the orderof HCO3 > Ca2+ > Cl− > Na+ >Mg2+ > SO4

2− > NO3− >

NH4+ > K+. Sulfate and nitrate were the major acidify-

ing ions in the rainwater of the study area.The chemical composition of rainwater is influenced

by either local condition such as the presence of theDeadSea, agricultural activities in the Ghore area located atwestern part of the study area, and/or remote sites asso-ciated with depressions rich in calcite, dolomite, andgypsum and polar and Mediterranean depressions richin sulfate and nitrate ions. There is a strong correlationbetween Ca2+ and Mg2+, Ca2+ and HCO3

−, Ca2+ andCl−, Ca2+ and SO4

2−, and NO3− and SO4

2−. Other mod-erate correlations were observed betweenK+ and Cl− andbetween NH4

+ and NO3− and SO4

2−. Among the ions,HCO3

− makes the highest contribution, followed by Ca2+, Cl− and SO4

2−, indicating the incorporation of soil dustinto the rain samples, which reflects a major crustalinfluence. The relatively moderate concentration ofNH4

+ observed at the study area is suspected to be dueto the surrounding agricultural activity. This agriculturalactivity was found to be important not only in winter andspring but also in summer and autumn.

The use of factor analysis facilitates the interpretationof the rainwater chemistry characterization, highlightingthe influence of the anthropogenic sources in the studyarea. The results of this study are related to varioussources such as soil dust, sea salts spray, agriculturalactivities, and combustion products. The concentrationsof trace metals (Al > Fe > Pb > Cu > Zn > Mn)determined in the rainwater samples were relativelylow. The main sources of trace metals in rainwater wereanthropogenic sources. The results of metal loadingssuggest that it is necessary to continuously monitormetal deposition fluxes on a long-term basis to evaluatethe annual and seasonal atmospheric deposition.

References

Al-Khashman, O. A. (2009). Chemical characteristics of rain-water collected at a western site of Jordan. AtmosphericResearch, 91((1), 53–61.

Al-Khashman, O. (2005a). Ionic composition of wet precipita-tion in the Petra region, Jordan. Atmospheric Research, 78,1–12.

Al-Khashman, O. (2005b). Study of chemical composition inwet atmospheric precipitation in Eshidiya area, Jordan.Atmospheric Environment, 39, 6175–6183.

Al Momani, I. (2003). Trace elements in atmospheric precipita-tion at northern Jordan measured by ICP-MS: acidity andpossible sources. Atmospheric Environment, 37, 4507–4515.

Al-Momani, I., Momani, K., & Jaradat, Q. (2000). Chemicalcomposition of wet precipitation in Irbid. Journal ofAtmospheric Chemistry, 35, 47–57.

Al Momani, I., Tuncel, S., Eler, U., Ortel, E., Sirin, G., &Tuncel, G. (1995). Major ion composition of wet and drydeposition in the eastern Mediterranean Basin. The Scienceof the Total Environment, 164, 75–85.

Anatolaki, C., & Tsitouridou, R. (2009). Relationship betweenacidity and ionic composition of wet precipitation. A twoyears study at an urban site, Thessaloniki, Greece.Atmospheric Research, 92(1), 100–113.

Arsene, C., Olariu, R. I., & Mihalopoulos, N. (2007). Chemicalcomposition of rainwater in the northeastern Romania, Iasiregion (2003–2006). Atmospheric Environment, 41, 9452–9467.

Avila, A., & Alarcon, M. (1999). Relationship betweenprecipitation chemistry and metrological situations ata rural site in NE Spain. Atmospheric Environment, 33,1663–1667.

Avila, A., & Roda, F. (2002). Assessing decadal changes inrainwater alkalinity at a rural Mediterranean site in theMontseny Mountains (NE Spain). AtmosphericEnvironment, 36, 2881–2890.

Balasubramanian, R., Victor, T., & Chun, N. (2001). Chemicaland statistical analysis of precipitation in Singapore. Water,Air, and Soil Pollution, 130, 451–456.

Environ Monit Assess (2013) 185:5715–5727 5725

Bayraktar, H., & Turalioglu, F. S. (2005). Composition of wetand bulk deposition in Erzurum, Turkey. Chemosphere, 59,1537–1546.

Bergametti, G., Dutot, A. L., Buart-Menard, P., Losno, R., &Remoudaki, E. (1989). Seasonal variability of elementalcomposition of atmospheric aerosol particles over the northwestern Mediterranean. Tellus, 41B, 353–361.

Boubel, R. W., Fox, D. L., Tuner, D. B., & Stern, A. C. (1994).Fundamentals of air pollution. San Diego: Academic.

Budhavant, K. B., Rao, P. S. P., Safai, P. D., & Ali, K. (2011).Influence of local sources on rainwater chemistry overPune region, India. Atmospheric Research, 100, 121–131.

Calvo, A. I., Olmo, F. J., Lyamani, H., Arboledas, L. A., Castro,A., Fernandez, M., et al. (2010). Chemical composition ofwet precipitation at the background EMEP station inViznar (Granada, Spain) (2002–2006). AtmosphericResearch., 96, 408–420.

Cao, Y. Z., Wang, S. H., Zhang, G., & Luo, J. (2009). Chemicalcharacteristics of wet precipitation at an urban site ofGuangzhou, south China. Atmospheric Research, 94,462–469.

Cheng, M. C., & You, C. F. (2010). Sources of major ions andheavy metals in rainwater associated with typhoon eventsin southwestern Taiwan. Journal of GeochemicalExploration, 105, 106–116.

Das, N., Das, R., Chaudhury, G. R., & Das, S. N. (2010).Chemical composition of precipitation at background level.Atmospheric Research, 95, 108–113.

Dash, J. M., & Wolff, G. (1989). Trace inorganic species inprecipitation and their potential use in source appor-tionment studies. Water, Air, and Soil Pollution, 43,401–412.

Department of Meteorology. (2010). Internal report. Jordan:Amman.

Foner, H. A., & Ganor, E. (1992). The chemical and mineral-ogical composition of some urban atmospheric aerosols inIsrael. Atmospheric Environment, 26, 125–133.

Galloway, J. N., Thornton, J. D., Norton, S. A., Volchok, H. L.,& McLean, R. A. (1982). Trace metals in atmosphericdeposition: a review and assessment. AtmosphericEnvironment, 16, 1677–1700.

Ganor, E., Foner, H. A., Brenner, J., Neeman, E., & Lavi, N.(1991). The chemical composition of aerosols setting inIsrael following dust storms. Atmospheric Environment,25A, 2665–2670.

Granat, L. (1972). On the relation between pH and the chemicalcomposition in atmospheric precipitation. Tellus, 6, 550–560.

Gullu, G., Olmez, I., Aygun, S., & Tuncel, G. (1998).Atmospheric trace elements concentrations over theeastern Mediterranean Sea: factors affecting temporalvariability. Journal of Geophysical Research, 103,21943–21954.

Herut, B., Starinsky, A., Katz, A., & Rosenfeld, D. (2000).Relationship between the acidity and the chemical compo-sition of rainwater and climatological conditions a long atransition zone between large deserts and Mediterraneanclimate, Israel. Atmospheric Environment, 34, 1281–1292.

Huang, X. F., Xiang, L., Ling, Y. H., Ning, F., Min, H., Yu, W.,et al. (2010). 5-year study of rainwater chemistry in acoastal mega-city in south China. Atmospheric Research,97, 185–193.

Jain, M., Kulshrestha, U. C., Sarkar, A. K., & Parashar, D. C.(2000). Influence of crustal aerosols on wet deposition aturban and rural sites in India. Atmospheric Environment,34, 5129–5137.

Kanellopoulou, E. A. (2001). Determination of heavy metals inwet deposition of Athens. Global Nest: The InternationalJournal, 3(1), 45–50.

Kubilay, N., & Saydam, A. C. (1995). Trace elements in theatmospheric particulates over eastern Mediterranean; con-centrations, sources and temporal variability. AtmosphericEnvironment, 29, 2289–2300.

Kulshrestha, U., Monika, T., Kulshrestha, M., Sekar, R., &Vairamani, M. (2003). Chemical characteristics of rainwa-ter at an urban site of south central India. AtmosphericEnvironment, 37, 3019–3026.

Kulshrestha, U. C., Sarkar, A. K., Srivastava, S. S., & Parashar, D.C. (1995). Wet-only and bulk deposition studies at NewDelhi (India).Water, Air, and Soil Pollution, 85, 2137–2142.

Le Bolloch, O., & Guerzoni, S. (1995). Acid and alkalinedeposition in precipitation on the western coast ofSardinia, central Mediterranean (40°N, 8°E). Water, Air,and Soil Pollution, 85, 2155–2160.

Lee, B. K., Hong, S. H., Lee, D. S. (2000). Chemical composi-tion and wet deposition of major ions on the Koreanpeninsula. Atmospheric Environment 34, 563–572.

Li, C., Kang, S., Zhang, Q., & Kaspari, S. (2007). Major ioniccomposition of precipitation in the Nam Co region, CentralTibetan Plateau. Atmospheric Research, 85, 351–360.

Losno, R., Bergametti, G., Carlier, P., & Mouvier, G. (1991).Major ions in marine rainwater with attention to sources ofalkaline and acidic species. Atmospheric Environment, 25A(3/4), 763–770.

Loye-Pilot, M. D., Martin, J. M., & Morelli, J. (1986). Influenceof Saharan dust on the rain acidity and atmospheric input tothe Mediterranean. Nature, 321, 427–428.

Mello, W. Z. (2001). Precipitation chemistry in the coast ofthe Metropolitan region of Rio de Janeiro, Brazil.Environmental Pollution, 114, 235–242.

Migliavacca, D., Teixeira, E. C., Wiegand, F., Machado, A., &Sanchez, J. (2005). Atmospheric precipitation and chemi-cal composition of an urban site, Guaiba hydrographicbasin, Brazil. Atmospheric Environment, 39, 1829–1844.

Mouli, P., Mohan, S., & Reddy, S. (2005). Rainwater chemistryat a regional representative urban site: influence of terres-trial sources of ionic composition. AtmosphericEnvironment, 39, 999–1008.

Möller, A., Muller, H. W., Abdullah, A., Abdelgwad, G., &Utermann, J. (2005). Urban soil pollution inDamascus, Syria: concentrations and pattern of heavymetals in the soils of the Damascus Ghouta.Geoderma, 124, 63–71.

Munger, J. (1982). Chemistry of atmospheric precipitation innorth-central United States: influence of sulfate, nitrate,ammonia and calcareous soil particulate. AtmosphericEnvironment, 16, 1633–1645.

Nguyen, V. D., & Valenta, P. (1987). Electronic determination ofthe pH of atmospheric precipitation. Fresenius' Journal ofAnalytical Chemistry, 327, 253–260.

Özsoy, T., & Örnektekin, S. (2009). Trace elements in urban andsuburban rainfall, Mersin, Northeastern Mediterranean.Atmospheric Research, 94, 203–219.

5726 Environ Monit Assess (2013) 185:5715–5727

Possanzini, M., Buttini, P., & Dipalo, V. (1988). Characterizationof a rural area in terms of dry andwet deposition. The Scienceof the Total Environment, 74, 111–120.

Safai, P. D., Rao, P. S. P., Momin, G. A., Ali, K., Chate, D. M.,& Praveen, P. S. (2004). Chemical composition of precip-itation during 1984–2002 at Pune, India. AtmosphericEnvironment, 38, 1705–1714.

Sakihama, H., Ishiki, M., & Tokuyama, A. (2008). Chemicalcharacteristics of precipitation in Okinawa, Island, Japan.Atmospheric Environment, 42, 2320–2335.

Salameh, E., & Rimawi, O. (1988). Hydrochemistry of precip-itation of Northern Jordan. Internal Journal ofEnvironmental Studies, 32, 203–216.

Salameh, E., Rimawi, O., & Abu Moghli, I. (1991). Precipitationwater quality in Jordan. Bulletin, Water Research and StudyCenter, 16, 98pp.

Saxena, A., Kulshrestha, U. C., Kumar, N., Kumari, K. M., &Srivastava, S. S. (1996). Characterization of precipitationat Agra. Atmospheric Environment, 30(20), 3405–3412.

Schuurkes, J., Maenen, M., & Roelofs, J. (1988). Chemicalcharacteristics of precipitation in NH3

− affected areas.Atmospheric Environment, 22, 1689–1698.

Shehdeh, N. (1991). The climate of Jordan. Amman: Al Basher.Topcu, S., Incecik, S., & Atimtay, A. T. (2002). Chemical

composition of rainwater at EMEP station in Ankara,Turkey. Atmospheric Research, 65, 77–92.

Tuncer, B., Bayer, B., Yesilyurt, C., & Tuncel, G. (2001). Ioniccomposition of precipitation at the central Anatolia,Turkey. Atmospheric Environment, 35, 5989–6002.

Vuai, S. A., & Tokuyama, A. (2011). Trend of trace metals inprecipitation around Okinawa Island, Japan. AtmosphericResearch, 99, 80–84.

Environ Monit Assess (2013) 185:5715–5727 5727