Malaysian Journal of Analytical Sciences, Vol 27 No 5 (2023): 971 – 979

 

ASSESSMENT OF IONIC SPECIES IN RAINWATER TOWARD pH VARIABILITY BETWEEN HIGHLANDS AND LOWLAND IN MALAYSIA

 

(Penilaian Spesis Ionik Dalam Air Hujan Terhadap Kepelbagaian pH

di Antara Tanah Tinggi dan Tanah Rendah di Malaysia)

 

Puteri Marlini Zaini1, Ku Mohd Kalkausar Ku Yusof1*, and Siti Kamilah Che Soh1,

and Samsuri Abdullah2

 

1Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

 2Faculty of Ocean Engineering Technology and Informatics, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

 

*Corresponding author: kukausar@umt.edu.my

 

 

Received: 23 June 2023; Accepted: 9 August 2023; Published:  30 October 2023

 

 

Abstract

This study investigated the variability of ionic species and pH in rainwater chemistry during wet fallout events in Highlands (Cameron Highlands, CH) and lowlands (Petaling Jaya, PJ) in 2019. A total of 1,040 datasets were obtained from the Malaysia Meteorological Department. Descriptive analysis, Mann-Whitney U test, Spearman correlation test, and discriminant analysis were employed. The selected variables included pH, H+, Na+, K+, Ca2+, Mn2+, Zn2+, Cl-, NO3-, and SO42-. Mn2+ exhibited a significant difference (p <0.05) between CH and PJ. Rainfall at PJ was more acidic due to higher concentrations of Cl-, SO42-, and NO3-. pH in CH showed a strong positive correlation with Na+, K+, and Ca2+ as compared to PJ, attributed to atmospheric neutralizing reactions between acids (HNO3 and H2SO4) and alkaline compounds (CaCO3, NaCl, and KNO3) present in suspended fine particles during wet fallout. Discriminant analysis, by using the confusion matrix, demonstrated significant differences in the overall performances of anions, cations, and pH in rainwater chemistry between CH and PJ, achieving 94.32% classification accuracy. This study highlighted the variability of ionic species and pH in rainwater chemistry between highlands and lowland areas. The findings contributed to understanding atmospheric heterogeneous reactions and factors that influenced rainwater chemistry at different geographic locations.

 

Keywords: wet fall-out, ionic species, statistical analysis, Petaling Jaya, Cameron Highlands

 

Abstrak

Kajian ini mengkaji kebolehubahan spesies ionik dan pH dalam kimia air hujan semasa berlakunya hujan di tanah tinggi (Cameron Highlands, CH) dan tanah rendah (Petaling Jaya, PJ) pada tahun 2019. Sebanyak 1,040 set data diperoleh daripada Jabatan Meteorologi Malaysia. Analisis deskriptif, ujian Mann-Whitney U, ujian korelasi Spearman, dan analisis diskriminasi telah digunakan. Pemboleh ubah yang terpilih termasuk pH, H+, Na+, K+, Ca2+, Mn2+, Zn2+, Cl-, NO3-, dan SO42-. Mn2+ menunjukkan perbezaan yang signifikan (p <0.05) antara CH dengan PJ. Hujan di PJ lebih berasid sebab disumbangkan oleh kepekatan Cl-,   SO42-, dan NO3- yang lebih tinggi. pH di CH menunjukkan korelasi positif yang kuat dengan Na+, K+, dan Ca2+ berbanding dengan PJ, disebabkan oleh tindak balas peneutralan atmosfera antara asid (HNO3 dan H2SO4) dengan sebatian alkali (CaCO3, NaCl, dan KNO3) yang terdapat dalam zarah halus yang terampai semasa hujan. Analisis diskriminasi, menggunakan matriks kekeliruan, menunjukkan perbezaan ketara dalam prestasi keseluruhan anion, kation, dan pH dalam kimia air hujan antara CH dengan PJ, mencapai ketepatan pengelasan 94.32%. Kesimpulannya, kajian ini mengetengahkan kebolehubahan spesies ion dan pH dalam kimia air hujan antara kawasan tanah tinggi ddengan tanah rendah. Penemuan ini menyumbang kepada pemahaman tindak balas heterogen atmosfera dan faktor yang mempengaruhi kimia air hujan di lokasi geografi yang berbeza.

 

Kata kunci: hujan, spesies ionik, analisis statistik, Petaling Jaya, Cameron Highlands

 

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