Payus C M, Jikilim C, Sentian J
Institute for the Future Initiatives, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8654, Japan.
Faculty of Science & Natural Resources, Universiti Malaysia Sabah, 88400, Kota Kinabalu, Sabah, Malaysia.
Heliyon. 2020 Sep 21;6(9):e04997. doi: 10.1016/j.heliyon.2020.e04997. eCollection 2020 Sep.
The purposes of this research were to study the characteristics chemistry of pH, anions and cations in rainwater, and to identify the possible sources that contributing to the acid precipitation during southwest monsoon season with occurrence of extreme drought event. During the southwest monsoon season, it normally occurs along with haze phenomenon that every year will hit Southeast Asia. This condition will aggravate with high acidic particles in the atmosphere due to the prolonged drought. The analysed parameters which involved pH, anions (NO , SO and Cl) and cations (Ca, Mg, Na and K) were analysed using pH meter, Hach DR 2800, argentometric method and ICP-OES. From the findings, it showed that acid rain occurred during the southwest monsoon season with the range of pH values from 4.95 ± 0.13 to 6.40 ± 0.03 and the total average of pH 5.71 ± 0.32. Anions NO , SO and Cl were found to be the dominant compositions of the acid rain occurrences with higher concentrations detected. In overall, rural area recorded with higher acidity of precipitation at total average of pH 5.54 ± 0.39 compared to urban area at pH 5.77 ± 0.26. Rural area surprisingly recorded higher frequency occurrences of acid rain with pH lesser than 5.6 and below compared to urban area. As for public health and safety, all rainwater samples during the acid rain event were found exceeded the allowable limits of NWQS and WHO standards, that shown not suitable for skin contact, recreational purposes even for drinking purposes.
本研究的目的是研究雨水的pH值、阴离子和阳离子的化学特性，并确定在西南季风季节发生极端干旱事件期间导致酸雨的可能来源。在西南季风季节，通常会伴随着每年都会袭击东南亚的雾霾现象。由于长期干旱，大气中高酸性颗粒物会使这种情况更加恶化。使用pH计、哈希DR 2800、银量法和电感耦合等离子体发射光谱仪（ICP-OES）对涉及pH值、阴离子（NO 、SO 和Cl）和阳离子（Ca、Mg、Na和K）的分析参数进行分析。研究结果表明，西南季风季节出现了酸雨，pH值范围为4.95±0.13至6.40±0.03，pH值总平均值为5.71±0.32。发现阴离子NO 、SO 和Cl是酸雨发生的主要成分，检测到的浓度较高。总体而言，农村地区降水酸度较高，pH值总平均值为5.54±0.39，而城市地区为5.77±0.26。令人惊讶的是，农村地区酸雨发生频率高于城市地区，酸雨pH值小于5.6及以下。至于公共卫生和安全，在酸雨事件期间，所有雨水样本均超过了国家水质标准（NWQS）和世界卫生组织（WHO）标准的允许限值，表明不适合皮肤接触、娱乐用途甚至饮用。
