water Article Spatiotemporal Variation of Groundwater Arsenic in Pampanga, Philippines Kurt Louis B. Solis 1, Reygie Q. Macasieb 1, Roel C. Parangat Jr. 1, Augustus C. Resurreccion 1,* and Joey D. Ocon 2,* 1 Institute of Civil Engineering, College of Engineering, University of the Philippines Diliman, Quezon City 1101, Philippines;
[email protected] (K.L.B.S.);
[email protected] (R.Q.M.);
[email protected] (R.C.P.J.) 2 Laboratory of Electrochemical Engineering (LEE), Department of Chemical Engineering, College of Engineering, University of the Philippines Diliman, Quezon City 1101, Philippines * Correspondence:
[email protected] (A.C.R.);
[email protected] (J.D.O.); Tel.: +63-(02)-3434-3635 (J.D.O.) Received: 15 July 2020; Accepted: 13 August 2020; Published: 24 August 2020 Abstract: Several confirmed cases of arsenic (As) poisoning have been reported in Central Luzon, the Philippines, in recent years. There is a growing interest in As research in the Philippines due to the reported As poisoning cases. However, an extensive spatiotemporal As study has not been conducted. In this work, As concentration measurements were conducted in 101 wells in Guagua, Pampanga, in Central Luzon, the Philippines, from November 2018 to November 2019. The wells included 86 public hand pumps, 10 pumping stations, and 5 private, jet-powered pumps. Using hydride generation—inductively coupled plasma—optical emission spectroscopy (HG-ICP-OES), analysis of the wells in 12 barangays in Guagua revealed that 38.7% had average As concentrations beyond the 10 ppb limit with some wells having high Mn (4.0 ppm) and Fe (2.0 ppm) content as well.