Arsenic in Groundwater Sources from Selected Communities Surrounding Taal Volcano, Philippines: An Exploratory Study

Abstract

Arsenic (As) is a highly toxic, carcinogenic trace metal that can potentially contaminate groundwater sources in volcanic regions. This study provides the first comparative documentation of As concentrations in groundwater in a volcano-sedimentary region in the Philippines. Matched, repeated As measurements and physico-chemical analyses were performed in 26 individual wells from 11 municipalities and city in Batangas province from July 2020 to November 2021. Using the electrothermal atomic absorption spectrometric method, analysis of the wells revealed that in 2020, 23 out of 26 (88.46%) had As levels above the WHO limit of >10 ppb while 20 out of 26 wells (76.92%) had persistently high As levels a year later. Using a Wilcoxon signed-rank test, levels of As were found to be statistically elevated compared to the national safe limit of 10 pbb in the 26 matched sampling sites in both 2020 (p-value < 0.001) and 2021 (p-value = 0.013). Additionally, a two-paired Wilcoxon signed-rank test revealed that As levels were statistically higher in 2020 than in 2021 (p-value = 0.003), suggesting that As levels may be higher in years when there is more volcanic activity; however, this remains to be further elucidated with suitable longitudinal data, as this study is still in its preliminary stages. The data was also analyzed using a bivariable regression, which showed no evidence of a significant relationship between As levels and distance from the danger zone (Taal volcano crater); however, results showed an inverse but statistically insignificant relationship between As levels and elevation. Due to the toxic profile and persistence of As in groundwater in Batangas Province, continuous groundwater As monitoring, timely public health risk communication, and the provision of alternative water sources to affected populations are recommended.

Heavy metal contamination in the soil and Taal Lake Post-Taal Volcano eruption

“…Dangerous arsenic concentration was detected from the wells and other water sources from the surrounding municipalities of Taal volcano. The groundwater is reported to have the volcanic rocks and its contents (Apostol et al, 2022). In relation to this study, Taal Lake has no direct contact to the volcanic materials unlike the groundwater.…”

“…Another factor that may also explain the presence of arsenic in the soil is the ground water contamination. Higher arsenic concentration was detected from the wells and other water sources from the different municipalities surrounding Taal volcano in year 2020 than 2021 (Apostol et al, 2022). Their study explained that the movement of the groundwater had an access to the volcanic contents and also in the soil .…”

Sediment Transport Modeling in the Pasig River, Philippines Post Taal Volcano Eruption

“…Arsenic levels from 26 locations in Batangas near the volcano from 2020 to 2021 were found to be significantly and consistently higher than the World Health Organization (WHO) and Philippine National Standards for Drinking Water (PNSDW) 10 ppb limit. The 2020 levels were comparatively higher than those of 2019, which is believed to be caused by a more active Taal volcano [38]. These findings, in conjunction with various other factors, served as primary motivations for the initiation of the study.…”

Post-Siege Genotoxic Hazards in Lake Lanao, Philippines by Micronucleus Assay

“…A closer look at Table 2 revealed that a higher concentration of Ar, (0.27 mg/L) from snail muscles was detected in site A, which was higher than the national acceptable limit in drinking water set at 0.010 mg/L, although the safe limit for mollusk as food is set at 1mg/kg. Nevertheless, this detection may call for some concerns due to the continued consumption of the snails by the locals because this trace metal, aside from being highly toxic and carcinogenic (Apostol et al 2022), can biomagnify along with other toxic pollutants, that is, to increase in concentration in the living organisms successively at higher levels in the food chain (Hepp 2017).…”