Arsenic speciation of geothermal waters in New Zealand

Abstract

Total arsenic and four arsenic species; arsenite (iAs(III)), arsenate (iAs(V)), dimethylarsinic acid (DMA(V)) and monomethylarsonic acid (MA(V)), are reported in 28 geothermal features from the Taupo Volcanic Zone (TVZ) and Waikato region of New Zealand. Samples were collected for arsenic speciation analysis via a solid phase extraction (SPE) kit allowing the separation, stabilisation and pre-concentration of the species at the time of sample collection in the field. This is the first research to present data for arsenic species collected by this technique in geothermal waters from New Zealand. Total arsenic concentrations, determined by inductively coupled plasma mass spectrometry (ICP-MS), ranged from 0.008 to 9.08 mg l⁻¹ As. The highest levels were discovered in three features in Tokaanu (Taumatapuhipuhi, Takarea #5 and #6), with arsenic concentrations of 8.59, 8.70 and 9.08 mg l⁻¹ As, respectively. Inorganic arsenic species were predominant in the geothermal waters, with arsenite contributing to more than 70% of the total arsenic in the majority of samples. Organic species were also determined in all samples, indicating the presence of microbial activity. A potential risk to human health was highlighted due to the high levels of arsenic, mainly as arsenite, in geothermal features linked to bathing pools. Further research is needed into dermal absorption as a potential route of arsenic exposure whilst bathing in these hot pools, as it may contribute to an occurrence of acute arsenic-related health problems.

Phosphorus and arsenic distributions in a seasonally stratified, iron- and manganese-rich lake: microbiological and geochemical controls

“…Phosphorus is an essential, often limiting, nutrient and has a strong effect on the trophic status of water bodies where it can trigger eutrophication where present in excess [3,4] . Arsenic is a biotoxic element which typically accumulates in iron-rich sedimentary aquifer systems [5,6] , but which is commonly present at elevated concentrations in surface waters receiving geothermal discharges [7,8] . Despite the quite different environmental concerns regarding P and As, their environmental fate and behaviour are often controlled by common mechanisms due to the very similar chemical structure and reactivity of their inorganic anions [9] .…”

Atomic spectrometry updates. Review of advances in elemental speciation

“…In New Zealand, a study of geothermal water from 28 geothermal features has been conducted to determine the levels of As III , As V , MMA and DMA. 104 Samples were collected for speciation analysis using SPE to facilitate separation, stabilisation and pre-concentration of the species at the time of sample collection in the eld prior to later analysis by ICP-MS. Total As concentrations ranged from 0.008 to 9.08 mg L À1 As. Inorganic As species were predominant in the geothermal waters, with As III contributing to more than 70% of the total As in the majority of samples.…”

Heavy Metals Analysis in Human Body (Toenail, Fingernail and Hair Samples) and Drinking Waters of Santa Fe Region, Argentina

“…In Tokaanu, three features were identified to contain the highest levels of arsenic concentrations (8.59, 8.70 and 9.08 mg/L As). Geothermal waters were predominantly the source of inorganic arsenic species, with more than 70% arsenite of total arsenic in most of the samples [13]. The study highlighted a serious risk to human health due to the high levels of arsenite as it was linked to bathing pools [13].…”

“…The study highlighted the higher concentrations of heavy metals in tap water when compared to bottled water and how those heavy metals contaminants in both the two sources can adversely affect the functions of haemoglobin and kidney of consumers. About 28 different geothermal features from the Waikato region and Taupo volcanic zone (TVZ) New Zealand, were reported to contain significant concentrations of total arsenic and four of its species; monomethyl arsonic acid, arsenate, arsenite and dimethyl arsonic acid [13]. In Tokaanu, three features were identified to contain the highest levels of arsenic concentrations (8.59, 8.70 and 9.08 mg/L As).…”

“…Geothermal waters were predominantly the source of inorganic arsenic species, with more than 70% arsenite of total arsenic in most of the samples [13]. The study highlighted a serious risk to human health due to the high levels of arsenite as it was linked to bathing pools [13]. Biomarkers that are often used to evaluate environmental exposure to arsenic and selenium (and other trace elements) about human health and diseases are hair and nails [14,15,16].…”