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International audienceIn this study, we report chemical and isotope data for 23 geothermal water samples collected in New Zealand within the Taupo Volcanic Zone (TVZ). We analyzed major and trace elements including Li, B and Sr and their isotopic compositions (delta7Li, delta11B, 87Sr/86Sr) in high temperature geothermal waters collected from deep boreholes in different geothermal fields (Ohaaki, Wairakei, Mokai, Kawerau and Rotokawa geothermal systems). Lithium concentrations are high (from 4.5 to 19.9 mg/L) and lithium isotopic compositions (delta7Li) are very homogeneous, being comprised between -0.5 and +1.4‰. In particular, it is noteworthy that, except the samples from the Kawerau geothermal field having slightly higher delta7Li values (+1.4%), the other geothermal waters have a very constant delta7Li signature around a mean value of 0‰ ± 0.6 (2s, n=21). Boron concentrations are also high and relatively homogeneous for the geothermal samples, falling between 17.5 and 82.1 mg/L. Boron isotopic compositions (delta11B) are all negative, and display a range between -6.7 and -1.9‰. These B isotope compositions are in agreement with those of the Ngawha geothermal field in New Zealand. Li and B isotope signatures are in a good agreement with a fluid signature mainly derived from water/rock interactions involving magmatic rocks with no evidence of seawater input. On the other hand, strontium concentrations are lower and more heterogeneous and fall between 2 and 165 µg/L. 87Sr/86Sr ratios range from 0.70549 to 0.70961. These Sr isotope compositions overlap those of the Rotorua geothermal field in New Zealand, also confirming that some geothermal waters (with more radiogenic strontium) have interacted with bedrocks from the metasedimentary basement. Each of these isotope systems on their own reveals important information about particular aspects of either water source or water/rock interaction processes, but, considered together, provide a more integrated understanding of the geothermal systems from the TVZ in New Zealand

Soluble inorganic As is toxic with both cancer and non-cancer endpoints. Of the 80 million people in West Bengal, 50 million are living in the nine As-affected districts with millions at risk from using water for drinking, cooking or irrigation (Chakrabortiet al., 2004). An environmental tragedy is developing in West Bengal with an alarming number of cases of skin lesions (Guha Mazumderet al., 1998; Mukherjeeet al., 2005), respiratory symptoms (von Ehrensteinet al., 2005), adverse pregnancy outcomes and infant mortality (von Ehrensteinet al., 2006) and neurological complications (Mukherjeeet al., 2005) associated with ingestion of As-contaminated water.

We combined statistical analyses and GIS capabilities within the statistical environment R to create a semi-automated method for the assessment of As hazard risk in shallow groundwater in Cambodia. Arsenic concentration data for groundwaters of between 16 and 100 m depth were obtained from 1437 geo-referenced wells. We created a binary logistic regression model with these As measurements as the dependent variable and a number of raster maps (DEM-parameters, remote sensing images and geomorphology) as explanatory variables, and considering an As threshold of 10 ppb. This allowed us to make an As hazard map for groundwaters between 16—100 m depth: this can be used to help to identify populations vulnerable to exposure. The logistic regression analysis indicates a good correlation between topographic and geomorphologic environmental variables and the As hazard risk in groundwater. Ease of implementation, and the ability to update, along with objectivity and reproducibility are the main advantages related to this method of analysis.