Delineation of Groundwater Salinity Zones in Shefa and Malampa Provinces, Vanuatu

A preliminary assessment was carried out in identifying the salinity zones due to considerable concern over salty groundwater resources in Vanuatu’s Shefa and Malampa regions. Electrical conductivity (EC) and pH were measured on the islands of Efate, Lamen, and Nguna in Shefa province, as well as the islands of Ambrym and Paama in Malampa province. Thirty-four percent of the samples exceeded Vanuatu’s National Drinking Water Standards with an average of 3123 μS/Cm indicating possible salinity zones. Whereas the average pH of 7.21 was in the range of acceptable levels. EC values as high as 18,520 μS/cm indicate groundwater in some locations are unfit for drinking. The average Total Dissolved Solids (TDS) of 1717 mg.L-1 is also indicating non-compliance with standards. Salinity zone maps were developed based on the observations. Further detailed studies need to be conducted to ascertain the factors that influence groundwater salinity, such as geology, island type, and seasonality.

Aquatic contaminants in Solomon Islands and Vanuatu: Evidence from passive samplers and Microtox toxicity assessment

Water Quality issues in many Pacific countries are rising, with the increase in coastal populations and associated urban runoff but management requires contamination issues in the aquatic environment to be identified and prioritised. In Vanuatu and Solomon Islands there are few laboratories and resources to assess for the presence or impact of complex chemical contaminants. The extent and impact of chemical contamination of the marine and coastal environment is poorly described. Passive chemical samplers were used to measure a range of aquatic pollutants around the capital cities, Honiara (Solomon Islands) and Port Vila (Vanuatu). We detected a range of chemicals indicative of agricultural and industrial contamination and a few sites had concerning concentrations of specific hydrocarbons and pesticides. The rapid ecotoxicology test, Microtox, indicated toxic impacts in rivers, coastal sites and urban drains This work provides new data on chemical contamination and possible impacts of that contamination for both countries. The techniques could be applied widely across the region to generate critical data for environmental management, guide monitoring efforts and measure the impact of policy or land-use changes.